Author Topic: The Reaction Engines Skylon/SABRE Master Thread (6)  (Read 294516 times)

Offline john smith 19

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Re: The Reaction Engines Skylon/SABRE Master Thread (6)
« Reply #800 on: 01/04/2018 08:25 AM »
I'm not sure if this has been posted before.

It's a 2016 presentation by Robert Bond to Imperial College in March 2016.

Pages 25 and 32 are especially interesting.

Page 25 shows SABRE 4 cycle performance compared to other engine systems. Maximum T/W is around M2 at 14:1, although it still looks around 10 at M3 (the SR71 package was around 2.75:1 at this point), droppoing to about 6 at M5.

Max specific impulse is about 6000 secs at M1.5, dropping to 4000 at M3 and 3000 at M5.

Zero speed values are about 7.5:1 and >4500secs.

Page 32 gives an actual precooler test run data set.

https://www.friendsofimperial.org.uk/Media/Slides/201602_SABRE_Engine.pdf

I think the SABRE 4 cycle is the baseline for future work.
« Last Edit: 01/05/2018 10:23 AM by john smith 19 »
BFS. The worlds first Methane fueled FFORSC engined CFRP structured A380 sized aerospaceplane tail sitter capable of flying in Earth and Mars atmospheres. BFR. The worlds biggest Methane fueled FFORSC engined CFRP structured booster for BFS. First flight to Mars by end of 2022. Forward looking statements. T&C apply. Believe no one. Run your own numbers. So, you are going to Mars to start a better life? Picture it in your mind. Now say what it is out loud.

Offline CrewtaiL

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Re: The Reaction Engines Skylon/SABRE Master Thread (6)
« Reply #801 on: 01/05/2018 05:04 PM »
The ISP vs Mach graphs in the above doc. aren't accurate, I don't think. Seen others which show efficiency at M5 to be significantly greater (than 3,000)


Found an interesting review of UK space facilities. RE need a 2MN rocket test facility and hypersonic wind tunnels.

https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/665552/UK_Space_Facilities_Review_December_2017.pdf

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Re: The Reaction Engines Skylon/SABRE Master Thread (6)
« Reply #802 on: 01/05/2018 05:18 PM »
Where have you seen graphs claiming the ISP is significantly better than what REL says it is? Based on what?

Offline CrewtaiL

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Re: The Reaction Engines Skylon/SABRE Master Thread (6)
« Reply #803 on: 01/08/2018 03:47 PM »
Where have you seen graphs claiming the ISP is significantly better than what REL says it is? Based on what?

Can't locate the graphs right now but they only differ (from those posted) by the SABRE curve being above the ramjet one. IIRC, ISP at M4.5 was ~ 4,000
« Last Edit: 01/08/2018 03:51 PM by CrewtaiL »

Offline Asteroza

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Re: The Reaction Engines Skylon/SABRE Master Thread (6)
« Reply #804 on: 01/09/2018 07:00 AM »
Maybe a SABRE 3/4 cycle difference perhaps?

Offline CrewtaiL

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Re: The Reaction Engines Skylon/SABRE Master Thread (6)
« Reply #805 on: 01/09/2018 01:16 PM »
Maybe a SABRE 3/4 cycle difference perhaps?

No, I don't think so. One of the graphs is badly drawn; if I could just find it again.


For now, found this:

https://www.nas.nasa.gov/assets/pdf/papers/Mehta_Unmeel_Skylon_2015.pdf



Offline JCRM

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Re: The Reaction Engines Skylon/SABRE Master Thread (6)
« Reply #806 on: 01/09/2018 01:54 PM »
That graph show significantly lower ISP than the 4000-9000 promised for the SABRE 4 in the Skylon Users Manual, and I too remember the curve being above the ramjet line. I hope it is just a badly drawn graph - but it may be a a result of the work done for REL by Bayern-Chemie on intakes and ramjets.

I'm not sure if this has been posted before.
Nice find, I've not seen it before. The part I found particularly encouraging is that they have managed to recreate the manufacturing process for the skin.
« Last Edit: 01/09/2018 02:05 PM by JCRM »

Offline john smith 19

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Re: The Reaction Engines Skylon/SABRE Master Thread (6)
« Reply #807 on: 01/09/2018 03:56 PM »
That graph show significantly lower ISP than the 4000-9000 promised for the SABRE 4 in the Skylon Users Manual, and I too remember the curve being above the ramjet line. I hope it is just a badly drawn graph - but it may be a a result of the work done for REL by Bayern-Chemie on intakes and ramjets.
Well "ramjets" in the context of the graph will be other ramjets used on other vehicles, usually for missiles like BOMARC, Bloodhound or Thunderbird, not the "spill ramjets" on SABRE. IIRC when Mark Hempsell was working for REL he posted they were well within the SoA and contributed (indirectly) around 300-400m/s 

The air intakes were designed to be axisymetric (presumably to be fairly easy to analyze) but they do have to operate have a wide Mach range. In principle the data from that can feed (more or less) directly into the software sheduling the inlet cone positions.

