14 ms·

In 2019, Elon tweeted[0] that the price of one Raptor engine is under $1M with the goal going under 250K for the next version. Any recent info where there are n

In 2019, Elon tweeted[0] that the price of one Raptor engine is under $1M with the goal going under 250K for the next version. Any recent info where there are now? I'm still surprised they moved to this orbital fly so quickly without doing more tests. Going from 3 engines to almost 30 is crazy. Also, If I understand it right, both booster and starship will end up in the ocean. I hope they will be able to reuse at least a few engines. [0] https://twitter.com/elonmusk/status/1179107539352313856 https://twitter.com/elonmusk/status/1179107539352313856

Ajedi32 5y ago
No further word on costs as far as I'm aware, other than that <$1000/ton of thrust is still the goal long-term: https://twitter.com/elonmusk/status/1420826978102435845 https://twitter.com/elonmusk/status/1420826978102435845
- jhgb 5y ago
  Considering that cost-wise, they're already putting the RS-25 to shame (https://arstechnica.com/science/2020/05/nasa-will-pay-a-staggering-146-million-for-each-sls-rocket-engine/ https://arstechnica.com/science/2020/05/nasa-will-pay-a-stag...), this seems more like an icing on the cake.
  - lutorm 5y ago
    Given that you could probably build a Merlin out of solid gold and it would come in cheaper than an RS-25, that's not exactly saying much...
    - piercebot 5y ago
      Maybe not once you consider the R&D costs of figuring out how not to melt a solid gold Merlin engine ;)
      - lutorm 5y ago
        There is that... ;-)
      - jjoonathan 5y ago
        This man (err, bot?) contracts!
      - Tuna-Fish 5y ago
        ... surprisingly, this is not much of an issue. The key property for keeping a rocket engine from melting is not high melting point, but high thermal conductivity. Because of this, all the parts that touch the hot flame are made from a copper alloy, with a melting point not far from that of pure gold. In the chamber, the hot gases are >3500K, and touching the inner walls with a melting point at ~1400K, yet the walls don't melt, because they are cooled with more power than they are heated.
        jhgb 5y ago
        > they are cooled with more power than they are heated I'd argue that they're being cooled with equal power, otherwise they could freeze infinitely which is physically impossible.
    - Ajedi32 5y ago
      Wow, no kidding. The gold Merlin would be a quarter of the price![1][2][3] (At least in terms of materials.) [1]: https://arstechnica.com/science/2020/05/nasa-will-pay-a-staggering-146-million-for-each-sls-rocket-engine/ https://arstechnica.com/science/2020/05/nasa-will-pay-a-stag... [2]: https://www.google.com/search?q=merlin+engine+dry+mass https://www.google.com/search?q=merlin+engine+dry+mass [3]: https://www.wolframalpha.com/input/?i=%28630+kg+of+gold+in+USD%29+%2F+%24146+million https://www.wolframalpha.com/input/?i=%28630+kg+of+gold+in+U...
      - mlindner 5y ago
        Keep in mind gold is a lot denser, so it'd be a miniature engine if you made it out of pure gold. If you take the volumetric space of all the materials that might lead to a different answer, but that's hard to do. (I guess you could make it out of gold foam.)
        Ajedi32 5y ago
        Probably closer to half the price of the RS-25 then, assuming normal Merlins are made mostly out of steel: https://www.wolframalpha.com/input/?i=%28%28%28630+kg+*+%28density+of+gold+%2F+density+of+steel%29%29+*+price+of+gold%29+%2F+%24146+million https://www.wolframalpha.com/input/?i=%28%28%28630+kg+*+%28d...
    - Diederich 5y ago
      I LOLd but then had to do the math. Turns out that the dry weight of a SpaceX Merlin engine, in gold, costs almost exactly the same as a production RS-25. Current spot price of gold is $1800/oz. Merlin dry weight is 1380 pounds. 1380 pounds of gold is right at 40 million dollars. Per https://en.wikipedia.org/wiki/RS-25#Space_Shuttle_program https://en.wikipedia.org/wiki/RS-25#Space_Shuttle_program : "A total of 46 reusable RS-25 engines, each costing around US$40 million, were flown during the Space Shuttle program" Beautiful.
      - jhgb 5y ago
        They cost much more than $40M these days.
      - mlindner 5y ago
        Those numbers are out of date now, they recently restarted production and it turns out each engine is about $150M now for the new production run for the SLS. (Which about the cost of a full expendable Falcon Heavy rocket launch along with all 27 of its Merlin engines.)
        mr_toad 5y ago
        That’s what happens when you decide on a product and then ask how much it costs.
908B64B197 5y ago
Only in America things like this can happen. A whole industry bootstrapping itself to make semi-conductors doubling every 18 months, going from exotic, mission critical hardware to commodity; SpaceX is doing the same thing with flight hardware. Contrast that with previous generation engines (the RS-25 comes to mind) with a sticker price of 125 millions... per engine! [0] [0] https://spacenews.com/aerojet-rocketdyne-defends-sls-engine-contract-costs/ https://spacenews.com/aerojet-rocketdyne-defends-sls-engine-...
- tablespoon 5y ago
  >> Only in America things like this can happen. > Semi-Conductor doubling every 18 months IIRC, the recent doublings have been happening in Taiwan. That's why people make such a big deal about TMSC. America (i.e. Intel) actually has some catching up to do.
  - cma 5y ago
