US2341337A - Airplane pickup mechanism - Google Patents

Description

Feb. 8, 1944. G. T. SMITH 2,341,337

AIRPLANE PICKUP MECHANISM Filed Feb. 14, 1942 3 Sheets-Sheet 1 Feb. 8, 1944. a. T. SMITH AIRPLANE PICKUP MECHANISM 3 Sheets-Sheet 2 Filed Feb. 14. 1942 W M W\. n I... \L E mfi w h m RR h km N %N \h v s u I q. a I I... w N a v :uwn. w m hm a; Q Q M WN n2 9* MW Nh W \h Oh Feb. 8, 1944. GT. SMITH 2,341,337

AIRPLANE PICKUP MECHANISM Filed Feb. 14, 1942 s Sheets-Sheet 5 $125 I l: 5 I Z5 E 11% 66 5 24 Patented Feb. 8, 1944 UNITED STATES PATENT OFFICE 2,341,337 AIRPLANE PICKUP MECHANISM George Tucker Smith, Richmond, Va., assignor to G. Tucker Smith and E. Govan Hill, both of Richmond, Va., as trustees Application February 14, 1942, Serial No. 430,957

29 Claims.

This invention relates to airplane pick-up mechanisms. A number of devices have been developed for the purpose of permitting airplanes to pick up articles or packages without the necessity for landing, the airplane being provided with a hook adapted to engage a loop in a flexible element connected to the article to be picked up and having a portion suspended between supporting masts for engagement by the airplane-carried hook. The most practicable mechanisms of this character employ a catapult automatically releasable by the pulling of the suspended loop by the airplane-carried hook, to project the article in the direction and preferably at the speed of flight of the airplane, the catapult overcoming the inertia of the load and thus preventing the airplane from having to pick up a dead weight load.

Certain prior types of mechanisms of this character depend upon the actual pull of the hook against the loop to directly mechanically release the catapult, and these types are not particularly advantageous in use because of the substantial pull necessary to release the catapult. Other types of devices provide for the releasing of the catapult upon the transmission of a relatively light pulling force against the loop, easily operated electric switches being provided which are operable upon the picking up of the loop by the hook to energize a solenoid to release a catapult latch. Devices of this character are highly advantageous, but they require either the running of long electric lines for supplying the current for the circuit or the use of storage batteries for this purpose mounted in the catapult.

An important object of the present invention is to provide a novel catapult mechanism for use'in conjunction with an airplane-carried pickup hook wherein the releasing of the catapult is efiected very easily upon the picking up of the loop by using a' simple-fluid pressure operated motor for releasing the catapult latch.

A further object is to provide a novel apparatus of this character wherein a simple valve device is operable upon the picking up of the loop for releasing fluid pressure from one end 'of the motor whereby fluid pressure in the other end of the motor will become effective for releasing the catapult latch. A further object is to provide a novel motor in a mechanism of this type wherein any minor leaks which occur through the valve mechanism will have no effect on the operation of the motor,

pressures in opposite ends of the motor remaining automatically balanced so that the releasing of air from one end of the motor upon the picking up of the loop will render the motorinstantaneously effective for releasing the cata-1 pultlatch. .r

; A further object is to provide a novel form of an apparatus of this character wherein a single pressure line supplies pressure to one end of the motor and wherein a leakage port through the pressure responsive element of the motor, serves to admit aid into the other end of the motor to balance pressures therein, the leakage port serving to maintain balanced pressures even if leakage occurs through thevalve device.

Other objects and advantages of the invention will become apparent during the course of the following description.

