CA1061417A - Cockpit canopy shattering system for escape of airmen - Google Patents
Cockpit canopy shattering system for escape of airmenInfo
- Publication number
- CA1061417A CA1061417A CA248,807A CA248807A CA1061417A CA 1061417 A CA1061417 A CA 1061417A CA 248807 A CA248807 A CA 248807A CA 1061417 A CA1061417 A CA 1061417A
- Authority
- CA
- Canada
- Prior art keywords
- canopy
- conductor
- sub
- capacitor
- electrical
- 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.)
- Expired
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B64—AIRCRAFT; AVIATION; COSMONAUTICS
- B64C—AEROPLANES; HELICOPTERS
- B64C1/00—Fuselages; Constructional features common to fuselages, wings, stabilising surfaces or the like
- B64C1/32—Severable or jettisonable parts of fuselage facilitating emergency escape
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Aviation & Aerospace Engineering (AREA)
- Fuses (AREA)
- Drilling And Exploitation, And Mining Machines And Methods (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
Apparatus for shattering an aircraft cockpit canopy in the path of an ejector seat, wherein the canopy has in intimate contact therewith, preferably embedded therein, a pattern of fusible conductors having at least one region of increased fusibility in each conductor. The conductors are connected via a switch system to a high energy electrical source, the switch system being linked with initiation of an ejection sequence. When ejection is initiated the conductors are fused and the canopy shattered at least in the path of the ejector seat.
Apparatus for shattering an aircraft cockpit canopy in the path of an ejector seat, wherein the canopy has in intimate contact therewith, preferably embedded therein, a pattern of fusible conductors having at least one region of increased fusibility in each conductor. The conductors are connected via a switch system to a high energy electrical source, the switch system being linked with initiation of an ejection sequence. When ejection is initiated the conductors are fused and the canopy shattered at least in the path of the ejector seat.
Description
106141~
The present invention relates to means enabling the escape of personnel from vehioles and craft, particularly aircraft, and especially through canopies and windscreens.
The problem of escape from modern high speed aircraft is generally solved by the use of an ejection seat which projects the airman out of the aircraft at high speed, thus avoiding impact with other parts of the fuselage or flying debris. In many cases there is no time for the canopy above the head of the airman to be opened in order to facilitate such escape and although, in some cases~ the canopy may be opened or removed bodily by mechanisms similar to that used for the ejection seat, even this may not be sufficiently rapid.
Appreciable time can be saved if, instead of removing the canopy as a whole, an opening is cut in it through which the airman can pass. This in itself presents a further problem, particularly since the tendency is for canopies to be strengthened so as to add to the overall safety of flight and to over-come hazards such as bird strike and so forth~ Such attempts as have been made so far in this direction have involved the use of explosive cord but this has been bulky and has consequently restricted visibility,has entailed in operation spattering of the person with undesirable substances, and is difficult of testing, over a long term~ that a particular system is still viable.
According to the present irvention a panel breaking system comprises a fusible electrical conductor arranged in intimate contact with the material of the panel in a geometric pattern related to the area of the required opening and connected to a source of electric power capable of producing a high energy pulse sufficient to produce fuzing of the conductor.
It will be apprPciated that the panel in this specification is frangible by 106~4~7 the means described and will normally therefore be made of a plastics materic~
of low electrical conductivity. The term "panel" includes cockpit c~n~pies c~nd windscreens inter alia. The invention is particularly suitable for use with polymethyl methacrylate and polycarbonate canopies.
The effect of such a pulse of current in an emergency, eg under the control of the same mechanism as used to operate the ejection seat, is to produce rupture of the conductor with consequent dissipation of energy and productior of an explosive shock sufficient to crack the material of the panel to form the required opening. In addition to the explosive shock, a degree of thermal shock is simultaneously experienced and the crack is propagated by mechanical shock/flexure waves through the material This can be carried out under much more closely controlled conditions than by the use of explosive cord and, moreover, an improvement in visibility results owing to the small cross-section of conductor required and the fact that the conductor can be placed at points on or in a canopy or windscreen where it does not obstruct the view.
The conductor is preferably embedded within the thickness of the panel during manufacture since this enables the most efficient tran~mission of the released energy into the material of the panel. This may be achieved either by placing the conductor between the layers of the laminated structure or by moulding the conductor directly into the panel. The conductor may also be embedded subsequent to manufacture by locating it in a groove or channel in the sur-face of the panel and subsequently filling this groove or channel.
~he fus;ble conductor may be in the form of a wire or tape and the effect may be enhanced by the inclusion of localised stress raisers~ that is to say regions which rupture before the remainder of the conductor under high power conditions, eg sharp bends in the conductor or short lengths of reduced cros6-section or a combination of both or the use of discrete 1~6~41~
conductor elements in contact at the stress raiser points. Small constric-tions along the length of the conductor have the effect of producing highly localised dissipation of energy at the location of such constrictions.
