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Old Jan 25, 2013, 01:55 PM
"...certainty is absurd."
kcaldwel's Avatar
Joined Jan 2007
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Albert Einstein designed an airfoil!

It was based on Bernoulli's principle only, without understanding circulation. It was a very poor airfoil! It was called the "cat's back airfoil", and the theory was it would work like a venturi, and generate lift at zero angle of attack, without the other side or a plate down the axis of symmetry. The top was intended to generate suction, the bottom to generate pressure, all with low drag.

It was tested at Gottingen, and even flown. The flying characteristics were described as being like "a pregnant duck".

There are a few pages about it in this book, starting on Pg. 3 I think:

http://books.google.ca/books?id=EoMi...nstein+airfoil

The coordinates were lost during bombing in WW2.

There is a good description in the "Enigma of the Airfoil", by David Bloor, which I got for Christmas. I've really enjoyed reading the book which goes through the entire history of the development of wing and and airfoil theory in Britian and Germany from the 1800's to 1930.

Kevin
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Last edited by kcaldwel; Jan 25, 2013 at 09:48 PM.
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Old Jan 26, 2013, 11:26 AM
internet gadfly
nmasters's Avatar
Colorado
Joined Aug 2006
2,171 Posts
Give a smart guy specious information on a subject outside of his area of expertise and he'll look just as dumb as the rest of us. LOL

Thanks for the Googl books link, Kevin

Quote:
Originally Posted by kcaldwel View Post
It was based on Bernoulli's principle only, without understanding circulation. It was a very poor airfoil! It was called the "cat's back airfoil", and the theory was it would work like a venturi, and generate lift at zero angle of attack, without the other side or a plate down the axis of symmetry. The top was intended to generate suction, the bottom to generate pressure, all with low drag.

It was tested at Gottingen, and even flown. The flying characteristics were described as being like "a pregnant duck".

There are a few pages about it in this book, starting on Pg. 3 I think:

http://books.google.ca/books?id=EoMi...nstein+airfoil

The coordinates were lost during bombing in WW2.

There is a good description in the "Enigma of the Airfoil", by David Bloor, which I got for Christmas. I've really enjoyed reading the book which goes through the entire history of the development of wing and and airfoil theory in Britian and Germany from the 1800's to 1930.

Kevin
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Old Jan 26, 2013, 12:53 PM
"...certainty is absurd."
kcaldwel's Avatar
Joined Jan 2007
3,632 Posts
They tested some wild and wonderful airfoils at Gottingen in the early days. By the time NACA started after WW1, Prandtl and crew had a lot of it figured out.

The interesting thing in the "Enigma of the Airfoil" is the divide between inviscid theory and viscosity, that exists to this day. The British spent 30 years trying to solve the general Stokes equations with viscosity, because circulation cannot be created in an inviscid fluid. The Germans just got results that worked by dividing the flow up into mostly an inviscid flow with circulation, and a tiny boundary layer where viscosity counted and the transition from laminar to turbulent occurred. They didn't worry too much that it was impossible to create circulation in a truly inviscid fluid. The results they got worked for real airfoils and 3D wings.

I'd never thought it through on those lines before.

It is also interesting that an airfoil designed strictly on Bernoulli theory looks nothing like airfoils designed to create circulation.

Kevin
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Old Jan 26, 2013, 01:12 PM
An itch?. Scratch build.
eflightray's Avatar
South Wales U.K.
Joined Mar 2003
13,411 Posts
Look, I tried my hardest not to post it, honest, ....but..........don't forget....

Robert Ironside invented a wheelchair.

It was based on Benny Hill's principle, only without understanding circular wheels. It was a very poor chair! It was called the "bad back chair", and the theory was it would work like a van turning, and generate laughs at zero angle of attack by the bad guys, without the other side or a policeman feign the appearance of sympathy.


I was forced to do it, It's not my fault.

At least I didn't mention the 'the bottom generating pressure with a slow drag.'

I know, I know, Back where I belong.......
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