http://selenianboondocks.com/2010/06/ssto-ntr-bad/
Maybe the SSTO idea should be discarded altogether...
Maybe the SSTO idea should be discarded altogether...
AHC/PC: SSTO - "Single Stage to Orbit" vehicle
- Thread starter Tal Shiar
- Start date
Heresy! String up the non-believer! He, actually I and Kirk went a few rounds on NSF over NTR, but yes, it helps if you CAN but if you design to the 'either/or' option, (it either works or it doesn't) then you're set up for failure should things not go exactly as planned. (Hint: they never do)
The basic "idea" isn't bad per-se, it's based after all on trying to mirror all other forms of transport we are used to, the thing is space travel is simply NOT any other form of transport we're used to and it helps if you start from that position.
Again, we can 'get' there but we need to loosen the constraints a bit to allow "almost" and "assisted" SSTO's or even starting out as a TSTO.
So does my scenerio of 'getting' there make sense to you folks?
Randy
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I don't understand what you're saying, could you please clarify more to the non-rocket scientist.
And is a NTR SSTO a good idea, according to you?
Windows95 wrote:
ROMBUS, (no "H" as it stands for "Reusable Orbital Module-Booster & Utility Shuttle"
) and yes in fact it DID need rather complicated engines as the proposed engines were both high pressure and a very high O/F (oxidizer/fuel ratio) pretty much on-par with the effort needed to design and build the Space Shuttle Main Engine. (Some of Bono's later designs actually used SSMEs as engines but noted the difference in performance due not using his preferred engines/combustion chambers)
Also keep in mind that having 'drop-tanks' is precluded by the OP's criteria, (no "dropped" parts) though ROMBUS could still deliver 'some' of its payload capacity as an SSTO without the drop tanks. (Depending on who's figures you use of the initial 990Klbs of payload a non-drop-tank ROMBUS might be able to loft as much as 90Klbs or as little as 20Klbs but a the per-flight cost very similar to the 'full-up' ROMBUS as not using the drop tanks doesn't really save as much as you might think) Further the operations costs of the ROMBUS aren't as 'cheap' as Bono suggested considering you need a whole new pad and support system, (ROMBUS had to be launched from a pad over a water filled basin to direct and deaden the noise levels as ground reflections would have damaged the LV during lift off) along with an expansion of the Kennedy launch complex.
Windows95 wrote:
First and foremost the "Heresy!" and "String up the non-believer!" comments are jokes so please take them as such
In general the idea behind "SSTO" is simply that in no other form of economic transportation that we use on Earth are multiple 'stages' of a vehicle used to move people or cargo where parts of the transport are dropped off during the trip. So the 'ideal' is seen of the "SSTO" being THE most obvious and practical means of achieving robust, economical space transport BECAUSE that's what we use on Earth. The argument is that despite the "obvious" short-comings of SSTO, (low-payload and unknown costs and complications of operations) once SSTO is in use it alone will cause a rapid drop in access prices and all that entails. The problem with the argument is that it has a very large number of 'assumptions' attached that if any one of them do not come about fully then the presuppositions and therefore the outcomes will be wrong.
One of the things I've been pointing out is that while being able to deliver a small payload of 10Klbs or less to LEO "might" prove out the concept of SSTO in general it will be very unlikely to significantly impact the costs of access or economics of space flight because there is in fact no 'market' for 10Klbs to LEO. The other is the assumption that a single-stage SSTO will of course cost vastly less to 'process' and turn around and will have a vastly higher 'flight-rate' capability than any multistage vehicle which is totally unproven. Especially as we're talking a vehicle that flies from zero-to-orbital speed-and-back again for which we've only had limited experience with vehicles that have NOT shown this to be true.
It is likely that even when designed for easy turn-around, (and that in and of itself predicates a number of design compromises to allow such operations which will end up effecting other aspects of the vehicle both operationally and design wise) such a complex and marginal vehicle will have a turnaround time measured in at best days to weeks which is nowhere near the 'assumed' turnaround time of hours at the very most.
Having said all this of course the plain fact is we COULD build an SSTO vehicle, probably even a reusable SSTO vehicle, with known technology and 'prove' it could be done. But what utility would such a vehicle have? As Gary Hudson, (of Phoenix and ROTON fame) pointed out while the ability to orbit and return "two guys and a ham sandwich" in an SSTO would be record and headline making to gain actual utility you need to push the payload above about 10Klbs to LEO at least AND have a viable market to use that capability. When you have 'competition' that can probably match your flight rate and still deliver anywhere from 5 to 10 times your payload mass per flight your 'utility' and 'economics' case becomes very, very weak.
The answer very much depends on the design and utility of the NTR SSTO Several of the advanced NTR designs as well as the later models of the NERVA could have been used for viable "NTR SSTO" designs but they would not have been 'pure' SSTO's because they would for the most part need 'assists' to reach optimum altitude and speed where the NTR operated the best. One thing Kirk and I went around and around on was the idea that the NTR would not be an integral part of the vehicle but would be removed on-orbit and stored, (to allow it to "cool" both thermally and radioactively) because coming back with 'hot' reactor just isn't the best way to go. Placing the NTR into a specifically designed 'propulsion' module that could if needed be jettisoned and recovered separately while it adds mass and complexity to the system is a very obvious safety and support addition but is very counter-intuitive to the ideas of "minimum-mass" and "light weight' design that is the basis for "SSTO" design.
I think it's quite possible to have a "good" NTR-SSTO or near-SSTO but like so many 'good' ideas is requires an extensive on-orbit infrastructure and organization that is currently lacking and unlikely to be implemented due to the 'way' we currently do space travel.
Fscott wrote:
The Titan-II first stage is one of the often quoted 'theoretical' SSTO's out there but really it's probably not actually possible to build an SSTO from one. The velocity and aero-loading of such a vehicle would probably tear it apart long before it reached orbit. Even so the "possible total delta-v" was around something like averaged 9400 m/sec-ish whereas around 9200 m/sec (including drag and gravity losses)at least was required for a stable 'orbit' in LEO. And this is with no payload, fairing or even a guidance system so... But with no ability to throttle the engines and taking into account the 'lightness' of the aero-frame it's very unlikely it would NOT tear itself apart long before reaching orbit. Similar arguments have been made for the Black Arrow stage 1, Saturn V second stage the S-II, Saturn-V stage 1 the S-1C, and Energia core stage as possible expendable SSTO vehicles mostly based on the stage mass-fraction. Again this is 'in-theory' (because the basic 'math' says it might) but not taking into account the needed additional hardware or systems needed to make orbit which reduce the already marginal payload.
Similarly I've read that the latest Falcon-9 booster stage 'could' ("in theory") make LEO without any payload as an SSTO, but it would not survive (or even have the propellant) to make it back down again. You CAN actually get SSTO performance out of non-LH2/LOX vehicles as many have been proposed over the years as density has some advantages over those 'high-isp' propellants as shown with RP1/LOX and even H2O2/Kerosene concepts over the years but you're payload is often marginal at best. (Often less than 2,000lbs to LEO)
And you still have the problem that you need some sort of on-orbit infrastructure to both utilize and base the SSTO payload delivered on. And it has to be either 'dirt-cheap' (which even an 'expendable SSTO' design is debatable, see the Aquarius Expendable SSTO design: https://en.wikipedia.org/wiki/Aquarius_(rocket)) to manufacture and operate OR it has to be reusable AND dirt cheap to manufacture and operate.
There's a 'theory' that no one has done SSTO because of organizational and psychological reasons rather than practical or physical reasons. (G. Harry Stine and his book "Half Way to Anywhere" https://www.amazon.com/Halfway-Anywhere-Achieving-Americas-Destiny/dp/0871318059, uses this as a basis for 'why' SSTO keeps 'failing' for example) Trying to lay the "blame" for why no one is 'doing' SSTO on Air Force and NASA institutional and "not-invented-here" arguments but ignoring that almost any other nation can "do the math" the same as anyone in the US and the fact is the 'numbers' don't work out at well as advocates tend to think they do. Especially with the OTL lack of on-orbit infrastructure and lack of LEO servicing needs. You HAVE had several companies and nations do preliminary work on various SSTO concepts and programs, from ARCA's latest 'concept' vehicle, (Haas-2, http://www.arcaspace.com/en/haas2c.htm, https://newatlas.com/single-stage-rocket/48710/) using H2O2/Kerosene to put around 220lb into LEO to Japan's "RTV" program, (a subscale DC-X) to Indian concepts, (again mostly 'sub-scale' test articles) and the British Skylon concept, and others which continue to pop up on regular basis It is quite clear the onus in on the proposer not the lack of 'support' from the "main stream" aerospace industry.
