Raptor Engine - General Development Discussion and News

[scaesare]

The most interesting bit for me was seeing the exhaust plume comparison of V2 and V3. It really communicates how much more power V3 is generating - and serves as a reminder that the more efficient a rocket engine is, the better is works as a weapon. I wonder if the new cooled plate would work with 33 V3 engines firing at it at full power.

The Exhaust plume is something that piqued my interest as well.

Previously we've seen well defined purple-hued plumes with shock diamonds. This is even more apparent in the "waterplate test video" in the other thread.

These appear much less well defined, which I suppose may be due to the more violent exiting as a result of the higher pressure. But the very orangish tint seems out of character for what we've see from a methalox engine...

 

[mongo]

The Exhaust plume is something that piqued my interest as well.

Previously we've seen well defined purple-hued plumes with shock diamonds. This is even more apparent in the "waterplate test video" in the other thread.

These appear much less well defined, which I suppose may be due to the more violent exiting as a result of the higher pressure. But the very orangish tint seems out of character for what we've see from a methalox engine...

Orange means more film cooling and/or richer mix overall which could be expected from a conservative first test.

 

[scaesare]

Given Elon's comments about the engine "really wanting to melt" it makes sense they cranked up the film cooling....

 

[scaesare]

Blue Origin's SLS BE-4 test summary tweet makes a point of the fact that each BE-4 produces 550,000 lbs of thrust.

That got me thinking about the recent Raptor test at 350 bar... it' producing 269 metric tons, or 592,000 lbs of thrust!

Pretty amazing when you compare the size of them (note previous Raptor version, #'s are incorrect, and it's even simpler/smaller now) :

 

[bxr140]

Blue Origin's SLS BE-4 test summary tweet makes a point of the fact that each BE-4 produces 550,000 lbs of thrust.

That got me thinking about the recent Raptor test at 350 bar... it' producing 269 metric tons, or 592,000 lbs of thrust!

Pretty amazing when you compare the size of them (note previous Raptor version, #'s are incorrect, and it's even simpler/smaller now) :

Raptor is a more edge-pushing design for sure; Blue was always going to be more conservative with their requirements and concepts. That said, there's a bit of purposeful (if not old school) conservatism on Blue's part in order to make reuse more tenable, not dissimilar to what Rocket Lab is doing with Archimedes. To analogize: That low-stressed V8 will run forever compared to a high strung turbo-4 doing the same amount of work.

SX has simply decided to make the turbo 4 just as reliable...by building a gazillion of them and iterating through weak links.

 

[mongo]

Raptor is a more edge-pushing design for sure; Blue was always going to be more conservative with their requirements and concepts. That said, there's a bit of purposeful (if not old school) conservatism on Blue's part in order to make reuse more tenable, not dissimilar to what Rocket Lab is doing with Archimedes. To analogize: That low-stressed V8 will run forever compared to a high strung turbo-4 doing the same amount of work.

SX has simply decided to make the turbo 4 just as reliable...by building a gazillion of them and iterating through weak links.

If the iterated turbo-4 is just as reliable, how does using a v8 make reuse more tenable?

Or are you saying Blue's dev environment wouldn't make a reliable turbo-4?

 

[scaesare]

Yeah, I expect pushing the envelope for chamber pressure, and operating on the edge of things "really wanting to melt" is not going to be the normal operational regime at this point... more so testing limits. While they have advanced ahead of Raptor's initial spec, I'm sure that the "normal" thrust level will be throttled some...

 

[bxr140]

If the iterated turbo-4 is just as reliable, how does using a v8 make reuse more tenable?

The level of effort (development staff, Capex, timeline, etc.) to get to ~equivalent reliability/work output on the former is, for an equivalent company at least, much higher than the latter.

 

[HVM]

Blue Origin's SLS BE-4 test summary tweet makes a point of the fact that each BE-4 produces 550,000 lbs of thrust.

That got me thinking about the recent Raptor test at 350 bar... it' producing 269 metric tons, or 592,000 lbs of thrust!

Pretty amazing when you compare the size of them (note previous Raptor version, #'s are incorrect, and it's even simpler/smaller now) :

View attachment 944970

Here's the updated version (in last image only nozzle diameters were from me). And, yes that's the Raptor V3 peak performance...

