US2898058A - Tow target - Google Patents

Description

Aug.'4, B. E -D'E| MAR 2,898,058

' I TOW TARGET Filed Jan. 20; 1954 Y 5 Sheets-Sheet 1 BRUCE/EDEL MAR;-

INVENT A T TORNEK B. E. DEL MAR Aug. 4; 1959 TOW- TARGET 5 Sheets-Sheet 2 Filed Jan. 20, 1954 BRUCliDEL MR9 INVENTOR.

, ATTORNEY.

B. E. DEL MAR TOW TARGET Aug. 4, 1959 5 Sheets-Sheet 5 Itilllllllllll Ill Filed Jan. 20, 1954 73 BRUCEfDEL MAR,

INVENTOR.

A TTOkNEK Aug. 4, 1959 B. E. DEL MAR 2,898,058

TOW TARGET I Filed Jan, 20,1954 5 Sheets-Sheet 4 BRUCffDE L MAR IN V EN TOR.

ATTORNEY.

B. E. DEL MAR Aug. 4, 1959 TOW TARGET Filed Ja n.

5 Sheets-Sheet 5 Mm I- Mm f m V a U R 8 ATTORNEK lU itsd States I Pat This invention relates ito an aerial target to be towed by aircraft for military training purposes aswell as for carrying out various tests andQexperiments. The inventionis directed toimprovements in such a device to meet 'lcertain problems relating to towing the aerial'target, tracking the' target with radar, releasing the target fromthe towing aircraft, and lowering the released target by parachute.

' With reference to the towing of the aerial target, a

problem to which the invention pertains is the tendency of the target to gain on the towing aircraft'in the course of certain maneuvers of the aircraft, with consequent danger of fouling the .tow cable and possible hazard to the towing aircraft itself. The invention solves this problem by providingthe tow target with automatic brake means that operates to increase the air drag whenever the target tends to gain on the leading aircraft. In this regard, the invention is characterized by the concept of providing brake means that is responsive to changes in the tension of the tow cable and tends to maintain a desirable degree of tension dun'ng flight. One practice of'the invention is further characterized by means to prevent operation of the brake means'until the targetbecomes air-borne. For this purpose means is provided that is efliective to block operation of the brake means in response to contact with the ground and this ground contacting means releases the brake means for operation as soon as the tow target rises from the ground at the'take-oth- The tracking of the target by radar centers on the problem of making the tow target reflect the radar signals to an effective degree. The preferred practice'of the' inv'ention not only provides the towtarget with effective radar reflectors fore and aft, but alsocauses at least o'neof the radar reflectors to rotate continuously in the course of the target'flight. A feature of the invention in this respect is-the concept of causing the rotary reflector to wobble or oscillate on its axis. Such oscillation introduces a desirable cyclic variation in the 7. 2,898,058 Patented Aug. 4,

.2 tow cable to be released fromthe tow target in' response to a radio signal sent from the towing aircraft. In a secondpractice of the invention, additional means is provided to release the tow target in response to the developmentof excessive slack in the tow cable. If

the radio control fails, 'the towing aircraft may be nianeuvered ina manner to cause excessive slack tofdevelop in the tow cable or the tow cable may be released at the towplane end by the "towpilot thus causing au ttr matic release of the tow cable by the target. Thus, the pilot has two methods of remote control at his dispjsal to insure release of the cable from the tow target when desired. v i

For those instances in whichthe target is relatively massive, the inventionprovides a control arrangement in which brake means operates automatically forincrease in drag to reduce the air speed of the target as soon as the target is released from the cable and the parachute opens subsequently -only,after the air speed of the target is reduced to a predetermined magnitude. A feature of the invention in this regard is the concept of using a brake means that responds to reduction of air speedand in responding determinesthe timing'of the parachute release. v

A further feature of the invention'is the provision of automatic means to disconnect the parachute completely-when the tow target reaches thegroundw Such provision prevents the parachute from dragging the target along the ground in a strong wind with damaging efiect. The automatic means is adapted to respond to contact with the ground at the end of a flight, anamcorporates a safeguard against disconnecting the parachute from the tow target in response to contactwith the ground prior to take-off.

\ The various features and advantages of the invention willbe apparent from the following'detailed description, considered with the accompanying drawings.

In the drawings, which are to be regarded as merely illustrative:

Figure 1 is a plan view of a selected embodiment of the invention with portions broken away to reveal'concealed structure; b

Figure 2 is a front elevation of thev device shown in 4 Figure 1;

orientation of the reflecting surfaces which not only makes it easy to locate the target by radar, but also introduces a signal frequency that identifies the target among other detected objects.

