On Nov 7, 11:36*pm, "noel.wade" wrote:
Couldn't the wing use multiple airfoils or varying thicknesses to get
around the need for (as much) washout, despite the moderate taper
ratio? *Those wouldn't be immediately obvious from the visuals or 3-
views... **shrug*

--Noel

Multiple airfoils is a slick way to design the desired tip stalling
characteristics into a plane. I'm not sure if the Perkoz uses this,
but I have noticed it seems to have a good bit of forward sweep to the
wing. Forward sweep can certainly be used instead of washout, as
demonstrated clearly on the Sisu.

Based on independent tests I've seen done on other Polish gliders, I
have no reason to doubt the SZD figures for the 54. The Pols have
always been rather scientific and less optimistic about their polars
and such.

-Paul Hanson
SZD-59 driver, claimed at 40/1 by SZD (wet w/winglets...) and measured
by Johnson at 38/1 (dry w/no winglets...)