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- Senior Member
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I don't remember any specific discussions on this forum. The best reference/resource for backgliders is probably Robert Youen's pages describing his "coney" rocket.
He gives the breakdown on what to change to move one or more of the rocket stability control points (the centre of gravity, centre of pressure & centre of lateral area) until you get the configuration most likely to pull the rocket into backgliding mode on descent.
I don't have it down to an exact science. Using a standard 1L bottle with extra fairings above it made from straight sections, I get around 2.5 x the original height which is about 8 x the calibre/bottle diameter (I think the recommended length is at least 10 x calibre, and yes: sometimes my rockets fail to backglide). Using smallish light fins (made from light card) as far back as possible plus a very small (5g) plastic top on the tip of the nosecone, I can get the correct order (from nosecone: CLA then CG then CP, ideally separated by 1 calibre). Usually without having to add surplus weight, but a little extra at the nose can be needed.
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We did backsliding rockets a while back. We had hoped that perfecting the backslider that we would gain an advantage in setting a world altitude record contest by avoiding the extra weight and complexity of a recovery system.rocketb wrote:Hi: I just joined the forum. Am interested in bottle rockets without parachutes or any other mechanisms to deploy on way down. Does anyone know what is already here in the forum on such back sliders?
What we discovered was that backsliders were sensitive to changing wind conditions and would easily nosedive if the wind shifted. This became a big problem because the winds often move in different directions at different altitudes, so a very high flight will descend through several layers of wind and each one increases the chances of causing a nosedive. We abandoned the idea and worked on a lightweight deploy system instead.