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How to remove dihedral from wing center section?

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How to remove dihedral from wing center section?

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Old 11-29-2005, 04:16 PM
  #1  
Ernie Misner
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Default How to remove dihedral from wing center section?

I want to build my 4*60 ARF with zero or much less dihedral. Does anyone have any good ideas how to easily go about that? I keep thinking of installing an angled shim in the center section, and building a new hardwood joiner without the angle in it.

Thanks for any input!

Ernie
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Old 11-29-2005, 05:01 PM
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oscar2005
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Default RE: How to remove dihedral from wing center section?

your idea will work but with no dihedral the wing will look like it is drooping down.even patter ships have dihedral either by the way the rips are tapered and having the top of the wing flat due to the thinner tip ribs there is dihedral.most patter type designs have abot 1/2 underthe tips.while sport plans have about 1 1/2 to 2 inches..a good starting place for a sport aircraft is to take the span devide by ten then devide by 2 that is total dihedral so on a 60 inch wing it is 3 inches.just remember as you decrease dihedral the airlerons become more effective and the rudder less effective.good luck
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Old 11-29-2005, 09:19 PM
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Default RE: How to remove dihedral from wing center section?


ORIGINAL: Ernie Misner

I want to build my 4*60 ARF with zero or much less dihedral. Does anyone have any good ideas how to easily go about that? I keep thinking of installing an angled shim in the center section, and building a new hardwood joiner without the angle in it.

Thanks for any input!

Ernie
That will work. Cut your new brace from hardwood ply. The shim can just be a piece of balsa that's been shaped and sanded to fit.

I'd leave a little dihedral in it. Maybe 1/2"--1" under 1 wingtip. It'll look silly without any dihedral and you won't really notice the difference between 1" of dihedral and 0 dihedral. But, you WILL notice the difference between stock dihedral and 1" of dihedral.
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Old 11-30-2005, 02:52 AM
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Default RE: How to remove dihedral from wing center section?

Thanks for your ideas guys. Oscar, the 4*'s don't have tapered ribs, just maintain the same thickness section all the way out. Same deal with the wing on my Ultra Stick which has zero dihedral. The difference though, is that the U. Stick is a high wing plane and the 4* is a low wing plane.

Rcpilet, being a low wing plane, that's a good idea to leave a little dihedral. I like your idea of making a balsa shim. I kept thinking it would have to be harder wood for some reason.

I like the way my 4* 40 flies with stock dihedral, but I think it would be a bit more fun and stable during inverted manuvers with less dihedral.

Ernie
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Old 11-30-2005, 10:58 AM
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Default RE: How to remove dihedral from wing center section?

Hi!
It won't be more stable!...practice is the only answer
Just keep the dihedral as it is! It isn't worth the trouble altering the dihedral.
Sorry!

Regards!
Jan K
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Old 11-30-2005, 01:45 PM
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Default RE: How to remove dihedral from wing center section?


ORIGINAL: Ernie Misner

Rcpilet, being a low wing plane, that's a good idea to leave a little dihedral. I like your idea of making a balsa shim. I kept thinking it would have to be harder wood for some reason.

I like the way my 4* 40 flies with stock dihedral, but I think it would be a bit more fun and stable during inverted manuvers with less dihedral.

Ernie
The dihedral brace is going to give you the strength that you need for the wing. You can use some tapered aileron stock and fit it down in the gap on the top.

If you get everything ready and glue it all up at once, you'll get a better joint.

If you glue the brace in first and then glue the tapered pice in on the top--you won't get as good a joint.

The reason is because when you do it all at once, all the glue will dry at the same time and it will all be covering everything at once.

Wet epoxy doesn't make a very good bond to dried eopxy.

Changing the dihedral will make is LESS stable, but more fun.
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Old 11-30-2005, 02:11 PM
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Default RE: How to remove dihedral from wing center section?

Why do you want to remove the dihedral? Have you flown a 4*60? You might be attempting something that is a lot of work and unnecessary.

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Old 11-30-2005, 03:48 PM
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Default RE: How to remove dihedral from wing center section?

Forget the looks, a low wing plane with no sweep needs dihedral to counter adverse roll with rudder. Just as a high wing plane with no dihedral will roll in the direction of the rudder, a low wing plane with no dihedral will roll opposite to the rudder. Dihedral counters this roll in a low wing plane and anhedral counters it in a high wing plane.

The best thing you can do for a 4*60 is keep the stock dihedral, but remove one rib from each side and increase the size of the rudder by an inch in chord. And use a .91 for power, of course. If you are really feeling frisky, remove 2 ribs from each side.
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Old 12-01-2005, 02:58 PM
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Default RE: How to remove dihedral from wing center section?

>>> The best thing you can do for a 4*60 is keep the stock dihedral, but remove one rib from each side and increase the size of the rudder by an inch in chord. And use a .91 for power, of course. If you are really feeling frisky, remove 2 ribs from each side. >>>

Interesting thoughts guys! Yes, it sure is a very low wing plane as is my 4* 40. Do any of the zero dihedral highly aerobatic planes such as the Yaks or Extras have such a low wing, or are they all in the center?

I just may go with your plan Ed!

Ernie
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Old 12-01-2005, 03:24 PM
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Default RE: How to remove dihedral from wing center section?


ORIGINAL: Ernie Misner

>>> The best thing you can do for a 4*60 is keep the stock dihedral, but remove one rib from each side and increase the size of the rudder by an inch in chord. And use a .91 for power, of course. If you are really feeling frisky, remove 2 ribs from each side. >>>

Interesting thoughts guys! Yes, it sure is a very low wing plane as is my 4* 40. Do any of the zero dihedral highly aerobatic planes such as the Yaks or Extras have such a low wing, or are they all in the center?

I just may go with your plan Ed!

Ernie
Ed has it right on the nose. In the case of your 4-Star, leave the dihedral in, unless you are prepared to sweep the wings, or add winglets -- & why bother with all that mess.

If you just can't leave it alone, remove the dihedral & turn it into a mid-wing, then lower the horiz stab while you're at it ---- nothing to it.

Better yet, turn the wing/fuse assembly upside down & rebuild the turtle-deck on the new top-side -- then you will have anhedral, if that turns your crank.

Lots of interesting choices, but leaving it alone is as good as any of them.
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Old 12-01-2005, 04:45 PM
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Default RE: How to remove dihedral from wing center section?

>>> but leaving it alone is as good as any of them.>>>

Ahhhh, no fun! "Today" I like Ed's plan a lot.

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