I am finishing my LT40 and read that the gaps in the elevators and ailerons should be filled with some tape or monocoat, If I have it right you bring the part in the up position and apply along the bottom edge. Am I right?

most do it that way to hide the covering or tape,method I use is if the gap isn't super large I use clear silicone in the gap and leave the control in neutral to dry,very fast and looks great.

I also seal the rudder

Do a search for the thread by Sharkey on "Sealing Hinge Line" for a complete discussion.

Dave Segal

Ailerons too

I do all the gaps. Helps to cut down on flutter and fuel seepage into the hinge line. Cut a piece about 1" wide and crease it tightly. Deflect the control surface fully and place the crease in the gap. Iron one side then the other. After a little practice, I learned to iron both side at the same time. I trim with a single edge razor blade. Use a NEW BLADE EACH TIME and be careful to hold the edge angle parallel to the surface so it doesn't dig into finished covering. Hit the edges with a hot iron and they'll disappear.

I don`t want togo against Sig,but I doubt if a LT 40 will go fast enough to give you trouble.That is if you don`t over power it. No doubt you will be using c.a. type hinges, they should be tight enough.Use 6 for elev. 3 for rudder and 8 for ail. Have built 2 from kits and 2 ARF`s all flew great. An LA 40 is a good power plant for this plane. Have a lot of good memorys of Greenville@ Donaldson AirForce base.Plus my wife is from there.She is up stairs now with her nose to the window,tears in her eyes watching it snow. good Luck AMA14958

HI big max 1935, sealing the hinge gap helps in the control and flight more than in flutter.

To John from Texas ,I have found that most new flyers have too much control.Hate it when I hear the xmtr. sticks rattle. Maybe the next model will have more performance, then seal gap.I have found the hardest thing to learn is when the plane is coming at you,and what to do.Oh well if we all did the same,we would`t be talking now. Do you want some snow?I have a little to spare. big max 1935, AMA 14958

It's really not a matter of speed, nor is it a matter of flutter. A sealed gap makes for a much better control surface.

When a surface is deflected (lets say downward) it creates a high pressure area under the surface and a low pressure area (or partial vacuum) above.

If the gap is not sealed, the air in the high pressure area gets sucked through to the other side. This not only decreases the effectiveness of the control surface due to lack of air control, but also due to the turbulence created by the air passing through. Now, factor in the fact that the gaps may be different on one aileron or elevator as opposed to the other (in fact, you can count on them NOT being identical), and you can see what havoc an unsealed gap can create. Sealing the gap keeps the air on the side it belongs. And regardless of speed, it will make your controls a lot smoother and more responsive.

Hi big max 1935,no thanks ,you keep the snow,raining,windy and in the thirties and fourties for the next week,back to building.I tell my students if they get confused when the plane is coming toward them move the aileron stick to the low wing of the plane,works every time and simple

MinnFlyer I give up. No matter what,I bet the thing will still fly. If the surfaces are sanded to a vee,and hinged tight,no sweat.I still say its just a trainer.I`m still trying to figure out howa bumble bee can fly? big max 1935 AMA 14958

The plane will fly probably sealed or not. But much better sealed. If you don't bother then you will never know how much better. I have had planes that wouldn't respond at all to aileron till I sealed the gaps.

Big Max, I tend to agree. Most of the time I'm the guy who says "Don't worry about it", but when it's something that can have a big effect on your controls, and it can be cured with 15 minutes of applying a strip of covering, Why not?