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Starship Update [video]

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Re: Starship Update [video]

#161

Post by dvirsky »

irrational wrote: post #6

This is the first time I’ve ever heard him speak. Is he always this awkward? Based off of the 5 minutes I watched, he clearly hasn’t gotten to where he is through charisma and public speaking skills. I’m just wondering if this is typical for him. Also, a million tons to Mars? If each starship lifts 100 tons, that is 10,000 launches. I think he said launch windows only come around every 2 years. He is either planning…

I think the tension between how successful he is and how awkward he is, _is_ a key part of his charisma.

Re: Starship Update [video]

#162

Post by shthed »

mattr47 wrote: post #67
irrational wrote: post #6

This is the first time I’ve ever heard him speak. Is he always this awkward? Based off of the 5 minutes I watched, he clearly hasn’t gotten to where he is through charisma and public speaking skills. I’m just wondering if this is typical for him. Also, a million tons to Mars? If each starship lifts 100 tons, that is 10,000 launches. I think he said launch windows only come around every 2 years. He is either planning…

He was born autistic.

Aspergers

Re: Starship Update [video]

#164

Post by mchusma »

giantrobot wrote: post #91
irrational wrote: post #49

Earlier quoted context omitted.

The basic idea is to not have all your eggs in one basket. We are one asteroid strike away from losing all human life on earth. Having 2 habited planets spreads the risk. Obviously having those planets in different solar systems would be even better, but we don’t have the technology for that, yet.

> We are one asteroid strike away from losing all human life on earth. We're one asteroid strike from losing all human life in the solar system even if you had a bunch of people living on Mars. It would take a very long time to get even a single Mars colony self sufficient. Without resources of Earth supporting the colony it would die out the first time the air conditioner broke. Putting people on Mars isn't putting…

Musk says basically this in his presentation. Very very hard.

Re: Starship Update [video]

#165

Post by gpm »

iliketrains wrote: post #156
ewjt wrote: post #124

Earlier quoted context omitted.

I thought 100k HP was either too incredible or a typo. Then I looked it up: “You def don’t want electric pumps on a rocket engine! Raptor turbopumps alone need 100,000 horsepower per engine. That’s not a typo.” —Elon Musk x 32 engines. Amazing! For comparison, this is an internal combustion engine with 100k HP: https://www.zmescience.com/science/biggest-most-poweful-engi...

That is interesting, so could you replace the biggest and most powerful internal combustion engine in the world that weighs 2,300 tons by [whatever powers] turbopumps from a raptor engine and get the same power output? Where is the catch? Less fuel efficient? Less torque? Edit: What I meant to ask was: Can one use "whatever is powering the turbopumps and delivering the 100k HP" to power say a ship propeller, instead…

It's a totally different problem.

Yes it's less efficient, you spent all this energy cooling off all the fuel and oxidizer to cryogenic temperatures before using it. The turbopumps in the raptors are also running very far off from stochiometric fuel mixtures (which is fine in the rocket because they're exhaust is used as fuel for the next stage) - which means if you're just using it for the pump your not actually burning most of the fuel. The exhaust is also really hot, and if you're not somehow using that energy it's definitely inefficient.

None of those issues matter to the rocket. Energy used on the ground to cool down propellants is "free", the colder the better because it means you can fit more propellants in the same tanks. The exhaust is just being piped into the main combustion chamber, so it will eventually be fully combusted extracting the left over chemical energy. The heat of the exhaust (after the main chamber) is the whole point, with a nozzle converting it into kinetic energy.

You've also got a bunch of safety issues. High pressures, liquid oxygen, and so on.

Re: Starship Update [video]

#166

Post by pmontra »

inasio wrote: post #108
panick21_ wrote: post #33

The Raptor 2 engine is just an absurd. The original specs were already kind of insane. But Raptor 2 is an monster. They really pushed already significantly into a second generation design before first flight. Raptor 2 is not just a slight upgrade, its a huge upgrade. If it can actually launch multiple times a day without any refurbishment, it will simply totally break space travel as we have known it. This engine mak…

My theory is that they aim to disrupt Earth travel (airlines). Elon pointed out that the reliability of Starship would exceed that of commercial airplanes, and the fuel costs are not that different than, say, a 747. Fewer moving parts than an airplane, less human costs, order of magnitude faster...

