US2728538A - Hydraulic drive powder catapult - Google Patents

Description

Dec. 27, 1955 B. MAzls 2,728,538

HYDRAULIC DRIVE POWDER CATAPULT Filed Sept. 25, 1953 4 Sheets-Sheet l y 4 'x I II IE @I IISIII Ox I I|IIIII I E III Il IHII S I||Il| Il Il |I n l III| i{Ilh} j \I I l, |'IIII N u: MKII g5 f iIIIII I l l I@ III; L i W r\ I kk N I w I I I 215 II' I||| II )5 IIII II I I I I ,1| I IIIIIIIILIIIQIVI 1N VEN TOR. ERNHRD MAZ/5 H Trae/VE Ys Dec. l27, 1955 B. MAzls 2,728,538

HYDRAULIC DRIVE POWDER CATAPULT Filed Sept. 23, 1955 4 Sheets-Sheet 2 JNVENTOR. 55 MII/zo MHz/5 @dun-IJ.. 751@ Dec. 27, 1955 B. MAzls HYDRAULIC DRIVE POWDER CATAPULT 4 Sheets-Sheet 5 Filed Sept. 23, 1955 INVENTOR. BER/vwo' Maz 1.5

Dec. 27, 1955 B. MAzls HYDRAULIC DRIVE POWDER CATAPULT 4 Sheets-Sheet 4 Filed sept. 25, 195s IN VEN TOR BY K /9 Trai? v5 ys United States Patent@ HYDRAULIC DRIVE POWDER CATAPULT Bernard Mazis, Woodbury Township, Gloucester County, N. J.

Application September 23, 1953, Serial No. 382,016

3 Claims. (Cl. 244-63) (Granted under Title 35, U. S. Code (1952), sec. 266) The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or'therefor.

This invention relates to a propulsion device and more particularly to a hydraulic-drive powder catapult system particularly useful in connection with launching an aircraft or object into space.

At present there are in use several types of launching devices, namely, the compressed-air hydraulic, compressed-air slotted-tube and the powder slotted-tube catapults. However, utilization of the aforementioned devices result in certain disadvantages. The compressedair hydraulic catapult requires large and heavy accumulators for storing oil and air under very high pressures. Such catapult is further limited as to the acceleration rate, maximum speed and power that can be generated, and to relatively long time intervals between recharging or tiring, since to improve any of the above limitations would necessitate a substantial increase in the size, number and weight of pumps needed to improve catapult operation. Undesirable operating features similar to those of the hydraulic catapult are produced by the compressed-air slotted-tube catapult.

The powder slotted-tube catapult requires an extremely heavy frame enclosure built up around the tube to prevent it from opening under high pressure and heat. in addition, a long strip must be provided to seal the slotted tube as the launching piston travels during a stroke. At the completion of a power stroke such sealing strip falls away from the slot causing llames and smoke to shoot out from the tube, thereby necessitating a large cover over the catapult for protection. Rapid tiring cannot be accomplished without providing a complicated cooling system because the split-tube structure does not lend itself to installation of 'a simple cooling jacket about the entire tube. Maintenance and repair of the catalpult can be accomplished only after extensive dismantling of the protective coverings.

it is an object of this invention to provide a catapult apparatus that will overcome the above-stated disadvantages.

Another object of the invention is to provide a compact mechanism of relatively simple construction capable of delivering sufficient energy to catapult an airplane or other object into space.

A further object is to provide in an internal-combustion cylinder means for supplying a cooling liquid to the interior of the cylinder between combustion periods for rapid cooling.

Still another object is to provide in a catapult system braking means for limiting the stroke of the launching piston,

These and other objects of the invention and the various features and details of construction and operation thereof are hereinafter more fully set forth and described with reference to the accompanying drawings in which like numbers refer to like parts.

2,728,538 Patented Dec. 27, 1955 Fig. l is an elevation view in section of the hydraulic powder-catapult mechanism of the invention,

Fig. 2 is an enlarged elevational view in section of the packing gland of Fig. 1,

Fig. 3 is a cross-sectional view of the packing gland taken along line 3-3 of Fig. 2,

Fig. 4 is an elevational view in section of the oatingtype packing included in the packing gland of Fig. 2,

Fig. 5 is a cross-sectional view of the floating-type packing taken along line 5--5 of Fig. 4,

Fig. 6 is a plan-view of a portion of the braking systern employed with the invention of Fig. 1, and

Fig. 7 is an elevational view of the braking system of Fig. 6.

