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Snap Roll Question

Old 12-31-2001, 05:30 AM
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Default Snap Roll Question

I'm flying the Godfrey 1/4 scale Laser 200 and it has a Zenoa G23 engine with a 16x8 MA prop. At about 1/2 throttle when I pull up going into a loop the plane snap rolls out. Can anyone tell me what I need to do to correct this.

My first thought is that it's nose heavy so have moved the battery pack back about 4 inches. Is this the right direction to go?
Old 12-31-2001, 05:50 AM
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Default Snap Roll Question

Describe the direction of the rollout.

Describe how your pulling up into the loop and how much deflection your using to accomplish the upline. Are you using to much elevator throw?
Old 12-31-2001, 08:15 AM
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Default the snap....

Sounds to me like to much elevator too. Not that it's to much on the plane, but possibly the input for your manuever. I've seen similar traits before, and what it was was mere technique, and it could be what your doing is instigating a snap by just to much elevator, and not enough power to pull through.

Try it using the same power setting, and a slight nose down heading to build a little speed, then feed elevator very smoothly. This technique will get most if not all planes to carry through a loop very easily. If this works, it might shed light on alot of other areas for you.

You didn't mention the weight of your plane, what might be interesting is to figure your wing loading and see where it stands, and figure out your power-to-weight ratio's and see if your G-23 is up to the task. The 23 is not quite a big engine, and put on a plane that could be borderline big, well, a bit of research as I said could be interesting, and a learning experience. Also you while balancing your plane, you want to check the lateral balance as well. Take all advantages you can. Keep us posted. Good luck.
Old 01-01-2002, 02:24 AM
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Default Snap Roll Question

The plane weighs 11 pounds, it's the Lanier kit designed by Godfrey.

Maybe this will help, it will snap doing an imillmen(?) faster than it will doing a loop. My loops are big and round as I have smoke and they look good.

With the plane coming at me it will snap rolling to the right. I call it a snap and if I was to go up high and enter it would do a great looking spin.

One other thing, when landing I have to keep the speed up or will run out of elevator.

The G-23 will pull this plane vertical as far as I want it to go. I look forward to your comments.
Old 01-09-2002, 06:53 AM
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Default Snap Roll Question

I would just leave it be,cause 1 of the advanced Imac sequeces move is half loop w/ 1/2 neg snap, Just kidding!!! do ya ever get up to little rock for the big bird or smalls?
Old 01-09-2002, 07:55 AM
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Default Snap Roll Question

Were does the model balance at? Laniers recommendation for CG?

Sounds like nose heavy to me.

The G-23 weighs 3-1/2lbs. plus... This model should weigh in at 9lbs... It was designed around a 120 size four-stroke @ 2lbs.

Were are the servos located for elevator and rudder?

Move the battery back, toward the tail of the plane.

How much elevator deflection do you have?
Old 01-09-2002, 05:31 PM
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Default Laser 200

Been flying one all last summer. Has an MDS 1.48 in it. Landing were dicey until I balanced it by pulling the wings out a bit form the fuse and looped a string around the wing tube. Added about 3/4 oz to tail to get the plane to hang level. Now it just floats in.
You might try a little expo on the elevator to soften the intial response to the stick movement. I have not noticed any unwanted snapping tendencies in my plane, but I fly most of the time on low rate which is more than enough for non-3D type aerobatics.
Old 01-09-2002, 06:30 PM
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Default Warped wing?

Does the plane always have a tendency to snap in the same direction all the time? When slowing the plane down in straight and level, does it have a tendency to drop a wing...and always in the same direction?

If so, you might have a warped wing, or aileron that is warped causing the plane to tip stall. If the wing is warped at the tip as the wing approaches a stall, the tip stalls first, and it will snap in that direction. When you are adding elevator and increasing G's you are raising the stall speed, and if it has tip stall tendencies, a snap is the result. Depending on the design of the wing some planes have a tendency to tip stall and others don't. I don't know anything about your particular plane to know if it is sensitive to this or not.

Bill
Old 01-09-2002, 08:12 PM
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Default Snap Roll Question

So many questions I'll have to think each one out. The plane always snaps to the same direction.

I've moved the 1500 mah batteries back 4 inches and the elevator, rudder servos are installed just below the front of the stab.

The elevator deflection is not excessive. One guy told me I need expodential in the elevator, tried it and didn't like the way the plane took off. It took a long time to get airborne.

The plane seems to run out of elevator when I land as it doesn't float in I have to power it in. That's why I'm thinking it's nose heavy.

I went to the Big Bird flyin at the sod farm last year and have gone to the SMALL in Maumelle for the last 4 years.

Right now it's not right for flying so have time to check the balance and move things around.

Thanks for all the input and keep it coming.
Old 01-10-2002, 04:25 AM
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Default Snap Roll Question

I hope these guys solve your problem m8, just to let you know small probably won't be in maumelle this year cause there is a bank on our driveway, new field should be ready by june, its gonna be at burns park off of I-40
P.S. can you hook me up w/ some good hunting?
Old 01-10-2002, 05:57 AM
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Default snap, maybe elevator halves?

Just another thought. Something you might look at. If both elevator halves are not move together, you could get a rolling effect. Eye ball them with no load and see if they track the same. Then add some load (finger tips, or some little weights) and see what they do.
Good advise in the other posts. Maybe a combination of several little troubles.
Good luck.
Wyatt
Old 01-10-2002, 04:46 PM
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Default Snap Roll Question

Well, just another thought or two-- How carefully did you set the incidence of both the wings before glueing those little disk to the fuse side for the wing dowels? And how good a fit are those dowels in those little disks?
I had to epoxy pieces of brass tubing into those disk to keep my wings solid. They vibrated and rattled at idle, and must have flapped aound pretty good in flight.
Old 01-18-2002, 03:18 AM
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Default Snap

WSPUR has a good point. We had a flyer at our club that had a similar problem with a .90 size cap. He had a weak/slow servo on one elevator half. A god going over with an incidence meter wouldn't hurt either if you haven't already done so. Your welcome to borrow mine. I'm right on your way to Franks.

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