Prop vs Turbine Race

Yet another video to address claims from forum contributors that a cart driven by a turbine would beat a cart driven by a propeller. In the end we reverse the direction of the transmission on the turbine cart to return it to its former life as a DDWFTTW prop-cart. We mount a dowel to the cart frame, and race that cart against the wind. Toward the end of the course you can see the tell-tales blowing aft, indicating the cart is going faster than the wind. But we don't expect to convince anyone with this poorly shot video. We've learned better.

Category:

Science & Technology

Tags:

• DDWFTTW
• DWFTTW
• Downwind
• prop
• propeller
• turbine

[SirDave144]

As a point, given prop blast (blowing a telltale backwards), might it not make sense to put a telltale on the FRONT of the cart?

[spork33]

We think it makes more sense to keep the telltale well off to the side so it's not in the path of the prop at all.

[iamserow225]

Since your full-size vehicle has a variable-pitch prop, would it possible to in effect make it a 'turbine-mode' vehicle from v=0 to v=Vwind by making the prop pitch angle negative, and then transitioning to the existing positive prop angle 'prop-mode' vehicle to accelerate from there on?

Also, I was wondering if there was a way to calculate the optimum prop angle at any given point in the run (based on apparent wind?), or set up some sort of mechanical feedback system to do it automatically?

[sixmagpies]

You go guys....this is fabulous stuff. Yes, a bit better recording would be great...but still good stuff.