Asfor the problem of releasing the target from-ith e' towing'aircraft at the end of a flight, it is desirable'ffir of all-to provide a reliable arrangement for releasing 1- the tow target fromtthe tow cable and to open th parachute to lower the target to groundwithout darnage. In one practiceof the invention, a system ofradio controlis provided which makes it possible to cause the embodiment of the invention;

Figure 12 is a view in longitudinal section of a cable- Figure 3 is a side elevation of the same device; I b Figure 4 is a fragmentary longitudinal section through the same embodiment of the invention; v

Figure 5 is a transversesection taken as indicated by the line 5-5 of Figure to show the construction of the forward reflector for radar signals;

Figure 6 is a perspective view of a metal assembly incorporated in the forward reflector;

Figure 7 is a fragmentary plan view on a larger scale of this first embodiment of the invention with portions broken awayto reveal concealed structure; 'Figure 8 is a transverse section taken as indicated by the line 8 8 of Figure-7;

. V .Figure 9 is a transverse section taken as indicated by the line 9-9 of Figure 7; I Figure 10 is a side elevation of; a brake means incorporated in the first embodiment ofthe invention;

'4 Figure 11 is a longitudinal sectional *view of a second engaging means incorporated in the second embodiment of the invention, the cable-engagingmeans being shown in its normal position;

Figure 13 is a similar view of the cable-engaging means in a second position;

Figure 14 is a fragmentary view illustrating a camming action involved in the operation of the second embodiment of the invention;

Figure 15 is a fragmentary plan view of the portion of the cable engaging means shown in Figure 14; and

Figure 16 is an enlargement of a portion of Figure 11 showing ajreleasableconnection for the parachute carriedb the tow target. r 1

' T he invention is applicable to any type of aerial target device that is adapted to be towed by means of a cable fromf an aircraft and which is of such character and value 'asf'to'warrant recovery by parachute for re-use. In the first embodiment of the invention that has been selected byway of example, the tow target has a hollow "body 'or fuselage, generally designated by numeral 20, which is of triangular configuration in plan and provides adequate aerodynamic surfaces to make'the device selfsustaining when drawn through the air at appreciable "velocity by a'tow cable 21.

A The aerial target device has a forward skid 22 for ground contact and has a pair of rear vertical stabilizers 23, the lower edges of which carry additional skids 24 for ground contact. Preferably the target has a nose member, generally designated by numeral 25, which is constructed to serve as a reflector for radar signals and has a reflector member 26 near its trailing edge for the same purpose.

"'Asbest shownin'Figure 6, the nose member 25 includes an integral metal reflector assembly comprising an axial tube 30, a vertical transverse disc 31 on the rear end of the tube and four vanes 32 that are mounted radially on the tube. The disc and the four vanes conform to three planes that intersect at the center of the disc, the three planes being perpendicular to each other." This metal assembly forms four quadrant spaces which are occupied respectively by four bodies 33 of plastic material, the four bodies being shaped to give 'the nose'member a generally conical configuration.

The'reflector member 26 on the trailing end of the tow target has the configuration of threeintersecting discs that are perpendicular to each other and are concentric to "a common center. This reflector member 26 is mounted on a suitable shaft 34 that rotates in a pair of bearings 35; The shaft 34 may be operated in any suitable manner during flight. In this instance, the reflector member 26 and the shaft 34 are mounted in a streamlinedlhousing 36 and the shaft 34 carries a rear spinner 37 having suitably angled vanes to function as an air screw for rotation .of the shaft in response to the slip stream. Preferably the reflector member 26 ismounted on the shaft 34 in a position out of alignment with the shaft axis so that the reflector member wobbles or oscillates when rotated by the shaft.

A feature of the first embodiment of the invention is that the tow target is provided with brake means to increase the drag of the target whenever slack tends to develop in the cable 21, the brake means being responsive to changes in the tension of the cable. Such an automatic brake means may comprise, for example, a pair of rectangular members 40 that normally lie within the configuration of the fuselage 20, as shown in Figure 8, but are adapted to rotate to positions extending into the air stream, as shown in Figures 2 and 8, for increasing the drag on the flying target. The two rectangular brake members 40 may be mounted on two corresponding longitudinal shafts 41 and the fuselage may be provided with upper slots 42 and lower slots 43 to permit the desired rotation of the two members. Each of'the two shafts 41 is mounted in a pair of bearings 44 and carries a rearward rocker arm 46 (Figure 8), and these two 4 1 Y arms are interconnected by a coiled spring 48. Thus, the coiled spring 48 tends to rotate the two shafts in opposite rotary directions to rotate the two brake members from their normal retracted positions to their effective positions at which the bottom wall of the fuselage serves as stop means to limit the spring-actuated rotation of the two members. Each of the twosh-afts 41 carries a control arm 50 on its forward end as shown in the Figures 4 and 7.

A further feature of this first embodiment of the invention is the provision of a second brake means effec' tive to decelerate the tow target as soon as the target is released from the tow cable. This second brake means may comprise a forward door-like member 54 (Figure 1) that is pivotally mounted on the target by an angular rod 55. 1

In addition to these two brake means, the tow target is providedwith a parachute58 that normally lies folded in a rearward parachute compartment 59 as best' shown in Figure 4, the parachute being connected to a suitable fitting 60 that is permanently attached inside thecompartment. The parachute 58 is confined in the compartment 59 by a pair of doors 61 and 62, that are mounted on suitable hinges 63. As best shown in Figure 1, the door 62 has a pair of tongues 67 on its swinging edge which overlie the swinging edge of the door'61 fat the closed positions of the tWO j dQOI'S. Thus, both of the doors 61 and 62 may be held in closed position by suitable latch means in engagement with the door 62. The required latch means may comprise a latch pin 64 that is slidingly mounted in a bushing 65 in engagement with an apertured ear 66 (Figures 4 and 9) that extends downward from the door 62. Suitable means is provided to force the two parachute doors whenever thelatch pin 64 is withdrawn. For example, as shown in,Figure 9, each of the two doors '61 and 62 may be providedwith an operating arm 68 and the two arms may be interconating the two brake members 40 in response to reducnected by a spring 69 that supplies the door-opening force. V

