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Hubris, and a series of unfortunate events.

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Hubris, and a series of unfortunate events.

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Old 01-02-2018, 09:29 AM
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Broken
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Default Hubris, and a series of unfortunate events.

I've got nerves of steel and have flown everything under the sun big to small, fast to slow, fixed to rotating. So when Christmas break was upon us I thought it would be fun to build a glider with my boys that I had been storing away. What a fun way to ramp up into the holidays and show my boys some good ole fashion build to flying. And teach them how to fly etc.. etc.. So out came the Carl Goldberg Electra. And we and (I) assembled it in a few days. Did some covering added the electronics. And away we went. I live next to a park so we went out to do range check and "first flight" it. Did I mention hubris, and my amazing abilities yet? So- "First Flight" After some initial CG, power, hand to ground glides, I threw it out for a powered climb. I have lots of power and small weight due to the small lipo batteries. (my other hobby).

The Flight! The Electra climbed well but I immediately noticed that it needed a lot of rudder to go straight. At this point I went for altitude to get a few mistakes high as I leveled it out my increasing need for rudder was outpaced by the hard left it was entering and I ran out of rudder. Speed aggravated the turn and the downward spiral added speed. All that was left was to cut the power. I flew it into the ground attempting recovery until the last moment. I got lucky here. The plane filtered through a tree with minimal fuselage damage, but the wings....... Upon reconstruction I noticed a warp to one of the wing tips. I did not see it before. (I did not look either). The warp is consistent with the observed flight of the model so.....

The rebuild! I decided to not use the original wing but i needed a wing ASAP because i want this model to fly dammit. So i designed a wing in CAD and I am 3D printing the parts (see pics) The ribs are done after a day of printing and assembly can begin. This is a simple replacement so the Wing Ribs are 3mm thick and hollow lattice in the root and 1.5mm with hollow lattice at the ends. Simple lightweight and strong. I am adding ailerons with a simple dihedral wing. The original was polyhedral without ailerons.
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Old 01-03-2018, 12:02 PM
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Sorry for the troubles. If the wing in your first pic is what you flew with, the warp didn't help but the real culprit is the shallow polyhedral angle at the tips. You definitely need more than that. I'm 100% certain it's not built to the plan spec. Fix that and you will have nice control. Rereading your post is sounds as if the pics are actually of the replacement wing. Same issue though, need more poly.
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Old 01-11-2018, 05:12 AM
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Upon reconstruction I noticed a warp to one of the wing tips. I did not see it before. (I did not look either). The warp is consistent with the observed flight of the model so.....
Ailerons are great, but wing warping can be caused by the iron on covering on a wing designed with no sheeting, You can build the straightest wing in the world on the bench but proper fine tuning of the washout and straightening is done post covering with a heat gun and twisting.

good luck with the new wing

Last edited by scale only 4 me; 01-11-2018 at 05:15 AM.
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