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Old Jul 30, 2003, 05:42 PM
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United States, VA, Warrenton
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Help with nose high E3D at low throttle

I pulled out my E3D the other day after a long time in storage. With only 1 10-cell pack and great difficulty getting it in and out of my Mazda Protege, and a small crash that busted my nose, I hadn't flown it in a long while. Well, I fixed it up with some new lite-ply and made a very simplistic removeable wing - rubber band trainer wing style. This isn't the point of my post, but I wanted to put a picture of it up. It has held up well so far.
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Old Jul 30, 2003, 05:46 PM
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But onto the question

Anyhow, my question is, my E3D seems to want to go to a nose high attitude at low throttle, and I'm trying to understand what would cause this. The CofG is about 4" from the leading edge of the wing. I have taken a couple of pictures to try and show the alignment of the wing, elevator and motor. In the pictures, the movable part of the elevator is slightly down, but the fixed part has been leveled with a bubble level. The bubble level also shows level when placed on the nose above the motor.

What kind of incidence would cause a plane to pitch up?

Here's the overall shot:
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Last edited by Ninjak2k; Jul 30, 2003 at 05:49 PM.
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Old Jul 30, 2003, 05:47 PM
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And here is a close up of the motor and wing.
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Old Jul 30, 2003, 06:00 PM
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On landing, I added some power at one point and the plane assumed a nose high attitude.

I don't know if this is related or not, but I can't get this plane to hold altitude on knife-edge either. I'm running the Endo setup (12x8 @ 4.6:1, 10 cells). Even with full rudder, which is about 45 degrees, it just descends on its side.

Thanks all.

~Dan
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Old Jul 30, 2003, 09:53 PM
17 years on RCG!
United States, NV, Las Vegas
Joined Dec 1996
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Hey guys!

I just got to fly my new E3D! You can see the info here:

http://www.rcgroups.com/forums/showt...hreadid=138120

I cant get it to hover with the Endo, and Im using the 16 ounce 3s4p Thunder Power 7800 mah packs (20-30 minute flight times per charge ). Im suprised since most can get it to hover on the Endo and 20-22 ounce 10 cell sub C packs!

Mine will only knife edge with full throttle and a good bit of speed. But even still, it does lose altitude. I think I just may need more power Ive got the Hacker hop up motor waiting for install, so when Im tried of the Endo, in it will go!

Jason
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Old Jul 30, 2003, 11:00 PM
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SchiessCo's Avatar
North Hills
Joined Nov 1999
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Dan - I would guess that you had too much down thrust dialed in. If your plane is trimmed for level flight under power, it would make sense that the nose would rise when you pulled the power off. Hopefully, someone with more experience will chime in.

Jason – How old is your Endo, and is the timing set per Gary’s instructions? Mine actually hovered quite well on the original set-up. It didn’t have a lot of excess power, but hovering wasn’t an issue. The real solution is to drop that Hacker in. The difference is amazing.

Pete
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Old Jul 30, 2003, 11:01 PM
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I think your knife edge problems might be that the CG is too far forward. You aren't getting much rudder authority. Move it back and it should fly fine.

As far as nose high on low throttle, I don't understand that if the CG is forward. All my 3D planes display this characteristic - E3D, Flip, Diablotin, FunWorld -- but the CG is to the rear -- eg: when you invert the plane it take 0 to very little down elevator.

-- Kyle
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Old Jul 31, 2003, 08:10 PM
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if your motor has some down thrust in it, and you trim it out for power-on flight, then when you turn the motor off (or lower the throttle) the plane will pitch up, since you had to add some up trim to compensate for the down thrust...
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Old Jul 31, 2003, 10:16 PM
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Thank you for all of the comments. I don't think I have any downthrust, but this is eyeballing it, not with an incidence meter. I think some more flights are in order with some inverted flight, different power settings, etc. One flight isn't enough to say for sure. Wish the weather would cooperate, but it's calling for rain for the next week.

Hope to determine the cause and post back.

Thanks,
Dan
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Old Jul 31, 2003, 11:18 PM
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From your photo and from the way the plane is designed, it doesn't look like you have any down thrust. When you can fly again, definitely fly it inverted and see how much down you need to maintain. It will give you a better idea of the CG and other issues.

BTW == are you running it with the brake turned off?

-- Kyle
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Old Aug 01, 2003, 10:09 AM
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I don't believe I am able to turn the brake off on my ESC, Great Planes C-50.

~Dan
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Old Aug 01, 2003, 11:10 AM
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Sounds like you have a touch of downthrust, or the cg is too far back. However, 4" from leading edge is only 1/2 inch or so behind the spar, and I'm running them well over an inch(almost inch and a half) behind the spar. My setups are just a tiny bit negatively stable with power off,..i.e. you have to fly the elevator quite a bit on landing, or it will pitch up and diverge from level flight (pitches up more and more,..negatively stable). First off, I'd check the thrust line compared to the wing incidence. If the removable wing changed the incidence a bit towards the positive side, then you effectively have downthrust. Generally pitch trim changes with power setting changes are thrustline problems. CG can play a small part too though, since elevator trim is changed with cg movement,..effectively the decalage is different to have it in trim power on,.. and that would create a pitching tendancy at different speeds.

sorry for the long digression,.. check your thrustline (compared to wing incidence, not fuselage).
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Old Aug 01, 2003, 11:13 AM
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Gary,

Thanks for the reply. Is there a way to measure incidence and thrust lines without a commercial incidence meter? If I continue to see this behavior, I may just try a shim here or there and see what happens.

Thanks,
Dan
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Old Aug 04, 2003, 07:58 PM
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Was able to get another flight in; it required a constant touch of down elevator to keep level during inverted flight. I think I'll come back with the CofG some more and see how it handles.

I've been staring at my main wing and I think it may ever so slightly have positive incidence relative to the motor thrust line and the horizontal stab. I'm going to try and prop the front of the wing down with some foam weather stripping at the front of the wing mount. Does this seem like a good idea?

~Dan
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Old Aug 06, 2003, 12:03 AM
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Vernon, BC, Canada
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I thought the wing looked +ve wrt stab on the pics. The eye can be deceived. Measure it out.
davidN
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