SMALL - espritmodel.com SMALL - Telemetry SMALL - Radio
Reply
Thread Tools
Old Apr 30, 2011, 07:37 PM
Registered User
Joined Nov 2010
7 Posts
Discussion
When to Trim/when not to trim?

newbe question, once plane is trimmed do you need to retrim every time you fly? Should you trim while on ground? Once trimed, do I go back and adjust servos, horns and get tx back to netural point?

Thanks
Jamcon is offline Find More Posts by Jamcon
Reply With Quote
Sign up now
to remove ads between posts
Old Apr 30, 2011, 08:40 PM
Shelter Kitty "Orange Death"
bartricky's Avatar
United States, FL, Monroe
Joined Jan 2008
3,165 Posts
Quote:
Originally Posted by Jamcon View Post
newbe question, once plane is trimmed do you need to retrim every time you fly? Should you trim while on ground? Once trimed, do I go back and adjust servos, horns and get tx back to netural point?

Thanks
Pick a very calm day and trim for (as close as you can get to) hands off straight and level flight. Trims should remain good unless something changes with the plane.
If you hand launch sometimes a little up elevator trim is necessary for launch.
bartricky is offline Find More Posts by bartricky
Reply With Quote
Old Apr 30, 2011, 08:49 PM
Frequent Flyer
whitecrest's Avatar
Orleans, MA
Joined Feb 2007
2,089 Posts
Quote:
Originally Posted by Jamcon View Post
newbe question, once plane is trimmed do you need to retrim every time you fly? Should you trim while on ground? Once trimed, do I go back and adjust servos, horns and get tx back to netural point?

Thanks
Welcome to the forum!

Once you have the plane trimmed to your satisfaction, note the degree of adjustment required for future reference. If you needed a great deal of trim, I would recenter the servo arms to provide enough room for future adjustments.

I always check the trim before each flight now because temperature and humidity can make significant differences in the trim adjustment which will noticeably affect flight performance. The fuselage and/or the pushrods will change length with these atmospheric variations.

You will probably notice that very small trim adjustments can significantly impact flight characteristics.
whitecrest is offline Find More Posts by whitecrest
Reply With Quote
Old May 01, 2011, 12:05 AM
WARNING: May contain spam
Xpress..'s Avatar
United States, CA, Alpine
Joined Oct 2007
20,936 Posts
Eh, sometimes you will need to add a couple of clicks of trim, but you should notice the need to do this very quickly. Sometimes, an airframe will fly straight as an arrow for its entire lifetime.
Xpress.. is offline Find More Posts by Xpress..
Reply With Quote
Old May 01, 2011, 12:25 AM
Registered User
Livermore, CA
Joined Sep 2004
8,582 Posts
I usually trim my planes for level control surfaces. I test fly it and make a pass at medium cruze speed, and trim it for hands off level flight. Then I bring it in and see if the elevator is in the netural/level position. If not, I move the battery forward or back till it is. Then I make sure the battery always sets in the same spot and before I launch I check to see that the control surfaces are all level.
Like already said, some times a couple clicks of UP trim helps on a hand launch.
Butch777 is offline Find More Posts by Butch777
Reply With Quote
Old May 01, 2011, 07:49 AM
An itch?. Scratch build.
eflightray's Avatar
South Wales U.K.
Joined Mar 2003
13,406 Posts
Quote:
Originally Posted by Jamcon View Post
newbe question, once plane is trimmed do you need to retrim every time you fly? Should you trim while on ground? Once trimed, do I go back and adjust servos, horns and get tx back to netural point?

Thanks
No and yes.

No, you shouldn't need to retrim each time you go flying, unless the plane requires it for each speed range change.

Yes, it is a good idea to adjust the control surfaces so that the Tx trims can be set back to neutral if possible.

Now I prefer to trim for a slightly nose down glide, (no motor on), then if the motor does stop the speed should still be enough to give good control and it keeps it away from a stall.

I would trim for powered flight by adjusting down thrust if required to give a level flight at a fast-ish cruise. For full throttle, I would trim to suit what I required and the conditions.

Remember, the throttle is usually for climbing and descending, (it's not an on-off switch but a progressive control like the others). The elevator trim is to trim the plane for level flight at fairly fixed speeds once you select a height/speed. Full elevator control is for aerobatics, having fun, and those aarrrgg! situations to get you out of, (and sometimes into), trouble.

Most, (all ?), trainer planes, and many general models that don't have a fully symmetrical wing section, will climb with increased throttle. So if you want to fly faster from say just cruising along, but not keep climbing, you need to re-trim the elevator to compensate all that extra lift that come from increased speed.
eflightray is offline Find More Posts by eflightray
Reply With Quote
Old May 01, 2011, 08:55 AM
Registered User
United States, MI, Monroe
Joined Jun 2009
2,043 Posts
Once trimmed, I adjust arms and clevis, I try to get the radio trims centered. Just funny about it. Very rarely after that do I need any adjustments. When running two different weight batteries though I use battery placement to keep COG. A click or two is the most I usually have to adjust on elevator when switching between pacs.
Tony K is offline Find More Posts by Tony K
Reply With Quote
Old May 01, 2011, 01:51 PM
fmw
Registered User
fmw's Avatar
Joined Jul 2009
1,955 Posts
The real answer relates to your transmitter. If you have a digital, programmable transmitter then the trim settings are saved in the model memory. If you have a manual transmitter, you need to change trim every time you change airplanes and any time you move the trim sliders.
fmw is offline Find More Posts by fmw
Reply With Quote
Old May 01, 2011, 06:36 PM
Registered User
Wallingford, Ct
Joined Sep 2001
1,913 Posts
If you constantly keep turning,climbing,diving, etc, you don't have to trim. Nobody can tell the difference including you.
Al M is offline Find More Posts by Al M
Reply With Quote
Old May 01, 2011, 07:30 PM
Registered User
V2rider's Avatar
USA, MD, Hagerstown
Joined Jun 2009
3,349 Posts
Quote:
Originally Posted by Xpress.. View Post
Eh, sometimes you will need to add a couple of clicks of trim, but you should notice the need to do this very quickly. Sometimes, an airframe will fly straight as an arrow for its entire lifetime.
And then there are planes that will need to be trimmed every time you take them out. My PZ 109 is one of these. The vert/hor stabilizers are a different shape every time I take it out. Flys good after a few clicks here and there, but never seems to be the same from one flight to the next.
V2rider is offline Find More Posts by V2rider
Reply With Quote
Old May 02, 2011, 05:18 PM
Registered User
United States, NJ, Frenchtown
Joined Mar 2003
9,127 Posts
THose super thin surfaces that bend a lot are VERY bad after being creased.
cyclops2 is offline Find More Posts by cyclops2
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Discussion Flaperon trim not working on Jr XP9303 gmony Radios 2 May 01, 2011 03:39 PM
Discussion Registering to fly and camp at SEFF....when you did not pre register Jeff Meyers SEFF 2011 3 Apr 04, 2011 12:21 PM
Discussion Elevator Trim Change when Gear go up or down zoomer02 Hitec/Multiplex USA 3 Mar 31, 2011 02:18 PM
Help! Not enough control in Trim dial to stop spin yeswedeliver 3D Electric Heli Flying 1 Mar 28, 2011 05:25 PM
Discussion Not shipping when claimed? Rich in ILM HobbyPartz.com 13 Mar 14, 2011 04:06 PM