Hammerbolt
Donor
What about the proposals for a rocket sled? Or the more modern version using a maglev? Launch a shuttle-like vehicle using one.
AHC/PC: SSTO - "Single Stage to Orbit" vehicle
- Thread starter Tal Shiar
- Start date
Randy,
Dathi summed it up nicely without bringing in enthalpy, as I was planning to do. As I recall the H2 was to be liquid with about 1/3 frozen material. The additional 58 kJ/Kg would increase the total phase change heat absorption of the hydrogen by about 5%, which would make the difference between impossible and impractical.
As for the clients, the first was in Akron, Ohio, the other in San Diego.
Dynasoar
Dathi summed it up nicely without bringing in enthalpy, as I was planning to do. As I recall the H2 was to be liquid with about 1/3 frozen material. The additional 58 kJ/Kg would increase the total phase change heat absorption of the hydrogen by about 5%, which would make the difference between impossible and impractical.
As for the clients, the first was in Akron, Ohio, the other in San Diego.
Dynasoar
These details of the Atlas 10B SCORE launch in 1958 make it sound extremely dodgy (virtually everything stripped out, including range safety), but it’s probably the closest thing ever to a SSTO. The mass on-orbit variously given as 8660lb or 8750lb must have been the highest for some time - until Saturn I?
Just got to put in a word for my favouritest AH thing, Project Orion- you probably could land, reload and re-use one, but it would take a lot of infrastructure and some space presence already. What you need is a small inland sea and a hell of a lot of earthmoving equipment. Step One is to Verne- gun it, single large propulsion charge in underground cavern, very limited fallout, thing goes foom off to the black horizon.
With unsustainable, human- squishing acceleration, in fact. So- and as Ford Prefect would say, this is the clever bit- you don't quite hit escape velocity. Get the thing moving fast enough to go out on a long elliptical orbit, yes- so your actual passage crew, waiting in their orbital shuttle, can catch, board and commission the thing, and go and do tens of thousands of tons of cool space stuff.
Where the inland sea comes in- the Aral would have been ideal- is that that is your descent target. Pusher plate as heatshield; ride that down- answers as to how to steer an Orion on an environmental impact statement please- second last fraction of payload would be drogues opening the world's largest paraglider, or better yet ballutes- because those could double as flotation bags.
You tow the light, unloaded Orion to the shore, where you have earlier dug a canal, that leads to a nice deep flooded pit. fill in the canal behind you, ideally with something groundwater doesn't seep through much. Load, and lower your re- readied Orion to the floor of the pit by pumping out. That then, dry and separated from the landing lake, becomes your new Verne gun. Repeat.
Count it, one megaton range underground nuclear test equivalent on Earth, one sequence near Earth to reduce from orbital transfer to re- entry velocity; this may actually be more environmentally friendly than lobbing the same mass up by conventional rocketry. Are we cooking with plutonium or what?
With unsustainable, human- squishing acceleration, in fact. So- and as Ford Prefect would say, this is the clever bit- you don't quite hit escape velocity. Get the thing moving fast enough to go out on a long elliptical orbit, yes- so your actual passage crew, waiting in their orbital shuttle, can catch, board and commission the thing, and go and do tens of thousands of tons of cool space stuff.
Where the inland sea comes in- the Aral would have been ideal- is that that is your descent target. Pusher plate as heatshield; ride that down- answers as to how to steer an Orion on an environmental impact statement please- second last fraction of payload would be drogues opening the world's largest paraglider, or better yet ballutes- because those could double as flotation bags.
You tow the light, unloaded Orion to the shore, where you have earlier dug a canal, that leads to a nice deep flooded pit. fill in the canal behind you, ideally with something groundwater doesn't seep through much. Load, and lower your re- readied Orion to the floor of the pit by pumping out. That then, dry and separated from the landing lake, becomes your new Verne gun. Repeat.
Count it, one megaton range underground nuclear test equivalent on Earth, one sequence near Earth to reduce from orbital transfer to re- entry velocity; this may actually be more environmentally friendly than lobbing the same mass up by conventional rocketry. Are we cooking with plutonium or what?
