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  #41  
Old 04-22-2019, 08:31 AM
aeppel_cpm aeppel_cpm is offline
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Okay glider fliers, I would like opinions:

It took 7g of wingtip clay to trim the left roll out of my glider. Would I be better off with the lump of clay on the wingtip, or making an aileron?

My thought is that they would behave nominally the same during glide, but may behave quite differently during boost.
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  #42  
Old 04-22-2019, 08:39 AM
jetlag jetlag is offline
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ALWAYS achieve the balance of the aircraft first.
Then can use a little aileron. You may find a little rudder is all that is needed.
If you use only aileron to correct roll, the effect magnifies as the craft increases airspeed. Increasing your dihedral is another way to make the aircraft seek level flight. If you need more lift, either slide the wing forward a little (if possible) or increase the wing leading edge angle of attack slightly. It's important to do only one adjustment at a time, so you can tell immediately whether the one adjustment you performed worked.
Balance first. Then test fly.

Allen
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  #43  
Old 04-23-2019, 07:09 AM
aeppel_cpm aeppel_cpm is offline
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Thanks for the guidance, jetlag.
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  #44  
Old 04-23-2019, 09:50 AM
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ghrocketman ghrocketman is offline
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+1 to what jetlag just said.
Balance first, aileron/rudder second.
That thing sure is requiring a LOT of weight though.
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  #45  
Old 04-23-2019, 10:12 AM
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Quote:
Originally Posted by ghrocketman
+1 to what jetlag just said.
Balance first, aileron/rudder second.
That thing sure is requiring a LOT of weight though.



Yeah, that was my first thought. 19g...........almost 3/4 oz. Yikes! Any suggestions as to how to correct the problems without adding so much weight? I'm particularly interested in this thread because I built a couple of gliders last year and have done test glides, but I still haven't gotten up the nerve to boost them.


Joe
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  #46  
Old 04-23-2019, 10:23 AM
aeppel_cpm aeppel_cpm is offline
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Recall, it started off at 200g.

Given that I'm upscaling a Tercel, I don't know that I could have done much to make the fore-aft balance better. I don't think the tail is -that- overbuilt, or that the RC horns are adding that much weight. I think it's part of the design and upscaling it just amplified the noseweight needed. That said, I noticed after testing that I had left a little up elevator trim in the servos from the last test. So it probably doesn't need -quite- 12g up front.

The 7g on the wingtip bothers me more. I sanded my own airfoils out of foamcore and then laminated 1/32" balsa over them. I suspect that I just ended up unsymmetrical in either the original sanding, or in the lamination (it was vacuum bagged) and that the angle of attack is different left vs right. And that's just poor construction skills on my part. To my defense, it -is- my first attempt at a glider this size, or using these techniques. I didn't want to spend the money on a kit, so I scratch built, and am suffering the consequences. Though I did enjoy most of the build itself.
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  #47  
Old 04-23-2019, 10:47 AM
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How about "lightening" the heavy wing tip ?
Punch holes in the solid material near the tip then cover with Monokote ?
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When in doubt, WHACK the GAS and NEVER touch the brake !!!
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, if you have to ask, you probably aren't
!
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  #48  
Old 04-23-2019, 10:55 AM
aeppel_cpm aeppel_cpm is offline
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From the hang tests, I don't think the other wingtip is actually heavy - I think I've got a differential lift problem. Which will vary with airspeed.

I don't know that I can take out 7g and leave much of the other wingtip remaining :-)
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  #49  
Old 04-23-2019, 01:30 PM
jetlag jetlag is offline
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You might be surprised.
7g is just 1/4 ounce. GH is right. You can lighten the heavy side, then use less weight on the light side. Your weight difference most probably is due to variation in the balsa density. 1/4 ounce could easily be due to this issue.
Correct one thing at a time. Get that right. Then see what else can be done.
Please let us know how it goes!
I'd be happy to trim it for you, but you'd have to send it to me.
Good Luck!
Allen
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