Contra / Coaxial rotating Helicopters.

[prashantakerkar]

Helicopter rotor - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Helicopter_rotor)
Contra-rotating - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Contra-rotating)
Contra-rotating propellers - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Contra-rotating_propellers)
Coaxial rotors - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Coaxial_rotors)
Contra Rotating Spitfire XIX - YouTube
http://www.maxxprod.com/mpi/mpi-266.html‎
DSpace@MIT : Page not found (http://dspace.mit.edu/handle/1721.1/65309‎)
DSpace@MIT : Design and cavitation performance of contra-rotating propellers (http://dspace.mit.edu/handle/1721.1/61906)
Helicopter rotor - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Helicopter_rotor)


I want to discuss the advantages and disadvantages of implementing
Contra rotating helicopters design over the conventional main rotor system
in terms of manufacturing cost, efficiency, power etc


Thanks & Regards,
Prashant S Akerkar

[prashantakerkar]

The Design complexity will increase if more than two rotors in opposite directions are to be driven in odd and even configuration.

i.e.

3,5,7 etc Odd

4,6,8 etc Even

Increasing the Number of Rotors (3,4,5,6,7,8) can affect the
Helicopter speed ?

Isn't it ?

Thanks & Regards,
Prashant S Akerkar

[prashantakerkar]

Will 3,5,7 etc Odd configuration also work ?

OR

Only 2,4,6,8 etc Even Configuration work ?


Thanks & Regards,
Prashant S Akerkar

[Peter-RB]

Good morning PSA,

The Vid of the Spit was nice to watch so thank you for putting in for us old geezers to be able to look at what allowed us to carry on after the WW2,

The addition of the much larger engines in the Spit was to increase performance with the addition of both HP and torque, but that needed the Contra prop to be fitted to the Spit(and others) to allow the entire HP to be wrung out from engine so as to take advantage of that power increase and thus performance, the bigger engine would have needed a greater diametre single Prop, which would have been useless had not contras been fitted, one benefit is the contra prop was to reduce torque/turn movements when taking off and in high speed turns,.
The contra prop Helis seem to be able to harness this two Rotor system to greater advantage by making a very stable and powerful lift systems , athough the linkage is extremly complex( therfore costly to maintain), but also the helis dont seem to need to follow the same sort of build shapes that single rotor helis do

There now I have put my tiny knowlege onto this thread, perhaps some of the more professional people will give you more, and quiet possibly rip into my simple explanations, gleaned from years of books and stripping down Griff 58's to do silly things with them.
:ok:
Peter R-B
Lancashire UK