Inthe drawings I have shown one embodiment of the invention. In this showing:

Figure 1 is a side elevation of the apparatus showing an airplane in flight about to pick up the loop connected to the article,

Figure; 2 is a somewhat enlarged rear end elevation of the catapult mechanism and associated elements,

Figure 3 is an enlarged central vertical longitudinal sectional view through the catapult mechanism, parts being shown in elevation and parts being broken away,

Figure 4 is a transverse vertical sectional view on line 4-4 of Figure 3,

Figure 5 is a plan view of the catapult mechanism and associated elements, v Figure 6 is an enlarged central vertical sectional view through one of the loop supporting masts, parts being shown in elevation, and parts being broken away,

Figure 7 is a sectional view on line 'l--'l of Figure 6, and,

Figure 8 is an enlarged central vertical sectional view through the fluid pressure motor, parts being shown in elevation.

Referring to Figure 1, the numeral l0 desig nates an airplane beneath which is suspended an arm ll carrying a hook I2 at its lower end adapted to pick up the loop, to be referred to later, which is connected to the article or package to be picked up by the airplane. v

The airplane is flown over a catapult mechanism indicated as a whole by the numeral I3, and it is this mechanism which projects the article to prevent the airplane from having to pick up a dead weight load. Referring to Figures 3 and 4, the catapult comprises longitudinally extending upper frame members M at opposite sides thereof, and each of these frame members is provided with a horizontal flange l5, fora purpose. to bedescribed. Lower angle iron frame members l6 alsoare provided and the sides of the apparatus are closed by plates 11 as shown in Figure 4 The forward end of the apparatus, that is, t he left hand-end as viewed in Figure 3, is providedat least with a lower transverse. frame member l8'and an end closure plate l9 secured ac o fthc ad a ent ends oi'the framemembers l4 and I6 and is secured to the transverse frame member [8.

At the rear end of the apparatus transverse angle iron frame members 20 and 21 extend across and are secured to the adjacent ends of the respective pairs of frame members l4 and 16. A relatively heavy end plate member 22 is secured to the transverse members 29 and 2|. The forward end of the apparatus is supported by a caster wheel 23 having swivel connection as at 24 with a bracket 25 suitably secured to the end plate 22 and preferably to the transverse frame members 29 and 2!. A draft connection 26 is preferably provided for the caster wheel 23 to permit the apparatus to be hauled behind a motor vehicle as a trailer. The opposite end of the apparatus is supported by wheels 21 which may be mounted on stub axles 28 secured in any suitable manner (not shown) to the lower frame members It.

Acatapult carriage indicated as a whole by the numeral 29 is provided for receiving and supporting an article 38 to be picked up by an airplane passing over the apparatus. The catapult carriage comprises a suitably shaped receptacle 3| for the article beneath which depends a frame structure 32. This frame structure may be of any suitable specific design and supports wheels 33 at opposite ends and at opposite sides of the carriage for rolling engagement with the flanges l5 whereby these elements act as trackways for the carriage. Referring to Figure 4 it will be noted that the wheels 33 are arranged relatively close to the frame members l4 whereby such members guide the carriage for linear movement. The frame structure 32 of the carriage is providedwith a dependent boss 34 to the lower end of which is connected an elastic shock cord 35 of conventional type. It will become apparent that the present apparatus is not dependent upon any particular means for projecting the carriage but it has been found in practice that shock cords are particularly practicable for this purpose. While a single shock cord has been shown itwill be apparent that any number may be employed depending upon the maximum load which itis desired to project on the carriage.

The shock cord 35 (Figure 3) is connected-as at 36 to one end of a flexible belt 31 which passes around apulley 38. The opposite end of the: belt 3? is adapted to be wound about a drum 39 mounted on a shaft 40. This shaft is mounted iii-bearings 4| supported by a transverse member 42 connected at its ends to the frame members l6; A gear 43, mounted on the shaft 48, meshes with a pinion 44 carried by ashaft 45 also, rtatably supported by the bearings 4|. The shaft 45 projects from the side of the apparatus (Figure 4) and terminates in a polygonal end 46 engageable by an end of a crank arm and a ratchet 41 is engageable with a wheel 48 to prevent reverse rotation of the shaft 45. The means just described forms a Windlass for the winding of the belt 31 to properly tension the shock cord 35, as will be apparent.

