In almost every source for model aerobatics you'll find this tip: Seal your control surfaces gap.
My question is simple. Is this realy required for? what is its importance in a pattern plane?

Thanks

Yoav

It is very important. If the gaps are too large between the control surface and the wing, the air can pass between the two, and actually reduce the wing and control surface effectiveness.
I built a Stevens Aeromodel Edge 540 awhile back, was my first aerobatic plane, and the first kit I had built in many years. Everything went together very nicely, their kits are excellent quality. When I got finished, there was about a 1/16" gap between the wing and aeilerons. I didn't think too much of it, and flew the plane anyways.
It flew pretty decent at speed, but when I tried to come in for a landing, the disruption in airflow over the wing due to the wide gaps made the plane just about uncontrollable at slow speeds. I was lucky to get her down in 1 piece.
I let one of the other pilots at the field fly it, a VERY experienced pilot, I might add, and it took him 4 approaches before he was able to land it safely.
We looked the plane over, and he noticed the gaps at the aeilerons. He gave me some hinge tape, and I sealed the gaps. The plane was absolutely amazing after that, flew fantastic, and landed smooth as silk.
It makes a difference, seal your gaps. You will be glad you did.

Interesting.

Jason Shulman does NOT (according to his comments) seal his hinge lines.
Not exactly a rank amateur at Pattern.

You have to take into consideratio the type and caliber of aircraft he flies. I'm sure he's not flying the run-of-the-mill ARF that the majority of new pilots are flying. If your plane has a control surface design that completely shrouds the control surface seam, then no sealing would be neccessary. Also, if your control surface gap is very minimal, sealer would probably not be of much help.
However, if the plane you're flying has enough of a gap for air to pass, it is recommended to use sealer.
To each his own, i'm not telling you to use it, I just know from my experiences, and advice i've been given from more experienced pilots than myself, that it does make a difference if your gaps are less than perfect.

I look at it like this..... It certainly can't hurt to seal the gaps, but if the gaps are too wide, it will have detrimental effects on flight. So......if it can't hurt, but MIGHT help, why not seal the gaps?

I noticed a big difference on one of my 3D planes. I was having a big problem with wing rock when in High alpha flight. I did some reading and figured it couldn't hurt to try hinge sealing. I was already re-hinging the plane at the tme anyway. To my amaziment almost all the bad habits the plane had were gone. There was just enough airflow in the gap to disrupt airflow over the wing. Anyime you disrupt the laminar flow of air over the wing it will kill lift. It really does depend on your model though. I have a pattern style aircraft that I flew forever without the hinges sealed. When I started messing with 3D I went back and resealed everything and it really did not make that much of a difference. It s a GP Reactor BTW. I think it is very aircraft dependent. Some hinge designs do not need it. If I were you I would give it a try sealed and unsealed and see wat you like best. Good Luck!

So can someone give me an explanation on how to seal the gap with hinge tape? Do I tape both top and bottom? Do I fully delfect the control (elevator, aileron etc) and then apply the tape??

Newb question I know, but I had some flutter on the elevator of my Hyperion Yak 25e which may have contributed to a stab/elev failure (amongst other things). I think sealing that surface will help. I was able to land the plane with half a tail!

Mav, what I do is seal the bottom surface. You don't need to do top and bottom, just the bottom.
I deflect the aileron all the way up, and apply the tape to one side first, with the tape kinda folded. Then, slowly work it onto the other surface. Be sure to push it down into the gap as far as possible so as not to create binding in the aileron.
You can also use Monokote, just iron it on one side first, then the other, just like if it was tape.

So correct me if I'm wrong, if I was doing the elevator...I would deflect the elevator up (up elevator) and apply the tape or monocote on the bottom making sure to get it in the gap as far as possible?? Just want to make sure I get this right. Won't be able to get it into the gap too far since the control surfaces have those CA hinges.

Yep, you've got it right. Make sure to do the ailerons too.

If your control surface is deflected more than enough, you don't have to push the tape/monokote into the gap any more (poor grammar?). I deflect the surface, lay the tape on (or monokote), and then relax the deflection and make sure the tape folds into the gap, not out. Then I'm done.

Kurt

Guys
Do you seal all gaps? I just finished building a Cermark 25% Extra 260. I hinged with countersunk pivot point hinges, so the gap is almost negligible, but I sealed the ailerons with clear monokote on the bottom anyway. I did not do the elevator because it was so tight. Seems to me that if I were to do the rudder, it would be best to seal both sides.

Any thoughts?

Even the full size gliders only seal one side of the rudder. All you are trying to do is to prevent the leakage of air from the higher pressure side to the lower pressure side. If what you are thinking was correct, then you would have to do it both sides of aileron and elevator too.
Evan, WB #12.

One side is all you need as pimmnz said, just to stop crossflow.

...oh you guys should also say "be carefull the next flight" because they can increase effectiveness of the control surfaces either not much or a whole bunch....so be ready for it to be faster.

Steve

All great information everyone. I picked up my blenderm tape so I'm ready to seal! Thanks for the replies...super helpful. Doug

Any time Mav, let us know how it flies afterwards.