Any suitable arrangement may be provided for oper.-

tionof tension in the tow cable 21 and any suitable are rangement may beprovided for releasing the tow target from the cable 21 and for immediately thereafter operatingthe triangular brake member 54 and, with suitable time delay, opening the two doors'61 and 62 to release the parachute to open for carrying the tow target to the ground. In this particular embodiment of the invention, for example, the cable 21 is yieldingly connected with the tow target for automatic actuation of the two brake members 40; a radio-controlled .motor means, is provided to initiate operation of the triangular brake member 54; and the latch pin 64 for releasing the para? chute is made responsive to the operation of the triangular brake memberg In the particular construction shown in the drawings, the cable 21 that tows the target is permanently connected to an elongated fitting 70 which is slidingly received in a suitable sleeve 71 that is fixedly mounted in the .pre: viously mentioned axial tube 30 of the nose member 25. The slidable cable member 70 is provided with a spline 72 to prevent rotation while permitting free longitudinal movement. The cable member 70 has a threaded bore-75 at its inner end into which is threaded a cooperating con: necting member 76. The connecting member 76 is connected by aiunivei'sal joint 77 with the shaft 78 of a motor 80 and the motor is suitably mountedfor longitudinal movement. For this purpose the motor is mounted on a base 81 that is free to slide longitudinally in a pair of parallel'channel shaped track members 82. The motor 80.is connected by two cables 85 respectively with the two control arms 50 on the shafts 41 thatcontrol the rectangular brake members 40, the two: cables being in movable engagement with suitable guide pulleys 86.

It is apparent that {the described arrangement oper;

:asoaoss atively connects the slidable "cable member 10 at the end .oftthe cable .21vwith the two control arms 50*that nor- .mally :prevent the spring .48 from operating the two rectangular :brake members 40, the ,two springs acting to ,pull rearward on the cable member 70 in opposition to ,theforward pull, of the tension in the tow cable. Thus when the tow cable is under rsuflicient tension to overcome the spring 48, the two rectangularbrake members -'40, are .at their normal retracted positionsentirely inside the configuration of the tow target; but whenever there is ,a tendency for slack to develop in the cable, the spring ,pulls the slidable cable member-7,0 rearward to operate the two rectangular brake members 40,, the brake mem- 'bers rotating progressively into the air, stream .to 3pm- ;gr,e ssively;:increase drag, in a response to, progressivelvre- =du edte sioa n m w; b .e-,.:n-

1 featureofi, this first embodiment :of the invention is -members' 40against operation while thetowtarget is on the ground prior ;to 'takeofi. ,For this purpose a suitable angular-latch member 88 may be mounted ona pivot pin 89in slot 90 in the forward skid 22. Prior to take-off, the latchmember 88 rests on the ground as shown in Figure 4 with the :upwardly extending end .91 of the latch mernber engagingthe motor, base 81 to hold the motor 80 in a forward position in opposition to the two brake actuating springs 47 and 48. V

The pur'poseof the motor 80 is to unscrew the con-' nect'ing member 76 from/the slide member 70 for re- ,lease of ,the :tow' cable .and in addition to actuate the triangular brake member 54 and to cause subsequent opening or the parachute 58 fI n the present embodiment of the invention, it .is' contemplated that the motor will be adapted to operate the triangular brake member 54 only after the cable .is released and then the triangular 'brak'e member will in tum cause theparachute to open for lowering the tow target tothe ground.

The angular rod 55 that pivotally carries the triangu- 7 lat brake member .54 has a central offset 94 (Figure 1 ,by -ineans of which it is fixedly connected tothebrake member and one end of .the rod is bentto form an actuating; arm '95. A'suitable coil spring 96 is anchored at one end, as best shown in Figure 10, and at the other end is' connected to the actuating'arm 95 to apply a' constant fbrcedending to'move the triangular brake member 54- about "its" pivot axis to the broken lines inFigure' 10'. p Normallythe triangular brake'member 54 is held in its: down or closedposition .bya'la'tch pin 97 (Figure 4) which is slidingly mounted in a fixed bushing 98 'in engagement with an apertured ear 100 that extends downward from the rear edge of the brake member. A cable 101; which passes over'a guide pulley 102, is connected at one end to the latch pin 97 and is connected at the other endto a'reel '103onthe motor shaft 78. There is suflithat normally holds the two'parachute doors :61 and 62 in closed position. As the triangular brake member 54 approaches its upward limit position with decreasing air speed of the tow target, the cable 101 is pulled taut to withdraw the latch pin 64 as shown in broken in Figure 10. Thus completion of the operating movement of the triangular brake member 54 causes the two doors 61 and 62 to fly open whereupon .the parachute 58 unfolds and opens to lower the released tow target to the ground. I p Various arrangements may be employed to permit remote control of the motor 80-from a control station located either onthe towing aircraft or on the ground. In

thisinstance, it is contemplated that the towtarget will carry a radio-responsive control unit, generally designated. by numeral 110, which includes athermionic. tube 111 and also includes ,a relay (not shown) for opening provision of means to latch the two rectangular: brake upright position .shown' in to' completely unscrew the connecting member 76 from 'the slide member 70 before the cable tightens towithdraw the latch pin 97. When the latch'pin 97*is'with- 'drawn,*the spring 96 acting on theactuating arm 95 "rotatesthe triangular brake member 54 upward to 'the upright position shown in broken lines in Figure 10. Since such' rotation of the brake'member 54 is counter to the ainstream that envelops the tow target, the triangular brake-member moves upward slowly to develop progressively increasing drag and does not complete its upward -movement until the air speed of the tow target is reduced to a predetermined degree. Thus, the triangular brake member not only serves as brakemeans to increase the drag of the tow target, but also serves as sensing means responsive to the air speed of the tow target.