A spring pressed detent 49 (Figure 3) is carried'by one end of the carriage 29. This detent is engageable by a hook '50 formed on one end of a bellcrank lever mounted on a shaft 52 supported by a bracket 53 which may be secured to the transverse frame member 20. A coil spring 54 normally urges the bell crank lever 5| to turn in a counter-clockwise direction to maintain the hook 50 in engagement with the detent 49. The lower end of thebell crank lever 51 is connected to one end of a rod 55 which is pulled in a manner to be described to turn the bell crank lever andrelease the catapult carriage.

The releasing of the carriage 29 takes place upon the pulling of a loop 56 by the hook 12 (Figure 1) carried by the airplane. This loop, when in operative position, has downwardly and rearwardly converging portions 51 secured as at 58- to the article 38. The portions 5'1 extend upwardly and forwardly from the carriage 29 and are connected by a transverse portion 59 (Figure 2) supported in a manner to be described by the upper end portions of masts 60.

Each of the masts 6B is preferably formed of relatively light seamless steel tubing and each is supported at its lower end by a mushroom base 6| having a sleeve 62 receiving the lower endof one of the masts which is fixed thereto by a lock screw 63. The lower end of each tubular mast is sealed by a plug 54 (Figure 6). The upper end of each mast is provided with. a valve body 65-. Each valve body 65 has a passage 66 communieating with the interior of the associated mast, and with a passage 61 communicating with the atmosphere. A- rotary valve 68 is mounted in each valve body 66 and is cutaway as at 69: so as to disconnect the ports 68 andv 6'! or to connect these ports together upon the rocking of the valve.

Each valve 68 is provided with an upwardly extending. forked arm 18 receiving arubber or similar thimble H carried by the transverse portion 59 of the loop 56. The use of these thimbles, as will become apparent, is not important but their use is preferred for the reason that they provide sufficient frictional engagement with the forked arms '10 to insure the turning of the latter upon the picking up of the loop 59 by the hook I2. Moreover, the use of the thimbles elimi nates direct wear on the loop 56, which is preferably formed of shock cord. In order to properly support the masts 60 in vertical position and to properly space them each mast is slidable through a sleeve 12 which may rest directly upon the upper end of the adjacent sleeve 62. Each sleeve 12 may be fixed to its associated mast'by a lock screw 13, and each sleeve 12: is carried by the outer end of an arm 14 (Fig ures 2', 4 and.6). Each of these arms is pivoted as at T5 to a bracket l6 connected to the side plates H and frame. members l5 whereby the arms 14 may be swung inwardly to positions adjacent and parallel to the side plates I! when the apparatus is to be moved from one point toanother. Hook braces 11 (Figures 4 and 5) are adapted tohold the arms 14- in. extended positions.

The present invention is provided with novel fluid pressure operated meansfor releasing the catapult latch comprising the elements 49 and 50. Referring to Figures 3 and 8, the numeral 18 designates a fluid pressure motor as a whole comprising casing members 19 and 88 having peripheral flanges 8! between which are clamped the peripheral portion of a flexible diaphragm 82 by means of clamping bolts 83. The diaphragm is preferably provided centrally'thereof with stiffening plates 84 and a rod 85 extendsaxiallythrough the diaphragm and through the plates 84 and is secured with respect to these elements by nuts 86. The diaphragm is provided with a leak port 81 preferably extending through .the plates 84, for a purpose to be described. The rod. 85; ex.-v tends through a bearing 88 carried by the casing I9 and is pivotally connected as at 89 to the adjacent end of the rod 55.

The casing I9 communicates through a conventional pressure regulator valve 99 with a hose or pipe 9| supported with respect to one of the side frame members l6 by clips 92. The hose BI is connected to a fluid pressure tank 93, preferably through a cut off valve 94 (Figure 3). The pressure tank 93 may be supported at one side of the. apparatus in the position shown in Figure 4. It will be apparent that the tank 93 may be charged with fluid under pressure from any source. Its capacity is a number of times that of the fluid pressure motor 18 and the tank may be charged to a pressure several times that which will be used in the motor I8. This ample fluid pressure will be available regardless of any minor leakage through the valves 68, for a substantial period of time.

