US2611810A - Airplane warning system - Google Patents

Description

P 1952 L. M. GREENE 2,611,310

AIRPLANE WARNING SYSTEM Filed Feb. 18, 1950 INVENTOR.

[6min GR'nvF .4 ro/zA/sy Patented Sept. 23, 1952 UNITED STATES PATENT OFFICE AIRPLANE WARNING SYSTEM Leonard M. Greene, Scarsilale, N. Y.

Application February 18, 1950, Serial No. 14 L986 1 Claim.

This invention relates to airplane warning systems. More particularly, my invention pertains to aural warning systems for airplanes.

At the present time it is customary to advise an airplane pilot of certain dangerous condi tions. Typical of these conditions are failure to lower the wheels before landing and assumption by an airplane of a stall-approaching attitude with respect to a local air mass.

Heretofore the pilot usually was warned of such condition of imminent danger visibly, as by lighting or blinking of a lamp, tactually, as by shaking the control stick, or aurally as by sounding of a horn or buzzer. It is preferred to give the signal aurally since, under proper conditions the pilot cannot fail to perceive it as he might a visible signal and since present-day tactual signalling mechanisms are expensive, heavy, awkward and complicated, require considerable power, and often cannot fit into the space available. However, conditions are not always proper for hearing aural signals. For example, a pilot often wears earphones during flight and these, or the cups in which they are mounted, shut the pilot off from the noise of his surroundings so that, unless the aural signal is very loud, he cannot hear it. On the other hand, if the signal is loud enough to be heard by a pilot wearing earphones, it is much too loud for the pilot when the earphones are removed. Moreover, on occasion, due to the relative volumes at the pilot's ear of the aural warning signal and a radio loudspeaker, the loudspeaker may drown the aural warning signal.

It is an object of my invention to provide an airplane aural warning system which is not subject to the foregoing defects.

More specifically it is an object of my invention to provide an airplane warning system of the character described which imparts an aural warning by way of the electro-sound translating output device or devices of the airplanes radio.

It is an ancillary object of my invention to provide an airplane warning system of the character described which sounds at least two warnings simultaneously, one in the earphones, this optionally being of a low magnitude of sound sufficient only to give notice to the wearer of the earphones, and the other a horn or buzzer cockpit warning which is loud enough normally to be heard by anyone in the cockpit not wearing earphones.

It is another ancillary object of my invention to provide an airplane warning system of the character described which imparts an aural warning in the earphones and loudspeaker so that, regardless of any possible condition, the warning will be heard.

It is another object of my invention to provide an airplane warning system of the character described which comprises relatively few and simple parts, is easy to manufacture and inexpensive to install, and is highly effective in operation.

It is another object of my invention to provide an airplane warning signal of the character described which is of such construction that it is normally isolated from the radio except during warning conditions.

Otherobjects of my invention will in part be obvious and in part will be pointed out hereinafter.

My invention accordingly consists in the features of construction, combinations of elements and arrangements of parts which will be exemplified in the device hereinafter described and of which the scope of application will be indicated in the appended claim.

The single figure illustrates one of the various possible embodiments of a warning system constructed in accordance with my invention.

In said system the reference numeral 10 denotes a device which is responsive to the imminence of danger. Said device includes an electric switch 12 which preferably is of the normally open type and, desirably, is snap-acting. By way of example the device may be one such as is illustrated in my United States Letters Patent for Stall Warning Device for Airplanes, No. 2,478,967, dated August 16, 1949. Said device constitutes a vane 14 whose forward edge is free and juts a slight distance from the wing into the air stream. The vane is pivoted adjacent its rear edge and is arranged to operate the switch 12.

Said vane is located on the leading edge of the wing within the range of influence of the shifting separation point, being so disposed that it will move suddenly from the position it occupies during normal flight to another position upon the approach of the separation point to a predetermined angle ahead of stall. Thus, when the airplane approaches a stalling attituda'the vane will flip from one to another position and in so doing will cause the normally open contacts of switch l2 to close.

It will be understood that the switch 12 may form a part of some other condition responsive device, as for example it may form part of a landing gear warning. In such cases the switch example.

is closed when the landing gear is up, is adjacent an operating part for the landin gear, and is in series with a throttle switch which is open as long as the throttle control is above a certain position. When the throttle control moves below this position its associated switch closes and, ii the landing gear is not fully down, the circuit through both switches is completed.

