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Polishing the glider's paint - a brief experiment with an electric dual-action polisher on a test piece.

I used a coarse foam disk and cutting/buffing (not polishing) compound. The machine was at the lowest speed and light pressure was used for a minute or two.

This is a promising follow up to: universeodon.com/@KrajciTom/11

The difference in surface prep was obvious. Where the paint had been sanded with 1200, the surface gained a gloss almost instantly. If the surface was sanded with 600, it remained hazy. Those sections only sanded with 400 were very hazy, even with more polishing time and a bit more pressure.

It looks like I'll hand sand to 1200, then use the electric polisher.

I just had an idea. If I build a bracket/clamp to hold the polisher upside down, I can hold small parts and better control the process.


@KrajciTom

Ah sanding off all the rough surface boundary layer adhesion magic.

@darryl_ramm

What do we know about surface quality/finish and its impact on drag? Do such studies date back to Ye Olde NACA?

@KrajciTom

Ya just got to put the rough bits where it matters and hope it does less harm that good. I think you need to conduct those experiments. Polish it all up shiny, do some Dick Johnson style L/D and oil stain measurements and then maybe dimple the wing with a punch and hammer to resemble a golf ball. Start at the trailing edge and work forwards measuring as you go. 🙂

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Thought I noticed somewhere Schleicher giving up on blown flaperon turbolators. Maybe just on one model glider? Not sure, can't find it now. Ah marketing vs. aerodynamics vs. practical issues.

TomKrajci 🇺🇦 🏳️‍🌈 🏳️‍⚧️

@darryl_ramm

I think the info about abandoning turbulators was in a Stefan Langer video where he's touring the HpH factory.

@KrajciTom

No, this one was something from Schleicher maybe a TN or new glider brochure.