    EUV LLC. that their current nodes are based on was started in America through DARPA, DoE, and a US industry consortium. That's why we are still allowed to enforce export restrictions on EUV tech via ASML, even though it is European.
    - tablespoon 5y ago
      Maybe so, but Intel hasn't been able to make it work yet, unlike TMSC.
- piercebot 5y ago
  What is it about America (or other countries) that makes you think this couldn't happen anywhere else?
  - foxyv 5y ago
    Personally, I think it has a lot to do with American sub-culture, the US dollar, our crazy university system, and immigration. This is speculation on my part so take it with a BIG grain of salt. The USA brings in 50 million or so people from other countries. Often they are bloody minded, stone cold, hard workers that will sacrifice everything to give their children the opportunity to be Americans. These people are some of the best in the world in my opinion. The US dollar being used as a reserve currency for most of the world means that it is the center of international investment. This means that the billions of dollars that flowed into PayPal and Elon Musk's startups probably came in large part from foreign investment funds. Our universities crank out some of the weirdest and least conventional engineers you can imagine. Most of them are half-crazy in the first place. The archetype of Mad Scientist can be found in physics departments and engineering labs all over the country. Conformity is often seen as a kind of perversity. We idolize professors like Feynman and read novels like Ignition! This is why you see bridges collapsing and power grids failing while we build some of the most advanced technology in the world. We hate boring maintenance and love to launches cars into space. Finally in no small part is American sub-culture. Specifically the science fantasy of space travel and colonization that is in the heart of a lot of American engineers and scientists. The same fantasy that captured the heart of Elon Musk, a billionaire South African immigrant who made his fortune in Silicon Valley. In addition there is the added fact that few other countries would allow some random small company to build ICBMs in their metaphorical backyard. The USA is kinda loose like that...
gpm 5y ago
> Also, If I understand it right, both booster and starship will end up in the ocean. You mean for the first test flight? Do you have a source? Long term plan is definitely land landing, but I haven't seen anything about the first test flight. I assumed that they would try and land it from the start, they've already landed starship a few times, and it seems like that's where a lot of the unknowns still are (e.g. they're apparently adjusting wing size down after the last landing)?
- gridspy 5y ago
  The test flight trajectories are posted with the FAA and covered in numerous places, for instance Article: https://spaceflightnow.com/2021/05/13/spacex-outlines-plans-for-around-the-world-starship-test-flight/ https://spaceflightnow.com/2021/05/13/spacex-outlines-plans-... Video (Marcus House): https://youtu.be/9-9k513UIVw?t=298 https://youtu.be/9-9k513UIVw?t=298 Basically both vechicles (the massive booster and the starship itself (2nd stage) are going to "land" on the water, which means a hover and then sinking into the water. Booster - Boost and separate, boostback burn and splashdown off the coast. Starship - 90 min orbit at about 120km, reentry and spashdown near Hawaii It's fairly quite likely that both would crater on this first flight - for instance this is the first booster flight and also the first reentry for the starship itself. The Falcon 9 booster also had similar flight plans until it could successfully fly a controlled trajectory to the surface of the ocean before they risked a drone ship too.
  - gpm 5y ago
    Thanks :)
  - milansuk 5y ago
    Yep, this is what I meant, thanks for the sources. Although, I'm not sure about that "then sinking into the water" part. There are big LO2 and methane tanks and If they are empty enough and closed, both Starship and Booster shouldn't sink. I guest, we'll see it soon.
    - krisoft 5y ago
fiftyfifty 5y ago
This is hardly beyond standard practice in the industry. The SLS is going to orbital flight with no flight testing. Heck the Falcon Heavy launched a car past Mars' orbit on it's first flight. I think SpaceX's main goal was to refine their manufacturing process and make sure they can achieve a certain level of consistency in building these things. The fact that they installed all these Raptors before even doing a pressure test tells you they are far more confident in their processes than they were even 6 months ago.
- repsilat 5y ago
  > hardly beyond standard practice in the industry. The SLS is Perhaps explaining GP's surprise: I've heard SpaceX's testing philosophy contrasted against this sort of thing. That none of their tests are "too big to fail". On the other hand, according to this narrative they also stress iteration speed over success rate, and ramping up fast works to that end too. Maybe they were getting diminishing returns (in terms of lessons learnt) in small scale tests though. No doubt there are phenomena you only see in larger tests, and (as you say) their confidence in getting the smaller stuff right might be quite high.
perihelions 5y ago
"I'm still surprised they moved to this orbital fly so quickly without doing more tests." I'll bet they're going to remove all 29 of these engines and re-attach them again later. I would expect they want much more testing than they've done to date (for example, pressure testing the tanks -- they have not done that with this booster, BN4, according to Reddit).

