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Old Nov 05, 2011, 10:14 AM
Registered User
United States, CA, Livermore
Joined Jan 2005
129 Posts
Discussion
Hinging question

No matter what I do when I hinge and mount ailerons/rudder/elevator to a plane I get control surfaces that are stiff (high efforts). What is the trick to getting control surfaces that have minimal efforts (e.g., after mounting they give NO resistance to servos)? Should I use hinges with pins? Also what should the gap be between the control surface and let's say the rudder? I build small to medium wingspan planes (2-3' wingspan).
Thanks
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Old Nov 05, 2011, 10:44 AM
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ausf's Avatar
United States, NY, CENTRAL VLY
Joined May 2011
1,029 Posts
I've used the Tyvex envelopes from the Post Office with little resistance. Just make sure there is no glue or paint on them and use a few small strips as opposed to a full length.

I've even used thin monofilament in the past which worked well.

The last builds I've done were just packing tape on top covering. It has some spring to it, but not much resistance and I only use the linear UM Horizon servos.

In terms of gap, you want clearance but not slop. I apply the tape to the stabilzer, place the rudder at it's extreme travel (against the beveled edge), then press the tape onto it.
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Old Nov 05, 2011, 12:31 PM
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United States, AZ, Mesa
Joined Jul 2007
25,075 Posts
Ideally you should have no gap, but that is impossible with some hinging methods, so you make a little gap and then try to cover it with tape or fill it with welders glue. If air goes through the gap, there will be turbulence around the control surface and this can throw off the tracking of the plane, and cause wobbles.

My favorite method now of hinging foam surfaces is this woven-tape method. You don't have to cut a bevel, there is no gap, and it's very smooth moving. When done right, it adds some structural strength too.
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Old Nov 07, 2011, 03:38 AM
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Norway
Joined Feb 2010
602 Posts
Here is a great hinge using tape, I think it is what the previous poster referred to as 'wowen tape':
http://www.rcgroups.com/forums/showthread.php?t=1254977
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Old Nov 07, 2011, 06:41 AM
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flypaper 2's Avatar
Kingston, Canada
Joined Jun 2004
12,073 Posts
On the smaller planes I use Micropore. It's a light paper type tape. Obtainable at medical supply stores.

Gord.
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Old Nov 07, 2011, 10:36 AM
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C₄H₁₀'s Avatar
United States, AK, Fairbanks
Joined Aug 2009
12,256 Posts
I normally just use packing tape, but 3M's Blenderm medical tape is awesome stuff. Sticky as hell and very soft/flexible.

Plus, it's hypoallergenic

As for stiffness, there are a few things that cause it. For foamies, make sure that your control surfaces have bevels that are cut with a very consistent angle and ideally come to a sharp edge. Use a sanding block and fine-grit paper to get it nice and accurate.

When applying tape for a hinge, make sure the control surface and wing/stab aren't bent or flexed. This will cause a whole lot of binding.
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Old Nov 07, 2011, 10:50 AM
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Calgary, AB, Canada
Joined Apr 2008
2,150 Posts
Alot of hinging questions as of late.

Packing tape on EPS and balsa machines, like this:
http://www.rcgroups.com/forums/showp...72&postcount=4

Seals the entire hinge line, very free moving, never had an issue with them, however extreme cold weather may cause failure due to increasing brittleness.

Carey.
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Old Nov 07, 2011, 10:55 AM
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Tres Wright's Avatar
Forney, TX
Joined Mar 2002
15,165 Posts
I also use packing tape on smaller planes. First I bevel the stab (or wing TE in the case of ailerons) and the control surface, then cover them, then lay a strip of packing tape on my cutting board and cut a 1/2" wide strip of it. I put it on the airframe first, then hold the control surface in the fully deflected position and put it in place, then fold the tape over onto it, then burnish it down. This method will result in zero gap when the surface is deflected and about 1/16" gap when it's not deflected, but it's a "live hinge" (IE, the gap is closed by the tape). I then deflect the control surface the opposite direction and install two or three 1/2" x 1/2" squares of tape making sure to push it down into the bevel. This keeps the upper strip of tape from peeling off from the surface being exercised over and over again. The nice thing about packing tape is it sticks really well and it's nearly invisible.
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Old Nov 07, 2011, 11:02 AM
Build it, don't buy it
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Calgary, AB, Canada
Joined Apr 2008
2,150 Posts
With packing tape, a warm iron run over your hinge line will tighten up imperfections, and dramatically increase the tapes adhesion.
Temperature must be accurate though, there is very little tolerance between shrinking, and melting.

Carey.
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Old Dec 23, 2011, 01:24 PM
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United States, Mt, Kalispell
Joined Mar 2011
13 Posts
hey sorry for hijacking, i cant find a thread for this i have my first 120 edf or turbine jet and dont know what kind of glue to use to hinge it. a guy said to never use ca on them cuz they will blow apppart is he talking about the bulk heads or everything. i dont want the control surfaces to rip off at 200 mph so what glue do i use.
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Old Dec 23, 2011, 02:34 PM
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flypaper 2's Avatar
Kingston, Canada
Joined Jun 2004
12,073 Posts
Just found this adhasive/sealant at the local CTC or any automotive hardware should carry it. Something like hot glue or Goop but this stuff is thinner and more rubbery. The big plus is, it doesn't eat foam at all. Goop will eat EPS foam. Comes out white but dries clear.
It's called Pitcrews Choice and made by Permatex. Also works great for building foam planes. I use a small bit at the ends of the tape hinges where they start to come loose.
http://www.permatex.com/products/Aut...ve_Sealant.htm

Gord
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Last edited by flypaper 2; Dec 23, 2011 at 02:41 PM.
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