Tuesday, April 14, 2009

RC plane failures

I've got a Hobbico Swift Flyer RC plane sitting in my basement that I bring out, crash, and swear at every once in a while. It's a decent plane, but it's way underpowered, not particularly durable, and its propellers tend to break. (Of the 8 blades on the 2 props and 2 spares, 7 have broken at some point or another.)
On its first round of flights about 6 months ago, the right wing was creased and several prop blades were snapped off and reglued. On all of those, I was launching it into about a 5mph wind and it made it about 50 feet out and 15 up before flipping over and plunging into the ground. Thrice.
This time was about the same. On the first flight, I launched it straight into a 5mph wind as per the instructions. It went into a 20-foot-diamter loop and crashed, swearing the left wing clean off and snapping both blades off one propeller. I repaired the wing with scotch tape, put another prop on to replace the damaged one, and tried launching downwind. I had several better launches, including one where I pulled it out of its death spiral and it actually landed upright.
I repaired the wing with duct tape and it seems pretty secure, but not perfect, and the props are all in bad shape. One has been retired because it repeatedly threw spit blades duuring testing - the Krazy glue just wouldn't hold.
The next time I try, it'll be in still air and after extensive glide testing, to cure the death spiral. If it works, great. If not, then I've got a couple of options:
1) Buy a new wing and prop set from the manufacturer. It'll probably cost me almost the cost of a new plane, plus it doesn't solve the fundamental problems with it - too much weight and flimsy wing, so I'm thinking no.
2) Make a new wing out of balsa. Cheaper and I could add more lift, but same problems, plus sanding the airfoil from 1/4" balsa would take forever. So no there, too.
3) Add power to the plane, most likely with bigger props. Finding the props might be tricky, but that could work.
4) Buy a new plane. For 30 bucks, half the cost of this old plane, I could get a brand new plane that's far better. Some I've seen have features like autopilot - which'll keep the plane in level powered flight to give your brain a rest - and powerful motors in smaller planes that can do stuff like rolls and loops that mine is simply too underpowered to do. This is the most likely scenario.
5) The mythbusters way: Turn it into a rocket-launched, powered RC plane. Sortof a JATO system. The most likely way I see to do it involves putting a 1/4" launch lug, 18mm or 20mm motor mount, and tinfoil (heat protection) under it belly at the CG point. I'd use a 1/4" launch lug angled at around 45° with 2 3' long rods used to keep the plane upright. A burn string would allow me to start the electric motors, then fire off the rocket motor without the plane leaving the rod under the prop power alone and crashing. Long-burn motors ideal for the job would be the OOP Apogee B2, Estes A3 and A10s, Estes C6s (possibly staged), or Quest D5 (expensive) for basic blastoff, or E6s, E9s, E11s, F10s, F12s, or even a 24mm or 32mm RC RMS system for truly destroying the plane. This would be epically cool, and I may try it if I get another plane. I might take the RC control out first, though, to use for another project, and just have a 12V cmera battery powering it. After all, it'd only last one flight. Man imagine what I could do with this thing with an Ellis Mountain G20....

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