Cracks can be propagated over greater distances in the panel material~ parti-cularly when using a high energy pulse for shattering the material of the panel, by using a V ff haped bend in the conductor. This is because the plasma energy in the arc formed upon disruption of the conductor is directed along the median line of the angle of the bend in the conductor. The effect can be further enhanced by placing a constriction at the apex of the V.
Since the use of stress raisers, particularly those of V form can be used to direct cracks, it follows that a system of fusable elements~ each having one or more stress raisers can be disposed to create a desired mode of shattering. In a typical aircraft canopy context there is indeed a desired mode of cracking, this is that above the head and shoulders of the ejecting escaper the broken pieces and hence their momentum should be small enough not significantly to damage the person or vital equipment, while to the sides larger pieces can be tolerated. A system of fusable elements in accordance with the invention can readily be arranged to effect this with-out being visibly obstructive.
While the panel breaking means may merely so cra~e the canopy that the person may be safely ejected through it, it is usually preferable for it to be arranged completely to shatter the panel in the mode described in the previous paragraph. This is best accomplished by a combination of strategic siting of elements as described above with a source of adequate energy.
Two types of escape often need to be catered for in a canopy breaking system.
One is the ejection described above; the other is emergency egress which 1~61417 occurs when an aircraft has crash landed and the normal canopy opening meanc is inoperable or too slow of operation. This latter mode can be catered fo by canopy removal means, that is by means in accordance with the invention which separate at least most of the canopy from its frame, without necessa-rily shattering it.
A canopy breaking system may thus comprise both canopy shattering means and canopy removal means in accordance with the invention. These two sub-systems may be ganged for either purpose, ie upon ejection or upon emergency egress, both will operate, Operation of the canopy shattering means will normally be one event in a sequence initiated when the escaper selects to eject, thcugh there may be an additional fail safe microswitch operated by the passage of an ejector seat. The circuit for a canopy removal system may include two manual switches in parallel, one for operation by the escaper and the other~
perhaps beneath a removable or frangible ezterior panel, for operation from outside.
Of course either sub-system may be connected to act as an emergency or fail safe back-up for the other. Alternatively it may be preferred to use an explosive cord system for the canopy removal means, arranged to be opera-ted by manual switches internally and externally and by~afail safe switoh associated with the canopy shattering system.
The energy required is predetermined in accordance with the type of opera-tion required and also the thickness and material of the panel. The other variables which affect the required energy are the dimensions of the 10614~7 conductor (length and cross-seotional area) and also any variations in the geometry of the pattern. As a typical experimental example, a 6 inch square sample of either stretched aorylic or oast aorylic canopy material of thick-ness between 10 and 20 mm was shàttered by the use of a conductor consist-ing of 28 swg tin wire of ~- inches length in the form of an equilateral triangle embedded in the centre of the material using a stored energy of 500 Joules delivered in a time below 1 millisecond. Using nichrome wire in the same configuration and under the same conditions requires 1 kJ but delivered at half the rate to produce the same shattering effect.
These differences are the result of differences in the physical constants of the conductor materials, which may include metals and alloys and even carbon fibres. The particular physical constant of import in this case is the Joule integral ( J i dt) for melting. This is illustrated in the accompan~ing Figure 1 for a variety of materials as a function of the cross-sectional area of the conductor used to initiate the disoharge. The data represented in this graph are important in deciding the appropriate dimen-sion of the cross section of the element at the point where it is desired to disintegrate it. It can be readily seen from the graph that a reduction in cross section requires a much lower value of Joule integral, because the Joule integral is seen to be proportional to the square of the cross-sectional area, as is well known when applied in the field of electric fuses. It is for this reason that the small constrictions referred to above have the effect of producing highly localised dissipation of energy.
A variety of types of electrical power source are available capable of delivering the necessary amount of energy in the necessary short time interval. For example, sources using capaoitively stored energy or induc-tively stored energy are suitable as are also short time rated generators and thermal batteries. A very economical form of power souroe con~ists of capacitively stored energy matched to an inductance which i9 excited by the flow of ener~y from the capacitor during the melting time of the element chosen~ this form of course being particularly useful in creating the plasma projection in a Y formed element. Such melting time is determined by the data from the graph forming the drawing and a function of the capaci-tance~ inductance and resistance employed. Electrolytic or ceramic capacito:s-may be used, thus minimising the weight and bulk of the circuitry and reducing the required supply voltage.
