SpaceX Raptor: engines for super-rockets (thread 2)

[DocM]

First Raptor thread: https://www.neowin.net/forum/topic/1183837-spacex-raptor-large-methane-engine-updates/?view=getnewpost

OK - NOW we have CONFIRMED info from SpaceX about their super-heavy launcher plans and the engine that will power them.

Some things have changed, but the end game is STILL a mindblower. 800lb gorillas are pounding on the door.

One thing is certain: their main purpose is going to Mars, with perhaps a trip to the Moon just to prove capabilities (per Musk.)

I've filled in some gaps to flesh out the big new rocket motor, labeling or bracketing where.

(BFR =Big F'ing Rocket)

(Core diameter = stage width)

(S1 = first stage)

Raptor:

Full-Flow Staged Combustion (FFSC) engine

Dual independent shaft turbopumps

Propellants: Methane/liquid oxygen

Maximum thrust: 1,000,000 lbf (Merlin is 147,000 lbf)

What it means:

Full Flow Staged Combustion engines are very advanced. In very basic terms, Staged Combustion means the turbopump exhausts are recycled and run through the firing chamber to up efficiency. In a Full Flow Staged Combustion engine the turbopumps also run cooler because of a higher mass flow, they use high chamber pressures and are therefore compact for their power. They also differ by injecting their propellants as gases and not liquids. Russia calls them Gas-Gas because of this. FFSC's are also highly reusable.

The super-heavy rockets:

BFR because of no official names, yet. More info on these monsters in another thread dedicated to them. Images above created by a rocket engineer based on background info. The full images are stunning, but those are for later.

Single core BFR

A massively scaled-up Falcon 9 theme

Core diameter: 10m (32.8 feet)

S1: 9x Raptors in an Octaweb (8 in a circle, 1 in the center)

Tri-core BFR

A massively scaled-up Falcon Heavy theme

Core diameter: 10m (32.8 feet) x 3

S1: 27x Raptor in 3 Octawebs (O-O-O)

MCT: (Mars Colonial Transporter)

No specifics, still in dev. BIG. More later.

What it means:

Both BFR's will be more powerful than any rocket ever flown, or even NASA's Space Launch System. The tri-core by a LOT. No current launch pad on Earth could handle it, they would be heavily damaged or destroyed.

Raptor testing:

Work converting the NASA Stennis E3 (E Complex #3) test stand for methane component tests is almost finished, and SpaceX has been embedded for months.

Many outside rocket engineers speculate the full Raptor will be tested at NASA Stennis A Complex's A1 or A2 stands, not McGregor. We'll see.

There is also a contingent that sees indications there are already huge payloads for these beasts. A Bigelow Aerospace BA-2100 Olympus space station module (2x the volume of ISS), a govt./military payload, who knows?, but the vibe is palpable. People are scrounging recent conference reports for clues.

NASA Stennis test stands. The E Complex is in the foreground, the large A Complex stands are in the middle, and the B Complex is at the rear.

[flyingskippy]

What is the structure they are building just off to the right of the picture?

[DocM]

Looks like a new small test stand and water trench. Google Earth,

[flyingskippy]

Sorry, I gave a bad description of its location. I meant the one with the large steel structure with the two cranes near it.

[DocM]

That's one of the Complex A stands, where they tested Saturn V and shuttle main engines. Unless SpaceX builds a BIG new emgine stand at McGregor that's where they'll probably test Raptor.

There are also political considerations to testing Raptor at NASA Stennis; the congressman from that district is very influential, so keeping Stennis busy could help grease some wheels. Cheaper than building a new stand too.

[PaulRocket]

"Images above created by a rocket engineer based on background info. The full images are stunning, but those are for later. "

When or where can we find the entire picture?

[DocM]

The only rocket designer pics (non-SpaceX, he's Russian) in the public are outdated 10m core concepts. Raptor has grown since then, changing the tank capacities, and in a small format - being used in a promo by NASAspaceflight.com.

There are new ones, but they are very much in the black because of insider info. That and no one wants to give certain senators a heart attack.

Bear in mind, BFR has changed and the crew spacecraft is a placeholder as we don't know what the MCT crew vehicle looks like.

F9, Shuttle, FH, BFR crew, BFR cargo, BFR tri-core crew, Saturn V, BFR tri-core cargo

[PaulRocket]

Any guesses on how tall the BFR could be?

Elon said it would make the Saturn V look small.

[DocM]

Height isn't everything. There is also width.

When Raptor was still scaled at 1 million pounds of thrust (Tom Mueller's first statements) the stated configuration was 9 engines in a 10 meter wide core. A massively scaled up Falcon 9, which retains a similar avionocs. Makes sense.

With the numbers Mueller gave you can guesstimate the propellant burn rate, which combined with a ~3 minute first stage burn gives you the approximate propellant mass.

Apply basic geometry and it gives you a height a bit taller than Saturn V. The extra performance in BFR comes largely from the higher ISP (specific impulse) of methane and a lighter F9 like structure.

