GB2321888A - Inflatable flying canopy - Google Patents

Abstract

An aerodynamic canopy is defined by upper and lower sheets (1)(figure 2) and 2, supported by a framework and joined together to define an aerofoil shape, when free-stream air is admitted via a mouth 12, to the space defined between the sheets to inflate the canopy. The upper surface (1) is permeable whereby the pressure within the canopy can be controlled, and the air from within the canopy can be vented into the airflow over the upper sheet. A cord 11, acted upon by the weight of a pilot 9, can serve to draw the upper surface down to close off the airflow to the rear part of the canopy which then deflates leaving only a forward surface 6, inflated.

Description

FREE FLYING WING This invention relates to a free flying wing.

Considered opinion tells us negative drag is impossible to achieve. This is true of course. Drag forces continually absorb airspeed possessed by a glider :in liftless winds height must continually be sacrificed in order to maintain flight equilibrium,otherwise the machine would simply go into a series of stalls during its irrevocable return to earth.

However,under certain conditions,this situation may be reversed.

Where the airflow is non-steady known physical laws breakdown: nature's barriers become swept away - by the most simple means everything becomes possible within the low Reynolds number range,would man but utilise non-steady airflow. He needs only synthesize the headwind gust in continuum for him to accomplish free migratory flight.

Dual-flight configuration provides a means for rapidly reducing,and then increasing again the flying speed of a glider without recourse to change in attitude to the relative airflow.

Dual-flight configuration has great significance for man. It provides a means for him to enlist the assistance of mother nature herself in his efforts to perform free flight - and help she does in providing means for the generation of energy inputs,equivalent in every way to those produced by wing flapping - except in our case wings are rigidly held.

For brevity,let us call one such energy input a 'freebie.' Freebies are enabled because of the time-lag that exists between the generation of aerodynamic lift and the onset of drag. By way of working within said time-lag a freebie may be generated at any time during normal flight,without extra drag penalty being so incurred and, if one freebie might be generated then so can any number by these same means.

However it is an essential requirement that these manoeuvres be peformed in a rapid-action manner,and cleanly if they are to provide maximum benefit.

Indeed,this is the key to our successfully employing a relatvely small amount of pilot energy to task of generating an energy sufficient to fuel extended gliding flight in liftess winds.

The closer an efficient airfoil is held to the relative airflow then further extended does time-lag become. But if we employ high-lift devices,so as to further extend time-lag duration, then the value of any freebie so generated might be increased proportionately:reducing pilot fatigue in the long term because fewer freebies than before would be required in order to sustain flight.

If we take the example : The pilot of a dual flight configuration glder,flying at 30mph say,suddenly puts his machine into its lower flying speed mode of 15mph. There would immediately be created 15mph's worth of surplus airflow. This surplus airflow would in its turn just as rapidly become converted into extra aerodynamic lift.

It would be just as though the glider had met a sudden and sharp gust of wind,head-on - this situation satisfies our requirements.

Four important facts must now be considered.

First then,the machine would continue travelling through the air,at its airspeed of 30mph,for a second at least.

Nothing is changed,save for a small increase in the wetted area of the wing.

Secondly the extra aerodynamic lift generated might be sufficient for the machine to climb at a rate of lOft per second,ie,a height gain of ten feet per freebie might be made.

Thirdly,because extra lift becomes generated without recourse to raising the nose of the machine,wetted area remains unchanged;little or no extra drag penalty would be incurred.

And finally,should the pilot with some urgency revert the machine back into high speed flight mode,before extra drag penalty has time to make itself felt,then the glider would proceed once more along its glide path;but from a higher altitude than before and without loss of momentum.

From what has gone before such an aerodyne might accomplish free flight take-off from a point of low elevation,on condition glider flying speed could be reduced to match man's running speed.

The vented canopy airfoil is a suitable vehicle to this purpose. It being required only to inflate same by the force of the free airstream for it to adopt its airfoil shape.

Efficient venting serving to prevent excessive build-up of dynamic pressure within said canopy.

The vented canopy providing also a means for sail deflation.

Sail deflation may be accomplished by the simple process of cutting-off the flow of free airstream to the inflatable airfoil. A pilot body weight cotrolled air valve is ideal to this task for the force of the free airstream may be employed,counter-balance fashion in forcing same open,so aiding the pilot in this task.

It will be seen that by expelling a mass of free airstream out through strategically placed outlets located about the "downhill" side of the canopy,to mix with and speed up the laminar flow there,then three birds become killed with the one stone.

First then,dynamic pressure within the canopy may be reduced to the minimum by this means.

Secondly,the static pressure above the wing is consequently reduced as a result of subsequent speeding up of the laminar flow.

Thirdly,by expelling the free airstream from within the canopy directly into the laminar flow at strategic points airflow separation might possibly be delayed.

And we can improve on this.

Because we are able to efficiently vent the canopy we are within reason,at liberty to cram into the canopy as much of the free airstream as we are able - the more air we shove in then the more air we may expel into the laminar flow,so further reducing static pressure there.

In proceeding along these lines we see there is yet another benefit to be gained by employing the vented canopy in the afforesaid manner,ie,static pressure differential above and below the wing becomes compounded.

If we go back to the idealised example of a dual flight configuration glider we see that its higher flying speed is 30mph.

During its flight at 30mph there would be a static pressure differential equivalent to this speed both above and below the wing.

However,at time of change down into its low flying speed mode of 15mph the static pressure above the wing becomes greatly reduced,whereas static pressure below the wing remains totally unaffected during said time-lag period.