The capacitors are preferably connected in series across supply~ as this will minimise the effect of a faulty capacitor. The fusable elements~
switches and inductances if used are then connected in sub-circuits across the capacitors, the switches being ganged for simultaneous operation. In a system having canopy shattering and canopy removal subffystems, each capacitor is advantageously shared between the sub-circuits of the two sub-systems. The supply may be derived from external points by which the capacitors may be charged prior to flight~ and possibly discharged after flight. In this case a trickle charger may be employed to maintain the charge during flight. Alternatively the supply may be derived indigenously, preferably in a system ~hereby the capacitors remain uncharged until required.
This may be realised using a set of supply switches in parallel, one for each sub-~ystem and contingency, connecting the capacitors to a source of the necessary high voltage supply when operated by the appropriate contin-gency. A delay system connected between each of the supply switches and the appropriate sub-system switches can be arranged to close these switches a few milliseconds after the operation of the supply switches, when the capacitors will have been adequately charged.
Successful shattering has been achieved with capacitors between 4 p~ and 10614~7 60 ~ at voltages up to ~.5 kV in combination with inductan¢e up to 110 and also with capacitors of an electrolytic type up to 30~000 ~UF capacity at voltages up to 450 V in conjunction with inductances up to 34 ~ ~ but the invention is by no means limited to this particular range of values.
A canopy breaking system will now be described by way of example with reference to the accompanying Figures 2 and 3, where:-Figure 2 is a view in perspective of an aircraft cockpit canopy fitted with fusable elements~ and Figure 3 is a circuit diagram.
As shown in Figure 2 an aircraft cockpit canopy comprises a transparent panel 11 in a frame 12. Embedded in the panel are five fusable elements 13 in a canopy shattering sub-system and eight fusable elements 14 in a canopy removal sub-system.
The elements 13 are strategically sited around the area of the canopy through which an aircrewman will go upon ejection, in positions where their effect upon visibility is minimised. The elements comprise tin tape 1 mm x 0.0~ mm x 300 mm long formed with a plurality of V bends pointing around and across the said area in such a manner that upon operation enough cracks will be generated in the area to break it into pieces which wqll have insufficient momentum significantly to damage the person or vital equipment. Leads 15 which connect the elements 13 into the sub-system circuit hzve ~ull-apart connectors 16 in the region of the frame 12.
The elements 14 are sited around the edge of the panel 11. Each comprises tin tape 1 mm x o.o8 mm x 100 mm formed with two V bends each pointing in an opposite direction along the perimeter of the panel. The circuit shown in Figure 3 comprises five electrolytic 30,00 ~ capacitors 20 connected in series between an external point 21 and earth Each capacitor 20 consti-tutes a power source for fusing elements within the canopy removal and canopy shattering sub-systems. Thus~ connected across each capaoitor 2 is a switch 22 a 30 ~H inductance 23 and, via conneotors 16 and leads 15 an element 13, in the shattering sub-system, and switches 2 4 and 25 in parallel, a 30 pH inductanoe 26 and at least one element 14 in the canopy removal sub-system. The switches 22 are ganged for simultaneous operation automatically as part of an ejection sequence. The switches-24 are ganged for simultaneous operation manually by the aircrewman and the switches 25 are ganged for oper2tion externally of the cockpit.
Within the canopy removal sub-system the three forward elements 14A are connected in series in one sub ff ystem circuit, the centre side and centre rear elements 14B~ C, E, are each connected in separate sub ff ystem circuits, and the two rear corner elements 14D are connected in series in another sub-system circuit, the five sub-system circuits thus made each being serviced by one of the capacitors 20.
A trickle charger 27 supplied from an aircraft busbar 28 is arranged to main-tain the charge on the capacitor 20.
The system is prepared for use before an aircraft sortie by charging the capacitors 20 using a 2.5 kV supply between the points 21 and earth.
During the sortie the charge is maintained using the trickle charger 27.
In the event of an aircrewman initiating ejection, the switches 22 will be closed automatically within the ejection sequence~ discharging the capacitors 20 through the inductances 23 and blowing the fuzes 13. Due to the current surge self-excited by the inductances 23 an arc will be set up across the disrupting fuse portions at the apex of the V arrangement or arrangements, and plasma will be directed along the median line of the V9 to augment the shock caused by the fuse itself. The crack system resulting from the careful location and arrangement of the elements 13 will ensure that at least the portion of the canopy in the path of the ejecting crewman and his seat will be broken into small pieces. The preæsure differential between the cockpit interior and atmosphere, augmented if necessary by location of the elements near to the inner and outer canopy surface~ will ensure that the pieces are projected outwards.
If the aircraft crash Iands the crewman will usually operate the rapid canopy removal sub-system rather than the normal opening means, and he will do so by closing the ganged switches 24. The capacitors 20 will then dis-charge through the inductances 26 and the elements 14, breaking the canopy away from the same in a mode of operation similar to that of the shattering sub-system. If the crewman is unconscious the switch 25 may be operated by an external rescuer, with the same effect. The panel is then pushed, pulled or lifted away from its frame, pulling apart the connectors 16 in the shattering sub-system.