The motor I8 may be fixed against axial movement by a relatively heavy stud 95 and may be further anchored in position by angular braces 96 (Figure 4) secured at their ends to the frame members I6. casing 89 as shown in Figures 3 and 8.

The casing 99 is provided with a nipple 91 (Figure 8) connected to a T 98 from each branch of which a hose 99 leads to a nipple I 99 tapped into one of the masts 69. Hoses 99 of a flexible nature are employed to permit the masts to be swung about the pivot I (Figure 4) as will be obvious. v 9

Upon the releasing of the catapult carriage the tensioned shock cord 35 will move the car riage toward the left as viewed in Figure 3 with substantial force and at substantial speed. It is preferred that some cushioning means be employed for stopping the carriage adjacent its limit of travel. For this purpose a shock absorber l 9I (Figure 3) is employed, and comprises telescoping tubes I92 and I93 in which a spring I94 is housed. The tube I93 may be secured .to the end plate I9 while the inner end of the tube I92 is engaged by a portion of the carriage.

The operation of the apparatus is as follows:

(Figure 3) The stud 95 is connected to the The apparatus is intended for use where it is desired to pick up mail or other articles or packages at points where no landing field is available, or where it is desired to eliminate the time which would be required for a plane to land, pick up the articles or packages to be transported and then take off. The apparatus is hauled to a suitable spot with the arms I4 folded against the sides of the apparatus. These arms are then swung outwardly to their operative position,

whereupon the masts 69 are ready to be placed in operative position. The article or package to be picked up is placed in the carrier 29 with the loop 56 connected thereto, whereupon the thimbles 1| (Figure 6) are inserted into the forked arms 19. The masts are then set up by sliding their lower ends through the sleeves I2 and into the sleeves 62, the lock screws 63 and I3 preferably being tightened after the masts have beenset up. The valve 94 (Figure 3) may then be opened to admit fluid under pressure from the tank 93 into .the motor casing I9, under the control of the pressure regulator valve 99. Air is preferably used as the pressure fluid, and it will be obvious that as the air flows into the casing I9, the leakage port 8! (Figure '8) permits air to flow into the casing 89 and through the T 98 and into the hoses 99 and masts 69. The leakage port 81, while of limited area, provides means for. balancing pressures throughout the system; includmg the balancing of, pressures on opposite sides of the diaphragm 82.- It will be apparent that when the apparatus is set up as described, the forkedarms I9 (Figure 6) will be in'their vertical positions to maintain the valves 68 closed. It is almost an impossibility to provide valves through which there will not be some minor leakage. In a system of the present character this leakage could become a serious matter, but the provision {of the leakage port 91, prevents the pressure on opposite sides of .the diaphragm 82 from .becoming unbalanced except when the rarticle is to be catapulted.

.When pressures on opposite sides "of the diaphragm 82 become equalized at the desired pressure of operation of the apparatus, the diaphragm 82 will be relatively freely movable except that it cannot be moved rapidly in either direction due to the limited area of the port 81. However, if the latch59 has not been previously placed in engagement: with the detent 49, the parts may be moved to the position necessary to latch the carriage 29 by pulling to the right on the rod 55, (Figure 3). p

The operator will now rotate the shaft 45 by means of a crank applied to the polygonal end 46 thereof, whereupon the Windlass will wind the adjacent end of the belt 3! on the drum 39. The belt 31 is employed for the reason that it is desirable to avoid passing the shock cord 35 around the pulley 39 or around the Windlass drum. When the shock cords have been tensioned to their maximum point, the connection 36 will occupy approximately the position shown in Figure 3. Theapparatusis now ready for operation.

