Reply to: Electric Helicopter anyone?

[Wodewick]

Though it rarely gets out of ground effect.

I am no ornithologist but I am fairly certain that an albatros can and does flap its wings.... therefore it cannot be called fixed wing (although it/they do glide quite a lot)

[Wodewick]

Far too many "Jesus" bolts in helicopters.

After all, you've never seen a rotary winged bird, now have you?

Although I've never seen a fixed wing bird either come to that!

[Spacecadet]

Far too many "Jesus" bolts in helicopters.

After all, you've never seen a rotary winged bird, now have you?

not a bird, no

[Cliphead]

Put the thing in trim and it'll fly itself...

Exactly

[Churchill]

My past experience with helicopters wasn't a happy blending of man and machine (pardon the pun). I'll stick with fixed wing. Or maybe a gyrocopter.

Put the thing in trim and it'll fly itself...

[hyperD]

My past experience with helicopters wasn't a happy blending of man and machine (pardon the pun). I'll stick with fixed wing. Or maybe a gyrocopter.

Can't argue with that!

[Churchill]

Both change air density, so that's built in. But the formula is only for ball park purposes as material properties dominate at the end of the day.

Balls of steel!

http://youtu.be/ba-dln366-E

[TimberWolf]

Is that in or out of ground effect and what about pressure altitude?

Both change air density, so that's built in. But the formula is only for ball park purposes as material properties dominate at the end of the day.

[Churchill]

exactly, and weight.

The easiest efficiency gain would be to use a lighter pilot.

A rough estimate of the power needed to hover (ignoring material constraints) is:
(Mg)^(3/2) / (2 * r * sqrt(pi.air density), or roughly (8 *m ^(3/2))/r where r is the rotor length and m mass. So ignoring material considerations (weight of rotor doesn't scale linearly with length - bigger things get weaker), the longer the rotor the better.

There have been human powered helicopters too, but a wing is more efficient than rotors.

Is that in or out of ground effect and what about pressure altitude?

[TimberWolf]

All to do with energy density and releasing that energy in a controlled manner without things getting too hot.

exactly, and weight.

The easiest efficiency gain would be to use a lighter pilot.

A rough estimate of the power needed to hover (ignoring material constraints) is:
(Mg)^(3/2) / (2 * r * sqrt(pi.air density), or roughly (8 *m ^(3/2))/r where r is the rotor length and m mass. So ignoring material considerations (weight of rotor doesn't scale linearly with length - bigger things get weaker), the longer the rotor the better.

There have been human powered helicopters too, but a wing is more efficient than rotors.

[PAH]

Too likely to end up "in kebab form."

Yeah, the blades look a bit too close for comfort. I'm reminded of that scene in the original Dawn of the Dead whenever I see one of these designs.

I wonder why they don't enclose the blades in a protective box? For lift you only need air to move faster above the blade than below so don't need the whole atmosphere available to it.

Pressurise the box and you could go higher than any helicopter has before.

Have a closed box design and you could go into space.

Would also be useful for flying cars.

[this design lark is a piece of piss, where's my blank patent form...]

[Cliphead]

All to do with energy density and releasing that energy in a controlled manner without things getting too hot.

Nothing better than Avtur for that at the moment.

I for one wouldn't attempt to fly one.

Oi Cliphead, Helicraig, what about you?

My past experience with helicopters wasn't a happy blending of man and machine (pardon the pun). I'll stick with fixed wing. Or maybe a gyrocopter.

[doodab]

Too likely to end up "in kebab form."

And for that reason I am out. For now

Will battery evolution ever make this possible - sounds like they require a heck of a lot of power to keep them airborne.

Smaller model ones are almost all electric powered these days, which was more or less unthinkable 20 or 30 years ago. I suspect it's a matter of one more significant leap in energy density before it becomes mainstream, although I've no idea what that might be.

[Churchill]

Too likely to end up "in kebab form."

And for that reason I am out. For now

Will battery evolution ever make this possible - sounds like they require a heck of a lot of power to keep them airborne.

All to do with energy density and releasing that energy in a controlled manner without things getting too hot.

Nothing better than Avtur for that at the moment.

I for one wouldn't attempt to fly one.

Oi Cliphead, Helicraig, what about you?

[administrator]

Too likely to end up "in kebab form."

And for that reason I am out. For now

Will battery evolution ever make this possible - sounds like they require a heck of a lot of power to keep them airborne.