In an alternative circuit~ the supply 21 is connected via a parallel switch system to a 2.5 kV sourc~e within`the aircraft. The parallel switch system comprises an automatic switch in the ejection sequence and associated with the shattering sub-system and two manual switches associated with the removal sub-system. Each of these switches is connected via a delay system with the appropriate switch, 23, 24, which latter switches are not, in this instance, operable other than by the delay system. The switch 25 and the trickle charge circuit 27 are not required.
In operation of this alternative circuit the capacitors 20 are not charged prior to flight and in fact remain uncharged until required. M aking of any of the switches in the said parallel switch ~ystem allows the ~upply to charge the capacitors and initiates operation of the delay ~ystem. After an appropriate number of milliseconds, when the capacitor 20 will be ade-quately charged~ the delay system will close the appropriate switch 23~ 24 and operate the associated sub-system.
~hat ha6 been described above i6 of course by way of exa ple. Clearly other ways of carrying out the inrention will occur to those skilled in the art~
and such other ways ay indeed be more suitable in certain circumstances. F~r exa~ple a continuous electrical conductor aay be used, arranged to break the panel along the path therof, a system more likely to be used in a c~nopy removal than a canopy shattering ~ystem. ~owe~er such a syste~ i8 less econo~ical or fail--safe than those described.
The systeos described can readily be teated for continuity, which can give a easure o~ certainty of viability unavailable in explosive cord systeas.
~oreover the use of a plurality of elements as particularly described aean that the system need not be seriously i-pared by the failure of one.
;
The present invention relates to means enabling the escape of personnel from vehioles and craft, particularly aircraft, and especially through canopies and windscreens.
The problem of escape from modern high speed aircraft is generally solved by the use of an ejection seat which projects the airman out of the aircraft at high speed, thus avoiding impact with other parts of the fuselage or flying debris. In many cases there is no time for the canopy above the head of the airman to be opened in order to facilitate such escape and although, in some cases~ the canopy may be opened or removed bodily by mechanisms similar to that used for the ejection seat, even this may not be sufficiently rapid.
Appreciable time can be saved if, instead of removing the canopy as a whole, an opening is cut in it through which the airman can pass. This in itself presents a further problem, particularly since the tendency is for canopies to be strengthened so as to add to the overall safety of flight and to over-come hazards such as bird strike and so forth~ Such attempts as have been made so far in this direction have involved the use of explosive cord but this has been bulky and has consequently restricted visibility,has entailed in operation spattering of the person with undesirable substances, and is difficult of testing, over a long term~ that a particular system is still viable.
According to the present irvention a panel breaking system comprises a fusible electrical conductor arranged in intimate contact with the material of the panel in a geometric pattern related to the area of the required opening and connected to a source of electric power capable of producing a high energy pulse sufficient to produce fuzing of the conductor.
It will be apprPciated that the panel in this specification is frangible by 106~4~7 the means described and will normally therefore be made of a plastics materic~
of low electrical conductivity. The term "panel" includes cockpit c~n~pies c~nd windscreens inter alia. The invention is particularly suitable for use with polymethyl methacrylate and polycarbonate canopies.
The effect of such a pulse of current in an emergency, eg under the control of the same mechanism as used to operate the ejection seat, is to produce rupture of the conductor with consequent dissipation of energy and productior of an explosive shock sufficient to crack the material of the panel to form the required opening. In addition to the explosive shock, a degree of thermal shock is simultaneously experienced and the crack is propagated by mechanical shock/flexure waves through the material This can be carried out under much more closely controlled conditions than by the use of explosive cord and, moreover, an improvement in visibility results owing to the small cross-section of conductor required and the fact that the conductor can be placed at points on or in a canopy or windscreen where it does not obstruct the view.
The conductor is preferably embedded within the thickness of the panel during manufacture since this enables the most efficient tran~mission of the released energy into the material of the panel. This may be achieved either by placing the conductor between the layers of the laminated structure or by moulding the conductor directly into the panel. The conductor may also be embedded subsequent to manufacture by locating it in a groove or channel in the sur-face of the panel and subsequently filling this groove or channel.
~he fus;ble conductor may be in the form of a wire or tape and the effect may be enhanced by the inclusion of localised stress raisers~ that is to say regions which rupture before the remainder of the conductor under high power conditions, eg sharp bends in the conductor or short lengths of reduced cros6-section or a combination of both or the use of discrete 1~6~41~
conductor elements in contact at the stress raiser points. Small constric-tions along the length of the conductor have the effect of producing highly localised dissipation of energy at the location of such constrictions.
