Author Topic: Blue Origin's BE-7 engine (Read 96580 times)

Nilof · « **on:** 05/10/2019 05:27 am »

Blue origin announced a new hydrolox engine, the BE-7, which will power the Blue Moon lander, and should also be versatile enough to be used for other applications.

Here's what we learned from presentation + website:

Dual expander cycle.
Thrust: 40 kN
Specific impulse: 453 s
Propellant: LH2 + LOX

Deep throttle capability for lunar landings. Parts are mostly 3D printed. If you see more technical details pop up, post them here.

vaporcobra · « **Reply #1 on:** 05/10/2019 05:32 am »

First static fire is "later this year".

Nilof · « **Reply #2 on:** 05/10/2019 05:41 am »

WANTED INFO: Biggest unknown piece of information for this engine is the O/F (oxidizer to fuel) ratio. Will be added here if found.

Since the main application is for a lunar lander and LOX ISRU is easy on the entire moon, the O/F ratio is important info for any mission payload calculations that assume oxygen depots. The O/F ratio could also be variable like the J-2, in which case we would be interested in the whole range.

If we ever get a situation where you can ask Bezos or a Blue representative random questions about technical details, this would be a great one to ask.

FutureSpaceTourist · « **Reply #3 on:** 05/10/2019 08:35 am »

Re-posting in this thread for ease of reference:

https://twitter.com/erdayastronaut/status/1126594675048157185

Quote

This is @blueorigin’s BE-7 engine for the #bluemoon lunar lander up close and personal!

tonya · « **Reply #4 on:** 05/10/2019 02:14 pm »

Just from the way the pumps and control valves are mounted, it looks like something that was designed with servicing in mind as a design objective. Quite striking how simple it looks and how accessible and obvious the major components are.

Nilof · « **Reply #5 on:** 05/10/2019 04:01 pm »

Quote from: FutureSpaceTourist on 05/10/2019 08:35 am

Re-posting in this thread for ease of reference:

https://twitter.com/erdayastronaut/status/1126594675048157185

Quote
This is @blueorigin’s BE-7 engine for the #bluemoon lunar lander up close and personal!

Following up on Tonya's comment, note how the pipes are color coded depending on whether they carry hydrogen or oxygen.

Also, this is a good opportunity to link to this nice educational article about expander cycle engines:
https://blogs.nasa.gov/J2X/2014/03/24/inside-the-leo-doghouse-the-art-of-expander-cycle-engines/

And attached, a diagram of the dual expander cycle:

Nilof · « **Reply #6 on:** 05/10/2019 04:12 pm »

Link to presentation starting exactly at engine unveil:

https://www.youtube.com/watch?v=GQ98hGUe6FM?t=2369

Also includes a rotating view of the engine so that you can view it from all angles. Looking at the oxidizer turbopump, that definitely looks like a split expander cycle on the oxidizer side, since the pump seems to have two stages.

Also looking at the pipes to propellant tanks, it looks like the engine provides autogenous pressurization? That would definitely be an advantage of going with a split expander, since you get hot GOX and GH2 for free which can be used to pressurize the propellant tanks.

tonya · « **Reply #7 on:** 05/10/2019 05:03 pm »

Plumbing screengrabs for easier reference.

russianhalo117 · « **Reply #8 on:** 05/10/2019 08:15 pm »

Quote from: Nilof on 05/10/2019 04:01 pm

Quote from: FutureSpaceTourist on 05/10/2019 08:35 am
Re-posting in this thread for ease of reference:

https://twitter.com/erdayastronaut/status/1126594675048157185

Quote
This is @blueorigin’s BE-7 engine for the #bluemoon lunar lander up close and personal!

Following up on Tonya's comment, note how the pipes are color coded depending on whether they carry hydrogen or oxygen.

Also, this is a good opportunity to link to this nice educational article about expander cycle engines:
https://blogs.nasa.gov/J2X/2014/03/24/inside-the-leo-doghouse-the-art-of-expander-cycle-engines/

And attached, a diagram of the dual expander cycle:

The only thing that we don't know is the exact type of dual expander cycle (DEC) engine although it seems to be the simplest type of DEC when viewing the display engine, but the display engine may not be a final complete fidelity engine.

Reference video:

Scott Manley' s take:

Rik ISS-fan · « **Reply #9 on:** 05/10/2019 09:54 pm »

AFAIK the BE-7 uses the most complex expander-cycle option; the dual expander cycle.
The most simple is expander bleed; aka evaporating some of the fuel or oxidizer to drive the turbopump(s). The evaporated gas is dumped in the trust direction, but not used inside the combustion chamber.
The next level in complexity is a standard expander cycle, the fuel or the oxidizer is evaporated, drives the turbopump(s) and is injected into the combustion chamber. The most complex is dual expander, both the fuel and oxidizer are expanded, they drive a fuel and oxidizer turbopump and the gasses are injected into the combustion chamber, reaching the high ISP of the GOxGH2 fuel combo.
(RL-10 has a geared GH2(G) turbine driving a LH2 turbopump connected with a gear to the LO2 turbopump.
Vince has a LOx and a LH2 turbopump both driven by a GH2 turbine. With a proportional valve the GH2 flow is regulated between the two turbopumps. Now in Europe the ETID is being developed under the ESA FLPP program, it uses another version of the single expander cycle (afaik).