The earliest SSTO vehicle I'm aware of was proposed by Ed Hinemann of Douglas, for the Navy in 1946. Like the much later Atlas, it was an inflated structure. No significant payload, but I couldn't fault the report.[/QUOTE
What was the concept called? I recall seeing a concept where the air-frame was literally supported by pressurized nitrogen gas with a very light weight thrust structure and payload system that was supposed to be "SSTO" but you had to literally cut the payload out of the vehicle to get at it on-orbit
Randy
Ed Heinemann's proposed 1946 SSTO project was conducted for the Office Of Naval Research. The report itself was titled: "Preliminary Design of a Satellite" and was dated in August, 1946. According to my notes it was Douglas Aircraft Report ES 20636. Not certain where I saw it- Could have been on a trip to Naval Post Graduate School or at Rand Corp. Initially the vehicle itself was to be the payload
Dynasoar
trurle
Banned
Rocket sled is just booster forced out of optimal ascent trajectory by terrain. Completely meaningless. Maglev is simply not up to the task - we are struggling to get even 250m/s with maglevs currently.
trurle
Banned
Please find another humankind for such project. Orion drive is the propulsion option of last resort - when you have nothing valuable left behind the rear edge of pusher plate.
Ian_W wrote:
And right back at ya!
Launch Vehicle Performance Calculator. (Note you need some accurate figures for dry and propellant mass for this just FYI)
http://silverbirdastronautics.com/LVperform.html
trurle wrote:
Most 'true believers' really do think all you need is concrete pad to take off and land on The fact that no SSTO can pass the required noise ordinances is just a 'technicality' What is truly annoying is the insistence that IF some form of 'assist' is required it will be somehow, "smaller, cheaper, and safer" than anything currently in use. As an ex-Munitions Technician who has handled "Solid Rocket Motors" from 2.75" to ICBM stages I get rather 'ticked' when such handling is 'blown-off' with a simple "we'll only need small ones and though they will be jettisoned after use it will be done in a 'controlled' and 'safe' manner unlike any current SRBs" No, they will cost and be used the same as 'current' SRBs so no, you won't be taking off from a concrete pad in the city center just because you want to...
Ya, while SpaceX shows videos of the BFR launching from pad 39A it's questionable if they pad or Kennedy itself can handle such a beast. Off-shore launch, (and landing) sounds a lot more plausible.
From my studies of Air Launch as an assist system I've found the hierarchy of additives is as follows more or less in this order:
1) Speed, the faster your launch assist gets your vehicle at 'launch' the better
2) Altitude, the higher the better
3) Angle-of-Attack or Angle above the local horizon. The 'sweet-spot' seems to be between 50 and 80 degrees above the horizon depending on the speed and altitude of the LV at the time it starts its own engines.
The use or consideration of "Launch Assist" is very often dismissed out of hand by many advocates because it adds complexity and cost to the 'pure' SSTO concept. The problem is when they DO need it they go out of their way to avoid calling it an 'assist' or worse a 'stage' despite that being exactly what it is. And as I noted SSTO's tend to have marginal payloads anyway so any 'assistance' should be welcomed. But it is part and parcel of the basic assumption I find prevalent among advocates; Cost and accessibility will only come down when Launch Vehicles look and act like aircraft or any other Earth transport system. Since aircraft, cars, and trains do not use 'assist' devices...
I can see the draw of the logic but as I always point out; "Airplanes are not Spacecraft and vice-versa" and the few exceptions prove rather than dispute the rule. One of the main reasons I'm more of a TSTO advocate is simply that with two stages you can optimize both for the regime and environment they are working in which will actually make the overall costs of operations less. One of the "issues" I have with SpaceX and the Falcon-9 is they REALLY need to invest In a more efficient upper stage propellant and propulsion as RP1/LOX is abysmal. Many people are hoping for a Methane/LOX upper stage to be based on the BFR work but I think Musk has been adamant they won't be making such a change. My own hope was cryogenic propane which has the advantage that it fits into the current RP1 tankage and is around LOX temperature which makes things a lot easier. Further it has a bit over 80% of the ISP advantage or Hydrogen (just a tad lower than Methane in fact) but would probably require about as much engine work as getting a methalox engine up and running so...
The key is injector design and propellant choice and as I noted the concept has been around and on-again-off-again studied during that time. Much as I dislike SCRamjets I have to admit the research into injectors, mixing and combustion have gone a long way to solving many of these issues so that the concept is much more viable than when it first came out. (1950s) Also as I noted the concept was found to be applicable (in thrust augmentation mode since you don't need to address over/under expansion in these engines) to aerospike and plug-nozzle engines.
