Reusable Single Stage to Orbit Concept

[RanulfC]

Hempsell;
I'll agree with your assesment since you've probably had more access to materials than I have. (I still have a 150 page print out listing a total DoD/NASA/AF specific paper search on "plug-nozzle engines" 90+ percent of which I STILL can't access... :::sigh::: )
And I won't disagree about the amount of work needed to get them to work but I WILL point out that so far while the majority of static testing was done with big-bucks and work by NASA and the Air Force, the only folks who are doing actual flight testing is Garvey Aerospace and the University of California.

(Of interesting note is that both GA and UCLB have become less forthcoming on current work on a multi-chamber engine because of NDA's on the technology due to private funding of the research )

Randy

[Jim Davis]

How it is done in SABRE is a commercial secret – Sorry to be evasive.

Mr. Hempsell,

No need to apologize; I quite understand.

At the risk of treading on other commercial secrets I'll ask another question if you'll indulge me.

It appears at first glance that Skylon, with its widely separated engine nacelles, would be difficult to control if there was a thrust imbalance. Specifically, an inlet unstart would subject the spacecraft to a severe yaw, would it not? Can that inadequate looking vertical tail suffice to control Skylon in those conditions? Or does the other inlet unstart to maintain a thrust balance? Would the mission have to be aborted in such a case?  Or does Skylon have such large static margins to make unstarts very unlikely?

Let me add my thanks to all the others for taking the time to post here.

[Hempsell]

How it is done in SABRE is a commercial secret – Sorry to be evasive.

Mr. Hempsell,

No need to apologize; I quite understand.

At the risk of treading on other commercial secrets I'll ask another question if you'll indulge me.

It appears at first glance that Skylon, with its widely separated engine nacelles, would be difficult to control if there was a thrust imbalance. Specifically, an inlet unstart would subject the spacecraft to a severe yaw, would it not? Can that inadequate looking vertical tail suffice to control Skylon in those conditions? Or does the other inlet unstart to maintain a thrust balance? Would the mission have to be aborted in such a case?  Or does Skylon have such large static margins to make unstarts very unlikely?

Let me add my thanks to all the others for taking the time to post here.

The answer is we can cope with an engine out throughout the whole but it does mean a mission abort.

The exact procedure depends on the nature of the failure and when in the ascent it happens.  But the tail fin does play a significant part in the yaw control in many of the cases.  Both it and the forward fin may look intuitively small compared with the body but it is because the main body is abnormally large for the vehicle mass (and hence moments) being about half way to a 1930s airship when empty.

[Hermit]

RanulfC  “Aerospikes work?”
Well yes. They work well on static test stands but once on flying vehicle complications arise like base drag and the interaction of the two supersonic flows they get more complicated. That is not to say they cannot be made to work it is just a lot more complex than simple theory suggests. There are similar complexities with Expansion/Defection nozzles and we may yet still use these, so it is not that we are anti-advanced nozzles .

Actually FLIGHT testing has proven the "complications" aren't as large an issues as was suspected. The test-stand testing didn't address some of those concerns that's WHY they were flight tested. Flight tests have been done with both liquid bi-propellant, mono-propellant,and solid aerospike engines and they do work.

There seem to be quite a few University teams now going for flight tests of aerospikes but I don't remember many that have actually flown.
Could you provide some links regarding the aerospike flight tests.
I'm aware of: http://pdf.aiaa.org/preview/CDReadyMJPC2005_1177/PV2005_3797.pdf and the work of Garvey and CSULB http://pdf.aiaa.org/preview/CDReadyMJPC2004_946/PV2004_3354.pdf.

[Xinvoker]

REL's August update:

During August the first tube manipulation machine was commissioned. Its installation at our manufacturing facility has enabled the assembly of the first production heat exchanger module to begin.
The lack of published news this month is due to internal preparations for significant events, which will be covered in next month's Update.
Be sure to check us out in October!

A teaser!? That's a first i think, i wonder what these events might be.

