Ballpark Length for Shrouded Propeller
Ballpark Length for Shrouded Propeller
(OP)
Hi, I'm interested in exploring a shrouded propeller for a quad rotor helicopter. Before I get to far into the process I'm wondering if there is a general rule for duct length versus propeller diameter. In other words, if I have a 10 in propeller how far (approx) past the prop should the duct go to help eliminate tip vortices and how far above the prop should the duct go to realize thrust gains due to the pressure drop across the inlet.
Thanks for your help.
Thanks for your help.





RE: Ballpark Length for Shrouded Propeller
RE: Ballpark Length for Shrouded Propeller
BUT that may explain the poor FoM they get
Cheers
Greg Locock
Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips.
RE: Ballpark Length for Shrouded Propeller
wouldn't that create a very large surface
ie, lots of drag ?
RE: Ballpark Length for Shrouded Propeller
If the rotors blow through a structure that's already present for other reasons, as in fenestron tail rotors, then the structure specifically associated with the duct is not such a big problem.
Mike Halloran
Pembroke Pines, FL, USA
RE: Ballpark Length for Shrouded Propeller
RE: Ballpark Length for Shrouded Propeller
Even with four of them this is not going to be lifting a person and range/duration or even forward speed are not an issue.
I am curious to see how the RC servos will be connected to control it.
Also heard Moller is getting close to "flying" their similar machine.
RE: Ballpark Length for Shrouded Propeller
RE: Ballpark Length for Shrouded Propeller
Mike Halloran
Pembroke Pines, FL, USA
RE: Ballpark Length for Shrouded Propeller
By the way, thanks for the help so far. As an aside, I also contacted Mr. Marc de Piolenc who has written a book on the topic. He said that his simplified model using a duct length of one prop diameter.