US1592487A

US1592487A - Automatic wind-vaue sight

Info

Publication number: US1592487A
Authority: US
Publication date: 1926-07-13
Anticipated expiration: 1943-07-13

Description

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July 13,1926. 1,592,487

w. F. GERHARDT AUTOMATIC WIND VANE SIGHT Filed May 17, 1923 2 sheets-sheet 1 Cv v s www.

July 13,1926. 1,592,487

W. F. GERHARDT AUTOMATIC WIND VANE SIGHT Filed may 17', 1923 2 shuts-sheet 2 (j Aj/7( Eltromw Patented July 13, 1926.

UNITEU STA'iES PATENT GFFICE.

AUTOMATC WNDnVANE SIGHT.

Application led May 1.7, 1923. Serial No. 639,580.

This invention relates to instruments of wind vane sight type to direct the re of a machine gun so as to compensate for the speed of the firing aircraft.

In all flexible aerial machine gun installations a wind vane sight is used to compensate for the speed of the airplane upon which the same is mounted. The principle of the ordinary wind vane sight is well known. These sights heretofore, however, have not been adapted to compensate for various speeds or to accurately operate in various densities. It is, therefore, the object of the present invention to overcome the difficulty and unreliability above referred to by providing means for automatica-lly varying the position of the sight member in proportion to the speed of the airplane through the air, thus enabling the pro er lead to be obtained on the enemy cra t and provide a much greater accuracy in firing.

A second object of the invention is to provide a compensating device in an automatically adjustable wind vane sight which will correct for changes in the air density and permit the sight to work accurately at any elevation above the earth.

Further objects will become apparent as the invention is more fully set forth in the attached specification and claims.

In the accompanying drawings- Fig. 1 is a perspective view of the assembled automatically adjustable sight.

Fig. 2 is a transverse section of the sighting member showing the manner in which it is mounted upon the support.

Fig. 3 is a plan view, partly in section, of the wind pressure vanes and the housing therefor; and,

Fig. 4 is a vertical section through the housing.

Referring to the drawings by reference numerals, a swivel supporting post 1 is mounted upon a base 2 to rotate about a. vertical axis, which is carried upon the, forward part of thermachne' asiiitable mannen Upon the supporting post 1, are pivotedly mounted two extensible arms 3 and 4, mounted by means of pivots 5 and 6, respectively. The arm 3 consists of a tubular member 7 which slidably supports a rod 8; the arm 4 is constructed in a similar manner. These slidable rods or arms support a vertical rod or standard 9 by means of pivots 10 and 11 and this standard carries a sighting bead at its upper end. A flexible Bowden wire 11 is attached to the sliding rod 8 and extends rearwardly through the tubular member 7 and through a flexible casing 12. A similar wire 13 extends through a casing'14 and is connected to the rear end of the lower sliding rod in a similar manner. These

wires

11 and 13 are operated in a manner to be hereinafter described.

In order to vary the length of the extensible arms, a supporting housing 15 is mounted upon the rear end of the arm 4, and is provided with two vertically extending

vanes

16 and 17 which serve to align the whole device with the wind about a vertical axis. The upper and lower surfaces, 18 and 19 of the housing, form horizontal air surfaces which align the extensible arms, 3 and 4, with the wind about a horizontal axis. If desired or found necessary, addi tional horizontal vanes may be provided on the sides of the housing. In order to supplement the action of the top and bottom sides of the housin the entire device is balanced about the pivots, 5 and 6, by means of counterweight 2O rigidly'connected t-o the lower extensible arms as shown in Fig. 2.

Vertical vanes

21 and 22 are rigidly mounted upon carriages 23 and 24, respectively, by means of short arms extending through slots in the sides of the housing. These carriages are guided and carried in a longitudinal direction by means of the supporting

rods

25 and 26 which are mounted upon suitable supports in the ends of the housing. A spring 27 is provided on each rod between the carriage and an adjustable stop 28 provided on the rear end of each rod. These springs tend to force the wind vanes forwardly against the action of the wind which tends to force them to the rear. The two

carriages

28 and 24 are connected by means `of a rod 29 which is rigidly attached to each carriage. The motion of the wind vanes as they travel in a longitudinal direction is transmitted from this rod 29 by means of a cam slot 80 on a lever 31 pivoted at 32 upon the housing. An extension 33 is provided on the lever 31 and a right angular extension 84 is provided on the extension 33 and integral with the same. The lower end ot the lever extension 34 is pivotally connected to a rod 35 which is connected at the point 36 to a wire 37 which is connected to the two wires 1l and 13 so as to operate these wires in unison and equal amounts.

