CA2142643A1 - Snowmobile floatation system - Google Patents
Snowmobile floatation systemInfo
- Publication number
- CA2142643A1 CA2142643A1 CA 2142643 CA2142643A CA2142643A1 CA 2142643 A1 CA2142643 A1 CA 2142643A1 CA 2142643 CA2142643 CA 2142643 CA 2142643 A CA2142643 A CA 2142643A CA 2142643 A1 CA2142643 A1 CA 2142643A1
- Authority
- CA
- Canada
- Prior art keywords
- snowmobile
- flotation
- inflatable
- water
- ice
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60F—VEHICLES FOR USE BOTH ON RAIL AND ON ROAD; AMPHIBIOUS OR LIKE VEHICLES; CONVERTIBLE VEHICLES
- B60F3/00—Amphibious vehicles, i.e. vehicles capable of travelling both on land and on water; Land vehicles capable of travelling under water
- B60F3/003—Parts or details of the vehicle structure; vehicle arrangements not otherwise provided for
- B60F3/0038—Flotation, updrift or stability devices
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60F—VEHICLES FOR USE BOTH ON RAIL AND ON ROAD; AMPHIBIOUS OR LIKE VEHICLES; CONVERTIBLE VEHICLES
- B60F3/00—Amphibious vehicles, i.e. vehicles capable of travelling both on land and on water; Land vehicles capable of travelling under water
- B60F3/0061—Amphibious vehicles specially adapted for particular purposes or of a particular type
- B60F3/0076—Amphibious snowmobiles
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60R—VEHICLES, VEHICLE FITTINGS, OR VEHICLE PARTS, NOT OTHERWISE PROVIDED FOR
- B60R21/00—Arrangements or fittings on vehicles for protecting or preventing injuries to occupants or pedestrians in case of accidents or other traffic risks
- B60R2021/0002—Type of accident
- B60R2021/0016—Fall in water
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60R—VEHICLES, VEHICLE FITTINGS, OR VEHICLE PARTS, NOT OTHERWISE PROVIDED FOR
- B60R21/00—Arrangements or fittings on vehicles for protecting or preventing injuries to occupants or pedestrians in case of accidents or other traffic risks
- B60R2021/0065—Type of vehicles
- B60R2021/0074—Utility vehicles
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
- B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING
- B63B43/00—Improving safety of vessels, e.g. damage control, not otherwise provided for
- B63B43/02—Improving safety of vessels, e.g. damage control, not otherwise provided for reducing risk of capsizing or sinking
- B63B43/10—Improving safety of vessels, e.g. damage control, not otherwise provided for reducing risk of capsizing or sinking by improving buoyancy
- B63B43/14—Improving safety of vessels, e.g. damage control, not otherwise provided for reducing risk of capsizing or sinking by improving buoyancy using outboard floating members
- B63B2043/145—Improving safety of vessels, e.g. damage control, not otherwise provided for reducing risk of capsizing or sinking by improving buoyancy using outboard floating members pneumatic, e.g. inflatable on demand
Abstract
In a snowmobile having a body with a front end, a middle portion and a back end, top and bottom, and a flotation system integral thereto, said flotation system comprising:
a plurality of inflatable flotation means mounted at spaced locations on said snowmobile including two inflatable flotation means on opposed sides interior and underneath of said middle portion and one inflatable flotation means located interior and underneath of said front end; a compressed gas source; conduit means connecting said gas source with each of said inflatable flotation means; actuating means for releasing said compressed gas from said source to inflate said inflatable flotation means, said actuating means being integral with said source; each of said flotation means further comprising an inflatable envelope fluidly connected to said fluid passageway means, said envelope being collapsed prior to inflation, interiorly, underneath and within said body of said snowmobile enclosed by a sealed waterproof cover, continuous in nature.
a plurality of inflatable flotation means mounted at spaced locations on said snowmobile including two inflatable flotation means on opposed sides interior and underneath of said middle portion and one inflatable flotation means located interior and underneath of said front end; a compressed gas source; conduit means connecting said gas source with each of said inflatable flotation means; actuating means for releasing said compressed gas from said source to inflate said inflatable flotation means, said actuating means being integral with said source; each of said flotation means further comprising an inflatable envelope fluidly connected to said fluid passageway means, said envelope being collapsed prior to inflation, interiorly, underneath and within said body of said snowmobile enclosed by a sealed waterproof cover, continuous in nature.
Description
2~ 4~64~
SUMMARY OF THE INVENTION
In one embodiment there is provided a snowmobile having a body with a front end, a middle portion and a back end, top and bottom, and a flotation system integral thereto, said flotation system comprlsing:
a plurality of inflatable flotation means mounted at spaced locations on said snowmobile including two inflatable flotation means on opposed sides interior and underneath of said middle portion and one inflatable flotation means located interior and underneath of said front end; a compressed gas source; conduit means connecting said gas source with each of said inflatable flotation means; actuating means for releasing said compressed gas from said source to inflate said inflatable flotation means, said actuating means being integral with said source; each of said flotation means further comprising an inflatable envelope fluidly connected to said fluid passageway means; said envelope being collapsed prior to inflation, interiorly, underneath and within said body of said snowmobile enclosed by a sealed waterproof cover, continuous in nature.
In another embodiment the flotation system described herein further comprising an integral puncture actuator and cannister system with conduit means connected to said cannister..
In yet another embodiment the flotation system described herein further comprises said actuator including a manually actuable handle fluidly connected to a puncturing means.
X~ `t_ I ~f SPECIFICATION
1.0 Introduction Snowmobiling is a popular winter sport in Ontario. Unfortunately, there a numberof snowmobiling accidents that occur each year. A significant proportion of these accidents are water-related, and arise from snowmobiles breaking through thin ice, or encountering open water conditions while travelling on lakes and rivers.
A Snowmobile Floatation System has been proposed to permit the snowmobile and riders to stay afloat on the surface of the water after an accident has occured.
This report examines the accident problem in Ontario, and presents a possible design solution for such a floatation system.
2~ ~26~3 2.0 Water-Related Snowmobile Accidents in Ontario 2.1 Snowmobiling as a Re~reational Sport in Ontario Snowmobiling continues to be a popular winter recreational sport for people in Ontario. Statistics from the Ontario Ministry of Transportation [1] indicate that, for the years 1986 to 1992, an average of about 21,500 new snowmobiles per year wereregistered in the province. To service this growth, Ontario boasts one of the most extensive and well organized snowmobile club and trail systems in the world. Apart from being an enjoyable winter pastime for Ontarians, the sport of snowmobiling has proven to provide a significant economic base to the central and northem regions of the province. To further stimulate growth in the snowmobiling tourism industry, the Ontario Goverrlment has recently provided approximately 14 rnillion dollars in funding to expand and upgrade the existing Irail network.
Due to the abundance of lakes and rivers in Ontario, much snowmobiling is done on or near ice. Under proper conditions, ice travel by snowmobile provides a means to enjoy and explore parts of the province that are otherwise difficult to reach during winter. However, a serious problem results when snowmobilers attempt to travel on ice that is thin or of poor quality. Each winter in Ontario, there are a number of snowmobile accidents that invlove breaking through thin ice. The typical result of these accidents is death due to drowning, exposure, or catastrophic injury.
2.2 Accident Statistics Limited statistics on water-related snowmobile accidcnts are available for two main groups: fatalities and catastrophic injuries. Ice breakthroughs that do not result in one of these effects generally go unreported and are therfore very difficult to quantify. The following data has been compiled from several different sources The most recent data available is for the snowmobiling seasons of 1992/93 and 1993 /94. The information was provided by the Ontario Provincial Police, Traffic and Marine Branch, Orillia, Ontario.
In the season of 1992/93, there were 30 reported snowmobile accidents, of which. 17 were alcohol-related and 7 were water-related. I n~l~ ...,re 35 people were killed in 2 ~ ~2 ~
thesc accidents. In the season of 1993/94, thcrc werc 23 reported accidcnts, of which I l were alcohol-related and S were water-related These accidcnts resulted in 23fatalitics. . The dates, locations and circu.,~l~nccs of the water-relatcd fatalities are summarized in Tables 2.1 and 2.2. The numbcr of fatalities involved in each incident was unavailable.
Invecti~atin~ Police Accident Date Accident Circumstances N.E. Patrol, South 18 Dec. 1992 - thin ice, drowned Porcupine OPP~ Espanola Detachment 23 Dec. 1992 - broke thru thin ice, drowned OPP~ Haileybury Detach. 24 Dec. 1992 - broke thru thin ice, drowned OPP~ Brockville Detachment 18 Jan. 1993 - throu~h ice, drowned OPP~ Huntsville Detachment 23 Jan. 1993 - hit open water, downed OPP. Midland Detachment 24 Jan. 1993 - drove on opcn water, drowned OPP. PalTy Sound Detach. 29 Jan. 1993 - broke thru thin ice, drowned Table 2.1: 1992/93 Reported Water-Related Accidentc Invecti~atin~ Police Accident Date Accident Circvmct~-lces N.W. Patrol. Souix Lookout 12 Nov. 1993 - open water, drowned OPP. Kenora Detachment 20 Nov. 1993 - unsafe ice, drowned OPP. Orillia Detachment 26 Dcc. 1993 - travclling on thin ice, drowned N.W. Patrol 30 Dcc. 1993 - thin ice, drowned OPP, Shubaque Detachment 23 April 1994 - hit open water, drowned Table 2.2: 1993/94 Reported Water-Related Accidents The Royal Lifc Saving Society Canada, Ontario Branch, has compiled data from theChicf Coroncr's Office, of the number of water-related accidental deaths per year for various rccreational activities in Ontario. Figure 2.3 [2] shows that, for the years 1987-1992, thcre was an average of 14 water-related deaths per year due to snowmobiling. This puts snowmobiling in the top 7 recreational activities for Ontario waur-related accidental deaths. On a national level, there was an average of 27 accidental water-related fatalities per year in Canada from 1990-92 due to snowmobiling on thin ice [3].
2~ ~2~
Top 7 Recrcational Ach~itus in Ontario Watcr-Rclatet Acc dental Deaths - Six Year Ar~eragcs for 1987 - 1992: ~ of deaths per year (Combined Primary and Secondary Act~i~ies~
so . ..
~s! ~
1. 111 Po , F_~ ~ ~o ~U W~ ~u ~ n,, C~
Figure 23: Avg # of Water Related Snowmobiling Deaths Per Year 1987 92 Aside from deaths, many non-fatal catastrophic water-related injuries occur each year due to snowmobiling ice breakthroughs. The Think First Foundation of Canada. in their "Ontario Sports Recreational Injuries Survey 1992", reports that there were 10 water-related injuries due to snowmobiling in 1989. and S in 1992. Figure 2.4 [2]
shows that water-related injuries arising from snowmobiling accidents are co~ ~dble in number to those of boating. for the years examined. Most of the snowmobiling injuries are a result of hypothermia induced from being exposed to very low ~,..~,ature waters.
~4~
Ontano Non-Fatal Catastrophic Water-Related Injuries - By Recreational Ach~ity and Total: 1989 and 1992 - # of injunes .._ ~
_ ~ Ir_ ~
2 ~ 2 ~ --2 ~ 2 ~ 2 D~rno m~o w~ o~n~ ~r~_m~ Orn~r Tou~
Source: Ontario Sports Reeational ~ siff Survey 1992", SportSmart Canada, Mat~ 1993 Figure 2.4: Non-Fatal Catastrophic Water Related Injuries From Snovvmobiling 2 3 T~TPjCal Acciden~ Conditions and Occurances Snowmobilc icc brcakthroughs occur all throughout thc winter months, but most sccm to occur carly in thc season. This can be partly attTibuted to thc rclativcly non-uniforrn and unpredictablc icc conditions associated with thc freezing of lakcs and rivcrs at the start of thc season. Often a body of watcr will dcvclop a thin laycr of ice, and then rcccivc a significant layer of snow on top. This acts as an insul~tor which impedes furthcr thickening of thc icc, evcn though ambicnt t~.llpC.dCS may be below thefreezing point. Anothcr reason for thc high incidence of accidents early in the season.
is the fact that many snowmobilers are so eager to get their first ride of the scason, that thcy fail to rccognize thc possibility of dangcrous ice conditions.
The ~ypical areas for thin ice snowmobile accidents to occur, are areas of currcnts, or otherwise non-stationary watcrs. It is thesc areas where ice may not form at all, or may form to depth that is insufficient in strength to support the weight of a snowmobile. Rivers are the most dangerous to travel on. The water is usually always moving undc,llcalh and shif~ng cull~r.b can make for rapid fluctuations in ice conditions. The arcas of lakes that are most dangerous are narrows, such as entrances 2~2643 to bays or underneath bridges, shoals, or locations where rivers empty into or flow out of lakes.
Most ice accidents occur at night .. hcA tqe when the visibility distance is limited to that of the snowmobile's headlight. With thc rclativcly high cruising speeds afforded by modern snowmobiles, there is usually not cnough timc to rcact to avoid dangeroncc dctccted. Travelling at night also can Icad operators into unfamiliar territory due to the difficulty in distunguishing landmarks.
According to the Ontario Provincial Police and the Royal Life Saving Society of Canada [3], alcohol is involved in approximately 40 -50% of all investigated snowmobile accidents. The effect of impairment on the judgement and reaction time of an operator significantly reduces his/her ability to avoid dangerous ice conditions.
When snowmobiles break through thin ice, they usually do so at relatively slow speeds. Travelling at very high speeds can actually allow a snowmobile to continue indefinitely, even on very thin ice. However, many regions of thin ice or open water are surrounded by thick, heavy snow or slush. This has the effect of slowing thesnowmobile down signi~lcantly due to the tremendous drag forccs imposed by this type of surface condition. Upon breaking through, the snowmobile is usually sinks straight down, with a relatively flat ~ Udc. and is complctely subl-~,gcd in about 2-3 seconds.
When a snowmobile operator or passengcr of a sirlking snowmobile contacts the freczing watcr, thcy typically havc betwecn 5 and 10 seconds to gct out before being overcome by thc paralyzing cffcct of thc trcmendous body hcat loss. Aftcr this point~
it is virtually impossible for the person be able to stay afloat to prevent from drowning.
The amount of watcr that can be absorbed by a typical snowmobilc suit and set ofboots is cnough to increasc the ridcr's cffcctivc wcight to the point whcrc it is very difficult to pull himself/herself up from thc water onto the icc surfacc withoutassistancc. Evcn if the person does managc to gct out of the water, hc/she has very little timc to obtain warm~h before succumbing to cxposure.
