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Cont: Musk, SpaceX and future of Tesla II

acbytesla said:
The value of us ever going to the moon is debatable. Although the program itself created many ancillary benefits. That said, it was very expensive. About 5% of the US budget for more than a decade. That's one hell of lot of bridges, tunnels, roads and schools that could have been built.
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So do you have any evidence that not spending money on going to the moon would have resulted in more bridges, tunnels, roads and schools?

It is not an either/or situation.

The money spent on going to the moon didn't go to the moon. It went to people here on Earth.
 
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JayUtah said:
That's true, but historically that hasn't been too much overhead. The Apollo ascent engine used supercritical helium to maintain propellant tank pressure. Storing the pressurant as a liquid reduces tanking and plumbing, which is the real mass penalty. The Apollo APS fuel pressurization system had a total filled mass of less than 10 kg. That's on a spacecraft with a dry mass of 2,000 kg.
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Does that include the liquid oxygen in the Saturn rockets?
 
acbytesla said:
Does that include the liquid oxygen in the Saturn rockets?
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No. That's just the ascent stage of the lunar module. The launch vehicle has entirely different engineering. When you have cryogenic propellants, you can use the boil-off from the propellant as the pressurant gas, which is how pretty much all LOX systems work.

ETA: For a tank volume of 1000 m3 you would need about 180 kg of helium to pressurize it to 1 atmosphere up until total depletion. I think that's about the upper limit we can expect from a Starship tanker. Add 100 kg of tankage and plumbing and you have under 300 kg of mass for a spacecraft with a dry mass of > 160,000 kg. But if the tank holds cryogenic liquid, just use the boil-off.
 
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JayUtah said:
No. That's just the ascent stage of the lunar module. The launch vehicle has entirely different engineering. When you have cryogenic propellants, you can use the boil-off from the propellant as the pressurant gas, which is how pretty much all LOX systems work.
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I sort of knew it wasn't. The Saturn rockets were huge. And there was a second and if I remember correctly a third stage.
 
The Saturn V lunar landing configuration used LOX/RP-1 on the S-IC (first) stage and LOX/LH2 on the S-II (second) and S-IVB (third) stages. And yes, this was a huge launch vehicle with lots of issues in managing the various liquids it contained.

The restartable J-2 engine on the lunar S-IVB was especially fun. Not only do you need a way to repeatedly ignite propellants, you need a way to settle the propellants to the bottom of the tanks so that the pumps can take a bite of it. The Saturn V generally used ullage motors: solid rockets that operated at staging to push the new stage ahead and settle the propellants inertially. Thereafter the acceleration kept it going. The Apollo LM ascent could count on the motor starting in lunar gravity, which settles the propellant. To restart the APS they would need an ullage burn from the RCS, as did the Service Module. The S-IVB had its own RCS-type assembly so that it could be steered remotely from the ground after flight, and it could supply ullage. One of the companies around where I work had a casing from the S-IVB auxiliary, but it was all dented up. The S-IVB also had solid ullage motors for its initial ignition after S-II staging. You can tell from the staging footage which stage type it was. The lunar-qualified restartable S-IVBs have three ullage motors while the test and cargo versions only had two.

Skylab was basically just a hollowed-out S-IVB. The lower tank was retained as the hygeinic slop tank (ew!). But the entire habitable volume of the Skylab station was just one of the propellant tanks on the smallest stage of the Saturn V.
 
jeremyp said:
I found a positive story about Tesla!

electrek.co

Tesla is gearing up to sell its electric semi truck, poaches key sales executives from rivals

Tesla is quietly but significantly expanding its Tesla Semi sales team, bringing on two seasoned veterans from the electric trucking...
electrek.co electrek.co

They are recruiting sales people to sell the Semi which means that maybe they are ready to start production.
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LOL- half a decade late....

1764854417873.png
Note the date at the bottom.....

And of course they are far from the only ones...
1764854533099.png
1764854682473.png
1764854769947.png

Walk in, open your wallet and drive out, I could literally be in one tomorrow afternoon....
And of course, musk is as popular as ◊◊◊◊◊◊◊ on your shoes in most of the world, and has literally zero experience with heavy haulage and its requirements.....
 
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JayUtah said:
The Saturn V lunar landing configuration used LOX/RP-1 on the S-IC (first) stage and LOX/LH2 on the S-II (second) and S-IVB (third) stages. And yes, this was a huge launch vehicle with lots of issues in managing the various liquids it contained.

The restartable J-2 engine on the lunar S-IVB was especially fun. Not only do you need a way to repeatedly ignite propellants, you need a way to settle the propellants to the bottom of the tanks so that the pumps can take a bite of it. The Saturn V generally used ullage motors: solid rockets that operated at staging to push the new stage ahead and settle the propellants inertially. Thereafter the acceleration kept it going. The Apollo LM ascent could count on the motor starting in lunar gravity, which settles the propellant. To restart the APS they would need an ullage burn from the RCS, as did the Service Module. The S-IVB had its own RCS-type assembly so that it could be steered remotely from the ground after flight, and it could supply ullage. One of the companies around where I work had a casing from the S-IVB auxiliary, but it was all dented up. The S-IVB also had solid ullage motors for its initial ignition after S-II staging. You can tell from the staging footage which stage type it was. The lunar-qualified restartable S-IVBs have three ullage motors while the test and cargo versions only had two.