As shown-in Figure 10, a short cable 104 is anchored at one end to an car 105 on the underside of the'triangular brake member 54'and the other end of the cable is connected to the previously mentioned latch pin 64 and closing the circuit of the motor 80. The tow target carries a number of batteries 112 which arevs'uitably scattered. for weight distribution and which serve the purpose of energizing the motor and components of the radio control unit 110. V The manner in which this first embodiment of the invention serves its purpose will be readily understood from the foregoing description. When the tow target is on the ground .prior to take-oil, the ground-contacting latch member 88 is in position to hold the motor 80 in a forward position as shown in Figure 4, thereby maintaining the rectangular brake members 40 intheir inoperativehorizontal positions, When the tow target rises from the ground, the cable 21 is under sufiicient tension to hold themotor 80 slightly forward from the position shown in Figure 4 and the lat-ch member 88 is free to drop OUlI OIf the path of movement of the motor to permit themotor thereafter to move rearward sufficiently for operation of the rectangular brake members 40. v

Whenever the tow target tends to gain on the towing aircraft, the tension of the 'tow cable drops, whereupon the rectangular brake members 40 actuated by'the spring 48 respond in a manner to increase the drag of the tow target and thereby slow down the target to restore the cable tension. When it comes time to release the tow target from the cable 21 at the end of a flight, a radio signal is sent to the radio control unit to cause energizationof the motor 80. The consequent rotation of the motor shaft 78 first results in unscrewing of the connecting member 76 from the slidable cable member 70 to free the cable, the cable Withdrawing the slide memberfrom the tow target. Further rotation of the motor shaft-after the cable is released winds in the cable 95 to withdraw the latch pin 97 for release of the triangular brake member 54. The triangular brake member 54 rises slowly against the air stream to reduce the air speed of the target and eventually, when the air speed drops to a predetermined magnitude, pulls the cable 104 taut to withdraw the latch pin 64 from the rear 66 .to release the two parachute doors 61 and 62. The spring 69 acting on the arms 68 causes the two doors 61 and 62 to fly open whereupon thefolded,

parachute 58 is carried out of the parachute compartment by air currents and opens to lower-the tow target the ground without damage.

The second embodiment of the invention illustratedby Figures 11 to 14 is of the same general character as the first described embodiment and in like manner carries a motor 120, a radio control unit, and the required batteries (not shown) for energizing the motor and radio control unit. The tow target carries a iolded'parachute 122 in a rear parachute compartment 123 that is closed by a single door 124. The door 124 is mounted by hinge:

means 125 at its rearward edge to swing upward and rearward for release of the parachute 122. A suitable latch."

pin 126 that 'is slidingly mounted in a fixed sleeve 1 27 normally engages an apertured ear 128tohold the para} chute door 124 in closed position, the apertured ear extending downward from the dooras shown. V A concealed the air stream, the cable 131 automatically withdraws the retaining pin 130 to permit the parachute to open. The

opened parachute is connected to the-tow target by a forward cable 133 and a pair of rearward cables 134.

The target is towed by a suitable tow cable 139 which v is provided with a metalloop 140 at its end for engagement by the tow target in a suitable releasable manner.

An important feature of this second embodiment of the inventionis that it provides two independent means for release of the cable 139 and opening of the parachute 122 by remote control.

The advantage of such an arrangement is in-the assurance that the tow target will be released and the parachute will open. If one of the remote control arrangements fails, the other one is available. One

method of remote control is provided by the radio control unit in cooperation with the motor 120. The other method of remotecontrol utilizes the tow cable itself, the arrangement being such'that means carried by the tow target target is provided with a forwardly extending movably mounted member 144, which has a range of at least two positions and preferably has a range of three positions.

The movably mounted member 144 is normally held in a first position by the normal tension of the tow cable 139 and is movable from this normal first position through a second position to a third position. The movement of the member 144 from its normal first position to its second position results in mechanical release of the metal loop 140 on the end of the tow cable and the further movement from the second position to the third position, which follows automatically, results in withdrawal of the latch pin 126 for release of the parachute 122. It will be readily appreciated that the member 144 may be mounted in various ways for various kinds of movement through the required range of three positions.

In the construction shown, the member 144 is pivotally mounted by a pivot bolt 145 on a suitable bracket member 146, the bracket member being in turn anchored by a pair of bolts 147. The member 144 extends into a slot 148 on the forward end of the bracket member 146 near a laterally extending stud 150, as may be seen in Figure 12. It is apparent that since the center of gravity of the member 144 isforward of the pivot bolt 145, the member'will tend to drop by gravity from the normal position the member from its normal position through its second position to its third position.

