Hi all,



this question is not 100% related to RC flight, but I summoned the courage to ask anyhow, in hope that someone would be willing to share their knowledge of ducted fan systems.



I currently have a project, where i need to use a very low power fan (20 watts) and use that given fan assembly to make a vehicle go as fast as possible over 10m (whilst still sustaining some tractive effort).



I have thought of two concepts for this, one being the obvious ducted fan out the back of the vehicle as a 'jet'-of sorts and the other being a turbine which rotates on the ejected air from the fan.



Obviously because of the simplicity of my first idea, I favour that-however i am very much unaware of whether or not this will be powerful enough to run my vehicle. Will i get more power by using a turbine/gears?



If i was to use a 'jet' what would be the down side?



Again i do apologise for what may be a very beginner question in regards to fans/ducts.



Thanks in advance



Ani

I can see a way to "cheat" on this if the fan unit has to stay attached to the electric motor

The fan would have very low thrust so any vehicle would need to be as light as possible to get much acceleration and the fan itself won't be very efficient anyway. Using the fan to drive a turbine (presumably connected to the wheels?) would be even less efficient.

What you'd want to do is make the most of whatever power the motor can produce. First off, no matter how you do it, the vehicle has to be as light as possible so use balsa anywhere you can. Aerodynamics won't have any affect at the speeds it won't be capable of . Then I'd blank off the front, back and ends of the fan with light cardboard or whatever so the fan is totally enclosed and not have any air drag. Attach a small pulley to the fan shaft and another pulley on one of the wheel axles and use a rubber band to drive it. Play with pulley sizes until you get the best performance (the rubber band will allow for any differences in sizes).

I'd build a Hovercraft