I want to get the maximum thrust out of less than 2kw of power.

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Soy foxy

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I've seen human powered aircraft using giant propellers to get every last ounce of thrust out of bicycling muscles. I think it would be cool to take off in near silence with no more than some 40v lithium tool batteries and a salvage yard electric motor made from an alternator. Can I actually get enough thrust to power anything more than a parachute, or am I just playing in the land of childish imagination?
 

b7gwap

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You absolutely could hook up your re purposed electric setup to something like the Macready HPV airplanes.
Some considerations, though. Those power reduction systems were incredibly fragile, and were designed for one very narrow speed and torque range. You’d probably have to beef it up. Same goes for the aircraft. Those were proof of concept, one-off, ZERO wind, extremely delicate airframes which, again, were designed for one very narrow speed range.
So, yes. You could do it, and if you want to just to show you can, I say do it. Just know that you’ll likely won’t end up with an electric ultralight. You’ll have a museum piece.

edit: keep in mind that one neat feature of a HPV is that it doesn’t get the weight penalty of a powerplant, fuel tank, or batteries, since all of those things are also the pilot weight. Since the meatbag still has to go for a ride, you’d need to size and strengthen your new design accordingly.
 
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Tiger Tim

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I don’t doubt that it could be done but remember that every airplane is a series of compromises. The human powered airplanes you mention (which are awesome BTW) generally only fly in the most ideal of weather, go short distances in a straight line, require a large ground crew, and are delicate and marginal enough to not fly higher than the pilot is willing to fall.

It’s a neat thought though. If I was independently wealthy I’d probably pursue similar projects but for now it would take more sacrifices elsewhere in life than I’m willing to make. Maybe you’re in the same spot, maybe you’re not.
 

delta

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I've had similar thoughts using low power, but not electric. More like Briggs, Onan, or Honda. the do-ability inspiration came from watching this...

 

rdj

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I've seen human powered aircraft using giant propellers to get every last ounce of thrust out of bicycling muscles. I think it would be cool to take off in near silence with no more than some 40v lithium tool batteries and a salvage yard electric motor made from an alternator. Can I actually get enough thrust to power anything more than a parachute, or am I just playing in the land of childish imagination?
Reminds me of another thread from long ago, when some guy wanted to fly his girlfriend among the drifting clouds in an inexpensive two-stroke ultralight. It's a beautiful dream, but sadly they eventually figure out that nothing screams romance like an unmuffled 10000 RPM 2-stroke turning a 2-blade fan 3 feet from your eardrums.

Even us glider pilots realize that flight can be noisy. That "howling" noise the wind makes during a hurricane doesn't go away just because it's the plane moving at that speed and not the air. Airliners have a LOT of insulation because most people don't like to hurtle along in cold noisy tubes.

But there is a solution; it's called the dirigible. Acquire a sufficiently large bag of helium (hydrogen also works but has some unfortunate "issues"), tie a cockpit/cabin to it, and you probably could move it along quietly with an alternator-driven prop and some lithium batteries. Light-wind days tend to work best.
 

henryk

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could move it along quietly with an alternator-driven prop and some lithium batteries. Light-wind days tend to work best.
dr Sorokodum (Russia) was solved drag ANIHILATION probleme
and big dirigable can fly high speed with very low power (f.e. solar cels...)

the same investigator have got 200 kG /HP specific thrust with simple OSCILLATING wings !

moore= vortexosc.com
 

pictsidhe

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Alternator derived motors have poor efficiency. Get a big RC brushless motor and you'll need less batteries. You'll likely end up with a lighter and cheaper system. To fly on 2kW you will need plenty of span. Look at the HPVs for ideas. As others have said, it will be big and fragile.
 

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