US2340006A - Airplane fire extinguishing apparatus and method - Google Patents

Description

Seam Ram P. G. M GREGOR Jan. 25, 1944.

AIRPLANE FIRE EXTINGUISHING APPARATUS AND METHOD Filed Aug. 2, 1940 3 Sheets-Sheet l lll INVEN TOR. PE TER GRAMM MagG/FEGM A TTORN E Y.

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Jan. 25, 1944. P. G. M GREGOR AIRPLANE FIRE EXTINGUISHING APPARATUS AND METHOD Filed Aug. 2, 1940 3 Sheets-Sheet 2 ATTORNEY.

005mb R0000 AIRPLANE FIRE EXTINGUISHING APPARATUS AND METHOD w m PM X TL E on Filed Aug. 2 1940 3 Sheets-Sheet 3 F IG.7.

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- INVENTOR. PETE (JIM/MM Man-68560 ATTORNEY.

EKsNGlllSriERS,

Patented Jan. 25, 1944 AIRPLANE FIRE EXTINGUISHING APPA- RATUS AND METHOD Peter Graham MacGregor, Pequannock, N. 1., assignor to Pyrene Manufacturing Company, Newark, N. J., a corporation of Delaware Application August 2, 1940, Serial No. 349,916

12 Claims. (01. 169-2) This invention relates to a method and apparatus for extinguishing fires in aircraft, and more particularly in and around the motors of airplanes.

A difficult and unique problem in the art of extinguishing fires is presented by fires that occur from time to time in airplanes while the airplanes are in the air. The forward motion of a plane through the air together with the air stream produced by the propeller or propellers creates a very rapidly moving stream of air through and around the motor of a plane, especially when air cooled internal combustion motors are employed. When a fire breaks out in such a motor, this high velocity air stream, which may be moving at a rate of 100 miles an hour or more relative to the plane, furthers the combustion of the burning material by the rapid supply of oxygen to it. A fire in an airplane motor, in fact, produces a condition quite similar to that existing in a blowtorch causing extremely rapid and high temperature combustion.

Such fires are sometimes caused by breaks in oil or gasoline feed lines but are more frequently caused by oil and/or gasoline escaping from a cracked cylinder in the motor. A fire of this type is intensively hot and rapidly damages other parts of the plane, making it extremely difficult and sometimes impossible to land the plane with any degree of security. Furthermore, if the plane is not landed properly with such a fire burning, the fire may spread very rapidly, even causing an explosion of the gasoline carried by the plane. The hazard therefore is very great and the problem of extinguishing such a fire while a plane is in flight cannot be solved by the usual fire extinguishing devices.

Furthermore, it is not practical to carry heavy fire fighting equipment in a plane for use in case of an emergency because the extra weight of such equipment seriously cuts down the efficiency and practical utility of the plane.

It is an object of my invention to provide a fixed, lightweight system that may be installed in a plane and operated in case of an emergency to extinguish a fire promptly, in any part of a plane in which such a fire may be expected to occur.

A further object of my invention is to provide a network of special spray nozzles located at strategic points in a plane for extinguishment of fires in combination with a quantity of fire extinguishing fluid that may be supplied quickly under pressure to the nozzles in case of an emergency.

A further object of my invention is to provide for extinguishing fires in aircraft motors while the aircraft is in flight without causing short circuits in electrical systems of said engines or otherwise damaging them. It will be apparent that the fire extinguishing method and apparatus of my invention are capable of extinguishing fires while an aircraft is on the ground, as well as while it is in flight.

Other objects and advantages of my invention will be apparent to those skilled in the art and will be explained in detail in conjunction with the description of certain embodiments of my invention illustrated in the accompanying drawings, in which- Figure 1 is a somewhat diagrammatic plan view of the central portion of a fuselage and two motors mounted in the wings of a plane equipped with a fire extinguishing system for the motors in accordance with my invention.

Figure 2 is a vertical section of one of these airplane motors on an enlarged scale taken approximately on the line 2-2 of Figure 1.

Figure 3 is a side elevation partly in section of such an airplane motor on a somewhat smaller scale than Figure 2 taken approximately on the line 33 of Figure 1.

Figure 4 is a side elevation partly in section of a spray nozzle that may be used according to my invention for extinguishing aircraft fires.

