US3408026A

US3408026A - Variable time delay reefing line cutter

Info

Publication number: US3408026A
Application number: US677591A
Authority: US
Inventors: Marshall S Kriesel
Original assignee: AEROSPACE SYSTEMS CO
Current assignee: AEROSPACE SYSTEMS CO
Priority date: 1967-10-24
Filing date: 1967-10-24
Publication date: 1968-10-29
Anticipated expiration: 1985-10-29

Description

Oct. 29, 1968 M. s. KRIESEL.

VARIABLE TIME DELAY REEFING LINE CUTTER -Sheet 1 l-VVENTOR. MA RSHALL S. KKIESEL 2 Sheets Filed Oct. 24, 1967 lrromvty:

1968 M. s. KRIESEL.

VARIABLE TIME DELAY REEFING LINE CUTTER 2 Sheets-Sheet 2 Filed Oct. 24, 1967 INVENTOR. MA RSHALL I. KRMSEL drum/Er:

United States atent 3,408,026 VARIABLE TIME DELAY REEFING LINE CUTTER Marshall S. Kriesel, St. Paul, Minn., assignor to Aerospace Systems Company, Minneapoiis, Millm, a corporation of California Filed Oct. 24, 1967, Ser. No. 677,591 9 Claims. (Cl. 244-152) ABSTRACT OF THE DISCLOSURE A reefing line cutter for use with cargo carrying parachutes having actuation means which will delay the time of actuation of the reefing line cutter, and consequently delays the time when the reefing line is cut after actuation so that the reefing line will not be cut until the load is proximate the ground after being dropped by aircraft. The cutter has actuating means including a replaceable time delay element. The time delay element can be changed. The element used is fired automatically upon ejection of the cargo carrying parachute and will actuate the reefing line cutter after a preselected length of time. The replaceable element is mounted onto the end of a long, flexible leader made of a pyrotechnic line covered with elastomeric material which is of length to protrude outside the folded cargo parachute so that the time delay element can be changed in flight if conditions change.

BACKGROUND OF THE INVENTION Field of the invention The present invention relates to variable time delay actuation means used specifically with reefing line cutters for cutting a reefing line on cargo carrying parachutes.

The prior art Reefing line cutters presently in use are generally actuated by the sending of an electrical impulse through conductors to the cutter located on the parachute so that the reefing line cutter will be energized after the cargo chute has cleared the aircraft. However, with the electrical actuation, the problems arising from broken conductors, shorting of the system, and the need for actuation of the cutter before it leaves, at the time it leaves or shortly after it has left the aircraft, limit the applicability of this type of system. When the cargo is dropped from a substantial altitude and the reefing line is cut as soon as the parachute leaves the aircraft, the full parachute is subjected to wind in its fully unfurled condition for a greater length of time. This makes accuracy of the drop harder to obtain. Further, the use of electric initiation for reefing line cutters makes the unit somewhat sensitive to static electricity, radio frequency stray currents, and also there are elaborate ground check out procedures for the circuits before the chutes were loaded. The check out procedure required electrical checking equipment as well.

SUMMARY OF THE INVENTION The present invention consists of an ordinance actuated reefing line cutter with integral impulse transmission line attached and an insertable time delay ignition element. The ignition element can be easily replaced so that the amount of time delay can be changed as desired. The ignition element is actuated with a standard military firing pin breach assembly acting on a percussion cap that ignites a pyrotechnic compound that in turn will burn at a set rate and will then actuate a fuse-like ignition assembly to ignite a pressure cartridge used as the prime mover for the reefing line cutter, after the preselected time.

The transfer from the time delay cartridge to the pressure cartridge is accomplished by the use of a pyrotechnic material encapsuled in an elastomeric material and which Patented Oct. 29, 1968 'ice can be elongated so that the time delay cartridge extends out of the folded parachute when the parachute is in place in the aircraft. This means that the time delay cartridges can be changed by the crew to meet changing conditions.

BRIEF DESCRIPTION OF THE DRAWINGS FIGURE 1 is a fragmentary perspective view of a cargo having a cargo parachute installed thereon, and showing a replaceable time delay element used with the reefing line cutter extending from the parachute;

FIGURE 2 is a perspective view of a reefing line cutter having the variable time delay capsule attached thereto in position as it would be prior to cutting the reefing line;

FIGURE 3 shows the reefing line cutter of the present invention as it would appear in a dropping parachute prior to the time of dereefing the chute; and

FIGURE 4 is an exploded vertical sectional view of the variable time delay reefing line cutter made according to the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT In FIGURE 1, there is shown a box of cargo 10 arranged with cargo carrying straps 11 which is used for dropping supplies to persons on the ground from an aircraft. The straps 11 are used for tying the cargo together, and load support straps 12 are also used and these would be attached to the suspension lines 13 of the chute when it is opened.

