In message <v01530501ad249ec2bd81@[193.122.159.50]>, Ian Seager
<ians@avnet.co.uk> writes
>I have seen some (laminar flow) gliders with turb tape on the underside of
>the wings, the pilots said that it was to increase performance (OK so they
>wouldn't put it there to decrease it I know). But they didn't know why it
>should work...can anyone offer a simple explanation?
I would guess that it was there to effect re-attachment during the
penetration phase of gliding ie. at low AOA rather than for the soaring
phase. Transition on the bottom side generally occurs a little way aft
of the top side making the critical Reynolds number higher. Maybe
someone found that by introducing some form of boundary layer control
the mainstream flow could be increased slightly before reaching the
critical Re thus improving the penetration speed. Don't forget that high
aspect ratio glider wings operate with much lower Reynold numbers than
most powered planes and can often be operating around critical values of
Re.
--
Graham E Laucht
|