Increasing G absorbance of seat mounts

I recently posted some thoughts on a stall resistant wing. Along with that, I have a few other thoughts on small aircraft safety issues I'd like to develop (none of this is for high performance craft; if I could, I'd like to design a small plane to be the equivalent of the family car in terms of price, ease of use and safety):

(1) increasing fire resistance of fuel tanks for light aircraft
(my thoughts are along the lines of having the tank enclosed in a shell filled with foam, with the idea that anything that penetrates the fuel tank also penetrates the foam shell, thus resulting in foam automatically being there; unfortunately, I haven't worked out a solution for gravity draining the foam away from the puncture [maybe a pressurised foam shell?], and I don't know if the quantities of foam required would be too heavy);

(2) improving the G absorbing properties of seat mounts.

This post has now been developed to cover the second of these ideas, which is based on the notion of providing attachment points filled with small spheres of varying size and flexibility. The smaller spheres have a larger surface area, but less travel: combined with a more flexible material, perhaps these could be used to absorb G forces for lighter people. The larger spheres have potential for a greater distance of travel: perhaps this could be combined with a firmer material to allow absorbance of G forces for heavier passengers?

Look at the following notes and sketches.


























Kayleen

Tags: G forces, seats, passengers, accidents, restraint

First published: Tuesday 3rd June, 2008
Last edited: Monday 12th January, 2009

Towards a stall resistant wing

A few years ago, there were problems with aviation fuel which led to several crashes of light aircraft. Around that time I started wondering if it would be possible to design a wing profile which was somehow able to AUTOMATICALLY convert itself to a parachute for situations where power was lost and, for some reason, the aircraft's pilot wasn't able to glide.

My initial thoughts were along the lines of hollow sections with a scoop at the leading edge, or a flexible fabric type wing where a drogue would change position and allow a change of shape with a change of pressure (these thoughts will become clearer after I am able to upload a few sketches), but I couldn't see any way they could be made practical for a typical light aircraft.

After some further thought, I had the idea of using a rotating section in the centre of the wing profile. The basic idea is that, while the wing has "normal", unstalled airflow around it, use the lift on the front of the centre third or so of the wing to hold up the rotating section; if the wing stalls, the changed airflow results in a loss of life, loss of pressure, and the rotating section opens up, changing the single airfoil into a tri-foil, with (1) the centre section having a different angle of attack owing to it's rotation, (2) the leading third having a altered angle of attack because of the way it is designed (see sketches when they're uploaded), and (3) the last third hopefully being able to take advantage of the altered flow off the leading two airfoils to be able to function. There is a bit of design detailing to balance weights, aerodynamic forces and positions of pivots (I suspect the pivot would have to be behind the centre of the rotating section, with some weighting in the aft section), but they're not insurmountable.

I see this having potential for problems in situations of turbulence, and the design would, of course, be completely unsuited for aerobatics. To some extent, I anticipate these problems could be overcome by having a hydraulic control system where the controls of the centre rotating third could be selected for the options of:
(a) locked open
(b) free to rotate (landing, take off and low level flight)
(c) locked closed (for normal flight at sufficient altitude for a change of control to be selected).

The mechanism of the rotating section would add to the weight of the craft.

I'll develop this idea and post with time, particularly with the addition of a few sketches. I had hoped to be able to do some wind tunnel/model testing, but things like family and day job commitments haven't allowed that.

Kayleen

Tags: aircraft, airfoils, aerodynamics, safety, flight

First published: Tuesday 3rd June, 2008
Last edited: Friday 11th July, 2008