A parachute 14 which is packed as shown in FIGURE 1, is placed on top of the cargo 10. The parachute package has static lines 15 protruding therefrom which are used for unfurling the chute when the cargo is ejected from the aircraft. The static lines 15 are normally snapped onto a line or ring in the aircraft and when the cargo is ejected, the chute is dragged out by the static lines.

A variable time delay reefing line cutter assembly illustrated generally at 16 is installed within the folded chute as will be more fully shown later and is mechanically actuated with a variable firing and time delay element assembly 17. The element assembly is mounted onto the end of a flexible fuse-like line 18 that extends out of the chute package so that the quick change assembly of the variable time delay actuator is accessible to the crew of the aircraft prior to the time the cargo is dropped. The

time delay element assembly 17 has a trigger 21 with a ring 22 attached thereto. The ring 22 in turn is attached with a cord 23 to the static line hook up element 24 for the static lines 15. As the static lines are pulled out when the cargo is ejected,'the mechanical trigger 21 will be actuated to energize the time delay assembly and cause eventual dereefing of the parachute by cutting the reefing line. The static lines are hooked to a cable inside the aircraft so that when the load ejects the lines are pulled to open the parachute.

Referring specifically to FIGURE 3, the parachute canopy 25, as is customary, has canopy loops 26 at the peripheral edge thereof and each of the canopy loops has a suspension line 13 attached thereto. Suspension lines 13 then attach as at 28 to the support lines 12 for the cargo. While FIGURE 3 is shown in its horizontal direction, it should be noted that the load would be vertically below the canopy and the orientation of the figure was merely for convenience in illustrating it.

A reefing line 27 is passed through the canopy loops and holds the canopy 25 in a partially reefed condition as shown in solid lines in FIGURE 3 after the parachute has been released and the cargo is descending. The rate of descent is quite high, because the chute is reefed and in order to slow this rate of descent so the cargo is deposited gently, the reefing line 27 is cut so that the canopy opens to its fully opened position as shown in dotted lines in FIGURE 3. The variable time delay reefing line cutter assembly 16 of the presentinvent'ion permits the delay of the cutter actuation time as well as permitting the mechanical actuation of the reefing line cutter.

The cutter assembly itself illustrated generally at includes a body 31 having an Opening through which the reefingline cutter passes and an upright member 32 to which a latch 33 is pivotally attached. The latch 33 forms a'pocket 34 which will receive the canopy loop 26, and when the latch is closed as shown in FIGURE '2, the nut 35 is closed down onto the latch ends and holds the latch in position. The latch 33 includes a slot 36 which is of size to permit'the suspension line 13 to pass therethrough. The suspension line 13 is attached to the canopy loop 26 to which the reefing line cutter assembly is also attached; The reefing line cutter body made such as that shown, is shown in greater detail in Us. Patent No. 3,348,793. However, electrical actuation is shown for the reefing line cutter in that patent.

The cutter body, as shown perhaps best in FIGURE 4, houses a guillotine type cutter 37 which is actuable inside a chamber so that it will move from position as shown in FIGURE 4 to a cutting position with the cutting edge 37a against the stop 38. The reefing line 27 at that time will'have been severed inasmuch as it passes through a cross hole through the chamber 43 for the cutter 37. The body 31 houses an ordinance cartridge 39 which has a charge 42 of explosive compound therein. When the explosive compound 42 is ignited, it will form pressure inside the chamber 43 behind the cutter and force the cutter against the stop surface 38 to sever the reefing line 27. The ordinance cartridge 39 is threaded into the housing 31. The ordinance cartridge 39 has a rearwardly projecting stem 44 on which an elastomeric material forming elongated line 18 is molded. The nut 35 is mounted over the elastomeric material and threadably engages external threads on the stem 44 so that it can be threaded down against the latch 33 to hold the latch in place.

The line 18 is held in place with suitable grooves on the stem and is elongated as shown a sufiicient distance so that it will protrude outside a folded parachute package. In the interior of the line 18 there is a fuse-like pyrotechnic line 45 which will burn when ignited at a controlled rate and will eventually ignite and cause the charge 42 to burn. The pyrotechnic line is thus completely encased in the elastomeric material 46 forming line 18. 'In an outer end portion 47 of the line 18 is enlarged to encompass and mount a mounting member 48. Mounting member 48.is covered with the elastomeric material as well and forms an integral assembly. The mounting member 48 is cylindrical member having an interior chamber 51. The mounting member. 48 has a charge of pyrotechnic material 52 at the inner end thereof and the pyrotechnic line 45 is embedded in this charge. The charge 52 is open to the interior chamber 51. The line 45 is made and sold by McCormick Selph/ A Teledyne Company, Hollister, Calif.

