US1626921A - Safety attachment for aircraft - Google Patents

Description

3 1927. T. DOUGLAS SAFETY ATTACHMENT FOR AIRCRAFT Filed Jan. 24. 1919 2 Sheets-Sheet 1 INVENTOR Theodore Doqg BY WM ATTORNEY May 3,1927. 1,626,921

"r. DOUGLAS SAFETY ATTACHMENT FOR AIRCRAFT Filed Jan. 24. 1919 2 Sheets-Sheet 2 ads Mon 275420 We floaylas.

Patented May 3, 1927. p p

UNITED STATES PATENT OFFICE.

THEODORE DOUGLAS, OF SCARBORO, NEW YORK, ASSIGNOR TO DUPLEX ENGINE GOVERNOR COMPANY, INC, OF BROOKLYN, NEW YORK, A CORPORATION OF NEW YORK.

SAFETY ATTACHMENT FOR AIRCRAFT.

Application filed January 24, 1919. Serial No. 272,958.

The invention herein set forth relates to an attachment for aircraftg'and aims to provide an instrument which can be combined with the power system embracing the engine of the airship in such a way that, whenever a shock involving the engine occurs. the operation of the latter is interrupted at once by the automatic suspending of the operation of the ignition system supplying electrical current to the cylinders of the engine to produce combustion of the fuel therein.

My invention is designed for airships with one or more engines, and is capable of acting in case of emergency, to affect and ,control the ignition system by either open-circuiting or short-circuiting the same, thereby afiording the attainment of the desired end.

An object of my invention is to provide an attachment which will be simple in construction and capable of being easily applied and connected in operative relation so that it will instantly and infallibly take effect under predetermined conditions to avert serious consequences before the aviator can take measures by hand to insure his own safety and the safety of his machine.

It very ofteri happens when an aviator is making a flight that a propeller blade breaks or something else happens; making the engine immediately become unbalanced and wrench itself loose from its anchorage. Frequently in such cases the gasoline line is broken, and fire has been known to start as a consequence of the continued sparking in the engine cylinders and the flaming exhaust into the atmosphere before the aviator has time to manipulate the main switch of the ignition circuit; even when such switch is easily within his reach. Under such circumstances the engine may not only tear itself from its fastenings, but even go overboard before the aviator can fully realize what has come to pass; and when fire due to the escape of gasoline commences, the end ofboth flier and flying machine may follow.

Such breakag-es are infrequent under ordinary conditions, but likely to happen, from gunfire and accidentally, in war. In an 0 aerial engagement, the objective is to put either the hostile flier or his machine out of commission; therefore the pilot and the machine carrying him are the important targets. Now, when an aviator is in action he machine, he necessarily sacrifices altitude;

which is priceless and generally determines whether he can get back over the enemys barrage into his own territory.

My invention eliminates the danger from accidents such as I have just outlined by mechanism which is quite simple, involving relatively few parts and comprising no eon struction which is bulky, complicated or expensive; and which can be mounted upon an airship so that it will instantly respond to an abnormal vibration or other bodily movement of the engine driving the same, in order to cut off the flow of ignition current to the spark plugs and cause the engine to stop developing power. In this way, in case a propeller blade should break, or something else should happen to unbalance the engine, the danger of the latter tearing itself loose and causing a destructive fire is fully obviated. Hence the instrument does not in any way interfere with the airship but on the contrary is of great utility; making the pilot free for his fight with the enemy and enabling him to sail about and maneuver aloft in complete confidence.

Other objects and advantages of my invention will more clearly appear from the following description, taken in connection with the accompanyine drawings forming a part of the same; and the characteristics of my invention will be precisely defined in the appended claims. This disclosure, however, is explanatory only, and I reserve the right to adopt embodiments of my invention other than what is actually shown herein to the full extent indicated by the general meanings of the terms in which the claims are expressed.