[RanulfC]

RanulfC  “Aerospikes work?”
Well yes. They work well on static test stands but once on flying vehicle complications arise like base drag and the interaction of the two supersonic flows they get more complicated. That is not to say they cannot be made to work it is just a lot more complex than simple theory suggests. There are similar complexities with Expansion/Defection nozzles and we may yet still use these, so it is not that we are anti-advanced nozzles .

Actually FLIGHT testing has proven the "complications" aren't as large an issues as was suspected. The test-stand testing didn't address some of those concerns that's WHY they were flight tested. Flight tests have been done with both liquid bi-propellant, mono-propellant,and solid aerospike engines and they do work.

There seem to be quite a few University teams now going for flight tests of aerospikes but I don't remember many that have actually flown.
Could you provide some links regarding the aerospike flight tests.
I'm aware of: http://pdf.aiaa.org/preview/CDReadyMJPC2005_1177/PV2005_3797.pdf and the work of Garvey and CSULB http://pdf.aiaa.org/preview/CDReadyMJPC2004_946/PV2004_3354.pdf.

So far the NASA solid-aerospike, NASA X-33 LASR tests, and the Garvey/CSULB flight tests are the only non-DoD stuff I've seen and they are "true" aerospike's rather than the plug-nozzle's and clustered plug-nozzles which are the "duel-use" designs.

I've had issues finding the various data on my usual searches (DTIC/NTRS/etc.) in the last few years as all of my usual "key-words" now bring up very little OTHER than the X-33 linear aerospike work. The DoD/Air Force had gotten as far as building and static testing several different types of flight-hardware pressure-fed, and pump-fed plug-nozzle engines as well as plug-cluster and "true" aerospike engines for various uses.

No actual flight-tests were conducted though and the Air Force had to shut the program down and transfer the data to NASA. Since NASA didn't have funding for it either nothing much has come of the research until the X-33 engine program.
What the USAF DID do is a huge amount of flight configuration wind tunnel work at subsonic, transonic, and medium to high supersonic speeds. But there was a 'gap' in most of the data for low-supersonic speeds and at one point it was reported (during the run-up to the X-33 program) that CFD modelling showed the aformentioned "base-drag" and "supersonic-flow" issues to be pretty daming for the performance of the aerospike design.

From what I read at the time the CFD was actually flawed in that it was based on data from pressure-fed and plug-cluster engines without either the "true" aerospike compression ramp or the "aerodynamic" aerospike of the standard plug-nozzle where turbopump exhaust is directed out the base of the "plug" and aerodynamically produces the elongated "spike" expansion ramp effect. Further CFD's have shown a slight loss of performance around Mach-3 on a nominal rocket flight trajectory due to reduced air-pressure on the outer plume but constriction by the Mach-3 shockwave but that seems to be the only operational issue with the design. (If it actually exists and isn't a "bug" in the CFDs but only actual flight testing to Mach-3 and beyond will tell)

The "duel-use" of a plug-nozzle engine as a heat shield was also well developed during the DoD program even as far as heat soak testing of water, LOx, and LH2 flow systems at reentry temperatures. No money for flight testing though.

Randy

[mlorrey]

So far the NASA solid-aerospike, NASA X-33 LASR tests, and the Garvey/CSULB flight tests are the only non-DoD stuff I've seen and they are "true" aerospike's rather than the plug-nozzle's and clustered plug-nozzles which are the "duel-use" designs.

Um, X-33 LASR was a true aerospike?

