GB2231316A

GB2231316A - Flexible lightweight aerofoil sheath for hang-glider and micro-light "uprights" and king posts

Info

Publication number: GB2231316A
Application number: GB8910160A
Authority: GB
Inventors: Christopher John Gladish; Brian Henry Wilton
Original assignee: Individual
Current assignee: Individual
Priority date: 1989-05-03
Filing date: 1989-05-03
Publication date: 1990-11-14
Anticipated expiration: 2009-05-03
Also published as: GB2231316B; GB8910160D0

Abstract

The flexible aerofoil sheath 1 in suitable high impact plastic material can be mounted on a metal inner strength tube 2 and can incorporate an internal web (5) (Fig 4) or other means 6 of location in relation to the inner tube 2 which will enable detection of any permanent deformation in the inner tube in the event of impact thus incorporating an important safety feature in this invention. The flexible outer sheath 1 can be removed and fitted onto a replacement inner-tube 2 in the event of damage to the latter. The sheath can be adapted to suit the majority of end fittings on hang-gliders' and micro-lights' control frame uprights currently in use. By virtue of retention of an inner strength tube of correct material and dimensions a lightweight aerofoil sheath can be utilised. This principle can also be applied to king post construction. The space between the sheath 1 and tube 2 can be filled with light-weight foam 3. <IMAGE>

Description

FLEXIBLE LIGHTWEIGHT AEROFOIL SHEATH FOR HANG-GLEDERS AND MICRO-LIGHT 'UPRIGHTS' AND KINGPOSTS This invention relates to a universally applicable flexible aerofoil sheath for fitting to the control frame uprights of hang-gliders and micro-light aircraft and/or to the kingposts of such aircraft.

The uprights referred to in paragraph one are components which are necessary in prevailing design of hang-gliders and many micro-light aircraft from the points of view of structure and fo control. They are frequently made either from aluminium alloy extrusions with an outer aerofoil cross-section, which may or may not require an inner reinforcement tube of circular cross-section, or from an inner strength tube with a separate outer aerofoil tube of aluminium alloy. Each of these methods of manufacture results in an expensive component which by nature of the material used is prone to impact damage requiring replacement of the whole component, the damage occurring usually upon heavy landings or during ground handling in gusty or turbulent conditions.Many of the aforementioned aircraft are still fitted only with uprights and kingposts of circular cross-section, and the performance of these aircraft would be improved by means of easy and lightweight conversion of these components to an aerofoil cross-section, by the fitting of a flexible lightweight sheath which is, however,rigid enough to be self supporting during flight and ground handling.

This invention provides a self-supporting butflexible high impact plastic aerofoil sheath fitted over an inner strength providing tube and with appropriate end fittings. The composite unit of the invention can be adapted to suit the majority of end fittings currently in use on uprights and king-posts, to provide an economical and lightweight replacement for the rigid metal uprights currently in use. The sheath as such may provide conversion for existing circular cross-section components in use to a composite aerofoil /cross-section...

cross section unit according to the invention. This invention could also be incorporated in future new designs or in modifications to existing designs.

Two important aspects of this invention are that (1) under some circumstances damage, requiring replacement may be limited to either the plastic outer sheath itself, or only to the inner strength tube - in which case only one of these items would need to be replaced, and (2) that by reference to the outer sheath, any significant deformation of the inner strength tube relative thereto can be detected and further checking and/or replacement of this latter strength item can then be carried out.

The accompanying drawings show several examples of configurations proposed in accordance with the invention. Each of figures 1 to 6 is a cross-section through an upright or kingpost according to the invention.

Figure 1 shows a flexible aerofoil sheath 1 comprising a 'high-impact' plastic material, for example polypropylene or PVC, extrusion sized to suit the dimensions of an inner circular section strength imparting tube 2.

Tube 2 may be as currently in use, and the sheath 1 is fitted over the inner tube 2.

The flexibility of the sheath 1 allows variations of dimensions of the inner strength tubes 2.

The material used for the sheath should not be adversely affected by the extremes of ambient temperature which could be expected in use.

As noted above, the sheath 1 may allow detection of inner tube 2 deformation by means of reference to its own shape or appearance, e.g. by one or other of the following design features: - In-filling of the void spaces between the inner strength tube and the inside of the aerofoil sheath with a lightweight foam 3. This causes the aerofoil sheath 1 to follow any deflection of the inner tube 2, so if tube 2 deforms, the deformation is visible from the outside. The inner tube 2 would be treated with a suitable freeing agent to enable subsequent withdrawal from the foam 3.

- Fitting suitable 'spacer' sections 4 (see figs 3 and 4) within the void spaces has the same effect with respect to deflection.

- Alternatively incorporating in the aerofoil sheath extrusion 1 internal webs 5 (see figs 4 and 5) will cause the aerofoil sheath 1 to follow any deflection of the inner tube in at least one direction. An alternative is to incorporate in the aerofoil sheath extrusion internal webs 5 or variations in shape 6 (figure 6) which will upon deflection indicate on the outside of the aerofoil sheath a 'stress' mark. The appearance of such marks may be a characteristic of the specific type of material chosen for the extrusion.

- Yet a further alternative is to provide a small 'sighting' hole in the aerofoil sheath 1 through which a reference mark on the inner strength tube 2 can be seen, and which will allow any permanent misalignment to be detected.

The sheath 1 can be made in a variety of colours and can be adapted to suit a variety of end fittings. If desired the sheath 1 can be precisely located on the inner strength tube 2 by means of rivets or bolts or screws.

Claims

Patent Application No.8910160.

FLEXIBLE LIGHTWEIGHT AEROFOIL SHEATH for HANG-GLIDERS andMICRO-LIGHT 'UPRIGHTS'and KINGPûSTS.

CLAIMS 1 The self supporting but flexible high impact plastic aerofoil sheath 1 is attached precisely to an inner strength providing tube 2 and with appropriate end fittings to form a composite unit.
2 The sheath 1 as claimed in Claim 1 will allow detection of inner tube deformation by means of reference to its own shape or appearance for example by one or other of the following design features: a in-filling of the void spaces between the inner strength tube and the inside of the aerofoil sheath 1 with a lightweight foam 3 therefore causing the aerofoil to follow any deflection of the inner tube 2,the inner tube 2 would be treated with a freeing agent as neccessary to enable subsequent withdrawal from the foam
3.

b fitting of suitable 'spacer' sections 4 (see figs.2 and 3) within the void spaces thus having the same effect with respect to deflection.

c incorporating the aerofoil sheath extrusion 1 internal webs 5(see figs4 and 5) which will cause the aerofoil sheath 1 to follow any deflection of the inner tube 2 in at least one direction.

d incorporating the aerofoil sheath extrusion 1 internal webs 5 or variations in shape 6 which will upon deflection indicate on the outside of the aerofoil sheath 1 a'stress'mark which is a charact eristic of the material chosen for the extrusion.

e a small 'sighting' hole in the aerofoil sheath 1 with a reference mark on the inner tube 2 which will allow any permanent misalignment to be detected.