Ajedi32 5y ago

No further word on costs as far as I'm aware, other than that <$1000/ton of thrust is still the goal long-term: https://twitter.com/elonmusk/status/1420826978102435845 https://twitter.com/elonmusk/status/1420826978102435845

jhgb 5y ago
Considering that cost-wise, they're already putting the RS-25 to shame (https://arstechnica.com/science/2020/05/nasa-will-pay-a-staggering-146-million-for-each-sls-rocket-engine/ https://arstechnica.com/science/2020/05/nasa-will-pay-a-stag...), this seems more like an icing on the cake.
- lutorm 5y ago
  Given that you could probably build a Merlin out of solid gold and it would come in cheaper than an RS-25, that's not exactly saying much...
  - piercebot 5y ago
    Maybe not once you consider the R&D costs of figuring out how not to melt a solid gold Merlin engine ;)
    - lutorm 5y ago
      There is that... ;-)
    - jjoonathan 5y ago
      This man (err, bot?) contracts!
    - Tuna-Fish 5y ago
      ... surprisingly, this is not much of an issue. The key property for keeping a rocket engine from melting is not high melting point, but high thermal conductivity. Because of this, all the parts that touch the hot flame are made from a copper alloy, with a melting point not far from that of pure gold. In the chamber, the hot gases are >3500K, and touching the inner walls with a melting point at ~1400K, yet the walls don't melt, because they are cooled with more power than they are heated.
      - jhgb 5y ago
        > they are cooled with more power than they are heated I'd argue that they're being cooled with equal power, otherwise they could freeze infinitely which is physically impossible.
  - Ajedi32 5y ago
    Wow, no kidding. The gold Merlin would be a quarter of the price![1][2][3] (At least in terms of materials.) [1]: https://arstechnica.com/science/2020/05/nasa-will-pay-a-staggering-146-million-for-each-sls-rocket-engine/ https://arstechnica.com/science/2020/05/nasa-will-pay-a-stag... [2]: https://www.google.com/search?q=merlin+engine+dry+mass https://www.google.com/search?q=merlin+engine+dry+mass [3]: https://www.wolframalpha.com/input/?i=%28630+kg+of+gold+in+USD%29+%2F+%24146+million https://www.wolframalpha.com/input/?i=%28630+kg+of+gold+in+U...
    - mlindner 5y ago
      Keep in mind gold is a lot denser, so it'd be a miniature engine if you made it out of pure gold. If you take the volumetric space of all the materials that might lead to a different answer, but that's hard to do. (I guess you could make it out of gold foam.)
      - Ajedi32 5y ago
        Probably closer to half the price of the RS-25 then, assuming normal Merlins are made mostly out of steel: https://www.wolframalpha.com/input/?i=%28%28%28630+kg+*+%28density+of+gold+%2F+density+of+steel%29%29+*+price+of+gold%29+%2F+%24146+million https://www.wolframalpha.com/input/?i=%28%28%28630+kg+*+%28d...
  - Diederich 5y ago
    I LOLd but then had to do the math. Turns out that the dry weight of a SpaceX Merlin engine, in gold, costs almost exactly the same as a production RS-25. Current spot price of gold is $1800/oz. Merlin dry weight is 1380 pounds. 1380 pounds of gold is right at 40 million dollars. Per https://en.wikipedia.org/wiki/RS-25#Space_Shuttle_program https://en.wikipedia.org/wiki/RS-25#Space_Shuttle_program : "A total of 46 reusable RS-25 engines, each costing around US$40 million, were flown during the Space Shuttle program" Beautiful.
    - jhgb 5y ago
      They cost much more than $40M these days.