 

[scaesare]

Oh cool... I didn't catch the fact you built that, otherwise I would have attributed

Thanks... having the latest version on there helps illustrate that the new Raptors are making those #'s with even less mass/complexity...

 

[ecarfan]

Thanks @HVM ! Great diagram. Are there any publicly available numbers for the mass of the two engines?

Another data point is to compare the cost of each engine design. I think we know that a Raptor is about $1 million, correct? We don’t know what a BE-4 costs to build, but I’m pretty sure it is many multiples of that number.

 

[HVM]

There is no official mass figure for either engine. But Tim Dodd got Elon to give a ballpark number: 2,000 kg for Raptor 1 and 1,600 kg for 2. Sydney (Bing chat bot) told me that BE-4 weighs 3,500 kg, but that’s not in any sources. RD-180 mass is 5,480 kg so that’s not a bad guess. Two BE-4s should be heavier than a single RD-180.

We don’t know the cost, but ULA paid ~$25 million per RD-180, and the first pair of BE-4s was ~$16 million. Blue said it would be less when full production…

 

[mongo]

Thanks @HVM ! Great diagram. Are there any publicly available numbers for the mass of the two engines?

Another data point is to compare the cost of each engine design. I think we know that a Raptor is about $1 million, correct? We don’t know what a BE-4 costs to build, but I’m pretty sure it is many multiples of that number.

Raptor 1 was trending under $1 million in 2019. Goal was sub $250k for Raptor 2.

https://twitter.com/x/status/1179107539352313856

 

[scaesare]

I had not noticed this easter egg painted on the nozzle of Raptor #200 before, lol:

 

[ecarfan]

The latest NSF Starbase update video included this image, showing clearly just how much V3 Raptor plumbing has been simplified compared to previous versions. This Raptor is being installed into S28, likely the next Starship to fly after IFT-2.

 

[JohnSnowNW]

The latest NSF Starbase update video included this image, showing clearly just how much V3 Raptor plumbing has been simplified compared to previous versions. This Raptor is being installed into S28, likely the next Starship to fly after IFT-2.

View attachment 969036

That is ridiculous. Would love for someone to go into a deep dive on why all the plumbing was there on v1, and how the heck they were able to just delete 70% of it (so it seems to me).

 

[Grendal]

That is ridiculous. Would love for someone to go into a deep dive on why all the plumbing was there on v1, and how the heck they were able to just delete 70% of it (so it seems to me).

Maybe someone could give a quick overview, like Elon did for Tim Dodd for Raptor 1 to Raptor 2. However, I'm sure ITAR would prevent anyone from going into the details.

 

[JB47394]

That is ridiculous. Would love for someone to go into a deep dive on why all the plumbing was there on v1, and how the heck they were able to just delete 70% of it (so it seems to me).

One man's opinion:

Think of the V2 engine as a learning experience. As they discovered this problem or that, or wanted a bit more performance, they added a bit here, a bit there, a manifold here, a power line there. When they were content that they had found the right recipe, they were able to redesign the engine with all the lessons that they had learned. That meant that the manifold that controlled a variable pressure supply was gone, replaced by a single pipe with a specific geometry. And so on. They wouldn't want to go through the redesign process until they had found just the right recipe. They seem to think that the V3 engine is at the limit of what they can do with modern materials and technology, so it was time to lock down the design.

Some of it may also be instrumentation that was helping to drive the learning experience. Monitoring that manifold was important because they didn't know what its failure modes might be. But once they understood the problem, both the manifold and the instrumentation for it could be eliminated.

 

[scaesare]

I also wonder if they are taking a page from Tesla's handbook (or is that vice-versa?), and replacing multiple disparate parts assembled to accomplish a function with single integrated units? Fer example (again from Tesla):

The "Superbotle": Assemblydly replacing several cooling components needed for pack, drivetrain, and cabin cooling into a single package, eliminating multiple reservoirs, tubing, connectors, sensors, pumps and actuators.

The "Otcovalve": Also HVAC related, it replaces multiple valves, their motors, and the required plumbing with a single integrated package,

In both cases, they reduced part count, packaging space, assembly time, and cost. It looks simpler under the hood as well.

I wonder if they are at the point with Raptor that they are now beginning to do the same?

 

[scaesare]

Gah, my typos... must proofread when interrupted multiple times composing a post...