Jubilee - Radio control aerobatic slope soarer for 2 functions.
Quote: - "ON THE glider pages of the journals we often see pictures of smiling experts casually displaying models that have performed faultlessly for hours on end. Earnest, competent lads who hurl their magnificant machines out into space from awe-inspiring slopes, and do precision manoeuvres with casual ease, in idyllic conditions.
Now, I may be unfortunate - or perhaps I have annoyed some ancient Celtic god who looked after hill forts before the National Trust took over - but rarely do I get conditions like the aforementioned fliers enjoy. In the beginning, there was always the 'wrong model' situation. I would drive many leagues, struggle up some first cousin to Everest and, on cresting the ridge, the 30 knot breeze would immediately die to a zephyr - rendering the symmetrical sectioned javelin I had hauled up there as much use as a bucket of wet sand. Alternatively the 12ft. symphony of structural delight would be torn from my nerveless grasp by an unforecast local hurricane. I did get bored with it - and so did my poor wife - 'I've brought the wrong model' - and she would tremble and shed a little sigh and kick the dog.
I eventually reacted to this state of affairs by making a model that was very light with a semi-symmetrical aerofoil (Eppler 374) and a ballast box for windy weather. It also had provision to droop ailerons for lift scratching. I did a lot of cut and try with this model experimenting with tailplane sizes, control move-ments, rigging angles and CG positions. It led me back to the conclusion that - for all round flying (not competitions, which are not my kind of entertainment) simple and light was best. Suprise, suprise!
The outcome of all this was an aeroplane with a slim, flat-bottomed aerofoil, no gadgets and a simple, clean shape that I could make without complication. The weight was a minimum consistent with the realities of landing on nasty-shaped ground. I also experimented with wing-tip shapes because tip stalling can be a hazard with this sort of model. It had a ballast box originally but, since it proved capable of flying from a good slope in anything from 8 to 30 knots, ballast was never needed. Mine weighs almost 2lb giving a wing loading of about 10oz/sq ft. This explains the ability to fly in lower wind speeds, being a little low by slope soarer standards. Above all else, it is an easy model to fly in widely varying conditions and my 'wrong model' situation is now a much less frequent occurrence.
CONSTRUCTION Although this is quite simple and orthodox, a few notes are probably useful to read in conjunction with the drawing... "
Jubilee, Radio Modeller, June 1977.
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Article pages, thanks to RFJ.
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