US2608134A

US2608134A - Aircraft gun port opening and closing device controlled by gun temperature

Info

Publication number: US2608134A
Application number: US155721A
Authority: US
Inventors: Jr Robert R Beachler; John M Oberholtzer
Original assignee: Individual
Current assignee: Individual
Priority date: 1950-04-13
Filing date: 1950-04-13
Publication date: 1952-08-26
Anticipated expiration: 1969-08-26

Description

R. R. BEACHLER, JR., ETAL Aug. 26, 1952 AIRCRAFT GUN PORT OPENING AND CLOSING DEVICE coNTRoLLED BY GUN TEMPERATURE 2 SHEETS-SHEET 1 Aug 26 1952 R. R. BEACHLER, JR., ET AL 2,608,134

AIRCRAFT GUN PORT OPENING AND CLOSING DEVICE CONTROLLED BY GUN TEMPERATURE Filed April l5, 1950 2 SHEETS--SHEET 2 Patented Aug. 26, 1952 AIRCRAFT GUN PORIT OPENING AND CLOYS- ING DEVICE CONTROLLED BY GUN TEM- PERATURE Robert R.. Beachlex', Jr., Santa Monica, and John M. Oberholtzer, Los Angeles, Calif., assignors to the United States of America as represented by the Secretary of the Air Force Application April `13, 1950, Serial No. 155,721

(c1. ssa-37.5)

4 Claims. 1 In high speed aircraft, it has been found desirable to p-rovide closures for the gun blast tube opening. If such openings were not closed while the guns were not in operation, a serious decrease inaerodynamic efficiency would be caused by the i open ports. On the other hand, if such ports are closed while a cartridge is being red from a gun, serious disruption of the airplane structure may occur, whichmay conceivably lead to the loss of the airplane and: its personnel.

Y One object of the present invention is to' provide a device which `will open the gun ports when the gun mechanism is actuated.

Another object of the invention is to provide a mechanism that will close the gun por-ts after the gun has ceased to lire, but will keep them open so long asthere is any danger of a heat-induced explosive discharge resulting from leaving a cartridge in a hot barrel chamber. Such discharge is commonly known as a cook-off.

Another object of the invention is to provide a device of the above character in which the rate of cooling of the device may be synchronized with the rate of cooling of the gun barrel, particularly the chamber thereof, both when the ship is in the air and when it is on the ground. The two rates of cooling ,are greatly different in such case.

Another object is to provide a device of the above character which does not employ thermocouples. ThermocouplesA have been found to be unreliable inthis kind of duty, due to severe vibrationl to which theguns and other parts of the airplane are subjected.

The present arrangement, briey described, provides such a control wherein an electrical unit comprising a thermal computing relay (Thomas A. Edison, Inc. Model 501) is utilized to simulatev the heating and cooling rates of the guns. The relay has a pair of contacts, which are normally closed, one of which is mounted on a bi-metal strip which is wound with a heating coil. This heater is energized concurrently with the ring of the guns. As ring continues,;the bi-metallic element is heated until contact is broken. Such action de-energizes the door-closing circuit but does not interrupt ring or cease heating the bimetallic element. The heat transfer of the unit occurs at a rate comparable to the cooling of the guns and upon cessation of firing the bi-metallic Ielement cools. Resumption of firing may, however, further heat thebi-metal strip and prolong the cooling period required before the doors will close. In addition to the above mentioned bimetal strip and heater, thexed contact is carried on a second bi-metallic member which compensates for over-alltemperature variations with-i in the unit (not shown). The entire assembly is inclosed in a vacuum-tube-envelope, whereby the desired slow cooling-rate is obtained.

The thermal computing relays of the kind de scribed are included in the system disclosed. One of these is comparable to the ground coolingrate for the guns, while the other is arranged to simulate the cooling-rate Vwhile the aircraft is in the air. The relay contacts are adjusted to open before the gun temperature rises into the critical zone where there is danger of a cook-oli, therefore preventing the door-closing mechanism from being actuated.- These contacts are held open until the dangerhas passed and the temperature has been reduced below a safe limit whereupon the normal actuation of the doors is resumed. An additional time delay relay for power control is provided. It tends Ito minimize the elTects of vibration and marginal contact conditions.

Referring -now to the accompanying drawings, Fig. 1 is a schematic diagram showing the electric circuit through which the objects of the invention are achieved. The relays, switches, etc., are shown in their normal positions i. e. those assumed when no current is flowing in the circuit.

Fig. 2 is a fragmentary View of an airplane in side elevation, to which the invention has been applied. An access doorA is shown open, through which opening the guns may be seen.