On the drawings Figures 1 and 2 are top and bottom views of the casing of an instrument according to my invention; 7

Figure 3 is a view of said casing and con tents, without the cover;

Figure 4 is asection on line 4.4, Figure 3;

Figure 5 is a bottom plan of the cover of i this instrument;

Figure 6 shows diagrammatically circuit connections therefor; illustrating the manner in which the invention is'comhined with the ignition system;

Figures 7, 8 and 9 are top. bottom and end views of a switch for the instrument;

Figures 10 and 11 show top and bottom views of the casing of a modified form of instrument Figure 12 is a view thereof, similar to Figure 3;

Figure 13 is a section through Figure 12 similar to Figure 4;

Figure 14 is a bottom of this modification; and

Figure 15 shows a diagram of the circuits for same.

The invention described hereinafter is an improvement upon a similar invention set forth in my copending application, Serial Number 209,130, filed December 27, 1917.

The same numerals identify the same parts throughout.

Referring to the first two figures on the drawings, I show one form of my safety attachment for the power system of an airship as a Whole at 8. The arrangement of the parts of this attachment is such that, as I shall set forth fully hereinafter, the attachment will automatically cut off the ignition current by open-circuiting the ignition system and it is adapted to be operated by any abnormal bodily movement of the engine, as when there is an unbalanced condition resulting from a broken propeller blade. In that event the torque of the engine, which would be normally divided by the blades and thus produce a balanced load, is then no longer properly divided; producing a badly unbalanced load, and jerking or pushing the engine from side to side as the propeller revolves. Under such circumstances a tractor plane is liable to go into a dive; a pusher plane into a tail stall; and either is apt to pass next into a tail-spin, and the engine may or may not go overboard entirely. If this side pressure does become so great that the engine is broken from its foundation and thrown out of the airship, the center of gravity of the machine is upset, completely destroying its equilibrium, and effecting other and more serious damage. The attachment 8 produces a suspension of the operation of the ignition system to stop the engine chiefly through the instrumentality of an element such as a pivotally mounted bar 11, comprised in the attachment 8, and housed in a casing 12. See Figure 3. This bar has sufiicient mass, and it is supported upon its pivot 13 in the easing 12, so that it can move or swing or us cillate, like a pendulum, in a direction that extends across or transversely of the longi tudinal axis of the engine; that is the bar should preferably swing parallel to the plan of the cover plane of the propeller. I may secure the attachment 8 to any part of the aeroplane so related to the engine that any transverse jar will instantly be transmitted to the bar 11 hence I can mount the attachment either upon some part of the engine framework directly, or upon a part of the aeroplane or other airship rigid with it. such as the instrument board in the pit of the fuselage; or near enough to it to be subject to its vibration, such as one of the engine hearers when in the wings. Preferably the casing 12 and bar 11 are both in vertical position, and the bar, to stop the engine, swings in a direction transverse to the crankshaft thereof. I may also mountthe casing 12 so that it will be horizontal and the bar 11 will normally lie parallel to the crankshaft. However, the car 11 will still be in position to swing in a direction transverse to the crankshaft, and the attachment can therefore perform is function when needed quite as easily as in the first instance, to respond to a transverse shock from the engine as a result of its unbalanced torque reaction.

The casing 12 and parts borne thereby are illustrated, particularly in Figures 3 and 4. It comprises sides and ends; to which is secured a bottom and a removable cover 21. The sides, ends, bottom and cover of the casing are preferably of some insulating substance, such as fibre or rubber. To the bottom 20, near the upper end of the casing is fixed an inverted metal yoke 22 in which is carried the pivot pin 13 whereon the bar 11 is hung. As will appear presently, whenever the bar or element 11 is constrained to swing sidewise, it acts very promptly in the required manner.

On the outside of bottom 20 of the casing 12 are located four electrical terminals orbinding posts 25; extending into the casing and each joined to a conductor 73. These binding posts enable the instrument to be connected into the ignition system and the conductors lead to the parts in the casing that are embraced in the circuit or circuits of same.

At a distance from the pivot 13 to one side of the bar 11 is a compression spring 42". Thefree end of the bar 11 carries a pin or handle 45 which projects through a slot in the adjacent end of the casing; and to this pin are secured two other springs 46, one at each side. The spring 42 and the springs 46 separately constitute means for damping the oscillations of the bar, and prevent it from functioning under ordinary conditions. These springs, especially the springs 46, also serve to restore the bar 11 to neutral position after movement of same. I oin the opposite ends of the springs 46 to adjustable nuts 50, each of which is movable in the bore of a boss 49. The bosses 49 are at opposite sides of the casing 12. By manipuletting the nuts the bar 11 can be moved to exact central position; audit will so remain until occasion requires it to swing away from central position. The springs 46, with the nuts 50* thus serve also as means for adjusting the bar 11 in addition to damping it, and by means of the nuts 50', the tension of the springs 46 can be changed as desired.

