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#1) 
PostPosted: 27 Aug 2011 00:31 
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Joined: 18 Aug 2011 02:02
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What Would make an airplane roll to the left, turning completely upside down directly at the point of takeoff?


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#2) 
PostPosted: 27 Aug 2011 05:07 
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Joined: 23 Feb 2010 12:14
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Location: Brisbane QLD, Australia
Well, that depends on the plane and the circumstances. The most likely candidates are either being out of trim (in the roll axis), not enough airspeed before taking off or both! :(

If the roll trim is out then the plane can start rolling after take-off until you have a chance to trim it out. Usually it is a slow to medium roll but if the trim issue is bad enough it can be severe.

Not enough airspeed before lifting off is another likely cause as this can result in:
a) Not enough control authority in the ailerons to counter motor torque (front mounted/tractor motors most often roll planes leftwards from the torque they impart on the airframe)
b) Wing stall. One wing can stall before the other resulting in a roll due to aerodynamic assymetry. Or the wings can stall at full throttle and the full throttle motor torque simply then twist the airframe over.

A couple of my warbirds exhibit these traits. My Parkzone Mustang has a noticeable torque roll on hand launch to the left that needs a firm hand and for throttle to be backed off to about 80%. I watched one of our group launch his own for the first time at full throttle and it corkscrewed on him, caught him by surprise and augered in.

My larger Spitfire also displays all sorts of shenanigans on take-off from its wheels, and the motor is so powerful and tailfin ineffectual at slow speed the thing will often try to roll severely on me and jink left if I lift it off early (forced to do often from less than optimum "runways"). The darn thing has twice done a complete 180 turn on me on take-off and almost crashed.

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Ben


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#3) 
PostPosted: 27 Aug 2011 11:11 
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Location: Salisbury, England
Which plane is it?

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Pete


My site is rc-airplane-world.com, a beginners' guide to radio control flying.


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#4) 
PostPosted: 09 Sep 2011 22:25 
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Joined: 09 Jun 2011 20:31
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have you checked if motor is mounted properly? i was about a week+3 crashes fustrated until i found out that i have accidentaly mounted motor with left angle.... :)


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#5) 
PostPosted: 13 Sep 2011 03:10 
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Joined: 18 Aug 2011 02:02
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Thanks guys. The plane is a simple cessna type trainer. Electric, top wing. Three blades on the propeller. I tried to hand launch it, and it immediately rolled over and went down. :mrgreen: :?:


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#6) 
PostPosted: 17 Sep 2011 20:48 
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Joined: 09 Jun 2011 20:31
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emm...hand launched with or without throttle? if without than problem is your control surfaces is not aligned properly... if with throttle... well im having the same problems with my current toy somethimes but thats due to my dumb fingers mount the motor with angle... :(


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#7) 
PostPosted: 08 Nov 2011 22:00 
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Joined: 08 Nov 2011 05:00
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Don't forget that taking off with a crosswind can also cause the roll. If the wind gets under the windward wing it can cause you problems so give it a bit of aileron to compensate.


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#8) 
PostPosted: 10 Nov 2011 23:34 
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BLMitchell
It certainly sounds like something is wrong with your plane and possibly how you are trying to fly it.
Does it have ailerons (4ch) or just elevator and rudder (3ch)?
Could you post a picture(s) of it?

I don't know how experienced you are with RC planes but if possible I would get someone who is to check it over.

You could expect a properly set up high wing trainer type to make a pretty good job of flying without any input from you so something is not right.


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#9) 
PostPosted: 11 Nov 2011 01:52 
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Joined: 03 Aug 2011 11:47
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Location: west mids uk
can u get a picture up with it switched on so we can see how your surfaces r set

also might be a daft question but ailerons arnt reversed r they and u didn't inadvertently increase imput making it worse

and lastley when u hand launched did u throw it without motor running then put full throttle on , was wondering if u did then maybe it was all the torque coming in at once that made it roll

be carefull your not imputing rudder too when u grab stick to throttle up when u launch if your mode 2, aileron if your mode 1, think it aileron on same stick mode 1 anyway not sure as i fly mode 2


sean


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