I'm in the process of building a PVC pedal launcher
If its to bungee launch for speed (jets etc), then well forward is the rule. Gliders on bungee need a softer launch, and a more rearward - maybe towards CG.
For my ducted fan T-33, I had it about 2" in front of the CG. If you move it further back, you will gain more altitude. Since really all I wanted it to do was get it up to speed, I didn't need the altitude. You can see my version of the pedal launcher here:
Did anyone use this launcher for glow engines? I am trying to build something to launch my RC combat planes.
Catapults are regularly used in launching combat models.
refer to
Bungee Launcher & catapult Illustrations - email Alan for Jpegs. Bungymania ***** Catapult - several shown under "Tips,Tricks, Reviews" Dynaflite Hi-Starts Electric winch (12V) - email Alan for Jpeg of winch & turnaround plans. High Starts and Parachutes Histart products and supplies, Dream Catcher Hobby Inc. LiteFlite Engineering Northeast Sailplane Products -- Winch Stuff The Easimore Launching System Winch NZ
As long as the propellor is in the back, I don't see why it wouldn't work.
The main problem with pedal launchers is that the bungee extendes straight out in front of the plane. This is fine for pushers where the prop won't interfere, fine for electrics because you can launch then start the motor after it's clear, and fine for ducted fan planes because they don't have a propeller. Glow engines need to be running before launch, and the prop's gonna chop the bungee in half.
I was going to build a true catapult, but discovered that our 1/12 scale and Open B combat planes over here in the US are so overpowered that they don't need the extra boost from a catapult. All that's necessary is a gentle underhand toss.
Pe, don't you sell MVVS engines? Those are some pretty screamin' engines. They ought to be able to yank the planes straight up and away.
Nice loking model Norm. What motor/fan/battery combo are you using here? getting kinda interested in doing a ducted fan electric.
cheers astroflyer
park flyer plans
This is the Kyosho T-33, with the stock motor and fan. Not bad for $109. I was using an 8cell 2400mah battery pack. In hind sight I would recommend going to a lighter pack, maybe a 1700mah pack. I later upgraded the speed
600 motor with an Astroflight brushless using the same pack. It got a lot longer flying time and could fly in stronger winds. Unfortunatley I don't think they make the model anymore, you might be able to find one on ebay.Yes, they do, once running. In fact, I have a problem keeping the Ki 61 plane speed down to suit my reaction times.
Yet the start procedure is quite hectic, and though the MVVS as I use it starts immediately, it takes some sweet time to gather steam. (no nitro) I may try to tune the engine with 15% nitro to get it going faster. Within our rules with a le-mans start, (run, start engine, get it to rev up, toss), those are valuable seconds taken off the flight duration. With a bungee launch My reconing is as follows.
- warm up engine with plane on the dolly. (batteries + switch on dolly)
- at readiness call, lock dolly in place, turn on transmitter, put throttle at 1/2, walk out the bungee.
- wait for start whistle behind readiness line
- at start, helper runs to plane, throws the glow switch and starts, I grab transmitter and stomp on the bungee pedal as soon as the assistant is clear of dolly.
- the plane launches, and has glow assist whilst on the dolly. Glow disconnects when the plane pulls the plug by itself at the end of the stroke.
- If my launch is quick, I zoom around back along the starting grid, and steal a streamer or two from those wretched pilots that are too slow. (in theory) I may mid-air, and loose the fight though, if my plane picks up too much speed and makes precice maneuvering difficult
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