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For those that hate the way news articles are written I found the Wikipedia article a much clearer read https://en.m.wikipedia.org/wiki/Blackbird_(wind-powered_vehi...
Like the professor in TFA I am also confused: how can the ground be imparting power to the propeller while moving downwind?
I first assumed it was the other way around with wind->propeller->wheels, which it is not.
Odd that the professor was so keen on betting in that case.
That's a terrible explanation - no wonder people doubt the system would work!
Turns out, it has been done: https://www.youtube.com/watch?v=q2il8Fagbyk
For those that hate the way news articles are written I found the Wikipedia article a much clearer read https://en.m.wikipedia.org/wiki/Blackbird_(wind-powered_vehi...
Like the professor in TFA I am also confused: how can the ground be imparting power to the propeller while moving downwind?
It's an overdrive—the wind pushes the vehicle faster than the wind itself, but the vehicle gets less net propulsion force when you sum up the tractive force and the wind force.
> The secret to Blackbird, Cavallaro explained, is that once the wind gets the vehicle going, its wheels start to turn the propeller blades — they're connected to the blades by a chain. As the vehicle speeds up, its wheels turn the propeller faster and faster. The propeller blades, in turn, act as a fan, pushing more air behind the land yacht and thrusting it forward. That's a terrible explanation - no wonder people…
> The secret to Blackbird, Cavallaro explained, is that once the wind gets the vehicle going, its wheels start to turn the propeller blades — they're connected to the blades by a chain. As the vehicle speeds up, its wheels turn the propeller faster and faster. The propeller blades, in turn, act as a fan, pushing more air behind the land yacht and thrusting it forward. That's a terrible explanation - no wonder people…
This is slightly off topic but I have been using this trick lately to try to determine which part of a news article is likely to be BS: read the article in the movie announcer voice (you know the one: “in a world gone mad, one man…”). Whatever headlines or parts of the article sound boring are likely to be legit and whatever parts sound like they would fit in an action movie are likely overblown, underreseaeched, irr…
In this case, your BS detector is giving you a false result: https://youtu.be/yCsgoLc_fzI?t=275
I would still argue that BN and NdT are only the biggest names in pop science (as in people who wear “I <3 science” t shirts) and not in science as in academia. But that’s cool that they did weigh in on this subject.
> The secret to Blackbird, Cavallaro explained, is that once the wind gets the vehicle going, its wheels start to turn the propeller blades — they're connected to the blades by a chain. As the vehicle speeds up, its wheels turn the propeller faster and faster. The propeller blades, in turn, act as a fan, pushing more air behind the land yacht and thrusting it forward. That's a terrible explanation - no wonder people…
Yeah, my first inclination is that since the wind is turning the propeller and the propeller is turning the wheels via a gear system, the speed of the vehicle will be determined by the propeller speed, the gear ratio, and the tire diameter (ignoring friction and air resistance for a moment). The gear ratio is the critical component. It's not like the propeller is a simple sail. I could be completely missing something…
If you watch the videos when the thing is first getting going, it is slow enough to see that the propeller is actually spinning in the opposite direction it would be if it was acting as a windmill.