A variable time delay quick change unit 17 includes a main body 53 which is of size to slide within chamber 51. The body 53 has a collar 54 rotatably mounted thereon at the outer end thereof. The collar 54 is spaced from the outer surface of the body itself so that there is a chamber into which the mounting member 48 will slide. The collar 54 locks onto small lock knobs 55 to hold the assembly 17 in place in the mounting member. This is a quick change lock which can either be partial twist as shown (it can also have pin grooves inside the collar like a bayonet lamp base socket), or a snap lock with small spring loaded lugs such as 55, or any other quick change arrangement. The protruding portion 56 of the body 53 is of larger size than the main portion of the body. This section protrudes out from the mounting member 48.

The interior of the main body 53 has a chamber in 4 which a time delay element 57 is mounted. The time delay element can consist of several windings of a linear pyrotechnic line such as that shown at 45 around the central core member 58. The rate of burning of this fuselike pyrotechnic line is known and therefore the length of line necessary for'a known time'delay can be found.

One end of the line forming the time delay element 57 is embedded in a percussion cap 61 at the inner end of the assembly and the outer end of the line is embedded in a transfer or output charge 62. The output charge is of a suitable ignition material which will ignite the pickup charge 52 after the time delay has been initiated. A spring loaded firing pin 63 is mounted into an interior chamber 64. The pin 63 has a center member that extends into a collar 65 at the outer end of the body 53 and is slidably mounted and guided therein. A spring 66 is mounted behind the firing pin head and abuts against an inner end of the chamber 64. The firing pin actuator 21 is also mounted into collar 65. The actuator 21 interlocks as shown at 68 with the outer end of the firing pin, and when both of them are in the collar, they cannot be separated. However, the actuator 21 can be pulled in direction as indicated by the arrow 71 so that interlock portion 68 clears the collar 65. At that time, the actuator portion will disengage the firing pin and release the pin. It should be noted that by the time the interlock section clears the collar, the spring 66 will be compressed a great amount and the firing pin will be fired at the percussion cap 61 in opposite direction from that indicated by arrow 71. This will fire the percussion cap, ignite the time delay element 57 and then the entire unit will be energized. The ring 22 is actually mounted in the actuator member 21. A cross hole 72 extends through the collar portion 65 and aligns with a hole in the actuator section 21 when the unit is in its ready position. The safety pin 73 can be inserted through the cross hole to prevent the actuator member from being pulled out in direction as indicated by arrow 71 and prevent accidental firing of the time delay cartridge.

The mounting member 58 for the time delay element 57, as shown, is a spool-like member having two end sections 74, .74 joined together by a center section 75. The time delay line which is a linear burning pyrotechnic line, can then be wound onto the spool so that it will fit within the interior chamber of the housing 53. The length of line determines the length of time delay, and this can be accurately made because the pyrotechnic line is designed to burn at a predetermined rate. Thus it is merely a matter of measuring out the amount of line necessary for a given time delay, winding it onto the spool mounting member 58, and then placing the assembly with the appropriate percussion cap at one end, and the transfer charge at the other end, and then mounting the unit inside the housing 53. Likewise, a standard military firing pin 63 can be used with merely the interlock for the actuator section 21 made so that the unit will be held in place. When the pin is pulled rearwardly in the interlock made, the actuator section 21 has a shoulder 76 that abuts against the end of the collar 65 to hold the pin from firing the charge until the actuator section is released.

The time delays can be made from one second up to five minutes if desired, at the present time. The line 45 inside the flexible line 18 also serves as a time delay because the burning rate of this line is known. The flexible line is of sutficient length so that it will extend out from the folded parachute so that the quick change element 17 can easily be inserted in the mounting member or removed as desired. All that is necessary is a visual check to make sure that the time delay element is in place, and then the ring 22 is fastened to the static line. When the static-line is pulled, the ring 22 will be pulled moving this actuator 21 in direction as indicated by arrow 71 until the interlock section 68 with the firing pin releases causing the firing pin to fire. That is the initiation of the time delay. This happens when the load is dropped,

and the parachute is opened partially as shown in FIG- URE 3. Then after the time delay, the reefing line 27 will be cut permitting the canopy 25 of the parachute to fully unfurl (as shown in dotted lines in FIGURE 3) and slow the descent of the cargo to the desired speed upon contact.

