Rotor: 2 blade vs 4 blade

[THI]

I was thinking, and no it wasn't after a couple of drinks The development of flying cars is becoming more and more common. So why can't a flying car with a rotor system be on the table? For one the transport of the rotor system. Its just too long. So why not use a shorter 4 blade rotor.

The most common rotor used is the 8.4m (27ft) rotor.

Will a 4 blade rotor (5 meter) be so much more difficult to implement? What a bout RRPM? What RRPM's are we talking about?

A foldable rotor system has already been implemented for helicopters, why not gyros?

You know...just thinking

[MPL Pilot]

I understand there are serious stresses on the Rotor head because of the movement from the 2 sets of rotors.

Seems RotorTec has a system that work.

[Learjet]

Thi, I thinks its probably a case of cost versus benefit.
4 bladed rotor system necessitates a more complex rotor head, additional weight, requires more hangar space and is ultimately a more expensive machine to manufacture - without necessarily offering a vastly superior flight envelope for the price tag.

There are also resonance issues which came into play with a dual rotor system - better insights and explanations here http://www.rotaryforum.com/forum/showth ... aded+rotor

Dave

[okflyer]

Rotortec had some really impressive results with the four blade rotors.
See Video
http://www.youtube.com/watch?v=iDbRR9mLLHk
As much as I know, they still plan to deliver the CD2 with the 4 Rotors as the standard configuration. But after changing from aluminum to carbon (due to the different resonance characteristics of the two materials) they are now in the process of redesigning/ adjusting the rotor head to deal with carbon. With the aluminum blades the CD2 delivered impressive climbing performance and smoothness. As the blades can be folded, even less hangar space is needed (the blades are shorter as well).
The owners of the already delivered CD2 have the choice to change to 4 blades once the certification have been granted. Hopefully I will fly 4 blade configurations soon (I have already flown the 2 blade carbon blades). Then I will be able to give feedback.