I0 is a gun-port door closing actuator or mechanism and Il is a gun-port door opening actuator or mechanism. These are not further described because they are conventional in various forms. One form is illustrated in Patent 2,428,359 as element 86, Figs. '7 and 8 of that patent. In the present ligure, I0 and Il are both grounded but are served by conductors I2 and I3 from sources A and B, respectively. Current flow in conductor I2 is under the immediate control of a relay I4 coil which in turn is under control of a second or thermal element-sensing relay I5 through a lead I6.

The door `opening actuator Il and door closing actuator l0 are. 'under the control of relay Il. The coil I8 of the relay I'I is grounded at I9. Relay coil I8 controls the 0.10 second slow-breakrelay-contacts 2| and simultaneously relay contacts 22 which control respectively the port opening actuator Il and the door closing actuator l0 from sources of D. C. B and A respectively which may be of 28 volts.

The source B of direct current'supplies a. pair of identical

thermal computing relays

25 and 26 which are effective respectively in the air and on CII conditions and the other wound with an electric heater coil, such heaters being indicated at k21 and 28 respectively. The heaters 2l and 23' are ad- ,iusted to heat and cool at the same rate as the gun barrel when the latter is respectively airborne with the airplane or substantially stationary on the ground. The

Contact pairs

29 and 30 are arranged to be normally closed, i. e., when cool and to open when the heaters 27 and 28 have attained a critical temperature.

Source B

supplies contact pairs

29 and 30, respectively, of the parallel-connected

relays

25 and 26 with current whereby to energize relay coil 3|; `The latter-is supplied through leads 32, 33 and`50when the armature 34 of an air-ground transfer relay is on thev ground contact 36 as shown. When the relay armature 34 is in the air position, i. e., in contactvwith terminal 31, at end of lead 38, no ground thermal relay connection is provided.

(B) The airplane is in the air and not ring,

(C) The airplane is in the air ring, and

(D) The airplane is on the ground ring.

Since the last case seldom occurs, description of thecircuit occurrences whichfmake itrpossible will be omitted. The remaining cases are however below described:

(A) The airplane is on the gro-und and not )integr-The relay S5 is closed upwardly by the action of the landing gear on switch 39. Power from source B is applied through the

contacts

30 and 36 of the lead 33 to energize the relay winding 3| of the relay I5, thereby closing the contacts 44 to the right. As a result, power from the source B is applied through the lead I6 to energize the winding Illa of the relay |4 to close the armature thereof and thus to apply power A lswitch 39 is arranged to be open when the Y ship is on the ground orlwhen the landing gear (not shown) is lowered. A- spring 40 is provided t'o return it rto closed position 4when the airplane is inthe air. Ground connection is provided by switch 39 for the relay coil 4|, energizingthe lat-` ter from a third D. C. source C. Heating' current for the heating elements 2l vand 28 of

thermal relays

25 and 26, respectively, is provided. through a lead 43 from source B. Source B is connected to a set of contacts 44 of thel relay l5 through a lead 45. The opening mechanism controlv and powerrelay unit Il is connected to the thermal element sensing relay E5 through the lea-da. A gun-ringrelay 47 may be energized from source B. A gun ring switch 48 is provided to conduct current from source B through thesecond set of contacts 4'9 of the relay l5, lead 46, contacts 2| and lead i3, thereby completing the circuit to the gun port door opening mechanism I.

Referring now to Figure 2, in which actual adaptation of the just described structure to an airplane is shown: In the figure, |00 is the airi plane fuselage in which there is a cabin |0I, containing'a steering wheel |02, on which there is mounted a gun trigger or firing switch 48. The switch 48controls the firing of the machine guns |03, which are mounted in a compartment |04 closable by a door |05. The airplane is provided with a landing gear |06, which is foldable as shown in dashed line at |07, into the wings one of which is |08. The guns |03 are arranged in a partially-shown forward framework or support |09. to4 t into ports which are closable by gun port doors ||0 each covering a gun port H0. Each door ||0 is governed by an actuator IH, which here represents both the opening mechanism and the closing mechanism |0- The relays and other electrical components 'may be contained in a box ||2 which may be mounted inside the gun compartment |04.

Operation from source A through the armature 22 of relay to close the gun port doors by means of the actuator l0.

(B) The airplane is in the air cmi not firing.- In this case the switch 39 is closed by the action of the spring 40 thereby energizing the winding 4| oi' the relay 35 from the power source C, which closes the relay armature 34 downwardly. Consequently, power from source B is applied through the contacts 29 of the air computing relay 25 through the lead'' to the switch contact 3l from which it passes through 'the leadl 50 and the relay winding 3| to continue the energization thereof and the retention ofthe switch contacts 413 to the right and hence continues to energize the winding |4a of the relay |4 to hold closed the gun port doors by means of the actuator |i.

