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Old Dec 07, 2012, 10:30 AM
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How Perfect does Perfect Have to Be?

I have a Champ that I just glued the tail feathers back on ....... and I notice that the Vertical Stabilizer is not exactly 90 degrees from the Horizontal Stabilizer.
My question is: how exact does this have to be, and if it is say 5-10 degrees off from 90 degrees, what will be the flight characteristics?
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Old Dec 07, 2012, 10:36 AM
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As long as it is not at an angle laterally (ie acting like a rudder) it will have NO effect.I have flown planes with an end wing panel missing, just by moving the wing further over the fuselage (in the days when I flew ic powered gliders with wings held on by rubber bands).It is the non-fliers who obsess about everything being perfectly square.Even they decide to fly with a non-perfect model after they have knocked their planes about a bit.
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Old Dec 07, 2012, 10:40 AM
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I agree with the above poster for the most part. It might not look as good as you'd like but probably won't affect flight characteristics all that much. Remember your dissappointment and try to get a better repair better next time. Go out and fly it!
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Old Dec 07, 2012, 12:39 PM
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You can trim out any slight error.
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Old Dec 07, 2012, 12:55 PM
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While what people are saying is true - small errors in alignment don't affect a plane like the Champ very much - I have seen cases where the rudder was bent in such a way that it didn't move correctly, put undue stress on the servo, and made the plane hard to fly because the rudder would 'snap' from one side to the other. As long as your rudder is moving smoothly, it should be fine, but be sure to check for that.
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Old Dec 07, 2012, 02:52 PM
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Originally Posted by Bob6831 View Post
I have a Champ that I just glued the tail feathers back on ....... and I notice that the Vertical Stabilizer is not exactly 90 degrees from the Horizontal Stabilizer.
My question is: how exact does this have to be, and if it is say 5-10 degrees off from 90 degrees, what will be the flight characteristics?
if 5-10 degreed, that is too much, or you will find the plane will lean one side.

Edmond
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Old Dec 07, 2012, 03:48 PM
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Originally Posted by Edmond Y View Post
if 5-10 degreed, that is too much, or you will find the plane will lean one side.

Edmond
Why would the plane lean to one side?
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Old Dec 07, 2012, 08:05 PM
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Originally Posted by alibongo View Post
Why would the plane lean to one side?
I had the same problem with the op, I fix the tail without have it true at a right angle, the plane keep move into the side that the stab leaned, it is not the rudder problem but surely I can tell because I did some not good enough.

Edmond
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Old Dec 08, 2012, 02:50 AM
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Originally Posted by Edmond Y View Post
I had the same problem with the op, I fix the tail without have it true at a right angle, the plane keep move into the side that the stab leaned, it is not the rudder problem but surely I can tell because I did some not good enough.

Edmond
From wikipaedia:
"The vertical stabilizers, vertical stabilisers, or fins, of aircraft, missiles or bombs are typically found on the aft end of the fuselage or body, and are intended to reduce aerodynamic side slip and provide direction stability. It is analogous to a skeg on boats and ships.

On aircraft, vertical stabilizers generally point upwards. These are also known as the vertical tail, and are part of an aircraft's empennage. The trailing end of the stabilizer is typically movable, and called the rudder; this allows the aircraft pilot to control yaw...
A V-tail has no distinct vertical or horizontal stabilizers. Rather, they are merged into control surfaces known as ruddervators which control both pitch and yaw. The arrangement looks like the letter V, and is also known as a butterfly tail. The Beechcraft Bonanza Model 35 uses this configuration, as does the F-117 Nighthawk, and many of Richard Schreder's HP series of homebuilt gliders."

The fin does not have to be at 90 degrees to provide stability and pitch control.I am sure an off-set fin would not cause noticeable control problems in a model, provided it is still vertical enough to act as a stabilizer, and the rudder moves freely.I am not advocating our putting planes together in a slap-dash way, but suggesting it is possible to worry too much about perfection.
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Old Dec 08, 2012, 11:55 AM
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The main effect for flying with a tilted vertical stabilizer is that there will be some pitch coupling with rudder input. At the extreme, with the vertical stab tilted 90 degrees, it would then be a horizontal stab and the rudder would become the elevator. The pitch coupling from one or two degrees of tilt would not even be noticeable in most RC planes. And since most RC flyers seldom, if ever, use the rudder while flying it really would have no effect at all.

Larry
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Old Dec 09, 2012, 01:29 PM
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Originally Posted by Lnagel View Post
The main effect for flying with a tilted vertical stabilizer is that there will be some pitch coupling with rudder input. At the extreme, with the vertical stab tilted 90 degrees, it would then be a horizontal stab and the rudder would become the elevator. The pitch coupling from one or two degrees of tilt would not even be noticeable in most RC planes. And since most RC flyers seldom, if ever, use the rudder while flying it really would have no effect at all.

Larry
True, except that the OP will have to use rudder since the Champ is a 3ch plane...

Withe the vertical stab 5-10 deg. off vertical from the horizontal stab, the plane will have a wider turning circle to one side (and keep the altitude a tad better while turning) and a narrower turning circle loosing altitude a bit faster in the other direction - the effects of the pitch coupling mentioned by Lnagel...

How I know? From countless hours of flying Champs in various states of repair
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Old Dec 09, 2012, 02:23 PM
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Even at 10 degrees the change should not be noticeable - it is a model with a 22 inch wingspan, not a fast jet!
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Old Dec 09, 2012, 05:58 PM
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Originally Posted by alibongo View Post
Even at 10 degrees the change should not be noticeable - it is a model with a 22 inch wingspan, not a fast jet!
You better know what you are talking about, try use a degree measure to see how large is ten degree and make your plane the same way and go fly and see how it flies, we are seeking true informations to learn with. As the other member said, one or two degree may not affect much but certainly not ten degree.

Edmond
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Old Dec 09, 2012, 10:20 PM
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I agree we are looking for accurate information- I shall indeed test this out in the next few days and report back!Look at this tailplane, flew just fine.I shall glue it on straight and see if there is any noticeable difference:
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