US2120250A - Aerofoil - Google Patents

Description

June 14, 1938. HOUSTQN 2,12%,250

AEROFOIL Filed March 7, 1936 INVENTOR.

BY i 7 A TTORNEY Patna time i4, ices e'rer om Application March 7,

4 Claims.

This invention relates to aerofoil wings and in particular to wings which are used as lifting and sustaining surfaces for airplanes.

One of the objects of this invention is to pro- 5 duce an aeroioil wing which is adapted to alter the profile of the lower and upper wing surfaces, while flying, so as to obtain a radical variation in the aerodynamical characteristics of the aerofoil.

Still another object of this invention is to provide the aerofoil frames of an airplane with a thin flexible and air tight covering which is rigidly secured to the aeroioil frame structure at the front and rear edges.

Yet another object of this invention is to provide an aerofoil wing frame with a thin, flexible and air tight envelope and in which the profile thereof can be converted by altering the static pressure within said air tight envelope, so as to maintain therein selectively either a vacuum or a positive pressure.

Another object of this invention is to provide an aerofoil wing structure with a flexible and air tight envelope which,-when the interior as of the same is under vacuum, lies tightly against the profile of the frame structure, and when the interior of said air tight envelope is under positive pressure, the said envelope bulges and swells outwardly to a shape determined by the pres- ;0 sure against the inner surfaces and the limitations to movement imposed by its attachments at the front and rear edges of the aerofoil frame.

Still another object of the invention is to produce an aerofoil wing with a flexible and air tight covering. the profile of which can be selectively altered, while flying, in such a manner that the aerofoil profile, when under vacuum, assumes the shape which approximates that of an aeroioilgiving optimum values of high lift at low air speed, while, when the interior of the aerofoil wing is under positive pressure, the aerofoil profile approximates stream-line contour to allow maximum air speed .to produce the sustaining lift.

Since the wing profile, when under vacuum, is a section having optimum values of high lift at low air speed, this permits the aeroplane to be operated as a glider in the emergency of power failure, and vastly increases the range covered 50 by the gliding angle and powerless maneuverability, over present type of powered aeroplanes.

Yet another object of the invention is to produce an aerofoil wing provided with a flexible covering, the profile of which is selectively 55 changeable, while flying; so that by proper E936, Serial No. 6?,651

((91. Mil-44) manipulation (inflating and deflating)- deposits of ice or such other impediments precipitated upon the wing surfaces may be easily loosened and detached.

Other objects of the invention will become 5 apparent as the detailed description proceeds.

An illustrative embodiment in diagrammatic form of the invention is represented by way of an example in the accompanying drawing, wherein:-

Figure l is a sectional profile view of an aerofoil wing embodying my invention, the aerofoil envelope having a U-shaped nose or leading edge and being shown when under internal positive pressure.

Figure 2 is a fragmentary top elevation of an aerofoil wing in diagramatic form as used in my invention, the frame structure being partly exposed.

Figure 3 is a sectional profile view of an aerofoil wing as shown in Figure 1 showing the flexible covering or envelope under internal vacuum.

Figure 4 is a sectional view through one of the ribs of the frame structure on line 8-4 in Figure 3.

Figure 5 is a sectional view through one of the ribs of the frame structure on line 55 in Figure 1.

Figure 6 is an enlarged fragmentary side elevation of a rounded nose on the leading edge of the 3-3- aercfoil. I

Referring to the drawing, the aerofoii wing embodying the invention comprises a frame structure lt,.strong enough to not only maintain the proper acre-dynamic form of the aerofoil, but also to transmit the air pressure and lift to the body of the machine. Since it is thought that there is no novelty involved in the construction of the said frame structure as used in this invention, a detailed construction thereof is there-\ fore not shown.

In general, the said frame structure comprises a series of parallelly disposed ribs Ii, curved to the aerofoil form, as shown, and usually joined by crosswisely disposed spars l2. The nose H of i5 ribs H is rounded, as shown.

The aerofoil profile is of a usual type, with a concave undersurface which terminates into a thinned-out trailing edge Hi, and to reduce the weight of the ribs Ii, openings l5 are provided, since lightness is a primary consideration.

