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So, did/does the vehicle in the desert start with a push (from a force other than the wind) or did it really get started moving by the wind pushing it? Edit: F
by jrs235 5y ago
So, did/does the vehicle in the desert start with a push (from a force other than the wind) or did it really get started moving by the wind pushing it?
Edit: FYI in the video he does sort of cover his claim even if it got started by a non wind force by stating the vehicle can maintain a speed faster than the wind pushing it. But I'm still curious, was a non wind force needed in the desert to get it started?
- Retric 5y agoNo, it’s light enough for the wind to start pushing it.
- jrs235 5y agoEven with 100+ pounds (50+ kg)?
- Retric 5y agoYes, at the extreme end you can find videos of 3,000+ lb cars flipped by the wind. It looks quite aerodynamic, but by comparison I can start pushing a 3,000lb car on flat level ground. So this thing probably needs less than 10 pounds of force to start moving.
- mumblemumble 5y agoAny wind that's strong enough to overcome static friction would do the trick, and I can't see why 10mph wouldn't be enough. The small models that you can build at home (sorry, can't find the plans anymore; this was 10 years ago now) do not require a push to get started.
- jrs235 5y agoUnderstandable that it doesn't take much wind for a vehicle well under a pound. But what about one that weighs well over 100 pounds?
- mumblemumble 5y agoThe 100 pound vehicle also has a much larger cross section to the wind. And its propeller is further off the ground, so it's getting cleaner wind than the little model version. I can get a boat that weighs more and has less sail area going on less wind than that. And that thing has to be dragged through the water on top of everything else.
- amluto 5y agoIn the water, there is no static friction and no velocity-independent friction. If you push a floating boat, it moves.
- deleted 5y ago[deleted]
- mumblemumble 5y agoFair point. Though, I would guess that Blackbird's internal mechanisms are well-enough engineered that it has very, very little static friction where it counts.
- wongarsu 5y agoIn the veratasium video [1] you can see it starting just from the wind (first attempt is around 5:20). It works just fine because as you scale up the vehicle you scale up the propeller, so there's plenty of surface for the wind to push against. 1: https://www.youtube.com/watch?v=jyQwgBAaBag https://www.youtube.com/watch?v=jyQwgBAaBag
- dharmab 5y agoMy motorcycle with me on it can weight 700-800 pounds and has a much smaller cross sectional area than blackbird. And yet it still gets pushed around sometimes by crosswinds .
- IntrepidWorm 5y agoIf I understand what you're saying though, you would be in motion on the bike as the crosswind pushes against you- it takes a lot less force to shift your heading while moving forwards than if you were being blown sideways while stationary. Unless I'm misinterpreting your statement- perhaps you have a hobby of riding in hurricanes, which would be rad. :)
- raisedbyninjas 5y agoThe fan blades are an airfoil, which have a minimum speed to create the lifting effect.
- deleted 5y ago[deleted]
- mumblemumble 5y agoLift isn't really a part of how this gets started. Regular old pushing works on airfoils, too.