US1808342A - Airplane control - Google Patents

Description

June 2, 1931. R. CHILTON AIRPLANE CONTROL Filed May 13, 1929 3 Sheets-Sheet l I N VEN TOR.

ATTORNEY.

June 2, 1931. R. CHILTON Q 1,308,342

AIRPLANE CONTROL Filed May 13. 1929 3 Sheets-Sheet 2 I N VEN TOR r BY w ATTORNEY.

R. CHILTON AIRPLANE CONTROL June 2, 1931.

Filed May 13, 1929 3 Sheets-Sheet. 5

JNVENTOR.

ia/a/za fi/m 9} W ATTORNEY.

Patented June 2, 1931 UNITED s A'rEs PATENT OFFICE ROLAND CHILTON, or KEYPORT, NEW JERSEY, ASSIGNOR, BY MESNE ASSIGNMENTS, TO

AEROMARINE PLANE & moron. COMPANY, INC, OE-KEYPORT, NEW JERSEY, A con- PORATION OF NEW YORK AIRPLANE CONTROL Application filed May 13,

This invention relates to horizontal control means for airplanes and comprises new mechanism giving improved control of the atti-' tude of the plane in flight and particularly at the minimum flying speed or stalling point whereat conventional controls are, in general, inefi'ective. The present embodiment constitutes an improvement over my co-pending application Serial No; 356,128, filed April 18, 1929.

As is well known, the lift of an airfoil increases with an increase in the angle between the airfoil chord and the actual flight path (the angle of attack or angle of incidence) up to a certain maximum angle identified with the burble point whereat the streamline flow over the wings breaks down and a sudden loss of lift occurs resulting in an actual drop of the wing in flight. This action is known as stalling.

A prime object of the present invention to provide a new organization of long tudinal and lateral control surfaces and interconnecting mechanism whereby full control is maintained while the wings and fixed tail surfaces of the plane are in the stalled condition so that the lane ma be surely maneuvered, as for landing, at re atively lower forward speeds than is safe with the conventional arrangement wherein the control surfaces partake of the pitching movement of the plane and therefore, lose their effectiveness by stalling with the fixed surface to which they are hinged.

For landing into restricted areas and over obstructions, a steep glide path is desirable but no benefit results when-this is obtained by diving the ship, as excessive distance is absorbed in losing the resulting 111 h speed, i. e., in leveling off before the stal ed speed necessary for landing is reached.

The desired slow speed and resulting steep path of approach may at present be secured by side slipping or squashing, the latter- 1829. Serial N0. 362,652.

titudes is regarded as dangerous, except in calm air and with inherently stable ships, because of the accompanying loss of effectiveness in the usual control means. I

The range in longitudinal attitude (pitch) between squashing and a stall (endangering complete loss of control with the usual ailerons and horizontal stabilizers) is relatively small and it requires considerable assurance and skill on the part of the pilot to maintain the ship within this range with the greatly lessened effectiveness of the normalhundreds of feet of altitude before sufficient,

speed for adequate control is regained, even when the nose-over is fortunately, not accompamed by an excess drop inone wing. The rotation of the plane initiated when this occurs may become confirmed into auto-rotat on or spinning which tends to lift the nose while the actual flight path is steeply downwards and the ailerons are normally ineffective 111' this condition, which may require over a thousand feet for recovery, for which a preliminary further depression of the nose to correct the stall is necessary. The liability to this spinning-in isthe reason that, with conventional controls, flight near the stall at moderate altitudes is regarded as a dangerous practice, although it is used by skllled pilots for squashing-in to a tight landing.

A further object of this invention accord: mgly, is to provide longitudinal and lateral control means which will maintain immediate response after the fixed wing and tail surfaces are stalled and so permit, with safety, a prolonged stalled glide, which greatly toduces the forward landing speed, the distance absorbed in getting down over an obstruction. and the length of run after landing.

To prevent the stalling of the moveable control surfaces with the fixed surfaces, it has been proposed to dispose the hinged wing-tips (and possibly also the tail control surfaces) away from the associated fixed surfaces, but this alone will not suffice because the control surfaces, as usually connected, partake of the pitching movement of the ship and are in fact movable to a greater angle of incidence than the wings themselves and may, therefore be the worse stalled.

In the present invention, on the contrary, floatingly pivoted horizontal control surfaces are used and are inter-connected by novel control means whereby the are together free to move unitarily to ahgn themselves at all times with the actual flight path of the plane, i. e., to altogether automatical- 1y assume zero angle of incidence regardless of the attitude of the ship the control mechanism determining only the relative angles between the several movable surfaces.