The movably mounted member 144 is formed with a suitable recess on its forward end to receive the metal loop 140 at the end of the tow cable 139 and is formed with a longitudinal slot 156 to house mechanism 140 of the tow cable 139 may comprise a hook member I160mounted on a pivot pin 161, a bell crank in the formofa generally triangular plate member 162 mounted on a pivot pin 163, and a link 164 that interconnects these two members, Normally, the triangular member 162 is held against a suitable stop pin 168 by a relatively light spring 169, one end of which is connected to a pin fixed to member 144 and the other end of which is connected to the link 164.

1 1 As may be seen in Figure 12, the link 164 is connected to the hook member by a pivot 170 and is connected to thetriangular' member 162 by a second pivot 171 and in the normal position of the parts maintained by the spring 1'69,"the pivot 171 is below center, i.e., is below the straight line passing through the upper link pivot 17 0 and *the'pivot pin 163 on which the triangular member 162 is mounted. Thus, any tendency for the'hook memberf-160 to release the cable 140 by clockwise rotation 'as' viewed in-Figure 12, will be blocked in a positive manner since such rotation of the hook member causes the link 164to urge the triangular member 162 against the stop pin 168. On'the other hand, clockwise rotation of the triangular member 162, as viewed in Figure 12, will rotate the hook member 160 clockwise to the released position shown in dotted lines in Figure 12 and in full lines in Figure 13.

An operating member in the form of a cable 175 is connected at one end to the triangular member 162 by a suitable clevis 176. The operating cable 175 passes over a small guide pulley 177 on the movable member 144 and a pair of spaced guide pulleys 178 inside the tow target. The second end of the operating cable 175 is connected to the previously mentioned parachute latch pin 126.

Normally the parts of the described mechanism for engaging the tow cable loop 140 are positioned as shown in full lines in Figure 12, with both ,the hook member 160 and the triangular member 162 rocked forward and with the rear end of the link 164 depressed. Whenever slack develops in the cable 139, the cable will permit the movably mounted member 144 to drop to its second position shown in Figure 13 and, in fact, the cable will add a downward component of force that will tend to move the member 144 to this second position. In addition, the vane 151, in reaction to the air stream, will provide further force tending to move the member 144 downward.

'Since the spring 169 in the mechanism for engaging thetowcable loop 140 is a relatively light spring 'and'le'ss tension in the operating cable 175 is required to overcome the spring 169 than is required to overcome'the concealed spring 129 associated with the parachute latch pin 126, the downward movement of the member 144'in placing the operating cable 175 under tension initially causes the hook member 160 to release the cable. loop 140. Thus the tow cable 139 may be released from the tow target by remote control by maneuvering the towing aircraft in such manner as to develop excessive slack in the tow cable. The same effect may be achieved also by releasing with the weight of the cable pulling the member 144 downward towards its second position.

Preferably, as shown in Figure 13, when the member 144 drops to its second position and thereby actuates the mechanism for releasing the tow cable loop 140, the triangular member 162 is moved into abutment with a stop surface 179 at the end of the slot 156 so that any further downward movement of the member 144 will pull on the operating cable 175 to actuate the parachute latch pin 126 in opposition to the concealed spring 129. Thus, when the member 144 continues to move downward from its second position by gravity and by pressure of the air stream against the vane 151, the member 144 pulls on the ope'rating cable 175 and at a third position of the member 144 lower than the position shown in Figure 13, the member 144 retracts the latch pin 126 sufliciently to release the parachute door 124. l

Figure 14. It can be seen in Figure 14"that when the movably mounted member 144 is tilted upward from its normal substantially horizontal position, the resultant displacement of the pre-flight latch member 180 towards the stud 150 causes the cam surface 183 to slide" along the 'stoppinwith consequent lifting of theilatch member 180 -"t oa higher angle than its normal angle-relative to the movably mounted member'144. 7 1 i As shown in Figure 15, the pivot screw 181 carries a 'spacer sleeve 184 and a friction washer 185 that is' made of suitable resilient material such as-rlibber or leather. The pre-fligh't latch member 180 is mounted between the friction washer 185 and a nut 186 on the outer end of the pivot screw 181, the nut 186 being-tightened to provide suflicient pressure'against the latch member to maintain the latch memberat whatever position it may be placed.

Thus, when the member 144 is tilted upward-tocam the pro-flight latchmember 18 out of its latching position,

the latch member will remain out of'its latching position until manually restoredafterthe flight.

When the tow target is resting on the ground priorito a flight, the pie-flight latch member l80is in engagement with the stop pin'150 to keep the movably mountedmemher 144 from dropping downward away-from its normal position shown in full lines in Figure l2.- InIthe-course of take-off, the tow target is initially: drawn forward on the ground or close to the ground but there is an inevitable upward tugon the tow cable 139 by the towing aircraft as the towing aircraft :climbs to lift the tow target away from the ground. When this upward :tug occurs with the tow cable 139 extendinglupward-from the towzt'arget at'a substantial angle, the 'movably mounted member .144 is swung upward tothe position shownlin Figure 14 and .;the consequent camming' action lifts' thelprewflight .latch member 180 to an inoperative position. laThe latch member 180' remains tilted inthe inoperative position when the movably mounted member144returnstoits normal position as'the tow target levels olf behind the. towing :aircraft." i

*If desired, suitablespring means such as anelastic cord 187 may be added to provide aboosting force-to urge the member 144 downw'ardfrom its second position to its third position. The elastic cord .187, which preferably 'is a Bungee cord, may beconnected at its forward end to the'previously mentionedstop pin 168 and may be 55 connected at its rear end to one of the screws 214 that anchors the bracket 213;. It can be seen that :theelastic cord creates a relatively small moment for downward {rotation of the member 144 when the member. 144 is in its normal position but creates a substantially larger moment. when the member 144 is in the second position shownin'Figure 13.