ARCA for example is at least straight forward noting the 'advantage' of their vehicle is it "can be refueled on-orbit" eliminating the need for an upper stage, (thus requiring the capability exists on-orbit to do so) although they repeat the over-used justification that the SSTO has 'less parts' and is therefore more reliable where the SSTO requires very low margins to work so it is arguable that though 'fewer' the parts are in fact 'cheaper' or more reliable. The thing is the 'costs' are still not that much less than 'normal' (and this is an expendable vehicle keep in mind) with payload costs still over $4,000 dollars per pound. (And as of yet no test flight or test for that matter)
So it is reasonable to assume that there might be some fundemental issues with the concept. That's not to say it can't work, after all the "math" does in fact work out, it is more likely the 'assumptions' are flawed instead.
Randy
ROMBUS, (no "H" as it stands for "Reusable Orbital Module-Booster & Utility Shuttle"
) and yes in fact it DID need rather complicated engines as the proposed engines were both high pressure and a very high O/F (oxidizer/fuel ratio) pretty much on-par with the effort needed to design and build the Space Shuttle Main Engine. (Some of Bono's later designs actually used SSMEs as engines but noted the difference in performance due not using his preferred engines/combustion chambers)Also keep in mind that having 'drop-tanks' is precluded by the OP's criteria, (no "dropped" parts) though ROMBUS could still deliver 'some' of its payload capacity as an SSTO without the drop tanks. (Depending on who's figures you use of the initial 990Klbs of payload a non-drop-tank ROMBUS might be able to loft as much as 90Klbs or as little as 20Klbs but a the per-flight cost very similar to the 'full-up' ROMBUS as not using the drop tanks doesn't really save as much as you might think) Further the operations costs of the ROMBUS aren't as 'cheap' as Bono suggested considering you need a whole new pad and support system, (ROMBUS had to be launched from a pad over a water filled basin to direct and deaden the noise levels as ground reflections would have damaged the LV during lift off) along with an expansion of the Kennedy launch complex.
Windows95 wrote:
First and foremost the "Heresy!" and "String up the non-believer!" comments are jokes so please take them as such
In general the idea behind "SSTO" is simply that in no other form of economic transportation that we use on Earth are multiple 'stages' of a vehicle used to move people or cargo where parts of the transport are dropped off during the trip. So the 'ideal' is seen of the "SSTO" being THE most obvious and practical means of achieving robust, economical space transport BECAUSE that's what we use on Earth. The argument is that despite the "obvious" short-comings of SSTO, (low-payload and unknown costs and complications of operations) once SSTO is in use it alone will cause a rapid drop in access prices and all that entails. The problem with the argument is that it has a very large number of 'assumptions' attached that if any one of them do not come about fully then the presuppositions and therefore the outcomes will be wrong.
One of the things I've been pointing out is that while being able to deliver a small payload of 10Klbs or less to LEO "might" prove out the concept of SSTO in general it will be very unlikely to significantly impact the costs of access or economics of space flight because there is in fact no 'market' for 10Klbs to LEO. The other is the assumption that a single-stage SSTO will of course cost vastly less to 'process' and turn around and will have a vastly higher 'flight-rate' capability than any multistage vehicle which is totally unproven. Especially as we're talking a vehicle that flies from zero-to-orbital speed-and-back again for which we've only had limited experience with vehicles that have NOT shown this to be true.
It is likely that even when designed for easy turn-around, (and that in and of itself predicates a number of design compromises to allow such operations which will end up effecting other aspects of the vehicle both operationally and design wise) such a complex and marginal vehicle will have a turnaround time measured in at best days to weeks which is nowhere near the 'assumed' turnaround time of hours at the very most.
Having said all this of course the plain fact is we COULD build an SSTO vehicle, probably even a reusable SSTO vehicle, with known technology and 'prove' it could be done. But what utility would such a vehicle have? As Gary Hudson, (of Phoenix and ROTON fame) pointed out while the ability to orbit and return "two guys and a ham sandwich" in an SSTO would be record and headline making to gain actual utility you need to push the payload above about 10Klbs to LEO at least AND have a viable market to use that capability. When you have 'competition' that can probably match your flight rate and still deliver anywhere from 5 to 10 times your payload mass per flight your 'utility' and 'economics' case becomes very, very weak.
The answer very much depends on the design and utility of the NTR SSTO
Several of the advanced NTR designs as well as the later models of the NERVA could have been used for viable "NTR SSTO" designs but they would not have been 'pure' SSTO's because they would for the most part need 'assists' to reach optimum altitude and speed where the NTR operated the best. One thing Kirk and I went around and around on was the idea that the NTR would not be an integral part of the vehicle but would be removed on-orbit and stored, (to allow it to "cool" both thermally and radioactively) because coming back with 'hot' reactor just isn't the best way to go. Placing the NTR into a specifically designed 'propulsion' module that could if needed be jettisoned and recovered separately while it adds mass and complexity to the system is a very obvious safety and support addition but is very counter-intuitive to the ideas of "minimum-mass" and "light weight' design that is the basis for "SSTO" design.I think it's quite possible to have a "good" NTR-SSTO or near-SSTO but like so many 'good' ideas is requires an extensive on-orbit infrastructure and organization that is currently lacking and unlikely to be implemented due to the 'way' we currently do space travel.
Fscott wrote:
The Titan-II first stage is one of the often quoted 'theoretical' SSTO's out there but really it's probably not actually possible to build an SSTO from one. The velocity and aero-loading of such a vehicle would probably tear it apart long before it reached orbit. Even so the "possible total delta-v" was around something like averaged 9400 m/sec-ish whereas around 9200 m/sec (including drag and gravity losses)at least was required for a stable 'orbit' in LEO. And this is with no payload, fairing or even a guidance system so... But with no ability to throttle the engines and taking into account the 'lightness' of the aero-frame it's very unlikely it would NOT tear itself apart long before reaching orbit. Similar arguments have been made for the Black Arrow stage 1, Saturn V second stage the S-II, Saturn-V stage 1 the S-1C, and Energia core stage as possible expendable SSTO vehicles mostly based on the stage mass-fraction. Again this is 'in-theory' (because the basic 'math' says it might) but not taking into account the needed additional hardware or systems needed to make orbit which reduce the already marginal payload.
Similarly I've read that the latest Falcon-9 booster stage 'could' ("in theory") make LEO without any payload as an SSTO, but it would not survive (or even have the propellant) to make it back down again. You CAN actually get SSTO performance out of non-LH2/LOX vehicles as many have been proposed over the years as density has some advantages over those 'high-isp' propellants as shown with RP1/LOX and even H2O2/Kerosene concepts over the years but you're payload is often marginal at best. (Often less than 2,000lbs to LEO)
And you still have the problem that you need some sort of on-orbit infrastructure to both utilize and base the SSTO payload delivered on. And it has to be either 'dirt-cheap' (which even an 'expendable SSTO' design is debatable, see the Aquarius Expendable SSTO design: https://en.wikipedia.org/wiki/Aquarius_(rocket)) to manufacture and operate OR it has to be reusable AND dirt cheap to manufacture and operate.
There's a 'theory' that no one has done SSTO because of organizational and psychological reasons rather than practical or physical reasons. (G. Harry Stine and his book "Half Way to Anywhere" https://www.amazon.com/Halfway-Anywhere-Achieving-Americas-Destiny/dp/0871318059, uses this as a basis for 'why' SSTO keeps 'failing' for example) Trying to lay the "blame" for why no one is 'doing' SSTO on Air Force and NASA institutional and "not-invented-here" arguments but ignoring that almost any other nation can "do the math" the same as anyone in the US and the fact is the 'numbers' don't work out at well as advocates tend to think they do. Especially with the OTL lack of on-orbit infrastructure and lack of LEO servicing needs. You HAVE had several companies and nations do preliminary work on various SSTO concepts and programs, from ARCA's latest 'concept' vehicle, (Haas-2, http://www.arcaspace.com/en/haas2c.htm, https://newatlas.com/single-stage-rocket/48710/) using H2O2/Kerosene to put around 220lb into LEO to Japan's "RTV" program, (a subscale DC-X) to Indian concepts, (again mostly 'sub-scale' test articles) and the British Skylon concept, and others which continue to pop up on regular basis It is quite clear the onus in on the proposer not the lack of 'support' from the "main stream" aerospace industry.