Figures 5 and 6 are vertical sections of this nozzle, taken on the lines 5-5 and 6-6, respectively, of Figure 4.

Figure '7 is a side elevation of an airplane motor broken away to show the auxiliary compartment equipped with an alternate arrangement of my improved extinguishing system.

Figure 8 is a vertical sectional view of such an engine, taken on the line 88 of Figure 7.

Figure 9 is a side elevation partly in section of a further embodiment of my invention showing my extinguishing system as applied to an airplane motor having a single row of cylinders.

-Figure 10 is a plan view on a large scale of one of the nozzles used in the motor shown in Figure 9.

Figure 11 is a horizontal section through approximately the center of a distributing manifold that may be used for a fire extinguishing system according to my invention.

In the drawings, numeral l 0 indicates the fuselage of an airplane having wings I I and a pair of motors indicated generally at H. mounted in the leading edges of the wings. While two such motors are shown, it is to be understood, of course,

that the invention is applicable to single motor planes or planes equipped with any desirable number of motors. The motors illustrated are 14 cylinder radial Pratt and Whitney Twin Wasp motors. Such motors are usually separated into two sections, (1) the cylinders l3 and the parts that must be located adjacent thereto, and (2) the instrument controls, carburetor, oil cooling and pumping system, and the like which are enclosed in a so-called auxiliary compartment l4 disposed rearwardly of the cylinders l3 and usually separated therefrom by a partition such as shown at IS. The cylinders 3 in the forward portion of the motor are usually covered by a removable cowl l6.

It is a feature of my invention to provide means for extinguishing fires in either the forward compartment of the engine enclosed within the cowl l6 or the auxiliary compartment 4, or in both places simultaneously. To this end, I provide immediately in front of the partition l and surrounding the crankcase ll of the motor as closely as possible, a distributing pipe |8 with a plurality of spray nozzles 20 and 2| extending forwardly from the distributor pipe Hi to points adjacent the base of the cylinders l3. If desired the distributor pipe may be welded to or cast as an integral part of the crankcase of the motor.

In an air-cooled motor provided with a double row of cylinders l3, such as shown in Figures 1, 2 and 3, the cylinders are usually staggered and separated from each other by curved baflle plates l9 to direct the air around the cylinders more efiiciently. In such a motor, the spray nozzles may consist of the short nozzles 2|! which extend to points just back of the second row of cylinders and adjacent the bases thereof with the spray nozzles directed radially outward, and the longer nozzles 2| which extend between each pair of the baffle plates I9 to points just back of the centers of the front row of cylinders and near the bases thereof.

In order to extinguish a fire in the auxiliary compartment l4, a second distributor pipe 22 of circular or other suitable shape may be installed just back of the partition l5. Since the full force of the air stream is not felt in the auxiliary compartment even when the plane is in the air, a much more static condition exists and the problem of extinguishing a fire at this point is somewhat simplified. Any suitable number of spray nozzles 23 of any satisfactory design may extend rearwardly from this distributor pipe 22. These nozzles 23 are preferably of different lengths with their spray openings directed radially inward to provide a relatively complete curtain of extinguisher fluid throughout the auxiliary compartment M.

The distributor pipe 22 may be connected by a pipe 24 extending rearwardly from the motor l2 and through the interior of the wing I I in which the motor is mounted to a bottle or other container 25 for the fire extinguishing fluid, preferably located in the pilots cabin or at some other convenient place in the fuselage of the plane. A short connecting pipe 24a may be used to join the two distributor pipes l8 and 22 for simultaneous operation of the nozzles 20, 2| and 23. The container 25 which holds the fire extinguishing fluid should be of sufficient size and strength to hold this fluid under considerable pressure. The flow of the fluid from the container 25 to the distributor pipes 22 and I8 is controlled by a suitable valve 26 in the pipe 24 near the container 25,

preferably located conveniently for manual operation.