The spring 42 is carried at one side of the casing near the springs 46, upon a. screw 67 in a threaded bearing 68, in the side wall of the casing. This bearing is situated in a threaded boss 69, closed by a nut 70, in the bore 71 of this boss. A kerf in the screw 67 permits turning the screw from the outside of the casing by a tool when the nut is removed.

Each spring 46 is attached to a plug 72 projecting through the adjacent nut 50, which engages threads inside the boss 49. These nuts receive heads on the plugs 72 and the nuts can be shaped in any suitable way to be turned by a tool or other device, from without the casingand regulate the springs 46. Closures for the outer ends of the bosses 49 may be provided.

At the right, inside the casing, are two conductors 73, each leading to an element 23 on the bottom 20, mounting a pivoted element 74, extending over bar 11 and carrying a, shoulder 36 to engage a dog 75 on a rotatable spindle 76 at the left. Each spindle 76 has an arm 77, secured to a tension-spring 78 anchored in a recess in the bottom of casing. 12. These springs force the dogs 75 against the shoulders 36. Other elements 23 on the bottom 20 mount the spindle 76 and are connected to similar conductors 73 in the casing 12. All conductors 7 3 are joined to binding posts 25 on the back of the casing. Each element 74 has a cam face 79 and the bar 11 carries round-ended steel screws 80 to engage the cam faces 79.

A transverse shock causes the bar 11 to move the elements 74 upward, releasing the dogs 75. To free these dogs 75 simultaneously I place the screw 80 which is nearer to the pivot 13, so as to be adjacent the left side of the bar, and the other screw 80 at the right side. The bar is recessed at 81 adjacent the latter screw to give the adjacent cam face 79 sufiicient clearance till this other screw strikes it.

This instrument is for engines havingtwo distributors and is connected so that" each element 74 is joined in series with the main circuits of the ignition system. Figure 6. In this view two electrical generators, such as batteries or magnetos are shown at 82. Each is in series through suitable conductors with one of the elements or triggers 74; and from the attachment 8 the current from those generators passes to suitable translating devices 83, which may rep resent distributers. These distributers supply high tension current to the spark plugs of the engine by turns, the current from each generator being stepped up before it passes through the-distributer by suitable means, such as a transformer, or induction coil. The engine will have two sets of igniters, one set supplied from one generator and distributer and the other set by the remaining distributer and generator. Hence each cylinder of the engine will have two spark plugs and both sets of igniters may be used together, or only 'one at a time, with one of the generators and distributers, may be in service; the other set, with the remaining generator and distributer, being kept in re serve, as an auxiliary or relay, to be thrown in if the first set fails or ceases to Work properly. A shock will open the circuits of both generators and distributors at once.

The bar 11 is insulated, and elements 23 and 74, the dogs 75 and the spindles 76 conductive. I

My invention is of course useful on pusher planes as well as tractor planes; and ondirigible balloons; because when a propel ler on a balloon breaks, fragments may puncture the gas bag and liberate the inflammable contents.

When an accident happens the flier hardly ever has time to do anything to save him self, even if he remains calm and uninjured. With the attachment 8, ignition is automatically terminated within a fraction of a revolution of a high-powered. engine; and if gasoline is spilled, fire does not ensue.

Casing 12 may also be placed parallel to the wings if the bar 11 is arranged to swing transversely of the engine.

The force of the springs on each side of the bar 11 is of course adjusted to make the attachment 8 inoperative Within the limits of the safe operation of the engine; causing the pendulum bar to remain neutral until that limit is exceeded.