ARCA for example is at least straight forward noting the 'advantage' of their vehicle is it "can be refueled on-orbit" eliminating the need for an upper stage, (thus requiring the capability exists on-orbit to do so) although they repeat the over-used justification that the SSTO has 'less parts' and is therefore more reliable where the SSTO requires very low margins to work so it is arguable that though 'fewer' the parts are in fact 'cheaper' or more reliable. The thing is the 'costs' are still not that much less than 'normal' (and this is an expendable vehicle keep in mind) with payload costs still over $4,000 dollars per pound. (And as of yet no test flight or test for that matter)
So it is reasonable to assume that there might be some fundemental issues with the concept. That's not to say it can't work, after all the "math" does in fact work out, it is more likely the 'assumptions' are flawed instead.
Randy
Ian_W
Banned
4t is almost exactly the mass of a 702SP all-electric satellite Boeing sells. Get it to LEO, it then makes it's own way to Geo under it's own power using it's own XIPS-25s.
Similarly, 4t is probably around 20 OneWeb satellites, once you add an adaptor, and they then do their orbit phasing with their own baby Hall Effect Thrusters.
It's a metric shedload of Doves, or other earth observation cubesats.
Yep. There's lots and lots of markets for 4t to LEO ... definitely a bigger market when you add it up than the number of things that need 80t in one lift to LEO.
Also, if we're doing Alternate History here, a base Mercury capsule was 1360kg, so if we add an OMS and a door so it can dock to the ISS (or equivalent), we have a nice little one person runabout that can shuttle to and from the space station.
While I'm on capsules, Gemini was 3851kg, but I'm not sure if that included astronauts ...
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I'll give Ian_W credit for attempting to come up with a "market/mission" but there's still some issues:
Ian_W wrote:
About half actually, (3,300lb to 5,100lb) by if course you'd need several extra pounds of Xenon propellant possibly a whole secondary XIPS since the engine would pretty much run its operations-life-time getting from LEO to GEO. That's assuming it would arrive which is actually doubtful since it would take months to traverse the Van Allen belts and the electronics probably won't make it. We push satellites through the Van Allen Belts for the same reason we do astronauts Taking months to a year to arrive at the operations position isn't optimum for a business.
https://en.wikipedia.org/wiki/Boeing_702#702SP
https://en.wikipedia.org/wiki/XIPS-25
Satellit mass is calculated to be between 386lb to 441lb so that's about right but again you'd need additional propulsion per satellite as the required operating time to phase them will run out the operational life-time clock on the station keeping systems. And again time required is going to be an issue.
https://en.wikipedia.org/wiki/Hall-effect_thruster
Which won't get permission to fly as there are already regulator and "traffic" control questions should the current crop of 'micro-sat' launchers actually start flying at any decent rate As is there are suggestions that cubesats and other 'private' LEO sats should have attached drag devices to bring them down in less than a year and that's (again) only with the assumed traffic the current crop of microlaunchers can handle. And the other issues is while micro-and-cubesats are willing to fly to non-optimal orbits since 'piggybacking' on large satellite launches is "free" (nominal integration costs) the whole thrust, (pardon the pun) of small launchers is they may cost a bit more but you get the satellite where you want it instead. 10,000lbs to LEO is vastly over-kill for the martket segment as you'd need under 1,000lbs at most for a 'flock' of cubesats. So the "1,000" has to pay for the full "10,000" which probably negates any cost savings not to mention you can only fly when you have at least "1,000" of payload.
Eh, the 'thing' is the main "Market" segment is only ONE of the things you've mentioned, (that being the LEO satellite constellations) and those are already teamed with a launch provider and planned launch vehicle. You have to prove cheaper AND convince an active partner, (SpaceX, Ariane, etc) to step aside and let you 'compete' the launch costs. Not likley.
All the smaller satellites are better served by a smaller payload to the desired destination system just as the bigger payloads need a similar bigger payload system. Delivery to LEO means you are ONLY half way to your destination and by itself the SSTO does not provide any way of getting to where the customer wants the cargo to be.
Now I'm not saying there are not ways to make it work, in fact there are some rather obvious ones which is what I've been hinting at but no one seems to be picking up. Quickly reviewing the 'criteria' from the OP:
{quote]SSTO means that spaceship must start, fly into space and land on space in one piece, without ejecting stages nor starting from another vehicle.[/quote]
See Single-Stage-To-Orbit is really less than useful and about the only concept that actually recognizes and attempts to address this is Skylon with its planned Reusable Upper Stage (https://en.wikipedia.org/wiki/Skylon_(spacecraft)) BECAUSE the designers specifically went out and designed towards servicing the KNOWN and quantifiable market of GEO Satellite delivery! So while Skylon is an "SSTO" it is and always has been a Two-Stage-To-Destination vehicle! (Though they have since dropped the information there were figures for the mass that Skylon could 'deliver' to orbit by staging an upper stage at velocities below orbital. Near as I can figure they rapidly ran out of volume available for such a notional upper stage and reverted to and orbit-to-orbit upper stage which it in the cargo bay)
So having an 'upper stage' to push your payload into a higher orbit would be within the criteria, but having said that I'll point out that including payload almost none of the known upprt stages (https://en.wikipedia.org/wiki/List_of_upper_stages) will fit.
(Actually the Payload Assist Module or STAR series of solid upper stages might work: https://en.wikipedia.org/wiki/Payload_Assist_Module,https://en.wikipedia.org/wiki/Star_(rocket_stage), http://www.astronautix.com/s/star48.html )
So a 2,313kg/5,100lb 702SP coupled with a Star48B1 PAM at 2,141kg/4720lb comes to a total of 4,454kg/9,820lb of the total payload. The actual 'key' to utility is the ability to deliver payload to where your customer wants it, (or very near to) and not to depend on your customer getting from where you dump him off to where he needs to be
1400kg/3,000lb for the heavist (Mercury-Atlas-9) version, add in around 240kg/529lbs of OMS in place of the Mercury retro-pack brings the total up to 1,640kg/3615lb. (http://www.braeunig.us/space/specs/mercury.htm) A docking or mating section could replace the cylinder where the parachutes were, (in fact there was an 'escape tunnel' that could be opened from inside the capsule and through which the astronaut could crawl out should the hatch be unable to be used) so throw on an additional 1000kg/2200lbs and call it 2,640kg/5829lbs. Still leaves around 1,891kg/4,171lb of your initial "payload" mass for fittings, structure and attachements. (Note there's no launch escape system though you could use the OMS ala Dragon/Dragon-II I suppose but that came to around 580kg/1,278lb)
Again though it's not very functional. If it's all you HAVE then it's fine but it begs the question of why you simple aren't building a better vehicle or at worst using the SSTO as a recoverable booster stage? A one-person 'runabout' or 'shuttle' isn't really useful and unless you're assuming it is somehow greatly easier to turn around rapidly or costs vastly less, (neither is a given remember) it's still only 'one' person OR about 3,628kg/8,000lbs of supplies. The delivered mass, (and again this assumes enough 'spare' delta-V to rendezvous and dock as well as return to Earth or at least reenter) as noted is slightly better than Progress or Dragon but less than ATV delivered.
Listed "launch" mass is 3851kg/8,490lbs so about 144kg/317lb of that total is for the 'crew' (http://www.braeunig.us/space/specs/gemini.htm)
The main issue is getting any kind of docking or berthing system on the Gemini given the design. The 'nose' is full of RCS jets, valves and piping and getting a good seal around either of the hatches is going to be problematical at best. What you want is something that carries at least two crew, (one and a spare) AND sufficient payload to make the trip worthwhile. It can be argued that a more 'advanced' Gemini, (or arguably something more similar to the actual Mercury Mk-II which was aimed at being a 'two-man-Apollo-analog' before they actually knew what Apollo would look like) designed from the start to include both rendezvoius AND docking along with transfer ability would fit the bill.
So dump the "Equipment Module" (1,278kg/2,817lb) and move a reduced "life/power/support" system into and replace the Retro Module (591kg/1,302lb) for a total of around 2,573kg/5,672lb for crew. Assume we can 'convert' the current mass of heat shield (144kg/317lb) recovery equipment (98kg/216lb) and probably the module specific RCS (33kg/72lb) propellant (total: 275kg/606lb) into a docking/berthing system allowing you to similiarly convert the "spare" 1,278kg/2.817lb mass into useful payload.