Actually let me be clear, the Venturestar at the end was heavily modified and looked almost nothing like the proposed X33 anymore. It had an external cargo 'bay/pod' and large wings to balance out the engine mass. The X33 itself had dropped in capability from reaching speeds of Mach-8 to "maybe" being capable of hitting Mach-6 and 'instrument' payload had dropped by almost half. Part of the reason the Air Force dropped out so soon was the area of research the X33 could cover wasn't going to be any better than the X-15 if not worse so they would derive no useful data from it.
It is often pointed to the issues with the composite LH2 tank as 'proving' the technology was not there to do SSTO but keep in mind that less than a year after Lockheed-Martin's failure Northrop Grumman delivered a composite LH2 tank to NASA for testing that worked fine. The tank failed for LM because they choose to ignore the sub-contractor they hired to build the tanks and use materials that were understood not to work with LH2. Someone convinced them they could simply 'line' the tanks but this didn't address the actual materials problems.
It depends I think. Though the 'suggestion' from the video's is that the main booster will be nothing more than a "super" Falcon-9 the fact that they are thinking ahead with the ITS stage and are using lifting-body reentry is I think telling. Especially since Musk has historically vehement against any lifting reentry concepts. I highly suspect the "super-Falcon" booster is an artistic placeholder till they do more work on it. A lot depends on where they build both stages as transportation is going to be a major deciding factor. I'd not be surprised to see the booster morph into a more conical vehicle somewhat like the SERV (http://www.astronautix.com/s/serv.html,http://www.pmview.com/spaceodysseytwo/spacelvs/sld034.htm) or Gomersall SSTO concept, (http://www.aerospaceprojectsreview.com/catalog/spacedoc42.jpg) which will be vastly more stable and easier to cover with TPS. The main challenge would be the non-cylindrical tankage and size thereof but I don't suspect that with effort, (and motivation) SpaceX would shy away from the challenge.
Dathi THorfinnsson wrote:
As I've noted before you (I) learn something new here every day I didn't know the JAXA design used slush-hydrogen, I know that REL's Skylon/SABRE does not but as noted they are not going as far as turning the air liquid but just deep cooling it.
Hammerbolt wrote:
Or even the "Closed End Launch Tube" pneumatic concept, (https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20010027422.pdf) depending on how much 'oomph' you need
That's up to Tal Shiar as it's his challenge but the argument could be made that it is a form of 'staging' and detracts from the 'flying into space on its own' portion.
Part of the "draw" as trurle and I discussed above for SSTO is the idea that it would need 'less' infrastructure and operational facilities than a "standard" launch vehicle. Being something that could not only achieve 'aircraft' like operability but similar operations, ("launch from the local airport" and all that) which would directly relate to reduced costs. Rather obviously any major 'construction' such as the rocket sled, MagLev, or such is viewed as violating the KISS principle and the minimum costing no matter how much it might make the actual operations cheaper and/or easier. Which is of course counter-intuitive initially but really no form of transportation exists without significant infrastructure in the modern world and the more sophisticated and 'powerful' the more it requires so the "hope" of limiting the required infrastructure as a cost saving measure is rather forlorn to say the least.
Randy
And right back at ya!
Launch Vehicle Performance Calculator. (Note you need some accurate figures for dry and propellant mass for this just FYI)
http://silverbirdastronautics.com/LVperform.html
trurle wrote:
Most 'true believers' really do think all you need is concrete pad to take off and land on
The fact that no SSTO can pass the required noise ordinances is just a 'technicality' What is truly annoying is the insistence that IF some form of 'assist' is required it will be somehow, "smaller, cheaper, and safer" than anything currently in use. As an ex-Munitions Technician who has handled "Solid Rocket Motors" from 2.75" to ICBM stages I get rather 'ticked' when such handling is 'blown-off' with a simple "we'll only need small ones and though they will be jettisoned after use it will be done in a 'controlled' and 'safe' manner unlike any current SRBs" No, they will cost and be used the same as 'current' SRBs so no, you won't be taking off from a concrete pad in the city center just because you want to...Ya, while SpaceX shows videos of the BFR launching from pad 39A it's questionable if they pad or Kennedy itself can handle such a beast. Off-shore launch, (and landing) sounds a lot more plausible.
From my studies of Air Launch as an assist system I've found the hierarchy of additives is as follows more or less in this order:
1) Speed, the faster your launch assist gets your vehicle at 'launch' the better
2) Altitude, the higher the better
3) Angle-of-Attack or Angle above the local horizon. The 'sweet-spot' seems to be between 50 and 80 degrees above the horizon depending on the speed and altitude of the LV at the time it starts its own engines.
