Comment by mNovak
1 day ago
Everyone's focusing on the cold gas thrusters, which of course is very cool, but not actually shocking that it technically could be done (economically is another question).
But can we talk about the just casually driving straight vertical or sticking to the ceiling? I didn't think that would be technically possible for a 1000kg+ car with probably at least 2" of ground clearance.
There's presumably very limited stores of compressed gas, so you might get one hop or a couple 0-60 boosts per charge. But with electric fans, suction is a feature with much longer duration (minutes?), so you could feasibly do the batman driving on the tunnel ceiling past traffic trick.
Saw pictures of its undercarriage on Twitter and it looks like it well have been a empty shell of a car
I saw the pictures but it wasn't clear to me that it was empty. I certainly saw comments saying it was. It looked like it was flat.
There is zero rebound when it lands, that's a bit weird. I replayed that part a couple of times, it doesn't look like there is any vertical velocity at all when it lands, which, given SpaceX's ability to do this with much heavier objects should be no surprise but it makes it look as if the vehicle has very little mass. If the tanks contain 250Kg of compressed air (which means it is pretty much liquid) and you toss that out in ~1 second or so then you'll be near the end of the depletion so if the vehicle would be launched just a little bit higher it would slam into the ground instead of gently landing. There isn't much reserve there.
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Link?
https://mcmurtry.com/upside-down-driving/
I wonder how the roadster got around any patents that McMurty might have.
It is possible that they might have licensed some of these patents. Either directly, or through a shell company to hide that it was for Tesla.
I wonder what patents they could have though? Not like they invented the concept.
That is very clearly not what is happening
You're right. The McMurty is an actual car with a driver in it.
What do you mean? It's the exact same concept
I can lift a 200 pound piece of glass with a tiny vacuum sucker. It's the atmosphere keeping that thing up there, and the 2" of ground clearance is what you see around the edge, we don't actually know what the distance is where the evacuation happens. For all you know it as a 3' x 7' plate underneath it that floats just above the surface.
I've done a lot of vacuum picking and it is surprising how large an object you can pick up with a tiny bit of surface.
Could you pick up, say, a manhole cover?
Mythbusters lifted a 2 ton car using a consumer grade vacuum cleaner. the math is this: the air pressure over 1 sq meter is about 10 tonnes, so if make a box with that area and reduce the pressure by 0.25 atm, you get a force of equivalent to 2.5 tonnes, enough to lift the car.
https://www.youtube.com/live/GbqKwPktCdo?xstg=CAMSBhUDze3xHw...
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Atmospheric pressure is around 14psi, at a rough guess a manhole cover is around 200lbs so you'd need just a little over 14sq in to make that work.
F1 has taught me: yes, and it will destroy your car.
Sure, why not?
The seal won't be perfect so you'll be running the pump more or less continuously. Apropos manhole covers: I wonder what would happen if this car would drive over one. Or was that your point?
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There is a racing car at a car museum, it was either BMW or Mercedes, which was mounted to the ceiling because it had a suction fan that would, in theory, let it do that.
Are you sure it wasn’t the Porsche 956?
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This is not how it works. It’s not sucking against the road, it’s pushing against it with thrusters at the top of the car.
No it’s not. It’s vacuum underneath.
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This is not actually the first time that this idea of using a fan to create downforce. It's been something that's been talked about and modeled for a long while and I think a few years ago, the McMurtury Speirling was released. That set the lap record at Laguna Seca among other achievements. The car is about a million dollars, and the fans are basically completely useless anywhere that's not a curated track (think stones, dust, wood, other FOD going through the fans).
The new roadster is obviously cool, but it looks like a practically useless vehicle for 99.9999% of the population. It's purely going to be a track princess -- with lots of extra weight for frankly pointless (but very cool) thrusters.
There was a Fan Car in F1 decades ago. Was good until it was banned!
At race speeds (say over ~150 mph), you don't even need a fan or any active mechanism. Just passive venturi channels on the underside can generate so much down force they are strictly limited in F1 because they can easily enable cars to sustain extremely unsafe speeds.
There are some McLaren street cars that use passive venturi channels which from their shape alone, generate more down force at high speeds than the car's weight. In theory, the car could drive upside down (if there was a Daytona-sized race track shaped like a ~30 ft diameter pipe).
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Yeah, it turns out that in very specific and controlled situations, using a fan to make downforce is great. It's also a very obvious thing to do in those situations and doesn't do much for you otherwise.
Imagine a normal car having to carry around the added weight of fans, COPVs, and the plumbing to make it work. And only being able to use those only if the track is clean and there are no other cars nearby.
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The Chaparral 2j is one of the most inventive and cool looking cars I've seen.
Not f1, Can-Am but yeah, I'm really surprised this isn't a more common approach to modern track cars. Obviously banned in most motorsport but I'm surprised with all of the one-offs these days that it's not more common.
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> but it looks like a practically useless vehicle for 99.9999% of the population
Well it's effectively useless for 100% of the population. It's just that 99.9999% cannot afford an expensive, useless car. Some people can, though.
It has pretty good filtration [1], and redundant fans. Some rocks aren't a problem. But, you can't be driving through LA.
[1] https://youtu.be/xkXvL8YCtIE?t=721
You can’t drive it anywhere that manhole covers might exist, lest you destroy the car and/or turn the manhole cover into a deadly projectile.
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I mean it’s a 250k car. Why is it supposed to be practical?
There are levels of impractical - this is so far beyond useless even compared to the most ostentatious luxury cars.
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I very much doubt the machine we saw flying was 1000kg+. It was either MUCH lighter, supported by cleverly hidden cables, or some other trickery. The dramatic lighting isn't just for visual effect, it makes it easier to hide the reality of the demonstration.
If there was a live audience anywhere near that stage they wouldn't have been able to use thrusters to fly something that actually weighs as much as a car.
What cable arrangement would you propose to move a car in that way? I think it would be easier to do with gas thrusters than with cables. They'd get tangled in each other.
I don't pretend to know the details of the show, but if it was actually doing what's implied I don't think the lighting would have been set up to hide so much.
To even entertain the possibility that they would use cables is ridiculous, to say the least.
I have more belief this trim will be made available commercially without significant changes (which is to say "not much belief") than belief you know enough about what was done to e.g. claim what the lighting is for that authoritatively.
To be fair: it wasn't really flying. More like it was "falling with style."
More like jumping. It was clearly able to lift off from the ground.
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It had 4700kg of downforce. It would’ve been quite a feat to make a vehicle (or prop, call it whatever you like) like that less than 1 tonne.
How do you know it had that much downforce?
They said it's under 700kg in an interview
That is not lot of batteries is it? So range would be quite sad... Especially at racing speeds.
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I thought they said 1700kg (Hagerty video)
The audience wasn't that close.
Man, you guys are nuts. Cables? really?
Remember when Elon announced a humanoid robot by using a dancer in a robot costume? Seems reasonable that he would have some "technical assistance" to make his stage show look great. No idea if it was cables or not, but reasonable people can doubt the veracity of the theatrics.
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I don't think the car in the video weighed even close to 1000kg.
This is very simple physics and has been done before by other cars. Most recently the McMurdo
It’s entirely real, and nothing “shocking” from a physics standpoint.
On todays to gear video they said the car weighs < 1700kg
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Really doubt that demo was on a 10k kg car. It was probably stripped down to practically a shell for that trick.
> 10k kg car
Did you typo this? Absolutely no way it's a 10 metric ton car.
Yeah sorry, it’s a typo