Raptor Engine - General Development Discussion and News

[Yggdrasill]

Makes sense it's film cooling. This time it looks like you have a layer of slower moving, more turbulent gas on the outside, that hasn't been there in the other videos/images.

Edit: (Actually looks a bit excessive. I would think they will dial that down in subsequent tests.)

 

[Grendal]

Article on the Raptor testing:
SpaceX's Starship engine hits twice the thrust of Merlin just days after test debut

 

[ecarfan]

Article on the Raptor testing:
SpaceX's Starship engine hits twice the thrust of Merlin just days after test debut

Wow! That’s amazingly rapid progress. Now if all the components will hold up over longer test cycles, and are truly reusable, the SpaceX team are going to go down in history as truly legnedary engineers.

 

[Grendal]

Wow! That’s amazingly rapid progress. Now if all the components will hold up over longer test cycles, and are truly reusable, the SpaceX team are going to go down in history as truly legnedary engineers.

They aren't messing around. This is like when they took the JSAT-8 booster with the very rough landing and immediately static fired it after recovery. Then they sent it to McGregor and static fired it there eight more times with full length cycles. They probably got a huge amount of data from that showing what parts degraded the quickest. That data eventually led to the very robust Block 5 booster. We can see the same thing happening here. It took Blue Origin almost a six months from the first test burn of the BE-4 to get to a 114 second 65% test. I'll guess at a full year before a full duration burn happened. No chance for that with SpaceX. I'll bet it's less than 2 months before we hear about a 100% test fire with as long as possible burn for that test stand.

 

[e-FTW]

Raptor engine manifold is Inconel (video): Elon Musk on Twitter

Photo: Elon Musk on Twitter

 

[HVM]

If you wondered why Raptor pressure graph stops here:

The answer for that:

Reagan Beck:
‏@bluemoondance74
"Have the most recent tests in McGregor been Merlins or Raptors? The last 4+ have seemed very similar... w/ one exception last wk (Fri. night)"

Elon Musk:
‏Verified account @elonmusk
"Merlins. The max chamber pressure run damaged Raptor SN 1 (as expected). A lot of the parts are fine for reuse, but next tests will be with SN 2, which is almost done."
Elon Musk on Twitter

(No Starhopper hops soon)

 

[ggr]

If you wondered why Raptor pressure graph stops here:
View attachment 379360

The answer for that:

Reagan Beck:
‏@bluemoondance74
"Have the most recent tests in McGregor been Merlins or Raptors? The last 4+ have seemed very similar... w/ one exception last wk (Fri. night)"

Elon Musk:
‏Verified account @elonmusk
"Merlins. The max chamber pressure run damaged Raptor SN 1 (as expected). A lot of the parts are fine for reuse, but next tests will be with SN 2, which is almost done."
Elon Musk on Twitter

(No Starhopper hops soon)

Why is the graph labeled "RD-180"?

 

[HVM]

Do they teach basic graph reading in the US schools? The solid grey line is the Russian RD-180 rocket engine's (used in Atlas V) pressure level (267 bar). The orange graph is Raptor's combustion chamber pressure. Raptor overtakes the industry leader's level at ~10.71 seconds, but that isn't so impressing as we know now, because Raptor SN 1 was damaged in the process.

Elon Musk‏Verified account @elonmusk
"Raptor reached 268.9 bar today, exceeding prior record held by the awesome Russian RD-180. Great work by @SpaceX engine/test team!"
Elon Musk on Twitter

 

[Grendal]

Do they teach basic graph reading in the US schools? The solid grey line is the Russian RD-180 rocket engine's (used in Atlas V) pressure level (267 bar). The orange graph is Raptor's combustion chamber pressure. Raptor overtakes the industry leader's level at ~10.71 seconds, but that isn't so impressing as we know now, because Raptor SN 1 was damaged in the process.

Elon Musk‏Verified account @elonmusk
"Raptor reached 268.9 bar today, exceeding prior record held by the awesome Russian RD-180. Great work by @SpaceX engine/test team!"
Elon Musk on Twitter

It's not bad for the first series of tests! I could be wrong but I think the 267 bar for the RD-180 is the best known pressure for the engine. I don't think it is its regular operating pressure. Looking it up, it seems the normal operating pressure is 262 bar.

 

[HVM]

AlexisG @Alexis_wwww
Replying to @katlinegrey @elonmusk

"Well, the thing is Musk is not in charge of the engine development, it's Tom Mueller" @lrocket


Tom Mueller @lrocket

"Not true, I am an advisor now. Elon and the Propulsion department are leading development of the SpaceX engines, particularly Raptor. I offer my 2 cents to help from time to time"

Tom Mueller on Twitter

Elon Musk✔ @elonmusk

"Tom did an awesome job leading Merlin, Kestrel, Draco & other engine developments from start through 2014 that were critical to SpaceX’s success. Great respect & appreciation!"

RaceFan22.
Replying to @bkent136 and 3 others

"To be fair, most engines that NASA uses are much better than the Merlin engine. Merlins are based off of engine designs from the '50s. Raptor on the other hand is one of the most advanced rocket engines ever developed."