If desired, suitable fire indicator devices may be provided, consisting essentially of thermo couples 21 and 28 in the forward and auxiliary compartments of each motor and connected by suitable wires 29 to a signal light 30 in the pilots cabin. The wires 29 may be supplied with current from any suitable source (not shown) such as batteries carried in the plane. The operation of the valves 26 may be readily made automatic to open the proper valve 26 as soon as a fire breaks out in either one of the motors. To accomplish this operation, the wires 29 may be connected in series with a solenoid or other suitable means 3| for opening the Valve 26 automatically when the indicator circuit is energize by either one of the thermo- couples 21 or 28 in the motor compartments.

Under most condtions, however, it will be satisfactory and may even be preferable to operate the fire indicators and fire extinguishing systems independently and to open the valve 26 releasing the fire extinguishing fluid by hand when the indicator device shows the presence of a fire or such a fire is discovered by some other means.

A particularly satisfactory spray nozzle for use in accordance with my invention is illustrated in Figures 4, 5 and 6, and consists of a tube 32 fitted with a cap 33 fixed in position on its end in any suitable manner as by threads, welding or other suitable means. A semi-circular transverse slit 34 is cut through the pipe 32 and the side of the cap 33 at a point some distance from the forward end of the cap 33 and extending in a plane at a right angle to the tube 32. The forward end of the cap 33 is provided with an internal opening 35 of substantially smaller diameter than the bore of the pipe 32, and another semi-circular transverse slit or opening 36 is cut in the forward end of the cap in an inclined plane as seen in Figure 4. The slits or openings 34 and 36 extend only part way around the cap 33 and both may be made of substantially semi-circular shape extending around the same of the surface of the cap 33. It will be apparent, of course, that the slits 34 and 36 do not have to be exactly semicircular but extend more or less than 180 around the surface of the cap 33.

In the operation of this system illustrated in Figures 1 to 6, inclusive, a fire in either the forward or auxiliary compartment of one of the motors I2 is detected by means of one of the thermo- couples 21 or 28 and indicated by one of the red lights 30, or the fire may be discovered by other means. When a fire is discovered, the proper valve 26 is opened (manually or automatically) and fire extinguishing fluid held in one of the containers 25 under pressure is forced through the pipe 24 connected thereto to the distributor pipe 22 and I8. From these distributing rings, the fire extinguishing fluid is forced out through the spray nozzles 23, 20 and 2|.

The nozzles in the auxiliary compartment l4 may be constructed as illustrated in Figure 4, or any other suitable types of sprays may be used. In any case, spray nozzles 23 direct a number of staggered jets of extinguishing fluid radially inward from the outer edge of the auxiliary compartment, quickly extinguishing any fire that may be burning therein by rendering the supply of oxygen in the compartment insufficient to support combustion.

The spray nozzles 20 and 2| are preferably of the construction shown in Figure 4 and are arranged to throw sprays of the fire extinguishing fluid radially outward from points just back of and near the bases of the motor cylinders. This spray of extinguisher fluid consists of sheets of the fluid thrown at a slight angle in a forward direction through the slits 36 and sheets of the fluid thrown at a somewhat higher through the rear. slits 34 ina direction at right angles-toair stream flowing around the motor cylinders. These double sheet sprays are subject to the efiect of the rapidly moving air stream which tends to bend backward the forwardly inclined sheets of fluid from the slits 36. The two sheets of fluid from each nozzle thus serve to reinforce each other and provide a much greater effective radius from the spray nozzle. In this manner, the nozzles operated simultaneously are capable of throwing outwardly from the crankcase of the motor a curtain of extinguisher fluid for a considerable distance.

By placing the spray noozles and 2| just in back ofthe bases of the motor cylinders l3, the flame from any burning oil or gasoline coming around or over the cylinders or from a crack in the side wall thereof is quickly extinguished. Since the air stream is moving towards the rear of the cylinders, it has been found that the high temperature combustion takes place near the rear edge of the cylinder. A surprising feature of my invention is that the location of the spray nozzles to deliver extinguisher fluid to the rear portions of the cylinders is far more effective than placing these nozzles near the front portions of the cylinders. In a high velocity air stream, the extinguisher fluid is dissipated or dispersed too much to be effective if the nozzles are placed too far forward, but the delivery of a concentrated spray of fluid to the rear portions of the cylinders cuts off the flame quickly and completely without any back flash and without requiring the use of large quantities of fluid.