21426~3 2.4 Prevention of Water-Related Snowmobile Accidents Water-related snowmobile accidents happen frequently enough that they are regarded as a very real and significant hazard in the sport. The Ontario Federation of Snowmobile Clubs (O.F.S.C) recognizes their significance and is currently taking steps to fully assess the magnitude and effect of the problem. The O.F.S.C has recently commissioned Tandem Intemational Inc. management consultants, to perfomm a detailed, 5-year analysis of fatalities resulting from water-related snowmobile accidents in the province. The report is scheduled to be completed by mid February, 1995.
Snowmobile accidents of all types only serve to detract from the sport, hence, it is of the Federation's best interest to understand the problems, so that it may educate snowmobilers on how to avoid incidents and make the sport safer.
Other agencies are also interested in preventing water-related snowmobile accidents.
The Royal Life Saving Society Canada (RLSSC), compiles accident statistics yearly in the fomm of provincial and national reports to help educate society abou~ drownings and water-related accidents. It is the C~n~ n authority in water survival education and life guarding.
The Think First Foundation of Canada (Formerly SponSmart Canada) of the Toronto Hospital, Western Division, compiles data on catastrophic and trauma injuries as a result of water-related snowmobile accidents. The organi~tion publishes a reportevery three years sumrnarizing injuries called the "Ontario Sports Recreational Injuries Survey". Another agency, the Safety Resource Centre, Toronto, serves as an inforrnation source for the public on safety _nd accident prevention. The Centre offers literature and video information on snowmobile safety. The Ontario Provincial Police have special units such as the Tr_ffic and Marine Branch based in Orillia, Ontario, that serve to monitor accidents in the province, as well as offering certain courses on safe snowmobile operation. The OPP also pclfol~ll snowmobile patrolled RIDE prograrnsin parts of the trail networks, in an attempt to reduce the number of impaired snowmobiliers.
A committee has been formed in province called the Ontario Snowmobile Safety Committee, which has as its mandate the advancement of the sport's safety level. The co.lu..,l~c consists primarily of representatives from the aforementioned agencies.
The committee meets monthly to discuss means of accident prevention.
6~
Aside from the current efforts being undertaken by the various organizationS in Ontario to help prevent snowmobile accidents, Iegislation by the provincial govemment may also help reduce the casualties each year. Presently in Ontario, there is no requirement of an operator of a snowmobile to have a license. The snowmobile itself must be licensed, but there is no fommal way of ~ccessing the co..-~unce of a snowmobiler in the safe operation of his or her m~chine. Imposing a license of this sort may serve to more fully educate and train ope~ators on how to assess and/or avoid dangerous ice conditions, and what to do in order to increase the chances of survival in the event of an accident. Other legislation possibilities include: providing regulations for mandatory safety equipment such as buoyant snowmobile sui~s, lifejackets, etc.. Iake travel safety regulations, and the provision of more police instituted RIDE programs, to reduce alcohol consumption on the trails.
In yet another embodiment of the flotation system said actuator further comprises an electrically operated explosive charge for automatic operation of said puncturing means.
In yet another embodiment of the flotation system further comprising a flotation responsive switch mounted in a strategic location proximate the bottom immediately adjacent the exhaust pipe exit.
In yet another embodiment of the flotation system said inflatable envelope further comprises material substantially resistant to ice puncture and the like.
In yet another embodiment of the flotation system said system is used for saving lives in the event of said snowmobile falling through ice.
Further and other objects of the invention will become apparent to those skilled in the art when considering the specification.
As many changes can be made to the preferred embodiments of the invention without departing from the scope of the invention, it is intended that all material contained herein be interpreted as illustrative of the invention and not in a limiting sense.
SUMMARY OF THE INVENTION
In one embodiment there is provided a snowmobile having a body with a front end, a middle portion and a back end, top and bottom, and a flotation system integral thereto, said flotation system comprlsing:
a plurality of inflatable flotation means mounted at spaced locations on said snowmobile including two inflatable flotation means on opposed sides interior and underneath of said middle portion and one inflatable flotation means located interior and underneath of said front end; a compressed gas source; conduit means connecting said gas source with each of said inflatable flotation means; actuating means for releasing said compressed gas from said source to inflate said inflatable flotation means, said actuating means being integral with said source; each of said flotation means further comprising an inflatable envelope fluidly connected to said fluid passageway means; said envelope being collapsed prior to inflation, interiorly, underneath and within said body of said snowmobile enclosed by a sealed waterproof cover, continuous in nature.
In another embodiment the flotation system described herein further comprising an integral puncture actuator and cannister system with conduit means connected to said cannister..
In yet another embodiment the flotation system described herein further comprises said actuator including a manually actuable handle fluidly connected to a puncturing means.
X~ `t_ I ~f SPECIFICATION
1.0 Introduction Snowmobiling is a popular winter sport in Ontario. Unfortunately, there a numberof snowmobiling accidents that occur each year. A significant proportion of these accidents are water-related, and arise from snowmobiles breaking through thin ice, or encountering open water conditions while travelling on lakes and rivers.
A Snowmobile Floatation System has been proposed to permit the snowmobile and riders to stay afloat on the surface of the water after an accident has occured.
This report examines the accident problem in Ontario, and presents a possible design solution for such a floatation system.
2~ ~26~3 2.0 Water-Related Snowmobile Accidents in Ontario 2.1 Snowmobiling as a Re~reational Sport in Ontario Snowmobiling continues to be a popular winter recreational sport for people in Ontario. Statistics from the Ontario Ministry of Transportation [1] indicate that, for the years 1986 to 1992, an average of about 21,500 new snowmobiles per year wereregistered in the province. To service this growth, Ontario boasts one of the most extensive and well organized snowmobile club and trail systems in the world. Apart from being an enjoyable winter pastime for Ontarians, the sport of snowmobiling has proven to provide a significant economic base to the central and northem regions of the province. To further stimulate growth in the snowmobiling tourism industry, the Ontario Goverrlment has recently provided approximately 14 rnillion dollars in funding to expand and upgrade the existing Irail network.
Due to the abundance of lakes and rivers in Ontario, much snowmobiling is done on or near ice. Under proper conditions, ice travel by snowmobile provides a means to enjoy and explore parts of the province that are otherwise difficult to reach during winter. However, a serious problem results when snowmobilers attempt to travel on ice that is thin or of poor quality. Each winter in Ontario, there are a number of snowmobile accidents that invlove breaking through thin ice. The typical result of these accidents is death due to drowning, exposure, or catastrophic injury.
2.2 Accident Statistics Limited statistics on water-related snowmobile accidcnts are available for two main groups: fatalities and catastrophic injuries. Ice breakthroughs that do not result in one of these effects generally go unreported and are therfore very difficult to quantify. The following data has been compiled from several different sources The most recent data available is for the snowmobiling seasons of 1992/93 and 1993 /94. The information was provided by the Ontario Provincial Police, Traffic and Marine Branch, Orillia, Ontario.
In the season of 1992/93, there were 30 reported snowmobile accidents, of which. 17 were alcohol-related and 7 were water-related. I n~l~ ...,re 35 people were killed in 2 ~ ~2 ~
thesc accidents. In the season of 1993/94, thcrc werc 23 reported accidcnts, of which I l were alcohol-related and S were water-related These accidcnts resulted in 23fatalitics. . The dates, locations and circu.,~l~nccs of the water-relatcd fatalities are summarized in Tables 2.1 and 2.2. The numbcr of fatalities involved in each incident was unavailable.
Invecti~atin~ Police Accident Date Accident Circumstances N.E. Patrol, South 18 Dec. 1992 - thin ice, drowned Porcupine OPP~ Espanola Detachment 23 Dec. 1992 - broke thru thin ice, drowned OPP~ Haileybury Detach. 24 Dec. 1992 - broke thru thin ice, drowned OPP~ Brockville Detachment 18 Jan. 1993 - throu~h ice, drowned OPP~ Huntsville Detachment 23 Jan. 1993 - hit open water, downed OPP. Midland Detachment 24 Jan. 1993 - drove on opcn water, drowned OPP. PalTy Sound Detach. 29 Jan. 1993 - broke thru thin ice, drowned Table 2.1: 1992/93 Reported Water-Related Accidentc Invecti~atin~ Police Accident Date Accident Circvmct~-lces N.W. Patrol. Souix Lookout 12 Nov. 1993 - open water, drowned OPP. Kenora Detachment 20 Nov. 1993 - unsafe ice, drowned OPP. Orillia Detachment 26 Dcc. 1993 - travclling on thin ice, drowned N.W. Patrol 30 Dcc. 1993 - thin ice, drowned OPP, Shubaque Detachment 23 April 1994 - hit open water, drowned Table 2.2: 1993/94 Reported Water-Related Accidents The Royal Lifc Saving Society Canada, Ontario Branch, has compiled data from theChicf Coroncr's Office, of the number of water-related accidental deaths per year for various rccreational activities in Ontario. Figure 2.3 [2] shows that, for the years 1987-1992, thcre was an average of 14 water-related deaths per year due to snowmobiling. This puts snowmobiling in the top 7 recreational activities for Ontario waur-related accidental deaths. On a national level, there was an average of 27 accidental water-related fatalities per year in Canada from 1990-92 due to snowmobiling on thin ice [3].
2~ ~2~
Top 7 Recrcational Ach~itus in Ontario Watcr-Rclatet Acc dental Deaths - Six Year Ar~eragcs for 1987 - 1992: ~ of deaths per year (Combined Primary and Secondary Act~i~ies~
so . ..
~s! ~
1. 111 Po , F_~ ~ ~o ~U W~ ~u ~ n,, C~
Figure 23: Avg # of Water Related Snowmobiling Deaths Per Year 1987 92 Aside from deaths, many non-fatal catastrophic water-related injuries occur each year due to snowmobiling ice breakthroughs. The Think First Foundation of Canada. in their "Ontario Sports Recreational Injuries Survey 1992", reports that there were 10 water-related injuries due to snowmobiling in 1989. and S in 1992. Figure 2.4 [2]
shows that water-related injuries arising from snowmobiling accidents are co~ ~dble in number to those of boating. for the years examined. Most of the snowmobiling injuries are a result of hypothermia induced from being exposed to very low ~,..~,ature waters.
~4~
Ontano Non-Fatal Catastrophic Water-Related Injuries - By Recreational Ach~ity and Total: 1989 and 1992 - # of injunes .._ ~
_ ~ Ir_ ~
2 ~ 2 ~ --2 ~ 2 ~ 2 D~rno m~o w~ o~n~ ~r~_m~ Orn~r Tou~
Source: Ontario Sports Reeational ~ siff Survey 1992", SportSmart Canada, Mat~ 1993 Figure 2.4: Non-Fatal Catastrophic Water Related Injuries From Snovvmobiling 2 3 T~TPjCal Acciden~ Conditions and Occurances Snowmobilc icc brcakthroughs occur all throughout thc winter months, but most sccm to occur carly in thc season. This can be partly attTibuted to thc rclativcly non-uniforrn and unpredictablc icc conditions associated with thc freezing of lakcs and rivcrs at the start of thc season. Often a body of watcr will dcvclop a thin laycr of ice, and then rcccivc a significant layer of snow on top. This acts as an insul~tor which impedes furthcr thickening of thc icc, evcn though ambicnt t~.llpC.dCS may be below thefreezing point. Anothcr reason for thc high incidence of accidents early in the season.
is the fact that many snowmobilers are so eager to get their first ride of the scason, that thcy fail to rccognize thc possibility of dangcrous ice conditions.
The ~ypical areas for thin ice snowmobile accidents to occur, are areas of currcnts, or otherwise non-stationary watcrs. It is thesc areas where ice may not form at all, or may form to depth that is insufficient in strength to support the weight of a snowmobile. Rivers are the most dangerous to travel on. The water is usually always moving undc,llcalh and shif~ng cull~r.b can make for rapid fluctuations in ice conditions. The arcas of lakes that are most dangerous are narrows, such as entrances 2~2643 to bays or underneath bridges, shoals, or locations where rivers empty into or flow out of lakes.
Most ice accidents occur at night .. hcA tqe when the visibility distance is limited to that of the snowmobile's headlight. With thc rclativcly high cruising speeds afforded by modern snowmobiles, there is usually not cnough timc to rcact to avoid dangeroncc dctccted. Travelling at night also can Icad operators into unfamiliar territory due to the difficulty in distunguishing landmarks.
According to the Ontario Provincial Police and the Royal Life Saving Society of Canada [3], alcohol is involved in approximately 40 -50% of all investigated snowmobile accidents. The effect of impairment on the judgement and reaction time of an operator significantly reduces his/her ability to avoid dangerous ice conditions.
When snowmobiles break through thin ice, they usually do so at relatively slow speeds. Travelling at very high speeds can actually allow a snowmobile to continue indefinitely, even on very thin ice. However, many regions of thin ice or open water are surrounded by thick, heavy snow or slush. This has the effect of slowing thesnowmobile down signi~lcantly due to the tremendous drag forccs imposed by this type of surface condition. Upon breaking through, the snowmobile is usually sinks straight down, with a relatively flat ~ Udc. and is complctely subl-~,gcd in about 2-3 seconds.
When a snowmobile operator or passengcr of a sirlking snowmobile contacts the freczing watcr, thcy typically havc betwecn 5 and 10 seconds to gct out before being overcome by thc paralyzing cffcct of thc trcmendous body hcat loss. Aftcr this point~
it is virtually impossible for the person be able to stay afloat to prevent from drowning.
The amount of watcr that can be absorbed by a typical snowmobilc suit and set ofboots is cnough to increasc the ridcr's cffcctivc wcight to the point whcrc it is very difficult to pull himself/herself up from thc water onto the icc surfacc withoutassistancc. Evcn if the person does managc to gct out of the water, hc/she has very little timc to obtain warm~h before succumbing to cxposure.
21426~3 2.4 Prevention of Water-Related Snowmobile Accidents Water-related snowmobile accidents happen frequently enough that they are regarded as a very real and significant hazard in the sport. The Ontario Federation of Snowmobile Clubs (O.F.S.C) recognizes their significance and is currently taking steps to fully assess the magnitude and effect of the problem. The O.F.S.C has recently commissioned Tandem Intemational Inc. management consultants, to perfomm a detailed, 5-year analysis of fatalities resulting from water-related snowmobile accidents in the province. The report is scheduled to be completed by mid February, 1995.
