Posts Tagged ‘KF Airfoil’
(Post updated 10/6/09 with new graphic from Dick Kline. Now includes 9 KFm Airfoil Variations. See below)
I just wanted to post a new graphic that Dick Kline was so kind to share with me. As many of you are probably already aware, Dick Kline the inventor of the KF Airfoil is always tuned into how we in the RC community are using his cool invention. Mr. Kline also enjoys creating computer graphics of many things. Well recently Dick Kline sent me his revised graphic that depicts the well known variations of the KF Airfoil as well as some new versions that people are experimenting with. Dick wrote me a few brief emails below with the attached graphic. I wanted to post it here and share it with the rest of the RC Community and all that may be interested.
Here’s the Emails:
I wanted you to have a copy of the visual I came up with showing all the different variations of the KFm Airfoil Family. They have multiplied like rabbits.
Well, two more additions have arrived. One is an under-camber with the step on the top. So, that goes next to the under-camber with the step on the bottom. I’m told that they both work extremely well.
So, here’s the KFm Family of nine airfoils…
(Here’s the graphic made by Dick Kline, many thanks to him for providing it!) (updated 10/4/09)
Click on the image to Download a PDF copy.
Later I will try and get some written descriptions of each Airfoil and what benefits each provides. So please stay tuned, we want to keep this blog going as a good resource for KF Airfoil information.
If anyone would like to contribute their findings on the KF airfoil please feel free to email us at firstname.lastname@example.org. We are hoping to help Dick Kline spread the word of his cool invention and share the collective knowledge we all have.
Happy Flying to all,
I just wanted to add a post to the blog on the Jupiter Project that we are just starting. This project is a collaboration with Dick Kline (the Inventor of the KF Airfoil) and rcFoamFighters. The original idea for this project started with a suggestion from Dick Kline, he asked if we could do a project that will compare the KFm3 and Clark Y airfoils.
Here is a brief intro to the project written up by Dick Kline:
THE JUPITER PROJECT.
When we filed for a patent on a stepped airfoil back in 1970, Dick Kline and Floyd Fogleman were hoping that it would be seen as a concept worth investigating because of the stall-resistance built into this idea. The Kline-Fogleman airfoil has many favorable characteristics that we felt could be investigated. However, we were met with a wall of resistance from all the experts. It was a terrible idea as far as they were concerned.
Our patent drawings, which showed a sharp leading edge were followed out the window in their wind tunnel tests. However, they were also applying conventional testing methodsto an unconventional airfoil. For example, there wasn’t any testing for a forward push directly behind the step. There was no camber applied along with a rounded leading edge. Our intention was to patent only a step, not an entire airfoil shape, because we knew that it worked in various configurations whether it was on the bottom or on the top. We chose to show the step on the bottom because we knew that L/D ratios reverse themselves when you go from subsonic to supersonic flight. And, we knew that the L/D was higher when the step was on the top, based on wind tunnel tests done at Notre Dame. Therefore, supersonically we would pick up the higher L/D ratios. So we showed the step on the bottom for that reason.
In a book called Fluid Mechanics by Frank White, he shows a number of NASA airfoils producing lift, then reaching a stall point. He also includes the KF airfoil which continues to generate lift out beyond 50º AOA even though it showed a flat upper surface and a sharp leading edge. Although this is a remarkable characteristic of stall resistance, none of the experts thought that it was worth investigating.
The KFm airfoils were embraced by the RC community starting in 2006, because Tony Bernardo decided to try a KF airfoil out for himself. He started a thread which is still going strong and has many contributors to the development of the KF airfoil concept. Today, people from all around the world have accepted the KF airfoil into their building techniques of RC aircraft. What they found was a very easy wing that they could build. Very inexpensive. Very strong. Very high in lift. And, very stall-resistant.
The acceptance of this radical concept still meets with great suspicion and disbelief. “It shouldn’t fly because it doesn’t look like a normal airfoil. It can’t work. It produces too much drag. It won’t fly.”