Elon Musk✔ @elonmusk

"SpaceX Merlin architecture is simpler than staged combustion (eg SSME or RD), but it has world record for thrust/weight & thrust/cost engine. Raptor has better Isp, but I’m worried it may fall short on those two critical metrics."

Katya Pavlushchenko @katlinegrey

"Could you tell, how many people working now at Raptor development, except you? If it’s not classified of course."


Elon Musk✔ @elonmusk

"Rest of SpaceX propulsion still very active, so only ~50 full-time equivalent people right now. That will grow a lot as we enter production. It’s 10X harder (at least) to design engine production system than engine. In automotive, 100X harder."

Elon Musk on Twitter

 

[Grendal]

Lots of good stuff in this. Mostly about Raptor, show I'll put it here:

 

[HVM]

Elon Musk‏Verified account @elonmusk
Replying to @Erdayastronaut @flcnhvy

"Raptor liberated its oxygen turbine stator (appears to be mechanical, not metal combustion failure), so we need to update the design & replace some parts. Production is ramping exponentially, though. SN6 almost done. Aiming for an engine every 12 hours by end of year."

Elon Musk on Twitter

 

[ecarfan]

Thanks for posting that tweet from Elon. Good to hear that production is ramping up! As usual, Elon is setting an extremely ambitious goal.

 

[Grendal]

Thanks for posting that tweet from Elon. Good to hear that production is ramping up! As usual, Elon is setting an extremely ambitious goal.

That's awful strange for Elon...

-s

 

[HVM]

-Harry Stoltz
"~730 engines/year!! Wow!"

-Elon Musk
"Full year production is usually ~70% of peak daily rate, so 500/year. Still, non-trivial at 100,000 tons of thrust/year."

-Tim Dodd
"Cost wise, how much more expensive is Raptor than Merlin to produce? Twice as much? Three times-ish.... I estimated Raptor being around $2,000,000 but that was just a roughly educated guess."

-Elon Musk
"More than that now, but <10% of that in volume, although much to be proven"

-Tim Dodd
"...what specifically about raptor makes it anywhere near capable of that compared to previous engines?! Something about the seals / bearings / materials / full flow producing max enthalpy?"

-Elon Musk
"Other rocket engines were designed for no (or almost no) reuse. Raptor is designed for heavy & immediate reuse, like an aircraft jet engine, with inspections required only after many flights, assuming instrumentation shows it good. Using hydrostatic bearings certainly helps.

-Piotr Szmigielski
"What about Raptor turbines, they are designed to mitigate that issue?"

-Elon Musk
"Yes, they run at *much* higher pressure, but lower temperature. Thermal shock & strain are what fatigue Merlin turbine blades. Solvable for high reusability, but better to apply that engineering to Raptor."

 

[adiggs]

-Harry Stoltz
"~730 engines/year!! Wow!"

-Elon Musk
"Full year production is usually ~70% of peak daily rate, so 500/year. Still, non-trivial at 100,000 tons of thrust/year."

-Tim Dodd
"Cost wise, how much more expensive is Raptor than Merlin to produce? Twice as much? Three times-ish.... I estimated Raptor being around $2,000,000 but that was just a roughly educated guess."

-Elon Musk
"More than that now, but <10% of that in volume, although much to be proven"

-Tim Dodd
"...what specifically about raptor makes it anywhere near capable of that compared to previous engines?! Something about the seals / bearings / materials / full flow producing max enthalpy?"

-Elon Musk
"Other rocket engines were designed for no (or almost no) reuse. Raptor is designed for heavy & immediate reuse, like an aircraft jet engine, with inspections required only after many flights, assuming instrumentation shows it good. Using hydrostatic bearings certainly helps.

-Piotr Szmigielski
"What about Raptor turbines, they are designed to mitigate that issue?"

-Elon Musk
"Yes, they run at *much* higher pressure, but lower temperature. Thermal shock & strain are what fatigue Merlin turbine blades. Solvable for high reusability, but better to apply that engineering to Raptor."

It's interesting to me - I read this back and forth, and I'm thinking that Elon / SpaceX are solving engineering and production problems that others haven't started on, and there's a decent chance they don't even know that the problems exist.

On the plus side, stuff like this will help #2 chase fast and work through these problems more quickly than #1 is working through them.

 

[ICUDoc]

"Raptor liberated its oxygen turbine stator

Love the understated use of the word "liberated". A more elegant literary phrase in place of the awkward ugly geeky technical "RUD"

 

[HVM]

-Elon Musk @elonmusk
"Exciting progress in Boca! Hopper almost ready to hover. Based on tonight’s test, looks like 600 Hz Raptor vibration problem is fixed."
Elon Musk on Twitter

 

[mongo]

-Elon Musk @elonmusk
"Exciting progress in Boca! Hopper almost ready to hover. Based on tonight’s test, looks like 600 Hz Raptor vibration problem is fixed."
Elon Musk on Twitter

View attachment 427274

600? That's a lot of hurts.
Was it a nozzleation?
Just needed a little tuning (77Hz) for that C level engine performance.

Seriously, could the feed pipe dimensions and possibly combustion chamber create a resonance with the pumps?
Aka blowing over the top of a bottle/ Helmhotz resonator.
New version of pogo effect?

 

[HVM]

I would guess that it was related to the oxygen turbine stator issue.