[mboeller]

Hi;
I’m rather late to the party so I have only a few comments regarding a few of the discussed designs and ideas.
I personally have 3 favorites regarding SSTO or TSTO concepts, because IMHO you have to learn to crawl before you can walk or even run. But it seems, that always the “feature-creep” seems to demand that the concepts are improved beyond reason so the best concepts, which are for me always the simplest designs, fall out of favor. Therefore my favorite designs are rather simple and straightforward compared to the more elaborate designs favored by the “customers” like NASA and/or the US Air Force:
1) Gomersall’s SSTO concept
2) GD’s Millennium Express
3) LNLL’s Space-Jet concept

1) Gomersall’s SSTO concept is IMHO really good because it had realistic mass properties and technology, therefore it was “suppressed”. The only information about this SSTO which is available is, AFAIK, the document from Scott Lowther. See:
Space-Doc 42 on this page:  http://www.up-ship.com/drawndoc/drawndocspaceshuttle.htm
preview: http://www.up-ship.com/drawndoc/sdoc42ani.gif

2) My next favorite is the Millennium Express from GD which was already mentioned here. The reasons that this concept is one of my favorites are the same as with the Gomersall’s concept: Simple axi-symmetrical structure, base-first reentry, “normal” technology etc. Here you can see a few information’s about the Millennium Express; unfortunately the only ones that I have found:
http://www.spacefuture.com/archive/single_stage_to_orbit_vertical_takeoff_and_landing_concept_technology_challenges.shtml
Also here is a overview of a lot, if not all VTVL SSTO concepts in the world:
http://www.spacefuture.com/archive/history_of_the_phoenix_vtol_ssto_and_recent_developments_in_single_stage_launch_systems.shtml

3) My third favorite is the Space-Jet concept from LNLL which again was already mentioned. Here my reasoning is different. The Space-Jet concept is definitely not simple but has a new twist which makes it IMHO worthwhile. The Space-Jet concept is AFAIK the only TSTO concept which uses small boosters and a large orbiter. All the other TSTO’s I know use a big booster and a rather small orbiter. This makes the Space-Jet concept unique. For me the Space-Jet is the only reasonable way to do it, because the orbiter has to cover by far the largest portion of delta-V to LEO regardless if the staging is at M3 or even M7 and therefore the orbiter has to have the best possible mass properties. A concept which uses a large orbiter like the Space-Jet allows this and improves the changes to succeed with a meaningful payload left.
Unfortunately as with the other concepts not a lot of information is available about this concept. The only real good information was included in the APR N5V5 from Scott Lowther. See:
http://up-ship.com/blog/?p=6010
http://up-ship.com/blog/wp-content/uploads/2010/04/art33ani.jpg

Unrelated to the topic of SSTO/TSTO designs IMHO you should not forget this recently discussed remarkable fuel/oxidizer-combination: Lithium AluminumHexahydride fuel with H2O2 as oxidizer. If the mentioned ISP's are correct (469sec! or 430sec when derived from table 2) then this really dense fuel/oxidizer combination would make SSTOs much easier.
Link:  http://www.sps.aero/Key_ComSpace_Articles/LibTech/LIB-035_Novel_Organometallic_Propellants_for_Hypergolic_Applications.pdf

One final off topic point is the mentioning of the against pressure space suit by RanulfC. IMHO you don’t have to develop such a space suit completely from scratch because IMHO the basic technology was already developed years ago and is even (sort of) available on the market.
The small innovative company prospective concepts had developed a fluid muscle based Anti-G suit nearly 20 years ago already which was then improved and marketed by the company Autoflug; the Libelle Anti-G suit. This Anti-G suit was developed for the german Eurofighter pilots but the german Luftwaffe decided that the suit is not necessary or sufficient. What makes this suit unique is that they use water as fluid muscle to pressurize the Anti-G suit and that the Anti-G effect covers the complete body of the pilot (hands and feet are excluded). IMHO you only have to pressurize the water in the Libelle suit with a different means and then it should work well enough as a basis for an against pressure suit. 
Here are a few links; unfortunately most are in german language:
http://de.wikipedia.org/wiki/Libelle_(Anzug)
http://www.airpower.at/news01/0625_libelle/libelle1.htm  (3 pages, libelle1-3)
http://www.autoflug.net/page.php?page_id=365&menu_id=&ebene=&lang=eng&bereich=p


kind regards
Manfred

[RanulfC]

So far the NASA solid-aerospike, NASA X-33 LASR tests, and the Garvey/CSULB flight tests are the only non-DoD stuff I've seen and they are "true" aerospike's rather than the plug-nozzle's and clustered plug-nozzles which are the "duel-use" designs.