But then Raptor grew much more powerful. Full Flow Staged Combustion engines are very scaleable, and relatively small changes to the preburners can multiply power enormously without making the chamber larger. This happened in Raptors development.

More Raptor power means a higher propellant burn rate, and that means you need more of it to feed 9 of the beasts. There are only 3 ways to get larger tanks; go higher, go wider, or both. That is the stage vehicle development is at now.

If they keep the 10 meter diameter it means a skyscraper of a rocket, far exceeding Saturn V's 363.0 ft (110.6 m) height. That would mean a much larger and expensive ground support system; tower, vehicle transporter/erector etc. and a beast of a crane on the tower.

The alternative is to go much wider, perhaps a 14-16 meter core with a similar height as Saturn V. That keeps ground support within existing experience and cheaper. This also gives you a much wider payload fairing for habs etc., and a wider heat shield for crew vehicles.

Either, along with a MUCH larger payload capability, makes Saturn V look small.

[PaulRocket]

Ok, thanks. I guess we'll need to wait for the Falcon Heavy before we'll hear anything official from the BFR.

[DocM]

Then or a bit after. Their plate is pretty full what with launches, FH, F9R Dev-1/2, DragonFly, Dragon V2 abort tests etc. As AvWeek said, SpaceX is an R&D machine.

Falcon Heavy #1 is being built right now, and its partially underground (for acoustic control) test stand at McGregor is nearing completion. Tests later this year.

FH test stand a few weeks ago (from NASASpaceFlight.com)

Construction of the required FH facilities at Vandenberg started shortly after the F9 CASSIOPE launch, and the big machinery has started work converting KSC 39A for F9/FH.

Should see it fly in Q1 of 2015.

[ImUtrecht]

Funny thing was that some time ago i wrote about the suject of how tall the BFR could be on the forumsite of nasaspaceflight even quoting what Elon said that it would make saturn 5 look small. The experts there assured me that the BFR would be less tall than the Saturn 5. That i went against the so called rocket equasion etc. DocM knows what i am talking about.

But my point was that when Elon Musk says something i believe him, not the experts on the sideline.

 

I think that the BFR has a diametre of 10 metres, will be taller than 110 metres, could be around 125 metres will be a lot lighter thanks to innovative textiles and is rapid reusable.

The single core can lift around a 150 metric tonnes reusable and the tri core around 400 tonnes to LEO

The design will be based on the Falcon Heavy and the knowlegde they get through that project.

 

With the presentation of the Dragon 2 they already showed some of this technology

[DocM]

OK, the updated Raptor performance numbers given at the May Joint Propulsion Conference in Cologne, Germany have come out from the black.

They were behind an Aviation Week paywall but ULA posted them to their Daily Clipsheet blog, then they were posted to aerospace forums.

Point of reference is the Saturn V's Rocketdyne F-1 engine.

t = metric tonnes.

lbf = ft/lbs

Isp = efficiency, stated in seconds. Higher is better. 250 is OK, 300 is good, close to or over 400 is great. Propellant and engine design specific. 2-5 Isp points ARE significant.

Rocketdyne F-1 (Saturn V)

Propellants: RP-1 (kerosene)/LOX

Sea level thrust: 680.58t (1,500,000 lbf)

Vacuum thrust: not used in upper stage

Isp: 260 seconds

SpaceX Raptor (#'s may still be low)

Propellants: methane/LOX

Sea level thrust: 705t (1,554,259 lbf)

Vacuum thrust: 840t (1,851,883 lbf)

Isp: 380 seconds

9 Raptor engines in the first stage.

[PaulRocket]

Would the raptor have a blue flame? That would be sick!

[DocM]

Probably. This is XCOR 's methane engine,

[DocM]

Link....

L2 sources also note that parts for SpaceX?s next generation engine, the Raptor, are currently being 3D printed at the company?s Hawthorne base in California.

[DocM]

Sound like SpaceX is ready to cut metal for Raptor's powerhead!!

Rehashing, the last specs we heard were 1,550,000 lbf at sea level, 1,850,000 lbf in a vacuum. Minimum, since we don't know if they've ramped its flow up again.

http://www.spacex.com/careers/position/5985

>

RAPTOR TURBOPUMP BUILD ENGINEER

OVERVIEW:

As a Build Engineer at SpaceX you will have the opportunity to utilize your knowledge, experience and creativity on developing novel solutions at the cutting edge of space technology. You will work on launch vehicles and spacecraft that will deliver satellites into earth orbit, ferry humans to and from the international space station and ultimately extend humanitys reach beyond the earth and moon. You will own the relationship between our design and production teams. You will provide input into the design and development of new parts and take a lead role in manufacturing and integration of the part used on our current and next generation vehicles.

RESPONSIBILITIES

Responsible for fabrication, assembly, and testing of Raptor Turbopump parts, components, assemblies, and/or systems.

Work closely with design/development engineers and fabrications shops (internal and external) to get parts built and assembled.

Develop manufacturing and testing processes and procedures

Create and maintain a build schedule that lists all discrete fabrication and assembly tasks.

