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Jul 05, 2018, 10:24 AM
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Questions from a novice - Reichard Elipsoid


Greetings all,

I have been learning the sport of soaring with a Reichard Elipsoid. I've noticed two situations for which I would like some advice.

#1 - If I dive a little too aggressively the wings will flutter and I panic. Anything I should do other than keep the speed really low with this glider and just enjoy the slow thermal hunting?

#2 - For the last three flights I have had the glider return to me with each wing about 3/16" to 1/4" separated from the fuselage. I'm using a high tension spring through the fuselage to connect the wing roots. I've shortened the spring after each flight to the point where it takes a good effort to stretch it to connect the roots. The wing separation still occurs.

I think the answer to #1 is to fly like I'm on a sunday drive.

Not sure what to do about #2. Can I use polyethylene tape over the wing-to-fuse joints? Any other suggestions?

Many thanks!
- evan
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Jul 05, 2018, 11:18 AM
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Flutter is tough, and if your airplane displays flutter, the only thing to do is avoid it as you have, by slowing down. Sorry. I hope your next airplane is a more capable design.

For the wings, by all means tape them. Even if the tape stretches, it should still cover the gaps and that always helps reduce drag. I do not recall exactly how the Ellipsoid wings go together, but if there is a wing rod, you can rub it with beeswax. Get a life-time supply by picking up a cake at most natural food markets. The beeswax lubricated the rod/tube combo as the wing slides on, then sticks until you pull the wing off.

Good luck.

Yours, Greg
Jul 05, 2018, 11:32 AM
Still circling in sink...
I'm not familiar with the Ellipsoid other than what's on the web, but it looks as if it has ailerons but no flaps or spoilers. Without flaps or spoilers it could pick up speed quickly in a dive to the point that flutter might become an issue. A couple of thoughts:
1. Add a spoileron function, so that you can raise both ailerons a lot (45 degrees or so) to act as airbrakes. That will help some.
2. Check that there's no slop in your aileron linkages. if there is, rework them to eliminate it. Slop in linkages contributes dramatically to flutter.

As for the wing separation , yes, use tape. Most people use electrical tape and it works fine. A roll of kapton tape is even better but electrical is convenient and cheap.

Also note that flutter can cause the wings to work their way out on the joiner, and wings that are less rigidly attached to the fuselage will flutter sooner. If you address both problems at the same time, you might see some synergy in how effective they are together.
Jul 05, 2018, 12:01 PM
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craigrrr's Avatar
Concerning your aggressive diving, if you are diving in order to loose altitude (maybe because you lack spoilers) consider flat spinning your plane; give it a full up elevator and a full right rudder. At first do this at a moderate altitude (not too low, but not near spec, so you can observe the results and stop it if desired).

Flutter should be absolutely avoided.

Craig
Jul 06, 2018, 01:00 PM
Registered User
Many moons ago I also had a glider that "got nervous at higher paces" and sunday driving was key to keep it happy
Cheers
Jul 06, 2018, 06:51 PM
Registered User
Ok, for the flutter, the first thing to check is if there is any slop. The more rigid you make the linkage, and the tighter you make the hinges, the less vulnerable to flutter your model will be. If you end up re-hinging the ailerons, weigh them and see just how heavy they are. Lighter is better, as long as they're at least moderately stiff in torsion. While you're at it, check for slop in the other control linkages as well.

You might also try twisting the wings, to see if they're stiff in torsion. If it's an open bay structure, you could try adding another layer of covering for the inner 1/3 of the wing. See if you can find out what it came with, and use the same stuff. You can probably apply it most easily with the "Windex trick", which I'm sure a search of RC Groups will uncover. However, I haven't used it all that much, and not on an application quite like this, so I can't promise anything.

Hypothetically, a little bit of weight in the leading edge, out near the tips might help. But this is tricky, especially if you use much weight.

Does the wing rod fit snugly? Slop might be a problem here as well.

Flutter can destroy a wing very quickly, so be careful.

I'm wondering if #2 is because of #1. It seems like an unusual problem. Tape, of course, is a good idea. I use a good grade of electrical tape. You may want to put some robust kind of tape down permanently so that when you peel off the electrical tape, it doesn't take the covering with it. People have also done things with magnets, or you might try, in addition to the spring, tying the two hooks or screw eyes or whatever they are together with strong twine.
Jul 08, 2018, 04:28 PM
F3Foamie Pilot
I use the spin technique to get gliders down that can't handle a terminal dive.

Inverted is my favorite with my TG-3.


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