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Old Sep 13, 2010, 11:23 AM
Medicinal Foam User
Wilfor's Avatar
150 mile house B.C. Canada
Joined Jan 2010
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Ryan i would just fly it myself . If your really worried about it you could cut the seam and then reglue it , take a little off each side so the wing would be a little narrower but it wouldnt be a big deal .
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Old Sep 13, 2010, 11:46 AM
Slipping the Surly Bonds
dz1sfb's Avatar
Attica, MI
Joined Dec 2006
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Quote:
Originally Posted by doughpat View Post
1.) What would the effect of excessive dihedral? (I'm hoping just a really REALLY stable plane...but I fear nose-diving on turns)

2.) Any ideas on how to fix it? (Depron-esque foam)
1.) It will require less rudder to turn. It may even feel roll sensitive. Rudder rolls will be easy.

2.) Its pretty easy to make a new wing, but I would just fly it as Wilfor suggests. Sounds like too much work to tear it apart, but could be flattened out some by cutting the centerline foam joint and installing a filler piece of foam and retaping.

Ken
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Old Sep 13, 2010, 03:40 PM
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Freddie B's Avatar
Omaha Nebraska
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Originally Posted by doughpat View Post
1.) What would the effect of excessive dihedral? (I'm hoping just a really REALLY stable plane...but I fear nose-diving on turns)

2.) Any ideas on how to fix it? (Depron-esque foam)
Ditto, fly it. It will probably just appear to 'jump' into a bank, and exit quite quickly, with a little wing rock, but be VERY stable. Not a bad thing for those students! The old Wattage Tubby Cubby had excessive dihedral and flew fine, jut a little 'jumpy'.

I'm sure a second wing is coming soon too, how could you resist tinkering with different setups!

Fred
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Old Sep 13, 2010, 03:50 PM
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Omaha Nebraska
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This is how I did a non-stearable tail wheel. Mainly wanted to show how a long piece of popcycle stick gives a large gluing area, and it has never even started to rip off, or tear at the tail area. Just make sure the plastic on the FFF is removed in the glue joint area.

I'm doing 30-40 touch and goes everyday too!

Another tip is to poke holes in the foam with a toothpick before gluing, giving the glue areas to create 'glue teeth' and it will really be anchored!

Did a stearable tailwheel on another, conventional in the rudder, and added a joiner to the elevator. Try to shoot some pictures later.........

Fred
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Old Sep 13, 2010, 05:19 PM
AKA Don
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Troy, MI USA
Joined Dec 2002
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Originally Posted by doughpat View Post
Well, I don't know how it happened, but it did: I've got waaaaay too much dihedral in my UC 33 wing. It's about 2.5" per wing (i.e. almost 5" when I lay one end down flat). Yikes. Unfortunately I've already glued it, taped it, and reinforced it with CA hardened balsa dowels on the LE and TE. So:

1.) What would the effect of excessive dihedral? (I'm hoping just a really REALLY stable plane...but I fear nose-diving on turns)

2.) Any ideas on how to fix it? (Depron-esque foam)

Nose diving turns (spiral instability) are caused a lack of dihedral. With too little dihedral once you get the plane into a turn it is difficult/impossible to get it out again. Too much dihedral should just reduce lift, which will increase the speed needed to fly, and make the plane super stable at neutral rudder and roll sensative to small rudder movements. Not a nose dive but more of an axial roll.
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Old Sep 13, 2010, 05:21 PM
Crash it first, Then fly it
Griffindor's Avatar
The Big Apple
Joined Jul 2008
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the Problem now is that my dad won't let me buy foam, so I'll most likely have to make some cross sections of an encambered wing, reinforce with CF, and wrap wall paper over it. It'll be a mix between foam and balsa planes.



Maybe if I show him cheap store bought foam, he would approve.
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Old Sep 13, 2010, 05:26 PM
Crash it first, Then fly it
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I'm an officaill AMA member now!! Got to renew it soon though...
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Old Sep 13, 2010, 05:27 PM
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I'm an officaill AMA member now!! Got to renew it soon though...
me too.
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Old Sep 13, 2010, 06:12 PM
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Thanks all! Will fly it as is. And yes, I am definitely looking forward to throwing different wings on there. Really eager to try the KF wings.

