Control surface gap seals?

[13brv3]

Greetings,

There has been some talk of using gap seals for various control surfaces, and in particular I'd be interested in trying to improve the yaw stability of a Onex. I've seen comments about this in an old thread, but also inside a more recent thread on other subjet. I thought I'd start a new one to make this more easily searchable.

The old thread talked of using thin aluminum for the seal- viewtopic.php?f=5&t=4959&hilit=gap+seal

It's been suggested to use mylar gap seals from these guys:
https://wingsandwheels.com/tapes-seals.html
https://wingsandwheels.com/tapes-seals/ ... -seal.html

Has anyone actually done this with mylar or similar tape? The non-flush rivets at the trailing edge would make this difficult. The pre-curved tape available at wings and wheels isn't wide enough, and I'm not sure the flat tape could be creased to work. I'm sure other places sell similar material. Just curious if anyone has actually done it. Bonus points for picture of how you did it :-)

[BRS]

Considering the large sonex control surface gaps, one would think there'd be a benefit to sealing them up.
I wonder if anyone from the factory has comments on this. No doubt it has been tried. I've been using Wings&Wheels tape on my planes for many years. Mostly where fairings meet wing struts (sportsman).

[daleandee]

Considering the large sonex control surface gaps, one would think there'd be a benefit to sealing them up.
I wonder if anyone from the factory has comments on this. No doubt it has been tried.

Many years ago John Davis (RIP) of American Sonex Association fame sealed the gaps on his Sonex tailwheel plane (Jabiru 3300). His testing found absolutely no advantage to sealing those areas. Others have tried vortex generators (VGs) and found little to no advantage. The design of the Sonex is very good and it seems there is not much to be done to enhance it.

Some have added wingtip extensions and claimed positive effects. I have no idea what results they did or didn't get with those.

Dale
3.0 Corvair/Tailwheel

[13brv3]

Most of what you read about gap seals refers to closing the airflow path from one side of the surface to the other. Usually, it's referring to a lifting surface where there's high pressure on the bottom and lower pressure on top.

With the full length hinges that Sonex uses, there would be very little airflow past them, so from that standpoint the gap is already sealed. On the other hand, the hinge vs gap sides are very different, and I'd figure there's some airflow differences caused by the gap. It would be interesting to see some wind tunnel testing of the control surfaces.

[Skippydiesel]

I think 13brv3 is making the most sense here.

Gap seals are generally to reduce/prevent the air flow from high pressure (under side) to low pressure (upper side). The piano hinges on Sonex aircraft flaps/ailerons/elevators, achieve this pretty well.

You could reduce the gap between aileron & flap.Great care would need to be taken to prevent any chance of interfering with aileron movement.

As I understand it the main benefit, if any, would be in slow flight.