Ducted fan, contra-rotating or stators?
Ducted fan, contra-rotating or stators?
(OP)
I was wondering what is likely to be most efficient in a ducted fan. The design of the duct is long, approx 4x the diameter. This is to be used to create thrust, not as a compressor
The option of placing 2 to 4 contra rotating fans/props or...
placing 2 to 3 fan/props rotating the same direction and using stators in between. Each fan/prop would have a different pitch and increasing number of blades as seen on a turbine compressor.
Any info will be appriciated.
The option of placing 2 to 4 contra rotating fans/props or...
placing 2 to 3 fan/props rotating the same direction and using stators in between. Each fan/prop would have a different pitch and increasing number of blades as seen on a turbine compressor.
Any info will be appriciated.





RE: Ducted fan, contra-rotating or stators?
stators have the advantage of providing a really usefull support to the cowling. i guess you could possibly make the stators variable pitch, but i suspect the improved efficiency will be offset by the increased complexity and weight.
RE: Ducted fan, contra-rotating or stators?
Mike Halloran
Pembroke Pines, FL, USA
RE: Ducted fan, contra-rotating or stators?
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: Ducted fan, contra-rotating or stators?
On a boat, weight would be less important.
Mike Halloran
Pembroke Pines, FL, USA
RE: Ducted fan, contra-rotating or stators?
RE: Ducted fan, contra-rotating or stators?
RE: Ducted fan, contra-rotating or stators?
It's not homework, this?
RE: Ducted fan, contra-rotating or stators?
RE: Ducted fan, contra-rotating or stators?
By design, the overall geometry limits the diameter of the duct. The length of the duct runs nearly the entire length of the fuselage (like seen in a F-86 Sabre, Mig-17 & Mig-21).
It is powered by electric motor(s). I've upgraded the power pack and motor(s) providing a substantial increase in power/weight ratio and have plenty of wiggle room as far as gross weight is concerned.
Contra-Rotating is simple with these electric motors and will weigh no more than the alternative setup of having them rotate in the same direction.
The power-pack will provide more endurance than I need and the motors can produce more power than a single fan/prop can absorb.
I was looking for advice on which would provide me with the most thrust for the given power.
Concerning the comments about the stators, If I am going to put several fan/props inline, all rotating the same direction there will have to be stators to redirect the airflow off of the leading fan/props blades to provide an optimal angle of attack for the next fan/prop.
When it comes to ducted fans, I'm lost. This is just something I took up in my spare time for fun. As far as calculations go, it's just a shot in the dark. I was just wondering what your opinions were on the best way to go as far as contra-rotating or single direction rotation with stators? I have the option to add multiple stages. I'm looking for recommendation on what will give me the best thrust/weight ratio.
Thanks,
CS
RE: Ducted fan, contra-rotating or stators?
my 2c, don't over-fuss the "ducted" part of the problem, just think of it as a prop with a geometry restriction. a key design point is accurately locating the center of the duct. this'll allow you to seal the tip of the baldes against the duct, i suspect that paddle tip blades should work well.
if weight isn't a problem, then i'd use more powered props. but since you're going to be creating shaft supports in the duct, why not make them stators ?
good luck with this !