Launch System for Grass
02-26-2003, 12:18 AM
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Launch System for Grass
Hello Jet God's
I'm planning to make a trike gear dolly powered by a highstart to get better speed for takeoff on our rough grass runway. Any suggestions?
1. Big wheels 5 5/8" Dubro Cub wheels
2. Fults Dual strut Nose gear
3. 3.5" front outrigger wheels just above ground level to combat tipping.
4. Chock like cup devices to keep the aircrafts wheels from rolling off the dolly
5. Entertaining on Takeoff for sure.
I'm planning to make a trike gear dolly powered by a highstart to get better speed for takeoff on our rough grass runway. Any suggestions?
1. Big wheels 5 5/8" Dubro Cub wheels
2. Fults Dual strut Nose gear
3. 3.5" front outrigger wheels just above ground level to combat tipping.
4. Chock like cup devices to keep the aircrafts wheels from rolling off the dolly
5. Entertaining on Takeoff for sure.
02-28-2003, 03:26 AM
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Launch System for Grass
I use a similar system for an electric launched 4m sailplane. The bungee launch avoids ground handling problems inherent in the glider - and saves the electrons that would be lost strugging into the air.
I use 50 feet of white marine-type bungee, 3/8 dia - I think. That is staked on one end with one of those corckscrew dog-leash stakes. 25 feet of winch line is on the other end, terminated with a welded steel ring. I tied some contstruction tape near the ring for some drag and a visual indication of the ring coming off the plane. You may want longer and/or thicker bungee to get the plane moving faster than I need for my glider. I originally tried this with a whole hi-start spread across a field - which made for a longer, but smoother launch run. You probably can't make a bungee launch that's too long, but you could end up with one that's too short. :stupid:
For a dolly, I found some surplus 6" stroller wheels. You gotta have big diameter wheels. THese stroller wheels are perfect. They come from the recent stroller types that have dual-wheel bogeys on the front.
For axles I used 3/4" dowel cut to 18" length. I drilled the ends and attached the wheels with lag screws. I used a plain 4-wheel setup.
For the body of the dolly I used a "tupperware" type storage container from Wal-mart($5) I cut holes thru the container sides for the axles and hot-glued them in( before wheels). The top edge of the container can be cut to the desired cradle shape with a sharp knife. Pipe insulation or packing foam slotted and attached to the top edges can be used as the wing bed/ cradle. Part of the cradle needs to come up in front of the wing so the plane doesn't shoot off the front of the dolly.
The hook is mounted in the "chin" position under the nose of the airplane. An HD competition glider hook will work fine. Do not attach the bungee to the dolly. If the ride were to get at all bumpy, the dolly would shoot out from under the plane.
I use flaps and full up elevator until the plane gets off the dolly. I'm not worried that I'll horse it into a stall, since the forward tow hook will keep the plane from rotating too far. The ring fals away about the time the plane passes over the stake.
I use 50 feet of white marine-type bungee, 3/8 dia - I think. That is staked on one end with one of those corckscrew dog-leash stakes. 25 feet of winch line is on the other end, terminated with a welded steel ring. I tied some contstruction tape near the ring for some drag and a visual indication of the ring coming off the plane. You may want longer and/or thicker bungee to get the plane moving faster than I need for my glider. I originally tried this with a whole hi-start spread across a field - which made for a longer, but smoother launch run. You probably can't make a bungee launch that's too long, but you could end up with one that's too short. :stupid:
For a dolly, I found some surplus 6" stroller wheels. You gotta have big diameter wheels. THese stroller wheels are perfect. They come from the recent stroller types that have dual-wheel bogeys on the front.
For axles I used 3/4" dowel cut to 18" length. I drilled the ends and attached the wheels with lag screws. I used a plain 4-wheel setup.
For the body of the dolly I used a "tupperware" type storage container from Wal-mart($5) I cut holes thru the container sides for the axles and hot-glued them in( before wheels). The top edge of the container can be cut to the desired cradle shape with a sharp knife. Pipe insulation or packing foam slotted and attached to the top edges can be used as the wing bed/ cradle. Part of the cradle needs to come up in front of the wing so the plane doesn't shoot off the front of the dolly.
The hook is mounted in the "chin" position under the nose of the airplane. An HD competition glider hook will work fine. Do not attach the bungee to the dolly. If the ride were to get at all bumpy, the dolly would shoot out from under the plane.
I use flaps and full up elevator until the plane gets off the dolly. I'm not worried that I'll horse it into a stall, since the forward tow hook will keep the plane from rotating too far. The ring fals away about the time the plane passes over the stake.