Conventional horizontal control systems include ailerons near each wing tip and hinged stabilizers at the tail and the present invention is accordingly herein illustrated as applying to pivotal horizontal surfaces forming three elements spaced apart laterally and longitudinally, as usual, but preferably removed from the trailing edge of the associated fixed surfaces in' order to avoid aerodynamic interference therefrom.

Thus wing-tip type ailerons and a movable surface disposed above fixed stabilizers or tail-surfaces are preferred, and these are pivoted ahead of their centers of pressure so as to possess weather-vane stability whereby they will at all times tend to align themselves with the instantaneous flight path. Novel control means are herein provided permitting this freedom while positivel controlling the relative angle between all t ree control elements.

The supposed complication of the necessary control means is the objection alleged by many skilled in the art against three floatin elements differentially controlled, althoug the aerodynamic advantages inherent in this system are generally conceded.

A still further object of the present invention is to provide simple mechanism'easily applicable to conventional airplanes without departin from the standardized directions of contro? movement and effective to actuate three floating control elements differentially.

Various other objects and advantages of the invention will be in part obvious from an inspection of the accompanying drawings and a careful consideration of the following particular description and claims of one form of mechanism embodying my invention.

In the drawings Figure 1 is a perspective diagram of an airplane equipped with the control mechanism of this invention.

Figure 2 is a perspective view on a larger scale than Figure 1 in greater detail the control stick and associated mechanism in the cockpit of the air lane.

Figure 3 is a ragmentary diagrammatic aide elevation of the tail and its control-mem- Figure 4 is a detail of the control stick and its associated mechanism.

With reference to Figure 1, a low wing monoplane has been chosen for the purpose of illustrating this invention, it being understood, however, that the control means herein featured is applicable to any wing'disposition.

In the drawings 10 designates a conventional fuselage and 11 and 12 the right and left hand wlngs thereof respectively, said wings being provided with wing-tip type ailerons 13 and 14 pivotally mounted on the wings ahead of the center of pressure of the ailerons on shafts 15 and 16. These ailerons are suitably connected to a pair of bell crank 26 to the levers 17 and 18 so that these 'move with the ailerons. This particular type of connection is not an essential feature of the invention and any suitable means may be used, for instance, the shafts l5 and 16 may be extended and the levers 17 and 18 moved directly upon their inward ends.

Referring now to the tail control elements as shown in Figures 1 and 3, a conventional normally fixed stabilizer surface 30 may be used in conjunction with the usual fin 31 and rudder 32. The elevator or movable tail sur face 33 isin that case preferably disposed away from the fixed tail surface and mounted on a lateral shaft 34, secured to the top of the rigid vertical fin and braced at its outer ends by struts 35 from the fuselage. A control .rod 36 connects to a bell-crank lever 37 'pivoted within the fuselage and this bell crank 37 is suitably connected as by cables 27 and 28 to a bell-crank lever 38 disposed behind the control stick 19. In some airplanes the normall fixed stabilizer or tail surface is de letc in favor of a large controlled elevator and the control of this invention may be applied to such elevators without change in either form or disposition.

Referring now to Figure 2, the control stick 19 is mounted for vertical sliding on an inner tube 40 which is mounted for pivotal motion fore and aft and for rocking motion with the shaft 41 which may be extended in the usual way to engage a second stick 42 for dual contro s.

The top end of the control stick 19 is provided with a grip 43 and rigid with this outer tube at its lower end are three levers 44, 45 and 46 respectively articulated to the bellcrank levers 17, 18 and 38.

The action of the control is as follows, the words down and up being used to designate the movements of the leading edges of the control surfaces Supposing the control stick to be rocked forward, it will be seen that the ends of the levers 44 and 45 move downwardly while the end of lever 46 moves upwardly with the result that both the ailerons 13 and 14 are moved down while the elevator 33 is moved up, resulting in a depression of the nose and elevation of the tail of the airplane thus affording a double control in place of the usual elevator action, which is confined to the tail of the ship.

When the control stick is rocked, to the left, for example, it will be seen that the lever 44 is lifted and the lever 45 depressed; the vertical position of the end of the lever 46 remaining unchanged, whereby the rlght hand aileron 13 is moved up and the left hand aileron 14 is depressed which banks the ship in the usual way.

WVhen the stick is rocked diagonally about an axis corresponding with one of its three levers, it will be seen that no motion results at the associated control surface, the movement being effective in opposite directlons at the other two surfaces since the levers 44, 45 and 46 are disposed geometrically about the stick in positions to correspond to the location of the control surfaces. A consideration of these movements will disclose that the attitude of the airplane is changed around the axis about which the stick is rocked. It will further be seen that the system may be extended to any number of control surfaces, provided that the location of each lever extension on the control stick is geometrically similar in plan aspect to the location of the associated control surface. Control surfaces may accordingly be disposed-at more than three extremities of the airplane, although the disposition shown corresponds to the conventional form of airplane.

