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06-21-2013, 06:57 PM | #1 (permalink) |
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Join Date: Oct 2012
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E-Flite zero pitches up with full throttle
Hi, I have a Zero that turns its nose up a little when I go full throttle and I have to put a little down elevator to keep the nose level. The CG appears to be spot on so I don't know what's going on. Any help appreciated.
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06-21-2013, 07:10 PM | #2 (permalink) |
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Join Date: Feb 2009
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It is likely CG related. Fly at 2/3 throttle and trim for level flight. Roll inverted and see which way it pulls. If it pulls hard to the canopy then your CG is too far forward. Move your battery back a little at a time till you can roll inverted and only have a slight pull to the canopy. This should sort out your pull to canopy with throttle.
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Ivan |
06-21-2013, 07:34 PM | #3 (permalink) |
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Join Date: Jan 2006
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It probably has an undercambered or semi-symmetrical airfoil, if so, if CG corrections do not help (it is probably a downthrust issue), try adding a very little bit of down throttle to down elevator mix in the radio.
A friend of mine had one of the EFlite Micro DeHavilland Mosquitos (neat little airplane) which wanted to nose up with full throttle. Adding the mix in the radio corrected it-the aircraft stayed level at any throttle setting with the mix. I did the same with my Banana Hobby P-38 (which has an almost flat bottomed airfoil) to correct unwanted climb with throttle.
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06-22-2013, 11:12 AM | #4 (permalink) | |
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Thread Starter
Join Date: Oct 2012
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E-Flite zero pitches up with full throttle
Quote:
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06-22-2013, 11:39 AM | #5 (permalink) |
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Join Date: Jan 2006
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Cool!
Make the mix very, very small and sneak up on the test flying, so that you don't go to full throttle and have the ship nose down. It usually just takes a couple of degrees of down at full throttle.
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06-25-2013, 09:18 AM | #6 (permalink) |
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Join Date: May 2013
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This is typical of many planes. Just get on the trim or elevator when hauling arse.
Bubba |
06-28-2013, 04:35 AM | #7 (permalink) | |
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Join Date: Oct 2010
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Quote:
Lift on an airplane is directly related to airspeed which is partly related to throttle. From level flight More throttle -> increasing speed -> more lift/nose pitches up. The plane climbs but that climb requires energy so the speed will remain fairly constant as the plane climbs. Less throttle -> decreasing speed -> less lift/nose drops. The plane sinks and trades off altitude for more airspeed. Result is a descent at about the same airspeed as before. To remain at straight and level flight, you'll need to trim the plane out for any change of throttle setting. As far as I can understand, anyway : )
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07-03-2013, 09:35 AM | #8 (permalink) |
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Location: Massachusetts
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Also understand that if the plane has a flat bottom or cambered airfoil the inverted flying CG test will NOT work. No matter where the CG is you will need a lot of down elevator to hold it.
An alternate CG test that might work better is the dive test... From trimmed level flight, initiate a shallow dive (say around 30deg) and let go of the sticks. A properly trimmed plane will gently level out on its own. If it pulls back to level very fast its nose heavy. If the dive steepens, its tail heavy. (this may seem counter-intuitive) Some down thrust will help but dont obsess over this - its not an aerobatic ship and no matter what you do you wont be able to get it flying completely neutral.
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07-04-2013, 07:21 AM | #9 (permalink) |
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don't forget what the primary controls actually control.
throttle controls height, airspeed over wing generates more lift as mentioned above. elevator controls speed via angle of attack. the best example is a jet landing, they set the throttle and leave it alone controlling the speed of the approach via the elevator. do the dive tests mentioned above, but a properly trimmed plane will usually climb when the throttle is firewalled.
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07-05-2013, 01:41 PM | #10 (permalink) |
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Join Date: Jan 2006
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Again, it is very easy to use the mixes.
These are functions in most of our modern, computerized radios that most of us simply ignore. Same for using mixes on flap equipped airplanes, works very well. You can cure the issue in under 10 minutes doing this (elevator trim will automatically adjust in relation to throttle setting, eliminating the tendency to climb when throttle is increased and dive when throttle is decreased).
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07-05-2013, 02:30 PM | #11 (permalink) |
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Join Date: Oct 2012
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E-Flite zero pitches up with full throttle
Thanks for the replies everyone. I added just a hint of elevator mixed at full throttle....and tested and it still pitched up ever so slightly...nowhere near as bad as before. Then I trimmed it at full throttle and it still flies pretty level off the throttle so I'm calling a success (as far as flying skills are concerned!!)
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07-05-2013, 02:52 PM | #12 (permalink) |
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Join Date: Jan 2006
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"Thanks for the replies everyone. I added just a hint of elevator mixed at full throttle....and tested and it still pitched up ever so slightly."
Outstanding! If you want to, you can add a bit more mix, until the tendency goes away completely. Just do it a bit at at time. It took about three adjustments on the Mosquito and the P-38, to get it where the tendency to climb or dive based on throttle setting was completely erased.
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