For those keeping track the bare crew mass of 144kg/317lb was for two crew members and their space suits. Seats and provisions is listed as 426kg/939lb. (@213kg/469lb per person) Which meant each crew member WITH suit couldn't weigh more than 72kg/159lbs! A more realistic (and workable) fraction would be 90kg/200lb to 113kg/250 with 'spare' mass spilling over to 'provisions'. Which is to say we can push the 'crew' delivery mass to around three or four people for a total of 5/6. (Actually it came out to 4.2 or 3.9 so call it 4 and a 'full' load of 6 I'd say. With a single "person" with suit, and seat and 'provisions' either 303kg/668lb low, or 326kg/718lb high)
So now we're talking 'useful' payload ranges though you'd have to use separate flights for crew and cargo but that's not as bad as it might seem. (A "passenger" version of the Dynasoar was once described as a very efficient way to get five (5) people into space... Note you couldn't really DO much with them as they had to crawl through a notional rear EVA hatch to get out but this is along those lines, http://www.astronautix.com/d/dynasoar.html, http://www.astronautix.com/graphics/x/x20xmew.jpg, http://up-ship.com/blog/?p=4894, but the changes to the "Gemini" would be extreme enough it wont' be Gemini anymore)
Specifically for an alt-history scenerio lets examine that last link in another post.
Randy
Ian_W wrote:
About half actually, (3,300lb to 5,100lb) by if course you'd need several extra pounds of Xenon propellant possibly a whole secondary XIPS since the engine would pretty much run its operations-life-time getting from LEO to GEO. That's assuming it would arrive which is actually doubtful since it would take months to traverse the Van Allen belts and the electronics probably won't make it. We push satellites through the Van Allen Belts for the same reason we do astronauts
Taking months to a year to arrive at the operations position isn't optimum for a business.https://en.wikipedia.org/wiki/Boeing_702#702SP
https://en.wikipedia.org/wiki/XIPS-25
Satellit mass is calculated to be between 386lb to 441lb so that's about right but again you'd need additional propulsion per satellite as the required operating time to phase them will run out the operational life-time clock on the station keeping systems. And again time required is going to be an issue.
https://en.wikipedia.org/wiki/Hall-effect_thruster
Which won't get permission to fly as there are already regulator and "traffic" control questions should the current crop of 'micro-sat' launchers actually start flying at any decent rate
As is there are suggestions that cubesats and other 'private' LEO sats should have attached drag devices to bring them down in less than a year and that's (again) only with the assumed traffic the current crop of microlaunchers can handle. And the other issues is while micro-and-cubesats are willing to fly to non-optimal orbits since 'piggybacking' on large satellite launches is "free" (nominal integration costs) the whole thrust, (pardon the pun) of small launchers is they may cost a bit more but you get the satellite where you want it instead. 10,000lbs to LEO is vastly over-kill for the martket segment as you'd need under 1,000lbs at most for a 'flock' of cubesats. So the "1,000" has to pay for the full "10,000" which probably negates any cost savings not to mention you can only fly when you have at least "1,000" of payload.Eh, the 'thing' is the main "Market" segment is only ONE of the things you've mentioned, (that being the LEO satellite constellations) and those are already teamed with a launch provider and planned launch vehicle. You have to prove cheaper AND convince an active partner, (SpaceX, Ariane, etc) to step aside and let you 'compete' the launch costs. Not likley.
All the smaller satellites are better served by a smaller payload to the desired destination system just as the bigger payloads need a similar bigger payload system. Delivery to LEO means you are ONLY half way to your destination and by itself the SSTO does not provide any way of getting to where the customer wants the cargo to be.
Now I'm not saying there are not ways to make it work, in fact there are some rather obvious ones which is what I've been hinting at but no one seems to be picking up. Quickly reviewing the 'criteria' from the OP:
{quote]SSTO means that spaceship must start, fly into space and land on space in one piece, without ejecting stages nor starting from another vehicle.[/quote]
See Single-Stage-To-Orbit is really less than useful and about the only concept that actually recognizes and attempts to address this is Skylon with its planned Reusable Upper Stage (https://en.wikipedia.org/wiki/Skylon_(spacecraft)) BECAUSE the designers specifically went out and designed towards servicing the KNOWN and quantifiable market of GEO Satellite delivery! So while Skylon is an "SSTO" it is and always has been a Two-Stage-To-Destination vehicle! (Though they have since dropped the information there were figures for the mass that Skylon could 'deliver' to orbit by staging an upper stage at velocities below orbital. Near as I can figure they rapidly ran out of volume available for such a notional upper stage and reverted to and orbit-to-orbit upper stage which it in the cargo bay)
So having an 'upper stage' to push your payload into a higher orbit would be within the criteria, but having said that I'll point out that including payload almost none of the known upprt stages (https://en.wikipedia.org/wiki/List_of_upper_stages) will fit.
(Actually the Payload Assist Module or STAR series of solid upper stages might work: https://en.wikipedia.org/wiki/Payload_Assist_Module,https://en.wikipedia.org/wiki/Star_(rocket_stage), http://www.astronautix.com/s/star48.html )
So a 2,313kg/5,100lb 702SP coupled with a Star48B1 PAM at 2,141kg/4720lb comes to a total of 4,454kg/9,820lb of the total payload. The actual 'key' to utility is the ability to deliver payload to where your customer wants it, (or very near to) and not to depend on your customer getting from where you dump him off to where he needs to be
1400kg/3,000lb for the heavist (Mercury-Atlas-9) version, add in around 240kg/529lbs of OMS in place of the Mercury retro-pack brings the total up to 1,640kg/3615lb. (http://www.braeunig.us/space/specs/mercury.htm) A docking or mating section could replace the cylinder where the parachutes were, (in fact there was an 'escape tunnel' that could be opened from inside the capsule and through which the astronaut could crawl out should the hatch be unable to be used) so throw on an additional 1000kg/2200lbs and call it 2,640kg/5829lbs. Still leaves around 1,891kg/4,171lb of your initial "payload" mass for fittings, structure and attachements. (Note there's no launch escape system though you could use the OMS ala Dragon/Dragon-II I suppose but that came to around 580kg/1,278lb)
Again though it's not very functional. If it's all you HAVE then it's fine but it begs the question of why you simple aren't building a better vehicle or at worst using the SSTO as a recoverable booster stage? A one-person 'runabout' or 'shuttle' isn't really useful and unless you're assuming it is somehow greatly easier to turn around rapidly or costs vastly less, (neither is a given remember) it's still only 'one' person OR about 3,628kg/8,000lbs of supplies. The delivered mass, (and again this assumes enough 'spare' delta-V to rendezvous and dock as well as return to Earth or at least reenter) as noted is slightly better than Progress or Dragon but less than ATV delivered.
Listed "launch" mass is 3851kg/8,490lbs so about 144kg/317lb of that total is for the 'crew'
(http://www.braeunig.us/space/specs/gemini.htm) The main issue is getting any kind of docking or berthing system on the Gemini given the design. The 'nose' is full of RCS jets, valves and piping and getting a good seal around either of the hatches is going to be problematical at best. What you want is something that carries at least two crew, (one and a spare) AND sufficient payload to make the trip worthwhile. It can be argued that a more 'advanced' Gemini, (or arguably something more similar to the actual Mercury Mk-II which was aimed at being a 'two-man-Apollo-analog' before they actually knew what Apollo would look like) designed from the start to include both rendezvoius AND docking along with transfer ability would fit the bill.
So dump the "Equipment Module" (1,278kg/2,817lb) and move a reduced "life/power/support" system into and replace the Retro Module (591kg/1,302lb) for a total of around 2,573kg/5,672lb for crew. Assume we can 'convert' the current mass of heat shield (144kg/317lb) recovery equipment (98kg/216lb) and probably the module specific RCS (33kg/72lb) propellant (total: 275kg/606lb) into a docking/berthing system allowing you to similiarly convert the "spare" 1,278kg/2.817lb mass into useful payload.
For those keeping track the bare crew mass of 144kg/317lb was for two crew members and their space suits. Seats and provisions is listed as 426kg/939lb. (@213kg/469lb per person) Which meant each crew member WITH suit couldn't weigh more than 72kg/159lbs! A more realistic (and workable) fraction would be 90kg/200lb to 113kg/250 with 'spare' mass spilling over to 'provisions'. Which is to say we can push the 'crew' delivery mass to around three or four people for a total of 5/6. (Actually it came out to 4.2 or 3.9 so call it 4 and a 'full' load of 6 I'd say. With a single "person" with suit, and seat and 'provisions' either 303kg/668lb low, or 326kg/718lb high)
So now we're talking 'useful' payload ranges though you'd have to use separate flights for crew and cargo but that's not as bad as it might seem. (A "passenger" version of the Dynasoar was once described as a very efficient way to get five (5) people into space... Note you couldn't really DO much with them as they had to crawl through a notional rear EVA hatch to get out but this is along those lines, http://www.astronautix.com/d/dynasoar.html, http://www.astronautix.com/graphics/x/x20xmew.jpg, http://up-ship.com/blog/?p=4894, but the changes to the "Gemini" would be extreme enough it wont' be Gemini anymore)
Specifically for an alt-history scenerio lets examine that last link in another post.