(C) The airplane is in the air, -Jring.-The switch 39 is held closed by means of the spring 40, the firing switch 48 is closed, power from source B is applied through the switch and through the lead 43 to the heating elements 21 and 28, which are in parallel, to ground.' While the heating elements 2l and 28 are initially ener-l gized, the

closed contacts

29 and 30 open after a critical temperature is reached. Upon separatdelay.

ing, contacts 29 de-energize the relay winding 3| of relay |5, thereby Causing the 'contacts 44 to close to the left. Power from the source B is then able to flow through the switchv 48, the leadv 43, the right Vhand movable contact 49 of the relay I5 to the lead 43 to energize the winding I8 of the relayell to armature 22 to so interrupt the application of power from source A vialead 5| to the armature of the relay I4. The winding |4a of -relay le is now de-energized upon lthe de-energization of relay winding 3|. Power from source B is also applied for 0.10 second across the relay armaturev 2| to actuate mechanism to open the gun ports. The gun ports are held open by mechanism Il, as long as the switch 48 is held closed'and 25 seconds longer, due to the continued heating of heating elements 21 and 2B. After 0.10 second, the relay winding I8 opens the contacts 2| and 22 of the armature of relay The gun port doors remain open during ring due to mechanism 25 seconds after cessation of firing gun port closing mechanism 0 will operate provided critical temperature has not been reached. If critical temperature has been reached contact 29 is open, thereby delaying closing of gun port doors until a safe (non cook-off) temperature has been reached. After safe temperature has been reached due to cooling, contact 29v closes and doorswill close after normal l25second What we claim is:

1. A gun port door controlling mechanism including actuating means for opening and closing ra gun port door, Ia source of electric power, a rst circuit for energizing said actuating mechanism in `door opening direction, a gun-trigger-actuated switch for 'controlling said first circuit, a second circuit for energizing said actuating mech-anism in 'the door closing direc-tion, a thermal time delay relay for controlling said second circuit upon release of said trigger iactuated switch and heater means energized by said trigger-actuated-switch for varying the time -delay of said thermal relay in energizing said second circuit proportional to the time duration of closure `of said trigger-.actuated switch.

2. A control Idevice for controlling aircraft gun Iport door actuating mechanism comprising in combination with said actuating mechanism an electric circuit including a -source of Vpower for energizing the door actua-ting mechamsm in the opening direction, a trigger switch for controlling the energizing of said cir-cuit, a second circuit including a power source for energizing said door actuating mech-anism in the closing direction, a thermal time del-ay relay in said second circuit controlling the energization of said second circuit, said thermal relay having a pair Iof relatively movable circuit-controlling contacts, thermally responsive means for moving 'the contacts, :and heater means energized under the control of said trigger switch to cause said thermally `responsive means to move said contacts in one direction during closure oi the trigger switch, the cooling rate of said thermally responsive means being equivalent to the cooling rate of airplane type machine guns after firing so that said second circuit cannot be energized by said contacts until the rthermally responsive means has cooled to :a predetermined temperature.

3. In combination in a device ior opening and closing the doors of a gun compartment having one or more guns in said compartment, a door opening actuator, an electric circuit energizing said actuator, a slow break relay in said circuit,

,a door closing actuator, an elec-tric circuit energizing said actuator, a pai-r of thermal computing relays selectively included in said circuit, one relay having the same cooling rate as possessed by the gun it serves rwhen in flight in an airplane,

til

the other 'the same cooling rate :as the gun after it is red when in the same airplane on the ground, a switch common to both circuits, said switch being closed by the landing gear of the airplane when the airplane is on the ground, a relay for including the ground thermal computing relay in the circuits when said switch is closed and the :air thermal `computing relay in Ithe circuits when the switch is open, a trigger switch and a safety switch for the gun, said switches being included in both of the foregoing circuits to control the output of either circuit to the gun.

4. In a device for opening and closing the doors of a gun compartment in an -airplane in accordance with the .temperature fof a gun contained therein, said :airplane having a f-oldable landing gear, the combination which comprises a door opening actuator, an electric circuit including slow break relay means for operating said actuator by the opening of said relay, ya door closing actuator, an energizing circuit therefor, relay means included in said circuit Ito energize the circuit upon closing, a pair of -thermal computing relays selectively included in said circuit, one computing relay containing means to control by its cooling rate which is proportional to the cooling rate of the gun when the latter is not airborne the energizing circuit for said door closing actuator while the airplane is on the ground, the other `computing relay containing means to contro-l by its cooling rate which is proportional to the cooling rate of the gun when the latter is airborne the energizing circuit for said door closing actuator while the airplane is in the air, and switch means controlled by the landing gear of the airplane for including the first thermal relay in said circuit when the landing gear of said airplane is down and for including the second thermal relay in said circuit when said landing gear 1S up.

ROBERT R. BEACHLER, JR. JOHN M. OBERHOLTZER.

REFERENCES CITED The following references are of record in the rile of this patent:

` UNITED STATES PATENTS Number Name Date 1,720,723 Dodge July 16, 1929 2,057,384 Lamb Oct. 13, V1936