As shown in Fig. l, the device according to the invention consists of two chambers 11 and 13 each having keyways (not shown), both such chambers connected at one end to a U-shaped chamber or elbow 15. Connected to the open end of chamber 11 is a breech or powder chamber 17. Utilization of powder explosives as a motivating force in a catapult is ideal since it is a simple and compact source of power. Forward of breech 17 in the interior of chamber 11 is a keyed breech piston 19, said pistonV adapted for reciprocating movement within the chamber in its keyway. Combustion of a charge in powder chamber 17 exerts a pressure against piston 19 causing the piston to act upon a hydraulic lluid 21, such as a mixture of glycerine and water, contained in chambers 11, 15 and 13 between pistons 19 and 23. A keyed launching piston 23, is situated within the interior of chamber 13 near elbow 15 and is adapted for reciprocating movement within said chamber. Suitably connected to a terminal (not shown) in piston 23 are towing cables 25, said cable being threaded through holes in the wall of elbow 15. The other ends of cables 25 pass through a packing gland 27 to a launching carriage (see Fig. 6).

Packing gland 27 is affixed to the lower portion of elbow 15 and contains self-collapsing packing 29 having thrust bearings 31 and 31 to enable said packing to revolve about cables 25 (see Figs. 2, 4 and 5). Gland 27 also contains baies or compartments 33 having air jets 3S interspaced around the circumference of said baffles and at the bottom points of compartment 33 are drain ports 37. Tubing 38 is attached at one end to packing gland 27, below ports 37 and connected at the other end to a suction pump 39, said pump being connected by tubing 40 to a uid reservoir 41. Stop rings or pins 43 mounted on theinner surfaces of chambers 11 and 13 are adapted to limit the movement of pistons 19 and 23 to the battery and launching positions. A normally open switch 45 is located at the stop position of launching piston 23, said switch being closed when piston 23 bears against stop ring 43. Located at the elbow end of chamber 11 is an automatic solenoidoperated ll valve 47. Said valve 47 is normally closed. When piston 19 is in its forward position after a charge has been tired, valve 47 opens starting pressure pump 55. A solenoid-operated bleed-and-overflow valve 49 is so positioned on chamber 11 that the breech piston must bear against breech stop 43 before fluid can ow through it to reservoir 41. Valve 49 contains a heat-activated switch 51 which operates to cut off pressure pump 55.

ln operation, powder-,is burned in breech 17. The expanding gases produced as a result of thecombustion ot' the charge exert a high pressure against breech piston 19 which in turn acts against the hydraulic iluid 21 confined in chambers 11, 15 and 13. Such pressure is transmitted by the liquid to act on launching piston 23. As the launching piston 23 is urged to travel in chamber 13, towing cables 25 connected to piston 23 move with said piston, thereby actuating a launching carriage (shown schematically in Fig. 6). The travel of launching piston 23 can be stopped and retracted by a hydraulic brake and retracting engine such as is presently used with the slotted-tube powder catapult or by means to be hereinafter discussed in detail. Partial braking (not shown) can also be accomplished by lowering a metering rod into the elbow after launching piston 23'exceeds the launching point. During the firing cycle valves 47 and 49 remain closed, pump 5S is inoperative and switch 45 is opened.

Retraction is accomplished by pulling back on towing cables 25. During retraction fuel valve 47 is opened and pressure purnp 55 is started. Fluid lostfin the packing gland through seepage is replaced. Such lest tluid is collected in packing gland 27 and returned to lluid reservoir 41 by means of suction pump 39, said pump being in continuous operation. Fluid 21 pumped under pressure from reservoir 41 into chamber 11 exerts a pressure against breech piston 19 urging said piston to move to breech stop 43. Pump 55 also replaces any fluid that is vaporized by heat in breech tube 11 after tiring. Valve 49 can be opened at the start of the retraction cycle, but, to prevent hot gases in chamber 11 from entering liuid reservoir 41 through overflow line 57, it is preferable to open valve 49 by a switch (not shown) after piston 19 reaches stop 43. When chambers l1 and 15 are rellcd with duid, excess duid will enter valve Zi9 and return to reservoir 41 for recirculation, thereby acting as a cooling system.

