KF Airfoils

Below is a brief story Dick Kline emailed us in 2009 about the the KF Airfoil and

Condor Airplane:

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Here's the brief story on The Condor.

When I developed my first stepped airfoil, it had the step on the

bottom. I was pleased with the way it flew, but like so many of us, I

wanted to experiment some more once I nailed down the step on the

bottom. When I placed it on the top I found out that it produced higher

lift than the one on the bottom. It would climb higher and travel a

longer distance. Later tests at Notre Dame confirmed that the step on

the top was able to generate higher lift over drag. I then played

around with placing the elevators on the upper surface just in front of

the rudder. After many different experiments and many different flights

I had perfected The Condor, which would be the plane I would use to

challenge the Wright Brothers distance record. In spite of very strong

winds coming in off Cape Hatteras, I was successfully able to

outdistance the distance record for the first manned flight of 122

feet. I did this in 1985 down in Kill Devil Hills, NC right on the spot

where the Wright Brothers first flew. My distance was 401 feet, four

inches. On the fourth flight that day of the Wright Brothers historic

flight they traveled quite a bit further, so I was lucky that their

first flight was just 122 feet.

Here is the data from the wind tunnel at Notre Dame. It would have been

a lot higher if we had a rounded leading edge and a little camber. But

we were interested in seeing exactly what the step produced by itself.

Later, everyone would follow this configuration out the window and get

poor results. This was our big mistake. But we also knew at that time

that the step worked in different configurations and we couldn't patent

them all. All we wanted was to patent a step in the hopes that it would

produce stall resistance to other airfoils. All the experts trashed

this idea as too high in drag, yet the KFm4, with a step on the top and

a step on the bottom, increases the speed of the wing. If the drag was

so high, how could this be?

All in all, it has been a wonderful adventure and I feel very grateful

and lucky for it. I have come in contact with many truly wonderful

people in the RC community. From my perspective, the world could take

some lessons from the RC people on how to work together, how to openly

share information and knowledge freely and produce an environment of

creativity and experimentation. This way everyone benefits and the

learning curve climbs way up for everyone.

The gentleman who conducted these tests at Notre Dame was Professor

John D. Nicolaides, the first head of NASA.