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Alternative Energy Helicopters


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I was just reading about all the new hybrid and electric cars that will be coming into production soon. It got me wondering if there is any similar research being done for helicopters.

 

The only things I've found on the internet about this are a vague reference about military testing and an article about an unmanned fuel cell mini-helicopter. (Links below)

 

Military Testing

http://stinet.dtic.mil/oai/oai?verb=getRec...ifier=ADA375801

 

Mini-Helicopter

http://www.hydrogencarsnow.com/blog2/index...opper-unveiled/

 

Do you think full-size electric or fuel cell helicopters are a possibility?

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The quick answer is no, not right now.

 

The problem with both is weight. For the purely electric, the weight comes from batteries: they simply don't have the ability to store the energy needed. I don't remember all the details, but I once did a back-of-the-envelope calculation where I took an R-22, subtracted out the weight of the motor and fuel, and replaced them with electric motor and Lithium Ion batteries (I think I even replaced the allowable passenger weight with batteries, if I remember right). Using the known specific energy of the batteries, I came up with about 10 minutes of flight time. Flight of any sort, but especially vertical flight is very energy intesive, which is something you just can't get around.

 

For fuel cells, there are two problems: the weight of the fuel containment (assuming you're using H2 as your fuel; there are technologies that reform other fuels, but that adds more weight): whether you're going for high pressure or crygenic storage, or if you want to use metal hydride storage. Also, the fuel cells themselves tend to be heavy. And then there is the problem of fuel supply: if you're going to use a reformed hydrocarbon, it would almost be just as well to burn it outright; if you're going to use hydrogen, where is it going to come from?

 

Unless there is a huge breakthrough in battery technology, fuel cells are the most likely technology to produce an electric aircraft, but I think there's a way to go.

 

Incidentally, when you search online, you might want to see what's going on in the experimental fixed-wing world. Their energy demands are a bit less than for rotary-wing, and I think that there are a couple of project to make an electic airplane that are under way.

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A flying wing is a far different thing than a flying helicopter. Properly designed, you don't need much power to keep an airplane flying. Motor gliders only need the engine for takeoff and landing, and occasional use in the air. They don't go fast, or carry much payload, but they fly. Helicopters need massive amounts of constant power to fly, and nothing else comes close to a turbine engine for power/weight ratios. Piston engines work, but they provide less power for the same weight, or more. Batteries or solar power are orders of magnitude less powerful, and simply can't provide the power needed for a full-size helicopter, although they can power models for a few minutes. Clean, cheap power, without the need for fossil fuels is the holy grail of aviation, automotive, and other engineering, but they're not close to being available. There has been relatively little research on alternative energy sources done in the past few years, because the government refuses to fund it.

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These guys claim to have a process for making a biofuel drop-in replacement for 100LL. They claim to be 18 months from full-scale production. Of course, 18 months sounds a lot like "any time soon now"... but this is one that'd be really nice, if true.
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Do you think full-size electric or fuel cell helicopters are a possibility?

 

In the view of the exploding oil price I am confident that within the next 50 years the transition to all electric aircrafts should be done. What we need are fuel cells with high power to weight ratio and gearless electric motors that can convert the DC currents from the fuel-cells directly into torque.

 

I have invented a homopolar DC motor especially for contrarotating rotors. The estimated power-to-weight-ratio is 0.6 kW/kg for the superconducting version. You can view my design on the frontpage of my homepage

 

 

Best regards

 

Friedbert

 

_____________________________________

 

Imagination is more important than knowledge (Albert Einstein)

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I think by the time they figure out the weight to power ratio good enough for rotary flight, we'll be flying on impulse engines and warp drive. The helo will be the thing of the past.

 

Yes...but then it has to be tested and certified for and by the FAA. And by the time that happens a whole OTHER drive system more advanced than impulse and warp will be invented. :rolleyes:

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