Ensure that all parts are fabricated or purchased at the correct time to facilitate the build schedule.

Participate in tool design and development.

Resolve manufacturing discrepancies and interface with the cross functional teams

Managing the transition of parts from development to production.

BASIC QUALIFICATIONS

Bachelor of Science in Aeronautical/Astronautical, Mechanical, Manufacturing, Industrial, or Production Engineering.

Candidates must have at least 1 year of hands-on fabrication, assembly, and/or testing experience (internship experience can supplement for the required industry experience).

Experience with metallic or composite manufacturing techniques, processes, equipment, and other processes such as machining, welding, tube bending, structural assembly, etc.

Experience with Unigraphics (UGS) and Teamcenter CAD.

PREFERRED SKILLS

Understanding of test methods/setups and data acquisition systems.

Experience generating, reading and interpreting engineering drawings

Experience with Design for Manufacture and Assembly.

Experience in a team oriented environment.

Must be able to work well in an integrated collaborative team environment including daily interactions with technicians, engineers, and managers.

Able to prioritize and execute tasks in a high-pressure environment.

Self-motivated and directed with keen attention to detail.

)

Must have an ongoing drive for continuous improvement in all aspects of work

ITAR REQUIREMENTS

To conform to U.S. Government space technology export regulations, applicant must be a U.S. citizen, lawful permanent resident of the U.S., protected individual as defined by 8 U.S.C. 1324b(a)(3), or eligible to obtain the required authorizations from the U.S. Department of State. Learn more about ITAR here.

>

[DocM]

ISPCS 2014 Keynote - SpaceX's Barry Matsumori. At about 14:35 he ID's the below attached engine graphic as a depiction of Raptor.

http://youtu.be/Hioda7c_CAc

[PaulRocket]

According to Elon Musks AMA on reddit, Raptor will have about 500 klbf of thrust per engine. Also Elon says that they will use a lot of them. He hopes to unveil the MCT and new spacesuits by the end of the year. I'm assuming that while he presents the MCT we will get too learn about Raptor. 

 

Read the full AMA here:

http://www.reddit.com/r/IAmA/comments/2rgsan/i_am_elon_musk_ceocto_of_a_rocket_company_ama/

[+Asmodai MVC]

According to Elon Musks AMA on reddit, Raptor will have about 500 klbf of thrust per engine. Also Elon says that they will use a lot of them. He hopes to unveil the MCT and new spacesuits by the end of the year. I'm assuming that while he presents the MCT we will get too learn about Raptor. 

 

Read the full AMA here:

http://www.reddit.com/r/IAmA/comments/2rgsan/i_am_elon_musk_ceocto_of_a_rocket_company_ama/

Isn't that WAY down from before?

Last Feb. Tom Mueller said Raptors target vacuum thrust was 8200 kilonewtons which is 1800 klbf. 500 klbf is more in line with what Blue Origin's BE-4 is targeting and the Raptor was supposed to be more than 3x as powerful.

[DocM]

This has caused MUCH discussion at NSF and it's L2 closed forum. SpaceX obviously changed plans.

What seems key here is that as you grow an engine it's mass grows disproportionately until it's thrust to weight (T/W) ratio is like that of the Saturn V's F1 engine: 94:1 or even less. SSME is 73:1 and RD-180 is 78.5:1. The RD-0146 is 38.4:1.

Contrast that with Merlin 1D at 160:1.

If the engine mass trades show a large enough T/W gap you can use more engines and still come out ahead.

A secondary factor is thrust levels when landing on Mars. A 1.85 mlbf engine would have to throttle very deeply to land, perhaps down to 10%. That's tough. A smaller engine could pull landings off without the need for ultra-deep throttling.

[PaulRocket]

Exactly, also they will use a lot of them. So we might see something like the N-1.

[DocM]

And using more engines, say 25-30, gives you an even more robust engine-out capability than Falcon 9 has - and that's pretty damned robust already.

Losing one Merlin 1D costs you 11% of your thrust, which can be made up by throttling up the remaining 8 and/or having them burn longer.

If you had a 30 engine BFR lose an engine it only costs you 3.33%. A hiccup.

A Falcon 9 v1.0 has already done this and its Dragon got to ISS 30 minutes early. An Antares didn't have enough engines to compensate and look what happened.

[+Asmodai MVC]

I thought the idea was that you'd be able to put a single big Raptor on the bottom of the Falcon 9 instead of the 9 smaller Merlin cluster.

Maybe not match the exact spec but be in the ballpark.

If one Raptor is only 500klbf then that doesn't even match 3 Merlins let alone get close to 9.  It's WAY off, I guess that means they're just going to scrap using Raptors on Falcon 9s at all.

Furthermore if they're really going for 500 then they may be beat by Blue Origin anyway.  Blue Origin is targeting 550 on the BE-4 but I have no idea what the cost comparisons are.

[DocM]

They never planned on using Raptor in Falcon or Falcon Heavy. Ever. It uses a different fuel and would require reengineering the whole thing. It's for a new family of launchers.