The use or consideration of "Launch Assist" is very often dismissed out of hand by many advocates because it adds complexity and cost to the 'pure' SSTO concept. The problem is when they DO need it they go out of their way to avoid calling it an 'assist' or worse a 'stage' despite that being exactly what it is. And as I noted SSTO's tend to have marginal payloads anyway so any 'assistance' should be welcomed. But it is part and parcel of the basic assumption I find prevalent among advocates; Cost and accessibility will only come down when Launch Vehicles look and act like aircraft or any other Earth transport system. Since aircraft, cars, and trains do not use 'assist' devices...
I can see the draw of the logic but as I always point out; "Airplanes are not Spacecraft and vice-versa" and the few exceptions prove rather than dispute the rule. One of the main reasons I'm more of a TSTO advocate is simply that with two stages you can optimize both for the regime and environment they are working in which will actually make the overall costs of operations less. One of the "issues" I have with SpaceX and the Falcon-9 is they REALLY need to invest In a more efficient upper stage propellant and propulsion as RP1/LOX is abysmal. Many people are hoping for a Methane/LOX upper stage to be based on the BFR work but I think Musk has been adamant they won't be making such a change. My own hope was cryogenic propane which has the advantage that it fits into the current RP1 tankage and is around LOX temperature which makes things a lot easier. Further it has a bit over 80% of the ISP advantage or Hydrogen (just a tad lower than Methane in fact) but would probably require about as much engine work as getting a methalox engine up and running so...
The key is injector design and propellant choice and as I noted the concept has been around and on-again-off-again studied during that time. Much as I dislike SCRamjets I have to admit the research into injectors, mixing and combustion have gone a long way to solving many of these issues so that the concept is much more viable than when it first came out. (1950s) Also as I noted the concept was found to be applicable (in thrust augmentation mode since you don't need to address over/under expansion in these engines) to aerospike and plug-nozzle engines.
I did not knew the VentureStar had in-flight stability issues..but yes, looking onto layout, i would not be surprised if VentureStar will flip to fly "tail first" during landing, when payload bay and fuel tanks are empty. NASA engineers should have designed to land her tail-first from the very beginning..
Actually let me be clear, the Venturestar at the end was heavily modified and looked almost nothing like the proposed X33 anymore. It had an external cargo 'bay/pod' and large wings to balance out the engine mass. The X33 itself had dropped in capability from reaching speeds of Mach-8 to "maybe" being capable of hitting Mach-6 and 'instrument' payload had dropped by almost half. Part of the reason the Air Force dropped out so soon was the area of research the X33 could cover wasn't going to be any better than the X-15 if not worse so they would derive no useful data from it.
It is often pointed to the issues with the composite LH2 tank as 'proving' the technology was not there to do SSTO but keep in mind that less than a year after Lockheed-Martin's failure Northrop Grumman delivered a composite LH2 tank to NASA for testing that worked fine. The tank failed for LM because they choose to ignore the sub-contractor they hired to build the tanks and use materials that were understood not to work with LH2. Someone convinced them they could simply 'line' the tanks but this didn't address the actual materials problems.
It depends I think. Though the 'suggestion' from the video's is that the main booster will be nothing more than a "super" Falcon-9 the fact that they are thinking ahead with the ITS stage and are using lifting-body reentry is I think telling. Especially since Musk has historically vehement against any lifting reentry concepts. I highly suspect the "super-Falcon" booster is an artistic placeholder till they do more work on it. A lot depends on where they build both stages as transportation is going to be a major deciding factor. I'd not be surprised to see the booster morph into a more conical vehicle somewhat like the SERV (http://www.astronautix.com/s/serv.html,http://www.pmview.com/spaceodysseytwo/spacelvs/sld034.htm) or Gomersall SSTO concept, (http://www.aerospaceprojectsreview.com/catalog/spacedoc42.jpg) which will be vastly more stable and easier to cover with TPS. The main challenge would be the non-cylindrical tankage and size thereof but I don't suspect that with effort, (and motivation) SpaceX would shy away from the challenge.