The motor 120 that'is controlled by the radio control .unit carriesa suitable angulanoperating am. 188 which in turn carries a pulley 189 thatrests against the upper side of the operating cable 175 between the two previously mentioned guide pulleys, 178. When the .motor l is energized by radio control, the operating arm 188'is rotated counter-clockwise as viewedinFig-ure 11 to cause :the. pulley 189 on the end of the arm-to cooperate with the two guide pulleys 178 to form a'loop in the operating cable 175, the. pulley 189 moving downward between the two spaced guide pulleys 178. This action places the operating cable 175 under tension, the first result being 10 release of the tow cable 139 and the-subsequent result being actuation of the latch pin 126 to release the parachute door 124 to permit the parachute 122 to open. 'Thus, the motor 120 ,is capable of operating the hook member 160 and the parachute latch pin 126 .even though .the movably mounted member 144 remains in its normal position with the tow cable 139 under substantial tension.

A further feature of this second embodiment of the invention is the provision of additional means to cause '10 the parachute 122 to be completely disconnected from the tow target as soon as the tow target is carried to the ground by the parachute.- For this purpose the forward parachute cord 133 is connected to a forward release pin 190 and therear two parachute cords 134 areconnected to a pair of'corresponding releasably secured loops 191.

;Each of the two loops 191 is releasably engaged by a corresponding release pin 192 that is mounted in a 'of fixed apertured ears 193. g

The forward release pin 190 of the parachute assembly .20 {is slidingly mounted in a fixed vertical sleeve 196 and, as

best shown in Figure 16, is' recessed at its lower end to form a hook 197. Normally, the release pin 190 extends into an aperture 198 in a latch member 199. The latch .member 199 is carried by a downwardly extending arm .200 that is pivotally mounted on a cross pin 201. The

latch member 199 is connected by a pair of operating cables 202 with the two release pins 192 respectively that engage the loops 191 to anchor the rear cords 134 of the parachute. It is apparent that if the latch member 199 .31 :is shifted forward from its normal position shown in Fig- 11 and 16, the latch member will release the forward r lease pin 190 and will pull on the two cables 202 to release the two loops 191.

Normally the latch member 199 is in the position shown .3 Figure 11, but is adapted to be shifted forward autm .matically for release of the parachute in response to contactby the tow target with the ground. The required automatic release movement of the latch member199 may be provided by a forward angular skid 206 that has 4 .a rearward arm 207 for contact with the ground and an .upwardly extending arm 208 inside the tow target for .shifting the latch member 199. The upwardly extending arm 208 is connected by an operating cable 210 with the arm 200 of the latch member 199 so that rocking movement of the'skid 206 by contact with the ground will pull jthe latch member 199 forward for complete disconnection ,of the parachute 122. The angular skid 206 extends up- ,ward through a slot 211 on the underside of the tow target and is mounted by a pivot 212 on a downward extending 'bra'cket 213.' The bracket 213 is anchored inside the ,tow target by suitable screws 214.

It is apparent that means should be provided to prevent disconnection ofthe parachute by contact of the skid 206 with the ground prior to take-01f. For this purpose, a .link 215 that extends into a slot 216 in. the skid 206 is j connected by apivot pin 217 to the: skid and is connected by a pivot pin'218 to .a triangular plate 220 inside the.

tow target. The triangular plate 220 which is rotatablymounted on a pivot 2,21 normally rests against a stop bar 222'and is'pivotally connected to a rod 223. The rod 223 extends upward through a suitable guide sleeve 224 I and normally abuts against an overhanging forward portion 225 'of the parachutedoor 124. Thus when the parachute 'door 124 is held closed by the latch pin 126, the

rod 223isheld down by the door to cooperate with the stop bar 222 to prevent rotation of the triangular plate 221 and thereby immobilize the skid 206.

It will be noted in Figure 11 that in this locked position of the'triangular plate 220, the link 215 is swung downward with the link pin 218 past center with respect to the line defined by link pin 217 and pivot 221 so that the upward thrust of the skid 196 in response .to ground contact is transmitted to the stop bar 222 rather than to the rod 223. A suitable spring .226 is provided t'o actuation of the'mechanism, including the.hook,160,for 15 urge the triangular plate 220 clockwise as viewed in center.

Figure 11 whenever the parachute door 124 opens thereby to shift the link 218 past center in the opposite direction. Thus the spring 226 rotates the triangular plate 220 suificiently to retract the link 215 past center so that force from the skid through the link will rotate the triangular plate clockwise away from the-stop bar 222. Y The spring 226 is not strong enough-however,

to cause the skid 206 to pull the cable 210 for release of the parachute in the absence of contact by the skid with the ground. a

The manner in which this second embodiment 'of the invention operates may be readily understood. Prior to take-off, the skid 206 makes contact with the ground but isprevented from causing disconnection of the paraengagement with the stud 150 to hold the movably mounted member 144 in its normal horizontal position. During take-off, however, the momentary upward tilt of the member 144 by the upward tug of the tow cable 139 cams the pre-flight latch member to its upper inoperative position.

