US3549111A - Aerial personnel recovery apparatus - Google Patents

Description

J United States Patent 11113,5

[ 72] Inventor Fred B. Stencel [56] References Cited Asheville, UNITED STATES PATENTS 9.? K 3 3,103,331 9/1963 Stencel 244/122 gf 3,356,320 12/1967 Webb 244/122 9 [73] Assignee Stencel Aero Engineering Corporation FOREIGN PATENTS Arden, N.C. 585,274 2/1947 Great Britain 244/122 a corporation of North Carolina Primary Examiner-Trygve M. Blix Assistant Examiner-Jeffrey L. F orman Attorney-Roylance, Abrams, Kruger, Berdo & Kaul [54] i f ggsg g f APPARATUS ABSTRACT: In an apparatus comprising an ejection seat, a mm g g snubbing arrangement is provided for positively decelerating [52] US. Cl 244/122 the seat, with automatic release of the occupant restraint har- [51 Int. Cl. 864d 25/10 ness or belt just prior to seat deceleration, to accomplish posi- Field of Search 244/122 tive separation of the occupant from the seat.

,PATENIEU 05022197 3 35491111 SHEET 1 [IF 4 INVENTOR FRED B. STENCEL PATENTED [1532211711 1 35491111 SHEET 2 OF 4 INVENTOR Heep B. STENCEL PATENTEU DECZZIQTU 315 1 11 SHEET 3 [IF 4 lllllllllnllllllllllll INVENTOR Feeo B. STENCEL PATENTEB UEE22I97U 8,549,111

SHEET 0F 4 ZNVENTOR FRED B. STE/V051.

ATTORNEKS' AERIAL PERSONNEL RECOVERY APPARATUS This invention relates to aerial personnel recovery apparatus of the ejection seat type, and more particularly to improved means for accomplishing positive seat-man separation in such apparatus.

It is common practice, particularly in military air craft, to employ seats which can be forcibly ejected from the aircraft in case of emergency, the occupant of the seat being initially restrained, as by a harness or belt secured to the seat, with the restraining means being releasable so that the occupant can be separated from the seat and recovered by parachute. To assure proper operation of the personnel parachute, it is necessary in such apparatus to provide some way in which the occupant can be separated positively from the seat in a fashion such that, when the occupants parachute is called into play, the seat and any equipment related to the seat cannot interfere with the parachute. Though prior art workers have proposed various arrangements to accomplish such positive separation, none has proved entirely satisfactory.

It is accordingly a general object of the invention to provide for more positive and dependable seat-man separation in aerial personnel recovery apparatus of the type described.

Another object is to devise an aerial recovery apparatus of the ejection seat type in which separation of the occupant from the seat is accomplished positively and automatically at a time when the seat is in a predetermined attitude with respect to its projected flight.

A further object is to devise such an apparatus which provides for the automatic sequence of release of the restraining harness or belt and controlled deceleration of the seat.

Broadly stated, the invention applies to apparatus comprising a seat, a power device for ejecting the seat, and releasable restraint means for securing the occupant to the seat, and provides snubbing line means attached to the seat and the aircraft and having an effective length such as to become fully taut only after the seat has reached a predetermined position relative to its original position in the aircraft, an actuator connected to the restraint means to release the same, and means connecting the snubbing line means to operate the actuator at a time just before the seat is decelerated by the snubbing line means, such deceleration of the seat, with the occupant restraining means having been released, resulting in positive seatman separation in a safe fashion.

