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Old May 20, 2007, 08:37 PM
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VRflyer's Avatar
Montreal,Canada
Joined Feb 2002
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Discussion
Why the CG of my Easystar have moved forward?

In my Easystar, if I balance it at 3inc. behind leading edge of the wing near the fuselage, my planes goes immediately nose high when I hand launch it, do a brief loop. and crash. To correct the problem, I had a lot of weight in the nose of the planes.
Presently the planes is balance when the CG is at 1.5inc, this a lot of difference than manufacturer suggest.
In my first Easystar, my CG was normally locate.
Why this time the CG moved forward

P.s. I tried yesterday my Cap (after repaired ), I added weight on the nose liked suggest by Andres, and I landed the planes easily. I did not fly it FPV. So now the planes look ok
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Old May 20, 2007, 09:17 PM
gwh
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Fort Worth, Texas
Joined Dec 1996
1,608 Posts
Take a close look at the wing, tail, and motor incidence angles. It sounds like one or more of these is off.

BTW, I really like the FP videos that you have posted. I am slowing accumulating the parts that I need to give it a try.
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Old May 21, 2007, 05:36 AM
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Elmhurst, NY (Queens in NYC)
Joined Apr 2004
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Is there any difference in the thrust line?

It is really hard to imagine something that came out of a mold being radically different but maybe the wings were stored badly and are deformed slightly.

That's one of those things that doesn't make sense. I'd love to see the airplane and try to figure it out, but on-line diagnosis is all just wild guesses.

When you get it figured out please post what the problem was, I am very curious. I know it is nothing obvious since you have been flying RC for a long time and would probably spot things that other people might not notice.

Pete
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Old May 21, 2007, 09:00 AM
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Madrid, Spain
Joined Dec 2004
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Hi

It´s hard to say without seeing the plane flying. Could be any incidence like gwh said, but usually the motor incidence is the easier to set up wrong, and if the Hyperion motor is hotter than the E-flite, probably need a bit more incidence.

Sometimes setting up a plane correctly is a pain. What I usually do is firstly look for the correct CG comparing the nose behaviour without motor at different speeds, that´s trimming the plane at slow-medium speed and then do the well known dive test, but always without motor to avoid motor incidence influence, just in case it´s not correct.

Then compare the behaviour between motor off/WOT. For example after a dive with motor off, level the plane for a hands off level flight, and hit throttle to WOT, should remain leveled if the motor incidence is ok.

But if the incidence of the wings or tail is wrong, you can go crazy doing tests and never be able to set the cg correctly. Moreover a plane like the EZ, with an airfoil that is not symmetrical, produces different lift depending on the speed, so you will never have a completely neutral behaviour and will be even harder to know what´s wrong.

Sometimes I go crazy to set all of this up, and as Pete says, an on-line diagnosis is even harder.

Good luck


PS: glad to see the Cap now is easier to land, I´m looking forward to see another video

Andres
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Old May 21, 2007, 12:33 PM
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United States, KY, Hebron
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can't you figure out where the CG is by balancing it?
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Old May 21, 2007, 02:01 PM
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Montreal,Canada
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Ok I got it!

In fact I had two problems. The first one was the motor incidence. Normally the motor axe is parrallel to the fuse axe, but in the easystar, we can see the motor should be install with angle. Like in my first easystar, when I moved throttle up, the planes raise to the sky. It's look normal because the planes is a motorize glider, so I should use motor only to gain altitude. I prefer the motor to be parallel with the fuse, so when I apply power, it remain level. I changed the motor angle the first week and it correct the first problem.

I still had to put 2 ounce in the nose to fly it, and the new cg was 1.5 inc in front of the manufacturer cg. I tought the stabilser was wrongly install, I did not remember anything in the instruction how to install it so I glued it where I tought it goes... WRONG

I check again instruction to see if I miss something, and I saw the drawing showing the angle of the stabilser should have. The last year easystar was littly better, by luck, but this one have the stabiliser with too much incidence.

After crashing many time on the nose, and now completly ruin the stabiliser by ungluing it, it time to order Easystar 3 ( Easystar 2 life was short, but intense)
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Old May 21, 2007, 03:25 PM
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Canada, BC, Duncan
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Oh well I guess Easystar2 is great for spare parts! Who knows maybe use the wing and add it to the Easystar3? Turn it into a Easystar Biplane? http://www.rcgroups.com/forums/showthread.php?t=666405
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Old May 21, 2007, 05:15 PM
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Easystar biplane
I will kept it for spare part. It still fly, I will use it until the new one arrive.
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Old May 22, 2007, 10:15 PM
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Yeah you are right Denis. The Easy-biplane was a crazy thought
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Old May 23, 2007, 05:22 AM
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Quote:
Originally Posted by JMSTECH
Yeah you are right Denis. The Easy-biplane was a crazy thought
Not that crazy, someone in the UK flies one. I saw it on the Aerial Photography forum. Well, that doesn't prove that it isn't crazy, but at least it is a workable idea.

Pete
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Old May 23, 2007, 02:21 PM
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Montreal,Canada
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Quote:
Originally Posted by JMSTECH
Yeah you are right Denis. The Easy-biplane was a crazy thought
I don`t think its crazy, I love it very much. But why do it again since another one have done it
It will be my third easystar. Triplane as not been done yet
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Old May 23, 2007, 03:16 PM
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So maybe .... a chance we will see one in use for FPV
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