When it is desired to release the target from the tow cable 139 at the end of a flight, the pilot of the towing aircraft may cause the tow cable to be released either by sending a radio signal to the radio control unit or by releasing the tow cable from the towing aircraft or by maneuvering the aircraft to develop substantial slack in the tow cable 139. If the motor 120 is energized by the radio control unit, the motor will swing the operating arm 188 downward to cause the operating cable 175 first to ratate the hook member 160 to release the tow cable 139 and second to release the parachute latch pin 126.

Instead of following this procedure to release the tow cable 139, the pilot of the towing aircraft may maneuver to cause substantial slack to develop in the tow cable or may release the forward end of the tow cable from the towing aircraft. In either event the movably mounted member 144 will drop from its normal first position to its second position, As the movably mounted member 144 drops to its second position, the operating cable 175 causes the hook member 160 to release the cable loop 140. Under the force of gravity and the added force provided by the vane 151. in the air stream and the elastic cord 187, the movably mounted member 144 continues to drop to its third position and in diong so, pulls on the operating cable 175 to withdraw the latch pin 126 that holds the parachute door closed.

When the parachute door 124 is released by either of the above procedures, it is opened by the air stream and the parachute 122 is drawn into the air stream with subsequent withdrawal of the retaining pin 130 to .permit the parachute to open. The openparachute supports the tow target by the forward parachute cord 133 and the two rearward parachute cords 134. 1 In the meantime, the movement of the parachute door 124 'upward to its open position leaves the rod 223 free for upward movement and the spring 226 rotates the triangular plate 220 sufficiently to shift the link "21S past This action sets the skid 206 for operation to completely disconnect the parachute in. response to contact with the ground.

When the target reaches the ground, the skid 206 is operated by the impact to pull on the cable 210 and thereby shift the latch member 199 forward. The forward shift of the latch member 199 unlatches the forward release pin 190 to disconnect the forward parachute cord 133 from the target and at the same time nection of the parachute from the target prevents the parachute from causing damage by dragging the target along the ground on a windy day.

'My. description in specific detail of selected embodiments of the invention will suggest to those skilled in the art-various changes, substitutions and other departures from my disclosure that properly lie within the spirit and scope of the appended claims.

' I claim:

1. An aerial tow targetadapted for connection with a cable for towing by an aircraft, said target having: spring means to. resist tension in said cable; movably mounted means to releasably connect said spring means with the cable whereby said connecting means moves in response to changes in the cable tension; a first brake means on the tow target to increase the drag thereof, said brake means being responsive to movements of said connecting means to operate when slack develops in the cable; a. second brake means on the tow target to increase the drag thereof; motor means on said tow target to release said cable means and to cause operation of said second brake means; signal-responsive means for energizing said motor means by remote control; and a normally folded parachute adapted to open in response to said signal responsive means to lower the tow target to the ground.

2. A tow target as set forth in claim 1 which includes means to delay opening of the parachute until the air speed of the tow target is reduced after the cable is released.

3. A tow target as set forth in claim 2 in which said second brake means is movable in response to reduction in air speed after the cable is released; and in which saidparachute is operatively connected with said second brake means to open in response to the reduced air speed.

4. An aerial tow target adapted for connection with a cable for towing by an aircraft, said target having: means forreleasably connecting the tow target to the cable; a normally folded parachute to lower the tow target to the ground; aerodynamic brake means on said tow target movable against the air stream from a normal ineffective positioninto the air stream to decelerate the tow target; spring means to exert actuating force on said brake means in the direction to oppose the air stream,

said springmeans being too weak to overcome the resistance of the air stream at high relative velocities of the air stream; means to latch said brake means in its normal ineffective position; remotely controlled means to release said'connecting means to disconnect the tow target from the cable and to release said latch means to permit said spring means to act on said brake means whereby the brake means moves into the air stream in response to reduction in the relative velocity of the air stream; and means to cause the parachute to open in response to the movement of said brake means into the air stream, whereby the parachute opens when the air speed of the tow target is reduced to a predetermined degree.

S. A tow target as set forth in claim 4 which includes additional brake means on the tow target responsive to the tension of said cable'to increase the drag of the tow target in response to the development of slack in the cable.

6. A tow target as set forth in claim 5 which includes means to prevent operation of said additional brake means'in response to contact of the tow target with the ground. 4

7. An aerial tow target adapted for connection with a cable for towing by an aircraft, said target having: connection means for releasably engaging said cable, said connection means being mounted for movement from a normalposition' in engagement with the cable to a second position and releasing the cable in response to movement to the second position, the direction from said normal position "to said second position being a direction to pull on the cable, wherebythe normal tension in the cable 'te nds to maintain said connection means at its normal position; spring means to move said connection means from said normal position to said second position in the absence of tension-of a predetermined magnitude in the cable thereby -to-cause the connection means to release the cable whenever the cable-tension drops below said predetermined magnitude, so that the connection means may be caused to release the cable either by releasing the leading end of the cable to cause drop in the cable tension or by maneuvering thetowing aircraft to develop slack in the tow cable.

8. A tow target as set forth in claim 7 which includes a pre-flight latch means to hold said connection means in its normal position, said latch means being releasable in response to the upward tug of the cable by the aircraft at take-01f.

9. A tow target as set forth in claim 7 in which said connecting means has a surface for exposure to the air stream to develop force tending to move the connecting means to said second position in opposition to the cable tension.