Due to the freedom for vertical plunge of the outer member 19 of the control stick, it will be seen that the attitude of the control surfaces, considered together, as not restrained and that, if the stick be held from lateral movement, all the surfaces are free to align themselves to the instantaneous flight path of the airplane. In this condition, an enforced movement of any one control surface will result in a similar movement of the other surfaces, i. e., providing the stick is restrained from rocking. This action will be accompanied by a vertical movement of the grip 43. Such an action will occur in flight whenever the attitude of the airplane relative to its flight path is changed because, the control surfaces being pivoted ahead of their centers of pressure, they will tend to align themselves with the relative air stream. Thus the vertical movement of the grip 43 is an index to the pilot of the actual instantaneous angle of the flight path relative to the attitude of the airplane. If the ship approaches a stall, for example, whereat the flight path is relatively steep, even though the nose of the airplane be on or above the horizon, the front edges of all the control surfaces will be-pointed downwards along this flight path and the control stick grip will sink to a correspondingly low position warning the pilot that he is approaching the stalled condition. The entire mechanism thus comprises in one sense, an angle-of-incidence indicator.

While the pilot. may be able to exercise some control through this vertical movement of the stick, it is intended that the leverage afforded will be insufiicient to permit him to force the control surfaces simultaneously to a substantial angle to the relative air stream. However, greater leverage is obviously provided for differential movement between the various control surfaces in response to rock: ingmotion of the stick, but the initial or zero position from which such displacements occur is always the position of alignment of all the surfaces with the instantaneous actual flight path regardless of the attitude of the airplane. .Thus excessive angles of incidence of the control surface are avoided, in opposition to the conventional arrangement where the normal attitude from which the control movements are initiated is that of the airplane as a whole wherefrom conventional controls become stalled, and therefore ineffective, at the same time that the wings are stalled as by excessive nosing-up of the airplane or from flight at stalling speed wherein the actual flight path may be steeply downward with the airplane approximately horizontal. Both of these conditions are considered dangerous with the conventional controls, although the latter is highly desirable for obtaining a steep path of descent at slow speeds as for landing.

Variations may be resorted to within the scope of the invention and portions of the improvements may be used without the others, whilst not departing from the spirit of the invention.

Having thus described my invention, I

claim 1. The combination with normally horizontal control surfaces spaced laterally and longitudinally of'an airplane on hinges, lat-- surfaces in response to lateral movement of the control member and for opposite movement of the longitudinally separated surfaces in response to lon itudinal movement of the control. y

2. In an airplane having atail and horizon tally pivoted control surfaces disposed on lateral axes respectively toward the tail andat each side of the airplane towards the front, the combination of a control member movable forwards and sideways, and means interconnecting'saidsurfaces and the control member for automatic similar angular movement of all the surfaces independently of said movements of the control member and for opposite angulation between the side surfaces and between the front and tail surfaces respectively responsive to sideways and forward movements of the control member.

3. In an airplane having longitudinally and laterally separated control surface members pivotally mounted for vertical oscillation about lateral axes, a control member movable vertically longitudinally and laterally and connected to said surface members, the whole organized forautomatic uni-directional vertical movement of all said members and for opposite movement between the laterall separated surfaces and between the long1tudinally separated surfaces in response to the gorresponding movement of the control memer. e

4. In an air lane having a rockable control stick, a plurality of horizontally pivoted control surfaces spaced in plan aspect about the airplane on lateral axes, horizontall pivoted control levers connected one to each of said surfaces and similarly spaced a art about said stick, and a cross member roc able with said stick and automatically slidable thereon for simultaneous floating action of all the surfaces and connected'to each-of said levers. 5. The combination with an airplane having a control member rockable'in all horizontal directions, of three control surfaces pivoted toward three extremities of the airplane on lateral axes, a control lever operatively connected to each surface and disposed aside the control member toward the connected surface, a three-armed cross piece at all times freely slidable on the control member by the air reactions on the surfaces and rigid forrocking motion with the control member, and links connecting each lever to an arm of the cross iece.

6. n an air lane having a stick control member, more t an two control surfaces pivotally mounted on lateral axes near the extremities of the airplane, a cross head permanently automatically slidable upon the stick and rockable therewith, and means to operably connect; each surface to a point on said cross piece situated on the side of the stick towards the connected surface.

7. In an airplane provided at three or more 'fixed tail surface so as to be out of the downof May, 1929.

ROLAND CHILTON.

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