Elastically mounted self adjusting airfoil
US RE18181 E
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w. STELZER ELASTICALLY MOUNTED SELF ADJUSTING AIRFOIL R 18 181 Sept. 8, 1931.
Original Filed July 13, 1928 keiuued Sept. 1931 Re. 1s,1si
UNITED STATES, PATENT, OFFICE WILLIAM STELZEB, OF CHICAGO, ILLINOIS, ASSIGNOR TO BENDIX AVIATION CORPORA- TION, OF NEW YORK, N. Y., A CORPORATION OF DELAWARE ELASTIGALLY MOUNTED SELF ADJUSTING AIRFOIL Original No. 1,725,222, dated August 20, 1929, Serial No. 292,358, filed July 13, 1928. Application for reissue filed August 22, 1930. Serial No. 477,152.
The invention relates to improvements in the mountin of airfoils on the fuselage of variable kinds of aircraft; and the objects of the improvement are, first, to provide elastic intermediate members between the carrying plane and the fuselage to make the latter independent of the shocks imposed on the win s by fluctuating air, second to impart to t e wings an inherent self-adjusting action to keep the lifting force constant during flight through turbulent air. This is attained by hinging the Wings to the fuselage by means of joists projecting forwardly from the wings, whereby the angle of attack increases when the airfoil swings downward and decreases when the latter s'wings upward.
Another object is attained by providing a retarding damper to check the vibration of the airfoil.
It is well known that carrying planes in oscillating air or during flying through wind billows are subjected to sudden changes in lift thus causing a dangerous strain on the wing structures, and making travelling very uncomfortable. Especially 1n trans-Atlantic flights, where air sinks ,were experienced some of which may have been the cause of disasters of heavily loaded planes, it will be of great advantage to have means for absorbing the above-mentioned shocks, thus makin flying independent of the weather, and w on fi mg throu h wind billows the automatic a justment o the angle of attack will prevent sudden dropping of the airplane.
An airplane equipped with my invention will be able to alight on a rough field because the shocks incurred will be counteracted by the increased lift and drag acting on the carrying plane which swings downward during a s ock, thereby opposing the tendency to tilt over.
Other objects will appear in the following detailed description and the accompanying drawings wherein:
Fig. 1 is a vertical section on the longitudinal axis of the airplane equipped with m invention.
ig; 2 is a top plan view of the middle portion of said airp ane.
'The terms employed herein are used in the generic and descriptive sense and therefore are not intended primarily as terms hinges 4 formed on or secured to the fuselage 2. The double arm hood 5 is fixed to the wing l and receives the elastic strands 6 associated with the fuselage 2 by means of the lever 7 pivoted to the upper portion of the fuselage 2 by a jaw hinge 8. The other end of the lever 7 forms aboss drilled and tapped to receive a thumb screw 9 for adjustment of the tension of the strands 6, to compensate, for instance, for fuel consumption or other changes in weight. The force exerted by the strands 6 is transmitted to the fuselage 2 and particularly to its longrons by the transverse strut 10 or any other suitable member of the fuselage, that shown on the drawings forming no part of the present invention.
The oscillation of the airalways tends to influence an airfoil during flight and if the airfoil is supported freely, a resonance effect occurs causing the excursions of the airfoil in the vertical direction to build up, imposing jerks and dangerous impulsive loads on the airfoil. This is eliminated in my 1nvention by providing a retarding damper which absorbs all vibrations without disturbing the excursions of the airfoil that are concurrent with the fluctuations of the wind. 11 constitutes the cylinderof the damper and is rigidly secured to the fuselage 2 by the flange 18. The plunger 13 at its lower end 14 is adapted to slide in the cylinder 11, and is also guided at 15, the upper end 16 havlng the shape of a T whose arms are held in the slotted lugs 17 secured to the airfoil 1. The cylinder 11 may be half filled with oil or any other suitable retarding medium which has to ass through the small space between the cylinder wall and the head 14 when the latter is moving up or down, thereby dampi ng the motion of the lunger and the elements connected therewlth.
The excursions of the wing from its normal position are limited upward, by the stop 12, and downward, by the bottom of the cylinder 11, by stopping the head 14 of the plunger 13.