    - mlindner 5y ago
      Those numbers are out of date now, they recently restarted production and it turns out each engine is about $150M now for the new production run for the SLS. (Which about the cost of a full expendable Falcon Heavy rocket launch along with all 27 of its Merlin engines.)
      - mr_toad 5y ago
        That’s what happens when you decide on a product and then ask how much it costs.

908B64B197 5y ago

Only in America things like this can happen. A whole industry bootstrapping itself to make semi-conductors doubling every 18 months, going from exotic, mission critical hardware to commodity; SpaceX is doing the same thing with flight hardware. Contrast that with previous generation engines (the RS-25 comes to mind) with a sticker price of 125 millions... per engine! [0] [0] https://spacenews.com/aerojet-rocketdyne-defends-sls-engine-contract-costs/ https://spacenews.com/aerojet-rocketdyne-defends-sls-engine-...

tablespoon 5y ago
>> Only in America things like this can happen. > Semi-Conductor doubling every 18 months IIRC, the recent doublings have been happening in Taiwan. That's why people make such a big deal about TMSC. America (i.e. Intel) actually has some catching up to do.
- cma 5y ago
  EUV LLC. that their current nodes are based on was started in America through DARPA, DoE, and a US industry consortium. That's why we are still allowed to enforce export restrictions on EUV tech via ASML, even though it is European.
  - tablespoon 5y ago
    Maybe so, but Intel hasn't been able to make it work yet, unlike TMSC.
piercebot 5y ago
What is it about America (or other countries) that makes you think this couldn't happen anywhere else?
- foxyv 5y ago
  Personally, I think it has a lot to do with American sub-culture, the US dollar, our crazy university system, and immigration. This is speculation on my part so take it with a BIG grain of salt. The USA brings in 50 million or so people from other countries. Often they are bloody minded, stone cold, hard workers that will sacrifice everything to give their children the opportunity to be Americans. These people are some of the best in the world in my opinion. The US dollar being used as a reserve currency for most of the world means that it is the center of international investment. This means that the billions of dollars that flowed into PayPal and Elon Musk's startups probably came in large part from foreign investment funds. Our universities crank out some of the weirdest and least conventional engineers you can imagine. Most of them are half-crazy in the first place. The archetype of Mad Scientist can be found in physics departments and engineering labs all over the country. Conformity is often seen as a kind of perversity. We idolize professors like Feynman and read novels like Ignition! This is why you see bridges collapsing and power grids failing while we build some of the most advanced technology in the world. We hate boring maintenance and love to launches cars into space. Finally in no small part is American sub-culture. Specifically the science fantasy of space travel and colonization that is in the heart of a lot of American engineers and scientists. The same fantasy that captured the heart of Elon Musk, a billionaire South African immigrant who made his fortune in Silicon Valley. In addition there is the added fact that few other countries would allow some random small company to build ICBMs in their metaphorical backyard. The USA is kinda loose like that...