Dathi THorfinnsson wrote:
As I've noted before you (I) learn something new here every day
I didn't know the JAXA design used slush-hydrogen, I know that REL's Skylon/SABRE does not but as noted they are not going as far as turning the air liquid but just deep cooling it.Hammerbolt wrote:
Or even the "Closed End Launch Tube" pneumatic concept, (https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20010027422.pdf) depending on how much 'oomph' you need
That's up to Tal Shiar as it's his challenge but the argument could be made that it is a form of 'staging' and detracts from the 'flying into space on its own' portion.
Part of the "draw" as trurle and I discussed above for SSTO is the idea that it would need 'less' infrastructure and operational facilities than a "standard" launch vehicle. Being something that could not only achieve 'aircraft' like operability but similar operations, ("launch from the local airport" and all that) which would directly relate to reduced costs. Rather obviously any major 'construction' such as the rocket sled, MagLev, or such is viewed as violating the KISS principle and the minimum costing no matter how much it might make the actual operations cheaper and/or easier. Which is of course counter-intuitive initially but really no form of transportation exists without significant infrastructure in the modern world and the more sophisticated and 'powerful' the more it requires so the "hope" of limiting the required infrastructure as a cost saving measure is rather forlorn to say the least.
Randy
On a semi-serious side note on having SSTO vehicles I found this "attempted-humor" (much like 'attempted-murder' it may be considered a crime so you have been warned ) post from NASAspaceflight.com that I wrote a bit back. Not sure how some of the link have fared since as I can only check a few on this computer but I'll try it and see.
Enjoy
"Oh hullnuts! While we were all talking up the past we TOTALLY forgot to suggest the DIY method!
http://quantumg.net/mockingbird.pdf
You, a couple of buddy's, your CnC and 3D printer, a pickup truck and your personal 10kg to LEO SSTO! Sure it's PROBABLY going to be a bit on the expensive side and you'll PROBABLY find all sort of governments after your hide after a few launches but that's the FUN part, right?
Hey but that's not all! Switch things up a bit and you can probably milk at least half as much payload through various methods:
(I'm guessing since google is coming up empty no matter which keywords I use Dr. Dunn's alternate SSTO propellant paper is finally gone away )
(Wayback snapshot I think here: file:///C:/Users/1170922146C/Downloads/Dunn%20on%20SSTO%20Propellants.pdf, Yarchive short list here:http://yarchive.net/space/rocket/fuels/fuel_table.html)
Alternate propellants! Sure H2O2/Kerosene is nice and dense and needs no insulation but switch it out for LOX and Cryo-Propane instead! Bit trickier to work with but still well within the DIY range! And you can tell the authorities it's JUST for a barbecue! (Yes LOX cooking IS a thing )
(Note the concept of a "non-cryogenic" propellant SSTO has been suggested before and since Mockingbird as in this paper by Mitchell Burnside Clapp and Maxwell Hunter who's names you may recognize: http://www.erps.org/papers/SSTORwNCP.pdf)
Hey this baby is compact enough you really CAN use some "small" SRBs for it!
(https://engineering.purdue.edu/~propulsi/propulsion/rockets/solids.html)
Sure it's now an "assisted" SSTO but the motors for an AIM-9 or AMRAAM burn out pretty quick so they might fall in a friendly neighbors back-yard. Make space launch a community event!
Hey what about RENE, (Rocket-Engine-Nozzle-Ejector) for some extra "oomph" in your launch! Some re-arranging of parts and more of a "near-SSTO" effort and you can have your very own Mini-Me-NOVA... ER that is Mini-RE-NOVA! As in "reusable NOVA"!
(http://up-ship.com/blog/?p=9462, http://www.dtic.mil/dtic/tr/fulltext/u2/b121965.pdf)
You 'might' have to lose some of the shroud on the way up but maybe not as adding a water or liquid nitrogen intake cooling system might make up for the initial launch inefficiency. Don't forget to put a return address and postage on that main stage though as it will come down quite a ways down range! And then a small 'kick' motor on the payload puts it into orbit! But how to get it back? Well don't fret because in the late 60s a sintered carbon nosecap underwent an HOUR of reentry level heating cooled only by a couple of ounces of water and transpiration cooling and we're WAY more capable today! (And as per usual all my sites with that note are no longer valid, the paper used to be on tethers.com but no luck)
Let's face it the ability to get into loads of trouble at the drop of a launch vehicle is very much in range of today's DIY crowd so let's get out there and get launching!"
