Flight

Well, it's time to put Bernoulli's principle to use. We managed to get out during a brief time of unusually still air. My usual flying field gently slopes south which makes use of the predominant wind here. The grass is now about 6 inches tall and a few small gusts of wind were coming out of the southwest.

 

This is the very first flight of the Cypselurus. Having flown mostly stocky Art Hobby planes this light little glider seemed almost buoyant. It easily flew a hundred yards while I weaved from side to side testing the controls. I gave it more rudder throw but the elevator seemed good. Nice launch!

Several times I saw it just gain a few feet of altitude out of nowhere. For a hand launch, the flight times are great.

I wondered if the wings would be overloaded with the R/C weight. They flex slightly while flying but not so much as to be a problem.

In the picture above, the grass on the other side of the trees is the dam of Clinton Lake. When the wind's from the East, it provides good slope lift. I think it will be enough to keep this plane airborne indefinitely. Assuming, that is, that we get an East wind, which we never do.

 

Ground effect
After some hand launches we tried hand towing. I should say my grandpa tried hand towing; I just piloted. We've had success with another glider which I modified to tow, although we couldn't get this one to work. The hooks I made are way to small and the line fell off every time right when I let go of the plane. I'll replace them and then I expect long flights from towing.

As for flight characteristics- although it would be a bit fragile for a first time pilot, it's easy to fly. A good pilot could easily keep this in the air with a steady supply of thermal assistance.

Comments

[Tom Martin]

Nicely done Scott! I was just down at the dam at Clinton a few weeks ago. I had no idea you lived so close and right here in Missouri. Sometime we'll have to get together and fly the lift off the dam. Do you think the Corps will let us. Some lakes they don't allow any loitering on the dam, yet at Wilson Lake in W. Kansas it's no big deal and they welcome slopers. We could fly the west side but we'll have to be careful.

Tom

[Armando Gama]

Scott,
I am a newcomer to the art of sailplane buidling, so I am interested in as many things I can learn of the aspects of Designing, building and, of course, flying this amazing displays of human ingenuity.

This said I'll go to my comment-question:

-You forgot to say how much is the Total flying weight of your Thermic 50X.-

[Svoigt21]

Short Answer:
It's in the very first post with the other specs.

AUW = All Up Weight = 7 oz

Long Answer:
It's 7 oz, which is very heavy. The plans list the "Normal Weight" for this glider as 4.75 oz. As a free-flight to R/C conversion the increase in weight is hard to avoid, but the extra strain on the wing really shows in flight. In fact, I just finished rebuilding the wing after it snapped while flying in too much wind. If I were to build another Thermic, I'd replace the wing spars with stronger wood to accommodate the additional weight.