Um, X-33 LASR was a true aerospike?

Yes actually in that it was designed with a "complete" expansion spike (ramp) for the exhaust. Unlike the 'trunicated' plug-nozzle's which use exhaust gases to form an "aerodynamic" spike the "true" aerospikes have a solid surface with which the engine exhaust interacts. In the X-33 engines case each nozzle had a ramp which acted as the "spike" for expansion on one side while ambient air pressure formed the outer surface of the exhaust.

Randy

[Proponent]

1) Gomersall’s SSTO concept is IMHO really good because it had realistic mass properties and technology, therefore it was “suppressed”. The only information about this SSTO which is available is, AFAIK....

Some info is available from NTRS:

http://ntrs.nasa.gov/search.jsp?R=502489&id=1&as=false&or=false&qs=Ntt%3Dgomersall%26Ntk%3Dall%26Ntx%3Dmode%2Bmatchall%26Ns%3DHarvestDate%257c1%26N%3D0

If that link doesn't work, just search for "gomersall".

[RanulfC]

Manfred; Welcome to the topic

Hi;
I’m rather late to the party so I have only a few comments regarding a few of the discussed designs and ideas.
I personally have 3 favorites regarding SSTO or TSTO concepts, because IMHO you have to learn to crawl before you can walk or even run. But it seems, that always the “feature-creep” seems to demand that the concepts are improved beyond reason so the best concepts, which are for me always the simplest designs, fall out of favor. Therefore my favorite designs are rather simple and straightforward compared to the more elaborate designs favored by the “customers” like NASA and/or the US Air Force:
1) Gomersall’s SSTO concept
2) GD’s Millennium Express
3) LNLL’s Space-Jet concept

The Gomersall's SSTO isn't actually "surpressed" as much as there doesn't seem to be a lot avaiable in the first place on the concept. As note by Scott Lowther it is of the same "class" as the Nexus, Bono-related, and Phoenix type VTVL-SSTOs and looks to have come out (1970) about the time Apollo was looking to ramp down so there was probably little if any follow up on the idea.
The GD-Millenium Express is also a good "minimalist" design for an SSTO though it seems to also suffer from the "normal" SSTO issues of not having a lot of margin to play around with during development. Adding boosters is always possible of course but like the "Spacejet" it makes the vehicle a TSTO if not at least a 1.5STO which (much as I like both concepts) doesn't exactly fit the topic unfortunatly

Unrelated to the topic of SSTO/TSTO designs IMHO you should not forget this recently discussed remarkable fuel/oxidizer-combination: Lithium AluminumHexahydride fuel with H2O2 as oxidizer. If the mentioned ISP's are correct (469sec! or 430sec when derived from table 2) then this really dense fuel/oxidizer combination would make SSTOs much easier.
Link:  http://www.sps.aero/Key_ComSpace_Articles/LibTech/LIB-035_Novel_Organometallic_Propellants_for_Hypergolic_Applications.pdf

Thanks I hadn't seen that one before I'll have to read up on it.

One final off topic point is the mentioning of the against pressure space suit by RanulfC. IMHO you don’t have to develop such a space suit completely from scratch because IMHO the basic technology was already developed years ago and is even (sort of) available on the market.

Actually there HAS been a lot of research done on the Mechanical Counter-Pressure Suit, and in fact the original inventor has a company that is taking the concept public. More can be found at "elesticspacesuit.com" if anyone is interested.

Randy

[mboeller]

Some info is available from NTRS:

http://ntrs.nasa.gov/search.jsp?R=502489&id=1&as=false&or=false&qs=Ntt%3Dgomersall%26Ntk%3Dall%26Ntx%3Dmode%2Bmatchall%26Ns%3DHarvestDate%257c1%26N%3D0

If that link doesn't work, just search for "gomersall".