Randy
) post from NASAspaceflight.com that I wrote a bit back. Not sure how some of the link have fared since as I can only check a few on this computer but I'll try it and see.Enjoy
"Oh hullnuts! While we were all talking up the past we TOTALLY forgot to suggest the DIY method!
http://quantumg.net/mockingbird.pdf
You, a couple of buddy's, your CnC and 3D printer, a pickup truck and your personal 10kg to LEO SSTO! Sure it's PROBABLY going to be a bit on the expensive side and you'll PROBABLY find all sort of governments after your hide after a few launches but that's the FUN part, right?
Hey but that's not all! Switch things up a bit and you can probably milk at least half as much payload through various methods:
(I'm guessing since google is coming up empty no matter which keywords I use Dr. Dunn's alternate SSTO propellant paper is finally gone away
)(Wayback snapshot I think here: file:///C:/Users/1170922146C/Downloads/Dunn%20on%20SSTO%20Propellants.pdf, Yarchive short list here:http://yarchive.net/space/rocket/fuels/fuel_table.html)
Alternate propellants! Sure H2O2/Kerosene is nice and dense and needs no insulation but switch it out for LOX and Cryo-Propane instead! Bit trickier to work with but still well within the DIY range! And you can tell the authorities it's JUST for a barbecue! (Yes LOX cooking IS a thing
)(Note the concept of a "non-cryogenic" propellant SSTO has been suggested before and since Mockingbird as in this paper by Mitchell Burnside Clapp and Maxwell Hunter who's names you may recognize: http://www.erps.org/papers/SSTORwNCP.pdf)
Hey this baby is compact enough you really CAN use some "small" SRBs for it!
(https://engineering.purdue.edu/~propulsi/propulsion/rockets/solids.html)
Sure it's now an "assisted" SSTO but the motors for an AIM-9 or AMRAAM burn out pretty quick so they might fall in a friendly neighbors back-yard. Make space launch a community event!
Hey what about RENE, (Rocket-Engine-Nozzle-Ejector) for some extra "oomph" in your launch! Some re-arranging of parts and more of a "near-SSTO" effort and you can have your very own Mini-Me-NOVA... ER that is Mini-RE-NOVA! As in "reusable NOVA"!
(http://up-ship.com/blog/?p=9462, http://www.dtic.mil/dtic/tr/fulltext/u2/b121965.pdf)
You 'might' have to lose some of the shroud on the way up but maybe not as adding a water or liquid nitrogen intake cooling system might make up for the initial launch inefficiency. Don't forget to put a return address and postage on that main stage though as it will come down quite a ways down range! And then a small 'kick' motor on the payload puts it into orbit! But how to get it back? Well don't fret because in the late 60s a sintered carbon nosecap underwent an HOUR of reentry level heating cooled only by a couple of ounces of water and transpiration cooling and we're WAY more capable today! (And as per usual all my sites with that note are no longer valid, the paper used to be on tethers.com but no luck)
Let's face it the ability to get into loads of trouble at the drop of a launch vehicle is very much in range of today's DIY crowd so let's get out there and get launching!"
Randy
Some additional information;
2012 paper explaining the basics of the SABRE air-breathing rocket engine concept for the Skylon Spaceplane:
https://info.aiaa.org/tac/PEG/HSABPTC/Public Documents/Skylon Spaceplane.pdf
Yes they have in fact tested a small scale rocket engine that switched between deep-cooled air and LOX during operation so the basic concept works. The rest of the details are debated far and wide but both ESA and AFL agree the basic principles are sound. Most of the 'debate' is not focused on SSTO versus TSTO as an application.
"High Altitude" launch has been studied by NASA and reported here though they use a man-made structure rather than a mountain:
https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20150012328.pdf
Article on spacecraft propellants:
http://www.alternatewars.com/BBOW/Space/Propellants.htm
Not to scare folks, but it IS possible to use a Nuclear Thermal Rocket (NTR) engine system without 'too' much difficulty to propel an SSTO:
https://www.nextbigfuture.com/2015/07/nuclear-thermal-turbo-rocket-with.html
https://arc.aiaa.org/doi/abs/10.2514/6.2015-3958
https://fas.org/sgp/othergov/doe/lanl/lib-www/la-pubs/00384860.pdf
Wikipedia on Air Augmented Rockets and Liquid Air Cycle Engines:
https://en.wikipedia.org/wiki/Air-augmented_rocket
https://en.wikipedia.org/wiki/Liquid_air_cycle_engine
http://astronautix.com/g/gnom.html
The Gomresall SSTO concept which points out many of the issues with a large payload, (1-4 million pounds) launch vehicle. Note this is also designed to be a reusable booster stage for large upper stages such as the S-IVB/LEM/SM/CM combination which is an often overlooked role for reusable vehicles.
https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19680025115.pdf
In other words something like the S-IVB base SSTO being able to put an Apollo capsule and three/four crew into LEO is fine as long as it can be 'upgraded' with additional boosters and/or upper-stages for other missions which makes it more economical, (and useful) in the long run.