Cracks can be propagated over greater distances in the panel material~ parti-cularly when using a high energy pulse for shattering the material of the panel, by using a V ff haped bend in the conductor. This is because the plasma energy in the arc formed upon disruption of the conductor is directed along the median line of the angle of the bend in the conductor. The effect can be further enhanced by placing a constriction at the apex of the V.
Since the use of stress raisers, particularly those of V form can be used to direct cracks, it follows that a system of fusable elements~ each having one or more stress raisers can be disposed to create a desired mode of shattering. In a typical aircraft canopy context there is indeed a desired mode of cracking, this is that above the head and shoulders of the ejecting escaper the broken pieces and hence their momentum should be small enough not significantly to damage the person or vital equipment, while to the sides larger pieces can be tolerated. A system of fusable elements in accordance with the invention can readily be arranged to effect this with-out being visibly obstructive.
While the panel breaking means may merely so cra~e the canopy that the person may be safely ejected through it, it is usually preferable for it to be arranged completely to shatter the panel in the mode described in the previous paragraph. This is best accomplished by a combination of strategic siting of elements as described above with a source of adequate energy.
Two types of escape often need to be catered for in a canopy breaking system.
One is the ejection described above; the other is emergency egress which 1~61417 occurs when an aircraft has crash landed and the normal canopy opening meanc is inoperable or too slow of operation. This latter mode can be catered fo by canopy removal means, that is by means in accordance with the invention which separate at least most of the canopy from its frame, without necessa-rily shattering it.
A canopy breaking system may thus comprise both canopy shattering means and canopy removal means in accordance with the invention. These two sub-systems may be ganged for either purpose, ie upon ejection or upon emergency egress, both will operate, Operation of the canopy shattering means will normally be one event in a sequence initiated when the escaper selects to eject, thcugh there may be an additional fail safe microswitch operated by the passage of an ejector seat. The circuit for a canopy removal system may include two manual switches in parallel, one for operation by the escaper and the other~
perhaps beneath a removable or frangible ezterior panel, for operation from outside.
Of course either sub-system may be connected to act as an emergency or fail safe back-up for the other. Alternatively it may be preferred to use an explosive cord system for the canopy removal means, arranged to be opera-ted by manual switches internally and externally and by~afail safe switoh associated with the canopy shattering system.
The energy required is predetermined in accordance with the type of opera-tion required and also the thickness and material of the panel. The other variables which affect the required energy are the dimensions of the 10614~7 conductor (length and cross-seotional area) and also any variations in the geometry of the pattern. As a typical experimental example, a 6 inch square sample of either stretched aorylic or oast aorylic canopy material of thick-ness between 10 and 20 mm was shàttered by the use of a conductor consist-ing of 28 swg tin wire of ~- inches length in the form of an equilateral triangle embedded in the centre of the material using a stored energy of 500 Joules delivered in a time below 1 millisecond. Using nichrome wire in the same configuration and under the same conditions requires 1 kJ but delivered at half the rate to produce the same shattering effect.
These differences are the result of differences in the physical constants of the conductor materials, which may include metals and alloys and even carbon fibres. The particular physical constant of import in this case is the Joule integral ( J i dt) for melting. This is illustrated in the accompan~ing Figure 1 for a variety of materials as a function of the cross-sectional area of the conductor used to initiate the disoharge. The data represented in this graph are important in deciding the appropriate dimen-sion of the cross section of the element at the point where it is desired to disintegrate it. It can be readily seen from the graph that a reduction in cross section requires a much lower value of Joule integral, because the Joule integral is seen to be proportional to the square of the cross-sectional area, as is well known when applied in the field of electric fuses. It is for this reason that the small constrictions referred to above have the effect of producing highly localised dissipation of energy.
A variety of types of electrical power source are available capable of delivering the necessary amount of energy in the necessary short time interval. For example, sources using capaoitively stored energy or induc-tively stored energy are suitable as are also short time rated generators and thermal batteries. A very economical form of power souroe con~ists of capacitively stored energy matched to an inductance which i9 excited by the flow of ener~y from the capacitor during the melting time of the element chosen~ this form of course being particularly useful in creating the plasma projection in a Y formed element. Such melting time is determined by the data from the graph forming the drawing and a function of the capaci-tance~ inductance and resistance employed. Electrolytic or ceramic capacito:s-may be used, thus minimising the weight and bulk of the circuitry and reducing the required supply voltage.
The capacitors are preferably connected in series across supply~ as this will minimise the effect of a faulty capacitor. The fusable elements~
switches and inductances if used are then connected in sub-circuits across the capacitors, the switches being ganged for simultaneous operation. In a system having canopy shattering and canopy removal subffystems, each capacitor is advantageously shared between the sub-circuits of the two sub-systems. The supply may be derived from external points by which the capacitors may be charged prior to flight~ and possibly discharged after flight. In this case a trickle charger may be employed to maintain the charge during flight. Alternatively the supply may be derived indigenously, preferably in a system ~hereby the capacitors remain uncharged until required.
