why does my trainer climb so much?  
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All Forums >> RC Airplanes >> Beginners >> why does my trainer climb so much?
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why does my trainer climb so much? - 6/14/2003 11:49:52 AM   
faisalk


 

Posts: 313
Joined: 4/14/2003
From: karachi, PAKISTAN
Status: offline 		I have a 40 size trainer and a 46 size engine installed. Its usually very windy where i fly. At full throttle the plane climbs steeply and at even half throttle it climbs. I trimmed the elevator to down and i can literally see the elevator down from the neutral position but still the plane climbs. At 1/4 throttle it is level. Any idea if this is unusual or usual with trainers?
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why does my trainer climb so much? - 6/14/2003 12:06:49 PM   
MAJSteve


 

Posts: 322
Joined: 1/26/2002
From: Baghdad, USA
Status: offline 		If the engine is mounted with no up thrust, then the wing incidence is too positive. Put a 1/8 inch shim under the back of the wing at the fuselage and try it again. Put as much as necessary to get it to fly the way you want, then glue them in place.

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why does my trainer climb so much? - 6/14/2003 2:41:22 PM   
Banksy



Posts: 37
Joined: 5/23/2003
From: London(ish)Kent, UNITED KINGDOM
Status: offline 		I had this problem and when I tried a bigger prop, It helped.

Lost some top speed, but the plane doesn't try to go straight up on WOT any more, and there is still plenty of power available, The engine idles better and runs more smoothly as well, and slowing down for landings is easier.

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why does my trainer climb so much? - 6/14/2003 6:05:50 PM   
Tattoo



Posts: 2124
Joined: 2/10/2002
From: Wichita, KS,
Status: offline 		If your plane is built and balanced correctly, your aileron neutral position is too low. It's that simple.

Read this:
http://www.rcuniverse.com/forum/tm.asp?m=723406+neutral+position]

< Message edited by Tattoo-RCU -- Jun 14 2003 1:40PM >

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why does my trainer climb so much? - 6/14/2003 7:31:32 PM   
causeitflies



Posts: 357
Joined: 1/1/2003
From: Steubenville, OH, USA
Status: offline 		This is a design feature that has carried over from old trainers. Back when engines were low on power and instructors were few, the designers figured that if the plane was climbing slightly the guy trying to teach himself had a better chance of not crashing right away

Newer 40 sized engines perform like the old 60 sizes used to. But trainers are meant to be flown slow so with the excess power they climb. Almost all trainers I have seen needed one of the fixes above(all will work) even flying at slow to moderate speeds.

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why does my trainer climb so much? - 6/14/2003 7:42:07 PM   
greenboot



Posts: 1173
Joined: 1/16/2002
From: St Louis, MO, USA
Status: offline 		Your 46 has LOTS more power than the trainer really needs. 1/4 throttle is about all it really needs to fly level.

Flying with part throttle is good practice. Many Funfly and 3D planes are so overpowered they will come apart if flown level with full power.

Tom

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Re: why does my trainer climb so much? - 6/14/2003 9:01:57 PM   
Hossfly



Posts: 3925
Joined: 12/3/2001
From: New Caney, TX, USA
Status: offline 		[QUOTE]Originally posted by faisalk
I have a 40 size trainer and a 46 size engine installed. Its usually very windy where i fly. At full throttle the plane climbs steeply and at even half throttle it climbs. I trimmed the elevator to down and i can literally see the elevator down from the neutral position but still the plane climbs. At 1/4 throttle it is level. Any idea if this is unusual or usual with trainers? [/QUOTE]

If you have a flat bottom wing trainer, and the stab is mounted along the fuse centerline, then you already have positive wing incidence. The wing chord line starts at the center of the wing's leading edge, not the bottom of the wing. Aerodynamically the stab is already set with *up* elevator when flat, and will load the wing to a positive angle-of-attack (AOA) which produces lift.

Your problem requires engine down-thrust. Many trainers have some, many don't.
Reset your engine to 5 to 8 degrees DOWN from the fuse. (stab.)centerline.
You said the plane does not climb at 1/4 throttle. With the downthrust, additional power will pull the plane down and you will trim the elevator for level. When you retard the throttle, the "pull down" goes away but the trim setting should allow a fairly smooth transition to the low power glide. Experiment a bit.

Some old timers that I fly require up to 12-15* down thrust depending on Glide CG arrangements that I set up. Pattern ships use CG to arrange near same.

Flat bottom wings fly their aerodynamics, sym. fly theirs and all others in-between. For example, washing out the wing tips will reduce the Down-thrust required. The PILOT controls a plane, airplane-drivers wonder what's wrong.

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why does my trainer climb so much? - 6/14/2003 9:25:53 PM   
Jim C.



Posts: 730
Joined: 1/4/2003
From: armagh, PA, USA
Status: offline 		[QUOTE]require up to 12-15*[/QUOTE] like what type??? holy cow that seems like a lot......

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Mulligan Hill RC Club

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Like one of these? - 6/14/2003 9:36:31 PM   
causeitflies



Posts: 357
Joined: 1/1/2003
From: Steubenville, OH, USA
Status: offline 		Lanzo

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why does my trainer climb so much? - 6/15/2003 12:17:34 AM   
Eugoogoly


 

Posts: 179
Joined: 5/1/2003
From: In front of the computer, UNITED KINGDOM
Status: offline 		do you have a computer radio? If so you could put a mix in for the elevator to go down when the throttle is increased.

(in reply to faisalk)
       Post #: 10

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