Randy
2012 paper explaining the basics of the SABRE air-breathing rocket engine concept for the Skylon Spaceplane:
https://info.aiaa.org/tac/PEG/HSABPTC/Public Documents/Skylon Spaceplane.pdf
Yes they have in fact tested a small scale rocket engine that switched between deep-cooled air and LOX during operation so the basic concept works. The rest of the details are debated far and wide but both ESA and AFL agree the basic principles are sound. Most of the 'debate' is not focused on SSTO versus TSTO as an application.
"High Altitude" launch has been studied by NASA and reported here though they use a man-made structure rather than a mountain:
https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20150012328.pdf
Article on spacecraft propellants:
http://www.alternatewars.com/BBOW/Space/Propellants.htm
Not to scare folks, but it IS possible to use a Nuclear Thermal Rocket (NTR) engine system without 'too' much difficulty to propel an SSTO:
https://www.nextbigfuture.com/2015/07/nuclear-thermal-turbo-rocket-with.html
https://arc.aiaa.org/doi/abs/10.2514/6.2015-3958
https://fas.org/sgp/othergov/doe/lanl/lib-www/la-pubs/00384860.pdf
Wikipedia on Air Augmented Rockets and Liquid Air Cycle Engines:
https://en.wikipedia.org/wiki/Air-augmented_rocket
https://en.wikipedia.org/wiki/Liquid_air_cycle_engine
http://astronautix.com/g/gnom.html
The Gomresall SSTO concept which points out many of the issues with a large payload, (1-4 million pounds) launch vehicle. Note this is also designed to be a reusable booster stage for large upper stages such as the S-IVB/LEM/SM/CM combination which is an often overlooked role for reusable vehicles.
https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19680025115.pdf
In other words something like the S-IVB base SSTO being able to put an Apollo capsule and three/four crew into LEO is fine as long as it can be 'upgraded' with additional boosters and/or upper-stages for other missions which makes it more economical, (and useful) in the long run.
Randy
Ok yup, that makes sense as I'd always heard it was a Navy proposal that kicked off everyone putting out "satellite" proposals. IIRC "World Circling Spaceship" (Air Force) came necxt followed by an Army study. Conversely a few years later it was reversed when the Army put out "Project Horizon" to which the Air Force responded with "LUNEX" but I've heard the Navy released a plan as well but never found details. Unfortunately budget issues, (Truman's budget was military last and of that there wasn't much to go around) stalled on the ongoing research and jacked up the "inter-service rivalry" to the point of outright hostility which was a damn shame. At the time the Army was actually ahead in big, powerful rockets, while the Navy was the most advanced in micro-electronics and the Air Force had the organizational and programmatic skills needed so had they worked together...
Randy
Actually it's one of those "it depends" things as we've tested 600mph 'passive' mag-lev but the main issue is keeping the vehicle on the track
(Not the 'sled' that held on fine the test airframe kept trying to take off even with adjusted to negative lift control surfaces ) Really it depends on what you want the 'booster' to do and current thinking is to use it to boost a ramjet system to start speed which is questionable at best.Eh, not really that bad I think. You can "do" an Orion drive with minimum "fallout" (in all senses of the word) but you really don't want to bring them back as they aren't very efficient for regular traffic. Of course being honest the way we are 'doing' space atm is nothing short of 'dabbling' at best and in truth if we every actually NEED access (say to stop that civilization ending meteor strike) then we'll either die or get Orion religion real quick and that won't be a good thing. (America has proven often enough that "panic" mode gets the job done, yes but never in a sustainable or long-term way)
If we ever figure out a way to do non-nuclear initiated fusion 'bursts' then quite obviously an Orion type drive makes even more sense but there's little plausible justification for an atomic Orion "bang-bang" drive and all the good ones pretty much mean you need it way before you can actually build it. Oddly enough CaribbeanViking's basic system, (Nuclear Verne Gun and Orion Drive spacecraft) it the top contender for a proposed "Planetary Defense" system called "Gabriel"(https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20000097368.pdf) which despite the rather over-the-top nature of the concept is pretty much what we'd "need" given out current lack of space infrastructure and/or lift and delta-V capability.