The fire extinguishing system described works most efficiently with a suitable halogenated hydrocarbon as the fire extinguishing fluid. Carbon tetrachloride is readily available in large quantities and provides an excellent fire extinguishing medium. Containers may be partially filled with this liquid and pumped up to a suitable pressure. This pressure should be sufficient to allow all or most of the-liquid to be expelled through the spray nozzles before the pressure is completely lost.

For example, it has been found that with a fire extinguishing system using 14 double nozzles of the type shown in Figures 4 to 6, and, located around the motor cylinders as shown in Figures 1, 2 and 3, a gallon or even less carbon tetrachloride held in the container 25 under a pressure of 150 lbs. per square inch is adequate when released by opening the valve 26 to extinguish any type offire that may occur in or around the motor cylinders under conditions such as exist during flight of the plane. After the discharge of a gallon of the liquid, the pressure in the container will have dropped to about 40 lbs. per square inch,but such a pressure is still suflicient to produce the full radius of .liquid expelled through the nozzles. 7

Lower initial pressures in the containers 25 may be employed, particularly if smaller quantities of extinguisher fluid are used. It will be understood that theexact volume of fluid and the initial pressure needed will depend upon a number of factors including the number of nozzles, their size, the size of the distributing velocity Qtiidlliil some pipes, etc. Other halogenated hydrocarbons, such as methyl bromide or trichlorethylene, or other volatile halogenated hydrocarbons having fire extinguishing properties, or combinations of such halogenated hydrocarbons may be used instead of carbon tetrachloride, as will be understood by those skilled in the art.

Another embodiment of a spray nozzle arrangement that may be used in the auxiliary compartment of an airplane motor to protect the exhaust pipes and oil cooling system of the motor as well as the compartment itself is illustrated in Figures 7 and 8. In this arrangement, the distributor pipe 18 for the cylinder nozzles may be disposed as previously described within the cowl l6 around the crank case of the motor, and the partition I 5 divides the cylinders from the rearwardly disposed auxiliary compartment l4.

The lower portion of this auxiliary compartment 4 may be provided with a depending section comprising a housing 31 with a forwardly extending air inlet pipe 38 and a centrally disposed grille or radiator 39 inside the housing 31 through which oil for the motor is circulated for cooling. At the sides of the compartment l4, enlargements 40 in the walls of the compartment are provided to surround two exhaust manifolds extending rearwardly from and connected to the exhausts of the motor cylinders.

Disposed in the shape of two complementary semi-circles inside the compartment M are the two extinguisher fluid distributor pipes 4| and 42. The ends of these pipes, as indicated in Figure '7, are curved towards each other, so that each pipe lies in a curved plane. A suitable number of short spray nozzles 43 are connected at intervals along the length of these distributor pipes 4| and 42 to provide spaced jets of extinguisher fluid projected radially inwardly throughout the entire Volume of the auxiliary compartment l4. One end of the distributing pipe 4| has a curved extension 44 in one of the sections 40 of the compartment wall surrounding one of the exhaust pipes. A similar curved extension 45 is formed a on one end of the other distributor pipe 42 and surrounds the other exhaust pipe within the other compartment wall section 40.

Suitable slits 46 may be provided in theseextensions 44 and 45 of the pipes 4| and 42 to form a solid spray of extinguisher fluid around the exhaust pipes. Two downwardly directed sprays 41 are provided near the lower portion of the distributor pipe 42 for directing sprays of extinguisher fluid downwardly on each side of the grille or radiator 3.9 within the housing section 31.

The extinguisher fluid may be supplied to these distributor pipes and nozzles under pressure in the manner previously described, or by means of pressure stored either in the liquid compartment or in another compartment connected therewith, through the pipe 48 extending from a suitable container to the distributor pipe 4|. The connecting length of pipe 49 carries the fluid to'the forward distributor ring I8 for the motor cylinders, and another section of pipe 50 carries the fluid from the-distributor ring l8 to the second auxiliary compartment distributor pipe 42.

