US1839194A - Canard type airplane - Google Patents

Description

Filed .July 5, 1929 J. BLoNDlN 1,839,194

CANARD TYPE AIRPLANE 2 Sheets-Sheet 1 Jan. 5, 1932.

J. BLoNblN I 1,839,194

CANARD TYPE AIRPLANE Filed July 5, 1929 2 Sheets-Sheet 2 l Avy/enviar; j2me/127e BZoWdz'w,

Patented Jan. 5, 1932 PATENT OFFICE JOSEPH BLONDIN, OF LOS ANGELES,v CALIFORNIA CANARD TYPE AIRPLANE Application led July 5,

This invention relates to aircraft and particularly to airplanes of the canard type comprising main lifting surfaces or wings and a loaded or weight carrying front elevator supported by a framework extending forward of the main wings;

Aviation history chronicles'many canard types of airplanes which flew more or less successfully and all of which were characterized 1o by superior qualities of fore-and-aft stability compared with other types of airplanes. But they were all inferior in response to rudder action; i. e., to being steered sidewise.

An object, therefore, of this invention is to successfully modernize the canard-type airplane retaining and improving its qualities of fore-and-aft stability, and endowing it with eiiicient rudder-action which it has heretofore lacked.

Pioneer canard-type airplanes were also defective in that element of structure which was depended upon to support the front elevator. In the case of biplanes such element was an Outrigger frame attached to and projecting forward from the wings. Such outrigger-frames were inherently weak because of length and lightness, and lack of 'resistive factor to lateral and tortional stresses. In the case of monoplanes such elevator carrying element was a central, quadrangular or box-- truss frame forming an integral extension of the nacelle orV car and was supported clear of the ground by the running gear which` consisted, generally, of two side wheels at the rear portion of the frame, and one central wheel set far forward on the frame. This frame, while capable of being made more rigid and stronger for a givenweight than the biplanes Outrigger was, however, handicapped by being made to also carry the said forward wheel unit of the running gear thereby being forced to absorbthe violent stresses placed on the wheel-unit at take-olf and landing, and ground running, and these stresses werel imposed upon said box-frame close to its extreme forward end,A or at `its point of free overhang-ff or unsupported leverage.

A further object, therefore, is to provide a front-elevator supporting structure of 50 maximum rigidity and resistance to all ver- 1929. Serial No. 376,280.

tical, lateral and' torsional stresses that might be imposed by the elevator, and to eliminate the conventional forward wheel-unit as used in the past, thus relieving the forward extending, free overhang portion of the frame from all landing stresses and limiting it' to its single, proper function of supporting the front elevator. To this end I have invented and provided an inverted, triangular-trussed keelframe which not only supports the front elevator but underlies and directly and incidentally supports all other constructional and operative elements of the airplane proper. By the present invention for over two-thirds of its length the keel frame supports the nacelle orcar and is in turn reinforced and strengthened by the rigidity and inertia of the car and its loads.

A further object is to provide a skid frame of inverted triangular form whose rear and lowermost end is adapted to engage the ground when landing and further, whose apex-beam or keel will act. as a runner at its rearmost end and at any other portion in its length, in emergency, such as might occur if 'I5 the wheels dropped into a ditch or the furrows of a plowed field. l Note that in either case this invention designs the sln'd-feature to function' directly under the car whose rigidity and inertia will absorb all landing stresses.

More directly, the landing gear proper consists, here, of the rearmost and lowermost portion of the triangular keel-frame in combination with a plurality of side wheels widely spaced laterally from the sides of the car of the airplane; the keel-frame having a yield'able shoe. All previous canards were characterized by the employment of a single elevator surface carried forward of the machines center of gravity, whose carrying ca-l pacity, as a wing, and directional capacity, as an elevator was depended upon to govern the inherent stability, trim and climbing and diving maneuvers of the airplane.

An additional obj ect of this invention .is to supplement the above referred to conventional front elevator and materially improve the control of such canard type planes by adding a rear elevator carried rearward of the machines center of gravity and hinged to the rear wing-bar of the main lifting planes; this being entirely original conception. in canard type airplanes, and greatly enhancing control of the machines fore and aft balance and direction, and made effective distinctively by my provision wherein the center of gravity of the machine, in flight, is maintained forward of the main liftmg wings and not below as heretofore the Case.

Another object is to provide a superior means for aircraft steering, particularly canards, around their vertical axis. All previous canard planes were deficient in sidewise steering action, their lack of proper keel or vertical lin to complement their rudder surface being adjudged the reason for the defect.

.Now, in the first place, none of the pioneer canards, actually built carried their center of gravity sufiiciently forward.

The location of this fundamental governing point was. in most cases, positioned directly under the wings leaving insufficient leverage for the rudder to act upon. The operation of a single vertical rudder, so handicapped, resulted more in an outward skid then a true turn-a skid which immediately entailed loss of lateral stability, followed by stalling or diving effects which quickly defamed the canard principle of design.

