Rc Flying Enthusiast....

[bowers baldwin]

No, propellors cannot autorotate in the helicopter sense! Multiple propellors on these quadcopters provide lift and control by differential thrust outputs. These aircraft are effectively "hanging on the prop" like an aeroplane going vertically then slowing to a stop. Helicopter rotors work differently, with constant rotor rpm and cyclic and collective pitch changes. Having a freewheel device built into the transmission system is only part of the equation. Don't forget that the main rotors of a helicopter provide lift as well as thrust. Once a helicopter's engine stops providing power, it is the airflow from below due to the rate of descent that provides the rotor thrust. In simple terms, the airflow through the rotors comes from below, rather than from above, as it is in the powered state. It's actually the inner part of the rotor diameter (nearest the hub) that provides the autorotative force which drives the rotors round/forwards in relation to the rotor mast. Unless a proper collective pitch change mechanism is present, "propellors" will rapidly slow down and probably stop. Once they no longer provide thrust, there is no lift and no control of the aircraft.

Good answer, Ive never had to dead stick any of my helos, (they are all electric) and if I did have a main motor fail I am sure I would crash it, I haven't even practiced it, love to try it in a simulator though.

 

[Cache Man]

parachute?...

Ha! I think you are being funny and know this but... Which way or direction does the helicopter go when "falling" from engine failure? The parachute slows that fall. What is that large turning thingy above the helicopter? Can you say sushi?

At one time they were talking about having main rotor blades that jettison and so ejections seats could be used. This hasn't been utilized for several reasons.

 

[bowers baldwin]

Ha! I think you are being funny and know this but... Which way or direction does the helicopter go when "falling" from engine failure? The parachute slows that fall. What is that large turning thingy above the helicopter? Can you say sushi?

At one time they were talking about having main rotor blades that jettison and so ejections seats could be used. This hasn't been utilized for several reasons.

Just undue the Jesus nut first, then deploy the chute.

 

[Cache Man]

No, propellors cannot autorotate in the helicopter sense! Multiple propellors on these quadcopters provide lift and control by differential thrust outputs. These aircraft are effectively "hanging on the prop" like an aeroplane going vertically then slowing to a stop. Helicopter rotors work differently, with constant rotor rpm and cyclic and collective pitch changes. Having a freewheel device built into the transmission system is only part of the equation. Don't forget that the main rotors of a helicopter provide lift as well as thrust. Once a helicopter's engine stops providing power, it is the airflow from below due to the rate of descent that provides the rotor thrust. In simple terms, the airflow through the rotors comes from below, rather than from above, as it is in the powered state. It's actually the inner part of the rotor diameter (nearest the hub) that provides the autorotative force which drives the rotors round/forwards in relation to the rotor mast. Unless a proper collective pitch change mechanism is present, "propellors" will rapidly slow down and probably stop. Once they no longer provide thrust, there is no lift and no control of the aircraft.

In auto rotation the pitch of the main rotors are put in a negative pitch (negative collective)(the collective and throttle looks like an emergency brake handle on the left side of the pilot - throttle is usually a twist knob on the end of the collective stick) rather than a positive as in flight. This is called wind milling or autorotation. What occurs is the main rotors essentially become glider wings. All parts of the blade create lift. The blades have an airfoil shape which creates this lift. So the pilot is compensating altitude for air speed or rather lift. The decent rate in an autorotation mode is very fast with little time to make decisions other than looking for a spot to gracefully land (crash). It is all in the timing that will determine if it is a crash or hard landing. The point is to obtain maintain the main rotor speed and just before impact switch to a positive pitch (increased lift - pulling collective) to slow or stop the decent. By doing so you loose rotor speed/lift. And if you are not very close to the ground, the helicopter will fall out of the air and crash. How bad of a crash depends on how high above the ground you are when you loose lift or if you fail to flair soon enough and hit the ground hard. It is all in timing.

When practicing auto rotations you keep your engine hot and flair before touching the ground as if the ground is higher up. Engaging the transmission. Eventually you are allowed to touch down. Many helis have been damaged by doing this. It is only used as a last effort.

 

[goofyone]

In auto rotation the pitch of the main rotors are put in a negative pitch rather than a positive as in flight. This is called wind milling or autorotation. What occurs is the main rotors essentially become glider wings. All parts of the blade create lift. The blades have an airfoil shape which creates this lift. So the pilot is compensating altitude for air speed or rather lift. The decent rate in an autorotation mode is very fast with little time to make decisions other than looking for a spot to gracefully land (crash). It is all in the timing that will determine if it is a crash or hard landing. The point is to obtain maintain the main rotor speed and just before impact switch to a positive pitch (increased lift) to slow or stop the decent. By doing so you loose rotor speed/lift. And if you are not very close to the ground, the helicopter will fall out of the air and crash. How bad of a crash depends on how high above the ground you are when you loose lift or if you fail to flair soon enough and hit the ground hard. It is all in timing.

When practicing auto rotations you keep your engine hot and flair before touching the ground as if the ground is higher up. Eventually you are allowed to touch down. Many helis have been damaged by doing this. It is only used as a last effort.

You are newer here, so you likely would not know this, however I do believe wheaters is well aware of this as he happens to be an active professional helicopter pilot.

I do thank you for the general information, as while we do have more pilots here, the majority of us are not.

 

[CompTrex]

[snip] he happens to be an active professional helicopter pilot.

But I'm not! Keep it coming. This is fascinating!

 

[bowers baldwin]

Ok favorite non-fixed wing birds:

Bell 47
Sikorsky H-19
Kamov Ka-26

funny, I like these but I don't trust piston powered helicopters..

 

[goofyone]

But I'm not! Keep it coming. This is fascinating!

I was getting around to that.

 

[bowers baldwin]

Man carrying? Speaking as someone sitting in a helicopter every working day......what happens in the event of engine failure?

I think they said it could lose 3 and still fly, nice to have multi-engines.

 

[Cache Man]

You are newer here, so you likely would not know this, however I do believe wheaters is well aware of this as he happens to be an active professional helicopter pilot.

I do thank you for the general information, as while we do have more pilots here, the majority of us are not.

Is Wheaters one of those crazy Hughes 500 pilots dangling a saw below to cut trees by power lines?

Or this??