News:



  • March 28, 2024, 10:07:08 AM

Login with username, password and session length

Author Topic: basic trim question  (Read 1576 times)

Jim Roselle

  • Guest
  • Trade Count: (0)
basic trim question
« on: September 11, 2014, 08:18:27 PM »
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

Offline Paul Smith

  • 24 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 5793
Re: basic trim question
« Reply #1 on: September 11, 2014, 08:37:32 PM »
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.
Paul Smith

Online Brett Buck

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 13716
Re: basic trim question
« Reply #2 on: September 11, 2014, 08:55:59 PM »
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


Offline Howard Rush

  • 22 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 7805
Re: basic trim question
« Reply #3 on: September 11, 2014, 09:11:59 PM »
Are the wings rocking in roll (around the fuselage axis) or yaw (around the vertical axis)?
The Jive Combat Team
Making combat and stunt great again

Jim Roselle

  • Guest
  • Trade Count: (0)
Re: basic trim question
« Reply #4 on: September 11, 2014, 09:23:43 PM »
Are the wings rocking in roll (around the fuselage axis) or yaw (around the vertical axis)?
Roll.

Online Paul Walker

  • 23 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 1626
Re: basic trim question
« Reply #5 on: September 11, 2014, 10:50:28 PM »
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.

Offline Randy Cuberly

  • 21 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 3674
Re: basic trim question
« Reply #6 on: September 12, 2014, 01:10:30 AM »
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
Randy Cuberly
Tucson, AZ

Jim Roselle

  • Guest
  • Trade Count: (0)
Re: basic trim question
« Reply #7 on: September 12, 2014, 12:02:37 PM »
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

Offline Dan Bregar

  • 24 supporter
  • Trade Count: (0)
  • Captain
  • *
  • Posts: 690
  • Field Marshall
Re: basic trim question
« Reply #8 on: September 12, 2014, 12:40:32 PM »
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
AMA 33676

Online Brett Buck

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 13716
Re: basic trim question
« Reply #9 on: September 12, 2014, 01:38:11 PM »
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

Offline Tim Wescott

  • 2016 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 12804
Re: basic trim question
« Reply #10 on: September 12, 2014, 02:59:51 PM »
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.
AMA 64232

The problem with electric is that once you get the smoke generator and sound system installed, the plane is too heavy.

Offline Randy Powell

  • 21 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 10484
  • TreeTop Flyer
Re: basic trim question
« Reply #11 on: September 12, 2014, 03:13:02 PM »
>> I never trust anything that is not posted to an internet message board. <<

And Brett has learned sarcasm. Cool.
Member in good standing of P.I.S.T
(Politically Incorrect Stunt Team)
AMA 67711
 Randy Powell

Offline Randy Cuberly

  • 21 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 3674
Re: basic trim question
« Reply #12 on: September 12, 2014, 07:25:49 PM »
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
Randy Cuberly
Tucson, AZ

Offline Bob Reeves

  • 2016 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 3415
    • Somethin'Xtra Inc.
Re: basic trim question
« Reply #13 on: September 13, 2014, 02:16:28 AM »
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.


Advertise Here
Tags:
 


Advertise Here