Remedy of this defect usually took the form of extra vertical -surfaces or fins placed forward of the wings upon the framework which su ported the front elevator. These furnishe the needed fulcrum for the rudder to act against but they, at the same time, furnished an added fin surface with long leverage from the machines center of gravity for any and everv side gust or current of wind to act upon. Thus the rudder action was again minimized-or even nullified--the machine in such case being turned down Wind with a consequent greater loss of lateral stabilitv than in the former case. Also, a single rudder located followingr the exact longitudinal axis of any vessel acts detrimentally in the sense that the drag component serves to retard the speed of the vessel and. consequently, to reduce fluid reaction against the rudder surface; action whose efficiency in-l creases as the square of the speed of the vessel. Obviously, such rudders contribute only the side component or thrust of their overall possible steering eiciency. I seek to obtain a maximum effective steering action through, first-placing the center of gravity of the machine at a point situated at least 25% of the wing chord in front of the leading edge of the main wings thereby increasing the rudders leverage to said center: secondby provision of twin rudders operative outward only as to the ships longitudinal axis: third-provision of means to operate each twin rudder independent of the other so that but one is effective on turns while the other lies in the bed of the wind or at zero angle to the fiight line: fourth-the provision of rudders placed off the longitudinal axis of the machine at a considerable distance so that each rudder acts jointly in response to side thrust and to backward drag as Well, on lever arms whose magnitudes are measured forward to the center of gravity of the machine and laterally to the long axis respectively: fifth-the provision of a preponderance of constructional vertical surfaces rearwardly of the center of gravity of the machine so that all side-gusts or currents of wind, in flight, will tend to turn the machine into the wind; the correct position for maintaining the stability of the machine.

A still further object is to provide means to utilize the drag effect of the rudder conjunctively to reduce the momentum of the machine when landing and thus shorten the run after first touching ground. To this end means are provided for separate turn and for concurrent brake action through the instrumentality of rudders.

Still another object is to provide window frame struts so disposed as to rise vertically from lateral beams from the chassis to superjacent main cantilever wings and to perform the important function of supporting the wing at a material distance outward from the nacelle or car, thus reinforcing the cantilever wing by reducing the length of its free overhang. In full cantilever wing machines the overhang extends from the fuselage or car side to the extreme tip of the wing.

In the present disclosure the wings overhang extends only from the window-frame struts outward to the tips of the wings; a reduction in length furnishing' greater stiffness to the wings and reinforcement against compression and bending strc-'ses in the intcrnal structural nwmhers of' the wings.

My invention has for particular object-1 therefore, first--the improwuuut of thc air plane type of alrciaft and -fsl till :ill fanard type airplanes by infurlfvung the keel frame as '1u element ofthe landing gear and to unite, .strengthen and .support all other elements of the machine; sccfutlmthc provision of a canard type which places` the center of gravity entirely forward of its main lifting planes` and third-the provision of operative means improving the stability and the control of the balance and of the flight direction of the machine.

Other objects, advantages and features of construction, combination and details of means and mode of operations will be made manifest in the ensuing description of the herewith illustrative embodiment; it being understood that modifications, variations and adaptations may be resorted to within the spirit, scope and principle of the inventiffn as it is more directly claimed hereina er.

ills

Figure 1 is a plan of the airplane. v Figure 2 is a side elevation thereof. p

Figure 3 is a front elevation, and

Figure 4 is a diagram showing the relative position of the rudders to the ships center of gravity. v

In the illustrated ship a front elevator A is disposed well ahead of the main liftin surface or wing B; both being solidlyxe on a skeleton chassis into which is built the nacelle or car N. The skeleton extends Well forward from the car and is characterized by an inverted triangular or V-section keelframe K which presents a bottom, longitudinal apex-beam or keel K the full length of the ship; having at its rearend a hinged heel piece P supported yieldably by a bow spring P based on the rear end of the body frame.

The wings include spaced upper crossbeams I-I on the top of the cabin of the car N and each Wing is secured to the top stringer of respective, outboard, vertical windowframe struts J whose posts stand on laterally projecting, transverse beam I- which thus serve to greatly strengthenthe overhead wing structure.

The intraspaces of the window-frame struts J are provided with fin-surfaces L in front of rudders E hinged to the vertical, rear posts of the struts; the latter having dia onal braces which reinforce and sti en the fin frames J and form trusses whose king post is the nacelle or car.

Above the forward or nose part of the keel-frame K is a supplementary V-frame K which materially stiifens and reinforces the frame K as the support for the front elevator and incidentally forms a harmonizing superpart for the keel-frame.

A notable feature of this airplane is the arrangement of the main wing B at the extreme rear of the chassis and the placing of the car and the front elevator to produce the center of gravity of the machine well forward of the main wing; preferably at a minimum distance equal to 25% of the wingchord, andbeing indicated by the point G; whereby to achieve inherent stability.

The ship is provided with ground wheels W widely spaced from the sides of the keelframe and with the keel-beam K or heel` P providing for three-point landing contact and rest supports. The Wheels are forward of the rear end of the frame K and should they drop into surface depressions the keel K comes into effect as a sliding skid.