I'm not sure that this will ever be viable for the general population. Think about the acceleration at launch and reentry. It's more an amusement park experience than travel by car, ship or plane. There will be people mentally and physically fit for that (past some age and before another one) and people that will never be.

Other problems like cost, time from home to spaceport and boarding can be fixed or be irrelevant (if I live too far away, too bad for me, I'll fly.)

Re: Starship Update [video]

#167

Post by jltsiren »

proggy wrote: post #157
inasio wrote: post #108

Earlier quoted context omitted.

My theory is that they aim to disrupt Earth travel (airlines). Elon pointed out that the reliability of Starship would exceed that of commercial airplanes, and the fuel costs are not that different than, say, a 747. Fewer moving parts than an airplane, less human costs, order of magnitude faster...

Concerns about cost per flight aside, how would one go about locating spaceports near enough to urban centers for this concept to be viable? If a fully fueled airliner crashes in an urban area, it’s devastating. Now consider a fully fueled rocket — would the crash be an order of of magnitude worse? Perhaps I still have the “rockets are inherently dangerous, mitigate bad outcomes by isolating them” mentality. Maybe de…

There are many safety and security issues that must be solved before suborbital passenger flights become viable. Some involve national security. For example, can you imagine a world where the US, Russia, and China keep launching ICBMs at each other all the time?

Others involve more mundane risks that are pretty much guaranteed to occur once in a while. Things like losing cabin pressure or something catching fire. How do you deal with such situations, how quickly can you get the rocket to land safely, and how quickly can you evacuate the passengers?

Re: Starship Update [video]

#168

Post by bagels »

iliketrains wrote: post #156
ewjt wrote: post #124

Earlier quoted context omitted.

I thought 100k HP was either too incredible or a typo. Then I looked it up: “You def don’t want electric pumps on a rocket engine! Raptor turbopumps alone need 100,000 horsepower per engine. That’s not a typo.” —Elon Musk x 32 engines. Amazing! For comparison, this is an internal combustion engine with 100k HP: https://www.zmescience.com/science/biggest-most-poweful-engi...

That is interesting, so could you replace the biggest and most powerful internal combustion engine in the world that weighs 2,300 tons by [whatever powers] turbopumps from a raptor engine and get the same power output? Where is the catch? Less fuel efficient? Less torque? Edit: What I meant to ask was: Can one use "whatever is powering the turbopumps and delivering the 100k HP" to power say a ship propeller, instead…

The turbopump on its own won't do anything. The turbopump takes the 100k hp, and uses that to compress fuel and liquid oxygen. It's powered by the engine. It doesn't produce power on its own.

Re: Starship Update [video]

#169

Post by gpm »

etrautmann wrote: post #121
inasio wrote: post #108

Earlier quoted context omitted.

My theory is that they aim to disrupt Earth travel (airlines). Elon pointed out that the reliability of Starship would exceed that of commercial airplanes, and the fuel costs are not that different than, say, a 747. Fewer moving parts than an airplane, less human costs, order of magnitude faster...

Elon seemed to indicate that it would be stretching to get individual launch costs below $1M. That seems at least 2-3 orders of magnitude out of range for most conventional travel?

I believe that $1M includes the booster stage, and that for suborbital p2p travel you should be able to skip that. The booster consumes the majority of the fuel, has a lot more engines (which require upkeep), and so on.

$1M for an orbital flight strikes me as an insanely aggressive target, but if they can achieve that, they can probably achieve half that, or less, for suborbital hops.

Re: Starship Update [video]

#170

Post by gpm »

bagels wrote: post #168
iliketrains wrote: post #156

Earlier quoted context omitted.

That is interesting, so could you replace the biggest and most powerful internal combustion engine in the world that weighs 2,300 tons by [whatever powers] turbopumps from a raptor engine and get the same power output? Where is the catch? Less fuel efficient? Less torque? Edit: What I meant to ask was: Can one use "whatever is powering the turbopumps and delivering the 100k HP" to power say a ship propeller, instead…

The turbopump on its own won't do anything. The turbopump takes the 100k hp, and uses that to compress fuel and liquid oxygen. It's powered by the engine. It doesn't produce power on its own.

IIRC it's powered by a relatively small in size pre-burner - and I think it's fair to assume that he was including that pre-burner in his comparison.
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