It sometimes happens too that when an aviator is making a flight an accident may happen in some other manner than by the breaking of a propeller blade, and may cause a shock to the engine that is more or less parallel to the axis of the crankshaft instead of transverse to the same. Such a situation may result from a collision. If it is desired to guard against such athing, the attachment 8 can be mounted so that the casing 12 willhave its top 21 and bottom 20 parallel with the crankshaft of the engine. and with the bar in vertical or horizontal position, but transverse to the crankshaft of the same. With this arrangement a collision producing a substantially longitudinal shock will cause the bar to swing in a plane that is more or less parallel with the engine mishap of both kinds; that is, anything that might produce a transverse shock to the englue or a longitudinal shock also; I may use two of my attachments 8 with the same engine, by mounting one so that the bar will be able to swing in a direction transverse to the crankshaft and the other so that the bar can swing in a direction that is more or less parallel with the crankshaft. The two instruments may both be arran ed, for example, so as to suspend the ignition, whichever one takes effect, by connecting the two instruments in series with each other; that is to say, simply by adding another instru ment to the one shown in Figure 6, and connectingit in circuit with the generators, etc., in the same way. Then in case of a collision, whichever of the two instruments allows its pendulum bar to swing in a direction parallel to the crankshaft will cause the opencircuiting of the ignition system; and in case a shock occurs transversely of the engine, the other one will produce the required effect. With two attachments on an aeroplane, the ignition can be interrupted in case of an accident that is caused by practically any shock to the aeroplane substantially parallel to the plane of the wings, whether longitudinal or transverse, or even in a diagonal direction; although the mode of operation will be best and surest of course when the shock is either directly transverse or directly along the length of the engine.

The spindles 76 also each have an arm 84, beneath a projection 85 on a plunger 38 in the cover 21. After the dogs are released, the pressing of this plunger, through the arms 84, turns the spindles 76 to reengage the dogs with the shoulders 36. A spring 10 engages the head of the-plunger and the cover to force the plunger normally outward with respect to the casing.

The spindles 76 also have arms 86, one on each spindle, which press against slide members 87; said members being in grooves, not shown, on the inner face of the cover 21, be neath openings 88 therein; and engaged by springs 89 upon projections carried by strips 90. See Figures 4 and 5. When the elements 74 hold the dogs 75, the arms 86 force the members 87 to keep cross-marks thereon out of registry with openings 88. These marks come into registry ,with the openings 88, when the elements 74 release the dogs. By luminous paint these marks may be made visible at night and they tell whether or not the instrument is ready. The strips 90 retain the members 87 in place on the inner face of the cover and have slots to receive downturned ends of the members 87. abutting the springs 89. (Figure 5.) The projections on these strips engaging the springs 89 are at the opposite ends of the slots, and the downturned ends of the members 87 can move freely in these slots, as will be understood.

In Figure 1, the cross marks appear. But with the elements 74 and dogs 75 as in Figure 4, the marks will not be visible.

Figures 7, 8 and 9 show a switch comprising insulation 91 carrying two conductive members 92, between which are two pairs of spring contacts 93, one pair at each side.

The contacts at the left are joined to binding posts'25 at the left, by strips and screws passing through the insulation 91. (Flgure 8.) The contacts at the right are disconnected. Bearing members 92 are joined by screws and strips on the bottom of the insulation 91 to the binding posts 25 at the right; and support a handle 94 of insulation, carrying separated metallic strips 95 having trunnions 96, to pivot it. This switch is to be in multiple with the instrument 8 (Figure 6), the two upper posts being connected in the line of one generator 82, and the remaining posts in the line of the other. With handle 94 to the right (Figure 7) the two upper posts are bridged, likewise the two lower posts, and the instrument is shunted out. lVhen thrown to the left the switch moves the metallic strips 95 upon the contact springs 98, at the right, and the binding posts will be disconnected, throwing the instrument in. Stops 97 on the. members 92, limit the throw of the switch. This switch in some cases can be mounted directly on the cover 21. 1

Figures 10 to 15 inclusive illustrate a modification having a single catch 34 over the bar 11, engaging a single dog 7 5 on a single spindle 76 in the casing 12. On the back of the casing are right and left binding posts 25, connected to conductors 73 on the inside of the casing. One of these conductors extends to and is electrically con nected with a contact element 98, secured to the bottom of the casing 12, and having a projection 99, hearing against the spindle 76. The other conductor 73 leads to a contact element 100, fast under the element 23 which supports the spindle 70. This element has a projection 101 bent towards the dog 75. Below this projection is another contact element 102 to be grounded through a third conductor 73. lVhenever the dog 75 is liberated it presses the projection 101 upon the terminal 102, grounding both conductors 73, connected to the right and left posts 25.