The damper as shown on the drawings may be of any standard kind and the details shown are only illustrative and form no part of the present invention. V
The operation of the invention will -be briefly stated: a
The strands 6 are rigged so, that the air foil, when in undisturbed flight through quiescent air, attains an angle of attack that is known to be most economical. N ow suppose a sudden upward current is encountered. The increased lift presses the airfoil upward until it attains the angle of attack where the tension of the elastic strands .balances the lift, therefore the angle of wing setting and consequentl the drag component are now smaller. T e result is that the force of upward currents augments both lift and thrust instantly without imposing any disturbing shocks on the airplane.
. If the airfoil is projected through air sinks, it is prevented from sudden dro ping, because thestrands contract as the li' ing force decreases, thereby the airfoil attains a steeper angle of attack and the liftis compensated.
In the embodiment shown herein, rubber strands of the kind used for shock absorbers on landing gears are employed to obtain a featherin action between the wing and the fuselage; owever, any other elastic medium may be used, such as steel or pneumatic sprmgs.
. It may readily be seen inspection of the b drawings that the drag of the airfoil produces .a torque about the pivotal axis in cooperation with the elastic strands 6. This torque 1s dependent on the distance between the pivots .cient to keep the airfoilat the desired pitch so that the springs 6 may be dis ensed with. However, in the preferred em odiment of m 'inven'tion, I have selected a combinationof the two described principles, whereby the itchingmoment necessary to maintain the esired angle of incidence is effected by both the elastic strands and the torque due to the drag." This arrangement permits the airfoilto make excursions upward and downward whenflying througherratic wind and makes the whole system very elastic, especially .when landing and alighting.
The embodiment ofmy invention shown in this application pertains only to one type of aircraft and. may be changed for other of the leading ed e of the airfoil.
'9. In combination, airplane body, a "180 types without departing from the broad scope of the invention.
Further embodiments, modifications and variations may be resorted to within the spirit and scope of the invention as here claimed.
I claim: a
1. In an airplane, in combination, a fuse lage, an airfoil, means for connecting said airfoil to a transverse ivotal axis that is in' fixed relation to the uselage' and substantially in advance of the airfoil, elastic means associating with the fuselage and the said airfoil and tending to increase the angle of. incidence of the latter, means for adjustment of the tension of the elastic members, and a damper interposed between the fuselage and the airfoil to prevent vibration of the latter.
2. In an air lane,,in combination, a fuselage, 'an airfoi means for connectiong said airfoil to a transverse pivotal axis that is in advance of and below the said airfoil, elastic means associating with the airfoil and the fuselage, said elastic means opposing the. .weight of the latter and tending to increase the angle of incidence of the said airfoil,
means for adjustment of the tension of the elastic members, and means for retarding the excursions of the airfoil from the normal position to prevent vibration 3. In an airplane, in combination, a fuselage, an airfoil above said fuselage, and means for pivot-ally connecting the airfoil directly-to the fuselage at a point forwardly 4. In an 'airp ane having a fuselage, a wing, means for connecting said wing for bodily movement with respect to the fuselage, and means normally'tending to increase the angle of incidence of said wlng'.
5. In an airplane having a fusela e, a wing, means for connecting sald wing or bodily movement in a vertical plane withrespect to .the fuselage, and means normally tending to increase the angle of incidence of said wing. 6. In combination with a fuselage, an airfoil, and means for pivotally mounting said airfoil with respect to the fusela e, said damping meansconnecting means being arranged forwardly of t e'lead-' 1 lage, an airfoil, means for pivotally connect- 1 ing the airfoil to thefuselage at apoint forwardly of the leadingedge of the airfoil, and damplng means interconnecting said airfoil and fuselage.
ism 3 wing disposed transversely of said bod means for connectin said wing forwar y of the leading edge t ereof to said body for bodily movement in a vertical plane with re- 5 spect to the latter, and means for yieldably retarding such bodily movement.
10. In combination, an airplane body, a transverse wing, means for connecting the body forwardly of the leading ed e of the wing to the latter adjacent the lea ing edge for bodily movement, and dampin means associated with the .wing and b0 y, said means including means for positively limiting the bodily movement of the wing.
In testimony whereof I have signed this specification.