material to seal control surface gaps
 

My hanger 9 Pulse XT is almost ready! Will maiden next week. I would like to seal the aileron/elevator gaps, actually not much...very very close fit with the beveled edges. What would be best.....scotch tape or better if I got some Ultracote and ironed on? Any tips on applying either? Should I also apply to the rudder?


Thanks!

RE: material to seal control surface gaps
 

either would be fine...

I use covering to match the aircraft

RE: material to seal control surface gaps
 

Use a long strip of covering (whatever you used to build it, or if it's an ARF, whatever they used to build it). You can use clear or a color to exactly match so it does not look obvious. The length should be slightly longer than the gap you intend to hinge.

Make the width slightly smaller than the inside width (both sides) that you are going to fill.

Fold it in half lengthwise, exactly (or as close as you can get it) down the center. Then remove the backing. Place it in the groove with the surface flexed as far on the opposite side as you can get it, then fit the covering down so that it is completely flush with the gap and evenly spaced on both sides.

Use a small iron (there are both regular sized irons and a smaller trim size iron) and seal it starting at the middle and work your way out making sure to keep the heat even on both sides while pushing down into the hinge line to make sure it goes all the way into the gap. Do both sides (of each aileron.... remember, you started in the middle) then both wings the same.

It is not necessary to seal the elevator hinges nor the rudder hinges unless the gap is like an eighth of an inch or something..

You don't have to do the top and the bottom of the aileron hinge, by the way, just one side. You can probably guess that the bottom would probably be best so that any mistakes are not immediately obvious to a casual observer.

DS.

RE: material to seal control surface gaps
 

Thanks CGRetired...appreciate the step-by-step. :) I didnt like the dull finish of the scotch tape...thought it stood out too much. Will use the Ultracote. :)

RE: material to seal control surface gaps
 

Oops...one more question....can adhesive backed trim sheets be ironed, heated to fit in tight places?

RE: material to seal control surface gaps
 

Why seal them if they are a close fit?
Do certain models need to have them sealed or is this just something that is done if the gap is too much?

RE: material to seal control surface gaps
 

From what I understand....when the control surface is flexed...air streams will find their way between the wing and control surface. At high speeds causing flutter. Also able to get better aerobatic response forcing the air to flow along the entire width of the wing from leading edge to trailing edge without interruption(for lack of better word). This is what Im told by the 2 guys at my field that fly 35% gas Edge's and 30% gas Yaks; who have been flying for over 20 years. They've pretty much taught me how to fly after my initial training sessions. I owe them alot. Thanks Drew and Alan!

RE: material to seal control surface gaps
 

Pretty much trying to get the best performance out of the plane and as a preventative measure against flutter before it happens.

RE: material to seal control surface gaps
 

ro347,
Air flowing through the gaps in your plane usually isn't the cause of flutter. But instead the air flowing through the gaps will decrease the preformance of you plane as well as decreasing the effectiveness of control surface on the plane.

Flutter is usually caused by a control surface not being properly secured and allowed to move with the plane in flight. This can also happen if parts of the plane are loose.

Ken

RE: material to seal control surface gaps
 

Well if thats the case I stand corrected. Thank you for the lesson. In my mind I thought the air traveling through the gap at high rate would cause turbulance around the control surface ...eventually leading to the possibility of loosening the tightness of the hinge etc. Is this not a possibility?

RE: material to seal control surface gaps
 

Not really. The biggest problem is loss of effectiveness. You have to go back to how planes fly. Air flowing over the wing causes a pressure difference between the two sides of the surface, thus creating lift. When air flows through the gaps it changes this pressure differences which effects the flight of a plane.

I guess over a long time it could possibly cause problems and loosen the hinge up. But I have several planes 8+ years old that don't have the gaps sealed and the control surfaces are still solidly connected. The biggest problem I have observed is that it decreases the performance of the plane.

Ken

RE: material to seal control surface gaps
 

Thanks RCKen....


Should we be sealing both sides of a surface or only the bottom?

RE: material to seal control surface gaps
 

There was an article in the July issue of Model Aviation on hinging by Jason Noll where he spoke about gap sealing. He said it helps control surface to be more responsive, more efficient and lowers the risk of flutter. The article gives great step by step instructions for the installation of hinge points and gap sealing.

Scott

RE: material to seal control surface gaps
 

Wouldnt sealing the rudder improve knife edge performance if the plane is capable to begin with?

Excuse my elementary questions...but Ive learned alot on here.

RE: material to seal control surface gaps
 

Thanks Saramos....I will make sure to take a look. If i get a chance I will try and scan and post it here for reference.

RE: material to seal control surface gaps
 

You do either way, seal one side or both. I prefer to seal both sides so the hinge line is completely sealed. This will prevent any dirt or debris from building up in the gap between the hinge and the plane.

I explained how to cover hinge gaps in my LT-40 build thread. You can find the descriptions at:
[link]http://www.rcuniverse.com/forum/fb.asp?m=5399213[/link]
and
[link]http://www.rcuniverse.com/forum/fb.asp?m=5589251[/link]

Hope this helps

Ken

RE: material to seal control surface gaps
 

Now that's service...I can always count on RCKEN! Cant get any better than that....ummm unless you want to do it for me. HA!

RE: material to seal control surface gaps
 

Good point, Ken.. about sealing both sides. It really isn't that much more work, only a few minutes more, and it's done.

I didn't realize the difference sealing the gaps made until I did it. Rolls are much more crisp and precise as are turns and any other maneuver requiring ailerons. The pattern guys (mainly Ron and Dave Lockhart) got me to do mine.

Dick.

RE: material to seal control surface gaps
 

The glue in scotch tape is easily dissolved by glow fuel.

Many places sell Blemderm ( spelling ? ) which was developed for wounds. Tower and Horizon both sell it as hinge sealing tape.

It works fairly well.