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Blue Origin - BE-4 Methalox Engine

Discussion in 'SpaceX' started by Grendal, Mar 6, 2017.

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  1. Grendal

    Grendal Active Member

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    #1 Grendal, Mar 6, 2017
    Last edited: Mar 6, 2017
    It looks like Blue Origin has just completed their first BE-4 engine. It is similar, but different from SpaceX's Raptor methalox engine.

    The BE-4 is a ORSC= oxygen rich staged combustion. LOX sent into a preburner then to the combustion chamber so ox rich gas, LOX and LCH4 burned together.

    The Raptor is a FFSC= full flow staged combustion. Both LOX and LCH4 sent to preburners before the combustion chamber which leads to higher chamber pressure and isp.

    The BE-4 is slated to possibly replace the Russian RD-180 used in the Atlas V. The new ULA rocket is called the Vulcan and would use two BE-4s or possibly a couple Aerojet AR-1 engines. The BE-4 remains the primary possibility based on the results of a full scale engine test. Until now there was no full scale engine. So we'll likely see a test of this engine soon and an announcement that ULA will use it soon.

    Twitter

    17039026_10154571748499958_5682981164242526254_o.jpg

    Jeff Bezos (@JeffBezos) | Twitter
    For an image of a test firing of an early smaller test engine. Similar to the images we've seen of the Raptor test firings.
     
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  2. HVM

    HVM Savolainen

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    Size and thrust comparison

    Vac, Thrust in Mega Newtons (MN)

    F-1 7.7 MN
    RS-68 3.6 MN
    Raptor 3.1 MN
    RD-180 2.4 MN
    BE- 4 2.4 MN
    Merlin 1DFT 0.9 MN

    ewsmgIf.png
    RS-68-J2.jpg
    RS-68
    f-1-test-engine_custom-7fad9bdbd976943a29f4a18184812986ed97581f-s800-c85.jpg
    F-1
    RD-180.jpg RD-180
    5472429_orig.jpg
    Merlin
     
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  3. Grendal

    Grendal Active Member

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    Interesting article on ULA using the BE-4. The BE-4 was on the test stand a couple weeks ago. No information on whether it has been fired or not. The article has some interesting information on the testing and development of a rocket engine as well. We know that SpaceX is going through similar things with their Raptor. The comments of the article has a lot of useful information too. One commenter seems to have a good handle on the different strategies between what BO is doing and what SpaceX is doing.

    ULA chief says Blue Origin in driver’s seat for Vulcan engine deal – Spaceflight Now
     
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  4. Grendal

    Grendal Active Member

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    The BE-4 engine had an incident in their testing:

    Blue Origin on Twitter

    So BO had something in their turbopumps and valves RUD.

    From Wiki:
    • Powerpack (rocket engine), the set of turbopumps and valves that provides the fuel-oxidizer mix to the injectors and combustion
      chamber of a liquid rocket engine.
     
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  5. HVM

    HVM Savolainen

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    #5 HVM, May 15, 2017
    Last edited: May 15, 2017
    Normal stuff in rocket business, I hope it didn't take large part of the test stand with it.

    lol.jpg
    ;P
     
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  6. ecarfan

    ecarfan Well-Known Member

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    So the BE-4 will have significantly less thrust than the Raptor, which is a much smaller engine and therefore has a much much higher thrust/weight ratio. It seems the Raptor will then be a much cheaper engine than the BE-4 in terms of thrust/dollar while still being reusable many times (as the BE-4 is also intended to be).

    One other thing: in the comments section of the article @Grendal linked to, Chris Conlon wrote "Raptor is also a Liquid Methane engine while BE-4 is a LNG engine." Meaning that Raptor burns essentially pure CH4 while the BE-4 burns CH4 with a small percentage of C2H6 (ethane) mixed in?

    But I am finding other references saying that the BE-4 uses "liquid methane". Blue Origin's BE-4 Engine

    Are some people using the terms "liquid methane" and "LNG" interchangeably? I thought they were not the same thing.
     
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  7. Grendal

    Grendal Active Member

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    My understanding is they are not quite the same thing. LNG is mostly methane with some other gases mixed in.

    Liquefied natural gas - Wikipedia

    I believe that SpaceX is focused on only methane for a number of reasons with one of the main ones being that they intend to supercool the methane. Another significant reason is for manufacturing the methane on Mars. It would be much more difficult to make LNG on Mars. I suppose it is possible that there are pockets of LNG underground on Mars but, as far as I know, they haven't been discovered.

    As for the Raptor versus BE-4, they are two classes of engines just using somewhat similar fuels. I think it would be similar to comparing the Russian RD-191 to the Merlin. Both of those engines use the same fuel but are different classes of engine.

    I do believe that BO is using LNG for a similar reason as SpaceX which is for reusability reasons.
     
  8. jkn

    jkn Member

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    Raptor has large thrust/size because it has high chamber pressure. High pressure makes it more efficient, but also increases mass. It also increases manufacturing costs, so I guess Raptor has low thrust/dollar value. Cost does not matter, if it is reused many times. Complex high pressure engine is good choice for reusable rocket, not for expandable.

    Diesel engine is more efficient, heavier and expensive than gasoline engine, because of higher pressure.
     
  9. ecarfan

    ecarfan Well-Known Member

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    The BE-4 is also intended to be reusable.

    As to the Raptor thrust/dollar ratio, I would say it is "high" because the Raptor engine can be reused many many times. Reusability means you get a lot of thrust for your dollar over the lifespan of the engine.
     
  10. Grendal

    Grendal Active Member

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    This article is more about the BE-4's competitor in ULA's Vulcan Rocket race:

    AR1 engine clears milestone in step toward ending U.S. reliance on Russian propulsion – Spaceflight Now

    So Aerojet-Rocketdyne's engine for the Vulcan passed a major milestone while BE-4 just had a failure in their testing. This article does a good job of explaining the entire situation and what to expect in the coming years. BE-4 has the lead in the competition and really only has to live up to expectations by passing ULA's tests and milestones.
     
  11. jkn

    jkn Member

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    That would be high (trust*time)/dollar ratio (= impulse/dollar ratio, since force * time = impulse).

    Merlin is also reusable. It is simpler, so its cheaper to manufacture. For high impulse/dollar ratio Merlin is winner. Merlin has also very high trust/mass, because it is relatively simple and low pressure engine.

    High chamber pressure increases sea level ISP, but not best vacuum ISP. For Merlin sea level ISP is 311/348 = 89.4% of vacuum ISP. For Raptor 361/382 = 94.5%

    Numbers from Raptor (rocket engine family) - Wikipedia

    High chamber pressure will make engine smaller, but probably not any lighter. They want 42 engines for ITS, so smaller is better.
     
  12. HVM

    HVM Savolainen

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  13. Grendal

    Grendal Active Member

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    Well, that's good. No explosion this time. Now they just need to keep extending the tests to reach a full burn. I wonder what ULA would consider enough testing to be declared the winner in their competition for Vulcan.

    Ars Technica does a lot of great articles for SpaceX but, in reality, this is just a good American made engine of a new type. Other than that, it has the potential to be a very good American made engine. The BE-4 isn't even in the same ball game as the Raptor has the potential to be. This article just has the feel of those articles that touted the New Shepard as competition for the Falcon 9.

    The reality is that this can potentially be a great rocket engine. Hopefully, it is.
     
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  14. Grendal

    Grendal Active Member

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