- The airplane which is to pick up the article 39 will fly over the apparatus in the direction indicated in Figure 1 with the hook l2 below the horizontal plane of the loop portion 59 and between the masts 69. Upon the engagement of the hook l2 with the loop portion 59, the latter element will be subjected to a quick pull which will be transmitted to both of the forked arms I9 to result in the turning of one or both of these arms. Inasmuch as it is impossible to perfectly equalize the pulling forces on the arms I9 the apparatus has been designed so that the turning of either of these arms will result in the releasing of the catapult.

Assuming that only one of the arms I9 will have been turned, the associated valve 69 will be turned equally to a position in which the .valve cut-out 69 (Figure 6) affords full communication between the ports 66 and 61. Under such conditions pressure in the associated mast 69 will immediately drop and will result in a corresponding immediate drop in pressure in the motor casing 89 (Figure 8). The rate at which the pressure drops in the casing 89 will be many times greater than can be satisfied by the flow of air through the restricted port 81, and accordingly the air pressure in the casing I9 will immediately move the diaphragm 82 to the left as viewed inFigures 3 and 8, thus pulling on the lower end of the bell crank lever 5| to unlatch the catapult carriage. The tensioned shock cords 35 willthen project the carriage 29 and the article thereon in the direction of travel of the airplane, and the apparatus is so designed that the tension of the shock cords will move the article, when it reaches the discharge end of the appa ratus, at a speed approximating that of the plane. This speed will have been attained approximately at the point where the hook, I2 will have straightened out theloop 56,'and accord ingly the article will be picked'up .without any appreciable'shock on the plane.

-The hook I2 is preferably movable along .the arm H by any suitable meansrforming 'no part of the present invention. By such means the loop may be pulled upwardly'into the plane :together with the package. Accordingly it will-be apparent that the present-apparatus permitsthe picking up of articles or packages of 'weights far above the relatively small weights which can -be picked up without the use of a catapult. It is Well known that only very limited dead weights can be picked up by a moving plane and themesent apparatus greatly increases the weights of articles which can b picked up while at the same time eliminating the transmission to the plane of the shock occurring incident to the picking up of a dead weight load.

Bythe simple expedient of balancing pressures in the system, specifically by the provision of the bleed port 81, it is unnecessary to admit air pressure into both ends of the motor 18. The pressure balancing device referred to not only permits the connection of only one side of the motor to the source of pressure but also automatically compensates for any leakage which might occur through the valves 68.

In connection with the foregoing it Will'be'obvious that without the pressure balancing means described, leakage might occur which could very easily progressively reduce pressure in one end of the fluid pressure motor so as to release the catapult prior to the arrival of the plane. It would then be necessary to re-set the apparatus while the plane circled above awaiting the completion of the re-setting operations. While the use of the pressure tank 93 is not essential its use is preferred. If the system were charged with air under pressure it would be necessary to provide the apparatus with a pressure gage since leakage through the valves 68 might reduce pressure in the system to such a point that there would be insufilcient pressure in the casing 19 to release the catapult upon the picking up of the loop by the hook l2. The pressure tank with the ressure regulator valve 90 aiiords dependable means for maintaining proper operating pressures in the motor at all times. Thus the leak age port 8! will compensate for leakage of air from the system to maintain equalized pressure in the motor 18, while the pressure tank 93 and the pressure regulator valve 90 assure the maintenance in the motor of proper operating pressures.

It is to be understood that the form of the invention herewith shown and described is to be taken as a preferred example of the same and that various changes in the shape, size and arrangement of parts may be resorted to as do not depart from the spirit of the invention or the scope of the subjoined claims.

