A few months ago SpaceX and Elon Musk were going to only make one version of the new Raptor engine for initial tests and flights but now Elon tweets that a vacuum optimized Raptor engine could be ready earlier.
A vacuum ready Raptor would be about 10-20% more fuel efficient in space and another version that would be more efficient at sea level.
The Raptors’s would be used in Starship launches. Starship is the upper stage of the fully reusable Super Heavy Starship that was called the BFR.
Starship with vacuum engines would have six Raptors instead of seven unoptimized engines. There would be three vacuum raptor engines and three sea level-optimized engines.
Space will start ramping to make three engines per day. The production ramp will start this summer but may not complete until end of 2019 or into 2020. They expect to have 100 Raptors built early in 2020.
About to complete SN5, ramping to an engine every 3 days this summer
— Elon Musk (@elonmusk) May 23, 2019
3 sea level optimized Raptors, 3 vacuum optimized Raptors (big nozzle)
— Elon Musk (@elonmusk) May 23, 2019
So RaptorVac is back on the table for nearer term launches?
— Eric Ralph (@13ericralph31) May 23, 2019
Aspirationally
— Elon Musk (@elonmusk) May 23, 2019
Hoping for 380 sec Isp, but at least 370. Otherwise similar to sea level version.
— Elon Musk (@elonmusk) May 23, 2019
SOURCES – Elon Musk Twitter, SpaceX
Written By Brian Wang, Nextbigfuture.com

Brian Wang is a Futurist Thought Leader and a popular Science blogger with 1 million readers per month. His blog Nextbigfuture.com is ranked #1 Science News Blog. It covers many disruptive technology and trends including Space, Robotics, Artificial Intelligence, Medicine, Anti-aging Biotechnology, and Nanotechnology.
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Wrong. It’s the billons in shareholder $$ poached under the pretence of developing something new… it’s called the Shuttle…techs been around for 3 decades. Space X employees are living in the Matrix…
The DearMoon design with the center engine and the hexaweb, with the cargo compartments around the outside? That’s not a design that can accommodate any vac engines.
But you still have to pick a specific thrust structure and flow it through the rest of the design. The SL and vac engines are not interchangeable because the vac engines are so much wider.
And I have visions of an exponentially greater version of that, when I see anyone say something to the effect of; “We need to get all the world / humanity together in one space program!”
“So, you want yet another layer of bureaucracy on top of that which we* already have?”
(*And the space agencies of those nations that have one…not that every nation has something to bring to the table, anyway.)
He’s also not building something to a government SOW. That’s a huge part of why they’re able to operate this way. If they win EELV, they won’t be able to run the EELV-version of the F9 development cycle in that way because they’ll have get 3 forms of USAF approval to change the bleach they clean the bathrooms with.
Doing everything under one roof and also doing it as an IRAD program where the government is not your customer are the two biggest reasons why Space X is able to be agile. You can’t be agile when the federal government is your customer because the federal government is the slowest, least agile organization imaginable.
I work on a large missile defense program and while I agree that Space X shows how space program development can be done and is something to be mulated by the rest of the industry — it’s important to understand that this is not exactly NASA’s fault so much as the fault of the government customer, how it runs, and secondarily the fault of slow, clunky subcontractor relationships. Probably 90% of the aeronautics industry is governed by the prime/sub organizational structure, it is exceedingly rare that a large defense or space development program is designed, integrated and tested under one roof. I’m not even talking about tiny outsourcing like; for instance, we buy a hydraulic testing cart from a local hydraulics shop. I’m talking about how half a missile is built by Lockheed and the other half by someone else. This kind of relationship, often mediated extremely poorly by the government – is what makes these design cycles incredibly slow and unresponsive.
I say this because it’s important to understand that certain types of dev programs simply can’t be operated the way Space X operates by virtue of having to get the government approval for anything.
The BFS was always intended to have vacuum engines included. They removed them to cut development times, but I’m pretty sure the longer-term intention never changed. So they’re probably designing everything with the vacuum engine in mind, just not sure if they’ll have the engine itself ready for the early test versions of the BFS.
The required safety margin of 1.4 of their equally aspirational human rating allows for both.
Yes on purpose, but Musk has said going public was a mistake.
Spacex is making NASA look like a Space-Coast nursing home.
Also because Tesla is a publicly traded company and SpaceX isn’t and that was on purpose.
This seems weird. Surely somebody has to make decisions about the thrust structure pretty soon. Everything else (plumbing, wiring, avionics, structural engineering, etc.) depends on it. So saying that RaptorVac is “aspirational” has to be at least a little bit disingenuous. It’s either in or it’s out.
Wow, that sure sounds like the way tesla is run, except that the SEC (government) gets involved and screws it all up.
It’s the only company Musk gave up some control of, to the government and the only one in trouble(because of that loss of control).
In a government agency, the most important thing is to cover your ass, so you don’t get blamed if something goes wrong. So you have lots of meetings, reports, and sign-offs by everyone involved. This obviously takes time.
Musk has a controlling interest in SpaceX. He’s bot nobody to blame but himself for a bad decision. But the speed of progress saves huge amounts of money over the government way.
We used to have a saying in aerospace that when the weight of the documentation equals the weight of the product, its ready to fly. When I was working on the space station program at Boeing, this was literally true. Our documents vault filled half the basement of one of our engineering buildings, and the mass of paper down there was easily as much as the flight hardware weighed.
Last year I saw an interview with a NASA engineer who got loaned to SpaceX. He said he sat in a meeting with Musk and a dozen others over some technical decision, and argued one side of it. By the end he convinced Musk, who said “ok, we’ll do it that way.”
Engineer was stunned. He said NASA would have had another dozen meetings over the course of months before actually deciding.
Since SpaceX now seems to be thinking about launching Starship SSTO tests from 39a, it must be thinking about putting in methane storage there too, which would also happen to support a vacuum raptor second stage for Falcon.
With that sort of raptor production including vacuum raptors I’d wonder if they’re thinking about making the Falcon second stages using them like that USAF contract study. That would improve Falcon’s performance quite a bit and eliminate the need to keep Merlin production going once they build out the necessary fleet of Block 5 reusable boosters.
Not three per day, one every three days. 2 per week would be about 100 per year which would be enough for SpaceX in 2019-2020, but 100 by early 2020 implies closer to twice that rate since they’d be making 100 in about half a year. 100 is a lot. That’s 2 Superheavy boosters and 6 Starships.
The good thing of having a goal oriented, agile environment is that they can change things from one day to the other.
Something that in traditional space programs could add months or years of delay due to over-analysis and design by committee, could be made by a small group or a single expert decision maker.
And over SpaceX, I think E. Musk is the ultimate decision maker, even if the managers and designers obviously have their say.