The terminal 102 joined to an element 103 on the bottom of the casing in circuit with the element 104 carried by the cover 21. A switch on the outer face of the cover 21 comprises springs 93, the left spring being connected to the element 10 i and the other spring at the right being dead. See Figures 10 and 13. The handle 94, of insulation, has a metal inset 95 to engage the springs 93. A pivot or trunnion on the handle engages the member 92 and connects electrically with the metal inset 95. One member 92 is insulated; the other is in circuit through a metal strip 105 on the cover 21 with the third conductor 73, and third binding post 25 on the back of the bottom of the casing. When the switch is thrown to the right, the elements 104 and 105 will be connected, and disconnected when the switch is thrown to the left. Figure 15 shows the diagram of circuits. This instrument is for engines with two ignition circuits, supplied with ignition current from two magnetos 3; and grounds both magnetos through the post 25 One magneto serves for one circuit and the other for the remaining circuit and as many spark plugs will be connected to each magneto as there are cylinders to the engine associated therewith. The spark plugs may be utilized as before with both magnetos, both circuit and all the plugs in service at once; or only'one ignition circuit with one magneto and one set of plugs may be active, the other circuit with its plugs and magneto being in reserve. These spark plugs are indicated diagrammatically at 2. This instrument too may be made up with the switch separate.

Both the above-described instruments have springs 41 engaging parts 74 and 34", and surrounding stems passing through holesin these parts and receiving the adjusting nuts 107 to regulate the springs.

Both instruments can be employed on not only airships having one engine with two ignition circuits, but also twin-engined machines; with two propellers; as an accident to one engine would cause the other to swing the plane around into a dive and perhaps into a tail spin. This usefulness for twinengined machines is especially the case with the instrument shown in Figures 1 to 5 inclusive. On a twin-engined machine there will be two such instruments, one associated with each engine; and the wiring must be such that each instrument must be included in the ignition circuit or circuits of both engines. Then the breaking of a propeller driven by either engine will result in actuating the bar 11 of the instrument associated therewith; and the ignition circuits of both that engine and its mate will be afiected instantly. Hence both engines will be immediatelymade to cease developing power simultaneously. A switch like that shown in Figures 7, 8 and 9 will be arranged to shunt out both instruments when desired. After a mishap, the pilot can cut out the two instruments-and land with dead engines, or switch on his undamaged engine and continue with it at reduced speed.

When the cover in Figure 14 is applied, the element 103 may be connected to element 104 and the element 105 to the third conductor 7 3 by metal screws passing through metallic bosses in the cover into metallic sockets in the bottom casing. Additional screws, bosses and sockets may be employed to hold the cover on the casing, both in this modification and the preceding. (Figure 1 above openings 88 and Figure 14 at the ends of the switch.)

The casing for both instruments is shown of insulation, but may be of metal with an insulating cover, and a bottom insulated from the sides. The instrument last shown in Figures 10 to 14 inclusive may also be used to guard against transverse shock or collision, or both. In view. of a propeller blade breaking, the bar 11 will be arranged as before to swing transversely of the airship; and longitudinally in case of a collision. To guard against both kinds of accident two instruments shown in Figures 10 to 14 inclusive are put in parallel with each other and with the ignition circuit, one being mounted to let the bar swing transversely and the other longitudinally of the engine, as set forth above.

Springs 46 and 42 prevent operation of the bar 11 to suspend ignition, from misfiring or shocks in landing. The instrument does not interfere with the ignition.

When there is one engine and the engine and propeller are on the fuselage, the instrument is placed in the pit or on the in strument board; with the switch directly on the casing 12. When there are two engines and each engine is mounted in the wings of an aeroplane, the instrument is placed preferably on one of the engine bearers, in a weather proof covering. The

switch is then mounted in the pit.

The outer end of the plunger 36 and switch handle may also be touched with luminous paint.

To test these instruments before flying, one starts the engine and moves the bar 11 by the handle 45 to the left till the cross marks appear at the opening or openings 88.