Referring now to Figures 9 and 10 which show an arrangement particularly adapted for supplying extinguisher fluid to an air-cooled radial motor having a singlerow of cylinders, no specific arrangement for supplying extinguisher fluid to the auxiliary compartment is shown, it being understood that any suitable form such as those previously described or other suitable arrangements of nozzles may be used. In this case, the motor cylinders 5! are surrounded by a suitable cowhng 52 and are provided around and preferably as close as possible to the crank-case of the motor with a circular distributing pipe 53 which receives extinguisher fluid under pressure from a suitable container through the pipe 54. Spray nozzles 55 project forwardly from the distributor ring 53 and lie against or close to the crankcase between the motor cylinders 5|.

Nozzles that may be employed for this embodiment are illustrated in more detail in Figure 10, and are provided with two semi-circular slits 56 and 51 similar to the slits 36 and 34, respectively, in the spray nozzles shown in Figure 4. These slits are capable of projecting approximately semi-circular discs or sheets of fire extinguisher fluid supplied to the slits through the central opening 58 in the main tube 59 of the spray nozzle. what to the plane of the slit 51 in a manner similar to the inclination of the slit 36 in the spray nozzle shown in Figure 4. Between the slits 56 and 51 is a further slit 60 made by two intersecting cuts at approximately right angles to each other in the tubular head 59a of the nozzle, thus providing an X-shaped opening through which extinguisher fluid may be projected. The slits 56, 60 and 51 are all designed to project the extinguisher fluid in the same general direction, and the spray nozzles 55 are preferably disposed so as to project this fluid in a general direction radially outward from the crankcase of the motor.

The nozzles are preferably arranged so that the cross-shaped slits 66 are disposed approximately on the center line of the motor cylinders 5| with the inclined slits 56 disposed a substantial distance ahead of the center line of the cylinders. With this arrangement the spray nozzles 55 in extinguishing a fire project a triple curtain of extinguisher fluid radially outward from points between the motor cylinders and near the bases thereof. The force of the Wind stream tends to sweep this curtain of extinguisher fluid rearwardly, so that the fluid from two adjacent spray nozzles 55 strikes the motor cylinder between them along its rear edge, thus effectively cutting off any flame streaming from the back of the cylinder.

The embodiments of my invention described above make no special provision for distributing or carrying the fire extinguisher fluid from the container to the various spray nozzles without any time lag, and such a provision is not essen-- tial. I have found, however, that it may be desirable to use a distributing reservoir or some other suitable means for distributing the fluid uniformly and under uniform pressure to the various spray nozzles if equalization in the force of the sprays is desired. This also avoids the necessity of carrying the extinguisher fluid in the container 25 under an excessively high pressure or of using too great an excess of fluid.

One such distributing means is shown in Figure l1 and comprises a pipe 6| having a suitable threaded flange member 62 secured thereto through which the fluid is received under pressure from the container 25. A perforated cup shaped head piece 63 may be screwed on to the flange 62 holding a suitable filter screen 64 in place between these two parts, if desired. This provides between the head piece 63 and the flange member 62 a reservoir 65 for the extinguisher fluid supplied thereto under pressure.

A number of separate distributor pipes 66, five The slit 56 is preferably inclined somei of which are illustrated, may be provided communicating with the reservoir 65. These pipes 66 may each be connected to one or more of the spray nozzles provided for the motor cylinders. Additional distributor pipes 61 of the same or somewhat larger size may be provided leading fromthe reservoir 65 for distributing the extinguisher fluid under pressure to the spray nozzles in the auxiliary compartment. Usually two of these auxiliary distributor pipes 61 will be suflicient inasmuch as the auxiliary compartment of the motor is usually substantially completely enclosed and the high pressure jets of extinguisher fluid are not as essential at this point as they are around the motor cylinders and other parts exposed to the rapidly moving air stream.

If individual supply pipes 66 are used for each motor nozzle or pair of nozzles, the distributor pipes such as shown 53 and I8 will not, of course, be needed. On the other hand, a reasonably good distribution of the fluid may be obtained if the fluid is delivered to four or five spaced points around one of distributor pipes 53 or l8 through individual tubes 66 from the reservoir 65.

The terms and expressions which I have employed are used as terms of description and not of limitation, and I have no intention, in the use of such terms and expressions, of excluding any equivalents of the features shown and described or portions thereof, but recognize that various modifications are possible within the scope of the invention claimed.

lclaim:

1. Apparatus for extinguishing a fire in an aircraft motor comprising a plurality of nozzle means fixed to said aircraft for delivering jets of fire extinguishing fluid in sheet form toward the rear of portions of said motor exposed to fire, and means for supplying fire extinguishing fluid under pressure to said nozzle means.