Snowmobile accidents of all types only serve to detract from the sport, hence, it is of the Federation's best interest to understand the problems, so that it may educate snowmobilers on how to avoid incidents and make the sport safer.
Other agencies are also interested in preventing water-related snowmobile accidents.
The Royal Life Saving Society Canada (RLSSC), compiles accident statistics yearly in the fomm of provincial and national reports to help educate society abou~ drownings and water-related accidents. It is the C~n~ n authority in water survival education and life guarding.
The Think First Foundation of Canada (Formerly SponSmart Canada) of the Toronto Hospital, Western Division, compiles data on catastrophic and trauma injuries as a result of water-related snowmobile accidents. The organi~tion publishes a reportevery three years sumrnarizing injuries called the "Ontario Sports Recreational Injuries Survey". Another agency, the Safety Resource Centre, Toronto, serves as an inforrnation source for the public on safety _nd accident prevention. The Centre offers literature and video information on snowmobile safety. The Ontario Provincial Police have special units such as the Tr_ffic and Marine Branch based in Orillia, Ontario, that serve to monitor accidents in the province, as well as offering certain courses on safe snowmobile operation. The OPP also pclfol~ll snowmobile patrolled RIDE prograrnsin parts of the trail networks, in an attempt to reduce the number of impaired snowmobiliers.
A committee has been formed in province called the Ontario Snowmobile Safety Committee, which has as its mandate the advancement of the sport's safety level. The co.lu..,l~c consists primarily of representatives from the aforementioned agencies.
The committee meets monthly to discuss means of accident prevention.
6~
Aside from the current efforts being undertaken by the various organizationS in Ontario to help prevent snowmobile accidents, Iegislation by the provincial govemment may also help reduce the casualties each year. Presently in Ontario, there is no requirement of an operator of a snowmobile to have a license. The snowmobile itself must be licensed, but there is no fommal way of ~ccessing the co..-~unce of a snowmobiler in the safe operation of his or her m~chine. Imposing a license of this sort may serve to more fully educate and train ope~ators on how to assess and/or avoid dangerous ice conditions, and what to do in order to increase the chances of survival in the event of an accident. Other legislation possibilities include: providing regulations for mandatory safety equipment such as buoyant snowmobile sui~s, lifejackets, etc.. Iake travel safety regulations, and the provision of more police instituted RIDE programs, to reduce alcohol consumption on the trails.
In yet another embodiment of the flotation system said actuator further comprises an electrically operated explosive charge for automatic operation of said puncturing means.
In yet another embodiment of the flotation system further comprising a flotation responsive switch mounted in a strategic location proximate the bottom immediately adjacent the exhaust pipe exit.
In yet another embodiment of the flotation system said inflatable envelope further comprises material substantially resistant to ice puncture and the like.
In yet another embodiment of the flotation system said system is used for saving lives in the event of said snowmobile falling through ice.
Further and other objects of the invention will become apparent to those skilled in the art when considering the specification.
As many changes can be made to the preferred embodiments of the invention without departing from the scope of the invention, it is intended that all material contained herein be interpreted as illustrative of the invention and not in a limiting sense.
3.0 A Snowmobile Flotation System as an Aid During Water~Related Snowmobile Accidents The seriousncss of water-related snowmobile accidents in Ontario has been presented~
along with some of the means that either are, or could be undertaken to reduce the occurrences of the problem. Another proposal, whilc not preventing the accidents from happening, may serve to help save the lives of those who are involved in snowmobile accidents of this panicular type.
The proposal is a Snowmobile Flotation System. The system would provide means for the snowmobile and riders to remain afloat after either breaking through thin ice orencountering open water conditions while traveling on frozen lakes and rivers. The system would prevent the riders from coming in contact with cold waters, thus preventing drowning or exposure, and also would prevent the loss of the snowmobile due to sinking.
The remainder of this report is dedicated to examining possible design solutions and the technical feasibility of such a system.
2I4~643 4.0 De~sign Criteria and Constraints In order for the Snowmobile Flotation System to be an effective aid during water-related snowmobile accidents, it must conform to a set of distinct design criteria and constraints that dictate how the system must perform, and under what limits it must perform.
The Snowmobile Floatation System shall be automatically activated, and must be fully operational within 5 seconds of the commencement of sinking. Provisions must exist for manual activation as a backup for the automatic activation. The system must permit the snowmobile and two riders to remain afloat on the surface of the water for a minimum period of 3 hours after activation The system shall at no time allow the passengers to be exposed to water above the knee level, (as measured in the normal seated operating position)~ or above the snowmobile seat level ,whichever is lower. The Snowmobile Floatation System shall be fully operational under ambient telllpe~atures as low as -40 C.
The Snowmobile Floatation System shall be adaptable to meet the requirements of currently manufactured snowmobiles, and shall not require extensive modifications to the existing vehicle superstructure. All component and pcrforrnancc spa~fic~ions shall be such that they meet a minimum factor of safety of 1.2 above the CAIIClllC anticipated service conditions. The system shall in no way inhibit the safe opcration of thesnowmobile under normal snowmobiling conditions.
along with some of the means that either are, or could be undertaken to reduce the occurrences of the problem. Another proposal, whilc not preventing the accidents from happening, may serve to help save the lives of those who are involved in snowmobile accidents of this panicular type.
The proposal is a Snowmobile Flotation System. The system would provide means for the snowmobile and riders to remain afloat after either breaking through thin ice orencountering open water conditions while traveling on frozen lakes and rivers. The system would prevent the riders from coming in contact with cold waters, thus preventing drowning or exposure, and also would prevent the loss of the snowmobile due to sinking.
The remainder of this report is dedicated to examining possible design solutions and the technical feasibility of such a system.
2I4~643 4.0 De~sign Criteria and Constraints In order for the Snowmobile Flotation System to be an effective aid during water-related snowmobile accidents, it must conform to a set of distinct design criteria and constraints that dictate how the system must perform, and under what limits it must perform.
The Snowmobile Floatation System shall be automatically activated, and must be fully operational within 5 seconds of the commencement of sinking. Provisions must exist for manual activation as a backup for the automatic activation. The system must permit the snowmobile and two riders to remain afloat on the surface of the water for a minimum period of 3 hours after activation The system shall at no time allow the passengers to be exposed to water above the knee level, (as measured in the normal seated operating position)~ or above the snowmobile seat level ,whichever is lower. The Snowmobile Floatation System shall be fully operational under ambient telllpe~atures as low as -40 C.
The Snowmobile Floatation System shall be adaptable to meet the requirements of currently manufactured snowmobiles, and shall not require extensive modifications to the existing vehicle superstructure. All component and pcrforrnancc spa~fic~ions shall be such that they meet a minimum factor of safety of 1.2 above the CAIIClllC anticipated service conditions. The system shall in no way inhibit the safe opcration of thesnowmobile under normal snowmobiling conditions.
5.0 Possible Design Solutions A number of possible design solutions were analyzed to determine their suitability for incorporation in thc Snowmobile Floatation System. The possibilities are discussed in the following sections.
5.1 Floatation Methods Two methods of floatation were considered for the system: that of fixed shape floats and that of flexible inflatable floats or floatation bags. Prelirninary calculations indicated that the volume of water that was requircd to be displaced in order toprovide floatation for the snowmobile and riders was such that it would make fixed shape floats impractical for regular snowmobile operaion. Innatable floats or would allow for compact storage within the e~isting snowmobile structure until their requirement at which point they could be infl~tecl This method of floatation would also prove to be reasonably light when co",pared to a rigid float system. A drawback to inflatable floats would be their susccptibility to tears and leakage. However. this potential problem could be addressed through proper choice of materials.
5.2 Inflation Means For the inflatable float design a means of providing rapid inflation to the floatation bags is required. Two existing technologies where investigated for accomplishing this.
Compressed gas inflaion canisters are routinely used for the inflation of life rafts pasonal floataion devices (PFD s) and other marine safety equipment. The gas typically used is Carbon Dioxide (C02) and is usually mixed with a small portionNitrogen gas (N2) to help maintain flow rates under cold te",pe.~ture conditions.
Inflation times for compressed gas inflator systems are in the order of seconds to l O s of seconds depending on system sizes. Compressed gas inflator technology has been in common use in North America since 1930 and hence benefits from a wide selecion of standard components.
P~lotcchnic gas inflator systems have rccently come into cG""non use for automotive air bag applications in the past 5 years. The gas is usually evolved from a vigorous chemical reaction between Sodium Azide and Oxygen. Inflation times are on the order 2142~3 .
of hundredth's of a second for nominal automotive air bag volumes (less that 100litres). In spite of the pyrotechnic inflator's rapid inflation rate, it has thedisadvantage of being very expensive to replace once used. Also, because of the relative newness of this technology, component availability is limited and expensive.
There also remain safety concerns with this technology in the areas of accidental ignition and high gas ten,~ d~llres.
In comparing these two methods of inflation for the Snowmobile Floatation System, the major factors that were considered were the size requirements and the method of activation. A compressed gas system would easily lend it self to both manual andautomatic (electric) activation, due to the nature of existing valve components. A
pyrotechnic inflator is usually ignited electrically, and hence it may prove difficult to incorporate a manual release. It would however, re~uire less storage space on the snowmobile and would not require the routing of the gas distribution hoses required for a compressed gas system.
S.3 Float Location Float locations were considered based available space for stowage, and the ability of the location to provide buoyancy stability for the snowmobile system in the water.
The first layout considered incorporated a floatation bag in the rear seat storage compartment, to support the rear of the snowmobile. Along with this would be twobags positioned on each side of the lower belly pan irnmediately above the rear edges of the skis. This configuration would provide stability from the three point support, and should fit in within the space restrictions of the average snowmobile. A potential drawback of this layout is the relatively high mounting position of the rear bag. This may permit the rear of the snowmobile to sit too low in the water, whereby allowing the riders to get wet.
The second layout exarnined, consisted of two tube-shaped floats fixed under each of the snowmobile's footrests. These tubes would support the rear portion of the system weight, as well as provide lateral stability due to the width of the tube spacing. A third float would be affixed to the front of the belly pan, under the leading edge of the cowling. This float would take the front portion of the weight. This arrangementwould have the advanta~e of having the floats positioned low enough to keep the ~lq26A3 snowmobile sufficiently above the water Icvel. A potential drawback of having the two rear floats affixed to the underside of the footrests. is their susceptibility to damage when traversing rough tcrrain. Howcver, protective sheaths could be fashioned from a sufficiently durable material to resist damage.
5.4 Automatic Release Mechanism For the use of inflatable floats, an automatic release mechanism is required to initiate bag deployment in the event of an ice break-through. The release mcchanism must act on a signal from an accident sensor (discussed scp~tely) to trigger the inflation process. Thc design of the automatic rclcase mechanism will dcpend on whcther it is used for a compressed gas inflator or a pyrotechrlic type inflator.
A automatic release mechanism for a co,l.p..,ssed gas inflator could consist of an electric solenoid connected to the squib wire on thc comprcssed gas canister. The squib wire is the wire that is pullcd to initiatc gas flow on standard life raft systems.
The solenoid could be powercd by a 12 V battcry cornmon to many snowmobiles withelectric start. Upon receiving the signal from the accident sensor, the solenoid would energize, whereby pulling the squib wire to start the inflation process.
An automatic release system for a pyrotechnic typc inflator could consist of a battery that would to supply a voltage to the inflator ignitor when given a signal from the accident sensor.
S.S Manual Backup Release Mechanism Ln the event of a snowmobile power system failure or dysfunction of the automatic relcase mechanism, a manual backup release mechanism must be available to allow the operator to initiate inflation. The design of the manual backup releasc mechanism will depend on whether it is uscd for a compressed gas inflator or a pyrotechnic typeinflator.
A manual backup release mcchanism for a col-,~ ssed gas irlflator could consist of an actuator cable, with one end connccted to the canister squib wire, and the other end connccted to a release lever on the snowmobile in~l,ul,~nt panel. Inflation wc ~d be initiated by the operator pulling the relcasc levcr.
~:14~3 A manual backup release mechanism for a pyrotechnic type inflator would be somewhat more difficult to develop than for a compressed gas inflator. Almost all curTently available automotive inflators use an electrically operated igniter. To use a system of this type the manual release mechanism would have to generate a voltage suitable to power the igniter. Recently however some pyrotechnic inflator manufacturers have developed mechanically actuated systems. These may prove to be useful for this application.
5.6 Accident Sensor An accident sensor is re~uired to accurately detect when the snowmobile is sinhng.
The electrical signal output from the sensor will control the operaion of the automatic release mechanism. The sensor should not accidentally initiate inflaion under normal riding condiions.
A sensor that detects the presence of water through moisture or te",~elature measuremcnt is a possibility. Difficulty may be encountered with the reliability of a sensor such as this however. Snowmobiling is so~ti.~cs pe.ro~"~d under wet or slushy conditions. A sensor or this type would have to differentiate between these conditions and an actual sinking.
Another type of sensor that may prove effective is a float type sensor. The action would be similar to a ~L.~etor float mechanism. Water taken in at the beginning of an ice accident would cause the float to rise and actuate a switch. The float would have to be designed to remain unaffected by the inertial loads encountered during normal riding. It would also have to be strategically located to avoid being frozen by snow and ice.
214~643 6.0 Description of the Proposed Design Solution Each of the possible design solutions were considered for their feasibility and practicality for use on a typical production snowrnobile. Preliminary calculations were performed and estimations were made to determine which solutions would be most effective for cost reduction, weight minin~ization, ease of fabrication, reliability. and performance. The chosen solutions presented are tentative only, and may change as the project advances through the construction and testing stages.
6.1 Floatation It was decided to use inflatable floats for the Snowmobile Floatation System as opposed to rigid type floats because of the small storage space required. Rigid floats would be tWO bulky to be of any practical value on a snowmobile.
The fJoatation bags will be fabricated from neoprene and hypalon coated nylon. This material is used commonly in the manufacture of high quality life rafts and will provide excellent resistance to puncture, tears, leakage and degradation due to aging. The material cold vulcanizable, which makes it suitable for hand gluing.
The rear floatation bags will be shaped as tubes when fully infl~ted Prior to inflation.
they will be folded and housed in sealed deployment strips to protect them untilneeded. The deployment strips will be mounted on the snowmobile track tunnel. one under each footrest. Figure 6.1 shows one of the rear floatation tubes, with thedeployment strip and its mounting position.