Before the engine stops the instrument is reset by pressure on the plunger 38, till the marks disappear again. Either of these two instruments, can be used also on an engine having a single ignition circuit and one set of spark plugs.

My invention may be used on prime movers other than gas engines, if provided with electric circuits essential to'regular operation. 1

The types of instruments shown in Figures 1 to 5 inclusive, and Figures 10 to 14 inclusive are alike in their main characteristics. Each comprises a bar or element 11 for affecting an electric ignition circuit, either by breaking it or grounding same;

and in each there are parts of said circuit, preferably inside the casing, associated with the bar 11. In neither is the bar 11 part of the circuit. In Figures 1 to 11 inclusive the conducting means in the casing comprises parts 73, 23, 7 1, 75 and 76; and in Figures 10 to 14 inclusive, 73, 98, 76, 75, 100 and 102. Both forms include the means 45 for testing purposes, and the plunger or plungers serving as means to return the spindle or spindles 76, and enable the ignition system to resume operation.

The spring 42 is chiefly useful as means for desynchronizing; that is, if the bar 11 should oscillate in unison with the ordinary vibrations of the engine, the spring 42 will revent these oscillations from causing the ar to stop the engine under ordinary conditions when no accident has happened.

Screws 80 can be adjusted from the lower side of the bar 11 to fix the point at which the elements 3 1 and 74 will be engaged and made to release the dogs 75.

Having described my invention what I believe to be new and desire to secure and protect by Letters Patent of the United States is 1. The combination of an element mounted to be movable in response to a shock, a pair of springs engaging said element, means for adjusting said springs, and a third spring adjustably mounted adjacent said element to prevent operation thereof except under predetermined conditions.

2. Mechanism comprising a casing, a pair of conductors leading into said casing, a pair of conductors leading out of said casing, elements for electrically connecting said conductors, a pair of spindles having dogs engaged by said elements, an element in the casing mounted to move in response to a shock to actuate said first-named elements to release said dogs, indicating members carried by the casing and visible from the outside of same, arms on said spindles to control the position to said members, a second arm on each spindle and a plunger for engaglng said second arms to turn the spindles and restore said dogs to engagement with said pivoted elements.

3. The combination of a pair of contact elements, a dog to press the same into engagement, a catch for holding the dog out of operative position, and an element to be moved by a shock to release said catch.

4. The combination of a casing, a con doctor in same, a spindle carrying a dog connected to said conductor, a contact element in circuit with said spindle, a seond conductor connected to said element, another contact element adjacent said first named contact element, a pivoted element engaging said dog, a pivotally mounted bar to move the pivoted element to release the dog, whereby the dog will cause the contact elements to engage, an electrical conductor connected to said seond contact element, an arm on said spindle and an indicating member controlled by said arm.

5. The combination of a casing having an opening, amember bearing an indication, a spring engaging said member to move the indication into registry with said opening, a spindle having an arm engaging said mem ber to keep said indication out of register with said opening, a dog on the spindle, an element to engage the dog, and a spring to move the spindle to release said member when the dog is disengaged from said element.

6. The combination of a casing having an opening, a member bearing an indication, a spring to engage said member to move the indication into registry with the opening, a spindle having an arm engaging said member to keep same out of indicating position, a dog on the spindle, an element to engage the dog, a spring to move the spindle to release said member when the dog is disengaged from said element, another arm on the spindle and a plunger to engage said arm and return the spindle, the dog, and the member.

7. The combination of a pair of contact elements, a spindle, a dog thereon, an element to engage and release the dog, and a spring to cause the spindle to rotate the dog when released to make said contacts disengage each other.

8. The combination of 'a pair of contact elements, a spindle, a dog thereon, an element to engage and release the dog, a spring to cause the spindle to rotate the dog when released to make the contacts disengage each other, an arm on the spindle and a plunger to engage the arm and make the element and dog reengage each other.

9. The combination of a pair of spring contact elements, a releasable dog to move said elements into engagement, a member, and an arm movable with said dog to permit said member to assume an indicating position when said elements are in engagement, a second arm movable with the dog, and a plunger to engage said second arm to return the dog and said member.

In testimony whereof, I have signed my name to this specification this 17th day of January, 1919.

THEODORE DOUGLAS.

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