Powered Parachute 2

The kit shows up in a box about 2 feet square (determined primarily by the diameter of the propellor guard). Lots of pieces of precut wood and aluminum tubing.

Assembly is straightforward, although, the 10 hours referred to in the instructions is probably only true if you are an experienced builder with shop space, and are really efficient.

 

Waiting for the engine

Mounting the engine wasn't too difficult, except for deciding what orientation to put the engine in. Mounting it cylinder sideways would make the carb adjustment screws nicely accessible. The screws are on the "bottom" side of the carb, with the fuel inlet on the top. However, I worried about the uneven CG, so I decided to mount it cylinder up, and hope that I never have to fool with the needle valves. The choke is operated by a simple lever which is right up against the firewall.

The ignition switch is a standard SPDT toggle switch mounted on the engine mount brace.

A real problem is that the fuel tank mounts right under the engine, but if you use permanent zip-ties and double sided tape to hold it in place, it's hard to open it up to refill it. I suppose you could hook a fill tube up that you could pump gas through. Looking over the Sullivan web site, there are a number of solutions (http://www.sullivanproducts.com/FuelSysComponentsMainFrame.htm)

Starting the first time

The ways that don't work:

Hand flipping (not a chance on a cold engine, although it's possible you could hit it just right and get it to fire, especially on a warm engine). It would be scary, too.

Pull rope (hey, it works for the weedwhacker!).. nowhere to put your foot or hand to hold the engine down. Sure spins fast enough, but I couldn't get it to fire.

Improvised electric starter made from a PVC pipe cap, a bolt, and my DeWalt cordless drill. Can't turn it fast enough long enough to reliably fire. You can run it long enough to flood the carburetor (at least I knew that fuel was getting to the engine from the tank)

The way that works (9 July 2003)

A standard Sullivan electric starter. It's basically an electric motor with a cup and rubber insert that fits on the prop spinner. Works like a champ. That 5500 RPM noload speed is important! Don't fool with anything else.

I ran it the first time without a prop (avoiding the whirling blades of death problem). Runs fine at full throttle and can go down to around 2000-3000 RPM before it quits.

Put the prop on (APC 18-6WP). Starts right up, and is running smoother (a bit of break in as well). At full throttle, the prop blast shakes bushes 30 feet away, and it will drag a concrete block across the driveway. Idle is a bit trickier, and the engine dies well before the end of the travel. Since the forward speed of the PPC is fixed, you need to be able to turn down the thrust to descend. Probably some experimentation called for? And, then, maybe I just need to adjust the needle valves.

Vibration is phenomenal. screws and nuts falling out all over the place. I'm certainly going to have to look into vibration mounts for the engine, and certainly the electronics or it will just get beaten to death. Dynafocal mounting maybe?

The spinning prop is totally invisible except at very low speeds where the fluorescent lights create a stroboscopic effect. A prop guard is essential on this. I think video is deceptive, because it actually makes the prop visible (probably a stroboscopic effect)

robot/ppc/ppc2.htm - 10 July 2003 - Jim Lux
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