3 ms·

Pure novelty. Subs are not energy efficient. Water is 1,000x more dense than air, & moving through it takes far more energy. And, hybrid (land+water) is goin

Pure novelty. Subs are not energy efficient. Water is 1,000x more dense than air, & moving through it takes far more energy. And, hybrid (land+water) is going to require far more hardware, driving up the price & weight (& thus efficiency) of a vehicle. But, it's cool & he has the budget & gumption for it, so THANKS Elon, for keeping us entertained!

saraid216 13y ago
Clearly, it's actually a flying car. The car will leave the water and the juice will at that point be able to manage lift off.
Florin_Andrei 13y ago
It seems to me like this is his equivalent of a hobby or week-end project. So I wouldn't try to read too much into it. Yet.
- zerooneinfinity 13y ago
  Even Linux was a 'hobby weekend project' at one point.
  - gcb0 13y ago
    didn't he started that for university credits?
baddox 13y ago
> Subs are not energy efficient. Water is 1,000x more dense than air, & moving through it takes far more energy. I don't disagree that this is impractical, and you could be right that subs are inefficient, but the density argument alone doesn't seem sufficient, because propellers (and presumably other means of propulsion) also generate a lot more lift in water than in air.
- Retric 13y ago
  It's really speed dependent, at the correct altitude and RPM propellers can be 85+% efficient in air. Also, while boats can get 'free' lift in water at speed your much better off with a wing aka hydrofoil because drag is one of those nasty velocity^3 things that quickly dominates. So while a 2mph sub is more energy efficent than a 200mph aircraft the sub is rather impractical even pushing the sub to 20mph means the aircraft wins.
  - stcredzero 13y ago
    The Russians had cavitating rocket driven torpedoes that traveled at 100's of miles per hour. 2 mph might be fine for a billionaire's private submarine yacht. If you're a billionaire and you're in a hurry, just transfer to the private jet.

saraid216 13y ago

Clearly, it's actually a flying car. The car will leave the water and the juice will at that point be able to manage lift off.

Florin_Andrei 13y ago

It seems to me like this is his equivalent of a hobby or week-end project. So I wouldn't try to read too much into it. Yet.

zerooneinfinity 13y ago
Even Linux was a 'hobby weekend project' at one point.
- gcb0 13y ago
  didn't he started that for university credits?

baddox 13y ago

> Subs are not energy efficient. Water is 1,000x more dense than air, & moving through it takes far more energy. I don't disagree that this is impractical, and you could be right that subs are inefficient, but the density argument alone doesn't seem sufficient, because propellers (and presumably other means of propulsion) also generate a lot more lift in water than in air.

Retric 13y ago
It's really speed dependent, at the correct altitude and RPM propellers can be 85+% efficient in air. Also, while boats can get 'free' lift in water at speed your much better off with a wing aka hydrofoil because drag is one of those nasty velocity^3 things that quickly dominates. So while a 2mph sub is more energy efficent than a 200mph aircraft the sub is rather impractical even pushing the sub to 20mph means the aircraft wins.
- stcredzero 13y ago
  The Russians had cavitating rocket driven torpedoes that traveled at 100's of miles per hour. 2 mph might be fine for a billionaire's private submarine yacht. If you're a billionaire and you're in a hurry, just transfer to the private jet.