When helicopters run out of fuel...

[LeperousDust]

Right here your totally random question for the day:

When a helicopter runs out of fuel, does it:
a) drop like a rock
b) descend slowishly

Answers on a postcard, and can i have credible sources backing up which ever answer you think is correct.

I'm having a little argument with someone, and would just like someone to back me up, and some proof.

 

[Andr3w]

if the blades stop spinning it will drop like a rock

 

[OzZie]

It would decent "slowishly" and spin around i imagine.

 

[sniffy]

Is the chopper moving forward or is it hovering?

 

[DaveyD]

Well it's not going to have any fuel to spin the rotor blades, therefore they wont spin, and it'll just fall. I guess the blades would slow down pretty quickly once fuel has gone.

The rotor blades are the only thing that keeps the helicopter in the air, and that can only be done by creating a downforce from the spinning rotor blades.

 

[Jotun]

B No sources though, it cropped up in a discussion during phyiscs a few years ago.

 

[iCraig]

The blades would slow gradually, as their momentum would keep them spinning.

Probably giving the pilot enough control to land safely. But if they tried to stay in the air with a stalled engine, the helicopter would begin to fall..fast.

 

[Overload]

It would decent "slowishly" and spin around i imagine.

If you had a experienced pilot. Been on a gazelle and they turned of the engines - to simulate engine failure - and just span around towards the ground. We certainly did not drop like a rock .

 

[Akira]

If you disengage the rotors from the engine before it stops, a helicopter can perform what's known as 'autorotation' which will allow it to descend safely and land.

http://www.copters.com/pilot/autorotation.html

 

[Replicant]

Is it true that there's a sweet spot at the rotor blades that if you shoot at it, it will drop

 

[Mr_L]

I don't have anything to back it up and it might be complete balls, but I remember seeing somewhere that if a helicopter is loseing power the pilot takes it down quickly. The force of the air coming up against the blades then makes them spin round to give some lift and lesson the impact. It's still effectively falling with style, though.

Edit: Looks like Akira might have posted what I'm talking about.

 

[Jotun]

Is it true that there's a sweet spot at the rotor blades that if you shoot at it, it will drop

Depends what you shhot it with

 

[spirit]

Is the chopper moving forward or is it hovering?

wouldn't really matter would it?
imo:
It would drop, but it may take some time for the blades to actually stop spinning (inertia and such), the higher it up it would be the longer it would take for blades to stop spinning (air is less thin -> less friction) , eventually it'd fall until it reaches terminal velocity -- thats what i think

'cause unlike a plane allthe thrust is done from the blades so if they stop u fall -- i think. unless its like airwolf and he just turbos instead

 

[sniffy]

wouldn't really matter would it?
imo:
It would drop, but it may take some time for the blades to actually stop spinning (inertia and such), the higher it up it would be the longer it would take for blades to stop spinning (air is less thin -> less friction) , eventually it'd fall until it reaches terminal velocity -- thats what i think

'cause unlike a plane allthe thrust is done from the blades so if they stop u fall -- i think. unless its like airwolf and he just turbos instead

Yeah thinking about it, it probably wouldn't.

I would opt for B.

 

[DaveyD]

If you disengage the rotors from the engine before it stops, a helicopter can perform what's known as 'autorotation' which will allow it to descend safely and land.

http://www.copters.com/pilot/autorotation.html

Going from that, as long as the blades disengage from the engine, then it would not fall from the sky, and you'll have a short amount of time for them to keep spinning. I guess when connected to the engine, they'll slow down a hell of a lot quicker as they'll have the gears and dead engine to help slow them down along with them losing their momentum.

 

[NathanE]

Autorotation requires that 1) the chopper is moving at substantial speed, and 2) that it is at a fairly high altitude. Otherwise, yes its a 'falls like a stone' moment for everyone on board.

Technically the pilot has as long as he likes to get the chopper down. It is essentially gliding down... the movement of the air over the rotors keeps them spinning.

This is why you rarely see a chopper staying still/hovering. The pilots don't like doing it for safety reasons. They know that if anything went wrong they'd be dead in a few seconds... :/

 

[panthro]

If you disengage the rotors from the engine before it stops, a helicopter can perform what's known as 'autorotation' which will allow it to descend safely and land.

http://www.copters.com/pilot/autorotation.html

Good man, was just going to say the same thing

 

[The_KiD]

Right here your totally random question for the day:

When a helicopter runs out of fuel, does it:
a) drop like a rock
b) descend slowishly

Answers on a postcard, and can i have credible sources backing up which ever answer you think is correct.

I'm having a little argument with someone, and would just like someone to back me up, and some proof.

Trick Question, the helicopter isnt flying at the time !

 

[Le_Petit_Lapin]

I hear they can glide, given the right angle of descent, it keeps the blades going just enough so that it doesnt:

(a) Drop like a stone.
(b) Stall, then drop like a stone.

Cant remember the source though. It was years ago at any rate and possibly on T.V. Still, even gliding, a helicopter of any description does not strike me as a suitable object for making a crash landing in. I doubt the "landing" would be entirely pleasant, even if you do "glide".

Edit: Bleh....you want proof...

 

[Stiff_Cookie]

They will desend but not fall. I wouldnt say its a slow desent but its not falling like a rick either.

Source: Dad is a flight engineer on the MH-53J Pavelow and has been for about 20 years.