gpm 5y ago

> Also, If I understand it right, both booster and starship will end up in the ocean. You mean for the first test flight? Do you have a source? Long term plan is definitely land landing, but I haven't seen anything about the first test flight. I assumed that they would try and land it from the start, they've already landed starship a few times, and it seems like that's where a lot of the unknowns still are (e.g. they're apparently adjusting wing size down after the last landing)?

gridspy 5y ago
The test flight trajectories are posted with the FAA and covered in numerous places, for instance Article: https://spaceflightnow.com/2021/05/13/spacex-outlines-plans-for-around-the-world-starship-test-flight/ https://spaceflightnow.com/2021/05/13/spacex-outlines-plans-... Video (Marcus House): https://youtu.be/9-9k513UIVw?t=298 https://youtu.be/9-9k513UIVw?t=298 Basically both vechicles (the massive booster and the starship itself (2nd stage) are going to "land" on the water, which means a hover and then sinking into the water. Booster - Boost and separate, boostback burn and splashdown off the coast. Starship - 90 min orbit at about 120km, reentry and spashdown near Hawaii It's fairly quite likely that both would crater on this first flight - for instance this is the first booster flight and also the first reentry for the starship itself. The Falcon 9 booster also had similar flight plans until it could successfully fly a controlled trajectory to the surface of the ocean before they risked a drone ship too.
- gpm 5y ago
  Thanks :)
- milansuk 5y ago
  Yep, this is what I meant, thanks for the sources. Although, I'm not sure about that "then sinking into the water" part. There are big LO2 and methane tanks and If they are empty enough and closed, both Starship and Booster shouldn't sink. I guest, we'll see it soon.
  - krisoft 5y ago

fiftyfifty 5y ago

This is hardly beyond standard practice in the industry. The SLS is going to orbital flight with no flight testing. Heck the Falcon Heavy launched a car past Mars' orbit on it's first flight. I think SpaceX's main goal was to refine their manufacturing process and make sure they can achieve a certain level of consistency in building these things. The fact that they installed all these Raptors before even doing a pressure test tells you they are far more confident in their processes than they were even 6 months ago.

repsilat 5y ago
> hardly beyond standard practice in the industry. The SLS is Perhaps explaining GP's surprise: I've heard SpaceX's testing philosophy contrasted against this sort of thing. That none of their tests are "too big to fail". On the other hand, according to this narrative they also stress iteration speed over success rate, and ramping up fast works to that end too. Maybe they were getting diminishing returns (in terms of lessons learnt) in small scale tests though. No doubt there are phenomena you only see in larger tests, and (as you say) their confidence in getting the smaller stuff right might be quite high.

perihelions 5y ago

"I'm still surprised they moved to this orbital fly so quickly without doing more tests." I'll bet they're going to remove all 29 of these engines and re-attach them again later. I would expect they want much more testing than they've done to date (for example, pressure testing the tanks -- they have not done that with this booster, BN4, according to Reddit).