Ducted Fan Proyect

Es un proyecto basado en los motores del Skycar de Moller.
Me comentaron que si el motor delantero gira a menor velocidad que el de atrás puedo obtener mayor empuje que usando solamente un motor.
Comentarios?

Saludos!!

This proyect is based on the Moller´s Skycar.
Somepeople say me what the front motor must be rotate more slowly than the rear motor for obtain more push power.
That is?
Comment?
Cheers n thanks!!

Category:

Autos & Vehicles

Tags:

• ducted
• fan
• proyect
• aeromodelism
• electric
• motor

[bnewman227]

sorry to rant... the tiny 50mm 200Watt electric fans push a plane as fast as the huge 5kW IC fans but they will only fly a 500g craft as opposed to the 5kW fan's 10000g. Thats the practical difference. The bigger the swept area- the more efficiently the power is transformed to thrust/efflux.

checkout the turbax fans, wemotec, schuebeler etc.

you can get 80% efficiency or so with a cheap unit (about $25-$50), but to get an extra 5% or so it's real fine manufacturing with fans $300+

[blastodermus]

ho man!! this comments is gold for me!

i come to investigate about this.

next week i come to publish some anims for this project and hope your comments!!!

Thanks alot again!!

[bnewman227]

you could get rid of the flow straighteners by going for a counter rotating prop- 2 fans, different pitch. But again itd be really lossy at all but a small range of conditions.

[blastodermus]

a single ventilator with good power is better that two working against rotation. I will look for motors with good power and I will test.

Thanks for the commentary!

(u r the man!)

[bnewman227]

if this is for air then it's fundamentally flawed as the work done by the second fan is virtually none, unless you can get a variable pitch and variable rpm rear fan youll be fighting massive losses with whatever small gains you get. its more like an airbrake at all speeds except for a very small range.

[blastodermus]

mmm... interesting... so, read my new info about this proyect n tell me what you think

Thanks for comment!!!

[Scorpion85629]

Just put a motor into a gas turbine engine's combustion section: removing all fuel burning components and put in place a high RPM motor with an elongated shaft to enable an inline alternator for charging and system maintenance purposes.

[onlyacog]

my dad built the engines for that

[bnewman227]

efflux. by going for high blade numbers you can absorb lots of power and generate lots of thrust, but low efflux. The opposite is also true. Thats why most good fans are a balanced mix of efflux and thrust for general application. The most efficient is a 2 bladed shrouded propeller- the more blades the more losses. BUT, with more blades you can turn more power into performance. Checkout the Dynamax fan (old school IC type) versus some of the high rpm small electric ones...continued

[bnewman227]

hey man, no problems. most people on YT would take my comments as an insult. I did initially expect that actually. But I am surprised. If you really want to design a good fan diameter is king, and number of blades ensures the most power absorption. Also, keeping rpm relatively low means that you dont need to worry about reynolds numbers and cavitation.

you might want to look at a side by side arrangement if height is an issue..making the most of swept area.

the tradeoff is...continued..

[bnewman227]

yeah, its not really possible mate. its not that the fans need to spin at different speeds, its that the pitch needs to be aligned properly...otherwise its doing more harm than good. you can get better performance with a single fan that is a mix of pitch and blades to get a blend of thrust and efflux, or you use a variable pitched fan....the thing with the variable pitch is that not only the pitch has to change, but also the blade geometry.

basically its too hard to be practical.