Author Topic: Blue Origin's BE-7 engine  (Read 78909 times)

Offline Pueo

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Re: Blue Origin's BE-7 engine
« Reply #20 on: 05/17/2019 03:15 pm »
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?

The 10,000 lbs thrust of the engine is below that where a split expander cycle would be needed.

I believe that pipe is to the combustion chamber, not the tanks.  The purpose would be to have a portion of the expanded gases bypass the turbo to allow for lower throttle.

Edit: added diagram
« Last Edit: 05/17/2019 04:14 pm by Pueo »
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Offline Nilof

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Re: Blue Origin's BE-7 engine
« Reply #21 on: 05/17/2019 04:34 pm »
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?

The 10,000 lbs thrust of the engine is below that where a split expander cycle would be needed.

I believe that pipe is to the combustion chamber, not the tanks.  The purpose would be to have a portion of the expanded gases bypass the turbo to allow for lower throttle.

Edit: added diagram

Okay, I get what you're saying and it looks like you're right.

This is a beautifully simple engine. Dual expander with no seals. Bypass valve to throttle.  gas/gas injectors. Not a lot that can go wrong in operation.
For a variable Isp spacecraft running at constant power and constant acceleration, the mass ratio is linear in delta-v.   Δv = ve0(MR-1). Or equivalently: Δv = vef PMF. Also, this is energy-optimal for a fixed delta-v and mass ratio.

Offline Pueo

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Re: Blue Origin's BE-7 engine
« Reply #22 on: 05/17/2019 05:27 pm »
On the other hand if flat plates on the ends of the turbopumps are in fact inlets, that would suggest that there is a split.  This kinda makes sense given there appears to be 2-stages to the oxidizer pump with the lower pressure getting sent to the combustion chamber and the higher to the cooling jacket.  It would also make the indicated directions on the pipes make sense.
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Offline Nilof

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Re: Blue Origin's BE-7 engine
« Reply #23 on: 05/17/2019 09:58 pm »
On the other hand if flat plates on the ends of the turbopumps are in fact inlets, that would suggest that there is a split.  This kinda makes sense given there appears to be 2-stages to the oxidizer pump with the lower pressure getting sent to the combustion chamber and the higher to the cooling jacket.  It would also make the indicated directions on the pipes make sense.

Right. I thought there was a split at first from the turbopump shape, until I started to trace out the pipes and noted that they both only had four connections.
For a variable Isp spacecraft running at constant power and constant acceleration, the mass ratio is linear in delta-v.   Δv = ve0(MR-1). Or equivalently: Δv = vef PMF. Also, this is energy-optimal for a fixed delta-v and mass ratio.

Offline b0objunior

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Re: Blue Origin's BE-7 engine
« Reply #24 on: 05/17/2019 10:20 pm »
Question, from what we know of the BE-7, does it seems like a good transfer vehicle engine?

Offline Khadgars

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Re: Blue Origin's BE-7 engine
« Reply #25 on: 05/17/2019 10:33 pm »
Not gonna lie, I'm enjoying this thread immensely even though I can only vaguely follow it  ;D
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Offline TrevorMonty

Re: Blue Origin's BE-7 engine
« Reply #26 on: 05/17/2019 11:32 pm »
The BE7 would make great US engine for New Shepard smallsat launcher. Jeff did mention this idea in passing. While it would be well within Blues capabilities, I'd be surprised if they do it given how many other projects they have ongo.



Offline Klebiano

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Re: Blue Origin's BE-7 engine
« Reply #27 on: 06/02/2019 04:24 am »
The valves on this engine looks a lot like a stepper motor with NEMA type enclosure, anyone knows more about these valves?

Offline Robotbeat

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Re: Blue Origin's BE-7 engine
« Reply #28 on: 06/02/2019 04:27 am »
The valves on this engine looks a lot like a stepper motor with NEMA type enclosure, anyone knows more about these valves?
They could be servo motors with a NEMA like casing.

I would bet those are either stand-ins for the real thing or it's a relatively crude prototype. Those kinds of casings aren't terribly flightweight. And that matters a LOT for a lunar vehicle.
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Offline b0objunior

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Re: Blue Origin's BE-7 engine
« Reply #29 on: 06/02/2019 04:32 am »
The valves on this engine looks a lot like a stepper motor with NEMA type enclosure, anyone knows more about these valves?
They could be servo motors with a NEMA like casing.

I would bet those are either stand-ins for the real thing or it's a relatively crude prototype. Those kinds of casings aren't terribly flightweight. And that matters a LOT for a lunar vehicle.
How much mass are they?