In order that the manner in which the foregoing and other objects are attained according to the invention can be more fully understood, particularly advantageous embodiments thereof will be described in detail with reference .to the accompanying drawings, which form a part of this specification, and wherein:

FIG. 1 is a semidiagrammatic side elevational view of a recovery system according to one embodiment of the invention, showing parts of the apparatus in the relative positions occupied immediately after ejection of the seat;

FIG. 2 is a semidiagrammatic rear elevational view of the seat with parts occupying the same positions as in FIG. 1;

FIGS. 3 and 4 are views corresponding to FIGS. 1 and 2, respectively, but showing the apparatus at a stage immediately after abrupt deceleration of the seat has occurred;

FIG. 5 is a fragmentary rear elevational view of the seat of FIGS. l--4, with parts broken away for clarity;

6 is a fragmentary side elevational view of the seat, with parts broken away for clarity;

FIG. 7 is an elevational view, with parts broken away for clarity, illustrating the manner in which the snubbing lines of the apparatus of FIGS. 1-6 can be secured to the aircraft;

FIG. 8 is an elevational view of a snubbing cable assembly employed in the apparatus of FIGS. 16;

FIG. 9 is a view similar to FIG. 1, illustrating another embodiment of the invention; I

FIG. 10 is a view, similar to FIG. 3, showing the apparatus of FIG. 9; and I FIG. 11 is a semidiagrammatic side elevational view illustrating yet another embodiment of the invention.

Turning now to the drawings in detail, FIGS. 1-8 illustrate an embodiment of the invention applied to a rocket-projected ejection seat equipped with a slip line-and-brake stabilizing device of the type disclosed in my U.S. Pat. No. 3,103,331, issued Sept. l0, 1963, and in copending application Serial No. 499, 867, filed Oct. 21, 1965, by Todd S. Bradfield et al., now U.S. Pat. No. 3,387,803. The seat is indicated generally at 1 and is equipped with a catapult 2, which can be of the type disclosed in copending application Serial No. 708,702, filed Feb. 27, 1968, by James W. Duncan et al. and at least one projection rocket 3. A harness 4 is provided, and is equipped with a conventional three-point disconnect 5 for releasing the harness so that it no longer secures the occupant M to the seat 1. The seat 1 is mounted in any suitable fashion in the cockpit C of the aircraft A, FIG. 1.

The slip line-and-brake device includes two brake assemblies'6, FIGS. 1 and 6, each of the brake assemblies being mounted beneath seat 1 at a different side thereof. The slip line includes four lengths of nylon or equivalent cord stored in pouches 7, extending thence through the corresponding brake assembly 6, then through the guide 8 of bridle 9, and thence to a securing bracket 10 mounted on the floor of the cockpit C. The four cords making up the slip line have free ends stowed in the pouches 7. Accordingly, with the slip line extending as indicated diagrammatically at 11, FIG. 1, ejection and pro jection of the seat 1 away from the aircraft will cause the slip line to be drawn through the brake assemblies 6, with the result that a stabilizing force is applied to the seat via bridle 9, the free ends of the cords making up the slip line all escaping simultaneously from the brake assemblies 6 when the seat has travelled in its projected flight a distance greater than the effective length of the slip line. Such escape of the slip line from the brake assemblies terminates the stabilizing effect of the slip line-and-brake device. In this embodiment, the snubbing line is made up to two equal lengths of nylon or equivalently resilient cord 12, the two snubbing line cords being of equal length, and one end of each cord being secured to the aircraft by bracket 10. The two snubbing line cords 12 are initially stowed in the respective pouches 13, these pouches being rigidly secured to seat 1, as by brackets 14, FIG. 6.

The free end portions of snubbing line cords 12 extend from pouches 13 for attachment each to a different end of the snubbing line cable 15. As seen in detail in FIG. 8, such attachment is accomplished by means of a shear link 16 comprising two side plates 17 interconnected by pins or rivets 18, one of which is shearable. The end portion 12a of the respective snubbing line cord is tied about one of the pins 18 and the other of the pins 18 passes through aligned apertures in the ends of a clevis 19 which has a portion slidably engaged with a ball 20 rigidly affixed to the corresponding end of cable 15. Attachment of the other snubbing line cord 12 to the other end of cable 15 is accomplished in precisely the same fashion just described. Cable 15 passes in series through a first guide bushing 21, a lever-attachment bracket 22, the shearable portion 23 of a securing bracket 24, and a second guide bushing 21. Two stop balls 25 are swaged to the cable 15, each between a different one of the guide bushings 21 and the corresponding end of the cable. Cable 15 can be of any metallic construction, so long as the cable is capable of withstanding the tensile forces involved in operation of the apparatus and is highly flexible.

