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General control line discussion => Open Forum => Topic started by: Jim Roselle on September 11, 2014, 08:18:27 PM
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Hello all,
I am pretty new to the hobby, at least to the larger planes. last time I had my F-Twister out I realized I had gotten some bad advice on the CG initially. I removed the brass "Heavy Hub" prop nut I was advised to use and replaced it with the stock nut. Great results, I can actually do something close to a square loop now. The problem is that the wings now rock back and forth pretty good on the tight corners. I have adjustable leadouts installed.
Where to begin trimming?
thanks,
Jim
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It sounds like excess tip weight.
If you support the plane on the centerline, how much weight do you have to stack on the INboard tip to make it level.
This is the TRUE net tip weight.
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Hello all,
I am pretty new to the hobby, at least to the larger planes. last time I had my F-Twister out I realized I had gotten some bad advice on the CG initially. I removed the brass "Heavy Hub" prop nut I was advised to use and replaced it with the stock nut. Great results, I can actually do something close to a square loop now. The problem is that the wings now rock back and forth pretty good on the tight corners. I have adjustable leadouts installed.
Where to begin trimming?
Tip weight, probably. See which way it initially rolls on inside and outside corners. If it rolls away from you in both directions (right on insides and left on outsides), take out a bit at a time (maybe, 1/8 ounce) and try again. If it rolls toward you in both directions (to the left on insides and the right on outsides), add tip weight and try again. If it is different from inside to outside, there's some other issue.
Theres a lot of possibilities but fortunately lots of other threads where basic trim is discussed. Sealing hinge lines before you start is always a good idea, calculating the baseline leadout position is a good idea, and adjusting the rudder to neutral is usually a good idea.
Brett
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Are the wings rocking in roll (around the fuselage axis) or yaw (around the vertical axis)?
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Are the wings rocking in roll (around the fuselage axis) or yaw (around the vertical axis)?
Roll.
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I understand that there is a whole series of articles about trimming a stunt plane in "Stunt News".
Sounds like that would help you work your way through this.
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There's also a recent post on SS (the other forum) addressing this same problem on exactly the same type of airplane. It's listed a "rolling on a profile".
It might be worthwhile to look at that also.
Pauls suggestion about the Stunt News articles is a really goood one!
Randy Cuberly
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Thanks guys,
I ended up removing 1/4oz tip weight and it is much better. I will also try and track down those stunt news articles.
Jim
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I understand that there is a whole series of articles about trimming a stunt plane in "Stunt News".
Sounds like that would help you work your way through this.
And I think the gentleman who wrote these articles, may have even been a Nats Champ once or twice or 5 or 6 times. Who can keep track , I have to use a calculator !!! :) Yeah, these are good tips for us rookies to learn how to trim a stunter. I'm grateful to Mr. Walker & Mr. Hunt for publishing these pearls. :)
Dan
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I understand that there is a whole series of articles about trimming a stunt plane in "Stunt News".
Sounds like that would help you work your way through this.
I never trust anything that is not posted to an internet message board.
Brett
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I understand that there is a whole series of articles about trimming a stunt plane in "Stunt News".
Sounds like that would help you work your way through this.
I love those articles. The only fly in the ointment is that when I'm at the field and I pull my copy out of my flight box (that's how much I love those articles), I can't find the places where you say "if it does A, then change X". I need to go over it with a highlighter and cross-index all of the problems to the corresponding prescriptions.
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>> I never trust anything that is not posted to an internet message board. <<
And Brett has learned sarcasm. Cool.
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And I think the gentleman who wrote these articles, may have even been a Nats Champ once or twice or 5 or 6 times. Who can keep track , I have to use a calculator !!! :) Yeah, these are good tips for us rookies to learn how to trim a stunter. I'm grateful to Mr. Walker & Mr. Hunt for publishing these pearls. :)
Dan
Awwwww...Those guys are so good and talented they don't even need to trim an airplane...They could fly a wheelbarrow with wings and win!!! LL~ LL~ LL~ LL~ LL~ LL~ LL~
At least I've heard that said!
Randy Cuberly
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I'm no expert but this works for me.
Set the leadouts where LineIII says to, fly the airplane and do the OTS climb. From level flight make the tightest inside corner you and the airplane will turn, fly straight up then make the tightest outside corner you can back to level flight. If the outboard wing dips on the inside and rises on the outside remove tip weight until it turns flat. If it rises on the inside and dips on the outside add tip weight till it turns flat. This is assuming a straight airplane with no wing warps and the rudder has 0 or very little offset.