Eric,

 If I understand your comments in this thread, you have the capability to
 test props and prop configurations.  Have you researched the Kline
Fogleman
 air foil?  http://www.rexresearch.com/klinfogl/klinfogl.htm  It would be
 interesting for someone with testing capability to apply this to a ducted
 fan configuration.  The airfoil configuration could be applied to both the
 prop and the fairing.

 However, if one was able to eek out an additional 10% efficiency out of
the
 prop and another 10% out of the fairing, that still would give you a
Lambda
 i of only 7.2.  Is that enough to get you where you need to be?  If so, it
 might be worth experimenting.

 Gordon

 It has been around since 1984. How come I don't see it on any airplanes?

 Paul Lamar



Hmm.  No mention of Reynolds number, even though the data was taken on
scale models.  Where's the L/D, and lift coefficient and alpha plots?
A bit short "real" aerodynamic discussion..


Matt-


Matt,

It was a short discussion with no data.  I have looked for hard data and
only find qualitative evaluations for the wing configurations and absolutely
nothing on the propeller notches.  Which is precisely the reason for the
question as to whether Eric has the capability to test, and of course it is
entirely up to him if he has any inclination to pursue it.

I did find an interesting comment relative to the airfoil in wings and it
may answer Paul's question as to why it has not been utilized in aircraft.

LBMiller5 <http://www.rcgroups.com/forums/member.php?u=52070

<http://www.rcgroups.com/pages/advertising/

<http://www.rcgroups.com/forums/member.php?u=52070

I have studied aerodynamics for many years, and I have designed several
dozen RC aircraft. The Kline-Fogelman airfoil does work for RC aircraft and
for small ultra-light type aircraft. The reason that the airfoil never
caught on in general aviation is that it has a very high induced drag at
higher airspeeds. At the low airspeeds and low Reynolds numbers that we fly
our models at, induced drag is not much of a problem, and ultralights, that
have a regulated fixed maximum speed of 63 MPH don't go fast enough to see
much induced drag.

A lot of wind tunnel testing was done on this wing, and on a plane the size
of a Cessna 172 or Piper Cherokee, the induced drag at cruising speeds
around 120-150 MPH was much higher than a conventional airfoil. Since most
general aviation aircraft spend the majority of there time flying at 65-75%
cruise power, that is where the designers try to optimize the performance.
The small gains in low speed stability do not make up for the large drag
losses at cruise speed, so the end result was that the airfoil was not
suitable for general aviation use.

Lucien

Gordon