Randy
Ok back to a scenario or SSTO;
Assume that we never get past the Saturn-1 which is turned into a reusable (recovered down-range and refurbished) booster and the decision is made to go with a recoverable rather than 'cheap' S-IVB using the Douglas/Bono recovery kit. (Quoted as around 6,500lbs2948kg) In addition the Saturn and early Apollo (probably NOT the one we know) is used to pursue a LEO orbital station concept using Saturn launched modules:
http://up-ship.com/blog/?p=4894
(S-IVB recovery pic here)
Evolutionary upgrades continue in both the H1 and J2 engines with the eventual adaption of a plug-nozzle J2 of between 250,000lb to 300,000lb thrust. (Progression to the HG-3 engine: http://www.astronautix.com/j/j-2.html) Assuming, (and it's not a stretch) NASA is getting tired of the 'kludge' Saturn design they keep looking to an 'advanced' LH2 based launch vehicle and finally get Congress to sign off on development. But there's a significant budget issue and frankly some version of Saturn is going to still be doing the heavy lifting. So what they come up with is an LH2 powered SSTO based on the S-IVB stage and an expanded HG-3 plug-cluster. (Engine thrust will be about 600,000lbs versus the SSME's 418000lbs so despite the recovery and other systems we still have a good shot at the full 10,000lbs payload without boosters or assist stages)
The selling point as per OTL Shuttle is cheaper access with an SSTO that won't cost as much per flight as the full Saturn system. (Arguable considering OTL's Shuttle debate even though they are using the most expensive stage of the Saturn as a basis, but there was quite the hubris of "hydrogen will fix anything" going on OLT so...) Specifically using a "modified" Apollo CM (again probably not the one we know as this is the 'original' plan of use with Earth orbital as the main and "possibly" upgradeable to around-the-Moon at some point) which frankly is going to have to be 'ultra-light' and probably a set up for disaster at some point in the future as it will lack abort capability. On the other hand the initial version may use a "light weight" CM/SM combination as I suspect the budget and other constraints may force the initial capability to be only putting the Apollo into orbit with it and the booster recovering separately. ("Technically" violating the OP criteria but in my defense this is literally a continuation of what they are already doing and not that much of a technical stretch. It also allows abort capability to be retained AND does not require over 24 hour 'dwell' time on-orbit for the S-IVB stage so no need for extra insulation or such)
From this point it will eventually come to a point where the Apollo SM will be dropped and the CM will be mounted directly on the booster. Continued 'mass reduction' would include the CM heat shield and parachutes, (which can lead to a Challenger type incident obviously) and added crew positions. Depending on how influential the Astronaut Office is TTL we could see the vehicle being used 'unmanned' to delivery supplies directly to the station or 'minimum' manned (one astronaut in a "Mercury" analog capsule mounted above the 'cargo') with eventual addition of some sort of 'assist' system to push up the available payload to orbit. That's getting away from a "true" SSTO I know but pretty inevitable for a government system where payload is king.
Keep in mind though that at this point "someone" has in fact 'proven' that we can build and operate an SSTO so the door is wide open for someone else, (like the private sector or Russia, etc) to exploit this. But also being the spoilsport I am I'm going to point out that 'proving' any of the claims made for SSTO is going to be about as difficult as getting accurate figures for Shuttle operations and economics was OTL during its lifetime
More so the argument will be made that TSTO is more capable AND adding 'assists' to the SSTO will make IT that much more capable. This argument will carry even more weight if there IS a Challenger type incident due to the weight reduction measures for the SSTO.
Randy
Assume that we never get past the Saturn-1 which is turned into a reusable (recovered down-range and refurbished) booster and the decision is made to go with a recoverable rather than 'cheap' S-IVB using the Douglas/Bono recovery kit. (Quoted as around 6,500lbs2948kg) In addition the Saturn and early Apollo (probably NOT the one we know) is used to pursue a LEO orbital station concept using Saturn launched modules:
http://up-ship.com/blog/?p=4894
(S-IVB recovery pic here)
Evolutionary upgrades continue in both the H1 and J2 engines with the eventual adaption of a plug-nozzle J2 of between 250,000lb to 300,000lb thrust. (Progression to the HG-3 engine: http://www.astronautix.com/j/j-2.html) Assuming, (and it's not a stretch) NASA is getting tired of the 'kludge' Saturn design they keep looking to an 'advanced' LH2 based launch vehicle and finally get Congress to sign off on development. But there's a significant budget issue and frankly some version of Saturn is going to still be doing the heavy lifting. So what they come up with is an LH2 powered SSTO based on the S-IVB stage and an expanded HG-3 plug-cluster. (Engine thrust will be about 600,000lbs versus the SSME's 418000lbs so despite the recovery and other systems we still have a good shot at the full 10,000lbs payload without boosters or assist stages)
The selling point as per OTL Shuttle is cheaper access with an SSTO that won't cost as much per flight as the full Saturn system. (Arguable considering OTL's Shuttle debate even though they are using the most expensive stage of the Saturn as a basis, but there was quite the hubris of "hydrogen will fix anything" going on OLT so...) Specifically using a "modified" Apollo CM (again probably not the one we know as this is the 'original' plan of use with Earth orbital as the main and "possibly" upgradeable to around-the-Moon at some point) which frankly is going to have to be 'ultra-light' and probably a set up for disaster at some point in the future as it will lack abort capability. On the other hand the initial version may use a "light weight" CM/SM combination as I suspect the budget and other constraints may force the initial capability to be only putting the Apollo into orbit with it and the booster recovering separately. ("Technically" violating the OP criteria but in my defense this is literally a continuation of what they are already doing and not that much of a technical stretch. It also allows abort capability to be retained AND does not require over 24 hour 'dwell' time on-orbit for the S-IVB stage so no need for extra insulation or such)
From this point it will eventually come to a point where the Apollo SM will be dropped and the CM will be mounted directly on the booster. Continued 'mass reduction' would include the CM heat shield and parachutes, (which can lead to a Challenger type incident obviously) and added crew positions. Depending on how influential the Astronaut Office is TTL we could see the vehicle being used 'unmanned' to delivery supplies directly to the station or 'minimum' manned (one astronaut in a "Mercury" analog capsule mounted above the 'cargo') with eventual addition of some sort of 'assist' system to push up the available payload to orbit. That's getting away from a "true" SSTO I know but pretty inevitable for a government system where payload is king.
Keep in mind though that at this point "someone" has in fact 'proven' that we can build and operate an SSTO so the door is wide open for someone else, (like the private sector or Russia, etc) to exploit this. But also being the spoilsport I am I'm going to point out that 'proving' any of the claims made for SSTO is going to be about as difficult as getting accurate figures for Shuttle operations and economics was OTL during its lifetime
More so the argument will be made that TSTO is more capable AND adding 'assists' to the SSTO will make IT that much more capable. This argument will carry even more weight if there IS a Challenger type incident due to the weight reduction measures for the SSTO.
Randy
Again, it's not about the technology or the capabilities it's about impressions. An SSTO will "look" (and the assumption is act/cost/be/etc) like every other form of transportation we know. Trying to apply 'logic' tends to fail
Randy
ROMBUS had several interesting Features:
The plug nozzle rocket engine provides automatic altitude compensation and therefore good performance at both sea level atmospheric pressure and in space.
its plug nozzle base was also its heat shield for reentry.
Refueling ROMBUS in Orbit is easy
A ROMBUS with Liquid Oxygen tank as Payload is launch, during ascent the Payload tank empty its contents into ROMBUS internal Liquid Oxygen Tank
At Arrival in Orbit it got internal Oxygen Tank filled and empty Payload tank
A second ROMBUS is launch bringing Payload and Hydrogene Tanks into Rendezvous with first ROMBUS.
Payload and Hydrogene Tanks are connected with First ROMBUS and Second ROMBUS return with empty Payload tank to Earth
Phillip Bono proposed this approach for Moon Mission "Project Selena" and Mars Mission "Project Deimos"
Orion test sites were actually expected to survive well if prepared properly.
They study that problem, consider test site was Place in Nevada Test site know as "Jackass Flats", later used for testing Nuclear Engines for Aircraft and Spacecraft.
With testing the Orion puls unit with two concept: before 1963 overground, after 1963 underground in man made cave.
on proposed launch concept and Sites were several ideas:
mostly launching Orions from "Jackass Flats" one concept even proposed Silo launch like ICBM from Nevada
One ideas was to cover launch site in steel plate to reduce radioactive dust form Nevada launch.
