Rock Rolling & Other Easter Chores

On Apr 14, 6:12*am, Brian Whatcott wrote:
Oliver Arend wrote:
I don't know about Wright flyers or gliders, but "normal" airplanes
(according to my limited experience on Robins and Cessnas) will
actually turn the proper way...
Oliver

The effect in discussion is called adverse yaw. * It takes design effort
to get rid of it. * The most popular method is called differential
aileron movement: i.e. more UP than down. If I recall, that's the method
used on those two popular planes. * But the early planes had a more
serious problem too. * *When they flew just above stall as they did, the
wings were already at high angle of attack. * *If you then deflect the
outboard section down, it stalls. *Vividly sometimes. Modern practice is
to use a little washout - i.e. lower AofA towards the tips - that makes
the stall progressive.

Brian W



BUT ! ! ! Wright machines AREN'T "normal airplanes". Are they?

BUT ! ! ! Wright machines NEVER had ailerons. NEVER. NONE of them. Not
even one.

BUT ! ! ! Wright machines didn't and COULD NOT fly at an Angle of
Incidence (AOA for you new guys) over 11 degrees.

BUT ! ! ! Wright machines DID have washed-out wings starting in 1902.

So what gives, Harry?

First, semi-pilot refers to the fact that I was trying to keep my
glider on the ground instead of in the air. Why would I do a damn-fool
thing like that? Becuz I was at an airshow and I didn't want my baby
soaring up and into a WC-130. Still had to fly it for nearly three
hours to keep it from rolling or getting airborne. Shoulda seen the
size of the thigh bruises I had from the hip-cradle. (They didn't tell
you about that in the book? Opps.) So when I speak about this subject,
it is with "some" experience.

Adverse yaw IS the modern term for the "well-digging" effect. What
really happens when you warp the wings of a 1900 or 1901 Wright glider
left-leading-edge-down? You roll sllllllooooooowwwwwwwly to the left,
and yaw rapidly to the right. Why, well it is differential drag caused
by differential AOA. Higher drag in the UP-warped wingtip. IT IS NOT
because of a high overall AOA or lack of washout. Its because one
primary factor. The 1900, 1901, and early 1902 gliders DIDN'T HAVE A
CONTROLLABLE RUDDER! THAT'S IT. END OF STORY. On October 19, 1902,
Orville litterally had a dream about the third axis of control. Wilbur
suggested the idea of integrating rudder and aileron control the next
morning. They tried that setup on October 23, 1902 and DAMNED IF HE
AIN'T FLEW!

Flex-wing hang-glider, blah blah B-2, blah blah PPC, etc. Yeah, I
know. We're talking about Wright machines here. So, by 1902 we had
washout, tapered wingtips, and three-axis controls. What about 1903?
Now we've got a little power, refined actuation, and more control
surface area, and one more thing: a pitch stick. Its mounted to the
elevator control-bar, but it IS the beginnings of a joystick. Same
setup in 1904.

Now late in 1905, there is another significant change. A seat. (Look
Ullm, no more criked necks!) Of course, if you're sitting up, you
can't really use a hip-cradle. So now what? Another stick! So now
there's one for pitch, and a second for wing-warping and rudder.

BUT WAIT, THERE'S MORE! In very late 1905, the rudder was uncoupled
from the warp-wires so it could be controlled on its own. Because
sometimes you need more rudder and sometimes you don't. So how to
control it? You add a hinge 3/5 of the way up your warping stick. You
still push/pull fore/aft for warping, but now you BEND left/right for
rudder on the same stick. The easiest place to see this setup is on
the 1908 - Model C machines. And what do you do with your feet? Dangle
them. Put 'em on the foot rest. Chairdance.

So now we have independent three-axis control via 2 1/2 sticks. Is
adverse yaw and spinning still a problem? You bet. That's how Ralph
Johnstone bought it. BUT..... the development of this system, and
equally importantly AROUND THE PATIENT of this system gave us what we
have today.

So to answer the question directly, what happens in a Wright when you
warp left leading-edge down?

1900 - early 1902: You roll left but spin right and/or stall, crash,
or fly backwards.
late 1902 - early 1904: You roll and turn left if you have enough
airspeed, otherwise you stall and crash.
1905-1918: Pilot's choice. Depends on rudder input and airspeed.
Modern airplanes: Depends a lot on design, but you can still spin and/
or stall if you get stupid.
Flex-wings: they don't warp. They don't have ailerons. Way different
mojo.
Stealth Bomber: Computers my friend. The only one that has crashed
went down on takeoff due to a damp 'puter.

BTW Bob, if you're still with me after this rant, I did happen to see
a joystick in a reproduction Spad once that looked an AWEFUL lot like
a sawed-up wooden baseball bat. Food for thought.

Harry