I recently tested a new 6S power system for my FF-Demon foamboard RC plane. I was looking for something to push the plane over the 100mph mark. Frank recently tried the T-Motor F90 Pro drone motor on his Strix Goblin RC plane. After seeing how it worked out on that plane I decided to try it on the FF-FF-Demon. The F90 motor I used is a 2806.5-1300kv motor. Note it is also available in 1500kv, version which I already have and will test in the future also. One other thing to note, drone motors usually do not come with an X-Mount. So you may have to source an existing one, buy one or make one. I had some old motors with X-Mounts and found one that fits. The F90 Motor has mounting screw holes at the 19mm x 19mm diagonal spacing. For the ESC I used was a Cobra 60A Race Wing ESC with the BLHeli Firmware. For the Test I got a couple of cheap HRB 6S 1800mah 50C batteries. Props used were APC sport props, sizes 7x6 and 7x5. I was pretty happy with the results. The FF-Demon hit just over 120mph, though with a good tailwind. I think that is pretty fast for a simple foamboard RC plane. I plan on doing some more tests with a few other props, maybe something like the APC 6.5x6.5 Pylon racer Prop. Link to the F90 Motor: T-Motor F90 1300KV/1500KV Motor (getfpv.com) Link to the 60A Cobra ESC: Cobra 60A FPV Wing ESC with 6A Switching BEC (innov8tivedesigns.com) Link to Batteries used: https://amzn.to/3lMf57G

I finally got around to putting a 6S Power System into my FF-Demon RC Plane. I ended up choosing a T-Motor F90 Pro 1300KV drone motor, with a Cobra 60A Race Wing ESC with BLHeli firmware and an HRB 6S 1800mah 50C battery. I tested the power system with a n APC 7x6 Sport Prop and 7x5 Sport Prop. The high pole drone motors work best if you use a BLHeli ESC, they are much better a keeping up with high Pole motors at high RPMs. Below are links to the parts and the video of the Maiden Flight with the new power system. In the video the plane hits a GPS clock of just over 120mph. Not too bad for a foamboard plane! Link to Motor: T-Motor F90 1300KV/1500KV Motor (getfpv.com) Link to ESC: Cobra 60A FPV Wing ESC with 6A Switching BEC (innov8tivedesigns.com) Link to battery: https://amzn.to/3lMf57G

Below is a brief story Dick Kline emailed us in 2009 about the the KF Airfoil and Condor Airplane: ----------------------------------------------------- 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.

Below is a Diagram of some of the different types of KF Airfoils Dick Kline sent us back in 2009. There are even more variants out there now. Please feel free to post about any KF Airfoil variations you may have used or seen.

Below is an email & PDF's Dick Kline sent us back in 2009. Email: Hi Frank and Paul... I have just written this piece as to why I think the KFm3 airfoil is a heavy lifter. I would like you comments on it. And, please let me know if you disagree with it. Or not. There has never been any official explanation as to why the KFm airfoils work in the first place. Only conjecture. So here it is, and if you feel you want to post it, go ahead. But only if you think it is spot on. Hope all is going well for you guys. – Dick

Has anyone tried any of the BadAss Motors available at https://innov8tivedesigns.com/ I just got a new BadAss 2826-1360kv motor and a 100amp Cobra Race Wing ESC. Motor is supposed to be rated up to 2100watts on 6S Lipo, up to 95Amps continuous. Hoping to test it out soon. I might put it on my old FF-SuperNova if it tests out to be more powerful than the old motor. Definitely looks to be of way better quality than the old HobbyKing 3648-1450kv motor... The motors are roughly the same size, the old Hobby King motor numbers are by outer can dimensions, the BadAss motor is by inner Stator size..