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Old September 29th 03, 03:40 PM
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Default Props and Wing Warping... was soaring vs. flaping

Not wanting to post at the end of a mile-long thread, I'm starting a new one
(so sue me.) Here are a few clarifications regarding the Wrights, wing
warping, and ancient props, from a guy currently nursing a deep thigh bruise
inflicted by the hip cradle of a Wright 1902 glider.

Props first: Nope my ship doesn't have props... they were invented the year
after. But, The Wright Experience website mentioned that the 1903 prop
replicas actually tested out at about 83% vs. 86% for modern wood props. An
interesting factoid.

Now wing warping: In the 1899, 1900, 1901, and the early config. of the 1902
Wright machines, the wings all warp the same way. The ends of the biplane wing
truss are twisted by forcing the outer set of struts into parallelagrams.
There are two sets of warping wires. One runs from left upper trailing edge,
through a pulley on the left lower leading edge, incoroprates the hip cradle,
runs through a pulley on the right lower leading edge, and ends that the right
upper trailing edge. The second wire runs from the left upper leading edge,
through a pulley at the left lower rear spar, makes a straight shot across the
lower wing, through another pulley on the right lower rear spar, and ends at
the right upper leading edge.

The wing is effectively warped when the hip cradle pulls the first wire. On
one side of the aircraft, the distance between the upper rear spar and lower
leading edge is decreased, while on the other side of the aircraft, the
opposite happens. In the side that is decreased, the distance between the
upper leading edge and the lower rear spar is increased. This in effect pulls
the second wire forcing the other wingtip into an oposite facing parallelagram.
The upper and lower wingtips move fore and aft of each other in the process.
Since the 4 center struts of the aircraft are wire braced fore and aft, they
remain square. The end result is that the wings twist, with one wingtip
pitched up, while the other is pitched down. This increases lift on one
wingtip, while reducing it on the other. It also increases drag on one side
while reducing it on the other, hence the movable rudder innovation and 3-axis

All of this is fine and dandy EXCEPT, that on the 1903 flyer, and all
successive Wright machines, the wings DO NOT warp this way. Look carefully at
the photos and you'll see that the wing warping wires are now ALL on the rear
spar. One set of pulleys has been relocated from the leading edges of the
lower wing to the rear spar of the UPPER wing. Not only that, they have been
moved inboard, near the mid-plane set of struts. WHY? Two reasons. First, a
larger center section of the 1903 machine had to be rigidly trussed fore and
aft to accomodate an engine, PSRU, and props. To do this, the Wrights built
each wing in three sections instead of one, and joined the wing sections with
hinged joints at the spars. Second, they had discovered in 1902 that by
changing the configuration of the bracing wires, they could force the leading
edges of the wingtips to remain stationary. Only the trailing edges of the
wingtips would would move when warped, making them act much more like modern
alerions (sp?). This would explain why the trailing edges of the wingtips on
the 1903 travel nearly a foot or more vertically from lock to lock, while the
early 1902 only manages about 3 inches.

The 1902 glider was flown with this altered bracing setup in the latter part of
the 1902 season, and again in 1903. All of the long flights, including both
the time and distance records were made using this setup. However, the methods
used to achieve this setup are not contained in the Wrights notes from 1902.
It was not yet in use when the 1902 photos were taken, and is not visable in
the 1903 photos of this glider. However, I did find documentable proof that
this setup was used in 1902. I'm planning to test this setup in a few days and
may display it at Wings Over Houston if I can get it working in time.

The Wrights attempted to patent the entire flying machine, believing that if
they had done the scientific work necessary to invent modern aerodynamics and
propeller theory, they should be to ones to benefit financially. In the end,
only the wing warping idea was patented. Alerions (sp?) were definately an end
run around the patent. Wilbur believed (correctly) that they were less
efficient and never used them. However, they ultimately possessed one
charecteristic that wing warping did not: they could be scaled up. And the
bigger airplanes got, the more they became necessary. Say what you will about
the correctness of the Wrights' legal actions. I doubt any of us in a similar
situation would have done differently. What happened is the way things were
meant to go. That's all there is to it.

Every time I look at thier work, I find another secret that Wilbur and Orville
cleaverly hid. It makes me wonder what else I'm still missing.

Fun stuff,
Google search: Wright Brothers Enterprises