GB2141985A - A propulsion unit for an aircraft - Google Patents

Abstract

This invention relates to a propulsion unit (10) of an aircraft the unit (10) comprises a frame (11) on which is slung a pilot support (12). The frame has a retractable undercarriage (13) mounted thereon and provides a mounting (14) for a hang-glider wing. The support (12) comprises a cocoon (12a) which is attached to the frame (11) so that a pilot can pivot from a semi-vertical entry position into a horizontal flight position, the pilot lying prone in the cocoon. An engine (15) is mounted in the rear of the cocoon (12a) and fuel tanks (33) are mounted one on either side of the pilot. <IMAGE>

Description

SPECIFICATION A propulsion unit for an aircraft This invention relates to propulsion units for aircraft, and in particular, but not exclusively, to aircraft having hang-glider wings.

Over the last ten or twelve years the sport of hang-gliding has become very popular. As this sport is dependent on the right wind conditions, if a glide is to be maintained, various proposals have been made for adding power units to such gliders to assist in sustaining a glide. Simultaneously the increasing popularity of private flying and its ever escalating expense had led to a new breed of aircraft called microlights. The big advantage of these aircraft, and indeed hang-gliders, is that until recently they have been subject to little or no restriction and no pilots licence was necessary. This position has now changed and any aircraft weighing more than 70-kilos requires certification by the Civil Aviation Authority and a pilots licence to fly it.

With present constructions of microlights it is very difficult to obtain an aircraft below this weight limit and so their main advantage has disappeared. powered hanggliders are not a replacement, because they cannot takeoff on the flat and hence can only be used at particular sites.

It is an object of the present invention to produce an improved propulsion unit for an aircraft which overcomes at least some of these problems.

From one aspect the invention consists in a propulsion unit for an aircraft comprising a frame, means for attaching a wing to the frame, a support for holding the pilot on the frame in a generally prone position and a power unit mounted on the frame in line with said prone position and rearwardly thereof.

In a preferred embodiment the direction of thrust of the power unit passes through the centre of mass of the propulsion unit or through the centre of mass of the propulsion unit and wing. The prone pilot lies along the line of thrust of power unit and is held balancedabout a vertical line passing through the centre of mass of the propulsion unit.

The support may be pivotally mounted on the frame to allow the pilot to pivot into and out of the prone position. This arrangement is particularly desirable when the frame is enclosed over at least the rearward part of the support. The support may be in the form of a couch or cocoon or the like to support the pilot along his length and may include a harness to retain the pilot on the unit.

Preferably the power unit is mounted to lie in the slip stream created by the pilot and/or the support.

The propulsion unit may have a retractable undercarriage, which may be telescopically connected to the frame and operated by a winch. The undercarriage may be threewheeled with a steerable rear wheel.

The unit may include fuel tanks mounted symetrically about a vertical line passing through the centre of mass of the propulsion unit.

From another aspect the invention consists in a propulsion unit for an aircraft having means for supporting a pilot in a generally prone position and a power unit disposed to lie in the slipstream created by the pilot and/or the support.

From a further aspect the invention consists in å propulsion unit for an aircraft having means for supporting a pilot to lie along the line of thrust of a power unit of the propulsion unit.

From a still further aspect the invention consists in a support for holding a pilot in a propulsion unit comprising a couch or cocoon and means for pivotally mounting the couch or cocoon or the like on the propulsion unit to allow a pilot on the support to pivot into and out of a prone position.

The invention also includes an aircraft comprising a wing and a propulsion unit as defined above. Preferably the wing is a hangglider wing and the aircraft is controlled by movement of the hangglider control bar.

The invention may be performed in various ways and a specific embodiment will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a diagramatic side view of a propulsion unit according to the invention; Figure 2 is a view from above (on a different scale) of the unit of Figure 1; and Figure 3 is a schematic side view showing the suspension of the pilot support of the unit of Figure 1 in more detail.

Figures 1 and 2 show a propulsion unit, generally indicated at 10, of an aircraft. The unit 10 has a frame 11 on which is slung a pilot support 1 2. A retractable undercarriage 1 3 is telescopically mounted on the bottom of the frame 11 whilst the top carries a mounting 14 for a hangglider wing. An engine, generally indicated at 15, is mounted to the rear of the frame and carries a propeller 1 6 on a short propshaft 17.

As can best be seen in Figure 3 the support 1 2 comprises a cocoon or couch 1 2a, which is open at its top, but which has side walls 1 8 which surround the pilot. The support is pivotally slung from upright members 1 9 of the frame 11 by means of a ring 20, suspended between the members 19, and ropes 21. The longitudinal movement of the support is limited by means of retaining straps 22 which are anchored to the upright members 1 9 of the frame 11. Harness straps 25 extend from the ring 20 to the front of the support 1 2.

The cocoon 1 2a is further attached to the frame 11 by means of a U-shaped tubular member 24 which surrounds the front of the cocoon and which is pivotally mounted on the frame 11 about a horizontal axis at 24a.

Preferably the U-shaped member 24 is bolted to the cocoon to hold it rigid during flight whilst allowing pivoting movement for the reasons explained below. The rearward upper part of the frame which surrounds the support is enclosed at 26, although the front of the support projects out of this enclosed portion.