I have proposed an idea to the RCFoamFighters. What if we could demonstrate that a KFm3 airfoil can lift more weight than the icon of all airfoils: the Clark-Y. Wouldn’t that help to convince people that there is some merit to this radical idea of a stepped airfoil? If it can be demonstrated that the KFm3 can carry a heavier payload along with its ability to resist stalling, it should warrant a more in depth investigation, in my opinion.
Several years ago, Rich Thompsonproduced a comparison study between several KFm airfoils, a Clark-Y and a symmetrical airfoil. The KFm2 and KFm3 came out with very high marks overall. But this did not impress the people who are the experts. Maybe a real world weight-lifting test would persuade them to take a second look?
Who knows. Only time will tell.
In the meanwhile, what is known is that the KFm airfoils work extremely well in the UAV arena. That has been demonstrated successfully a number of times over. It takes a leap of faith to trust your camera, motor, batteries and servos to a strange-looking airfoil that is not supposed to work in the first place. And, have that aircraft return to you safely with all your precious equipment intact. Now, who wouldn’t want that advantage?.
After a few emails back and forth to Dick Kline, I developed a concept for the plane we could build for this project. We both decided it would be neat to build a plane in the style of a large Military Cargo Plane. Below is the Concept Drawing of the plane we will be building, the C-54KF Jupiter:
So in the coming weeks I will begin to build the plane out of EPP Foam. Once we get the plane built and flying good we will run it through a series of tests and comparisons with the KFm3 airfoil and Clark Y airfoil.
Last, here is the first video in the Jupiter Project Video Series:
I just wanted to do a quick follow up post on the new “KF Condor RC Plane” that I posted video of on our YouTube Channel. A few months ago I bought the book Dick Kline wrote, “The Ultimate Paper Airplane” . It’s the book where Mr. Kline tells his story of how his paper airplanes lead him and his friend Floyd Fogleman to the invention of the “KF Airfoil”. It’s a really good book that tells about the theory of why the airfoil works and also tells about it’s wide range of flying benefits. The book tells of the many shows and articles that Dick Kline was interviewed on and for. From David Letterman to 60 minutes, Omni Magazine and so on. His airfoil was even tested by NASA. Dick Kline also has a patent for this awesome invention.
There are many people who have tried the KF Airfoil with good positive results, including my brother Frank and myself. We have both noticed a real difference when comparing similar planes with and without the KF Airfoil. The biggest good benefit I noticed was the slow speed stability of the KF airfoil equipped wing. Also the KF wing was much more responsive, I believe because the KF airfoil keeps the air over the control surfaces better. This is all just my theory, but something we at rcFoamFighters want to explore more. And thankfully we have a new, good friend to help us, Mr. Dick Kline himself.
So, having said that, my next project I have decided to build with a KF airfoil will be a plane inspired by one of Dick Kline’s Paper Airplanes, The Condor. This plane will basically feature a KFm2 airfoil to resemble the wing of the paper airplane. I really like the look of this paper Airplane because it is unique with the smaller wings on top and rear of the fuselage. So I have drawn up a basic template for the plane in AutoCAD and I am now beginning to build the plane, so please watch our YouTube channel to see how it all goes.
Below I just wanted to share some pictures and a short write up Dick Kline himself sent me about his amazing plane, the Condor.
(below picture) Dick Kline with his Condor paper Airplane and a Wright Bros Replica Model
(Short email about the Condor from Dick Kline)
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.”
Another picture of a version of the Condor
Here is a picture of the RC Plane I plan to make. Note that the RC plane will more resemble the Condor Paper Airplane version as pictured in Dick Kline’s book “The Ultimate Paper Airplane”. The Verison in the book appears to have a little different tail and the small wings on top of the rear of the fuselage appear to be larger. Anyway, here’s my attempted to make a plane in the style of the Condor.