Tuesday, November 18, 2014

Cessna 150 Flies and Cessna Died

Not all of my model building projects turn out well, I do try to learn from my mistakes and do better on the next project. On the first conversion of a rubber powered free flight model to electric RC, the Guillow’s DHC-2 Beaver I went into the project with no prior experience with these types of conversions. After the initial problems the airplane flew very well and I think maybe it gave me over confidence for the next project, the Guillow’s Cessna 150.  

Cessna 150 Before Crash Testing

For the new conversion I had a more powerful motor/ battery combination and greater weight although I never weighed the airplane. It felt light and had plenty of power to climb, maybe too much. It was getting towards the end of the flying season and I rushed to get it in the air. The first flight didn’t seem too bad until the wings ripped off the airplane. On trying to fix the airplane and strengthening the wing joint I did not put in enough dihedral and the plane would not turn properly.

Cessna in Flight

After one flying session I grabbed each wing half and broke the wings partially loose to add more dihedral. The wings were still fairly solid on the plane so I flew it that way and it turned better. Repairing the joints with added dihedral the plane still did not turn well. It would appear to not be responding and then go into a spiral dive. Sometimes it didn’t recover before hitting the ground.  The plane never did fly super stable like the DHC-2 Beaver had. After so many repairs, I gave up. 

Wing Halves Bent Up

About this time I purchased the eFlite Sbach 342 which used the same batteries and charger as used in the Cessna. This airplane is a real performer for something so small, it does nice big loops and axial rolls. I wanted to do something with the equipment from the Cessna, so I looked through the treasures in my basement. I found a really lightweight wing structure that my friend Floyd Richards had given me, it was a symmetrical airfoil that was thick and had a good amount of wing area.

RTF Sbach 342

The idea was to build a nose on to the wing for the electric motor and add a vertical fin to build a flying wing. I rushed this project and went out to fly without checking the direction of the elevons. Sure enough this was backwards, when I fixed that the elevator action was backwards. At this point I was forced to read the manual to get it working right.

Flying Wing

It was starting to turn cold and darkness was coming early, if I was going to get a test flight in early morning would be the only time.  With little time to fly before going to work, I flew over the street in front of my house. It flew really well, stable but yet agile.  The wing needs to be recovered as the clear food wrap just isn’t strong enough. I am looking forward to flying this plane more, maybe indoors in a gym where it is warm.

Bill Kuhl

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Only Video of Cessna Flying

Monday, November 3, 2014

Dynamic Soaring Weekend

This past weekend the winds were in a favorable direction to try dynamic soaring from a small ridge that I had some luck with DS flying one previous time.  On Saturday the wind was SSE around 10 mph, ideal direction is south or north. I tried the Alula first to see if I could possibly get it to DS, I had watched videos of Soren Jensen ds’ing the Alula but he makes everything look easy.

Slope Facing South Wind

North Facing Side

Super Scooter on the Backside

After some front side flying with the Alula I gained altitude and made a run over the backside, circled the bottom and made it back up to the top. That was the first time I made it back to the top but when it went down again must have pulled too hard as it crashed in an awkward way breaking the tail. No filament tape along so had to repair with masking tape, but that held for the rest of the day.  I never got more than three circuits but I got in lots of practice diving over the hill which was the first thing to scare me with DS.

Cracked Tail on the Alula

Next in the air was my Hyper DL which is the first plane I had success with on this hill.  It keeps the energy well through the circuits but I kept going off course, maybe because the wind was not exactly straight into the hill. Sometimes I must have pulled up too hard on the bottom of the circuit and the glider was shooting straight up, it worries me more not pulling up enough and crashing into the hill. I really don’t want to break this glider because I enjoy DLG thermal flying with it.  It was really fun trying DS again and I am slowly getting more comfortable with it.

Hyper DL

Sunday’s forecast was for south wind with gusts up to 35 mph, I don’t think it was that windy but probably a good 20 mph. This time I brought out the Super Scooter which flies well in high wind but is a much heavier wing loading.  There were times it was a struggle staying up on the front side but other times it climbed fairly high and then I would dive just barely missing the top of the hill. Controls were really too sensitive for DS and the first circuit it got inverted on me and I stuffed it in the ground. Still only masking tape for repair but I had it flying again quickly and got some multiple lap DS circuits.

Busted Nose on the Super Scooter

Took a break for lunch and came back out to try it again.  With the Super Scooter I couldn’t go as far down the backside but I was coming out farther to the front side.  I kept getting braver and came closer to the top of the hill but on the bottom turn often it would be too high and get blown off course. On one occasion I definitely heard the sound of the glider passing through the boundary layer, what a thrill.

 Several years ago I had the opportunity to fly DS on a much larger hill and it was easier but this hill does make it possible and pushes me to improve the technique.  The more I fly; the better I seem to be able to judge the energy level of the glider.  It is one thing to fly a powered plane in horizontal circles close to the ground but harder to fly circles low to a hill that is at a steep angle.

I am feeling the addiction of this challenge pulling me, like others inflicted with the DS addiction I am starting to feel flying on the front side of the slope is a little boring.  My goal this year was to make more than a single DS circuit on a small hill, next flying season I am going to shoot for a dozen or more.

Bill Kuhl