- ~1 42~3 track tunnel deployrnent ~>\
rear tube Figure 6.1: Rear Floatation Tube The front floatation bag will be roughly rectangular in shapc and will be housed in a deployment container affixed to the inside front of the snowmobile bclly pan. Upon inflation, the bag will deploy frontwards out over the skis to providc floatation to the front end of the snowmobile.
6.2 I ~alion System The col-,pressed gas inflator was chosen over the pyrotechnic type bccause of it's ruggedness, cost effectiveness and availability. A carbon dioxide and nitrogen gas mixture will bc used to maintain suitable inflation tirnes under cold temperature conditions. A co,..p.cssed gas canister will be selected to house the required mass of CO2 gas at a prcssw~ of approximatcly 12.4 MPa. High pressure hoses will bc used tO
connect the gas canister to the floatation bags.
6.3 Release Mechanisms A solenoid operatcd, automatic release mechanism will be used as described in Section 5.4. The power will be derived from a 12 V snowmobile battery that will be charged by the snowmobile engine magneto.
A cable operated, manual backup release mechanism will be provided to allow the operator to initiate inflation by pulling lever or cord on the front console of the snowmobile.
6.4 Accident Sensor The chosen design of the release sensor is that of the float type. It is felt that this is the most promising method of detecting a sinking snowmobile. In ordcr to prevent the sensor from being fouled by snow and ice, it is proposed to mount it just inside of the lower belly pan, close to the exhaust pipe exit hole in the cowling. This hole in the cowling is one of the first areas that water will enter when the snowmobile starts to sink. The heat from the exhaust pipe should prevent any buildup of ice in the sensor.
The sensor will likely consist of a light wcight plastic or cork float mounted on a lever of a micro switch. Lightweight springs will provide forces against the float to prevent activation of the switch under inertial loading, but will be overcome when the float is surrounded by water due to the buoyant forces.
2 ~ 4 ~! 6 4 3 ,.~
1.0 Test Snowmobile For System Prototype The design of thc Snowmobile Floatation System is to be based on meeting the requirements of typical modern snowmobile. A tcst snowmobile has been selected that suitably represents the style and layout of currently available machines. The model is a 1988 Arctic Cat El Tigre 5000.
The Arctic Cat snowmobile has a mass of approximately 230 kg. and has the seating space for 2 riders. It is powered by a 49 kW, 2-cycle, liquid cooled engine. The front ski stance is approximately 94 cm and the track width is 40 cm. Front suspension is provided by a coil-over-shock A-aIm system, yielding approximately 15 cm of vertical travel. The rear suspension is of the slide rail type and provides approximately 17 cm of travel.
This machine will be used for testing the prototype Snowmobile Floatation System.
Hence, it will be used for detern~ining design pa-dlllct~.s such as weight, centres of gravity, and component packaging space.
2~ A26~ 3 8.0 Calculation of System Parameters 8.1 Determination of Snowmobile Centre of Gravity Jhe centre of gravity of the test snowmobile for the prototypc snowmobile floatation system is requured to properly size and locate the floatation bags for buoyancy stability. The centre of gravity location was determincd by measurement in longitudinal, transverse and vertical dircctions, under three loading cases. Load case 1 was the snowmobile with no rider weight, load case 2 was the snowmobile with an operator, and load case 3 was the snowmobile with an operator and a passenger. The three load cases are intended to yield the centre of gravity locations of the snowmobile system under typical operating conditions.
8.1.1 Longitudinal and Transverse Direction Measurement The location of the snowmobile centre of gravity in the longitudinal and transverse directions was measured using weight scales placed at threc locations under the chassis. Two scales were used at the front, placcd directly undcr thc suspcnsionupright of each ski. A third scale was placed at the rear of thc snowmobile, centred under the grab bar behind the seat cushion. The distancc betwccn the scales from front to back was measured to be 210.8 cm.
Upon meas,lre",ent of the three load cases, it was observed that the readings of the front two scales were nearly equal to one another. This suggested that the centre of gravity in thc transvcrsc direction was located approximately along the center line of the snowmobile, which is c~ d because of geometric symmetry about this line.
In load case 2. the operator mass uscd was 87 kg. In load case 3, the operator mass uscd was 8~ kg~ and the passenger mass was 57 kg. The results of the measule..,~nts are presented in Table 8.1 . The readings of the front scales arecombined in each load case.
214%~3 Load Case FrontScale Rear Scale Total Wei~ht (N) Wei~ht (N) Weiyht (N) snowmobile only 1566 757 2323 snowmobile + 1976 1202 3178 operator sn~ ~bile + 2083 1606 3689 operator ~ passen~er Table 8.1: Weight Distributions The measured weights and the distance between the scales can be used to find thelocation of the centre of gravity for cach load case through equilibrium analysis.
The centre of gravity locaion is measured relative to the longitudinal location of the front weight scales (the position of the front suspension upright). By summing moments about this point~ the location of the centre of gravity is found;
x = W~s x D ( I ) here; XCG is the distance of the longinldin~l centre of gravity behind the front suspcnsion upright WRS is the weight measured by the rear scale D is the distance bctwcen the front and rear scales Wr is the total measured weight of the three scales The results of the calculations using equation(l) are summarized in Table 8.2.
Samplc Calculations are provided in Appendix B.
2~4~
Load Case xr~ (cm) snowmobile onl y 68.7 snowmobile + 79.8 operator snowmobile + 91.7 operator + rider Table 8.2: Location of Longitudinal Centres of Gravity 8.1.2 Vertical Direction Measurement The location of the centre of gravity of the snowmobile in the ver~cal directionwas measured by swinging the snowmobile as a pendulum and measuring the period of swing about two different pivot points. This method was chosen becauseof its ability to easily accommodate the riders in the measu,c-,lcnt process.
The period of a physical pendulum for small angles of swing is given by [4];
- T=2~rt ~"gd (2) where; T is the period of swing is the rotational inertia of the pendulum about an axis through the pivot M is the mass of the pendulum g is the acceleration of gravity t is the distance from the pivot to the centre of gravity of the pendulum By using the parallel axis theorem, eqn.(l) may be rearranged and solved for therotational inertia of the pendulum about its centre of gravity IG;
IG = 4~ 2 ~ Md (3) 21426~3 .
lf p;endulum is swung about two different pivot points, then two equations can be wrirten for IG and equated to solve for the distance from one of the pivots tO ~he centre of gravity of the pendulum;
4~r 2~d2 _ T2g~d ~r 2~d - (T~2 - T22 ~g (4) where; d, p is the distance from the lower pivot to the centre of gravity of the pendulurn ~d is the distance between the pivots T, is the period of swing about the lower pivot T2 is the period of swing about the upper pivot A complete derivation of e~n.(4) is given in Appendix A. Refer to Figure 8.1 for a diagram of the physical pendulum swung about two different pivot points.
.~"
pivot 2 ~ t pivot I ~.
d, ,. ~ 'I _ .
.~
~' Figure 8.1: Pivot and C of G locations of a Physical Pendulum A cradle systcm was constructed to facilitate the swinging of the test snowmobile as a physical pendulum. A support platforrn on which to place the snowmobile 214~6~3 was fabricated fiom a 4`x8' sheet of plywood, 0.5" thick. Two 2"x4"
reinfor~e,l,cnt ribs were affixed transverscly to either end. A pivot beam formed from 3" angle steel with welded pivot eyelets was secured overhead. 0.25" dia.
rope was tied from each corner of the platform to the one of the pivot eyelets to form a cradle. Slip knots were incorporated in each rope length to allow pivot length adjustment and platform leveling. The snowmobile was placed along the long axis of the platform and centred. A leveling procedure was carried out at each of the two pivot lengths to ensure equal weight distribution. Refer to Figure 8.2 for a schemaic of the cradle system.
~ \
Figure 8.2: Cradle System The snowmobile and cradle system was swung at two different pivot heights under the same three loading conditions as in the longitudinal and transverse direcionmeasurcment. The operator and passcnger masscs wcrc 68 and 73 kg rcspectively.
The hcight of pivot 1 was 232.4 cm, mcasured fTom thc top surface of the platform to the pivot axis. The hcight of pivot 2 was 285.8 cm, mcasured in thc same manncr. Oscillation over an arc of approximately 5 was initiated by hand. The timc for 50 cyclcs was mcasurcd with a stopwatch and rccordcd for cach case.
This time was subsequently divided by 50 to obtain an accurate value for the period of swing. Thc results of the test are summarized in Tablc 8.3 ~4~3 Pivot I Pivot 2 Load Case Time for 50 Period of Time for 50 Period of Cycles (s) Swin~ (s) Cycles (s) Swin~ (s) S.~o~ objle only 143.6 2.872 161.9 3.238 Snowmoblie +
Operator 141.8 2.836 160.0 3.200 Snowmobile +
Operator 1 141.0 2.820 159.0 3.180 Pas~_r.~r Table 8.3: R~sults of Pendulum Swing Te~st The measured periods of swing were then used with equation (4) to calculate the distance of the pendulum centre of gravity below pivot 1, for each load case. The pendulum is taken to be comprised of the snowmobile system (snowmobile plus any riders) and the cradle system. In order to find the distance of the centre of gravity of the snowmobile system below pivot 1, the effect of the cradle must besubtracted from the pendulum result. The distances of the ccntres of gravity of the pendulum, snowmobile system, and cradle system below pivot 1 are related as follows:
Wpd, p = Wsd~ s + Wcdl.c ( ) where; Wp is the weight of the pendulum d, p is the distance of the centre of gravity of the pendulum below pivot I
Ws is the weight of snowmobile sysum d, s is the distance of the centre of gravity of the snowmobile system below pivot l Wc is the weight of cradle system d, c is the distance of the centre of gravity of the cradle system below pivot 1 The cradle system weight was measured to be 290.4 N and was taken to have its centre of gravity located at the centre of the plywood platform (the mass of thethin ropes were considered to bc ncgligible). The distance of the centre of the plywood platform from pivot I was measured to be 233.0 cm.
21 4~643 Using the calculated centre of gravity of the pendulum, the centre of gravity was deterrr~ined for each snowmobile system by rearranging and solving equation (5) This distance was then subtracted from the distance of the platform surface below pivot 1 (232.4 cm), to give the height of the centre of gravity of each snowmobile system above the platform (ZCG)- The results of the calculations are presented in Table 8.4. Sample calculations are provided in Appendix B.
Load Case Zfr. (cm) snowmobile onlv 18.7 snowmobile + 29.4 operator snowmobile + 36.2 operator + rider Table 8.4: Centre of Gravity Height 8.2 Buoyancy Calculations According to the American Boat and Yacht Council [5], the maximum allowable floated weight of the Snowmobile Floatation System should be given by-W = O. 75D (6) Where: W is the maximum floated weight [N
D iS equal to 9.79Vand V is the floatation bag volume [L]
Eqn. (6) can be rearranged to solve for V. For a designed floated weight of 3770Newtons (snowmobile and 2 riders), the required total floatation bag volume is calculated to be approximately 500 L. Refer to Appendix B for sample calculations.
214~643 8.3 Stability Calculations 83.1 Determination of Front and Rear Floatation Bag Volumes This calculation was performed using the centre of gravity position for the single rider load case. This position represcnts the most common condition. By perforrning a moment balance about the centre or gravity of the snowmobile system, the front and rear bag volumes are related by:
VR = FR = dF (7) VF FF dR
where; VR is the rcar bag volume VF is the front bag volume FR is the rear bag buoyant force FF is the front bag buoyant force dR iS the distance from the CofG to the rear bag centre of volume dF iS the distance from the CofG to the front bag centre of volume The total volume of the front and rear bags is 500 L. From the above two relationships, the front and rear bag volumes were calculated to bc 125 and 375 L
respectively. Refer to sample calculations for these volumes in Appendix B. The Rear bag volurne will be divided equally between two bags on either side of the snowmobile.
8.3.2 Calculation of Snowmobile Metacentric Height The calculation of the snowmobile metacentric height is performcd for the load case of the two riders, as this yields the highest vertical centre of gravity distance.
Thc cross section of the proposed floatation bags can bc approximated by two circles, representing the rear floatation tubes, mounted on either side of the track tunnel, and a rectangular section, represcnting the shape of the front floatation bag mounted to the front of the snowmobile cowling. These cross scctions and their approximate relative mounting positions in relation to the centre of gravity location on the snowmobile are~ shown in Figure 8.3.
21426~3 ., C of G waterline \ rear float front float tube sectlon tube sectlon Figure 8.3: Floatation Bag Cross Section The diameter of the rear tubes is approximately 50 cm and the centre distance between them is approximately 130 cm. The front bag profile is approximately 100 cm wide by 50 cm high. For simplification, the combined submerged cross section of the rear and front bags can be approximated as a rectangle of length 2L=178 cm and a height of H=38 cm. Refer to Figure 8.4.
C of G
Figure 8.4: Simplified Floatation Bag Cross Section 2t~2~3 By following ~nite's procedure 16] for an approximate metacentric height calculation. the cross sec~on is tilted by a small angle and the resulting shift in the ccntre of buoyancy (B') is determined. The resulting metacentric height is givenby:
MB- 3H - 3 (8) Using this relationship and the dimensions L and H of the sirnplified rectangular cross section, the metacentric height of the snowmobile with 2 riders was found to be 50.S cm. Because this is a positive quantity, the metacentre occurs above thecentre of gravity. and the snowmobile system wi~l be stable when floating in thewater.
8.4 Calculation of Required Mass of C02 Gas The re~uired mass of C2 gas can be calculated ~y finding the specific volume of the gas under the extreme of the operation conditions, and dividing this into the total required volume of the floatation bags.
The extreme conditions expected will be an ambient te.,lp~raiture of -40 C and a bag pressure of 2 psig (13.8 KPa). From Raznjevic's thermodynamic plo~e-~y charts ofCO~ [7], the specific volume of CO2 that corresponds to these condiions is about 420 L/kg. For a total floataion bag volume of 500 L, this corresponds to a required mass of CO, of 1.2 kg. Refer to the samplc calculations in Appendix B.
85 Calculation of C02 Canister Volume i The canistcr will be sized to house 1.2 kg of CO2 at a tcmperature of 30 C and a pressure of 1700 psig (12.4 MPa). From Raznjcvic's thermodynamic property chartsof CO2 [7], the specific volume of CO2 that corresponds to these conditions is about 1.5 L/kg. From this, a requircd canister volume of 1.8 L is calculated. Refer to the sample calculations presentcd in Appendix B.