Quote from: JCRM
I'm not sure if this has been posted before.
Nice find, I've not seen it before. The part I found particularly encouraging is that they have managed to recreate the manufacturing process for the skin.
Thank you. It didn't look familiar to me.

I think the fact it was for the "Friends of Imperial College" may explain why they went into more detail than usual on their efforts to recreate the HOTOL skin material. That seems to have been one of the successful parts of the project. In one of his lectures Alan Bond mentions it seems to be nearly perfect for making spaceplane skins. 

Note the skin is only part of it. It has to operate with a "mounting system" and a "joining system." The latter lets you make airtight joints between the panels, preventing plasma entry into the fuselage. The former allows the skin expand while keeping it in the same relative position to the airframe.

This is based on the use of "hairpin rivets," and beyond being part of the X20 Dyna Soar baseline I've never seem them used anywhere else.  :( Since it's been mentioned that Skylon needs 50 000 struts I'd guess it will need a substantially greater number of these rivets, which have to be easy to make and consistent in quality.

That said while 50 000 struts sounds a huge number an automatic machine that placed 1 strut a minute (running 24/7) could build the whole airframe in 35 days, provided the strut supply could be maintained.
BFS. The worlds first Methane fueled FFORSC engined CFRP structured A380 sized aerospaceplane tail sitter capable of flying in Earth and Mars atmospheres. BFR. The worlds biggest Methane fueled FFORSC engined CFRP structured booster for BFS. First flight to Mars by end of 2022. Forward looking statements. T&C apply. Believe no one. Run your own numbers. So, you are going to Mars to start a better life? Picture it in your mind. Now say what it is out loud.

Offline JCRM

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Re: The Reaction Engines Skylon/SABRE Master Thread (6)
« Reply #808 on: 01/11/2018 08:46 AM »
We have seen the graph before, in a different presentation in 2016

That graph show significantly lower ISP than the 4000-9000 promised for the SABRE 4 in the Skylon Users Manual, and I too remember the curve being above the ramjet line. I hope it is just a badly drawn graph - but it may be a a result of the work done for REL by Bayern-Chemie on intakes and ramjets.
Well "ramjets" in the context of the graph will be other ramjets used on other vehicles, usually for missiles like BOMARC, Bloodhound or Thunderbird, not the "spill ramjets" on SABRE.
I meant the SABRE curve may have been adjusted downward in light of the work Beyern-Chemie has done for REL, not that the Ramjet curve had been improved, or that the ramjet curve on the graph represented the performance of the SABRE ramjets.

Quote from: john smith 19
IIRC when Mark Hempsell was working for REL he posted they were well within the SoA and contributed (indirectly) around 300-400m/s
SABRE 2, 4a or 4b?

I think the fact it was for the "Friends of Imperial College" may explain why they went into more detail than usual on their efforts to recreate the HOTOL skin material. That seems to have been one of the successful parts of the project. In one of his lectures Alan Bond mentions it seems to be nearly perfect for making spaceplane skins. 
I thought nickel alloy shingle was specified for HOTOL by BAe. Bond was exposed to System2 during his work at the fusion reactor, and specified if for Skylon when the REL team designed a concept vehicle for SABRE  (it wouldn't be noteworthy that a skin designed for a spaceplane was nearly perfect for spaceplanes)

Offline CrewtaiL

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Re: The Reaction Engines Skylon/SABRE Master Thread (6)
« Reply #809 on: 01/12/2018 01:33 PM »
Does anyone know why the cooling rate has apparently reduced from one one-hundredth of a second to one one-twentieth?


Graph I alluded to can be seen (not very clearly) at min. 28 of the following presentation:

« Last Edit: 01/12/2018 03:48 PM by CrewtaiL »

Offline john smith 19

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Re: The Reaction Engines Skylon/SABRE Master Thread (6)
« Reply #810 on: 01/12/2018 06:43 PM »
Does anyone know why the cooling rate has apparently reduced from one one-hundredth of a second to one one-twentieth?