The leading edge l6 of the wing structure is provided with a U-shaped nose l1 made of any suitable material, which fits over the nose I3 of the ribs II, and the trailing edge it may also be provided with a U-shaped nose It, or if lage as cantilevers in a usual manner (not.

shown) and care must be taken that the envelope or covering I9 maintains its air tightness around any bracing. As additional accessories anair compressor, a vacuum pump, valves and pipe connections are required when using an airplane equipped with my improved aerofoil wings.

The aforementioned accessories have not been detailed or shown for the reason that. the various features of this invention will be clear with-' out further elaboration of describing well known parts and its connections.

Heretofore, aerofoil wings for airplanes were generally designed to fulfill only one condition, for instance, one capable of high lift at low air speed, or a high speed for sustaining lift, but with my improved aerofoil wings a combination of both conditions maybe easily obtained.

The operation of an airplane embodying my invention is as follows:'

Assuming, that manually operated valves from the vacuum pump and the air compressor are conveniently located near the pilot's seat and that a pipe from the same enters the interior of each wing at the body end 20. It is suggested,

- in order to avoid too many openings in the flexible envelope or covering I 9 'to permit only one pipe 2|, to enter each wing. This is usually done by connecting the pipes coming from the vacuum pump and the compressor by means of a suitable fiap valve (not shown) so that a single pipe will serve as a vacuum and compressor inlet pipe.

Before rising, the pilot opens the vacuum pump valve by means, of which the air in the interior of the wing] envelope will be sucked out thus creating a vacuum within the hermetically sealed flexible envelope l9 and thereby forcing the said covering to lie tightly against the frame work of the aerofoil wing which then takes up a profile section determined by the design of the framework, as, for instance, illustrated in Figure 3. In this condition, the aerofoil wings are no)? adapted for high'lift at low air speed.

After the airplane has reached a sufiicient height, the pilot opens the compressor valve, by means of which air is rapidly pumped into the hermetically sealed flexible envelope l9 and the same bulges and swells outwardly to a shape determined by the internal pressure against the inner surfaces and the limitations to movement imposed by its rigid attachments at the leading edge l6 and the trailing edge ll. of the aerofoil wing and by other attachments to the wing frame also, if desired. In this condition, the aerofoil wings are adaptedfor maximum air speed to produce the sustaining lift. a

When desiring to land or cruise at low speed in the air, the pilot again adjusts the aerofoil wing interior to the vacuum condition to change the wing profile to the high lift and low speed type.

As will'be'miderstood, there ma be slight changes made in the construction and arrange ment ofthe details of my invention without departing from the field and scope of the same and I intend to in lude all such variations, as fall within the scope of the appended claims.

I claim:

1. An airfoil comprising an, inner supporting framework, theperimeter of which is surrounded by an aerodynamical surface consisting 'of=anhermetically" sealed, continuous envelope "of metal sheet, flexible due to its thinness, and partly secured to said framework, the unsecured portions of said envelope being movable in response to either a positive or negative static pressure respectively against the inner surfaces of said hermetically sealed envelope, thus altering the aerodynamical profile of the airfoil.

2. An. airfoil comprising an inner supporting framework, the perimeter of which is surrounded by an aerodynamical surface, said surface consisting of an airtight continuous envelope of metal sheet, flexible due to its thinness and secured to the underlying framework only at the leading edge and trailing edge, the unsecured portions of said envelope being movable to either of two stable positions by maintaining selectively a positive or negative static pressure within said airtight continuous envelope, thus altering'the aerodynamical profile of the airfoil. 3. An aeronautical membercomprising an underlying frame structure, an airtight flexible continuous envelope of metal sheet surrounding the perimeter of said member, said envelope forming the aerodynamic surfaces of said member and partly secured to said member, and means to maintain the static pressure within said airtight flexible envelope at either a positive or negative value with respect to the outside atmosphere.

4..A wing for aeroplanes, comprising an underlying frame structure of airfoil profile section,

an aerodynamic surface formed by an airtight flexible continuous envelope of metal sheet having a perimeter substantially equal to the perimeter of the underlying frame profile section, said envelope surrounding the perimeter of said frame structure and rigidly attached thereto only at the leading edge and trailing edge, and means to selectively maintain either a positive or negative static pressure against the unsecured inner surfaces of said airtight flexible envelope.

CLAUDE M. HOUSTON.

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