,42~q3 8.6 Intlation Time Calculation Thc inflation time of the floatation bags is predicted by performing a blowdown time calculation on the CO, canister. The process can be approximated by makin~ a number of assumptions:
1) The stagnation pressure of the CO2 in the canister is initially at 1700 psig (12.4 MPa) and decreascs during the blowdown process.
2) The stagnation te.n~ dture of the CO2 in the canister is initially 0 C (273 K) and remains constant during the blowdown process.
3) The CO2 behaves as an ideal gas 4) The nozzle cxit pressure is 18.7 psia (129 KPa) The specific heat ratio of CO2 is 1.30 [6]. For a sonic throat, the maximum mass flow rate for the ~as will be given by [61:
PA-m~ =0.6673~ (9) For a nozzle of diameter 6.2S mm, the maximum mass flow rate will be 1.154 kgls.Refer to the sample calcu~ations presented in Appendix B. This represents the mass flow rate at the start of the blowdown process. As the stagnation pressure reduces due to the loss of CO2 mass, the mass flow rate wi~l decrease. To determine the blowdown time, a control volume analysis is performed on the canister to set up a differential equation relating pressure to time. A mass flow balance gives:
d dt (pOv~)+m~l = O (10) where; P RTo by substituting the mass flow rate given by e~n (9) and separating, J dPo = _0-66 2 ~ dt (11 ~I4264 3 after integration, 0.~72~
Po(t) = PO(O)e ~ (12) This equation can be solved for the timc required to drop to a given pressure PO(t). By selecting this pressure to be the minimum pressurc required for sonic flow (236.4 KPa), and using canister volume of 1.85 L, the blowdown time is deterrr~ined to be 1.53 seconds. Refer to the sample ca~culations presented in Appendix B.
~ 2142~43 References [ I ] MTO, "Ont~rio Road Safety Annual Repon, 1992", Ministry of Transportation.Ontario, Scction 6e pg 50.
[2] RLSSC, "The Ontario Drowning Report SL"th Edition",Tbe Royal Life Saving Society Canada, Ontario Branch, pp 4,8, 1992.
[3] RLSSC, "Thc National Drowning Report Third Edition", Tbe Royal Life Sa~ing Society Canada, pp 2-3, 1992.
[4] Hibbeler, R.C.,FnFineerin~ Mechanics - Statics and Dyn~nics 5th ed., Macmillan Publications, pg 540, 1990 [S] Hubbard, D, Com~lete Book of Inflatable Bo~ts. Western Marine Enterprises lnc., Ventura, California, pg 243, 1980.
[6] White, F.M., Fluid Mechanics, McGraw-Hill Inc., Second Edition, 1986.
5.1 Floatation Methods Two methods of floatation were considered for the system: that of fixed shape floats and that of flexible inflatable floats or floatation bags. Prelirninary calculations indicated that the volume of water that was requircd to be displaced in order toprovide floatation for the snowmobile and riders was such that it would make fixed shape floats impractical for regular snowmobile operaion. Innatable floats or would allow for compact storage within the e~isting snowmobile structure until their requirement at which point they could be infl~tecl This method of floatation would also prove to be reasonably light when co",pared to a rigid float system. A drawback to inflatable floats would be their susccptibility to tears and leakage. However. this potential problem could be addressed through proper choice of materials.
5.2 Inflation Means For the inflatable float design a means of providing rapid inflation to the floatation bags is required. Two existing technologies where investigated for accomplishing this.
Compressed gas inflaion canisters are routinely used for the inflation of life rafts pasonal floataion devices (PFD s) and other marine safety equipment. The gas typically used is Carbon Dioxide (C02) and is usually mixed with a small portionNitrogen gas (N2) to help maintain flow rates under cold te",pe.~ture conditions.
Inflation times for compressed gas inflator systems are in the order of seconds to l O s of seconds depending on system sizes. Compressed gas inflator technology has been in common use in North America since 1930 and hence benefits from a wide selecion of standard components.
P~lotcchnic gas inflator systems have rccently come into cG""non use for automotive air bag applications in the past 5 years. The gas is usually evolved from a vigorous chemical reaction between Sodium Azide and Oxygen. Inflation times are on the order 2142~3 .
of hundredth's of a second for nominal automotive air bag volumes (less that 100litres). In spite of the pyrotechnic inflator's rapid inflation rate, it has thedisadvantage of being very expensive to replace once used. Also, because of the relative newness of this technology, component availability is limited and expensive.
There also remain safety concerns with this technology in the areas of accidental ignition and high gas ten,~ d~llres.
In comparing these two methods of inflation for the Snowmobile Floatation System, the major factors that were considered were the size requirements and the method of activation. A compressed gas system would easily lend it self to both manual andautomatic (electric) activation, due to the nature of existing valve components. A
pyrotechnic inflator is usually ignited electrically, and hence it may prove difficult to incorporate a manual release. It would however, re~uire less storage space on the snowmobile and would not require the routing of the gas distribution hoses required for a compressed gas system.
S.3 Float Location Float locations were considered based available space for stowage, and the ability of the location to provide buoyancy stability for the snowmobile system in the water.
The first layout considered incorporated a floatation bag in the rear seat storage compartment, to support the rear of the snowmobile. Along with this would be twobags positioned on each side of the lower belly pan irnmediately above the rear edges of the skis. This configuration would provide stability from the three point support, and should fit in within the space restrictions of the average snowmobile. A potential drawback of this layout is the relatively high mounting position of the rear bag. This may permit the rear of the snowmobile to sit too low in the water, whereby allowing the riders to get wet.
The second layout exarnined, consisted of two tube-shaped floats fixed under each of the snowmobile's footrests. These tubes would support the rear portion of the system weight, as well as provide lateral stability due to the width of the tube spacing. A third float would be affixed to the front of the belly pan, under the leading edge of the cowling. This float would take the front portion of the weight. This arrangementwould have the advanta~e of having the floats positioned low enough to keep the ~lq26A3 snowmobile sufficiently above the water Icvel. A potential drawback of having the two rear floats affixed to the underside of the footrests. is their susceptibility to damage when traversing rough tcrrain. Howcver, protective sheaths could be fashioned from a sufficiently durable material to resist damage.
5.4 Automatic Release Mechanism For the use of inflatable floats, an automatic release mechanism is required to initiate bag deployment in the event of an ice break-through. The release mcchanism must act on a signal from an accident sensor (discussed scp~tely) to trigger the inflation process. Thc design of the automatic rclcase mechanism will dcpend on whcther it is used for a compressed gas inflator or a pyrotechrlic type inflator.
A automatic release mechanism for a co,l.p..,ssed gas inflator could consist of an electric solenoid connected to the squib wire on thc comprcssed gas canister. The squib wire is the wire that is pullcd to initiatc gas flow on standard life raft systems.
The solenoid could be powercd by a 12 V battcry cornmon to many snowmobiles withelectric start. Upon receiving the signal from the accident sensor, the solenoid would energize, whereby pulling the squib wire to start the inflation process.
An automatic release system for a pyrotechnic typc inflator could consist of a battery that would to supply a voltage to the inflator ignitor when given a signal from the accident sensor.
S.S Manual Backup Release Mechanism Ln the event of a snowmobile power system failure or dysfunction of the automatic relcase mechanism, a manual backup release mechanism must be available to allow the operator to initiate inflation. The design of the manual backup releasc mechanism will depend on whether it is uscd for a compressed gas inflator or a pyrotechnic typeinflator.
A manual backup release mcchanism for a col-,~ ssed gas irlflator could consist of an actuator cable, with one end connccted to the canister squib wire, and the other end connccted to a release lever on the snowmobile in~l,ul,~nt panel. Inflation wc ~d be initiated by the operator pulling the relcasc levcr.
~:14~3 A manual backup release mechanism for a pyrotechnic type inflator would be somewhat more difficult to develop than for a compressed gas inflator. Almost all curTently available automotive inflators use an electrically operated igniter. To use a system of this type the manual release mechanism would have to generate a voltage suitable to power the igniter. Recently however some pyrotechnic inflator manufacturers have developed mechanically actuated systems. These may prove to be useful for this application.
5.6 Accident Sensor An accident sensor is re~uired to accurately detect when the snowmobile is sinhng.
The electrical signal output from the sensor will control the operaion of the automatic release mechanism. The sensor should not accidentally initiate inflaion under normal riding condiions.
A sensor that detects the presence of water through moisture or te",~elature measuremcnt is a possibility. Difficulty may be encountered with the reliability of a sensor such as this however. Snowmobiling is so~ti.~cs pe.ro~"~d under wet or slushy conditions. A sensor or this type would have to differentiate between these conditions and an actual sinking.
Another type of sensor that may prove effective is a float type sensor. The action would be similar to a ~L.~etor float mechanism. Water taken in at the beginning of an ice accident would cause the float to rise and actuate a switch. The float would have to be designed to remain unaffected by the inertial loads encountered during normal riding. It would also have to be strategically located to avoid being frozen by snow and ice.
214~643 6.0 Description of the Proposed Design Solution Each of the possible design solutions were considered for their feasibility and practicality for use on a typical production snowrnobile. Preliminary calculations were performed and estimations were made to determine which solutions would be most effective for cost reduction, weight minin~ization, ease of fabrication, reliability. and performance. The chosen solutions presented are tentative only, and may change as the project advances through the construction and testing stages.
6.1 Floatation It was decided to use inflatable floats for the Snowmobile Floatation System as opposed to rigid type floats because of the small storage space required. Rigid floats would be tWO bulky to be of any practical value on a snowmobile.
The fJoatation bags will be fabricated from neoprene and hypalon coated nylon. This material is used commonly in the manufacture of high quality life rafts and will provide excellent resistance to puncture, tears, leakage and degradation due to aging. The material cold vulcanizable, which makes it suitable for hand gluing.
The rear floatation bags will be shaped as tubes when fully infl~ted Prior to inflation.
they will be folded and housed in sealed deployment strips to protect them untilneeded. The deployment strips will be mounted on the snowmobile track tunnel. one under each footrest. Figure 6.1 shows one of the rear floatation tubes, with thedeployment strip and its mounting position.
- ~1 42~3 track tunnel deployrnent ~>\
rear tube Figure 6.1: Rear Floatation Tube The front floatation bag will be roughly rectangular in shapc and will be housed in a deployment container affixed to the inside front of the snowmobile bclly pan. Upon inflation, the bag will deploy frontwards out over the skis to providc floatation to the front end of the snowmobile.
6.2 I ~alion System The col-,pressed gas inflator was chosen over the pyrotechnic type bccause of it's ruggedness, cost effectiveness and availability. A carbon dioxide and nitrogen gas mixture will bc used to maintain suitable inflation tirnes under cold temperature conditions. A co,..p.cssed gas canister will be selected to house the required mass of CO2 gas at a prcssw~ of approximatcly 12.4 MPa. High pressure hoses will bc used tO
connect the gas canister to the floatation bags.
6.3 Release Mechanisms A solenoid operatcd, automatic release mechanism will be used as described in Section 5.4. The power will be derived from a 12 V snowmobile battery that will be charged by the snowmobile engine magneto.
A cable operated, manual backup release mechanism will be provided to allow the operator to initiate inflation by pulling lever or cord on the front console of the snowmobile.
6.4 Accident Sensor The chosen design of the release sensor is that of the float type. It is felt that this is the most promising method of detecting a sinking snowmobile. In ordcr to prevent the sensor from being fouled by snow and ice, it is proposed to mount it just inside of the lower belly pan, close to the exhaust pipe exit hole in the cowling. This hole in the cowling is one of the first areas that water will enter when the snowmobile starts to sink. The heat from the exhaust pipe should prevent any buildup of ice in the sensor.
The sensor will likely consist of a light wcight plastic or cork float mounted on a lever of a micro switch. Lightweight springs will provide forces against the float to prevent activation of the switch under inertial loading, but will be overcome when the float is surrounded by water due to the buoyant forces.
2 ~ 4 ~! 6 4 3 ,.~
1.0 Test Snowmobile For System Prototype The design of thc Snowmobile Floatation System is to be based on meeting the requirements of typical modern snowmobile. A tcst snowmobile has been selected that suitably represents the style and layout of currently available machines. The model is a 1988 Arctic Cat El Tigre 5000.
The Arctic Cat snowmobile has a mass of approximately 230 kg. and has the seating space for 2 riders. It is powered by a 49 kW, 2-cycle, liquid cooled engine. The front ski stance is approximately 94 cm and the track width is 40 cm. Front suspension is provided by a coil-over-shock A-aIm system, yielding approximately 15 cm of vertical travel. The rear suspension is of the slide rail type and provides approximately 17 cm of travel.
This machine will be used for testing the prototype Snowmobile Floatation System.
Hence, it will be used for detern~ining design pa-dlllct~.s such as weight, centres of gravity, and component packaging space.
2~ A26~ 3 8.0 Calculation of System Parameters 8.1 Determination of Snowmobile Centre of Gravity Jhe centre of gravity of the test snowmobile for the prototypc snowmobile floatation system is requured to properly size and locate the floatation bags for buoyancy stability. The centre of gravity location was determincd by measurement in longitudinal, transverse and vertical dircctions, under three loading cases. Load case 1 was the snowmobile with no rider weight, load case 2 was the snowmobile with an operator, and load case 3 was the snowmobile with an operator and a passenger. The three load cases are intended to yield the centre of gravity locations of the snowmobile system under typical operating conditions.
8.1.1 Longitudinal and Transverse Direction Measurement The location of the snowmobile centre of gravity in the longitudinal and transverse directions was measured using weight scales placed at threc locations under the chassis. Two scales were used at the front, placcd directly undcr thc suspcnsionupright of each ski. A third scale was placed at the rear of thc snowmobile, centred under the grab bar behind the seat cushion. The distancc betwccn the scales from front to back was measured to be 210.8 cm.
Upon meas,lre",ent of the three load cases, it was observed that the readings of the front two scales were nearly equal to one another. This suggested that the centre of gravity in thc transvcrsc direction was located approximately along the center line of the snowmobile, which is c~ d because of geometric symmetry about this line.
In load case 2. the operator mass uscd was 87 kg. In load case 3, the operator mass uscd was 8~ kg~ and the passenger mass was 57 kg. The results of the measule..,~nts are presented in Table 8.1 . The readings of the front scales arecombined in each load case.
214%~3 Load Case FrontScale Rear Scale Total Wei~ht (N) Wei~ht (N) Weiyht (N) snowmobile only 1566 757 2323 snowmobile + 1976 1202 3178 operator sn~ ~bile + 2083 1606 3689 operator ~ passen~er Table 8.1: Weight Distributions The measured weights and the distance between the scales can be used to find thelocation of the centre of gravity for cach load case through equilibrium analysis.