A closed metal bellows 38 is rigidly connected at its upper end to extension 33 ot' the operating lever and at its lower end is pivotally connected to a rod 39 which is pivotally connected at its lower end to the center of the rod 35 and serves to guide the rod 35 as the latter is moved by the operating lever. This metal bellows serves as a compensating device to correct for changes in air density, as it will be seen that when the device is operated in raretied air the pressure against the

vanes

21 and 22 will be less for a given speed than when operating in a denser air, and, therefore, in order to move the sliding arms the correct distance in this rareed air, the metal bellows containing air at atmospheric pressure will expand due to the lessened external pressure on the same so as to suitably position the rod 35 and exaggerate the movements of the wire 37 due to the movements of the Operating lever 3l.

The cam slot 30 is suitably designed so that the backward motion ct the

vanes

21 and 22, which is proportional to the square of the velocity at a given density ot the air, will be transformed to a forward motion of the wire 37 which will be proportional to the forward velocity at this density. At different densities, the metal bellows will correct the motion of the wire so that it will be compensated to give the correct motion to the sliding arms. And as the sight supporting standard together with the support l constitutes a parallelogram with two horizontal variable sides the length of which is exactly proportional at all densities to the true airspeed; it is, therefore, seen that an automatically adjustable wind vane sight is provided which will be ycorrect at all speeds thus enabling the proper lead to be obtained in aiming the gun.

I claim:

l. In a wind vane sight, a support, a sight ing member, a slidable arm 'carrying said sighting member and mounted on said support, a wind pressure operated control unit arranged in the airstream at a distance from said sighting member, and means for iin parting movements to said slidable arm, actuated by said control unit.

2. In a wind vane sight for aircraft, a support, a sighting member, a slidable arm carrying said sighting member and mounted on said support, a wind pressure operated control unit arranged in the airstream at a distance from said sighting member, means for imparting movements to said slidable arm actuated by said control unit, and yielding tensioning means for said control unit.

3. In a wind vane sight for aircraft, in combination, a support, a sighting member, a slidable arm carrying said sighting member pivotedly mounted on said support, a wind vane for controlling the movements of the arm and sighting member about the axis of the pivot, a wind pressure operated control unit arranged in the airstream at a distance from said sighting member andmeans for imparting movements to said slidable arm actuated by said control unit.

4;. In a wind vane sight for tire arms, a support, means for mounting said support to rotate about a substantially vertical axis, a sighting member, a slidable arm carrying said sighting member pivotedl mounted on said support, wind vanemeans tor controlling the movements of the arm and sighting member about the vertical axis and the axis of said pivotal mount, a wind pressure operated control unit arranged in the airstream, means for imparting movements to said slidable arm actuated by said control unit so that the distance between the vertical axis and the sighting member will be substantially proportional to the relative velocity of the air and sight.

5. In a wind vane sight for guns, a support, means for mounting said support on the gun so as to rotate about a substantially vertical axis, a pair of extensible arms pivotedly mounted on said support, a sighting bead carried by said arms, means for keeping the bead and support aligned with the wind direction, and means for changing the effective length of said arms comprising a wind pressure vane, a yielding means acting on the vane against the torce of the wind, and an auxiliary means for compensating for change in air density, whereby the effective length of said arms will vary in proportion to the airspeed.

6. In a wind vane sight, a support, means for mounting said support so as t0 rotate about a substantially vertical axis, a pair of extensible arms pivotally mounted on said support, a sighting bead carried by said arms, means for keeping the bead and support aligned with the wind direction, and means for changing the effective lengths of said arms comprising a wind pressure vane, a spring connected to the said vane and acting against the torce oi the wind, means for inter-connecting the vane and arms so that the eiiective length of the arms will be proportional to the airspeed and a device inter` posed in said last mentioned means to correct for the changes in air density.

7. In a wind vane sight, in combination, a support, means for mounting said support so as to rotate about a substantially vertical axis, a pair of extensible arms pivotally mounted on said support, a sighting bead carried by said arms, means for keeping the bead and support aligned with the Wind direction and means carried by one of said 5 arms for changing the effect-ive length of said arms comprising a Wind pressure vane held yielding at all times at right angles to the Wind direction, a yielding means acting on the Vane against the force of the Wind and an auxiliary means for compensating 10 for changes in air density comprising a link operated by a closed flexible bellows, Whereby the ejeetive length of said arms will vary in proportion to the airspeed.

In testimony whereof I afiix my signature.

W. FREDERICK GERIIARDT.