Other proposed to launch the Orions from Swimming concrete platforms in middle of Pacific.
I know I'm going to get called a dangerous nut for carrying on with this- but how many atmospheric tests did we, the collective we on all sides of the cold war, carry out and spray fallout with for as near as dammit no purpose at all?
Without looking it up, memory suggests nearest round numbers of forty- five hundred tests, maybe fifteen hundred above ground, total maybe five to six hundred megatons disproportionately skewed to airburst, because the early tests for 'hey, it works' factor and sheer political intimidation were the largest.
The planet is already vastly more contaminated than you think- and to very little noticeable effect, really. Background levels hardly twitched. Granted I wouldn't go to Novaya Zemlya or Semipalatinsk on holiday, or Nevada or Ulithi- seriously, screw Vegas-
and I am aware of the isotopic issues that make pre atomic steel valuable, but apart from these places and the people in them at the time, the poor sods who got bombed by their own sides to see what would happen, the simplest guarantee of safety is the simplest form of shielding- one over range squared.
Also, following Coalition's link, there is a disqualifying condition; what's being described, the initial study, was designed to fit within the diameter of and be lofted to safe initiation altitude by the lower stage of a Saturn V. Conventional, disposable booster initially.
From the genuine Orion nut's point of view, that's why the performance numbers are so crap. Only seventy tons to Mars on a two hundred day flight from a single launch? Pathetic. But your first pulses would be after staging in the high upper atmosphere, well beyond the bulk of the air and the weather.
One of the things that seemed to work in theory was to coat the launch pad, and spray the pusher plate before each pulse, with graphite oil- liquid moderator, effectively, that prevented- minimized strictly speaking- ablation and activation as bomb residue. Silicon oil comes up in the sources too.
The other thing is that very small nuclear bombs are inherently unclean- they have difficulty burning up all their fissile, the core scatters before it can be completely consumed leaving lots of the very worst flavour of fallout. The NASA ten meter design was probably too small.
Design to avoid this problem, and you end up with something around the four thousand to ten thousand ton range; designs were sketched and performance drawn up for both. For the same mass on the pad or in the launch pit as one Saturn V, that single Interplanetary Orion could give you the science load of six hundred Apollo missions.
Considering what it cost, fiscally and in demanding engineering, to achieve what was done, and what it cost radiologically and ecologically to achieve nothing at all- yes, Orion would have been worth it.
Besides with, there's worse out there. Look up Zubrin drive- or NSWR. That's the apocalyptic nightmare option, the one that isn't reusable because you have nowhere to come back to once you start the burn. Pulse propulsion is downright sane by comparison.
Without looking it up, memory suggests nearest round numbers of forty- five hundred tests, maybe fifteen hundred above ground, total maybe five to six hundred megatons disproportionately skewed to airburst, because the early tests for 'hey, it works' factor and sheer political intimidation were the largest.
The planet is already vastly more contaminated than you think- and to very little noticeable effect, really. Background levels hardly twitched. Granted I wouldn't go to Novaya Zemlya or Semipalatinsk on holiday, or Nevada or Ulithi- seriously, screw Vegas-
and I am aware of the isotopic issues that make pre atomic steel valuable, but apart from these places and the people in them at the time, the poor sods who got bombed by their own sides to see what would happen, the simplest guarantee of safety is the simplest form of shielding- one over range squared.
Also, following Coalition's link, there is a disqualifying condition; what's being described, the initial study, was designed to fit within the diameter of and be lofted to safe initiation altitude by the lower stage of a Saturn V. Conventional, disposable booster initially.
From the genuine Orion nut's point of view, that's why the performance numbers are so crap. Only seventy tons to Mars on a two hundred day flight from a single launch? Pathetic. But your first pulses would be after staging in the high upper atmosphere, well beyond the bulk of the air and the weather.
One of the things that seemed to work in theory was to coat the launch pad, and spray the pusher plate before each pulse, with graphite oil- liquid moderator, effectively, that prevented- minimized strictly speaking- ablation and activation as bomb residue. Silicon oil comes up in the sources too.
The other thing is that very small nuclear bombs are inherently unclean- they have difficulty burning up all their fissile, the core scatters before it can be completely consumed leaving lots of the very worst flavour of fallout. The NASA ten meter design was probably too small.
Design to avoid this problem, and you end up with something around the four thousand to ten thousand ton range; designs were sketched and performance drawn up for both. For the same mass on the pad or in the launch pit as one Saturn V, that single Interplanetary Orion could give you the science load of six hundred Apollo missions.
Considering what it cost, fiscally and in demanding engineering, to achieve what was done, and what it cost radiologically and ecologically to achieve nothing at all- yes, Orion would have been worth it.
Besides with, there's worse out there. Look up Zubrin drive- or NSWR. That's the apocalyptic nightmare option, the one that isn't reusable because you have nowhere to come back to once you start the burn. Pulse propulsion is downright sane by comparison.
Michel Van wrote:
That was a Bono 'thing' for most of his VTVL designs which inspired others as well. (Phoenix, Beta, Roton, etc)
http://www.dtic.mil/dtic/tr/fulltext/u2/605210.pdf
(Note: This paper has a modified version of the ROMBUS with a more 'rounded' plug-nozzle than normal as it was found to help shed heat during entry and push the 'shock-wave' outward more to protect the engines. It also gives all the standard "answers" to the "why-SSTO" question, goes into some economics, and operational issues so is a good general read)
Being honest it's always 'easier' to replace a modular system such as the drop-tanks than it is to connect piping/hoses and such.
Still those tanks are the reason it doesn't fit the OP Though I will note that "Frontiers of Space" also suggested that the ROMBUS system could still reach orbit even if the tanks were retained. Why retain the tanks? They would be hinged at the bottom and a ram would 'spread' them during entry and terminal fall to increase drag (and by adjusting them allow some cross range maneuvering during descent) and a far lower terminal velocity.
While "Project Selena" would have used the basic ROMBUS the vehicle for "Project Deimos" was actually a special build and a bit larger. What I always found interesting about the Mars mission was the fact they didn't land the whole vehicle on the surface instead of the smaller lander. They'd have needed to pre-position or more likely rendezvous at Mars with some extra propellant tanks but it wasn't that complicated of a task. Turns out there were a couple of rather straight-forward reasons in that the main issue was getting anything down from the crew area to the surface and back up would be difficult at best. Secondary was doing so greatly complicated the design of the crew AG 'torus' module and associated systems.
In the "Project Selena" scenario only a couple of the tanks seen attached to the landed ROMBUS are actually propellant, (see the ROMBUS in the background which is lifting off to return to Earth orbit) with most of them being fitted out as living and working modules for the proposed Lunar Base. (Hence the Lunar "truck" is hauling one away from the ROMBUS and towards said base in the foreground)
Another interesting thing about the first picture is both the differences and "missions" suggested for the ROMBUS as you will note each 'vehicle' is slightly different. The ROMBUS on the right of course is a 'standard' service vehicle in this case used to bring up extra propellant tanks and/or converted tanks for living modules. It is often assumed the vehicle on the left is simply a crew carrier which is 'kind-of' is in that the structure on the top is a crew support and living module but it's 'purpose' is actually to house and support the assembly and operations crew for the duration of the assembly, check-out, and launch phase. Such a vehicle would be used for any on-orbit operations until and unless a more 'permanent' space base was in service. You'd think such a vehicle would be used to deliver the personnel for the "Selena" Lunar base but actually not.
Why? "Getting down" still remains an issue which was actually barely touched in any of the Douglas/Bono concept proposals Note in the second picture there's an astronaut on the surface 'supervising' the lowering of a tank/module and might wonder how he got there? Well you'll probably also note that one 'tank' is already in a lowered position as if awaiting the next truck to haul it away? Actually not That tank is a 'crew' module for the ROMBUS and it's lowered like that so that said crew can access the surface and vehicle. It will eventually get hauled away as part of the base while the ROMBUS returns to Earth under automatic control. (If we're getting 'technical' I'd point out they are lowering the 'wrong' tank as similar to the ROMBUS in the background the two opposing tanks would be propellant and the other 'module' tank would be the one opposite the already lowered one, but "artistic license" and all that tells me to shut up and enjoy the picture )
So finally there is the quite unusual center ROMBUS with a forward mounted 'payload' module structure. Normally the ROMBUS payload would be inside a 'fairing' aerodynamic cover which this does not look like but it's an option of course. Another possible answer was a proposed LH2 tank which would allow all the 'side' tanks to be modules as this would actually simplify the weight and balance issues. However the most likely explanation actually related to the "B" in the ROMBUS title: Booster.