The centre of gravity locaion is measured relative to the longitudinal location of the front weight scales (the position of the front suspension upright). By summing moments about this point~ the location of the centre of gravity is found;
x = W~s x D ( I ) here; XCG is the distance of the longinldin~l centre of gravity behind the front suspcnsion upright WRS is the weight measured by the rear scale D is the distance bctwcen the front and rear scales Wr is the total measured weight of the three scales The results of the calculations using equation(l) are summarized in Table 8.2.
Samplc Calculations are provided in Appendix B.
2~4~
Load Case xr~ (cm) snowmobile onl y 68.7 snowmobile + 79.8 operator snowmobile + 91.7 operator + rider Table 8.2: Location of Longitudinal Centres of Gravity 8.1.2 Vertical Direction Measurement The location of the centre of gravity of the snowmobile in the ver~cal directionwas measured by swinging the snowmobile as a pendulum and measuring the period of swing about two different pivot points. This method was chosen becauseof its ability to easily accommodate the riders in the measu,c-,lcnt process.
The period of a physical pendulum for small angles of swing is given by [4];
- T=2~rt ~"gd (2) where; T is the period of swing is the rotational inertia of the pendulum about an axis through the pivot M is the mass of the pendulum g is the acceleration of gravity t is the distance from the pivot to the centre of gravity of the pendulum By using the parallel axis theorem, eqn.(l) may be rearranged and solved for therotational inertia of the pendulum about its centre of gravity IG;
IG = 4~ 2 ~ Md (3) 21426~3 .
lf p;endulum is swung about two different pivot points, then two equations can be wrirten for IG and equated to solve for the distance from one of the pivots tO ~he centre of gravity of the pendulum;
4~r 2~d2 _ T2g~d ~r 2~d - (T~2 - T22 ~g (4) where; d, p is the distance from the lower pivot to the centre of gravity of the pendulurn ~d is the distance between the pivots T, is the period of swing about the lower pivot T2 is the period of swing about the upper pivot A complete derivation of e~n.(4) is given in Appendix A. Refer to Figure 8.1 for a diagram of the physical pendulum swung about two different pivot points.
.~"
pivot 2 ~ t pivot I ~.
d, ,. ~ 'I _ .
.~
~' Figure 8.1: Pivot and C of G locations of a Physical Pendulum A cradle systcm was constructed to facilitate the swinging of the test snowmobile as a physical pendulum. A support platforrn on which to place the snowmobile 214~6~3 was fabricated fiom a 4`x8' sheet of plywood, 0.5" thick. Two 2"x4"
reinfor~e,l,cnt ribs were affixed transverscly to either end. A pivot beam formed from 3" angle steel with welded pivot eyelets was secured overhead. 0.25" dia.
rope was tied from each corner of the platform to the one of the pivot eyelets to form a cradle. Slip knots were incorporated in each rope length to allow pivot length adjustment and platform leveling. The snowmobile was placed along the long axis of the platform and centred. A leveling procedure was carried out at each of the two pivot lengths to ensure equal weight distribution. Refer to Figure 8.2 for a schemaic of the cradle system.
~ \
Figure 8.2: Cradle System The snowmobile and cradle system was swung at two different pivot heights under the same three loading conditions as in the longitudinal and transverse direcionmeasurcment. The operator and passcnger masscs wcrc 68 and 73 kg rcspectively.
The hcight of pivot 1 was 232.4 cm, mcasured fTom thc top surface of the platform to the pivot axis. The hcight of pivot 2 was 285.8 cm, mcasured in thc same manncr. Oscillation over an arc of approximately 5 was initiated by hand. The timc for 50 cyclcs was mcasurcd with a stopwatch and rccordcd for cach case.
This time was subsequently divided by 50 to obtain an accurate value for the period of swing. Thc results of the test are summarized in Tablc 8.3 ~4~3 Pivot I Pivot 2 Load Case Time for 50 Period of Time for 50 Period of Cycles (s) Swin~ (s) Cycles (s) Swin~ (s) S.~o~ objle only 143.6 2.872 161.9 3.238 Snowmoblie +
Operator 141.8 2.836 160.0 3.200 Snowmobile +
Operator 1 141.0 2.820 159.0 3.180 Pas~_r.~r Table 8.3: R~sults of Pendulum Swing Te~st The measured periods of swing were then used with equation (4) to calculate the distance of the pendulum centre of gravity below pivot 1, for each load case. The pendulum is taken to be comprised of the snowmobile system (snowmobile plus any riders) and the cradle system. In order to find the distance of the centre of gravity of the snowmobile system below pivot 1, the effect of the cradle must besubtracted from the pendulum result. The distances of the ccntres of gravity of the pendulum, snowmobile system, and cradle system below pivot 1 are related as follows:
Wpd, p = Wsd~ s + Wcdl.c ( ) where; Wp is the weight of the pendulum d, p is the distance of the centre of gravity of the pendulum below pivot I
Ws is the weight of snowmobile sysum d, s is the distance of the centre of gravity of the snowmobile system below pivot l Wc is the weight of cradle system d, c is the distance of the centre of gravity of the cradle system below pivot 1 The cradle system weight was measured to be 290.4 N and was taken to have its centre of gravity located at the centre of the plywood platform (the mass of thethin ropes were considered to bc ncgligible). The distance of the centre of the plywood platform from pivot I was measured to be 233.0 cm.
21 4~643 Using the calculated centre of gravity of the pendulum, the centre of gravity was deterrr~ined for each snowmobile system by rearranging and solving equation (5) This distance was then subtracted from the distance of the platform surface below pivot 1 (232.4 cm), to give the height of the centre of gravity of each snowmobile system above the platform (ZCG)- The results of the calculations are presented in Table 8.4. Sample calculations are provided in Appendix B.
Load Case Zfr. (cm) snowmobile onlv 18.7 snowmobile + 29.4 operator snowmobile + 36.2 operator + rider Table 8.4: Centre of Gravity Height 8.2 Buoyancy Calculations According to the American Boat and Yacht Council [5], the maximum allowable floated weight of the Snowmobile Floatation System should be given by-W = O. 75D (6) Where: W is the maximum floated weight [N
D iS equal to 9.79Vand V is the floatation bag volume [L]
Eqn. (6) can be rearranged to solve for V. For a designed floated weight of 3770Newtons (snowmobile and 2 riders), the required total floatation bag volume is calculated to be approximately 500 L. Refer to Appendix B for sample calculations.
214~643 8.3 Stability Calculations 83.1 Determination of Front and Rear Floatation Bag Volumes This calculation was performed using the centre of gravity position for the single rider load case. This position represcnts the most common condition. By perforrning a moment balance about the centre or gravity of the snowmobile system, the front and rear bag volumes are related by:
VR = FR = dF (7) VF FF dR
where; VR is the rcar bag volume VF is the front bag volume FR is the rear bag buoyant force FF is the front bag buoyant force dR iS the distance from the CofG to the rear bag centre of volume dF iS the distance from the CofG to the front bag centre of volume The total volume of the front and rear bags is 500 L. From the above two relationships, the front and rear bag volumes were calculated to bc 125 and 375 L
respectively. Refer to sample calculations for these volumes in Appendix B. The Rear bag volurne will be divided equally between two bags on either side of the snowmobile.
8.3.2 Calculation of Snowmobile Metacentric Height The calculation of the snowmobile metacentric height is performcd for the load case of the two riders, as this yields the highest vertical centre of gravity distance.
Thc cross section of the proposed floatation bags can bc approximated by two circles, representing the rear floatation tubes, mounted on either side of the track tunnel, and a rectangular section, represcnting the shape of the front floatation bag mounted to the front of the snowmobile cowling. These cross scctions and their approximate relative mounting positions in relation to the centre of gravity location on the snowmobile are~ shown in Figure 8.3.
21426~3 ., C of G waterline \ rear float front float tube sectlon tube sectlon Figure 8.3: Floatation Bag Cross Section The diameter of the rear tubes is approximately 50 cm and the centre distance between them is approximately 130 cm. The front bag profile is approximately 100 cm wide by 50 cm high. For simplification, the combined submerged cross section of the rear and front bags can be approximated as a rectangle of length 2L=178 cm and a height of H=38 cm. Refer to Figure 8.4.
C of G
Figure 8.4: Simplified Floatation Bag Cross Section 2t~2~3 By following ~nite's procedure 16] for an approximate metacentric height calculation. the cross sec~on is tilted by a small angle and the resulting shift in the ccntre of buoyancy (B') is determined. The resulting metacentric height is givenby:
MB- 3H - 3 (8) Using this relationship and the dimensions L and H of the sirnplified rectangular cross section, the metacentric height of the snowmobile with 2 riders was found to be 50.S cm. Because this is a positive quantity, the metacentre occurs above thecentre of gravity. and the snowmobile system wi~l be stable when floating in thewater.
8.4 Calculation of Required Mass of C02 Gas The re~uired mass of C2 gas can be calculated ~y finding the specific volume of the gas under the extreme of the operation conditions, and dividing this into the total required volume of the floatation bags.
The extreme conditions expected will be an ambient te.,lp~raiture of -40 C and a bag pressure of 2 psig (13.8 KPa). From Raznjevic's thermodynamic plo~e-~y charts ofCO~ [7], the specific volume of CO2 that corresponds to these condiions is about 420 L/kg. For a total floataion bag volume of 500 L, this corresponds to a required mass of CO, of 1.2 kg. Refer to the samplc calculations in Appendix B.
85 Calculation of C02 Canister Volume i The canistcr will be sized to house 1.2 kg of CO2 at a tcmperature of 30 C and a pressure of 1700 psig (12.4 MPa). From Raznjcvic's thermodynamic property chartsof CO2 [7], the specific volume of CO2 that corresponds to these conditions is about 1.5 L/kg. From this, a requircd canister volume of 1.8 L is calculated. Refer to the sample calculations presentcd in Appendix B.
,42~q3 8.6 Intlation Time Calculation Thc inflation time of the floatation bags is predicted by performing a blowdown time calculation on the CO, canister. The process can be approximated by makin~ a number of assumptions:
1) The stagnation pressure of the CO2 in the canister is initially at 1700 psig (12.4 MPa) and decreascs during the blowdown process.
2) The stagnation te.n~ dture of the CO2 in the canister is initially 0 C (273 K) and remains constant during the blowdown process.
3) The CO2 behaves as an ideal gas 4) The nozzle cxit pressure is 18.7 psia (129 KPa) The specific heat ratio of CO2 is 1.30 [6]. For a sonic throat, the maximum mass flow rate for the ~as will be given by [61:
PA-m~ =0.6673~ (9) For a nozzle of diameter 6.2S mm, the maximum mass flow rate will be 1.154 kgls.Refer to the sample calcu~ations presented in Appendix B. This represents the mass flow rate at the start of the blowdown process. As the stagnation pressure reduces due to the loss of CO2 mass, the mass flow rate wi~l decrease. To determine the blowdown time, a control volume analysis is performed on the canister to set up a differential equation relating pressure to time. A mass flow balance gives:
d dt (pOv~)+m~l = O (10) where; P RTo by substituting the mass flow rate given by e~n (9) and separating, J dPo = _0-66 2 ~ dt (11 ~I4264 3 after integration, 0.~72~
Po(t) = PO(O)e ~ (12) This equation can be solved for the timc required to drop to a given pressure PO(t). By selecting this pressure to be the minimum pressurc required for sonic flow (236.4 KPa), and using canister volume of 1.85 L, the blowdown time is deterrr~ined to be 1.53 seconds. Refer to the sample ca~culations presented in Appendix B.
~ 2142~43 References [ I ] MTO, "Ont~rio Road Safety Annual Repon, 1992", Ministry of Transportation.Ontario, Scction 6e pg 50.
[2] RLSSC, "The Ontario Drowning Report SL"th Edition",Tbe Royal Life Saving Society Canada, Ontario Branch, pp 4,8, 1992.
[3] RLSSC, "Thc National Drowning Report Third Edition", Tbe Royal Life Sa~ing Society Canada, pp 2-3, 1992.
[4] Hibbeler, R.C.,FnFineerin~ Mechanics - Statics and Dyn~nics 5th ed., Macmillan Publications, pg 540, 1990 [S] Hubbard, D, Com~lete Book of Inflatable Bo~ts. Western Marine Enterprises lnc., Ventura, California, pg 243, 1980.
[6] White, F.M., Fluid Mechanics, McGraw-Hill Inc., Second Edition, 1986.
[7] Raznjevic, K, H~ndbook of Thermodyn~rnic Tables and (~h~nc, pp 382-383, 1978 ~2~3 Appendix A
Derivation of Pendulum Formula F~o~t~t~ r~ ¦c~AjTec oF ~;2AUl7y ¦ ~14~693 'I p ~ c A- r ~t ~ p ~
T ~ T ~gn (2 ~ Sect EQ~ 5 ~ E ~l~r~ Q~ P
PT ~ ~ ~E P~vt)~4~ C ~G
, s ~ Ro~ 10~A~ (~FJ27 ~ O F
7 ~ ~ PF~ a ~ ~ 4 A ~ 5 2046H ~E P~ ~J07 9 ~ G ~ ~ ~" 7 ~ C C ~ A ~ 7 ~ lS ~IJ~ 0~ 7ff~ PFJ~J
fo~2 ~ Plt"S~CAL PE~ ~ s~ G ~B~
2_ ~ / r~r ~7 P~ v ~ ~ Po~r .
7T j~ ~ ~
~ 1 p~c~ t ~r\ d 2_ d, ~D~ N~ 2 ) ~J 7 ~P~ S o F
I = r1T2 d 4~9~
FoR p~ v~S I ~ :
TIZg ~ ~ ~ Iz - ~r,~
F~A-~r~o~ ~YsTE~ ¦ ~5C~ o~u Fo~u ~ 214~64 3 /
or~ p/~2~C~ ~ X I S ~t S~oQF,4t G t ~I d ~ C = I, ~ 2 1~ - TC ~ Z ~ M d 2 E~t~lE I 6~ 5 7 '~ ~7 E ~ c ~, '~
rt 7 ~ ~, 2 = ~ + ~ 2 o~ z ) ~ ~' 9 ~ ~ = T 2 d t 4Tr 2 ~ Z _ d~?) A S~O~
b~t c~ = c(, t ~ O( (C~Zt C~ z- d,) ~ ac~O/,)(o(,~a~ -~,) C~ 2 c~ ot 2 ~n o~ ~sl~
T~Z9 d~ = Tj~ ot, t ~ ( 20~"~c( t rz g ~ t T~? g ~o~ = T,~gc/, ~ 8Tr 2d, ~ 477 a~2 !