This may be realised using a set of supply switches in parallel, one for each sub-~ystem and contingency, connecting the capacitors to a source of the necessary high voltage supply when operated by the appropriate contin-gency. A delay system connected between each of the supply switches and the appropriate sub-system switches can be arranged to close these switches a few milliseconds after the operation of the supply switches, when the capacitors will have been adequately charged.
Successful shattering has been achieved with capacitors between 4 p~ and 10614~7 60 ~ at voltages up to ~.5 kV in combination with inductan¢e up to 110 and also with capacitors of an electrolytic type up to 30~000 ~UF capacity at voltages up to 450 V in conjunction with inductances up to 34 ~ ~ but the invention is by no means limited to this particular range of values.
A canopy breaking system will now be described by way of example with reference to the accompanying Figures 2 and 3, where:-Figure 2 is a view in perspective of an aircraft cockpit canopy fitted with fusable elements~ and Figure 3 is a circuit diagram.
As shown in Figure 2 an aircraft cockpit canopy comprises a transparent panel 11 in a frame 12. Embedded in the panel are five fusable elements 13 in a canopy shattering sub-system and eight fusable elements 14 in a canopy removal sub-system.
The elements 13 are strategically sited around the area of the canopy through which an aircrewman will go upon ejection, in positions where their effect upon visibility is minimised. The elements comprise tin tape 1 mm x 0.0~ mm x 300 mm long formed with a plurality of V bends pointing around and across the said area in such a manner that upon operation enough cracks will be generated in the area to break it into pieces which wqll have insufficient momentum significantly to damage the person or vital equipment. Leads 15 which connect the elements 13 into the sub-system circuit hzve ~ull-apart connectors 16 in the region of the frame 12.
The elements 14 are sited around the edge of the panel 11. Each comprises tin tape 1 mm x o.o8 mm x 100 mm formed with two V bends each pointing in an opposite direction along the perimeter of the panel. The circuit shown in Figure 3 comprises five electrolytic 30,00 ~ capacitors 20 connected in series between an external point 21 and earth Each capacitor 20 consti-tutes a power source for fusing elements within the canopy removal and canopy shattering sub-systems. Thus~ connected across each capaoitor 2 is a switch 22 a 30 ~H inductance 23 and, via conneotors 16 and leads 15 an element 13, in the shattering sub-system, and switches 2 4 and 25 in parallel, a 30 pH inductanoe 26 and at least one element 14 in the canopy removal sub-system. The switches 22 are ganged for simultaneous operation automatically as part of an ejection sequence. The switches-24 are ganged for simultaneous operation manually by the aircrewman and the switches 25 are ganged for oper2tion externally of the cockpit.
Within the canopy removal sub-system the three forward elements 14A are connected in series in one sub ff ystem circuit, the centre side and centre rear elements 14B~ C, E, are each connected in separate sub ff ystem circuits, and the two rear corner elements 14D are connected in series in another sub-system circuit, the five sub-system circuits thus made each being serviced by one of the capacitors 20.
A trickle charger 27 supplied from an aircraft busbar 28 is arranged to main-tain the charge on the capacitor 20.
The system is prepared for use before an aircraft sortie by charging the capacitors 20 using a 2.5 kV supply between the points 21 and earth.
During the sortie the charge is maintained using the trickle charger 27.
In the event of an aircrewman initiating ejection, the switches 22 will be closed automatically within the ejection sequence~ discharging the capacitors 20 through the inductances 23 and blowing the fuzes 13. Due to the current surge self-excited by the inductances 23 an arc will be set up across the disrupting fuse portions at the apex of the V arrangement or arrangements, and plasma will be directed along the median line of the V9 to augment the shock caused by the fuse itself. The crack system resulting from the careful location and arrangement of the elements 13 will ensure that at least the portion of the canopy in the path of the ejecting crewman and his seat will be broken into small pieces. The preæsure differential between the cockpit interior and atmosphere, augmented if necessary by location of the elements near to the inner and outer canopy surface~ will ensure that the pieces are projected outwards.
If the aircraft crash Iands the crewman will usually operate the rapid canopy removal sub-system rather than the normal opening means, and he will do so by closing the ganged switches 24. The capacitors 20 will then dis-charge through the inductances 26 and the elements 14, breaking the canopy away from the same in a mode of operation similar to that of the shattering sub-system. If the crewman is unconscious the switch 25 may be operated by an external rescuer, with the same effect. The panel is then pushed, pulled or lifted away from its frame, pulling apart the connectors 16 in the shattering sub-system.