One aspect of the ROMBUS as a booster was the proposal to use it as a replacement or supplement for the already developed Saturn-V vehicle. So an interstage was suggested that could adapt the ROMBUS to boost payloads sized and mounted on stages such as the S-II or the S-IVB for enhanced deep space missions. This structure looks very much like the concepts for such a stage adapter. Of course being used in such a 'booster' manner it's doubtful the ROMBUS would actually be on-orbit but keep in mind as a 'booster' (especially a hydrolox propellant one) simply refueling it on-orbit allows it to push payloads all over Cis-Lunar Space.
Of course like the SERV concept its very size (and payload) work(ed) against it. It not only was going to take a lot of rebuilt and new infrastructure and neither the politics nor finances were there to support the effort needed to get them flying.
("Go big or stay home!" I know but we still have to deal with SOME reality after all )
Randy
That was a Bono 'thing' for most of his VTVL designs which inspired others as well. (Phoenix, Beta, Roton, etc)
http://www.dtic.mil/dtic/tr/fulltext/u2/605210.pdf
(Note: This paper has a modified version of the ROMBUS with a more 'rounded' plug-nozzle than normal as it was found to help shed heat during entry and push the 'shock-wave' outward more to protect the engines. It also gives all the standard "answers" to the "why-SSTO" question, goes into some economics, and operational issues so is a good general read)
Being honest it's always 'easier' to replace a modular system such as the drop-tanks than it is to connect piping/hoses and such.
Still those tanks are the reason it doesn't fit the OP
Though I will note that "Frontiers of Space" also suggested that the ROMBUS system could still reach orbit even if the tanks were retained. Why retain the tanks? They would be hinged at the bottom and a ram would 'spread' them during entry and terminal fall to increase drag (and by adjusting them allow some cross range maneuvering during descent) and a far lower terminal velocity.While "Project Selena" would have used the basic ROMBUS the vehicle for "Project Deimos" was actually a special build and a bit larger. What I always found interesting about the Mars mission was the fact they didn't land the whole vehicle on the surface instead of the smaller lander. They'd have needed to pre-position or more likely rendezvous at Mars with some extra propellant tanks but it wasn't that complicated of a task. Turns out there were a couple of rather straight-forward reasons in that the main issue was getting anything down from the crew area to the surface and back up would be difficult at best. Secondary was doing so greatly complicated the design of the crew AG 'torus' module and associated systems.
In the "Project Selena" scenario only a couple of the tanks seen attached to the landed ROMBUS are actually propellant, (see the ROMBUS in the background which is lifting off to return to Earth orbit) with most of them being fitted out as living and working modules for the proposed Lunar Base. (Hence the Lunar "truck" is hauling one away from the ROMBUS and towards said base in the foreground)
Another interesting thing about the first picture is both the differences and "missions" suggested for the ROMBUS as you will note each 'vehicle' is slightly different. The ROMBUS on the right of course is a 'standard' service vehicle in this case used to bring up extra propellant tanks and/or converted tanks for living modules. It is often assumed the vehicle on the left is simply a crew carrier which is 'kind-of' is in that the structure on the top is a crew support and living module but it's 'purpose' is actually to house and support the assembly and operations crew for the duration of the assembly, check-out, and launch phase. Such a vehicle would be used for any on-orbit operations until and unless a more 'permanent' space base was in service. You'd think such a vehicle would be used to deliver the personnel for the "Selena" Lunar base but actually not.
Why? "Getting down" still remains an issue which was actually barely touched in any of the Douglas/Bono concept proposals
Note in the second picture there's an astronaut on the surface 'supervising' the lowering of a tank/module and might wonder how he got there? Well you'll probably also note that one 'tank' is already in a lowered position as if awaiting the next truck to haul it away? Actually not That tank is a 'crew' module for the ROMBUS and it's lowered like that so that said crew can access the surface and vehicle. It will eventually get hauled away as part of the base while the ROMBUS returns to Earth under automatic control. (If we're getting 'technical' I'd point out they are lowering the 'wrong' tank as similar to the ROMBUS in the background the two opposing tanks would be propellant and the other 'module' tank would be the one opposite the already lowered one, but "artistic license" and all that tells me to shut up and enjoy the picture )So finally there is the quite unusual center ROMBUS with a forward mounted 'payload' module structure. Normally the ROMBUS payload would be inside a 'fairing' aerodynamic cover which this does not look like but it's an option of course. Another possible answer was a proposed LH2 tank which would allow all the 'side' tanks to be modules as this would actually simplify the weight and balance issues. However the most likely explanation actually related to the "B" in the ROMBUS title: Booster.
One aspect of the ROMBUS as a booster was the proposal to use it as a replacement or supplement for the already developed Saturn-V vehicle. So an interstage was suggested that could adapt the ROMBUS to boost payloads sized and mounted on stages such as the S-II or the S-IVB for enhanced deep space missions. This structure looks very much like the concepts for such a stage adapter. Of course being used in such a 'booster' manner it's doubtful the ROMBUS would actually be on-orbit but keep in mind as a 'booster' (especially a hydrolox propellant one) simply refueling it on-orbit allows it to push payloads all over Cis-Lunar Space.
Of course like the SERV concept its very size (and payload) work(ed) against it. It not only was going to take a lot of rebuilt and new infrastructure and neither the politics nor finances were there to support the effort needed to get them flying.
("Go big or stay home!" I know but we still have to deal with SOME reality after all
)Randy
Of course like the SERV concept its very size (and payload) work(ed) against it. It not only was going to take a lot of rebuilt and new infrastructure and neither the politics nor finances were there to support the effort needed to get them flying.
("Go big or stay home!" I know but we still have to deal with SOME reality after all
SERV?
Yay, excuse to post
"Survive" yes, but the devil is in the details
"Jackass Flats" was the official test site for the NERVA nuclear engine since inception in the late 50s along with the PLUTO nuclear ramjet. The nuclear aircraft engines were actually built and tested in Idaho. Testing of the 'pulse' units was initially considered to be 'covered' in the standard above-ground testing program it was however rapidly found out that there were 'problems' with this idea due to the nature of the pulse units themselves. Mostly that they would direct a significant amount of energy in a single direction AND this is a 'bad' thing because if 'up' they would be hard to measure for effectiveness and energy 'impact' on a notional pusher plate. 'Down' was actually worse because it was calculated that at any reasonable detonation distance, (these couldn't be air dropped had to be 'tower' shots and the relatively low distance involved would cause serious contamination issues) due to plasma impact. Underground was considered but there were real questions of how good the data would be due to being in an enclosed space. They were having headaches enough with the planning for testing the pusher plate and shock-absorber system using 'plates' of high explosives
Dust, as noted was the main issue with ground launch as the fireball would (obviously) be in contact with the ground from the first shot. Then there was EMP and fall out debris from the atmospheric transit phase which rapidly showed any launch from the US would in effect cause more "fallout" (politically and problematically rather than radioactive
) than could be justified in ANY circumstances short of "world-ending-catastrophe".(How bad? Estimates were over 1,000 minimum people blinded or with severe eye injury even if warned NOT to look. Ground of ALL air traffic across the US for an eastward launch, including air traffic in southern Canada and northern Mexico and depending on trajectory "probably" the Caribbean and parts of the South Atlantic just to be 'safe'. Minimum of several million dollars damage to the US and probably northern Mexico electrical grid and communications systems. High possibility of wider damage to other systems world wide. Likelihood of damage to satellites and space infrastructure was high, and only got higher as more was put up. Definite surge in the Van Allen belt radioactivity level and upper atmosphere but the former was more worrisome than the latter which was predicted to dissipate rapidly.)
Silo launch conveyed no advantages and was never seriously considered what the supposed "silo" you see in some illustrations was for was BUILDING the Orion, not launching it
It was literally 'easier' to build it in a hole Ocean launch was actually coming in at the 'top' of the list for launch options since it would be on par with building a 'battleship' rather than a normal rocket vehicle. (The same argument as for SeaDragon
) Actually 'starting' from the ocean was considered since it would 'mitigate' the fall out issues and could be done from the literal 'middle-of-nowhere' in the Pacific but there were obvious logistical and operational issues even if you ignore the contamination issues.In the end one reason the Air Force 'accepted' the small Orion despite it's issues was there was really no consensus on how you'd launch a bigger one from the Earth's surface. Any way you tried had significant (no unsolvable mind you) issues.
Since then we've gotten enough knowledge under out belts to probably get away with some form of 'surface' launching an Orion, (as noted the Nuclear Verne Gun is workable) IF we had any compelling reason to. Couple that with the advanced work on other forms of pulsed nuclear yield, (Z-pinch, laser detonation, etc) we might even be capable of actually getting an Orion to fly IF we have enough reason. But it will keep coming directly back to that issue; There has to be a REALLY good reason to do so and rather frankly by the time we HAD such a reason it would probably be far to late to get one built and flying. Which of course should obviously be a reason why we should be working on one "just in case" anyway but...