Have others envisioned the use of BE-7 as upper-stage engine for a New Shepard sized and derived small launcher? AKA ~1000-2000lb (0.5-1mT) to 800km SSO. Is this possible?

Edit to add: Blue Origin what is the thust level of BE-7. 10k lbf (44 482 N) or 40kN (8992 lbf)?
The current numbers are a mess. If its 10k lbf state its 44,5kN please.
Note that BE-- is a very small low thrust engine. RL-10 is 15k - 25k lbf (~65-110kN), and Vince is 180kN (~40 500 lbf). And the Ariane 5 ECA HM7B gasgenerator engines provide ~64kN (14.3k lbf) so BE-7 is less powerful.
What I find funny is the fact that the Callisto demonstrator (Europa and Japan reusable suborbital stage demonstrator) will use re-ignitable 40kN LOxLH2 engine. Details about this engine are vague.

edit2: the engine shown on the right side if the Scott Manley Expander Cycle video, is NOT Vince. Its ID#1 the thust chamber test article from the EDIT FLPP project.

DasBlinkenlight · « **Reply #10 on:** 05/10/2019 10:41 pm »

IN all of the photos, I don't see where the propellants first enter the system...
Also trying to determine how they will start the BE-7... both ignition, and getting the expander cycles started... I don't see any gas generator or other means of starting.... any ideas?

russianhalo117 · « **Reply #11 on:** 05/10/2019 10:58 pm »

Quote from: Rik ISS-fan on 05/10/2019 09:54 pm

AFAIK the BE-7 uses the most complex expander-cycle option; the dual expander cycle.
The most simple is expander bleed; aka evaporating some of the fuel or oxidizer to drive the turbopump(s). The evaporated gas is dumped in the trust direction, but not used inside the combustion chamber.
The next level in complexity is a standard expander cycle, the fuel or the oxidizer is evaporated, drives the turbopump(s) and is injected into the combustion chamber. The most complex is dual expander, both the fuel and oxidizer are expanded, they drive a fuel and oxidizer turbopump and the gasses are injected into the combustion chamber, reaching the high ISP of the GOxGH2 fuel combo.
(RL-10 has a geared GH2(G) turbine driving a LH2 turbopump connected with a gear to the LO2 turbopump.
Vince has a LOx and a LH2 turbopump both driven by a GH2 turbine. With a proportional valve the GH2 flow is regulated between the two turbopumps. Now in Europe the ETID is being developed under the ESA FLPP program, it uses another version of the single expander cycle (afaik).

Have others envisioned the use of BE-7 as upper-stage engine for a New Shepard sized and derived small launcher? AKA ~1000-2000lb (0.5-1mT) to 800km SSO. Is this possible?

Edit to add: Blue Origin what is the thust level of BE-7. 10k lbf (44 482 N) or 40kN (8992 lbf)?
The current numbers are a mess. If its 10k lbf state its 44,5kN please.
Note that BE-- is a very small low thrust engine. RL-10 is 15k - 25k lbf (~65-110kN), and Vince is 180kN (~40 500 lbf). And the Ariane 5 ECA HM7B gasgenerator engines provide ~64kN (14.3k lbf) so BE-7 is less powerful.
What I find funny is the fact that the Callisto demonstrator (Europa and Japan reusable suborbital stage demonstrator) will use re-ignitable 40kN LOxLH2 engine. Details about this engine are vague.

edit2: the engine shown on the right side if the Scott Manley Expander Cycle video, is NOT Vince. Its ID#1 the thust chamber test article from the EDIT FLPP project.

Let's use the most complex variant of DEC known CDSEC or Closed Dual Split Expander Cycle which is the theoretically most powerful, optimized, and efficient version of DEC for ideally upper stage uses as a sustainer engine. The display engine presently shows the simplest variant of DEC.

Rik ISS-fan · « **Reply #12 on:** 05/10/2019 11:09 pm »

I think the mock-up of BE-7 misses the sensor and electronic cables and the LOx and LH2 infeeds. The mockup only only shows: four sections of the combustion chamber assembly; the GOx and GH2 lines and regulator valves.
The engine for Callisto must be able to throttle down 40% or to 40% (40kN max => 24kN or 16kN |10k lbf => 6k or 4k lbf)

@russianhelo117 can you explain the difference between DEC and CDSEC? What is de spilt meaning?
The BE-7 definitely looks like a closed cycle engine. And AFAIK the schemetic you show has lower ISP because some of the fuel and oxidizer will be injected in liquid form instead of all gas, what the BE-7 has.

