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Plane wants a whole lot of nose weight

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Old 07-27-2016, 01:11 AM
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3357
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Default Plane wants a whole lot of nose weight

i picked up an old Spectrum Alpha trainer with the 63" wing span from a friend of mine
He flew it one time after he bought it about 10 years ago and then it got stepped on in his garage and has laid wounded every since. it was crunched pretty good from where the back dowel for the rubber bands is back to the tail feathers. I thought I could probably fix it so i brought it home . It took me a few days to do but it is fixed and arf.
When I went to balance the model I figured it would be tail heavy but I had no idea it would want 1.34 pounds of nose weight to balance. My god, I didnt put any steel I beam or any thing like that in when I repaired it. I ran a 3/16" balsa skin on one side from where the back dowel is to the back. And then there is epoxy and a a few small pieces of balsa here and there in the rear inside the fuselage but only where it was necessary
Didnt even use all of the small bottles of epoxy. I kept in mind when I was repairing it that that far back on the fuselage weight matters so I used only what i had to.. Before I tried to balance it I even moved the battery pack as far forward as possible.. My god 1.34 pounds??? Will that plane even fly if I put that much nose weight on it ??? Never have used any where near that much weight. What do you guys think? Did I wast my time on a doomed plane??? Or do you think it might fly?? I really dont know.

Thanks Dave
P.S. The plane has an evolution .45 motor

Last edited by 3357; 07-27-2016 at 01:15 AM.
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Old 07-31-2016, 10:04 PM
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chuckk2
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Move the wing back until the balance looks good, then remount the wing.
I had to do this with an ALFA 25 trainer
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Old 08-09-2016, 06:45 PM
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really? that would work?. Never thought of that.
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Old 04-12-2018, 06:50 AM
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r ward
 
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I had to do that with a coro trainer ( plans from SPAD to the Bone) that I built, too.
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Old 04-12-2018, 07:35 AM
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Yeah, the center of lift won't change on that wing.. so if you can extend the wing saddle back and keep the incidence the same it transfers some weight to the front of the cg, and subtracts it from the back ! its a great trick. It could change the handling of the plane some as you are shortening the tail moment..
That is basically why so many Scale type planes have stretched noses.. especially WW1 planes. Thats the easiest way to get the plane to balance out without hanging an anvil up there You are in essence moving the wing back.. by extending the nose.
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Old 11-19-2018, 05:45 PM
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extending the nose is a lot better than adding a bunch of weigh. I try to build to balance as much as I can. after you build enough planes, you get an idea of how it's going to balance by hanging the motor on the nose as construction proceeds. sometimes I get lucky and only need a few ounces, sometimes I have to get inventive figuring how to get the engine mount forward enough to balance out. best thing to do is to build the tail of the plane (from trailing edge of main wing back) as light as possible but still strong enough for the forces involved. if the plane turns out a little nose heavy, it's easy to cure, but if it's the least bit tail heavy the remedy can only result in less performance, or a busted plane.
you know the saying......
one thing about rebuilding a lane after a crash. think in terms of large areas, replace all those little pieces that might fit together real good with a whole piece of the same shape, or even a whole side or top or bottom of the fuselage. all the glue to stick all those pieces back together can add up and turn a plane into a tail heavy slug. having to rebuild a fuselage is good opportunity to redesign the tail construction of a plane that was maybe a little tail heavy, but flew "OK" with a lump of lead in the nose. try to eliminate the need for that lead, or at least reconstruct the plane to reduce the weight needed by moving the engine ahead and making the tail lighter as you rebuild. a little creative thinking about structure and the sizes of the pieces you are using, can solve a lot of problems.
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