Thursday, October 27, 2016

Making Progress in E36

I remember reading the book by Frank Zaic, “Circular Airflow” not really understanding it but amused by his struggles designing a glow powered free flight that would not loop or crash after launch. It really is amazing to me that a free flight airplane can climb so quickly under power and transition smoothly to a slow glide, but not always. My first attempts at a fairly fast powered free flight were when I installed the electric power system I had purchased from Texas Timers for e36 class in an old ½ A glow powered Starduster.  The balance was guessed at and tweaked from test glides but the airplane flew pretty well although I did not build this model.

Pearl E202 at North Branch

The intended model for the electric components was the very popular Pearl e202. As locally I had a very small flying site I added rudder control RC to the model for the first flights. With my inexperience I did not have the stab incidence adjusted correctly and managed to crash the airplane even with the ability to steer it. With enough incidence it flew fine but I needed to fly it as a free flight model. Just before going to the 2016 Free Flight Nats in Muncie Indiana I removed the RC gear thinking I would have plenty of room to fly and many people to help me.  I did have the room and help but a recurring problem was that the plane had a tendency to dive to the right after the top of the climb. 

Lots of Help at 2016 Nats

After returning to Minnesota I flew the plane before two contests near North Branch Minnesota. At the first contest there were some less than perfect power patterns that barely avoid crashing. For the second contest I launched to the left which should not work but it did for some strange reason. The plane was launched to the left for many flights but on occasion there was a small stall on top of the climb. A couple of weeks ago I was flying the Pearl from some farm land and I noticed a crack in the stabilizer leading edge, the trailing edge was warped also.  More flights launching to the left were made after the repairs but then I thought I will try launching to the right with a short DT. That looked pretty good with no dive. Awhile back the plane came down so fast launching to the right that the wing folded in half as it DT’ed just before hitting the ground. I tried more launches to the right and the transition was great.   DT dethermalizer a method for bringing airplane down from thermal air current. 

Wing Folded on DT after Dive

DT over Farm Land

I sure hope I have permanently found and corrected the dive to the right issue. Most everyone with EXPERIENCE have told me launching to the left is going to cause a crash. For me there is no reason to try to prove them wrong. Hopefully I can have many more great flights launching the airplane the way it should work.  E36 is really fun and I will be building a different model a Starduster E36 which should launch to the left because of the high thrustline.

Bill Kuhl

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