I claim:

1. In an airplane pick-up mechanism, a catapult having a carriage and a latch operative for holding the carriage against movement, a flexible element connected to an article supported by the carriage, means for supporting the flexible element in a position to be engaged by an airplane-carried element, and fluid pressure operated means for releasing said latch to release the carriage, said last named means having a portion carried by said supporting means and operable upon the picking up of said flexible element by the airplane-carried element. 2. In an airplane pick-up mechanism, a catapult havinga carriage anda latch operative :for holding the carriage against'movement-a flexible element connected to an article'supportedby the carriage, means .for supporting the flexible element in a position to be engaged by an air-: plane-carried element, .a fluid pressure operated device connectedto said latch, and means vfor effecting the energization of said fluid'pressure operated device to release said latch,-said last named:means having a portion carried ;by said supporting means and operable upon the picking up of said flexible element by the airplanecarried r element. a

3. In anairplane pick-up mechanism, a catapult havin a carriage and a latch operativefor holding the carriage against movement, a flexible element connected to an article supported by the carriage, means for supporting the flex ible element in a position to be engaged by an airplane-carried element, a fluid pressure' operated device connected to said latch and having a pressure movable element therein onopposite sides of which pressures are normally balanced, and means operative upon the picking up of said flexible element by the airplane-carried element for unbalancing pressures in said fluid pressure'operated device to release said'latch'. a 4. In an airplane pickup mechanism, a catapult having a carriage and a latch operative for holding the carriage against movement, a flexible element connected to an article supported by the carriage, means for supporting the flexible element in a position to be engaged by an airplane-carried element, a fluid pressure operated device connected to said latch, and valve means carried by said supporting means and operable upon the picking up of said flexible ele-' ment by'the airplane-carried element for effecting energization of said fluid pressure operated device to release said latch.

5. In an airplane pick-up mechanism, a cata pult having a carriage and a latch operative for holding the carriage against movement, aflexible element connected to an article supported by the carriage, means for supporting. the flexible elementin a position to be engaged by an airplane-carried element, a fluid pressure operated device connected. to said latch and having a pressure movable element therein on opposite sides-of which pressures are normally balanced, and valve means operative upon the picking up of said flexible element by said airplane-carried element for unbalancing pressures in said fluid pressure operated device to release said latch.

6. In anairplane pick-up mechanism, a catapult having a carriage and a latch operative for holding the carriage against 'movement, a flexible element connected to an article sup ported by the carriage, means for supporting the flexible element in a position. to be engaged by an airplane-carried element, a fluid pressure operated device connected to said latch, said fluid pressure operated device having a pressure movable member on opposite sides of which balanced non-atmospheric pressure is normally maintained, and means operative upon the picking up of said flexible element by said airplanecarried element for connecting one end of said fluid pressure operated device to the atmosphere to thereby establish differential pressures on opposite sides of said pressure movable element to release said latch.

7. In an airplane pick-up mechanism, a catapulthaving a carriage and a latch operative for holding the carriage against movement, a flexible element connected to an article supported by the carriage, means for supporting the flexible element in a position to be engaged by an airplanecarried element, a fluid pressure operated device connected to said latch, said fluid pressure operated device having a pressure movable member on opposite sides of which balanced nonatmospheric pressure is normally maintained, and a valve device operable upon the picking up of said flexible element by the airplane-carried element for opening one end of said fluid pressure operated device to the atmosphere to thereby establish differential pressures on opposite sides of said pressure movable member to release said latch.

8. In an airplane pick-up mechanism, a catapult having a carriage, means tending to move said carriage in one direction, and a latch operative for holding said carriage against move ment by said means, a flexible element connected to an article supported by the carriage, means for supporting the flexible element in a position to be engaged by an airplane-carried element, a fluid pressure operated device comprising a casing having a pressure movable member therein connected to said latch, the ends of said casing having restricted communication with each other to maintain balanced pressures on opposite sides of said pressure movable memher, the ends of said casing being normally maintained at non-atmospheric pressure, and means operative upon the picking up of said flexible element by the airplane-carried element for opening one end of said casing to substantial communication with the atmosphere to rapidly establish unbalanced pressures on opposite sides of said pressure movable member to release said latch.