~ C 0 4 1 ~ OC ~ o ~ ~ ~ e ~ A ~ c ~, 0 r ~ i ~
2 14 ~
d - I ,Z ~ GJ, g ~T 7 ~ 9 ~ L Y~d 3 ~, 9 - g ~TZ~ G~ 7 ~G~
T~Z~3 ~ d ~ (d~
- ~Tr Z Qd - ( T,Z ~ ) g 214264~
Appendix B
Sample Calculations ,- C ~, 4 ~ c ~ f ~ c ~ ~ 1 2 ~ 4 ~ ~ 4 3 ~
~p~ f C ~ T ~ c ~ ~
, L ~ VC l, -~ J ~ c -rJ r ~ c ~ I ~ ¢~
, C ~ t S_ C l J~ ! 2 ~ C ~ ~ C,~
~h~ ~C;C47(c"J ~ r ~ c ,-~c ~ Ci.
G~ B~ T~t~ f~Zc~ ~rf~ o~ ,.
f ~ f ~
e c + 7 f~A~ ~ 4~E
~ 7 ,~ f 7 ^ ' A ~ ";~ /, 7 ~;
J R ' = l ~ ?
r, ~ Ic ~
7 ~ 7 ~ y ~ I ~ c c- r 2 '3 2 3 ~ ]
~c~ = 68 ~ CC
\J~2~ 1~A I 1~ l ~CT 10 /~J
1~ D 157A~ ~ FR o,~ T~ o~"r~- P~ T G r7 ~/~
~ ~ ~ ~ ? ' 7 /~ r' ~~ L c~
_ G !
_1"c, _ ~ c~ e~
Derivation of Pendulum Formula F~o~t~t~ r~ ¦c~AjTec oF ~;2AUl7y ¦ ~14~693 'I p ~ c A- r ~t ~ p ~
T ~ T ~gn (2 ~ Sect EQ~ 5 ~ E ~l~r~ Q~ P
PT ~ ~ ~E P~vt)~4~ C ~G
, s ~ Ro~ 10~A~ (~FJ27 ~ O F
7 ~ ~ PF~ a ~ ~ 4 A ~ 5 2046H ~E P~ ~J07 9 ~ G ~ ~ ~" 7 ~ C C ~ A ~ 7 ~ lS ~IJ~ 0~ 7ff~ PFJ~J
fo~2 ~ Plt"S~CAL PE~ ~ s~ G ~B~
2_ ~ / r~r ~7 P~ v ~ ~ Po~r .
7T j~ ~ ~
~ 1 p~c~ t ~r\ d 2_ d, ~D~ N~ 2 ) ~J 7 ~P~ S o F
I = r1T2 d 4~9~
FoR p~ v~S I ~ :
TIZg ~ ~ ~ Iz - ~r,~
F~A-~r~o~ ~YsTE~ ¦ ~5C~ o~u Fo~u ~ 214~64 3 /
or~ p/~2~C~ ~ X I S ~t S~oQF,4t G t ~I d ~ C = I, ~ 2 1~ - TC ~ Z ~ M d 2 E~t~lE I 6~ 5 7 '~ ~7 E ~ c ~, '~
rt 7 ~ ~, 2 = ~ + ~ 2 o~ z ) ~ ~' 9 ~ ~ = T 2 d t 4Tr 2 ~ Z _ d~?) A S~O~
b~t c~ = c(, t ~ O( (C~Zt C~ z- d,) ~ ac~O/,)(o(,~a~ -~,) C~ 2 c~ ot 2 ~n o~ ~sl~
T~Z9 d~ = Tj~ ot, t ~ ( 20~"~c( t rz g ~ t T~? g ~o~ = T,~gc/, ~ 8Tr 2d, ~ 477 a~2 !
~ C 0 4 1 ~ OC ~ o ~ ~ ~ e ~ A ~ c ~, 0 r ~ i ~
2 14 ~
d - I ,Z ~ GJ, g ~T 7 ~ 9 ~ L Y~d 3 ~, 9 - g ~TZ~ G~ 7 ~G~
T~Z~3 ~ d ~ (d~
- ~Tr Z Qd - ( T,Z ~ ) g 214264~
Appendix B
Sample Calculations ,- C ~, 4 ~ c ~ f ~ c ~ ~ 1 2 ~ 4 ~ ~ 4 3 ~
~p~ f C ~ T ~ c ~ ~
, L ~ VC l, -~ J ~ c -rJ r ~ c ~ I ~ ¢~
, C ~ t S_ C l J~ ! 2 ~ C ~ ~ C,~
~h~ ~C;C47(c"J ~ r ~ c ,-~c ~ Ci.
G~ B~ T~t~ f~Zc~ ~rf~ o~ ,.
f ~ f ~
e c + 7 f~A~ ~ 4~E
~ 7 ,~ f 7 ^ ' A ~ ";~ /, 7 ~;
J R ' = l ~ ?
r, ~ Ic ~
7 ~ 7 ~ y ~ I ~ c c- r 2 '3 2 3 ~ ]
~c~ = 68 ~ CC
\J~2~ 1~A I 1~ l ~CT 10 /~J
1~ D 157A~ ~ FR o,~ T~ o~"r~- P~ T G r7 ~/~
~ ~ ~ ~ ? ' 7 /~ r' ~~ L c~
_ G !
_1"c, _ ~ c~ e~
- 8 ~ ~ 40~ --( T~ - J2 ) g S e c t 7. 1 7 ~ ~ s -,~, c ~ ~ ~ c ,r ~ ~' L c ~ L C ,~
s3.4 r~l T~ = 2 ~-12 ~ 3~_ d`~ p = ~ 53 ~ 2 _ ~.Z~ s,2 ~ qg~ 2~ V, Z ~ ~3 ~( ~C1~ --(2.~72 CS~ - 3 235~ 81~C~I5 C~ 5 q C~
I
~! S /~r ~ C c . c - H ~ 1 2 C ~' c ~ (; ~ c ~
Pi' ~ L~ r ~ f ~" ~
J B'. .
Y~. c~ c!"s ~ 5~c~ 7 !
J ' ~ F ~ , C ~ C C .; ' c-C~,p = '2 ~5 q ~ l3 , ,V_ S ~ ~ [C ~] I~J S ~ 3 ~ 3 c~ C _- 2 33 0 ~ J~ - 'i 9~
QE~Q~ 6 1~ 6 ~0~ , TO S~L~J~ Fo ~ 5 dl, S - ~p d ~ c ~61~ lS q fc ~3 - 2~0.~t ~A~1 X ~33 0;
~323 ~0 ~1 I S ~ ~L 3 ? ~~
r ~ ~ ( r~ sl 2 1 4~ 5D~ ~ -B r~ f E p ls ~ J CE C~ F l ~
S~'u ~(L E C ~ 7, ~E oF G2AvlTy ,4 C3 ~ T~E
6Q~a (Zc6~l S~B7e/~Cr C~ s Fe~ E
~ t A~c ~ ~ Pt v ~r I -r O ) ~ o f~
sue~f cF ~ ~F ~T ~e~ (23~ c~
2 ~ 2 ~/ ~ rv77 ~ I J
~32 ~ ~ 2 13 7 CCr-~
~CC 18. 7 ~C ~1 (ZGC-C ~ ., t; 1 ~ 2 1 4 2 ~
C ~ (, C ~ ~ r G2 C~ ~ ~ C ~ =~G/~
BA 6 IJ C) L ~' h ~E /~,4) 1~(~ ~-L~ B~ E F~c~1 ~ O ~ G~f T
o 7~ s~ ~C~lL~ cO~ ~ c~ s~57 F~ ~5 C- "JE lJ ~3 't W -- 0.~5 4 ~ ' ~1 I S ~ E ~ f 1~ T ( I . F Q ~ o q- 7 q \/
AJ ~~1 I S !t~ T~ L v~ ~ ~ O f F~ r~ ~ ~ B A 65 I ~ C~
i 2 ~ ~J6 ( ~
V= ~J
0.7S-(q7q) C/v T~ ~ 0~5~6 ~ ~ ~E 16 u T CJ ~ T~t E ~ 5 ~ ' :
~ _ 37 70 [~J]
S o~ 6 :
\~ = 377c r~7 ~6 0.1S ( q~
v~6= ~ / 3 ~Ll ~ ( V`, ) ~ C I( /, A ~ ~ o / ~ O F r 2 C ~ E ~ 2 ~,C 47 ~ O ,u r~ a~J hE5 (~S (~6 ~ U~ c 0~ G t~e --,,,- ~6L
R / ~ C~E ~ PQY~4 ~o~l/~ 6 P~ S~ ,F Fe~`r p QF~ F~o~ ~ B~6s ,4 ~.3.~ d 0 ~ ~o ~
qcc~ 3q~
rf fR
~o~ A B/I~CE C~F ~~ 0~ 7 ~,:
7 q ~ ~R = 3 Ff Ff~,.6 I~~Jc~, Th~ Fe~ R~ u~ c,~
~,2 C ~ P 3Y
3 ~ ~
r /~ E -rT A C ~ ~, e~ G~ ~ h~ ~ s soc L
\l F t ~JL = 5 o CL~
~JF ~ 3 ''1~ - 4 V!f- - 5 oc? CL1 \~f = SC~o ~L-I
~J F -- I Z S ~ F
Z S
U Q. 375 ~L~
~ ~ ~ ( O ~ ~ 6 4 ~ ~
C~L~ 7 (~ ~ c F -~ h~3lL e ,~F ,4C~7QI~
~ F/~ ~T
F'~ 6 r,~ E Pt~ 6~ ~d ~ e~ O F~ ~ f~f ~7 r ~0 CA~ C ~. L A~ E T H ~ hE TA ~ T ~ 1 c /`~ f l 6.t T
7~f~ S-ECT~ G'~
L I L
T~ Q~ ~ sf~ s G~7 /~ '~ E O :
~IC~
3~ 2, ~cQ L = ?9 ~C ~- ~ lt; 3 I
S
3 (3a ) h B = Sa - S
C a ¦ ~1426~3 C~C~T !~ oF R~u !2fr) ~s~ ~F C~'. G~.
T ~ I ~ F ~ I F 5 ~ c L ~ d ~ B A ~, S 7 a ~ pS19 ~ --~C
~ ~s i~ . 6 7~, psi~ x 6 ~ 9~t 6 ~
~SIg~ 5J(3 C~
~c~ v~ r o ~ p I c ~3 ~151~3 _p~ rkp /~ /. /7 kp I C~3 q ~ 0 6 ~
ff?~ c ~A~T ~ C ' @ ~ C C ~ p = ~ p ~c ~,~
~r ~ 420 ~L / ~9~
s~ c~ ~L~
7 ~r ~Zc~ CL ~
~ c _ 1 2 ~9~ ` C~
(C'~ s~ o~v~
C /~ LC ~L 4r~o ~) ~ C 4~J~5~ ~ \lo~ T ~ C~'rA I AJ
` C ~ i7CC~
l~oo cp~ q~s~s~rP~l x Cq f~C6~35~ - iZrf/C~`
~ ~0~ C~1A~r 11 ~J C6~
@ ~r - 3CJ 6 C ~t P ~ /'20 C ~ p~
~iCol C 1 ~ ~ L
,-~, `V~Or <~ r = u~o 2~ 1 Co~
(~L~ )( I 2 cc,.l5~ = / g ~L~ -- /V"~
I
r~ ~f ~~ C~ ~ C J,.~ 7 (~L,~ % ~q 3 7 ~ ~ ~ 7 / ~ E c~ r , ~ c ~ ~ c ~ l c ~~
f~4 7 (C ~~ `/ ~7E ~ C~r ~ ~ ~ r .-' C C ?, C ~ ~J ,~
/~r C ~. ~
I
tl~E ~1~46 ~ ~7 ~ Pe~s ~ R ~ oF I ~ C~
i ~ 7 ~ R l ~ /4, L ~ 2 ~ C~ r.~
l _ ; ~ 6 7 ~ r p~
~ ~ a 1 ~ G ~ 7 Cc~ G ~ s 1~ ~ A~ ~~ 'J'' /-~
C ~ C ~ 2 ~ C 7 ~ ~ ! G ' C C ~ ~J D~ ~ ~ F s 1(~ Z~ t ~,r f7~Z~-'S<~e~ ~s 12q ~p~ c (--c C c~r/ E ~ r ,c ~ G ~ ' , _ ~ 3 <~ r~ _ h-4 ~
~ ; = o ~ u 5 7 ~ r f ~ t () f FCQ ~h~C ~' G ~C ~, ~, ~ p~ rc _ = ~ 3~ L~ PC
c~ 7 c~ ~ 4 ~ -~
A~ ~ASj FCc~ ~ Is .
( 2 ~ ) 'Z ~ L~
r;~ = ~/c7~ pO A~
(R T~' ~, .