One contact ofthe switch 12 is connected to ground by a lead wire 16. The conductive fuselage of the airplane may serve as a ground and constitute the return or neutral lead to one side, for instance the negative side, of a battery It or other suitable source of power which is grounded by means of a lead wire 20.. The'other' contact of the switch I 2 isconnected tothe, opposite pole of the battery through a lead wire22, switch 24, a lead wire 25, a vibrating type sounder 28 and a lead wire 38. V

I The switch 24 is of the single pole double throw 'type and is used ior testing and turning ofrthe .is energized it pullsthe contacts apaipmus interrupting its energizingcircuit. By adjustment of the contact spacing and tension of the spring, the irequency of vibration can be varied. Optionally "a condenser; 40 may be shunted across the'contactsitz e hie of e cont ts brmi-n m iri spa k n It will be-appreoiated thatthe sounder-fl desirably is of such physical'construction as to emit an audible warning which can be heard clearly and-easily by the pilotjover tliencjrmal; cockpit noises when the pilot is not vea 'ing earphones. Itwillbeappreciated further that any of the u types i ia n e ssi n tensed he one shown here being illustrated merely by way-of wherein a cam rotates incontact with a -plate and also; includes apair of;conta cts;which are rapidly opened and closed during rotationof the cam.

, From the means a Waite e enstates when the switch closed in itsleftj-hand position and when the airplane approaches the condition to whichthe device i0; is responsive, the sounder will emanate an auralwarning, I

The airplane has; a radio- .42 whoseputput is delivered toa pair of wires 34,45 running 'to a double-pole,'doubleethrow switch A801 any other equivalent type of switchwhichenables the'radio selectively to energize either aloudspeaker 5,9 -'or a pair of earphones 52hr both by'use' of a suitable type oi switch; i: e. a double jack.

In: order to irnp'ress a s'ign'al ffroTd-the sounder 28 across the output of the radio, I cbrinec'tone 34' to prolong Thus the sounder can be cf the; type -upon approach to a specified dangerous condition, e. g. stall, the device it) is actuated by operation of the vane it to close the normally open contacts of switch !2. This causes the sounder 28 to be energized and will apprise the pilot of the imminence of danger. If, however, the radio should be on, its output emanating either through the loudspeaker or through the earphones may drown the warning of the sounder were the'present novel system not; employed.

Nevertheless, the warning-will be heard-over that sound outputdevice. ofv the "radidwhich happens to be' in operationforboth if suchbethe case. Moreover it will be heard in such device even if the radio is not operating. ".[hi s occurs because,

as soon as switch l2vis closed, a circuit is'complet'ed from said switch throughtherelay"opcratin coil 86 to; the battery. "Energization of therelay coil closes the jpairfof contaotsflfifi, 62, thus jcornpleting the circuit from 'the"sounder solenoid 38 to the outputoftheradio. H

When the sounder opensand'closesits contacts 32, fi l, the'condenser E0 1 and sounder solehold as W111 impress in the radio 'outputa potential which ismodulated' at the audio frequency of the sounder. Said "potential will be translated into sound at the loudspeaker and/or'ear- 1 phones. Since the superimposed signal isof the sam frequency as the sounder signal, it will be recognized by the pilot as the warning of the sounder to which he has been trained to take appropriate corrective action. V v I Attention'isdimcted to the fact that, until the "switch i2 'hasbeen'closed, no'extraneous' electric impulses will bei'mposedupon the'radio output.

This is due to the fact that themeans 'io'riinpre'ssing the signalin ther'adio outputisn'ot connected to said output until such timejas the "switch 12 is closed. That is ,tojsaypnljessj the switch I2 is closed thenormally openipainof "contacts 55, '62 will isolate the"radiooutput.

If'itisdesilecl to check the "sounderjand coil 66, the switch 25 is swung to its righthand -position. This should energize said coil and the sounder 23, causing a warning signalto be'heard in the loudspeaker j and/or' earphones.

fl't. thus will be 'se'en that I 'haye'provided a device 'whichachieves all the bbjje'ctsofi invention and is well adapted to meet the conditions of pra'cticaluse. V g 4 H As various possible embodiments might be made of the above invention, and as various changesjmight be made in the embodiment above s'e't forth, it is to be understood "that' allmatter herein describedor shown in the accompanying drawing, is to be interpreted as illustrative and "not in a limiting sense.

Having thus described my menu-tn, I claim asnew and desireto secure by Letters Patent:

p I For use in fan airplanehavinga'radio and a source of electric power, and whereihfanactuator is provided which upon the imminence b fdanger c s "sw tch: that ompl t fc ff t "source 'of-power: an electrically actuable-sounder,

means to connect said sounder in series in the circuit between the switch and the source of power, said sounder including a pair of contacts in the circuit of the sounder and means to rapidly open and close said contacts at an audio frequency when the sounder is actuated, a relay having an operating coil and a normally open switch which is arranged to be closed upon energization of said coil, means to connect said coil in the circuit between the switch and the source of power, and circuit means to impress the potential of said contacts upon the output of the radio,

. 6 said last-named means being connected to the radio output through said relay switch.

LEONARD M. GREENE.

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

UNITED STATES PATENTS Number Name Date 2,051,827 De Florez Aug. 25, 1936 2,386,992 Trott Oct. 16, 1945 2,552,331 Lamb May 8, 1951

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