Rc Flying Enthusiast....

[CompTrex]

How heavy is your cat? [emoji2]

Bombs Away!
Right onto the dog!
Oh, I can see making a weekend of this!

 

[wheaters]

Same as any othe helo I suspect, gravity takes over.

Yes, but on a proper helicopter, you retain control in auto-rotation. Not in that contraption where everyone, including the pilot, instantly becomes a passenger.

 

[Cache Man]

I've flown RC aircraft and helicopters for several many years. It is fun. The quad-copters are a new craze because of their stability. They have quad or higher copters that have reversible pitch blades. It is a great hobby and the Elio is large enough to put a small to medium size airplane of heli.

Wheaters, Do you mean "proper" to imply expensive? If so I agree.

 

[wheaters]

I've flown RC aircraft and helicopters for several many years. It is fun. The quad-copters are a new craze because of their stability. They have quad or higher copters that have reversible pitch blades. It is a great hobby and the Elio is large enough to put a small to medium size airplane of heli.

Wheaters, Do you mean "proper" to imply expensive? If so I agree.

I mean one that is safe for human occupants!

 

[Cache Man]

I mean one that is safe for human occupants!

That depends on the maintenance and who is the pilot! Ha!

 

[wheaters]

That depends on the maintenance and who is the pilot! Ha!

Yes obviously they are factors too (same with any mode of transport) but my point is about the basic design. A helicopter that can't autorotate won't get certificated as a passenger carrying machine and I for one certainly wouldn't want to go flying in one.

 

[Keith Stone]

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

parachute?...

 

[goofyone]

Yes obviously they are factors too (same with any mode of transport) but my point is about the basic design. A helicopter that can't autorotate won't get certificated as a passenger carrying machine and I for one certainly wouldn't want to go flying in one.

Honest question as someone who only understands the basics of autorotation from reading and RC helicopters of various types. Why would you not be able to autorotate a quad-copter?

Dual propeller helicopter's can and do autorotate. Freewheel units and variable pitch propellers would of course be needed however those would be available on passenger carrying versions anyhow. The "dead man's curve" would of course have to be calculated for the aircraft however that varies by aircraft anyway.

Either way I am not sure if a quad-copter would be reasonable to build and use as a full sized aircraft for other reasons. They would have disadvantages in terms of added weight and mechanical complexity which of course means added costs to manufacturer, maintain, and in fuel consumption. Passenger carrying helicopters also rarely need the natural hover stability which makes the quad-copters popular in the RC world.

 

[wheaters]

Honest question as someone who only understands the basics of autorotation from reading and RC helicopters of various types. Why would you not be able to autorotate a quad-copter?

Dual propeller helicopter's can and do autorotate. Freewheel units and variable pitch propellers would of course be needed however those would be available on passenger carrying versions anyhow. The "dead man's curve" would of course have to be calculated for the aircraft however that varies by aircraft anyway.

Either way I am not sure if a quad-copter would be reasonable to build and use as a full sized aircraft for other reasons. They would have disadvantages in terms of added weight and mechanical complexity which of course means added costs to manufacturer, maintain, and in fuel consumption. Passenger carrying helicopters also rarely need the natural hover stability which makes the quad-copters popular in the RC world.

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.

 

[goofyone]

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.

I now understand where you are coming from now however we are talking about two different types of flying machine and I likely used some incorrect terminology which confused the issue. You are likely used to seeing the cheap little quad-copters which do indeed 'hang on a prop' however I am talking about more advanced quad-copters, known in RC circles as a '3D quadcopter', which do actually feature collective pitch control and as a result can even fly fully upside-down which, for the reasons you mentioned, is only possible with collective pitch change. These collective pitch control quad-copters are the type being used more often now as aerial filming platforms as they allow for greater stability and control.