Above the wing,apart from there now being a general speeding up of the airflow on account of its having to travel further over a more volumous airfoil,there would be a further speeding up of laminar flow-rate by way of the huge volume of air now escaping from within the airfoil,as before described.

By this means then the static pressure above the wing could possibly be reduced to an airspeed equivalence of 40mph. It would be as though the wing were travelling through the air at 40mph,so that in effect a static pressure equivalence to 30mph below the wing would probably be acting upon a static pressure equivalence to 40mph above the wing:a wing,incidentally,which now has a flying speed of only 15mph.

Claims that the static pressure differential above and below the wing becomes compounded on two counts during time of change down to lower flying speed are now shown to have substance.

According to the present invention there is provided two sheets,an upper sheet which is supported by a framework so as to billow upwardly thereof,and a lower sheet also supported by the framework beneath at least a part of upper sheet and the two being joined together save for one or more loose sections,central or thereabouts at its front end,and said loose sections serving as air inlet for free airstream to purpose of canopy inflation and upper sheet being air permeable sufficient at least to efficiently vent air from within inflated canopy,out into the laminar flow,and at the same time by this means reduce dynamic pressure within inflated canopoy.

A specific embodiment of the invention will now be described by way of example with reference to the accompnying drawing in which: Figure 1 shows in perspective underside view of aerodyne.

(framework not shown) (elevator not shown) Figure 2 shows front view of aerodyne.

Figure 3 shows cross-sectional view of aerodyne through keel with canopy deflated. (framework not shown) (elevator not shown) Figure 4 shows cross-sectional view of aerodyne through keel with canopy inflated. (framework not shown) (elevator not shown) Referring to the drawing the wing comprises two sheets,an upper billow sheet 1 and a lower sheet 2, both supported by a framework (not shown). Sheet 1 and sheet 2 being joined together at or near the perimeter of sheet 2 save for one or more loose sections 3.

Air permeable windows 4 allow the force of the free airstream 5 entry therein. Force of free airstream 5 through windows 4 serve help inflate both canard surface 6,and airfoil 8.

Freely suspended pilot body weight,hereinafter named the load, 9 in acting upon control cord 11 serves to close airvalve 10.

Upper billow sheet 1 rearwards displaced of canard surface 6 and airvalve 10 forming simple cambered airfoil 7 during deflation of airfoil 8.

Open mouth 12 serving to allow full force of free airstream 5 strike both under surface of canard 6 and airvalve 10 during flight. Free airstream 5 in effect striving to force open airvalve 10 against load 9 bearing down upon valve 10,so as to apply a counter-balance between two opposing forces during flight. Load 9,doing a press-up on bottom bar of glider control frame automatically removes load 9 from airvalve 10.

Claims (3)

1. Two sheets,an upper sheet which is supported by a framework so as to billow upwardly thereof,and a lower sheet also supported by the framework at least a part of upper sheet and the two being joined together about the perimeter of lower sheet save for one or more loose sections,central or thereabouts at the front end,and said loose sections serving as air inlet for free airstream to purpose of canopy inflation thereby and upper sheet being air permeable sufficient at least to efficiently vent air from within inflated canopy,out into the laminar flow,and at the same time by this means reduce dynamic pressure within inflated canopy.

2. Two sheets as claimed in claim 1 wherein upper billow sheet may be deflected downwardly under force of freely suspended pilot body weight so as to close off airvalve,thereby providing means for canopy deflation.

3. An aerodyne,as claimed in claim 1, substantially as hereinberfore described with reference to figures 1-4 of the accompanying drawings.

3. Two sheets as claimed in claim 1 or claim 2 wherein upper billow sheet is provided a degree of permeability sufficient to maintain a low state of dynamic pressure within inflated canopy.

4. Two sheets as claimed in claim 2 or claim 3 wherein a canard surface is provided during time of canopy defalation.

5. Two sheets as claimed in claim 4 wherein air permeable windows are let into leading edge of airfoil.

6. Two sheets substantially as described herein with reference to figs 1-4 of the accompanying drawing.

Amendments to the claims have been filed as follows CLAIMS 1. An aerodyne comprising an inflatable canopy defined by an upper sheet and a lower sheet supported by a framework, said upper sheet being capable of billowing upwardly thereof, said lower sheet extending beneath a rearward portion of said upper sheet and having a leading edge spaced rearwardly of the leading edge of said upper sheet,the upper sheet being joined to the lower sheet around the entire periphery of said lower sheet save for one or more portions of said leading edge of said lower sheet, whereby an unjoined portion of said leading edge of said lower sheet and an adjacent portion of said upper sheet define a closable inlet for admitting airflow into a chamber defined rearwardly of said inlet between said lower sheet and said upper sheet, to inflate said chamber, means being provided to enable, in flight, the weight ofSO,t~ to be transmitted to said adjacent portion of said upper sheet above said unjoined portion of said leading edge of said lower sheet, whereby to draw said upper sheet down towards said leadi'ng edge to close said closable inlet, or to enable the pilot to relieve said portion of said upper sheet from said weight of said pilot, thereby enabling air pressure to open said inlet, said upper sheet being permeable to allow air from the inflated portions of the aerodyne to flow into the airflow over the upper surface of said upper sheet, the arrangement being such that when said inlet is closed said chamber deflates, whereby said canopy comprises an inflated portion defined by said upper sheet forwardly of said inlet and a deflated portion rearwardly of said inlet, and when said inlet is open said chamber inflates to define with said inflated forward portion an inflated canopy extending forwardly and rearwardly of said inlet.

2. An aerodyne as claimed in claim 1 wherein air permeable windows are provided in the leading edge of said canopy.