The-rudders 'E are independent and are operated by independent foot treadles F so that only that rudder is actuated which is on the side of the ship relative to an intended turn; the right foot controlling the right rudder for a right turn and the left foot for a left turn in the usual manner. Another advantage of this system is that, at will, the

l pilot may throw out both rudders at one time v with the result that a decidedbraking effect isaccomplished; this being effected by pressure of both feet on the rudder controls at the to the front elevator A, and a rear elevator.

surface or flap B hinged to the trailing edge of the plane B and connected to the front flap A by a control means of conventional form operative to concurrently tilt the flaps in opposite directions; i. e. the forward one up and the latter down to pull the nose down and vice versa to raise the nose, so that each flap acts with a cooperative movement about the-center of gravity G of the machine.

It will be noted that there is no material i vertical surface at the nose ofthe fore-rig frame carrying the front elevator means thus eliminating objectionable counteraction by side pressure of the air when turning and avoiding side drift of the head due to lateral air currents.

The driving propeller is here shown as at vthe rear of the car N.

In the take-off position the machine rests on its three-point base P-W-W, with the nose of the ship directed well up from the ground line Y.

Lateral stabilizing ailerons O are hinged to the main wing B outward of the medially dis osed rear elevator element B.

- hat is claimed is:

1. In a canard-type airplane, a triangular, trussed skeleton keel-frame whose members are permanently attached to form a unitary longitudinal girder with its apex-beam lowermost and whose upward base forms a platform supporting at its forward `end a front elevator, at its median portion supporting a superimposed car and its y.rear end having a superimposed main`wing structure the 1nverted beam forming a landing tail.

2: In a canard airplane, an integral triangular, trussed keel-frame which underlies and supports the machines front elevator surfaces and a superimposed car and propel ling means and main wing, and lateral iin frames carried by the keel-frame and having trailing rudders; said frames forming outboard supports for centil-ever parts of the wing.

3. In a canard airplane, a triangular-section skeleton keel-frame with its apex-beam downward and constituting a ship-length keel and its upward base forming a platform for superimposed planes and superim osed car structure; the rear end of the said am forming onepoint of landing and resting support for the airplane.

4. In a canard airplane, a triangular-section, trussed keel-frame with its apex-beam downward and forming a ship-length keel, and a supplementary, triangular nose frame with its base imposed on the upward base of the keel frame.

5. In a canard airplane, a triangular, trussed keel-frame with its apex-beam downward and whose extention represents the over-all length of the airplane, the rear end of the said beam formin a landing support, and wide spaced groun wheels at the sides of the frame and forming with the rear end of the beam a three-point landing and standing support.

6. In a canard airplane, a fixed forward, elevating plane, a rearward main plane, and cooperative elevator flaps on said planes and respectively fore and aft of the ships center of gravity.

7. A canard airplane having, in combination, a front elevator having a trailing edge flap, and a main wing havinvr a trailing edge Hap coupled to the front ap for coaction with 'respective movements in opposite directions.

8. A canard-type airplane in which the center of gravity is forward of the leading edge of the main plane at a minimum distance equal to 25% of the chord of the wing, and having elevator means including control flaps fore and aft of the center of gravity.

9. In a canard airplane, vertical rudders having laterally outboard supports and spaced beyond the respective sides of the long axis of the machine and operative separately to make a respective turn of the machine; the idle rudder being free to hang at zero angle to the line of flight and adapted for concurrent operation in opposite outward direction to serve as brakes, the braking rudders being disposed rearward of the center of gravity of the machine.

10. In a canard airplane, a pair of vertical rudders each offset from the longitudinal axis of the machine and rear of its center oi gravity and separately operative; whereby the active rudder induces a backward drag acting on a leverage measured sidewise from the rudder post to the said axis and simultaneously induces a side thrust acting on a leverage measured forward from the rudder post to the center of gravity of the machine so that each rudder has a double turning couple in steering action and means for concurrently turning the rudders in opposite directions outwardly as brakes 'ective rearwardly of the center of gravity of the machine.

11. In a canard air lane, a chassis including spaced, horizonta beams extending laterall of the ships axis, outwardly spaced win ow-frame struts standing on said beams and whose intra-frame spaces have fin surfaces; the bottom stringers of the frames bein attached to said beams and whose' top stringers are secured for their length to the arch of the airplanes main wing; said frames reducing the length of the free overhang of the wing structure.

12. In a canard air lane, a chassis including spaced, horizonta beams extending laterally of the ships axis, outwardly spaced window-frame struts standin' on said beams; the bottom stringers of the frames being attached to said beams and whose top stringers are secured for their length to the arch of the airplanes main win said frames reducing the length of the ree overhang of-thc wing structure.

13. In a canard airplane, a main wing and rudder supports fixed thereto laterally of the ships axis, one on each side and rear of the ships center of gravity, and independently operative rudders on said supports, and means to set the rudders concurrently as brakes.

JOSEPH BLONDIN.

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