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Electric Airframes

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Dick Fowler:
Ron, I think we are in agreement in most respects.

Some thoughts on the "twitchy" problems when the nose MOI is reduced. Most of today's stuff has much larger stab/elevator areas when compared to the old designs. Probably helps overcome the fact that we now put more iron on the nose.

It might be interesting to move the batteries back on to the CG and reduce the area and or throw of both flaps and stab/elevator. With less mass up front, the required pitch forces needed to turn drop rather quickly. Wouldn't this still achieve good turn characteristics without creating as much induced drag.... hence the airspeed would not suffer as much on hard corners. Now before the purists jump on me and say that stall is a function of AOA and not speed, I would think a light plane with less MOI up front would fly through the corners as opposed to sink.

Ron King:

--- Quote from: Dick Fowler on August 17, 2006, 07:47:51 AM ---Ron, I think we are in agreement in most respects.

Some thoughts on the "twitchy" problems when the nose MOI is reduced. Most of today's stuff has much larger stab/elevator areas when compared to the old designs. Probably helps overcome the fact that we now put more iron on the nose.

It might be interesting to move the batteries back on to the CG and reduce the area and or throw of both flaps and stab/elevator. With less mass up front, the required pitch forces needed to turn drop rather quickly. Wouldn't this still achieve good turn characteristics without creating as much induced drag.... hence the airspeed would not suffer as much on hard corners. Now before the purists jump on me and say that stall is a function of AOA and not speed, I would think a light plane with less MOI up front would fly through the corners as opposed to sink.

--- End quote ---

Dick,

Your thoughts echo those of Bob Hunt. His Genesis Extreme had very small flaps and was designed for the mass weight at (or just in front of) the CG. I agree and my latest had much smaller flaps, too.

It is painful to admit you wasted many months of effort, but my Alouette-E suffers most from a short tail moment. I shortened the nose, but I should have learned from my original IC Alouette and made a longer tail. The IC powered version has a much longer tail moment than the norm and flies like it's on rails.

C'est la vie. I'll either build a new one this winter - or do the Al Rabe thing and cut off the whole tail and build a new one.  Either way, it's a lot of work. :P :P

Ron

frank carlisle:
I haven't sat down to draw a new plane for electric yet, but I have some definite ideas about what it's going to look like.
I'm thinking a tubular airfoiled fuselage with the nose being just large enough to enclose my AXI motor, then flaring out to make room for the battery pack, then tapering away to the tail.
The fuse will be bulkheads and stringer construction. Thin wing, low aspect ratio, no flaps, small stab and elevators, fuse mounted gear. Monokote.
I couldn't tell you it will be competitve or even that it will fly well but I do think it's time to dtart from somewhere else.

Dick Fowler:
Sounds interesting. I'm curious as to why you would want a low aspect ratio wing.

frank carlisle:
Well, Dick........................I've been looking at reducing drag and I think less span might do it. AND......I pretty much plan on modeling from now on so if this doesn't work it won't be the last. I'm figuring getting squares  from chord rather than span might work. I don't have any scientific way to predetermin this. So I'll build it. Unless of course you or someone else can come up with a better idea. Which I'd follow in a heartbeat if it had a chance of working.

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