10. A tow target as set forth in claim 7 in which said connecting means is pivotally mounted to rock forward to its second position in response to downward pull of the cable created by the development of slack in the cable.

11. A tow target as set forth in claim 10 in which the center of gravity of said connecting means is forward of its pivot axis whereby the connecting means gravitates to said second position in the absence of substantial tension in said cable.

12. A tow target as set forth in claim 7 which includes remotely controlled means on the two target to cause said connection means to release the cable at either of said positions of the connection means.

13. An aerial tow target adapted for connection with a cable for towing by an aircraft, said target having: connection means for releasably engaging said icable, said connection means being movable in one respect from a normal position through a second position to a third posi tion, said connection means releasing the cable in re sponse to movement from its normal position to its second position, the direction 'of movement of the connec tion means away from its first position being a direction to pull on the cable, said connection means being biased to move from its first position to its third position in the absence of substantial tension in the cable whereby the tow target may be released by maneuvering the towing aircraftto develop slack in the cable; a parachute carried by the tow target to lower the tow target to the ground; means 'to retain the parachute in a normal folded state, said retaining means being releasable in response to movement of said connection means to its third position.

, 14. A tow target as set forth in claim 13 which includes means to disconnect said parachute from the tow target in response to contact of the tow target with the ground.

15. A tow target as set forth in claim 14 which includes remotely controlled means on the tow target to cause said connection means to release the cable and to cause said parachute to open regardless of the position of' said connection means.

:16, 'An aerial tow target adapted for connection with a cable for towing by an aincraft, said target having: means movably mounted on the front end of the tow target, said means being biased to move from a normal .first position through a second position to a third position; a latch mechanism positioned on said movably mounted means for releasably engaging said cable,

vsaid movably mounted means being adapted to mainoneendand connected at its-other end to said latch means to release the latch means in response to movement of said movably mounted means to said second position; and a second operating means interconnecting said movably mounted means and said parachute-releasing means to operate said parachute-releasing means in response to movement of said movably mounted means to its third position. I

17. A tow target as set forth in claim 16 which includes motor means to release said latch means and operate said parachute-releasing means independently of the movements of said movably mounted means; and which includes a signal responsive" means to energize said motor means by remote control. I

18. A tow target as set forth in claim 16 which includes: motor means; a third operating means intencom necting said latch means and said motor means; a fourth operating means interconnecting said parachute-releasing parachute to open; a first operating means anchored at means and said motor means; and means to energize said motor means by remote control to actuate said third and fourth operating means for release of the cable and for opening the parachute.

19. An aerial tow target adapted for connection with a cable for towing by an aircraft, said target having: a rotary radar-reflecting means; and means to rotate said rotary means while the tow target is in flight.

20. A tow target as set forth in claim 19 in which said rotary means is mounted for oscillatory rotary motion.

21. A tow target as set forth in claim 19 in which said means to rotate the rotary means is powered by the air stream adjacent the tow target.

22. An aerial tow target adapted for connection with a cable for towing by an aircraft, said target having: aerodynamic brake means to increase the aerodynamic drag of the tow target; means responsive to changes in the tension of the cable to operate said brake means when slack develops in the cable; and means responsive to contact with the ground to prevent operation of said brake means on take-off until the tow target becomes airborne.

23. An aerial tow target adapted for connection with a cable for towing by an aircraft, said target having: means for releasably connecting the tow target to the cable; a normally folded parachute to lower the tow target to the ground; drag-inducing means to decelerate the tow target; remotely controlled means to release said connecting means and to operate said drag-inducing means; and means to release said parachute in response to deceleration of the tow target to a predetermined degree.

24. A combination as set forth in claim 23 in which said drag-inducing means changes in position in response to reduction of the air speed of the tow target; and in which said means to release the parachute is responsive to change in position of said drag-inducing means for automatic action.

25. An aerial tow target adapted for connection with a cable for towing by an aircraft, said target having: means for releasably connecting the tow target to the cable; radio-responsive means to release said connecting means for freeing the tow target from the cable; and means responsive to slackening of said cable to release said connecting means independently of said radio-responsive means.

26. An aerial tow target adapted for connection with a cable for towing by an aircraft, said target having: a parachute connected to the tow target to lower the tow target to the ground; releasable means normally positioned to retain said parachute in compact form inside the tow target; means to disconnect said parachute from the tow target in response to contact of the tow target with the ground; and means responsive to said releasable means to prevent operation of said disconnecting means prior to the operation of the releasing means.

27. An aerial tow target adapted for connection with a cable for towing by an aircraft, said target having:

15 means for releasably connecting the tow, target to the cable; means to release said connecting means in response to slack in the cable; means to latch said connecting means against release by slack in the cable prior to take off; and means to release said latch means in response to upward tug of the cable at take 011.

References Cited in the file of this patent UNITED STATES PATENTS 1,981,461 Miller Nov. 20, 1934 2,111,889 Doepp Mar. 22, 1938 2,124,867 Akerman July 26, 1938 7 16 Righter et a1. Sept. 30, 1941 Leslie Mar. 19, 1946 1 Fahrney ;Apr. 30, 1946 Griesinger et al. Apr. 29, 1947 Bowles Dec. 9, 1947 lessen Feb. 1, 1949 Beirise Aug. 2, 1949 Carlson Sept. 30, 1952 Fahrney Aug. 18, 1953 FOREIGN PATENTS Great Britain Apr. 22, 1943

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