[papatango]

On a trolley, is it simply drop away gear? Or do you use a bungee system for additional power??

Is a portable catapult an option?

[Guest]

The easiest way is to simply push two spikes into the ground and stretch out a bungee. Whats with all this talk about dollys. Almost every Foam jet Ive ever seen is hand launched anyways, unless your useing a larger and heavier battery, in wich case i use the bungee. Composite jets will almost always require a bungee and then even a dolly attached to a bungee, as some people prefer. But foam? Just through it in the air.

[Tomahawk]

Double post.

Chris

[Tomahawk]

Originally Posted by ken park

The real question is there a good universal simple design for dolly's for EDF jets? From what I see it would be fairly easy to convert that basic design into a laser cut wood kit using light ply and dowels. The big head-ache seems to be the stearing issue.

Would a large vertical fin on a 3 wheel tail-dragger system with a swival tail wheel work? The vertical tail fin would cause it to weathervain into the wind all the time?

Actually Ken it is quite easy to convert my dolly over to a stearable system. There was going to be a Mk II if I had issues tracking the dolly straight down the runway. I still might do this.
I would remove the front wheels and add a stearing system by Goldberg with a proper size wheel. Attach a servo along the dowel and hardmount the plug somewhere near the index pin. I would then run a lead from the rudder channel on the rx and hard mount it through the bottom of the jet. When you mate up the dowel to the jet it would plug in the stearing servo. Also I would remove the jacket around the servo lead so the three pins would be exposed and this should easily unplug when the jet leaves the dolly.
Here are some pics that I found to explain.

Hi Vettster, I really wanted to get away from lugging all the equipment for the bungee to the field. While two stakes and bungee are basic, there is the launching platform and launching peddle which most also use. Setting it all up is a royal pain. Yes I have one!
The dolly is easier to transport and setup. Small jets I agree, just toss them but I feel that dollies have their place. Jets will be increasing in size and we all know the joys of retracts.

Chris

[ken park]

I really like what I see here with this arrangement. It gives me a good starting point to work with if I wish to build one for myself. The problem we have with our club is if we wanted to set up a bungy we normally have to go way off far from everyone so the launcher won't get in the way of other pilot. This ment a long walk off the field while the jet was flying mostly walking backwards. The dolly on the other hand could be quickly picked up by a buddy quickly after the launch.

I agree that the newer EDF jets and good retracts are now becomming the norm so dolly's and bungy's days are surely numbered.

[LuvEvolution7]

I think the dolly is a great system, but have you had problems with the plug not detatching itself on launch? could you not use simple magnets to overcome this problem? solder your servo wires somehow to the magnet and also to the magnet in the plane, then just connect the dolly magnet to the plane magnet, which then disengages on rotation. just a thought that may or may not work. LOL.

[Tomahawk]

Originally Posted by LuvEvolution7

I think the dolly is a great system, but have you had problems with the plug not detatching itself on launch? could you not use simple magnets to overcome this problem? solder your servo wires somehow to the magnet and also to the magnet in the plane, then just connect the dolly magnet to the plane magnet, which then disengages on rotation. just a thought that may or may not work. LOL.

I have never had a problem of the pin sticking. The hole is a little oversized. Just make sure the pin is long enough so the jet doesn't accidently jump off the dolly from a bump before it reaches takeoff speed.

Chris

[LuvEvolution7]

makes sense to me too. might give that a try for my Eurofighter, since I removed the UC. it's a little hard to hand launch with so little to get a hold of under the wings. I think I'll just use a straight set up though instead of a steering option.