Skylab was basically just a hollowed-out S-IVB. The lower tank was retained as the hygeinic slop tank (ew!). But the entire habitable volume of the Skylab station was just one of the propellant tanks on the smallest stage of the Saturn V.
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Thanks for that informed summary of the problems of refuelling in space. There has been a lot of development of solutions and how to deal with the problems.

SpaceX has gone for the simplest solution, pressure differential. How does that work with multiple tankers trying to refuel a starship in LEO since each new tanker faces a higher pressure in the target? The number of tankers required is also very open to guesswork.
 
a_unique_person said:
SpaceX has gone for the simplest solution, pressure differential. How does that work with multiple tankers trying to refuel a starship in LEO since each new tanker faces a higher pressure in the target? The number of tankers required is also very open to guesswork.
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I don't know the details of their proposed operation. But if you're in space, you can always depressurize something. Liquid fuel is essentially incompressible. You can't add any more liquid to a tank that's entirely full of liquid, a condition called "going solid" when this happens in industrial processes. To get pressure in a tank that's meant to hold a liquid, you have to leave some room for a gas, the "pressurant," which can be compressed and thereby squeezed tighter as more liquid is pumped into the tank. The tank pressure comes from this gas, and naturally it will increase as you force more liquid in and squeeze the pressurant into a tighter volume. But in space there's no reason why you can't vent off that pressurant as you go so that it maintains a constant pressure—say, just high enough to keep the liquid fuel from vaporizing. As long as you leave some pressurant there and don't "go solid" on the tank, you're fine.
 
Dabop said:
And of course, musk is as popular as ◊◊◊◊◊◊◊ on your shoes in most of the world, and has literally zero experience with heavy haulage and its requirements.....
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Mary Barra (CEO of GM) was elected to the National Academy of Engineering in February 2018. In 2023 she was inducted into the Automotive Hall of Fame. She definitely knows her stuff. When Biden was crediting her for leading the industry towards EVs, she pulled him aside and said "Actually, I think a lot of that credit goes to Elon and Tesla". Other industry leaders have made similar comments. Musk's popularity with the general public doesn't seem to bother them. Mind you, most them are careful not to let their political views become known. For all we know Mary Barra could be a secret Nazi!

When Tesla announced plans to develop the Semi in 2016 they may have had zero experience with heavy haulage, but they learned fast. They hired Jérôme Guillen - former project leader for the Freightliner Cascadia program and Director of Business Innovation at Daimler - to lead the team, and by November 2017 a concept prototype was unveiled. The current lead for the Semi program is Dan Priestly, who has been a Tesla engineer since 2015. I wonder how they would characterize your insinuation that Tesla "has literally zero experience with heavy haulage and its requirements".

Production of the Semi was planned to begin in 2019, but in January 2020 Musk said a lack of battery production capability was a limiting factor. Then Covid happened. The Tesla Semi entered pilot production in 2022. As usual with Tesla they have been doing extensive trials to get feedback from users. PepsiCo was the first to receive them, hauling food products up to 425 miles. By all accounts PepsiCo is very happy with their performance, and the drivers love them. As of May 2024 Walmart, Costco, Sysco, Martin Brower, and US Foods were also testing the Semi. Tesla has also been using the Semi for their own operations.

By the time it enters full-scale production the Semi should be as good as or better than any Electric truck on the market. In August 2024 logistics provider NFI tested the Semi and reported an efficiency of 1.64 kWh/mi (1.02 kWh/km). According to Volvo the FH does 1.76 kWh/mile (1.1 kWh/km) with a range of up to 186 miles (300km) - less than half the Tesla Semi's real-world range.

Good to see other truck makers producing EVs, but one look at them tells you they aren't as innovative as Tesla. One Chinese company is making what looks like an exact copy though. Tesla should be pleased with this too, as their goal is to 'accelerate the world's transition to sustainable energy'. To this end Tesla has opened many of their patents to other companies (I bet the bean counters hate that). Musk never intended Tesla to take over the market, but to encourage the entire industry to go electric.

When the Semi goes big it will be just in time to go fully autonomous like Musk originally planned, then it could be a real 'game changer'. If Tesla's plans pan out things could get pretty wild. Imagine convoys of autonomous trucks plying the roads with robots in the back, waiting to load and unload goods made in factories manned by robots (with a small group of humans overseeing and maintaining them). This isn't science fiction, but a very real possibility in the near future (like next year). Tesla isn't the only one working on these technologies, but they are the only one putting it all together.

