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Old Nov 29, 2004, 09:52 PM
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weight shift micro helicopter

I have been out of RC for a while and am just getting back into it.

I am intrigued by the use of the zip zap motors. I wouldn't have estimated them to be powerful enough to base any sort of rc plane on, no mater how small the rc system was...

ok, so here is the idea, I don't know if it feasible or not, but does anyone remember the weight shift helicopter plans that were sold in the back of old Popular Science magazines (maybe they are still there but I haven't read PS in years.) The basic layout was like a helicopter but with rotation of the blades powered by propeller engines that spin with he blades

propeller engine/motor
.......................|=
.......................|
..............blade | blade
.... ========0=========
....................... |
....................... |
.......................=|
................propeller engine/motor
top view

It presumably doesn't need a tail rotor since the only torque on the main body is the drag of the bearings any spin could be countered with a rudder and a little forward velocity

Thought would have to be given to the propeller design and to the distance of the engine from the axle. also power would have to be transferred through the stationary axle to the spinning motors (possibly by using motor brushes?)

control: I have no idea how far to put the bulk of the weight below the blades. control might be accomplished by shifting the battery pack and receiver with the rare earth magnet actuators...maybe. One could also use an ESC for the motors but throttle response would be very slow. I am not sure if one could make a collective control light enough though. Electronic wing warping maybe? blades framed by carbon fiber and skinned with balloon rubber so that the wing warping can occur mechanically?

I might be able to do some work on propeller and rotor optimization if someone understands my gibberish and thinks the idea has merit. I don't think I can afford right now to do a full fledge project though. Also, the props could be placed in the rotors themselves instead of on separate structure might be beneficial. anyway...thoughts?
I'll try to draw something up to make it clearer.
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Old Nov 30, 2004, 07:40 AM
4-D traveller
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The Hoverfly is an implementation of such an idea which I think is inferior to the conventional heli design.
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Old Nov 30, 2004, 12:02 PM
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the hoverfly doesn't appear to have blades and is just using rotation for stability. I intend to have the motors horizontal and use them to spin the blades to create lift. It might be a good idea (cheaper for now) to create a teathed model and simulate the weight of electronics. Thanks for the idea.

I can't envision this power system to be more efficient by any means than a direct drive system, but that doesn't mean that it couldn't be a better solution (read: lighter, easier to build) for a 6" wingspan helicopter using pager motors as propulsion.

heck, it even might be able to fly as well as spin around and look goofy.
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Old Nov 30, 2004, 12:36 PM
4-D traveller
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Quote:
Originally Posted by grindel
... I intend to have the motors horizontal and use them to spin the blades to create lift.
Interesting, only problem is it can be hard to get enough head speed, or the motor prop tips have to go supersonic?

Quote:
Originally Posted by grindel
I can't envision this power system to be more efficient by any means than a direct drive system, but that doesn't mean that it couldn't be a better solution (read: lighter, easier to build) for a 6" wingspan helicopter using pager motors as propulsion.
Not necessarily less efficient if the blades are long and huge. But you need hub brushes to supply power for the motors, increasing tear and wear. All in all, this configuration has many more moving parts than a conventional design.
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Old Nov 30, 2004, 01:05 PM
Scarecow
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what you need is tiny tip-jets like this full sized version.
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Old Nov 30, 2004, 01:08 PM
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they are developing nano jet turbines that could be used to replace batteries in the future.....this would be ideal although a few years away.

found a link...

http://www.newscientist.com/news/news.jsp?id=ns99996559
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Old Nov 30, 2004, 08:22 PM
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Quote:
Not necessarily less efficient if the blades are long and huge. But you need hub brushes to supply power for the motors, increasing tear and wear. All in all, this configuration has many more moving parts than a conventional design.
I don't see how this has "many" more moving parts than a standard helicopter...really, the hub brush design doesn't seem to be a show stopper to me...power could be even transfered through a set of ball bearings using no brushes. The battery could also be located at the hub and spin with the blades...although this would require the reciever to have its own battery.

anyway, enough conjecture

Ok...other informed oppinions? any guess about feasibility? How about blade design? where can I get good pager motors?
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Old Nov 30, 2004, 08:50 PM
Blade Springs "Rock"
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Joined Apr 2004
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Well, let me pipe in.........this project is really a multi-rotor design.......in the wrong thread......for sure.....but if you want the best of the best.......motors and electronics for micro controls.......start here: www.homefly.com.

G109
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Old Nov 30, 2004, 09:21 PM
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meh...ok...whatever

anyway, thanks for the opinions.
good link, too pricey for me for something that might not work very well
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