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Don Cooper
01-29-2003, 11:06 AM
My son recently gave me a kit for a foam ARF glider (called the Double Eagle) he found while cleaning his attic. He said it had been there for at least 15 years. I had an IPS 'A' motor laying around, so I mounted a stick in the gliders nose and stuck the motor on. The glider has a 50" span, and out of the box weighed about 17 oz complete, including motor, battery, and electronics. In order to get a climb under power, and a decent unpowered glide angle, it had to fly right on the verge of stalling. The foam is pretty dense and heavy by today's standards, so I decided to drill it full of holes and cover it with Reynolds Wrap. I hoped to lighten it enough that the best climb and glide angles of attack would move down from the stall angle a little. It now weighs a little less than 12 oz. However, it still seems to fly best very close to the stall AOA, close enough that a gust will often cause it to stall. This is my first glider - is that characteristic of gliders? If not, is there anything I should try to reduce the best flight angles relative to the stall angle? The horizontal tail moves as one piece, i.e., there is no separate elevator surface, so there shouldn't be a decalage problem.

Dave Robelen
01-29-2003, 11:55 AM
Hello Don,
It sounds like you have gotten hold of a slope soaring glider. A 16 (or 12) oz model with a span of 50", and a normal wing chord, will need to fly rather fast for good control. The GWS IPS series power units are getting near their limits at about 7 oz. It sounds like you are trimming the model to try and accomodate an underpowered condition. In general, gliders do quite well when trimmed for flight below the stall, but almost any model that is trimmed that close to the critical angle is going to be tricky.
Regards, Dave

Don Cooper
01-29-2003, 04:14 PM
Dave,
Thanks for the quick response. I have done some more experimenting and found that at the lighter weight, with an S2 motor with 8-6 prop and enough patience I can get it high enough without stalling for some floating around, which is what I wanted it for. Glide ratio is mediocre at best, but it doesn't take much power to maintain altitude, so that with a combination of gliding and low power cruising I can get around 15-minute flights using a 7 - cell 250 mah Nicad.