Strange,

When I looked a few years ago on the net, and also specifically at ntrs.nasa.gov the report was not available.

The PDF from ntrs is the same as the PDF from Scott Lowther by the way.

kind regards

Manfred

[mboeller]

The Gomersall's SSTO isn't actually "suppressed" as much as there doesn't seem to be a lot avaiable in the first place on the concept. As note by Scott Lowther it is of the same "class" as the Nexus, Bono-related, and Phoenix type VTVL-SSTOs and looks to have come out (1970) about the time Apollo was looking to ramp down so there was probably little if any follow up on the idea.

the "suppressed" is in brackets for a reason. I was not really serious about the suppression. But others seem to think this proposal was really kind of suppressed :

The vehicle was promoted as a Space Shuttle, and because of the strong opposition within NASA headquarters and the two other principal NASA manned Spaceflight Centers, Marshall and Johnson, the concept was quickly suppressed and Gomersall was assigned to non-launch vehicle-related duties [Ref. personal communication].

source:  http://www.spacefuture.com/archive/history_of_the_phoenix_vtol_ssto_and_recent_developments_in_single_stage_launch_systems.shtml

The GD-Millenium Express is also a good "minimalist" design for an SSTO though it seems to also suffer from the "normal" SSTO issues of not having a lot of margin to play around with during development. Adding boosters is always possible of course but like the "Spacejet" it makes the vehicle a TSTO if not at least a 1.5STO which (much as I like both concepts) doesn't exactly fit the topic unfortunatly

True, but SSTO's are always on the edge of the technology. Therefore, at least for me, it should be mandatory to use a design with the highest possible mass margin, simplest structure and the least demanding systems and environment. This is IMHO always violated as far as I can see.

Thanks I hadn't seen that one before I'll have to read up on it.

I'm really curious about this fuel/oxidizer combo, because it is AFAIK something really new and the quoted performance is simply outstanding, if true.

Actually there HAS been a lot of research done on the Mechanical Counter-Pressure Suit, and in fact the original inventor has a company that is taking the concept public. More can be found at "elesticspacesuit.com" if anyone is interested.

WOW! Thanks for the link. I know that a lot or research was done in the 60th's but I was not aware of the recent developments.


Manfred

[Da5id]

http://www.bbc.co.uk/blogs/thereporters/jonathanamos/2010/09/it-is-one-of-those.shtml

Thought this might be interesting in this thread about Skylon

[93143]

Very interesting.  Apparently the D1 looks like it will have transatlantic ferry range on straight hydrogen.  I wonder if you could increase that by loading some LOX and going semiballistic...  well, obviously you could; it's an SSTO - but it might stress the vehicle too much and wind up counting as one of the 200 "flights" it was designed for...

Anyway, I hope this works...  good to hear the London Economics people think it's such an awesome idea...

I can see this cornering the market for 15 mT and below, while SpaceX expands upwards with their Merlin 2 - the launch cost per kg on a Falcon XX could get fairly close to the expected figures for Skylon, provided the market doesn't suddenly go nuts and start flying Skylons for close to the cost of propellant...

[mlorrey]

Very interesting.  Apparently the D1 looks like it will have transatlantic ferry range on straight hydrogen.  I wonder if you could increase that by loading some LOX and going semiballistic...  well, obviously you could; it's an SSTO - but it might stress the vehicle too much and wind up counting as one of the 200 "flights" it was designed for...

Anyway, I hope this works...  good to hear the London Economics people think it's such an awesome idea...

I can see this cornering the market for 15 mT and below, while SpaceX expands upwards with their Merlin 2 - the launch cost per kg on a Falcon XX could get fairly close to the expected figures for Skylon, provided the market doesn't suddenly go nuts and start flying Skylons for close to the cost of propellant...

Don't worry, British and EU taxes will make up for it.