7 ~f~ ~ 1V c Z Z ~ h ~ F J~ F~C æ 7 ~_ ~ O z ~ t f~ 6 -¦ ~J _~1J G '2 ~ 1. c- ~ p,' ~ 1 5 o . c c 6 ~ 5 J ~ 7 4 L~
7 ~(. C- As ~ C~J ~ ~1 " . ~o' CG ~ t,-r~ _I gC~ / s~ k ~ B~ ~ L~
S~f ~ CC~?~ c~ ~ t'~
c - ~ C = ~73 ~
L ~ t ~ o ~ /~ r S ~ ~7 ~ f ~ f~f l~ l c ~ Pc~ - s ~s ~ J E ~J ~ 5-r~ _ 12 ~C L~ P~ r i~ fC ~C~S- ~
I
- -~./f ~ ~ rI~ 5S ~ C,C~ R~
7 ~; 7 ~ E B C ~ ~ O ~ ~ ~ ~ C
r~ r ~ - - X ~ 1 5 C C ~ / r~ 6 7 Y / ~ ~r-(~S'l ~ s7 ~ X ~13 ~ k~ )~Z
~rY~ = I. IS4 ~9 /5 TO f(~O ~ 0~ PO~ ~ T(~F ~R T~ ~6~A~!~
P2f S5 ~ ~ ~ 7~ C Q E~ 0~ , 2 4 0 C C~
l2 C~C P~1 ~ PF R Fce ~, A CC~J ~ ~ t, ~ ~
~,1, lL ~ s 15 to~ ~HE ca~
4 A~ 2 -Z 2 ~, V
d (f o VC~ s~ ) t ~l~r~t =
.. 4~,~
~ O __ ~? G '~ f ~ ~ c ,l~ T,~ o ~ 2 1 4 ~ ~ 4 ~
- ~ Sy ~ T~ 7~ o ~ ~'. 6 ~
~ e~ fo = apT~ a.~( ~ey;~ O ~ze~
s;
c ~ 7 2 F~
"~
_ ~ 6672 /4~ (RTo~ I d~
I ~ V~an;sfer t~r~.4T ~J G ~
) e~cp .6~72 A~(RT~ t i*~ r~ t~ e~ (3 ~7Y/~ gq~2 4 a~ exp ~~ ~ S~ tl r P~ o ,, In - ~36 ~ Po7 f~ e,~(23~-/ lZ,~
_ 2. sq f = / s~ ~s~
s3.4 r~l T~ = 2 ~-12 ~ 3~_ d`~ p = ~ 53 ~ 2 _ ~.Z~ s,2 ~ qg~ 2~ V, Z ~ ~3 ~( ~C1~ --(2.~72 CS~ - 3 235~ 81~C~I5 C~ 5 q C~
I
~! S /~r ~ C c . c - H ~ 1 2 C ~' c ~ (; ~ c ~
Pi' ~ L~ r ~ f ~" ~
J B'. .
Y~. c~ c!"s ~ 5~c~ 7 !
J ' ~ F ~ , C ~ C C .; ' c-C~,p = '2 ~5 q ~ l3 , ,V_ S ~ ~ [C ~] I~J S ~ 3 ~ 3 c~ C _- 2 33 0 ~ J~ - 'i 9~
QE~Q~ 6 1~ 6 ~0~ , TO S~L~J~ Fo ~ 5 dl, S - ~p d ~ c ~61~ lS q fc ~3 - 2~0.~t ~A~1 X ~33 0;
~323 ~0 ~1 I S ~ ~L 3 ? ~~
r ~ ~ ( r~ sl 2 1 4~ 5D~ ~ -B r~ f E p ls ~ J CE C~ F l ~
S~'u ~(L E C ~ 7, ~E oF G2AvlTy ,4 C3 ~ T~E
6Q~a (Zc6~l S~B7e/~Cr C~ s Fe~ E
~ t A~c ~ ~ Pt v ~r I -r O ) ~ o f~
sue~f cF ~ ~F ~T ~e~ (23~ c~
2 ~ 2 ~/ ~ rv77 ~ I J
~32 ~ ~ 2 13 7 CCr-~
~CC 18. 7 ~C ~1 (ZGC-C ~ ., t; 1 ~ 2 1 4 2 ~
C ~ (, C ~ ~ r G2 C~ ~ ~ C ~ =~G/~
BA 6 IJ C) L ~' h ~E /~,4) 1~(~ ~-L~ B~ E F~c~1 ~ O ~ G~f T
o 7~ s~ ~C~lL~ cO~ ~ c~ s~57 F~ ~5 C- "JE lJ ~3 't W -- 0.~5 4 ~ ' ~1 I S ~ E ~ f 1~ T ( I . F Q ~ o q- 7 q \/
AJ ~~1 I S !t~ T~ L v~ ~ ~ O f F~ r~ ~ ~ B A 65 I ~ C~
i 2 ~ ~J6 ( ~
V= ~J
0.7S-(q7q) C/v T~ ~ 0~5~6 ~ ~ ~E 16 u T CJ ~ T~t E ~ 5 ~ ' :
~ _ 37 70 [~J]
S o~ 6 :
\~ = 377c r~7 ~6 0.1S ( q~
v~6= ~ / 3 ~Ll ~ ( V`, ) ~ C I( /, A ~ ~ o / ~ O F r 2 C ~ E ~ 2 ~,C 47 ~ O ,u r~ a~J hE5 (~S (~6 ~ U~ c 0~ G t~e --,,,- ~6L
R / ~ C~E ~ PQY~4 ~o~l/~ 6 P~ S~ ,F Fe~`r p QF~ F~o~ ~ B~6s ,4 ~.3.~ d 0 ~ ~o ~
qcc~ 3q~
rf fR
~o~ A B/I~CE C~F ~~ 0~ 7 ~,:
7 q ~ ~R = 3 Ff Ff~,.6 I~~Jc~, Th~ Fe~ R~ u~ c,~
~,2 C ~ P 3Y
3 ~ ~
r /~ E -rT A C ~ ~, e~ G~ ~ h~ ~ s soc L
\l F t ~JL = 5 o CL~
~JF ~ 3 ''1~ - 4 V!f- - 5 oc? CL1 \~f = SC~o ~L-I
~J F -- I Z S ~ F
Z S
U Q. 375 ~L~
~ ~ ~ ( O ~ ~ 6 4 ~ ~
C~L~ 7 (~ ~ c F -~ h~3lL e ,~F ,4C~7QI~
~ F/~ ~T
F'~ 6 r,~ E Pt~ 6~ ~d ~ e~ O F~ ~ f~f ~7 r ~0 CA~ C ~. L A~ E T H ~ hE TA ~ T ~ 1 c /`~ f l 6.t T
7~f~ S-ECT~ G'~
L I L
T~ Q~ ~ sf~ s G~7 /~ '~ E O :
~IC~
3~ 2, ~cQ L = ?9 ~C ~- ~ lt; 3 I
S
3 (3a ) h B = Sa - S
C a ¦ ~1426~3 C~C~T !~ oF R~u !2fr) ~s~ ~F C~'. G~.
T ~ I ~ F ~ I F 5 ~ c L ~ d ~ B A ~, S 7 a ~ pS19 ~ --~C
~ ~s i~ . 6 7~, psi~ x 6 ~ 9~t 6 ~
~SIg~ 5J(3 C~
~c~ v~ r o ~ p I c ~3 ~151~3 _p~ rkp /~ /. /7 kp I C~3 q ~ 0 6 ~
ff?~ c ~A~T ~ C ' @ ~ C C ~ p = ~ p ~c ~,~
~r ~ 420 ~L / ~9~
s~ c~ ~L~
7 ~r ~Zc~ CL ~
~ c _ 1 2 ~9~ ` C~
(C'~ s~ o~v~
C /~ LC ~L 4r~o ~) ~ C 4~J~5~ ~ \lo~ T ~ C~'rA I AJ
` C ~ i7CC~
l~oo cp~ q~s~s~rP~l x Cq f~C6~35~ - iZrf/C~`
~ ~0~ C~1A~r 11 ~J C6~
@ ~r - 3CJ 6 C ~t P ~ /'20 C ~ p~
~iCol C 1 ~ ~ L
,-~, `V~Or <~ r = u~o 2~ 1 Co~
(~L~ )( I 2 cc,.l5~ = / g ~L~ -- /V"~
I
r~ ~f ~~ C~ ~ C J,.~ 7 (~L,~ % ~q 3 7 ~ ~ ~ 7 / ~ E c~ r , ~ c ~ ~ c ~ l c ~~
f~4 7 (C ~~ `/ ~7E ~ C~r ~ ~ ~ r .-' C C ?, C ~ ~J ,~
/~r C ~. ~
I
tl~E ~1~46 ~ ~7 ~ Pe~s ~ R ~ oF I ~ C~
i ~ 7 ~ R l ~ /4, L ~ 2 ~ C~ r.~
l _ ; ~ 6 7 ~ r p~
~ ~ a 1 ~ G ~ 7 Cc~ G ~ s 1~ ~ A~ ~~ 'J'' /-~
C ~ C ~ 2 ~ C 7 ~ ~ ! G ' C C ~ ~J D~ ~ ~ F s 1(~ Z~ t ~,r f7~Z~-'S<~e~ ~s 12q ~p~ c (--c C c~r/ E ~ r ,c ~ G ~ ' , _ ~ 3 <~ r~ _ h-4 ~
~ ; = o ~ u 5 7 ~ r f ~ t () f FCQ ~h~C ~' G ~C ~, ~, ~ p~ rc _ = ~ 3~ L~ PC
c~ 7 c~ ~ 4 ~ -~
A~ ~ASj FCc~ ~ Is .
( 2 ~ ) 'Z ~ L~
r;~ = ~/c7~ pO A~
(R T~' ~, .
7 ~f~ ~ 1V c Z Z ~ h ~ F J~ F~C æ 7 ~_ ~ O z ~ t f~ 6 -¦ ~J _~1J G '2 ~ 1. c- ~ p,' ~ 1 5 o . c c 6 ~ 5 J ~ 7 4 L~
7 ~(. C- As ~ C~J ~ ~1 " . ~o' CG ~ t,-r~ _I gC~ / s~ k ~ B~ ~ L~
S~f ~ CC~?~ c~ ~ t'~
c - ~ C = ~73 ~
L ~ t ~ o ~ /~ r S ~ ~7 ~ f ~ f~f l~ l c ~ Pc~ - s ~s ~ J E ~J ~ 5-r~ _ 12 ~C L~ P~ r i~ fC ~C~S- ~
I
- -~./f ~ ~ rI~ 5S ~ C,C~ R~
7 ~; 7 ~ E B C ~ ~ O ~ ~ ~ ~ C
r~ r ~ - - X ~ 1 5 C C ~ / r~ 6 7 Y / ~ ~r-(~S'l ~ s7 ~ X ~13 ~ k~ )~Z
~rY~ = I. IS4 ~9 /5 TO f(~O ~ 0~ PO~ ~ T(~F ~R T~ ~6~A~!~
P2f S5 ~ ~ ~ 7~ C Q E~ 0~ , 2 4 0 C C~
l2 C~C P~1 ~ PF R Fce ~, A CC~J ~ ~ t, ~ ~
~,1, lL ~ s 15 to~ ~HE ca~
4 A~ 2 -Z 2 ~, V
d (f o VC~ s~ ) t ~l~r~t =
.. 4~,~
~ O __ ~? G '~ f ~ ~ c ,l~ T,~ o ~ 2 1 4 ~ ~ 4 ~
- ~ Sy ~ T~ 7~ o ~ ~'. 6 ~
~ e~ fo = apT~ a.~( ~ey;~ O ~ze~
s;
c ~ 7 2 F~
"~
_ ~ 6672 /4~ (RTo~ I d~
I ~ V~an;sfer t~r~.4T ~J G ~
) e~cp .6~72 A~(RT~ t i*~ r~ t~ e~ (3 ~7Y/~ gq~2 4 a~ exp ~~ ~ S~ tl r P~ o ,, In - ~36 ~ Po7 f~ e,~(23~-/ lZ,~
_ 2. sq f = / s~ ~s~
Claims (7)
1. In a snowmobile having a body with a front end, a middle portion and a back end, top and bottom, and a flotation system integral thereto, said flotation system comprising:
a plurality of inflatable flotation means mounted at spaced locations on said snowmobile including two inflatable flotation means on opposed sides interior and underneath of said middle portion and one inflatable flotation means located interior and underneath of said front end; a compressed gas source; conduit means connecting said gas source with each of said inflatable flotation means; actuating means for releasing said compressed gas from said source to inflate said inflatable flotation means, said actuating means being integral with said source; each of said flotation means further comprising an inflatable envelope fluidly connected to said fluid passageway means; said envelope being collapsed prior to inflation, interiorly, underneath and within said body of said snowmobile enclosed by a sealed waterproof cover, continuous in nature.
a plurality of inflatable flotation means mounted at spaced locations on said snowmobile including two inflatable flotation means on opposed sides interior and underneath of said middle portion and one inflatable flotation means located interior and underneath of said front end; a compressed gas source; conduit means connecting said gas source with each of said inflatable flotation means; actuating means for releasing said compressed gas from said source to inflate said inflatable flotation means, said actuating means being integral with said source; each of said flotation means further comprising an inflatable envelope fluidly connected to said fluid passageway means; said envelope being collapsed prior to inflation, interiorly, underneath and within said body of said snowmobile enclosed by a sealed waterproof cover, continuous in nature.
2. The flotation system of claim 1 further comprising an integral puncture actuator and cannister system with conduit means connected to said cannister..
3. The flotation system of claim 2, wherein said actuator includes a manually actuable handle fluidly connected to a puncturing means .
4. The flotation system of claim 2, wherein said actuator further comprises an electrically operated explosive charge for automatic operation of said puncturing means.
5. The flotation system of claim 2 further comprising a flotation responsive switch mounted in a strategic location proximate the bottom immediately adjacent the exhaust pipe exit.
6. The flotation system of claim 1, wherein said inflatable envelope further comprises material substantially resistant to ice puncture and the like.
7. The flotation system of claim 1, wherein said system is used for saving lives in the event of said snowmobile falling through ice.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 shows the front end of the snowmobile in one embodiment, with the housing cover for the inflatable envelope open.
Figure 2 shows the snowmobile in one embodiment floating in the water after activation of the inflatable envelope.
Figure 3 shows the snowmobile in one embodiment floating in the water with two occupants thereon.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 shows the front end of the snowmobile in one embodiment, with the housing cover for the inflatable envelope open.
Figure 2 shows the snowmobile in one embodiment floating in the water after activation of the inflatable envelope.
Figure 3 shows the snowmobile in one embodiment floating in the water with two occupants thereon.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2142643 CA2142643A1 (en) | 1995-02-16 | 1995-02-16 | Snowmobile floatation system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2142643 CA2142643A1 (en) | 1995-02-16 | 1995-02-16 | Snowmobile floatation system |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2142643A1 true CA2142643A1 (en) | 1996-08-17 |
Family
ID=4155251
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2142643 Abandoned CA2142643A1 (en) | 1995-02-16 | 1995-02-16 | Snowmobile floatation system |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2142643A1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112810672A (en) * | 2020-12-30 | 2021-05-18 | 青岛鸿润发机械制造有限公司 | Anti-bumping multifunctional trolley for outdoor fishing |
-
1995
- 1995-02-16 CA CA 2142643 patent/CA2142643A1/en not_active Abandoned
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112810672A (en) * | 2020-12-30 | 2021-05-18 | 青岛鸿润发机械制造有限公司 | Anti-bumping multifunctional trolley for outdoor fishing |
| CN112810672B (en) * | 2020-12-30 | 2022-10-04 | 青岛鸿润发机械制造有限公司 | Anti-bumping multifunctional trolley for outdoor fishing |
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