9. In an airplane pick-up mechanism, a catapult having a carriage, means tending to move said carriage in one direction, and a latch operative for holding said carriage against movement by said means, a flexible element connected to an article supported by the carriage, means for supporting the flexible element in a position to be engaged by an airplane-carried element, a fluid pressure operated device comprising a casing having a pressure movable member therein connected to said latch, said pressure movable element having a bleed port therethrough to maintain balanced pressures on opposite sides of said pressure movable member, the ends of said casing being normally maintained at non-atmospheric pressure, and means operative upon the picking up of said flexible element by the airplane-carried element for opening one end of said casing to substantial communication with the atmosphere to rapidly establish unbalanced pressures on opposite sides of said pressure movable member to release said latch. b

10. In an airplane pick-up mechanism, a catapult comprising a carriage, a flexible element connected to an article supported by the carriage, means for supporting the flexible element in a position to be engaged by an airplane-carried element, a fluid pressure operated device having a pressure movable member therein on opposite sides of which balanced non-atmospheric pressure is maintained, means operatively connected to said supporting means and operative upon the picking up of said flexible element by the airplane carried element for unbalancing pressures on opposite sides of said pressure movable member to efiect movement of the latter. and means operatively connected to said movable member and operative by movement of said movable member for projecting said carriage.

11. In an airplane pick-up mechanism, a catapult comprising a carriage, a flexible element connected to an article supported by the carr'iage, means for supporting the flexible element in a position to be engaged by an airplane-carried element, a fluid "pressure operated device having a pressure movable member therein, said device being normally subjected to non-atmospheric pressure and having a restricted leakage passage for maintaining such pressure normally balanced on opposite sides of said pressure movable member, means operatively connected to said supporting means and operative upon the picking up of said flexible element by the airplane carried element for unbalancing pressures on op-= posite sides of said pressure movable member to efiect movementof the latter, and means operatively connected'to said movable member and operative by movement of said movable member for projecting said carriage.

12. In an airplane pick-up mechanism, a catapult having a carriage, means tending to move said carriage in one direction, and a latch operative for holdin said carriage against movement by said means, a flexible element connected to an article supported by said carriage, spaced masts for supporting the flexible element with a portion thereof in a position to be engaged by an airplane-carried element, a fluid pressure operated device energizable to release said latch, and a valve carried by the upper end of one of said masts and operative upon the picking up of said flexible element by the airplane-carried element for effecting energization of said fluid pressure-operated device.

l3. Inan airplane pick-up mechanism, a catapult having a carriage, means tending to move said carriage in one direction, and a latch for holding said carriage against movement by said means, a flexible element connected to an article supported by the carriage, a pair of masts one of which is tubular, avalve closing the upper end of said tubular mast and having an arm, a portion of said flexible element being supported by said arm and by the upper end of the other mast in a position to be engaged by an airplane-carried element, and a fluid pressure operated device having a pressure movable member connected to said'latch and normally having balanced non-atmospheric pressure on opposite sides thereof, one end of said fluid pressure operated device communicating with said tubular mast whereby the picking up of said flexible element by the airplane-carried element will turn said arm to open said valve and thus unbalance pressures in said device to move said pressure movable member and release said latch.

14. In an airplane pick-up mechanism, a catapult having a carriage, means tending to move said carriage in one direction, and a latch for holding said carriage against movement by said means, a flexible element connected to an article supported by the carriage, a pair of masts one of which is tubular, a valve closing the upper end of said tubular mast and having an arm, a portion of said flexible element being supported by said arm and by the upper end of the other mast in a position to be engaged by an airplane-carried element, and a fluid pressure to afford substantial communication between said end of said device and the atmosphere to unbalance pressures on opposite sides of said movable member to release said latch.

15. In an airplane pick-up mechanism, a catapult having a carriage, means tending to move said carriage in one direction, and a latch operative for holding the carriage against movement, a flexible element connected to an article supported by the carriage, means for. supportingsaid flexible element in a position to be engaged by an airplane-carried element; a fluid pressure operated device comprising a casing and a pressure movable member therein operative for releasing said latch, means for supplying fluid under super-atmospheric pressure to one end-of said casing, said device-having a restricted leakage passage for normally maintaining both ends of. said casing at balanced pressure, and means operative upon the picking up of said flexible:element by the airplane-carried element for opening one'en'd of saidcasing to the atmosphere to unbalance pressures in said device to thereby effect movement of said pressure movable member to release said latch.