2. Apparatus for extinguishing a fire in a portion of an aircraft motor exposed to a rapidly moving air stream comprising a, nozzle for delivering to the rear of said portion at approximately right angles to the direction of said air stream a plurality of thin sheets of fire extinguisher fluid, and means for supplying said fluid to said nozzle under pressure.

3. Apparatus for extinguishing a fire in an aircraft motor comprising a plurality of nozzles positioned to deliver thin sheet-like jets of fire extinguishing fluid to the rear portions of the cylinders of said motor, and means connected to said nozzles for supplying fire extinguishing fluid thereto under pressure.

4. A system for extinguishing a fire in an aircraft motor comprising a container for holding fire extinguishing fluid under pressure, a plurality of spray nozzles for projecting thin sheetlike jets of said fluid in a direction transverse to the path of movement of said aircraft, said nozzles being mounted in said motor adjacent the rear portions of the cylinders thereof, conduit means connecting said container to said nozzles, and valve means for controlling the flow of fluid from said container through said conduit means to said nozzles.

5. An aircraft fire extinguishing system for an aircraft motor having an auxiliary compartment and internal combustion cylinders separate therefrom comprising a plurality of nozzles for delivering sheet-like jets of fire extinguishing fluid to the rear portions of said cylinders, a plurality of nozzles for delivering jets of said fluid to the interior of said compartment, and

i691 HRE EXTlNQUiSHERS,

means for supplying said fluid under pressure substantially smultaneously to both groups of said nozzles.

6. Apparatus for extinguishing a fire in an air cooled aircraft motor comprising means for delivering sheet-like jets of fire extinguishing fluid to the rear portions of the cylinders of said motor, said means being located adjacent the crankcase of said motor and means for supplying said fluid under pressure to said means.

7. Apparatus for extinguishing a flre in an aircraft motor comprising a plurality of nozzles for projecting sheet-like jets of fire extinguishing fluid towards the rear of exposed portions of said motor, and means for supplying said fluid under pressure to said nozzles, said nozzles having relatively long and narrow openings arranged side by side to project simultaneously in substantially the same direction two separate sheets of fluid.

8. A process of extinguishing a fire in an air cooled internal combustion motor of an aircraft while said aircraft is moving comprising directing against the rear portions of cylinders of said motor jets of fire extinguishing fluid in the shape of sheets, said jets being projected so that said sheets are more or less at right angles to the general direction of the air stream through said motor.

9. A process of extinguishing a fire in an aircraft motor having cylinders and an auxiliary compartment separate therefrom comprising delivering sheet-like jets of fire extinguishing fluid against the rear portions of said cylinders, and simultaneously projecting a plurality of jets of said fluid into said compartment.

Search new 10. Apparatus for extinguishing an aircraft motor fire comprising a plurality of nozzles disposed to project sheet-like jets of fire extine guishing fluid toward rearward portions of the cylinders of said motor, and means for supplying said fluid under pressure to said nozzles, at least some of said nozzles comprising tubular members extending longitudinally of the aircraft and having separate elongated openings for projecting a plurality of sheets of fluid simultaneously in the same general direction.

11. Apparatus for extinguishing an aircraft motor fire comprising a plurality of nozzles disposed to project sheet-like'jets of fire extinguishing .fluid toward rearward portions of the cylinders of said motors with the longitudinal axes of said jets transverse to the longitudinal axis of the aircraft, and means for supplying said fluid under pressure to said nozzles, at, least some of said nozzles comprising tubular members having a pair of elongated openings for projecting sheet-like jets in the same general direction with the plane of the jet from one of said openings inclined at a small acute angle away from the plane of the jet from the other of said openings.

12. Apparatus for extinguishing a fire in a radial motor of an aircraft which comprises a plurality of nozzle means for delivering radially outward thin sheet-like jets of fire extinguishing fluid, said nozzle means being located near the rear of the bases of cylinders of said motor, and means for supplying said fluid to said nozzles under pressure.

PETER GRAHAM MACGREGQR.

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