As seen in FIGS. 5 and 6, the two guide bushings 21 extend through spaced, parallel members 26 which form part of the bottom of the ejection seat 1 and extend transversely thereof in a location just in front of the seat back. Guide bushings 21 are secured rigidly in place by nuts 27 cooperating with the threaded end portions of the bushings. Considering the seat bottom as presenting a plane of reference, the two guide bushings are parallel and in upright position. The lever-attaching bracket 22 is pivotally mounted on the free end of a lever 28 mounted on the seat back, as by a stud 29, FIG. 5, for pivotal movement about an axis which is located on a line extending midway between and arallel with the two guide bushings 21. Lever 28 is pivotab e between an initial position,

shown in solid lines in FlG. 5, and an actuated position, shown in broken lines in FIG. 5. Securing bracket 24 is rigidly mounted on one of the side members of the seat back and projects inwardly toward the center of the seat back, as seen in H6. 5.

When the lever 28 is in its initial position, the free end thereof, and therefore attaching bracket 22, are disposed near the shearable portion 23 of bracket 24. Under these circumstances, the cable 15 extends through the one of bushings 21 which is nearer bracket 24, then through shearable portion 23 of that bracket, then through the attaching bracket 22 carried by lever 28, and thence through the other guide bushing 21. Assuming the seat to be in a normally upright position, the two end portions of cable 15 carrying the stop balls 25, clevises l9, and shear links 16, depend below the guide bushings 21.

The combination of catapult 2 and projection rocket 3 provides an ejection impulse adequate to assure that the seat 1 will be projected away from the aircraft through a distance which is significantly greater than the effective length of the snubbing line. Accordingly, once ejection and projection of the seat have been accomplished, the snubbing line will become taut, as illustrated in FIGS. 3 and 4. As the snubbing line approaches a fully taut condition, the two cords 12 which make up the snubbing line apply equal withdrawing forces to the two end portions of cable 15, so that the cable is withdrawn through guide bushings 21. Such withdrawal causes a shearing force to be applied to portion 23 of bracket 24, so that the cable is freed from bracket 24. With the withdrawal of the cable 15 continuing, lever 28 is forced to swing in a counterclockwise fashion until it reaches the position shown in broken lines in FIG. and is aligned parallel with the bushings 21. The bracket 22, which serves to attach cable to lever 28, is not shearable. Accordingly, the snubbing line becomes completely taut and applies a force to seat. 1, acting through lever 28, so that the seat is rapidly decelerated. Shear links 16 are so designed as to withstand a force of magnitude adequate to accomplish the desired rapid deceleration of the seat. However, the thrust developed by projection rocket 3 is excessive in that regard, and, with the seat having been decelerated adequately to assure positive seat-man separation, links 16 shear, freeing the seat from the aircraft.

Lever 28 is operatively connected to the pull-type release pin of the three-point disconnect 5. The arrangement is such that, so long as lever 28 is in its initial position, as seen in solid lines in FIG. 5, no withdrawal force is applied to the release pin of the three-point disconnect, and the harness 4 accordingly remains effective to secure occupant M to the seat 1. However, when lever 28 is pivoted to the actuated position shown in broken lines in FIG. 5, this movement is transferred to the release pin to withdraw the same, causing the threepoint disconnect 5 to release the harness, so that occupant M is free to continue in his projected flight once seat 1 has been abruptly decelerated by action of the snubbing line. Since snubbing of the seat cannot occur in positive fashion until lever 28 reaches its final actuated position, release of harness 4 is completed just prior to occurrence of the abrupt snubbing action.

The snubbing line cords 12 and cable 15 are of such length that the efiective length of the snubbing line is significantly greater than the effective length of slip line 11. Accordingly, the snubbing line accomplishes abrupt deceleration of seat 1, resulting in positive seat-man separation, immediately after the slip line has escaped through the brake assemblies 6. The snubbing action therefore occurs at that time when the seat has been fully stabilized by the slip line-and-brake device, but with the slip line being free so as to cause no interference with the snubbing action.

