Designing an Air-Powered Car: Seeking Advice

[kinroh]

hey guys!

i need your oppinion and advice/suggestions on somthing.

My group for university has to design and build a small model car within the dimensions (300x300x700) mm
that runs on air, using a dustbuster motor. i don't have the model name but we can assume the motor we're dealing with is quite weak.
Now, there can't be any mechanical connection with the motor and the axle of the car- since we need to harness airflow.
weight plays a crucial issue when designing such vehicles..air power is a relatively weak force. We can't use any explosives or dangerous materials.


any words of advice would be great!

 

[Danger]

Are you restricted to also using the fan that comes with that motor? In any event, I'd be looking at a ducted fan to start with.

 

[russ_watters]

I wouldn't think a dustbuster fan would be all that well suited for propulsion (high pressure, low flow). If you could get (or construct) a fan curve, that would be helpful, but you'll likely find that your pressure drop will be virtually nonexistant regardless of your duct size, so your airflow will be whatever the max that fan can produce is.

The reason airplanes and air boats use propellers is they are better at producing higher airflow and no static pressure than centrifugal fans, which are better at producing pressure, but not as good at producing airflow.

 

[kinroh]

yeh, we have to use the dustbuster motor, which is designed for optimal sucking.
How do you think we should set up a ducted fan?

 

[Danger]

I don't have a Dustbuster right handy to disassemble, so I'm not sure what the internals are like. Maybe start by just reversing the polarity of the motor and see if you can feel any significant airflow coming out of the suction nozzle.
There's also the possibility of over-driving the motor for extra power (ie: higher than standard voltage), but I'd consult one of our electrical guys like Berkeman before trying that.

 

[kinroh]

yeh makes sense. I am just wondering, if the airflow we can work with is enough to actually rotate a duct fan, or propeller that is connected to an axle to move the model foward.