Offline ZachF

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Re: Blue Origin's BE-7 engine
« Reply #30 on: 06/02/2019 04:38 pm »
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?

The 10,000 lbs thrust of the engine is below that where a split expander cycle would be needed.

I believe that pipe is to the combustion chamber, not the tanks.  The purpose would be to have a portion of the expanded gases bypass the turbo to allow for lower throttle.

Edit: added diagram

Full Flow expander cycle...?  ;)
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Offline Klebiano

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Re: Blue Origin's BE-7 engine
« Reply #31 on: 06/04/2019 02:55 am »
The valves on this engine looks a lot like a stepper motor with NEMA type enclosure, anyone knows more about these valves?
They could be servo motors with a NEMA like casing.

I would bet those are either stand-ins for the real thing or it's a relatively crude prototype. Those kinds of casings aren't terribly flightweight. And that matters a LOT for a lunar vehicle.
How much mass are they?

Not much, for example, a NEMA 34 can weight 5kg, but I think that the problem is not the weight, it's the environment that these motors have to withstand.

Offline Robotbeat

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Re: Blue Origin's BE-7 engine
« Reply #32 on: 06/04/2019 03:33 am »
The valves on this engine looks a lot like a stepper motor with NEMA type enclosure, anyone knows more about these valves?
They could be servo motors with a NEMA like casing.

I would bet those are either stand-ins for the real thing or it's a relatively crude prototype. Those kinds of casings aren't terribly flightweight. And that matters a LOT for a lunar vehicle.
How much mass are they?

Not much, for example, a NEMA 34 can weight 5kg, but I think that the problem is not the weight, it's the environment that these motors have to withstand.
There are 6 of them, so 30kg. That makes a significant different to the engine’s thrust to weight. I suspect a different form factor would halve the mass; I think these are just for the prototype.
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Offline Navier–Stokes

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Offline TrevorMonty

Re: Blue Origin's BE-7 engine
« Reply #34 on: 06/20/2019 11:15 am »
35sec is impressive for 1st firing.

Offline ZChris13

Re: Blue Origin's BE-7 engine
« Reply #35 on: 06/20/2019 01:36 pm »
are they using TEA-TEB (or equivalent) for ignition or was it burning combustion chamber rich there?

Offline Navier–Stokes

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Re: Blue Origin's BE-7 engine
« Reply #36 on: 06/20/2019 02:20 pm »
are they using TEA-TEB (or equivalent) for ignition or was it burning combustion chamber rich there?
It's the ignition system:
First hotfire of our #BE7 lunar landing engine just yesterday at Marshall Space Flight Center. Data looks great and hardware is in perfect condition. What you’re seeing at the bottom is a water cooling system and the green flame is the ignition system. The engine plume you see is very clear because the fuel is hydrogen. Test went full planned duration – 35 seconds. Kudos to the whole @BlueOrigin team and grateful to @NASA_Marshall for all the help!
Emphasis mine

Offline Gliderflyer

Re: Blue Origin's BE-7 engine
« Reply #37 on: 06/21/2019 12:02 am »
35sec is impressive for 1st firing.
And somewhat surprising given their somewhat cautious and methodical nature. For a first engine run, you usually want to run it for a second or two. It is usually difficult to slag an engine in the first couple seconds if something is wrong (it can run in "heatsink mode"), but it also gives you enough data to see if the engine is trending towards steady state or towards eating itself.

There also seems to be a howl during the engine run. It could always be an audio artifact or some component of the test hardware (that is somehow louder than a rocket engine), but it sounds a lot like high-frequency combustion instability. What little you can see of the plume seems to dance around a bit, which also points to instability. It ran for 35 seconds, so it isn't the "instant engine destruction" flavor of instability, but I doubt it is desirable.
I tried it at home

Re: Blue Origin's BE-7 engine
« Reply #38 on: 07/19/2019 12:13 am »
Pretty impressive! Now if only they would share some footage...

https://twitter.com/jeff_foust/status/1152007076333277184?s=20
« Last Edit: 07/19/2019 12:21 am by TG Revv »
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Offline b0objunior

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Re: Blue Origin's BE-7 engine
« Reply #39 on: 07/19/2019 12:41 am »
Pretty impressive! Now if only they would share some footage...

https://twitter.com/jeff_foust/status/1152007076333277184?s=20
Moving fast, great! Hope to see a video of that!

Tags: be-7 Blue Origin 
 

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