If the planned flight program is altered or a different cargo extraction altitude is chosen after the plane is in the air, the crew or loadmaster in the aircraft will remove the original time delay element and replace it with a different time delay element. The navigator can give the values necessary, and a complete a range of time delay elements can be easily stored on the aircraft itself. Of course, it is obvious that the time delay elements can be stamped with the amount of time delay or color coded if desired. After the elements have been replaced, it is merely a matter of retying the firing pin actuator 21 to the parachute static lines and the cargo can be deployed immediately.

The free movement of the flexible line 18 permits this ease of inspection and insertion of the time delay elements. Yet, at the same time, the cutter is positively positioned by looping it under the canopy loop 26 and the associated suspension lines 13. This keeps the reefing line cutter positively positioned so that it will cut whenever it is actuated.

Of course, the safety pin 73 will have to be removed before the load is extracted so that the firing pin will fire.

By permitting the cutting of the reefing line when the cargo is close to the ground, the trajectory of the load can be more closely calculated so that even though the load may be dropped from a high altitude, the effect of wind drift will be minimized. When the chute is dropping in a reefed condition, the wind has a lesser effect than when the chute is fully unfurled. Thus the amount of time that the chute is fully unfurled should be kept to a minimum.

Mechanical actuation gives high reliability performance and safety because there is no high explosive detonations. Functionally it is completely reliable because the components such as the pyrotechnic line 45 can be enclosed in an elastomeric material and completely sealed from the weather. The time delay elements also can be stored so that they are uneffected by the ambient conditions and will perform reliably each time.

What is claimed is:

1. In a cargo carrying parachute folded into a parachute package before use and having means including a line which, when severed, is operative to fully depoly the parachute as it drops, and a cutter to cut said line upon receiving a given signal, the improvement comprising actuation means for said cutter including an elongated actuation signal transfer element, said elongated element being operably fastened at a first end to said cutter, said cutter having cutting means, actuating means for said cutting means actuable upon receiving an actuation signal, a coupling device at a second end of said elongated element, said coupling device having two sections, a first section of said coupling device being fixedly attached to the elongated element and a second section of said coupling device being readily removable from the first section, said second section including an actuation signal initiator and a time delay element to transfer the initiated actuation signal from the signal initiator to the elongated actuation signal transfer element, said second section being readily replaceable and removable from said first section whereby second sections of different time delays can be interchanged on said first section.

2. The combination as specified in claim 1 wherein said actuating means for said cutter is comprised as a pyrotechnic member, said time delay element including a burnable pyrotechnic member of predetermined length which can be changed in different second sections to change the length of the time delay.

3. The combination as specified in claim 1 wherein the line comprises a reefing line for partially reefing a cargo carrying parachute, said cutter being attached to said parachute, and said elongated element extending a sufficient distance so that said coupling device protrudes from the parachute package when the cargo carrying parachute is in folded condition.

4. The combination as specified in claim 3 wherein said actuation signal initiator includes a percussion detonation device, and mechanical actuator means extending out of said second section for firing said detonation device.

5. The combination as specified in claim 2 wherein the second section includes an interior spool mounting member, said pyrotechnic member comprising said time delay element being wound onto the spool and having one end in operative communication with said actuation signal initiator and the other end thereof in operative communication with said elongated actuation signal transfer element.

6. The combination as specified in claim 4 wherein said mechanical actuator means comprises a slidable pin, means to connect said slidable pin to a static line of the cargo carrying parachute, said pin actuating said detonation device upon receipt of motion transferred to it when the static line of the parachute is pulled.

7. The combination as specified in claim 4 wherein said detonation device further includes a linearly slidable firing pin mounted for movement with respect to the second section, interlocking means between said firing pin and said mechanical actuator means, said interlocking means being releasable when said mechanical actuator means has moved sufficiently far so the interlocking means clears said second section thereby to release said firing pin.

8. The combination as specified in claim 7 and aligning cross holes in said second section and said mechanical actuator means, and a safety pin adapted to be inserted through said aligning cross holes to prevent movement of said mechanical actuator means when said safety pin is in place.

9. The combination specified in claim 8 wherein said elongated element is encased with an elastomeric material substantially unaffected by atmospheric conditions.

References Cited UNITED STATES PATENTS 2,581,645 1/1952 Frieder et al. 244-149 2,996,989 8/1961 Grandy 102-70 3,362,664 l/1968 McElroy 244-138 FOREIGN PATENTS 819,696 9/1959 Great Britain.

MILTON BUCHLER, Primary Examiner.

RICHARD A. DORNON, Assistant Examiner.