In an alternative circuit~ the supply 21 is connected via a parallel switch system to a 2.5 kV sourc~e within`the aircraft. The parallel switch system comprises an automatic switch in the ejection sequence and associated with the shattering sub-system and two manual switches associated with the removal sub-system. Each of these switches is connected via a delay system with the appropriate switch, 23, 24, which latter switches are not, in this instance, operable other than by the delay system. The switch 25 and the trickle charge circuit 27 are not required.
In operation of this alternative circuit the capacitors 20 are not charged prior to flight and in fact remain uncharged until required. M aking of any of the switches in the said parallel switch ~ystem allows the ~upply to charge the capacitors and initiates operation of the delay ~ystem. After an appropriate number of milliseconds, when the capacitor 20 will be ade-quately charged~ the delay system will close the appropriate switch 23~ 24 and operate the associated sub-system.
~hat ha6 been described above i6 of course by way of exa ple. Clearly other ways of carrying out the inrention will occur to those skilled in the art~
and such other ways ay indeed be more suitable in certain circumstances. F~r exa~ple a continuous electrical conductor aay be used, arranged to break the panel along the path therof, a system more likely to be used in a c~nopy removal than a canopy shattering ~ystem. ~owe~er such a syste~ i8 less econo~ical or fail--safe than those described.
The systeos described can readily be teated for continuity, which can give a easure o~ certainty of viability unavailable in explosive cord systeas.
~oreover the use of a plurality of elements as particularly described aean that the system need not be seriously i-pared by the failure of one.
;
Claims (25)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A panel breaking system comprising at least one electrical conductor arranged in intimate contact with the material of the panel in a geometric pattern related to the area of the required opening and associated with a source of electric power capable of producing a high energy pulse of current sufficient to fuse the conductor.
2. A breaking system as claimed in claim 1 and wherein the said at least one electrical conductor is embedded within the panel.
3. A system as claimed in claim 1 and wherein the said at least one electrical conductor incorporates at least one stress raiser.
4. A system as claimed in claim 3 and wherein the said at least one stress raiser comprises a V-shaped arrangement of the conductor.
5. A system as claimed in claim 3 and wherein the said at least one stress raiser comprises a constriction in the conductor.
6. A system as claimed in claim 1 and arranged to shatter an area of an aircraft cockpit canopy.
7. A system as claimed in claim 6 and arranged to separate at least most of the cockpit canopy from its frame.
8. A system as claimed in claim 6 and comprising 2 sub-systems, one for shattering an area of the cockpit canopy in the path of an ejecting crew-man and the other for separating at least most of the canopy from its frame.
9. A system as claimed in claim 1 and wherein the said at least one electrical conductor is made of tin.
10. A system as claimed in claim 1 and wherein the said at least one electrical conductor is in tape form.
11. A system as claimed in claim 1 and wherein the source of electrical power comprises at least one capacitor.
12. A system as claimed in claim 11 and wherein the said at least one capacitor is an electrolytic capacitor.
13. A system as claimed in claim 11 and wherein the said at least one capacitor is a ceramic capacitor.
14. A system as claimed in claim 11 and wherein the capacitor is matched to an inductance.
15. An aircraft cockpit canopy shattering system comprising a plurality of electrical conductors in the form of fusible elements each incorporating at least one stress raiser, and one source of electrical power for each conductor, the electrical conductors being embedded in the canopy material in a pattern such that upon fusing they will shatter into small pieces that area of the canopy through which a crewman must pass, and the sources of electrical power being arranged upon initiation to fuse the fusible elements.
16. A system as claimed in claim 15 and wherein the stress raisers com-prise V-shaped arrangements of the fusible elements.
17. A system as claimed in claim 15 and wherein the sources of electrical power comprise capacitors matched to inductances.
18. A system as claimed in claim 17 and wherein the said at least one capacitor is arranged to be charged prior to flight.
19. A system as claimed in claim 17 and having switch means operated within an ejection sequence to initiate discharge of the capacitors.
20. A system as claimed in claim 15 and comprising first switch means operable to supply power to charge the capacitors, a delay system initiated by the first switch means, and second switch means operable by the delay to initiate discharge of the capacitors.
21. An aircraft cockpit canopy breaking system comprising a shattering sub-system as claimed in claim 15 and a canopy removal sub-system incorporating a plurality of electrical conductors in the form of fusible elements, each having at least one stress raiser and each disposed within the canopy material so that upon operation a portion of the canopy can be cut away from the rest, at least one source of electrical power arranged for fusing the fusible elements, and at least one manually operable switch for connecting the said at least one source of power to the fusible elements.
22. A system as claimed in claim 21 and wherein the said at least one power system is common to both sub-systems.
23. A system as claimed in claim 21 and wherein the stress raisers com-prise V-shaped arrangements of the fusible elements.
24. A system as claimed in claim 21 and having a second manually operable switch in parallel with that claimed therein, the first said switch being located for operation by the crewman, and the second said switch being located for operation external to the aircraft.
