How much does sealing hing gaps help for a sports plane, like a revolver 70? or any rc plane? what is the best way to seal the gap?</p>

sealing both sides insures equal response
other than that - just keep em close to touching but do insure they are equal
sometimes they reduceflutte - because they act as a damper to movement.

Sealing one side of the gap works fine.

I have used hinge gap tape on a glow plane - really dumb idea. Adhesive not up to dealing with glow exhaust spooge.

I prefer using film - Ultracote 'cause that's all I use to cover my planes. If the fixed surface and the associated movable control surface are of the same color with no trim pieces crossing the hinge line then use the same colored film. If they are different colors or there's trim pieces crossing the hinge line use "clear" film. Ultracote has a light weight clear.

How? Cut a strip 1/2" wide just about as long as the hinge gap. Crease the strip in half and lay the "V" into the hinge gap. Seal one side or the other first - your choice. Then move the control surface to its extreme high-rate position. While holding it in the extreme position seal the other half of the strip. This will ensure that you have full control surface movement. If using Robart hinge points then it might work better to cut smaller pieces for the gaps between the hinges. Depends on how big the hinge bulge is. CA hinges - not necessary at all. Dubro nylon pinned hinges - maybe - depends on the build job.

If your exhaust is out the bottom then seal the bottom gaps. I'd seal the left side of the rudder.

If you're pretty anal about the look of the plane you can seal both sides as suggested earlier.

Thanks for the info, I'll see if I can find some clear covering and seal them this week, does it mater if I use monocote over ultracote or visa versa? I ahve also heard of peopel using clear packing tape, does that work ok too?

It's all about how the adhesive reacts to glow fuel residue. Try a test strip - wet it with fuel - see what happens.

Sure, you can mix and match between Ultra &amp; Mono. If the plane has been flown just make sure that the surface is as squeaky clean as possible.

Sealing both sides - I meant to say sealing both wing panels -
how it's done - a matter of choice.
3M ,makes a clear vinyl tape -which is excellent - there are likely other good vinyl tapes .
Vibration can kill some of the packing tapes. they are not vinyl.
The plastic used for signs is usually good and some places will give you scraps which match

It always help for any control surface, as long as it does not interfere with the full deflection of the control surfaces.

At high AOA, there is a difference of pressures between both sides.
Any open gap allows a flow of air from the high pressure side to the low pressure side.
The main flow of air on the low pressure side is disturbed by this stream of leaking air that is flowing in a direction that is perpendicular to it.
That disturbance creates or increase turbulence that reduces the control action of the low pressure side of the control surface.

At low AOA's the problem is not that relevant.

I have used the 3m transparent vinyl tape mentioned by rmh, which has shown resistance to glow fuel of months.

Providing the surfaces are well fitted and gaps are quite tight then i honestly dont think you will notice any difference at allfrom sealing the gaps. Certainly there is no point sealing both sides, sealing from one side only stops air 'leaking' in either direction anyway.

PS.. the difference in pressure between one side of the wing and the other is the same regardless of AoA (assuming the plane is in level flight in both cases).

My old dogeared copy of Abbot and Doenhoff has data showing efficiency gains in the 15-20% range in its chapter on lift enhancing devices (like flaps)

On models the picture changes and efficiencies are much harder to predict.

What about the style of hinge that is on a molded wing where one side of the hinge is made by a kevlar strip and the other side is open. On the flap where it is hinged on the bottom and when the flap is deployed there is a large open surface on the top, and on the aileron it is hinged on the top and ther is a large on the bottom. There really isn't a way to seal the open side.

those are very good setups - also no need to seal top of those flap setups

Thin clear mylar that I got from Model Research Labs is excellent for this task. Requires low heat, lower than MK or UK so you are never in danger of screwing up the finish, especially if its paint. After creasing lengthwise, I use a thin strip of metal straightedge inserted in the hinge line to hold it while heating it in place.

I don't like using adhesive backed clear tape to seal hinge lines. These will tend to stick and often fail prematurely. I have done it tho....I also sprinkled baby powder in the hinge line to keep stickiness down

At these low RE's, it is doubtful to affect cd. At higher AoA it might be possible to delay onset of flow separation. I know the full scale cessna's and pipers use gap seals to increase controlability at lower speeds.

I sealed the gaps on my Avistar after I flattened the wing and added flaps and separate ailerons.

Loops are now straight as an arrow and it does not fall off to one side anymore.

Landings are extremely slow and with all the gaps filled it just mushes down and never drops a wing. I did laterally balance it also though.

Uhaaaa?? (trying to sound like a dawg) - Ain't that standard operating procedure for every plane?

No, I dont think it is.
I'm sure we're gonna get OT but it would be a interesting discussion with all the ARF's and El Chepo .com planes now days.
I would wager most are NOT laterally balanced.

I sealed the gaps on my Ultra Stick and it felt like the control response became more consistent. Of course, that could have just been me looking for a benefit since I was expecting something.

A handy product for it is 3M Blenderm tape. It's a clear medical tape that is practically invisible when it's on, and it's made to stick to oily skin so glow residue doesn't affect it.

Here is another one I will have a little fun with and probably get flamed, but here we go. I have been building and flying for over 35 years, control line, sail planes, 1/2 A thru gas rc (sport, scale and a few racers) and I have NEVER sealed a hinge line. I have only had a few incidends of flutter and that was due to either too large of a gap in the hinge line (building issue) and exceeding the airplane design speed. The throttle is used for that. Not to say it may not increase some efficiencies, but on a sport plane as the post started, would anyone really notice???????

John

I had a Sig Zlin that had "sealed" gaps designed into the airframe. While not technically "sealed", any airflow was redirected across the surface. Something like the attached drawing.

I only sealed the hinge gap in my EF 50cc Extra, but the rest of my planes are not sealed, but the gaps are pristine and extremely close. I like them that way. I do have a question that falls into this catagory. How much of a hinge gap is too large of a gap to seal, or will there be problems sealing such a gap?

I recently purchased an Edge 540 26-30cc 73" wing plane that has the worse hinge job on the ailerons I have ever seen and the worse than any of my planes. I think the chinaman had too much Saki when he hinged this one. I have never worked with a gap this bad and so thought I would inquire from you wiser ones on this.

The stabs and rudder are ok and will work with sealing the gaps. I do have to replace one hinge on the rudder, but no big deal there. The hinges in the ailerons are Robart style hinges and would require removing them all and sealing up the holes, re-drilling and replacing the hinges which is way more labor than I desire (or have the time) to put into a NEW ARF.

So, how much on ailerons is too much of a gap to seal? I was wondering if I can slip by with this plane by taking a chance on sealing the gaps with covering or Blenderm tape on both sides and see what happens. If re-hinging is the right thing to do then I will do that but maybe later on as I want to put another 30cc in my fleet.

Hoping for some replies from those of you that have ran into this problem before.

Fly it and see how it performs, it may work just fine as is. A large hinge gap usually just desensitizes the aileron control.

If its sealed then no air will spill through. With that much of a span I think Blenderm would be best.