I've added a screenshot with the back side of the BE-7, several unused sensor and feed-line ports are visible.
I think this looks like a dual tap-off expander cycle. All fuel and lox are evaporated inside the double walled combustion chamber. Some of the expanded fuel and oxidizer are used to drive the turbopumps to increase gas injection pressure into the combustion chamber.
Edit3: The liquid pumps and liquid propellant lines are missing in the rendering. I think there are blinding plates mounted in the place of the liquid turbines. This looks like a test engine with pre pressurized liquid propellants.

russianhalo117 · « **Reply #13 on:** 05/10/2019 11:29 pm »

Quote from: Rik ISS-fan on 05/10/2019 11:09 pm

I think the mock-up of BE-7 misses the sensor and electronic cables and the LOx and LH2 infeeds. The mockup only only shows: four sections of the combustion chamber assembly; the GOx and GH2 lines and regulator valves.
The engine for Callisto must be able to throttle down 40% or to 40% (40kN max => 24kN or 16kN |10k lbf => 6k or 4k lbf)

@russianhelo117 can you explain the difference between DEC and CDSEC? What is de spilt meaning?
The BE-7 definitely looks like a closed cycle engine.

It fixes deficiencies in a standard Closed DEC, eliminates the need for boost pumps and other manipulations for effective combustion at the MCC. The fuel side is identical to the oxidizer side in term of components, albeit adjusted for the fuel type. Like its FFSCC cousin, CDSEC is highly efficient at the tradeoff of being the most complex version of an EC engine and the fact that the engine would have to be tested like Raptor as the entire engine. Boost pumps can be added for higher thrust without the losses of bleed Cycle engines.
Scrolldown and read:
https://blogs.nasa.gov/J2X/2014/03/24/inside-the-leo-doghouse-the-art-of-expander-cycle-engines/

Lar · « **Reply #14 on:** 05/11/2019 01:00 am »

I just wanna say I love that guy[1] and his diagrams, his writing makes me smile a lot."happy little turbopumps" indeed... And now I understand the tradeoffs around expanders a lot better. Do we have enough images to tell which variant the BE-7 is? are both sides split?

1 - I refer to the link Nilof gave, here it is again: https://blogs.nasa.gov/J2X/2014/03/24/inside-the-leo-doghouse-the-art-of-expander-cycle-engines/

Nilof · « **Reply #15 on:** 05/11/2019 01:40 am »

To me it looks like the BE-7 is split on the oxidizer side but not the fuel side, which is necessary because you have a lot more LOX flow than LH2 flow mass-wise, and you wouldn't want to push that much LOX through the engine walls.

The LOX side pump has five pipes going into it and is longer (meaning it's split), while the LH2 pump is stubby and has four pipes going into it.

Also, while it may have more complex plumbing, the Dual expander should have fewer moving parts & be simpler mechanically since it doesn't need a gearbox between LH2 turbopump and LOX pump, and also doesn't need crazy seals on the bearing between the LH2 side and the LOX side, which OTOH have to be purged with pressurized Helium in most engines.

Also, the dual expander can provide pure GH2 and GOX for autogenous pressurization, which as mentioned seems to be the case here (pipe leading both in and out on both sides). I suspect that Blue is aiming to completely eliminate helium on the Blue moon spacecraft. Between this and the fuel cells, it does makes me wonder if they're planning to leapfrog ULA's ACES and go with autogenous pressurization to eliminate helium on their other hydrogen stages as well.

This makes me suspect that one of the BE-5 or BE-6 could be a GOX/GH2 hot gas thruster to be used for all their in-space stages.

TrevorMonty · « **Reply #16 on:** 05/11/2019 02:36 am »

Rik thanks for Scott Manley link.

He did a good job of explaining different expander engines.

One thing he pointed out was difference between EL10 ISP465 and BE7 ISP453. Said it was because of RL10 extra large nozzle which isn't practical for lander.
In theory they could add larger nozzle for OTV and so increase ISP.

Nilof · « **Reply #17 on:** 05/17/2019 12:09 am »

The labels on the mockup seem to make absolutely no sense. They have arrows but they don't seem to indicate flow direction.

Nilof · « **Reply #18 on:** 05/17/2019 12:41 am »

This is what I assume that the actual flows are on H2 side. With phases from liquid to compressible liquid to supercritical to gas.

I'm slightly confused by that pipe of supercritical H2 to the tanks for autogenous pressurization. Feels like a waste of pressure budget to use that instead of GH2, unless you literally want to pressurize fuel tanks above the engine's chamber pressure. Maybe related to throttling down to very low chamber pressures? Or maybe the flow should be reversed, and it's for running in pressure-fed mode during startup?

Nilof · « **Reply #19 on:** 05/17/2019 01:55 am »

OK, now I'm surprised. Neither side is split?

So cycle is basically like attached (closed dual expander with autogenous pressurization), with some extra shenanigans in the connection to the tanks and some extra valves?

That would have the benefit of allowing the engine to be gas/gas, which could generally make it more reliable. But mass flow of oxidizer through the CC walls would be kind of crazy and the design might have a lower size cap than regular expanders.