Gap seals

[cubdriver2]

Looking for thread we had a couple weeks ago on gap seal tape

Glenn

[cubdriver2]

Sooo I put it on top, 2" with a 3/4" opposite middle bottom tape



Glenn

[skywagon8a]

Like this. When the surface moves it will remain the same tautness. The way you show it, it will be tight when the surface moves one direction and loose when it moves the other direction. There was a bulletin to do this on the Bellanca years ago.

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[courierguy]

I found some neutral colored foam weather stripping that perfectly seals the gap between my horizontal stab and my elevator on the RANS, and gained 3 MPH top speed and knocked off 2 MPH off the stall! No, not really, but it makes me feel better knowing it's back there and it doesn't add any weight, and I had it leftover from sealing up my doors.

[skywagon8a]

I found some neutral colored foam weather stripping that perfectly seals the gap between my horizontal stab and my elevator on the RANS, and gained 3 MPH top speed and knocked off 2 MPH off the stall! No, not really, but it makes me feel better knowing it's back there and it doesn't add any weight, and I had it leftover from sealing up my doors.

Was there any speed change? With a fixed stabilizer and a trim tab on the elevator, the two surfaces are not always perfectly aligned. Therefore there could be some tendency for air flow along the hinge line creating a minimal amount of drag. Don't know if it is measurable, particularly on slow airplanes.

[cubdrvr]

Blenderm .... position elevator to its lowest point and just tape on top the length of the gap.Cut out for hinges

[courierguy]

Was there any speed change? With a fixed stabilizer and a trim tab on the elevator, the two surfaces are not always perfectly aligned. Therefore there could be some tendency for air flow along the hinge line creating a minimal amount of drag. Don't know if it is measurable, particularly on slow airplanes.

My thinking also, it HAS to help. Can't hurt anyway....and other than any "speed increase" (I spend a lot of my time in the 70's, because I like it there) and drag reduction will help climb, range/duration, glide etc. Unless there is a major drawback (like ditching the 29" Airstreaks for 6:00's would be) I'll clean things up when possible.

[dgapilot]

On gliders we use Mylar tape for gap seals, wide enough to cover the gap, double sided tape on the fixed surface to adhere the Mylar. If you are worried about scuffing the movable surface, put Teflon tape on that.


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[skywagon8a]

This is another method. Balsa wood faired and glued to the surface leading edge, covered with a fabric tape. Does it work? Don't know, as it was installed before the first flight. It does close the gap.

[Kodiakmack]

Any link for a kit for pa-12 with -18 feathers?

[Scooter7779h]

Any link for a kit for pa-12 with -18 feathers?

I got mine field approved. 11 pieces of paper but walked into FSDO dropped off the application, had a cup of coffee and picked up signed 337. You need to buy the PA-18 STC and have previously approved PA-18 tail feathers to go the way I did.


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[cubdriver2]

Like this. When the surface moves it will remain the same tautness. The way you show it, it will be tight when the surface moves one direction and loose when it moves the other direction. There was a bulletin to do this on the Bellanca years ago.

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I don't think I like it?

Glenn

[skywagon8a]

I don't think I like it?

Glenn

Just curious, what don't you like about it?

[Farmboy]

Like this. When the surface moves it will remain the same tautness. The way you show it, it will be tight when the surface moves one direction and loose when it moves the other direction. There was a bulletin to do this on the Bellanca years ago.

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Maule Aircraft does it this way at the factory .


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[BC12D-4-85]

Not to discourage but tape and fabric can become a trap for snow and ice. Clean it out before flight. Spruce sells a foam seal for Pitts I stuck in my Taylorcraft gaps. Floats in place ok not glued.

Gary

[cubdriver2]

Maule Aircraft does it this way at the factory .


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Stick was heavier at same speed

Glenn

[Utah-Jay]

My buddies CC has a foam gap seal between his H-stab and elevator

[skywagon8a]

Stick was heavier at same speed

Glenn

That means it works.

[cubdriver2]

That means it works.

I knew you were going to say that

Glenn

[BC12D-4-85]

My goal for the Taylorcraft's seals was to improve elevator trim effectiveness. 1941's had a small elevator tab, later after WWII they enlarged it - like double in length. Now at constant power I can fly via trim full nose up about 5 mph slower - 55 vs 60 IAS. More nose up authority from the seals I guess.

Gary

[salex]

What do we know about this stuff?
https://store.cubcrafters.com/Foam-G...18_p_1298.html

[BC12D-4-85]

What's the real question is why the designers of tail surface gaps left them so large? Surely the obvious leakage of air through them didn't escape their observation?

Gary

[skywagon8a]

What's the real question is why the designers of tail surface gaps left them so large? Surely the obvious leakage of air through them didn't escape their observation?

Gary

The real answer is Who cares? The airplane has adequate control function in order to pass all the required FAA (or in the case of these planes CAA) tests. The desire to close the gaps is only a personal pilot owner thing. Sure they do something, but they aren't necessary to satisfy the FAA. Perhaps their installation is only to cover up some poor piloting techniques?

[frequent_flyer]

What do we know about this stuff?
https://store.cubcrafters.com/Foam-G...18_p_1298.html

It is used on the FX-3 elevator and rudder. I've had mine for about 2 years and about 200 hours of flying. They are easy to fit and remove but they don't fall out. No sign of deterioration in 2 years but the aircraft is hangared. I was concerned that dust and dirt would get trapped in then and abrade the paint but no problem so far.

[BC12D-4-85]

The real answer is Who cares? The airplane has adequate control function in order to pass all the required FAA (or in the case of these planes CAA) tests. The desire to close the gaps is only a personal pilot owner thing. Sure they do something, but they aren't necessary to satisfy the FAA. Perhaps their installation is only to cover up some poor piloting techniques?

Bellanca cared enough to close the gaps on their 7GCBC and 8KCAB. Likely others that are promoted for aerobatics but I've not checked. Brisk empennage control authority is desirable by some while exercising proper piloting technique. Then there's the aileron gap seals that promote STOL and roll rate on Cessna's and again Bellancas.

Gary

[skywagon8a]

This is the question I was answering.

What's the real question is why the designers of tail surface gaps left them so large?

Gary

Bellanca cared enough to close the gaps on their 7GCBC and 8KCAB. Likely others that are promoted for aerobatics but I've not checked. Brisk empennage control authority is desirable by some while exercising proper piloting technique. Then there's the aileron gap seals that promote STOL and roll rate on Cessna's and again Bellancas.

Gary

A manufacturer can chose for whatever reason to close or leave open the gaps. The only question they need to answer is "Will it pass the FAA flight tests?" There could be any number of reasons to close or leave open the gaps. Some reasons you may not even think of.