Overflow fluid 21 entering valve i9 activates iloat Sti, which in turn closes switch S1. By suitable circuitry of standard design, switch Si is connected to pressure pump 55 to stop said pump and close valve i7 when said switch 51 is closed. (it is to be noted that instead of lioat Si? closing switch 51 thereby stopping pump 55 and closing valve i7 when said lioat Sil is actuated, oat 5S can actuate a signal lamp (not shown) allowing the fluid to circulate till just prior to the succeeding catapult action, thus providing a means for cooling chamber 11.) When launching piston 23 reaches stop 43 switch 4S electrically connected in series with switch 51 is closed. When switches 45 and 51 are closed, this automatically activates solenoid valve 49 and closes said valve. Float compartment in valve 49 is then drained. After draining, the device is in condition to be retired.

Split ring 29 in the packing gland 27 shown in Pigs. 2, 4 and 5 is used to prevent escape of the hydraulic liuid 21 from elbow 15. Said ring circumscribes the towing cables and prevents leakage of tiuid into gland 2?. The shape of the ring bore 39 is determined by the outer surface of the cables used. As indicated in Fig. 5, bore 30 is designed for wire-rope cables presently used in catapult installations, and is broached as closely as possible to the outer circumference of cables 25. Round cables can be substituted for presently used cables or additional strands of wire-rope can be added to the present cables to round them out. in addition, extra layers of line strand can be wound coilwise around the cables to effect a more easily scaled surface and reduce the amount of leakage.

The split-rings are similar in principle to commercial type of packing used on rotating and reciprocating shafts in the manner in which they arc cut so that they will close inwardly toward the center as they wear, and in the principle that the pressure confined by such rings aids in sealing. Since the pressure acting on the outer circumference of the ring is the same as the pressure acting at the inside diameter or bore and since the area of the outer surface is greater than the area of the inner surface, the eiective force acting to hold the segments against the rope is equal to the diierence in areas multiplied by the pressure.

in the present installation, since the segments are rotating at fairly high speeds, the rings are designed so that the resulting force is suiiicient to overcome the centrilugal force acting to throw them away from the rope. Retaining bearings (not shown) with adjustable positioning and tension means can be used to retain the segments. As the towing cable is pulled during launching and retraction cycles, the packing collapses about cable 25 to seal out any lluid. Thrust bearings 31 and 31 provided with split ring packing 29 enable the packing to rotateY when cable 25 is pulled through it. This rotation results from the spiral or screw shape of the rope. Bearing 31 receives the load during the launching and braking cycle while bearing 31 receives the load during the retraction cycle. Air jet cleaners 35 are operated to blast oli any fluid that -seeps into packing gland 27. Such liuid is sucked out of the gland through ports 37 into line 38 and thence to reservoir 41 by suction pump 39.

The automatic bleed system, whereby the fluid is allowed to circulate in chamber 11, as hereinbefore mentioned, reduces the temperature of the chamber and thus acts as a cooling system to prevent overheating. Said system also replaces tluid vaporized by the heat generated in the interior of the chamber due to combustion in the breech chamber.

Braking of the catapult mechanism can be accomplishcd by apparatus as shown schematically in Figs. 6 and 7. Cylinders 11' and 13 and elbow 15 are similar to cylinders 11 and 13 and elbow 15 respectively, except that instead of cylinders 11 and 13 resting in parallel planes, cylinder 13 is tilted downward at an angle to cylinder 11'. Fluid 63 similar to iiuid 21 is placed in the lower portion of launching cylinder 13' over the length designated as braking run so that piston 23 contacts fluid 63 just prior to the end of the power or launching run of said piston. Trapped air in the braking run section of cylinder 13 can be allowed to escape or can be utilized as a cushion in decelerating the travel of piston 23. Cable 2S extends beyond elbow 15 and is suitably drawn over a series of pulleys 65 and terminated in a terminal block of shuttle 67.

