Propellors vs Rotors

Hi Harry,

wright1902glider wrote:
GET BACK IN THERE! 'YA DAMN WORMS!

;-)

The original Wright 16" wind tunnel did not survive history. However,
the original balances and test airfoils did and are currently at the
Franklin Institute in Philly. Orville stored them in a box for years
and almost threw them out once. Thanks for shaking that box Orv. There
are numerous reproduction wind tunnels in museums. I'm planning to
build one myself. Nick Engler had blueprints for one on his website
http://first-to-fly.com/Adventure/Wo..._and_drift.htm

Harry "rotor-ramp-rat" Frey

I misunderstood what I was seeing at the Air Force museum. You
are correct that it is a 3/4 scale replica constructed under Orville
Wright's guidance sometime before WWII.

http://www.centennialofflight.gov/wb...ind-tunnel.pdf

This link also refers to the balances and experiments you are talking
about.

Thanks for correcting me.

BTW, I think that the discussion about the way wings work
is fascinating although slightly off the original topic.

IIRC the diplacement of the air molecules around a wing can be
conclusively demonstrated by multiple smoke streams in a wind
tunnel, or by mutiple dye streams in a water tank. I remember
such demonstrations in the lab back at good ole Wichita State
U.

I've only got one such photo available right now, and it is on page
141 of "Fluid Mechanics" 5th edition by Ray Binder. It shows a
symmetric airfoil at approximately 20 degrees AOA. In the photo
_all_ of the smoke streams (e.g. both the ones above the airfoil
and the ones below) that are disturbed by the airfoil end up
lower than they started out. This shows that a symmetric
airfoil at positive AOA pushes the air below it down, and _also_
pulls the air above it down. The net result is a slight downward
displacement of a _lot_ of air including air that is ~2x the chord
away from the airfoil.

I'll try to see if I can find similar photos on the web because I
think it will enliven this discussion to the general benefit of all
the participants (including me).

Don W.