As seen in FIG. 7, bracket 10 comprises a fixed portion 30 which is secured to transverse frame members 31, 32 of the aircraft, as by bolts 33. Bracket portion 30 includes two spaced upstanding ears 34. A swingable portion 35 of the securing bracket includes spaced legs 36 slidably disposed each on the outer side of a different one of the ears 34. A

retaining pin 37 extends through aligned openings in ears 34 and legs 36, so that bracket portion 35 can be pivoted, relative to fixed portion 30, about the axis afforded by pin 37. Bracket portion 35 is generally A-shaped in plan, and the slip line and snubbing line are looped therearound, as shown. Accordingly, bracket 10 serves to securely anchor both the slip line and the snubbing line to the floor of the cockpit.

In the embodiment just described, use of a snubbing line comprising the two cords 12 and the flexible cable 15 serves not only to provide a simple and dependable way to actuate the lever 28 for release of the harness, but also to afford redundancy with regard to the snubbing action. It is to be noted that the bores presented by guide bushings 21 are smaller than the diameter of the stop balls 25, so that neither of the stop balls can pass upwardly through its respective adjacent guide bushing. Accordingly, should one of the two cords 12 be severed accidentally, as conceivably could occur during ejection of the seat from the cockpit, the remaining cord 12'will serve to provide the abrupt seat-snubbing action.

In this embodiment, the shearable links 16 are provided to assure that the seat will be freed from the snubbing line, once snubbing has been accomplished. Such freeing of the seat is desirable when the recovery apparatus is used in connection with, for example, an aircraft carrying two side-by-side or otherwise closely adjacent ejection seats. In such an aircraft, ejection of only one of the two seats can be desired, the occupant of the other seat remaining to try to continue to fly the aircraft, and it would not be desirable for the ejected seat to be still connected to the aircraft, by the snubbing line, after one seat has been ejected and the other seat and its occupant still remain in the aircraft.

Turning now to the embodiment of the invention shown in FIGS. 9 and 10, the seat 51 is equipped with a restraining harness or belt 54 having a disconnect 55 of the type actuated by a pyrotechnic initiator, such an initiator being illustrated diagrammatically at 55a.

The snubbing line comprises two nylon or equivalent cords 62 each secured at one end to the cockpit floor by bracket 60. At a point 65, adjacent the other ends of the two cords 62, the cords are securely fastened together in a manner to prevent slippage of one cord relative to the other. Beyond point 65, the portion 620 of one of the two snubbing line cords is significantly shorter than the portion 62b of the other cord. The shorter portion 62a extends directly to the firing device of initiator 55a and, therefore, serves as a lanyard to fire the initiator when the snubbing line has paid out to such an extent that portion 62a becomes taut. The longer portion 62b is secured directly to the seat 51. Accordingly, despite the fact that the portion of the snubbing line between point 65 and bracket 60 has been fully paid out, the longer end portion 62b, which determines the total effective length of the snubbing line, does not become taut until after tautening of the shorter portion 62a has served to tire initiator 55a and free the occupant M from the seat.

In this embodiment, the seat is not equipped with any stabilizing device. Accordingly, the total effective length of the snubbing line is made to be on the order of 8-12 feet, so as to accomplish abrupt snubbing of the seat very early in its travel away from the aircraft, before any disturbing moments can develop. With the apparatus designed to accomplish such early snubbing, it is desirable that snubbing be complete, so as to completely stop the travel of the seat and assure that a maximum space is attained between the occupant and the seat as a result of the snubbing action. Typically, the apparatus of this embodiment of the invention will employ no shear elements between the seat and the aircraft, the seat being stopped completely and retained by the snubbing line. Use of a resiliently extensible nylon or like snubbing line is of particular importance in this embodiment of the invention, since stretching of the snubbing line during abrupt deceleration of the ejection seat is followed by a contraction, resulting in the seat being snatched back" from that point at which man-seat separation occurred. Such action increases the positiveness of the man-seat separation.