16. In an airplanepick-up mechanism, a catapult having a carriage, means tending to move said carriage in one direction; anda latch operative for holding the carriage against movement, a flexible element connected to an article supported by the carriage, means'for supporting said flexible element in a position to be engaged by an airplane-carried element, a fluid pressure operated device comprising a casing and a pressure movable member therein operative for releasing said latch, means for supplying fluid undersuper-atmospheric pressure to one end of said'casing, said device having a restricted leak age passage for normally maintaining both ends of said casing at balanced pressure, and a valve connected to one end of said-casing and constructed and arranged to be opened upon the picking up of said flexible element by the airplane carried element for opening said last-named end of said casing to the atmosphere to unbalance pressures in said device to thereby efiect movement of said movable member to release said latch.

17. In an airplane pick-up mechanism, a catapult having a carriage, means for moving said carriage in one direction, and a latch operative for holding the carriage against movement, a flexible element connected to an article supported by the carriage, means for supporting said flexible element in a position to be engaged by an airplane-carried element, a fluid pressure operated device comprising a casing and a pressure. movable member therein operative for re leasing said latch, said device having a restricted leakage passage for normally balancing pressures on opposite sides of said movable member, a tank for fluid under pressure, means comprising a pressure regulator valve for admitting fluid'under pressure from said tank to one end of said casing, and means for unbalancing pressures on opposite sides of said pressure movable member to release said latch upon the picking up of said flexible element by the airplane-carried element.

18. In an airplane pick-up mechanism, a catapult having a carriage, means for moving. said carriage in onev direction, and a latch operative for holding the carriage against movement, a flexible element connected to an article supported by the carriage, means for supporting said flexible element in a position to be engaged by an airplane-carried element, a fluid pressure operated device comprising a casing and a: pressure movable member therein operative for releasing said latch, said device having a restricted leakage passage for normallyv balancing pressures on opposite sides of said movable member; a tank for fluid under pressure, means comprising a pressure regulator valve for admitting fluid un der pressure from said tank to one end of said casing, and a valve connected to one end of said casing and constructed and arranged to be opened upon the'picking up of said flexible element by'the airplane-carried element to connect one end of. said casing'to theat-mosphere to unbalance pressures on opposite sides of said pressure movable member to effect movement of the latter and release said latch.

19. In an airplane pick-up mechanism, a catapult comprising a carriage and power means for propelling said carriage; a flexible element connected to an article supported by said carriage, means forsupporting said flexible element in a position to be engaged by an airplane-carried element, a fluid pressure operated device having a pressure movable member therein on opposite sides of which balanced pressure is normally maintained, means operatively connected to said supporting means and operative upon the picking up of said flexible element by-the airplanecarried element for unbalancing pressures on opposite sides of said pressure movable member to effect movement of the latter, and means operatively connected to said: pressure movable memberand to'said power means for rendering thelatter effective for propelling the carriage upon movement of said pressure movable member.

20. In an airplane pick-up mechanism, a catapult comprising a carriage and power means for propelling said carraige, a flexible element connected to an article supported by said carriage, means for supporting said flexible element in a position to be engaged by an airplane-carried element, a fluid pressure oper'ateddevice having a pressure movable member therein, said device being normally subjected to non-atmospheric pressure and having a restricted leakage passage for normally balancing pressures on opposite sides of said pressure movable member, means operatively connected to said supporting means and operative upon the picking upof said flexible element by the airplane-carried element for unbalancing pressures on opposite sides of said pressure movable member to effect movement of the latter, and means operatively connected to said pressure movable member and to said power means for rendering the latter effective for propelling the carriage upon movement of said pressure movable member.

GEORGE TUCKER SMITH;

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