"James Linn" wrote in message
...

"sddso" wrote in message
...
Closeup examination of the Dr.1 at Old Rhinebeck Aerodrome indicates
that its main airfoils had far less wire bracing than any Sopwith design
(can't recall if Rhinebeck has a Camel or not at the moment). Were the
differences in parasitic drag enough to cause difference in max
attainable speed?

Memory suggests that Rhinebeck's airframes are as faithful to original
as can be found anywhere.


As discussed in the program, the wires did make the Sopwith more
vulnerable
to enemy fire.

But the limiting factor in the design was the drag of three wings. Sopwith
had realised this and not gone into big production with their triplane.


With the Dr-1 the wing structure was completely internal (it was a
cantilever design) which removed the conventional wire bracing and the
associated high drag. For this reason the Dr-1 had one of the best zero-lift
drag co-efficients of the war.



What's most important is the first use of thick aerofoil sections, based on
the work of Prandtl's Gotteingen laboratory in '17. These were proved
superior over the thin aerofoils used by the Allies, who were plagued with
the associated poor high-lift characteristics of slender aerofoils. The
Dr-1's thick aerofoil gave the lil' Fokker a tremendously high rate of climb
and enhanced manoeuvrability; Sopwith were just simply barking up the wrong
tree.



Anyway, Sopwith's preference for thin aerofoils is based on birds having
similarly slender wing cross-sections, so they weren't even barking.



The D-VII's excellent performance (also due to its high t/c) made it so
respected by the allies that it was the only aircraft to be specifically
listed in the armistice (article IV). Just goes to show how much a couple of
inches on the thickness of a main spar can go a long way!





Jim Doyle