ThinAirDesigns
Joined 16 years ago
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Comment · 16 years ago
Comment · 16 years ago
It is likely that the team from San Jose State University will use this vehicle to answer that very question during the next academic year, but it will involve a bit more work than just transmission changes.
While it is true that with only ratio changes the vehicle can be made to drive directly upwind, it would not be all that efficient as the airfoils currently on the vehicle are propeller blades and not turbine blades. A set of properly cambered blades will need to be fabricated and installed and then the test could be done.
One thing to remember is that when traveling upwind, the apparent wind over the chassis will be higher for any given multiple of wind speed. Upwind at 1x WS gives the same apparent wind as going 3x downwind.
The current 'record' for directly upwind is ~64% of wind speed.
http://www.gizmag.com/the-first-race-for-wind-powered-vehicl...
Comment · 16 years ago
Me: "it can't be using the stored energy in the propeller"
You: "Note that I didn't say it was. Sorry to get you off-script."
Wow -- you make a clear claim and then two posts later are denying you even said it. I'll refresh your memory: This is you claiming that the vehicle uses stored energy: "It is admittedly using stored energy - the propellers are spun by the wheels,"
You: "You rushed in to try to get a layman to give explicit parameters for disproving it."
Nope -- I merely asked what would convince you -- big difference.
Comment · 16 years ago
Actually naz, that is one of the key and common misconceptions of this vehicle -- the propeller IS producing thrust.
Contrary to popular believe, the spinning rotor is not a turbine (as you describe), but rather a garden variety prop which is driven by the wheels.
Comment · 16 years ago
@Semiapies:
>It is admittedly using stored energy - the propellers are spun by the wheels, which are spinning due to the vehicle's forward motion.
I'm sorry, but by that logic your car is also "admittedly using stored energy" to accelerate (as the wheels and other parts are turning due to the vehicles forward motion) and we know this isn't the case. Just because there exists stored energy in a system, doesn't mean that this stored energy is being used and in fact, as the vehicle accelerates, more energy is stored rather than energy being used.
In the case of this vehicle, it can't be using the stored energy in the propeller without it turning progressively slower and the videos show the propeller simply continuing to spin faster as the vehicle accelerates.
The gearing between the prop and the wheels is fixed ... there's no way to slow the prop down and speed the wheels up -- that would require a variable ratio between the two.
Semiapies: <<Trying to put skeptics on the defensive and trying to force them to disprove the remarkable claim put forth is a classic shtick.
I don't recall attempting to force you to disprove anything. I simply asked period of time would convince you. You can call it "shtick" if you like -- I call it attempting to learn your position.
Comment · 16 years ago
@Semiapies:
A: if the vehicle can accelerate under the power of the wind to several multiples of the windspeed, what would suddenly make it slow down? Are you suspecting stored energy is being used somehow?
B: How long of a run would convince you?
Comment · 16 years ago
There is no stored energy involved in the acceleration -- it is all powered by slowing the air down relative to the surface(as all wind powered craft do).
Moving on.