Cross-Country Soaring with a Rabbit
The case for not using a retriever line when using a dolly.
I love cross-country soaring. To me, it is the best type of soaring with the most fun shared with friends working together as a team and competing against each other. Driving down the road with the wind in your hair, your hat strapped on, and using your transmitter as a bug deflector is just, well, fun! Pro tip: keep your mouth closed.
I also like the older style cross-country sailplanes. Recently, I found someone selling one of these nearby. This sailplane was a Bob Sealy Catalina and probably built in the early 90’s and was rudder, elevator, and flaps. She had wear on her but still had a lot of good flights left in her. So, I bought her, took her home, and updated the radio gear, fixed a couple minor cosmetic and functional items including new batteries and a state-of-the-art telemetry system.
Off to the field I went with this beauty and set off for the mandatory hand tosses to ensure the balance was right as well as the elevator neutral setting. It was during these hand tosses that I realized my aging shoulder would no longer tolerate throwing a 4kg (8.8lbs) sailplane while hanging onto the transmitter in the other hand. Doing this on a winch seemed even more troublesome. The original owner had recommended against rise-off-ground (ROG) launching because he had experienced bad results from it. So, I was stuck with how to launch this plane by myself at a field for practice. The solution was using a sailplane dolly for launching the sailplane.
A quick message to my friend Tom Broeski — and fellow RCSD author — and the Rabbit Dolly was on its way to me. Now, for those that might not know what a sailplane dolly is, let me briefly describe it. It cradles a sailplane on the ground in a flying attitude. The dolly has four wheels, though sometimes there are three-wheeled version available. Tom’s dolly, the Rabbit, had one central axle instead of a front and rear axle and this allowed the dolly to run over uneven grass that may exist on the flying field.
The idea is that you rest your sailplane on the dolly, connect the winch to the sailplane and then as you step on the pedal to activate the winch, the sailplane’s weight pulls the dolly along. Once the sailplane’s wings have begun to fly, the sailplane rotates off of the top of the dolly and the sailplane is being winch launched in the usual fashion from there. That’s the theory. But being an engineer, I know that in theory, there is no difference between theory and practice. But in practice, as we all know, there is a difference
So now let’s talk about the real world.
The field I fly from is not so much of a flat field as you might think. In fact, it is the somewhat flattened top of a capped landfill that the local club has secured as a flying site. But as you leave the groomed field top, the slope all around the field goes downward at about a 50 degree angle for more than 100ft then there is a solid rock trench surrounding the landfill. Yes, they cut down until they got to the bedrock. After the bedrock trench, the slope goes upward again at a less steep climb until you are level with the original field.
Mind you freshly excavated rock has sharp edges. We string our winch from the top of the field’s side of the land fill across this chasm and up the other side until we are level with the winch. This takes about 300m of line out and 300m of line back. To keep the winch line from falling back into the chasm after a launch and dragging against these sharp rocks, we use a hands-free retriever. That also saves a trip down the slope to fetch the chute. As soon as the sailplane releases the winch line, the retriever is activated and drags the lines back to the winch before they fall onto the sharp rocks.
I called my friend Robert to join me and help out where needed. The Catalina was ready for her first winch launch. The winch was set up in our usual way and a full pedal test flight of the winch with a 4m thermal duration composite sailplane was performed and everything was ready.
“Robert, can you throw the Catalina as I winch it?” I asked.
“Heck no. Didn’t you bring the dolly?” Robert replied.
“Why, yes, I did. Good call, let’s use the dolly” I answered.
And so, we assembled the dolly and placed the sailplane on it and pulled the dolly, sailplane, and winchline back about 20ft from the edge. We were ready. In theory.
Picture the sailplane sitting on the dolly, the winch line attached to the tow hook via a parachute and a retrieve line attached to the end of the bridle. I step on the winch pedal and the dolly rolls forward about 10ft picking up speed and the sailplane leaps for the sky! All good so far, but then the dolly follows the sailplane into the sky. Yikes! How strong is that wing anyway?
The Catalina is not only lifting itself, but also the three-to-four pound dolly easily into the sky. So, at about 30ft off the ground, I disengaged the sailplane from the winch line and the dolly falls not 30ft but 50+ft because it is now over the edge of the chasm and falls to the soft ground on the slope. That small parachute never had a chance. No damage. Apparently, the retrieve line wrapped around the front wheel axle and the rest was history. I was flying the Catalina from a ‘short line launch’ and I asked Robert to get the dolly. Next thing I hear is the retriever running. He used the retriever to pull the dolly, which had landed on its wheels, and winch line back up the hill. At least something worked.
We decided the retrieve line was the problem and used ROG launches after that. First real flight she easily went up to 1,200ft AGL. That’s when I went to full flaps (90 degrees down) to get her down and she still kept climbing since of course, she was in good lift. So, I’m flying with full flaps and the elevator fully deflected for down elevator and the sailplane is holding its altitude. Finally, I released the flaps and elevator and pulled up into a stall. From there, I went into a spin and spiraled down to about 500ft. It was more of a diving spiral than a true spin after the first two turns. That large polyhedral wing likes to fly. I made a note to increase both the rudder throw and the down elevator throw.
Then we heard the sound of an electric ducted fan motor whining and we’re looking for the other plane. But there was no other plane — we were alone at the field. The MonoKote at the leading edge of the horizontal stab had separated the clear top from the color layer and was buzzing in the air as we flew and slowly peeling itself back across the stabilizer. This was the original MonoKote and it was old and brittle. A little tape fixed that — we had more flights to make. On the next flight, the same thing happened to the leading edge of the other half of the horizontal stabilizer. Same fix. I plan to cover those again with new covering, someday. All in all, five great flights easily making it to +1,200ft AGL three times according to the recorded telemetry.
What we learned that day was not to use a retriever line when using the dolly. The Catalina loved being launched ROG fashion. This old girl loves to fly and we needed plenty of rudder and elevator throw to keep her in a spin to get her down at the end of the day.
The Catalina and the Rabbit have become good friends and are stored next to each other waiting for another day to go flying together.
©2021 John Marien
All photos by the author unless otherwise note. Read the next article in this issue, return to the previous article in this issue or go to the table of contents. A PDF version of this article, or the entire issue, is available upon request.