Graph I alluded to can be seen (not very clearly) at min. 28 of the following presentation:
Part of the difference between SABRE 4 and SABRE 3 cycles is a reduction in the cooling level planned as the design pivots to a dual chamber engine with shared turbomachinery rather than a single system. This means you can optimize rocket and air breathing combustion chamber pressures separately. Lower AB combustion chamber pressures mean it's even more gas turbine like (SoA GT pressure ratios are <30:1, while SABRE 3 needed it closer to the rocket chamber pressure, about 100-120:1)

That substantially reduces cooling needs and IIRC REL have said it no longer needs an active frost control system, but obviously needs a somewhat heavier engine. The trades indicate what you lose on engine mass growth (2 separate chambers) you gain on needing less LH2 (and more importantly the structure to carry it). You also (in principal) lower the technical risk as you move to lower pressures.
BFS. The worlds first Methane fueled FFORSC engined CFRP structured A380 sized aerospaceplane tail sitter capable of flying in Earth and Mars atmospheres. BFR. The worlds biggest Methane fueled FFORSC engined CFRP structured booster for BFS. First flight to Mars by end of 2022. Forward looking statements. T&C apply. Believe no one. Run your own numbers. So, you are going to Mars to start a better life? Picture it in your mind. Now say what it is out loud.

Offline JCRM

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Re: The Reaction Engines Skylon/SABRE Master Thread (6)
« Reply #811 on: 01/23/2018 08:57 AM »
Given the excitement in the UK construction industry last week, does anyone know who's building TF1?

I'm pleased to see live camera feed is from a company that specialises in project time-lapse imagery.

The construction team in Colorado is having much nicer weather...

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Re: The Reaction Engines Skylon/SABRE Master Thread (6)
« Reply #812 on: 01/23/2018 11:53 AM »
Mark Wood is giving a presentation on SABRE to the IET on 23rd March. With any luck I'll be able to leg it across London in time to make it, and there's usually a generous Q&A session afterwards if there are any burning questions people want answered.

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Re: The Reaction Engines Skylon/SABRE Master Thread (6)
« Reply #813 on: 02/02/2018 08:36 AM »

Offline CrewtaiL

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Re: The Reaction Engines Skylon/SABRE Master Thread (6)
« Reply #815 on: 02/09/2018 01:01 PM »

Offline john smith 19

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Re: The Reaction Engines Skylon/SABRE Master Thread (6)
« Reply #816 on: 02/10/2018 11:31 AM »
https://twitter.com/ReactionEngines/status/961962101295210497
It certainly looks like things are moving. This is the assembly building for the test site and it looks close to weather tight, which should allow them to begin fit out. It would be exciting to think they could begin assembly of the first stage of the SABRE test engine before the test stand/control building is complete.   
« Last Edit: 02/11/2018 11:01 AM by john smith 19 »
BFS. The worlds first Methane fueled FFORSC engined CFRP structured A380 sized aerospaceplane tail sitter capable of flying in Earth and Mars atmospheres. BFR. The worlds biggest Methane fueled FFORSC engined CFRP structured booster for BFS. First flight to Mars by end of 2022. Forward looking statements. T&C apply. Believe no one. Run your own numbers. So, you are going to Mars to start a better life? Picture it in your mind. Now say what it is out loud.

Offline JCRM

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Re: The Reaction Engines Skylon/SABRE Master Thread (6)
« Reply #817 on: 02/14/2018 09:55 AM »
https://twitter.com/ReactionEngines/status/961962101295210497
It certainly looks like things are moving. This is the assembly building for the test site and it looks close to weather tight, which should allow them to begin fit out. It would be exciting to think they could begin assembly of the first stage of the SABRE test engine before the test stand/control building is complete.
It's not the "assembly building," it's the "assembly building, workshops, offices and control room."

From memory, the first of the engine tests, the helium loop, was timetabled to occur before the test stand is complete.

Offline IRobot

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Re: The Reaction Engines Skylon/SABRE Master Thread (6)
« Reply #818 on: 02/14/2018 10:14 AM »
With recent SpaceX's successes and competition from BO, I think either Skylon is scaled up for larger payloads  or this whole program will not generate a space plane, it will be for military and perhaps civil aircrafts.

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Re: The Reaction Engines Skylon/SABRE Master Thread (6)
« Reply #819 on: 02/14/2018 06:54 PM »
With recent SpaceX's successes and competition from BO, I think either Skylon is scaled up for larger payloads  or this whole program will not generate a space plane, it will be for military and perhaps civil aircrafts.

...Or it will be used for nothing.

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