The undercarriage 1 3 comprises a reverse tricycle arrangement with two front wheels 27 and a steerable rear wheel 28. The wheels are interconnected by struts 29 which are themselves telescopically mounted on the frame 11 by means of legs 30. The legs 30 are maintained in their lowered position by spring loaded bolts, which can be released by the pilot, in flight, when the undercarriage can then be lifted by a winch (not shown).

During taxiing the rear wheel can be controlled by the pilot by means of steering wires 31 which act on the pivotal mounting 32 of the rear wheel.

Fuel tanks 33 are mounted symmetrically about a vertical line passing through the centre of mass of the unit 10, so that as the fuel is used the balance of the unit is not affected.

In use the pilot enters the unit from underneath, whilst the support 1 2 is in its dottedline position. He passes his head between harness straps 25 and engages any other straps, for example a back strap, which may be thought desirable. He then places his legs into the rear portion of the support 1 2 and shifts his weight forwardly causing the support 12 to pivot upwardly into its horizontal position. Thus the pilot is held in a prone position in which he creates a very low drag and this is further reduced by the enclosure 26 which provides a smooth airflow surface.

The location of the engine 1 5 at the feet of the pilot also considerably reduces the drag over conventional designs, because it is then positioned in the slip-stream created by the pilot and the support. Further in this position the thrust of the engine passes directly through the centre of mass of the unit providing very efficient propulsion and removing any tendency of the propeller to rotate the unit.

The resultant efficiency and low drag characteristics of the propulsion unit enables a very small engine to be used and it is hence possible to build an aircraft having a weight well below the 70-kilos limit. Thus the novel configuration of the propulsion unit provides an aircraft which can take off from the flat and provide a sustained glide, but which does not require a pilots licence nor Civil Aviation Authority Certification.

Further it will be appreciated that the novel suspension of the pilot support from the frame enables the pilot to enter a prone position easily even when a major portion of the upper part of the craft is enclosed. Even more importantly the pilot can quickly pivot out of the prone position and slip out of the support in the event of a crash.

In addition to the single-man unit described above, it is envisaged that dual training units can be constructed, in which the instructor is either held in a further support 1 2 suspended above the pupil or is provided with a seat adjacent the pupil's head.

Claims (22)

1. A propulsion unit for an aircraft comprising a frame, means for attaching a wing to the frame, a support for holding the pilot on the frame in a generally prone position and a power unit mounted on the frame in line with said prone position and rearwardly thereof.

2. A unit as claimed in Claim 1, wherein the direction of thrust of the power unit passes through the centre of mass of the propulsion unit or through the centre of mass of the unit and wing.

3. A unit as claimed in Claim 1 or Claim 2 wherein the prone pilot lies along the line of thrust of the power unit.

4. A unit as claimed in any one of the preceding claims wherein the support holds the pilot balanced about a vertical line passing through the centre of mass of the propulsion unit.

5. A unit as claimed in any one of the preceding claims wherein the support is pivotally mounted on the frame to allow the pilot to pivot into and out of the prone position.

6. A unit as claimed in any one of the preceding claims wherein the frame is enclosed over at least the rearward part of the support.

7. A unit as claimed in any one of the preceding claims wherein the support is in the form of a couch or cocoon or the like to support the pilot along his length.

8. A unit as claimed in any one of the preceding claims wherein the support includes harness to retain the pilot on the unit.

9. A unit as claimed in any one of the preceding claims wherein the power unit is mounted to lie in the slip-stream created by the pilot and/or the support.

10. A unit as claimed in any one of the preceding claims including a retractable undercarriage.

11. A unit as claimed in Claim 10 wherein the undercarriage is telescopically connected to the frame.

1 2. A unit as claimed in Claim 11 wherein the undercarriage can be lifted by a winch.

13. A unit as claimed in any one of the preceding claims having a three-wheeled undercarriage.

14. A unit as claimed in Claim 1 3 wherein a rear wheel of the undercarriage is steerable.

1 5. A unit as claimed in any one of the preceding claims having a mass of less than 70 kilos.

16. A unit as claimed in any one of the preceding claims having fuel tanks mounted symmetrically about a vertical line passing through the centre of mass of the unit.

1 7. A propulsion unit for an aircraft having means for supporting a pilot in a generally prone position and a power unit disposed to lie in the slipstream created by the pilot and/or the support.

1 8. A propulsion unit for an aircraft having means for supporting a pilot to lie along the line of thrust of a power unit of the propulsion unit:

1 9. A support for holding a pilot in a propulsion unit comprising a couch or cocoon and means for pivotally mounting the couch or cocoon or the like on the propulsion unit to allow a pilot on the support to pivot into and out of a prone position.

20. A propulsion unit for an aircraft substantially as hereinbefore described with reference to the accompanying drawings.

21. An aircraft comprising a wing and a propulsion unit as claimed in any one of the preceding claims.

22. An aircraft as claimed in Claim 21 wherein the wing is a hang glider and the aircraft is controlled by movement of the hang glider control bar.