25. A system as claimed in claim 21 and wherein the canopy removal sub-system is arranged to cut substantially the whole canopy from its frame.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB1276075A GB1550352A (en) | 1975-03-26 | 1975-03-26 | Cockpit canopy shattering apparatus |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1061417A true CA1061417A (en) | 1979-08-28 |
Family
ID=10010631
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA248,807A Expired CA1061417A (en) | 1975-03-26 | 1976-03-25 | Cockpit canopy shattering system for escape of airmen |
Country Status (4)
| Country | Link |
|---|---|
| CA (1) | CA1061417A (en) |
| DE (1) | DE2612574A1 (en) |
| FR (1) | FR2305341A1 (en) |
| GB (1) | GB1550352A (en) |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4405104A (en) * | 1977-12-14 | 1983-09-20 | The Secretary Of State For Defence In Her Britannic Majesty's Government Of The United Kingdom Of Great Britain And Northern Ireland | Panel breaking apparatus |
| FR2411757A1 (en) * | 1977-12-14 | 1979-07-13 | Bolton Colin | Vehicle-capsule boundary disruption system - uses criss=cross conducting strips in boundary or cockpit canopy, melted by electric current |
| US4301707A (en) * | 1979-10-29 | 1981-11-24 | Mcdonnell Douglas Corporation | Embedded explosive severance of non-metallic materials |
| US4279405A (en) * | 1979-11-26 | 1981-07-21 | Buryakov Valery M | Device for making emergency exits in a crushed transport means |
| DE2949778C2 (en) * | 1979-12-11 | 1984-11-08 | Gosudarstvennyj naučno-issledovatel'skij institut graždanskoj aviacii, Moskva | Device for rapid and simultaneous severing of the wall of a means of transport, in particular the fuselage wall of an aircraft |
| DE10114860B4 (en) * | 2001-03-26 | 2005-03-03 | Henry Tunger | Device for opening an emergency exit in motor vehicles |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3340807A (en) * | 1965-10-04 | 1967-09-12 | Itt | Exploding wire techniques |
| GB1383513A (en) * | 1971-06-10 | 1974-02-12 | Hawker Siddeley Aviation Ltd | Aircrew escape systems |
-
1975
- 1975-03-26 GB GB1276075A patent/GB1550352A/en not_active Expired
-
1976
- 1976-03-24 DE DE19762612574 patent/DE2612574A1/en active Granted
- 1976-03-25 FR FR7608752A patent/FR2305341A1/en active Granted
- 1976-03-25 CA CA248,807A patent/CA1061417A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| DE2612574C2 (en) | 1987-10-15 |
| GB1550352A (en) | 1979-08-15 |
| FR2305341B1 (en) | 1981-03-06 |
| FR2305341A1 (en) | 1976-10-22 |
| DE2612574A1 (en) | 1976-10-07 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US4275858A (en) | Panel breaking systems | |
| US2395435A (en) | Emergency control mechanism for aircraft | |
| CA1061417A (en) | Cockpit canopy shattering system for escape of airmen | |
| DE112016004764B4 (en) | Pyrotechnic separation device | |
| US20040041682A1 (en) | Battery circuit disconnect device | |
| DE102018125059A1 (en) | High voltage electric line cutter device | |
| DE102016222339A1 (en) | PYROTECHNICAL SWITCH AND INTERMEDIATE DISCHARGE SYSTEM | |
| US4405104A (en) | Panel breaking apparatus | |
| EP2778068B1 (en) | Blade safety mechanism for open rotor engine system | |
| US3453415A (en) | Aircraft deicing system | |
| US3067973A (en) | Ejectable flight capsule | |
| EP3622548B1 (en) | Pyrotechnic circuit breaker and supply system having a pyrotechnic circuit breaker | |
| US3670998A (en) | Severance of polycarbonate material canopy transparency | |
| DE102013203482A1 (en) | Transport trolley for tablet computer and control method | |
| CN101487681B (en) | Cutting method for emergency opening lock catch of cabin door for passenger plane test flight service | |
| CN109131947B (en) | Ultra-high-speed impact protection device and method | |
| US4570880A (en) | Arrangement of devices to sever and remove canopy wall sections from aircraft cockpits | |
| KR101567823B1 (en) | A slide ejection seat for flying cars and the driving method thereof | |
| US2189147A (en) | Fire preventing and extinguishing apparatus | |
| CA1102295A (en) | Panel breaking apparatus | |
| US3260810A (en) | Electric switch with frangible and expendable electrodes | |
| US20230182907A1 (en) | Multi-seat escape system and ejection seat sequencer | |
| Lewis | Spinal injuries caused by the acceleration of ejection | |
| US1970812A (en) | Aircraft | |
| CN109502031B (en) | Electronic emergency separating device |