In addition to braking the travel of launching piston 23 after th'e power run shuttle 67 and towing cables 25 must not only be stopped but said Shuttle and cables must be decelerated in such a way that they will produce a drag on piston 23' to maintain cables 25' taut. Attached to the sides of shuttle 67 are cam-shaped elements 69. Said shuttle is adapted for reciprocating movement between guide rails 71 mounted below the deck plate of the flight deck or other launching surface. Disposed on the outer sides of guide rails 71 throughout the braking run are a series of hydraulic cylinders 73. Said cylinders have a piston 75 the head of said piston bearing against a lluid 77. Pivotally attached to the end of piston rod 79 is a friction rail S1. The other end of rail 31 is stationary but pivotable about a pin 83. As shuttle 67 travels through the braking run section along guide rails 71, cam surfaces 69 bear successively against friction rails Si urging piston 75 against fluid 77 thereby compressing said uid. Such action produces a reaction against pistons 75 thereby applying a force through piston rods 79 and friction brakes 81 against cam surfaces 69 retarding the forward motion ot shuttle 67 until the shuttle speed is reduced to zero. This method of friction braking produces the desired results of decelerating shuttle 67 and maintaining cables Z5 taut during the braking cycle.

From the above teachings it is seen that the present device does away with the heavy outer framework required for the slotted-tube type catapult. No cooling system is required except a simple one for the breech chamber. The simplicity of the present structure greatly r reduces the possibility ot any major mechanical failure and eliminates the necessity of considerable disassembly. By varying the ratios of the cross-sectional areas of the chambers, the power and speed ratios between what the powder produces and what is required for launching an airplane or object can be varied. Said device can also make possible more uniform speed and acceleration, regardless of the variations in power produced by the powder or of the varying weights of the objects to be catapulted by the use of check and metering valves.

While a particular embodiment of the invention has been shown and described herein, it is not intended that the invention be limited to such disclosure, but that changes and modiication can be made and incorporated within the scope of the claims. For example, in commercial adaptations of the invention, connecting rods can be attached to the pistons in place of the towing cables and each of the cylinders can be designed, with a head or combustion chamber for use with steam or gasoline in lieu of powder to produce a twin-cylinder pump or compressor with continuous pressure or suction, or to produce a side-by-side rather than an opposed cylinder type reciprocating engine.

What is claimed:

1. In combination, a U-tube having each of its ends extending horizontally and in the same vertical plane, an explosion chamber in one end, a piston next to, and adapted to be moved by an explosion in said chamber, a second piston in the other end, liquid between the pistons and tractive means extending from the second piston, through the liquid and through the walls of the U-tube comprising a wire-rope cable, a packing gland where said cable leaves the U-tube, and air jets in the packing gland to blast oi'r the cable liquid that has escaped the packing.

2. In combination, a U-tube having one of its ends extending horizontally, the other end of said tube extending at an angle to said rst end, an explosion chamber in the horizontal end, a piston next to, and adapted to be moved by an explosion in said chamber, a second piston in the other end, liquid between the pistons and tractive means extending from the second piston through the liquid and through the walls of the U-tube comprising a wire rope-cable, a packing gland where said cable leaves the U-tube, air jets in the gland to blast off the cable liquid that has escaped the packing.

3. In combination with a cylindrical tube having a piston adapted for reciprocating motion therein, liquid means for exerting a pressure on said piston, and tractive means extending from said piston through the liquid and through the wall of said tube comprising a wire-rope cable, a packing gland where said cable leaves the tube, air jets in the gland to blast olf the cable liquid that escapes the packing.

References Cited in the tile of this patent UNITED STATES PATENTS 525,434 Walker Sept. 4, 1894 816,643 Chiles Apr. 3, 1906 1,016,603 Baker Feb. 6, 1912 1,225,702 Davol May 8, 1917 2,289,766 Fieux July 14, 1942 2,373,972 Moreno Apr. 17, 1945 2,489,315 Paulus Nov. 29, 1949

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