FIG. 11 illustrates an apparatus generally similar to that of FIGS. 9 and 10 save that snubbing of the seat is accomplished within the aircraft, while the seat is still engaged with its supporting and guiding rails. Here, the ejection seat is indicated generally at 71 and is supported in the cockpit C of aircraft A by a pair of supporting and guiding rails Ila in the manner described in copending application Serial No. 720,650, filed Apr. ll, 1968, by James W. Duncan et al. Thus, the seat can be equipped with runners 71b which slidably engage rails 71a to securely support the seat in its installed position and to slidably guide the seat along the rails during ejection. The seat is provided with a catapult (not shown) but employs no projection rockets.

Seat 71 is further equipped with a restraining harness or belt 74 having a disconnect 7S operated by a pyrotechnic initiator shown diagrammatically at 75a.

As in the embodiment of FIGS. 9 and 10, the snubbing line is made up of two nylon cords 82 each secured at one end to the cockpit floor, as by bracket 80. The cords 82 are securely fastened together at a point 85 adjacent their other ends. Beyond point 85, a shorter end portion 824 of one of the two cords is initially connected to initiator 75a and serves as a lanyard to tire the initiator. The longer end portion 82b of the other cord is secured directly to seat 71. in this embodiment, the snubbing line is relatively short, its length being such that, though the same general sequence of operations occurs as in the embodiment of FIGS. 9 and [0, both firing of' initiator 75a and snubbing of the seat occur when the seat has traversed only such a short distance from the floor that the runners 71b are still engaged with rails Ila. Thus, the effective length of the snubbing line is distinctly less than the length of the rails 71 a.

Snubbing of seat 71 within the cockpit of the aircraft, but after release of disconnect 75 as a result of actuation of initiator 754, provides the desired seat-man separation because of the large ejection impulse afforded by the catapult. Thus, the occupant M of the seat continues to travel the ejection path, as illustrated in FIG. 11, the ejection impulse provided by the usual catapult being adequate to assure that travel of occupant M will continue until the occupant's parachute can be opened free from interference by the aircraft. g

in all of the embodiments of the invention, the snubbing line can be employed either to completely arrest the seat, provid ing a maximum seat-man velocity differential, or to slow the travel of the seat to a speed markedly less than that of the occupant. As a general rule, the extent of snubbing should be such as to provide a relative seat-man separation velocity of at least 15 feet per second.

While particularly advantageous embodiments of the invention have been disclosed for illustrative purposes, it will be understood by those skilled in the art that various changes and modifications can be made therein.

1 claim:

l. in an aerial personnel recovery apparatus of the type comprising a seat power means for supplying an ejecting impulse to the seat, and releasable restraint means for securing the occupant to the seat, the combination of:

snubbing line means comprising at least one snubbing line having one end attached to the seat and securablc at the other end to the aircraft.

said snubbing line means having an effective length such as to become taut only after the seat has travelled a predetermined distance from its initial position in the aircraft but is still within the aircralt;

actuator means connected to the releasable restraint means and operable to release the same to free the occupant from the seat in response to a force applied to said actuator means in a predetermined direction; and

means interconnecting said snubbing line means and said actuator means to apply such force to said actuator means to operate the same for release of the restraint means as said snubbing line means approaches fully taut condition, whereby the restraint means is released only just prior to snubbing of the seat by said snubbing line means, said means interconnecting said snubbing line means and said actuator means comprising a lanyard having one end secured to a point on said at least one snubbing line and the other end operatively connected to said actuator means, the effective length of said lanyard being significantly less than the effective length of that portion of said at least one snubbing line which extends between said point and said one end of said at least one snubbing line.

2. The combination according to claim 1 wherein:

said actuator means comprises a pyrotechnic initiator having a movable operator; and

said lanyard is connected to said movable operator.

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