Any preferences on which side of the control surface to mount the control horns onto?

Also--I'm using that nice blenderm fiber tape for a full length hinge. I put it on the flat side (the one without the bevels cut into it) of the rudder and elevator. It seems plenty secure. Do I need to put another piece into the bevelled cut? (I realize that I'd need to extend the surface so that the tape goes "into" the angle) Seems like an unneccessary bit of resistance to give the servo.

Thanks as always, all! Wonderful group.
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Old Sep 13, 2010, 06:14 PM
AKA Don
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Troy, MI USA
Joined Dec 2002
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Originally Posted by Griffindor View Post
the Problem now is that my dad won't let me buy foam, so I'll most likely have to make some cross sections of an encambered wing, reinforce with CF, and wrap wall paper over it. It'll be a mix between foam and balsa planes.



Maybe if I show him cheap store bought foam, he would approve.
Most dollar stores sell foam sheets covered with paper for $1 per sheet. Best to remove the paper to save weight, but the foam is very usable.

doughpat..I have used one sided blenderm hinges on many planes, without any problems.

I did wonder about your use of the word Fiber tape as my blenderm has no visible fibers.
Don
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Old Sep 13, 2010, 06:21 PM
Addicted to building...
Freddie B's Avatar
Omaha Nebraska
Joined Feb 2006
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Beg some contractor types for some excess, or scrap foam, after telling them what you want it for. Maybe put the word out with anyone you know that works retail. Or ask that nice hobby shop people to let you put up a flyer asking for some 'scrap foam for young person aspiring to be an RC aircraft builder'!

I'd donate a few sheets to your cause, but we live too far away. Got to be hundreds of modelers in your area that like to help new builders become old builders like me!

Good luck.

Fred
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Old Sep 13, 2010, 06:41 PM
Medicinal Foam User
Wilfor's Avatar
150 mile house B.C. Canada
Joined Jan 2010
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Quote:
Originally Posted by doughpat View Post
Thanks all! Will fly it as is. And yes, I am definitely looking forward to throwing different wings on there. Really eager to try the KF wings.

Any preferences on which side of the control surface to mount the control horns onto?

Also--I'm using that nice blenderm fiber tape for a full length hinge. I put it on the flat side (the one without the bevels cut into it) of the rudder and elevator. It seems plenty secure. Do I need to put another piece into the bevelled cut? (I realize that I'd need to extend the surface so that the tape goes "into" the angle) Seems like an unneccessary bit of resistance to give the servo.

Thanks as always, all! Wonderful group.
Watch this
How to Cut a 45 bevel and make a tape hinge (4 min 28 sec)
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Old Sep 13, 2010, 06:58 PM
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Wonderful video....thank you Wilfor. But just out of curiousity, what would happen if you only taped one side of the hinge with a full length piece of tape? Potential sloppiness? Maybe it will come loose?

Tips on whether to put the control rods on a certain side of the elevator/rudder? I'm thinking I'll put the elevator control rod/horn on the top of the elevator, so that it's protected from the ground, but the rudder one....hmm....
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Old Sep 13, 2010, 07:23 PM
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Ontario, Canada
Joined Apr 2010
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If you are using piano wire control rods, they work better in tension than compression under loads. For most control surfaces this is not a big deal... but with the elevator I prefer to have mine on top.

If you place the horn on the bottom of the elevator, the pushrod wire will bow under compression (ie pulling out of a high speed dive) and you may lose elevator authority. How much depends on the aerodynamic forces involved and how the pushrod is supported.

I have 2 models that have the elevator control horn on the bottom and they do not have issues... but they are designed for it. One with stiff CF pushrods and the other is an RTF that is very lightly loaded and has well supported pushrod tubes that do not bend easily.
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Last edited by philipa_240sx; Sep 13, 2010 at 07:29 PM.
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Old Sep 13, 2010, 08:06 PM
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Joined May 2009
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More questions (now I see why this thread is 1000+ pages long...):

Which way should the motor turn? (need to know before I make the motor control wires semi-inaccessible)

I reinforced the LE and TE with a balsa dowel. Should I sand the edge into an angle, or leave it round?

Hoping for maiden flight tomorrow!
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