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Old Dec 22, 2012, 02:22 PM
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Joined Apr 2012
80 Posts
Idea
The hunt for speed...

I'm starting to get tired of my friends mocking me when the fly their pylon-racers and HK funfighters at silly speeds for foamies, so I've decided to mock them some back. This project is in the planning-phase at the moment and I'm turning to the bunch of you here for some advice and out of the box thinking, so I can get my machine to archive much much higher speed then any of my previous multi-rotors.

I've decided to go with this frame; http://www.hobbyking.com/hobbyking/s...rame_KIT_.html - It's a cheap HK-frame, but the body looks quite a bit sleeker and I imagine it's gonna work quite a bit better then a regular frame with lots of drag. As for motors and esc's, I haven't quite been able to nail down what I want yet, the only thing I'm dead set on is that it's gonna carry a MultiWii board with GPS.

The question therefore is - If I go with high pitch props and high KV motors (possible up to 1600-1800kv and 4s setup) what problems might I encounter? Would it be unstable due to being less effective at lower rpm's? What about turning, could I even sustian a controllable banked turn with say 6x8 props? What should I do to prevent overheating of the ESC's? I imagine the ESC's are gonna get pretty hot inside the skin...

All thoughts are very welcome, I'm not new to multirotors but I haven't tried this approach before...
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Old Dec 22, 2012, 02:33 PM
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New Zealand, Canterbury, Christchurch
Joined Dec 2012
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I would guess you'd want to overspec the ESC's as much as weight and room will allow to offset the heat issue. I hate to think what your flight time will end up being though
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Old Dec 22, 2012, 02:40 PM
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Quote:
Originally Posted by WendoNZ View Post
I would guess you'd want to overspec the ESC's as much as weight and room will allow to offset the heat issue. I hate to think what your flight time will end up being though
I couldn't care less if I get 4 mins of flight time, the point to this project is to stop some mouths
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Old Dec 22, 2012, 02:52 PM
jab
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Joined Aug 2007
1,055 Posts
A tri-copter and small propellers is the right approach, since you need the small propellers for speed but most likely will need the rotating tail motor to be able to turn (not enough torque force).

I think ideally you should be able to rotate the two front motors forwards during flight, so that you don't have to angle the copter so much to generate forward motion. This would help preventing drag.

One problem might be stabilization with small high rpm propellers. At pylon racer kind of RPM speeds, the propellers might have to much rotational inertia for stabilization to work.
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