Gap seals effectiveness study?

On Monday, June 12, 2017 at 1:38:22 AM UTC-4, Bret Hess wrote:
Hi, we see lots of mylar gap seals and read lots of discussion of them. Does anyone know of an engineering study that quantifies their effect on sailplane wings or other wings? Nothing pops up quickly in Google. I'm wondering how much science there is to this practice.

I'm hoping for more than anecdotal comments. Saying that top racers all use them doesn't tell us much because so do almost everyone.

Look up any of Richard Johnson's flight tests before and after seals, especially the LS-4. Or any other modern sailplane. There was as much as a 5 point difference.

Look up any of Richard Johnson's flight tests before and after seals, especially the LS-4. Or any other modern sailplane. There was as much as a 5 point difference.

Thanks. I read the two LS-4 articles, but the "after" wasn't conclusive: Different plane, different probe positions, and Dick doesn't make much of a conclusion on if the performance was better, or just measured to be better.

Is there another one where he does the same plane with the only difference the mylar seals?

A lot depends on the airfoil and condition of surfaces. For a 1-26 that needs paint, not much difference. On a modern airfoil with 90-95% laminar flow, it makes a bigger difference.
Most really need the internal seals, then various amounts of need for external Mylar seals.

Keep in mind, I don't think they EVER hurt performance.

A lot depends on the airfoil and condition of surfaces. For a 1-26 that needs paint, not much difference.

Disagree, a properly sealed 1-26 has almost 5 mph slower stall, and a crisper roll than one that is not sealed.

Kevin
92, formerly 192

I totally understand about sealing a 1-26, I'm co-owner of 002 and have a lot of 1-26 hours (not as many as Ron Schwartz). Wing root seals (internal and external) as well as fabric aileron/rudder/elevator seals are needed. Mylar seals make little to no difference, that was my point.