That's Musk's doing - only he has the vision and drive to make it all happen. You can hate his politics, but don't let it taint your evaluation of Tesla's achievements. Mary Barra didn't, despite GM being one of Tesla's main competitors.
 
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Roger Ramjets said:
Mary Barra (CEO of GM) was elected to the National Academy of Engineering in February 2018. In 2023 she was inducted into the Automotive Hall of Fame. She definitely knows her stuff. When Biden was crediting her for leading the industry towards EVs, she pulled him aside and said "Actually, I think a lot of that credit goes to Elon and Tesla". Other industry leaders have made similar comments. Musk's popularity with the general public doesn't seem to bother them. Mind you, most them are careful not to let their political views become known. For all we know Mary Barra could be a secret Nazi!
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Nobody is denying that Tesla takes a lot of the credit for popularising EVs and making them viable in the eyes of the public. Musk's role is less clear. Most of the key decisions were taken before he joined and, if the text of Eberhard's lawsuit is to be believed, Musk was a liability except that he provided some capital.

The problem today is not what Tesla and Musk did in the past, but what they are doing now.

Roger Ramjets said:
When Tesla announced plans to develop the Semi in 2016 they may have had zero experience with heavy haulage, but they learned fast. They hired Jérôme Guillen - former project leader for the Freightliner Cascadia program and Director of Business Innovation at Daimler - to lead the team, and by November 2017 a concept prototype was unveiled. The current lead for the Semi program is Dan Priestly, who has been a Tesla engineer since 2015. I wonder how they would characterize your insinuation that Tesla "has literally zero experience with heavy haulage and its requirements".
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Putting the driver's seat in the middle of the cab was pretty daft. If that's the level of experience, it's not much.

It was clear at launch that Musk knew nothing about the haulage industry since he concentrated on telling everybody how fast the semi is, not on its load capacity.

Roger Ramjets said:
Production of the Semi was planned to begin in 2019, but in January 2020 Musk said a lack of battery production capability was a limiting factor. Then Covid happened. The Tesla Semi entered pilot production in 2022. As usual with Tesla they have been doing extensive trials to get feedback from users. PepsiCo was the first to receive them, hauling food products up to 425 miles. By all accounts PepsiCo is very happy with their performance, and the drivers love them. As of May 2024 Walmart, Costco, Sysco, Martin Brower, and US Foods were also testing the Semi. Tesla has also been using the Semi for their own operations.

By the time it enters full-scale production the Semi should be as good as or better than any Electric truck on the market. In August 2024 logistics provider NFI tested the Semi and reported an efficiency of 1.64 kWh/mi (1.02 kWh/km). According to Volvo the FH does 1.76 kWh/mile (1.1 kWh/km) with a range of up to 186 miles (300km) - less than half the Tesla Semi's real-world range.

Good to see other truck makers producing EVs, but one look at them tells you they aren't as innovative as Tesla. One Chinese company is making what looks like an exact copy though. Tesla should be pleased with this too, as their goal is to 'accelerate the world's transition to sustainable energy'. To this end Tesla has opened many of their patents to other companies (I bet the bean counters hate that). Musk never intended Tesla to take over the market, but to encourage the entire industry to go electric.
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By the time the Semi is in full scale production, other manufacturers will be on the next iteration of their trucks. Tesla is behind and with its product development cycles (at least 10 years for the semi), it is going to fall further and further behind.

By the way, all the nonsense about accelerating the transition to sustainable energy is just marketing bull. Musk doesn't care about sustainable energy: if he did, Tesla wouldn't have invested into BTC.

Roger Ramjets said:
When the Semi goes big it will be just in time to go fully autonomous like Musk originally planned,
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It's that far behind schedule is it? That's worse than I thought.

Roger Ramjets said:
then it could be a real 'game changer'. If Tesla's plans pan out things could get pretty wild. Imagine convoys of autonomous trucks plying the roads with robots in the back, waiting to load and unload goods made in factories manned by robots (with a small group of humans overseeing and maintaining them). This isn't science fiction, but a very real possibility in the near future (like next year). Tesla isn't the only one working on these technologies, but they are the only one putting it all together.
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Robots for manufacturing already exist. Tesla is way behind on that front. In fact, Tesla is still stuck in the mindset of making them look like humans. All the other manufacturers know that this is not the way to go.

Roger Ramjets said:
That's Musk's doing - only he has the vision and drive to make it all happen. You can hate his politics, but don't let it taint your evaluation of Tesla's achievements. Mary Barra didn't, despite GM being one of Tesla's main competitors.
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There's very little evidence that Musk's positive contribution to Tesla is anything more than money.
 
JayUtah said:
None of the robots we use look like humans, nor need to. That doesn't stop the manufacturing team from putting googly eyes on them and giving them names.
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i remember an art display i had seen years ago that was a pretty large fanuc robot with a giant sock over it and googly eyes that talked. pretty cool stuff
 
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