>I vaguely recollect the factory tested a classic with this mod years ago.
>It turned out the airflow was much worse than with no root extensions.
>Worth asking them about it.
>Pete
This was back in the Pete Clarke days.Ivan took the liberty of tufting my
Classic (he did ask) which had extended root fairings extended on the
bottom of the flap to cover cross tube slot. His interest was the cooling
air outlets above the cowling split at the back and we were both surprised
that it didn't upset the airflow over the fuselage. He claimed that the
root fairings "trashed" the airflow at the back of the wing. Not true,
there was one tuft shaking a bit just above the flap in the clean
condition. My guess is that lifting the trailing edge of the flap fairing a
bit would cure it. Flaps down there was separation as you would expect. He
also claimed that without fillet extensions over the flap the flow was
better but he never would show me any photos to prove it! I did see my own
tufts in action (Pete flew G-KWIP) and took a couple of pictures. I will
try and find them. KWIP had a few other mods so its not comparable to other
Classics, best full power speed I ever saw was 137 Kts with 912 & PV50
prop. That was with the cooling outlets at the rear of the top cowl. I
changed it after that and never saw the same speed again. Fool!
My EZ friends have done a lot of this sort of thing. They usually paint the
area of interest with old engine oil, (there is a better way, oil + a dye
but I have no details) then go fly at the relevant airspeed, then either
photograph air to air or land and photograph. Rutan did a lot of this in
the early days too.
We owe a lot to Burt Rutan. I do hope his homebuilt spaceship works.
Graham
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