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reinforcing ABC wings

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Old 11-19-2003, 12:39 PM
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shams42
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Default reinforcing ABC wings

So I've gathered from reading the many aerobird threads on this board that the large foam wing has the tendancy to fold during high-G manuevers like loops. I actually did a couple of loops on my third flight, but I was nervous the whole time that the wing would fold and my 'bird would lawn dart into the ground.

I'd like to hear people's thoughts on how to reinforce the Aerobird wing to prevent this from happening.

I've come up with a method that I will try during my next flight. I took a metal rod off of a heavy-duty clothes hanger -- the kind with clips. The rod is about 1/8" in diameter and about 15.5" long. I aligned the center of the rod with the center of the wing and taped it down. After I took these pictures, I started to worry about the tips of the rod digging into the foam when the wing tries to flex. I took an old CD case and broke it into fragments that I slipped beneath each end of the rod to prevent this from happening. Before flight, I will tape over the entire top surface of the wing with packing tape to smooth it out.

My concerns are:

a) Weight. I can't estimate how much the rod weighs but it did add a substantial amount of weight to the wing.

b) Balance. I tried to put the rod directly in the center of the wing (from side to side and from front to rear.) I don't know where the exact balance point of the plane is, so I'm a little concerned that I might have distrurbed it. I am sure that I have raised the CG of the airplane, which I expect will make the plane a little less stable.

c) Airflow disturbance. Even with the packing tape in place, the top of the airfoil now has a different shape. I do not know how this will affect the flight characteristics of the wing. If I had the proper tools, it would be ideal to cut a shallow groove in the wing surface so that the rod is not in the airstream.

I've attached a pic. I'd love to hear your thoughts and other ideas for reinforcing these wings.

Matt
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Old 11-19-2003, 03:23 PM
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Matt Kirsch
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Default RE: reinforcing ABC wings

I think you might want to rethink your reinforcement. It's overkill, like taking out a house fly with a hand grenade.

First, the TOP of the wing is what creates lift, and it depends on a fairly smooth surface. Taping a 1/8" rod to the top of such a small wing will drastically reduce lift.

Second, you've added a LOT of weight, behind the CG of the plane. This will make the plane harder to fly.

The tape by itself will be plenty of reinforcement. The best place to put the tape is on the bottom of the wing.
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Old 11-20-2003, 01:21 AM
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Default RE: reinforcing ABC wings

The wing on my Aerobird has a couple of dings in the front of one side (both from footy poles) and two cutouts from the prop (one on each side, one major (about on inch ) and one very minor. Both of them are taped over and the major one has as many foam fragments as I could find stuck back in. Does this increase my chance of a fold? Which moves are still safe to do?

(Also if you are interested please see my post aerobird troubles. I need some help.)
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