Randy
No you'd be called a 'dangerous nut' for suggesting "Operation Sealion" was plausible on these forums... Orion? Phhht, minor stuff
"Atmospheric" test? About 520 so far less than you'd think. (https://en.wikipedia.org/wiki/List_of_nuclear_weapons_tests) Evidence suggsest a little over 1,300 total 'underground' tests since about 1957 but the data is only 'current' to about 1993-ish.
And the testing DID have a purpose and still does we just didn't fully understand the issues and by the time we did both the 'Comprehensive Test Ban' and anti-nuclear hysteria had reached a point where going underground was really the only viable option. (And frankly above-ground testing was more difficult to monitor and 'hide' anyway)
Actually if you want to get 'technical' about it most testing in the US did not in fact effect those considered "Down winders" despite the government resistance to admitting any effects. Radiation levels DID spike in nearby places such as Utah and New Mexico but MOST of the radioactive fallout was carried into places like Michigan and Wisconsin where elevated radioactivity was found for MONTHS after each test. Sediment samples from the Great Lakes are in fact categorized by 'pre-Atomic' and 'post-Atomic' with great accuracy due to contamination levels
The problem with that is the Orion puts radioactive debris in the upper atmosphere where it falls on ANYONE and in fact eventually EVERYONE at some point 'down-the-road'. Yes later bombs can in fact be made a LOT cleaner than bombs of the 60s or even 70s but they still had a lot of byproducts. The 'good' thing was we've learned how to get more bang with less fissile material over the decades so the contamination level keeps going down. Having said that of course there are those who will always consider any number above "zero" as too much...
(Moved)
Again the 'results' were very much not "nothing" and in fact the 'results' of Orion a LOT less obvious than it might seem. I'll go into more below but keep in mind that Orion is NOT "just" a spacecraft but a whole 'industry' and public/political mine field that was quite obvious to those who worked on it and knew about it. (Which was NOT the general public at the decision point) Consider that part of the 'byproduct' of Orion work was smaller nuclear weapons, a vastly increased nuclear weapons production infrastructure, and "small" things like city-destroying directed energy weapons capable of wiping Russian cities off the map from low Earth orbit to name JUST a few...
Hence "Nova", "Nexus" "ROMBUS" and such to loft the bigger Orion's to altitude
And in the latter cases you get to reuse the booster so bonus! Going to point out though you really only want to launch an Orion once. Bringing it back is just a waste of time and effort. Once on-orbit, (preferably high or medium of not geosynchronous orbits) you supply and 're-fuel' them with more 'conventional' infrastructure.[quoteOne of the things that seemed to work in theory was to coat the launch pad, and spray the pusher plate before each pulse, with graphite oil- liquid moderator, effectively, that prevented- minimized strictly speaking- ablation and activation as bomb residue. Silicon oil comes up in the sources too.[/quote]
The graphite oil/liquid moderator I've heard quoted by William Black for his 'ground-launched-Orion' stuff which he said is in the reports. I didn't see it but then again the stuff I read mostly came down on the side of simply 'not' launching from the ground. Mostly for the reasons listed above. The silicon oil was IIRC what was used on the pusher plate to help prevent ablation damage. Could be 'worse' I suppose, heard of HELIOS?
http://up-ship.com/blog/?p=5353
https://en.wikipedia.org/wiki/Helios_(propulsion_system)
Explode those bombs INSIDE the thrust chamber (with a lot of water to use as reaction mass) and off you go
And they couldn't, (mostly due to having to 'fit' the perimeters of the Saturn-V) really 'cash-in' on the mass and scale robustness of the bigger Orion's. But it was also about the logical extent of what you could reasonably 'ground' launch without too much issues. Really you could go up to about 20 meters but even the Air Force was having issues with getting anything bigger to work without the 'launch' issues getting to massive.
Actually 'avoiding' the problems was the main issue with the BIGGER (not smaller) Orion's. You couldn't NOT have to ground launch anything much over 20 meters and in fact while the Orion works BETTER the bigger it is the issue is getting it into space in the first place.
Fun alt-history (making) fact; The US Air Force by about late 1963-ish was of the position that they would WILLINGLY put about 1/3rd (or more, see: http://www.thespacereview.com/article/2714/1) of their TOTAL budget towards a program to design, build and put into service a version of the "Orion Battleship" (http://www.projectrho.com/public_html/rocket/realdesigns2.php, yes the freaking 4,000 ton version) "Deep Space Deterrent" force with the NEXUS chemical booster to loft it initially. Kennedy had already declared the Lunar Goal and NASA was dedicated towards Apollo and a Moon landing within 10 years and Orion was moved from the Air Force, (who'd already decided this wasn't a fight they could get into by that time) and by 1964 the Lunar priority had significantly reduced funding for anything in NASA not directly related to the Apollo program.
So what? There was one person who argued VEHEMENTLY with Kennedy that the goal of reaching the Moon in under a decades was in fact too LOW of a goal and that the US should in fact commit to a more ambitious goal of a PLANETARY mission instead. And who was this person? Robert McNamara! The Secretary of Defense believed that despite the upcoming ability of the US to loft similar if not larger payloads into orbit than the Soviets, (Saturn-1 had flown in 1961 and was capable, with planned upper stages, of putting up more payload per flight than anything the Soviets had) this state would probably not last and at the time it was unclear if the Saturn-V would fly or when. I'd like to speculate that had he had more time to prepare and do his usual 'due diligence' study of the issue AND gotten wind of the Air Force's likely commitment to such a project that he is perfeclty capable of putting two-and-two together:
Orion is VASTLY more capable of a spacecraft than anything else then or near-term technology was going to provide. On the other hand, it wasn't going to be either cost effective or feasible to use on a regular basis from the Earths surface. On the gripping-hand, NASA and Saturn offered a viable basis for a possible cost-effective transport system from Earth to low Earth orbit if given proper support and incentive AND at a cost far less than the proposed Lunar program. Orion on the other hand could be 'mostly' paid for by the military while 'public' funding went to a NASA program. In effect the two systems would complement and synergistic-ly support each other if properly directed and supported.
Showstopper: Everything else aside Orion is in the end a POLITICAL decision above economics, technology, or even possibilities. First and foremost even if the actual 'purpose' of the Orion is kept secret, (the Air Force couldn't keep its mouth shut) the plain fact is that the US nuclear industry would have to be optimized and rebuilt to build an average of several hundred (over 200 to 300 since each 'flight' could take nearly a thousand units each) nuclear weapons per year on a continuing basis which quite frankly COULD each be used as an offensive weapons warhead. It's doubtful there could be any meaningful discussion of nuclear control, limitation, or disarmament with such production levels no matter how much inspection of other limitations were offered. Secondly and probably more importantly the Orion would in effect be a thousand times worse from the view of the Soviet Union which at the time was SURROUNDED by American nuclear weapons. (The main reason for moving missiles into Cuba was in effect to offer 'some' counter to those warheads and look where THAT went) Now America would have something with HUNDREDS if not THOUSANDS of warhead flying directly over Russia every single day. How do you 'spin' that to a government and society that was already paranoid over the threat of the OTHER thousand warheads you have already aimed at them?
I have, (as you may have figured out
) notes on how this conversation would go and a nice little 'cliff-hanger' ending since quite obviously Mac would defer the decision to Kennedy on the matter. But frankly I don't see any way Kennedy CAN agree with the idea no matter how it's put to him. I'd like to think he'd end up considering it but even if this all comes out before the Cuban Missile Crises the situation is one where the Soviets will have little choice but to either respond in kind with all that implies to the Space and Nuclear Arms Race or rally the world against the US doing this. (And yes that's a very big 'factor' to think about) I suspect that Kennedy will quietly set this 'option' aside and go with the as-we-know-it Lunar program but can't really figure out WHAT he'd decide. The implications are just that big all around...Actually this is more than a bit of a 'straw-man' argument; NSWR was never suggested or even considered for any application OTHER than 'deep space' (beyond Cis-Lunar actually) use whereas (obviously) Orion was considered and studied for direct flight from Earth. Orion is arguably a viable spacecraft design in some circumstances (and I have believe me
) but at the same time we have to keep in mind that there are 'circumstances' and possibilities but take into account what's plausible and possible. I'd argue that if we really look at it Orion CAN in fact be argued to be a possible outcome but not in a general way and not unless we take ALL the relevant factors into consideration.Randy