Randy
Convair NEXUS
It was design as Reusable SSTO for NOVA class mission with 1~2 million Lb. Payload
but you can reduce the size and payload down
a interesting feature is use of low empty mass with large heatshield and use Aerodynamic friction
it not needed parachute, just bunch of retro rockets in heatshield to slow down at touchdown in ocean
were it swims with engines upwards, to be tug back to launch site and refurbish for new launch
It was design as Reusable SSTO for NOVA class mission with 1~2 million Lb. Payload
but you can reduce the size and payload down
a interesting feature is use of low empty mass with large heatshield and use Aerodynamic friction
it not needed parachute, just bunch of retro rockets in heatshield to slow down at touchdown in ocean
were it swims with engines upwards, to be tug back to launch site and refurbish for new launch
Michel Van wrote:
Interesting enough the concept was also 'down' scalable quite handily and a version was suggested to replace the S-iC with a fully recoverable NEXU type stage.
See: http://forums.rocketshoppe.com/showthread.php?t=14863
Other good pics here: http://www.up-ship.com/eAPR/ev3n1.htm
And here: http://www.astronautix.com/n/nexus.html
Several concepts were considered for the "Possible-Apollo Heavy Lift" and/or NOVA programs one of which was the afore mentioned "R/OOST" by Bono from Douglas. One "Air-Augmented" VTVL concept proposed by North American Aviation to the Air Force was an "SSTO" boosted by external burning ramjets which reduced gross-liftoff-mass by as much as 30% and delivering about 500 tons (453mt) to LEO. (http://www.pmview.com/spaceodysseytwo/spacelvs/sld014.htm, Note this design was later resurrected by Rockwell and studied as a candidate for a Heavy Lift Launch Vehicle to support Orbital Solar Power Satellite construction studies in the late 70s) Another was the Martin Company "RE-usable NOVA" or "RENOVA" design was similar in that is used an air-augmentation system, (Air-Augmented-Ejector-Ramjets) to greatly increase initial launch thrust and boost-phase efficiency for a similar, (a little under a million pounds) payload to LEO in a smaller, (193ft high, 70ft in diameter at the widest point in the ejector shroud) size. There was a fully expendable version (payload increase to over 1.3 million pounds) and the design DID expend part of the ejector shroud past about Mach-2-ish to increase the expansion efficiency at high altitude. But like the NEXUS, (and NAA concept which retro-braked to a 'water' landing) the RENOVA didn't require parachutes and used retro-rockets to safety land in the ocean for reuse. (The engines were also more 'protected' due to being shielded by the aero-shroud which had closing doors on the inlets)
(No idea what this is fully but there's this "chapter" on Heavy Lift/Giant LV's worth looking over: file:///C:/Users/1170922146C/Downloads/9783319539393-c1.pdf)
Like most designs (including SeaDragon) these were predicated on the idea that you would in fact soon 'require' a million tons of payload per 'missions' (monthly at best since it would take one or more to 'turn' such beasts) at some point in the future. Really that never came about and is actually unlikely to be either economical or sustainable until smaller and more economical reusable vehicles can actually open up space access.
And that's part of the 'draw' of SSTO in that they are 'supposed' to (hoped to is more accurate) be vehicles that due to their "single-stage" and "aircraft like" operation will be both economically and operationally able to fly to orbit several times a week with minimal processing. But you really need the 'market' before the vehicle OR you need to make, and prove, the economics and utility of such a vehicle up front which has yet to be done. Mostly because while designing and building any LV is not cheap or easy doing so with an SSTO is even MORE so. A point most die-hard SSTO advocates either don't, or more likely deliberately won't, get.
Another point though is that there actually is such a thing as 'too much' or 'too big' a rocket. As most of the studies and concept work we've been tossing about points out, while bigger CAN be better it also comes with a huge amount of increased support, infrastructure, and operational issues that much be included in the overall planning. Transportation from where the rocket is made to where it is launched is a very real consideration. Part of the reason SpaceX is looking to build the BFR/ITS in Texas is the hope they can build a launch port in Brownsville. If not, (which is likely given the noise and other dangers from the launch of such a large vehicle) then they will at least have access to the bay and can ship the stages by water which they could not do on land. And as has been discussed there's a limit as to how 'long' you can make a good sized rocket stage and several advantages to NOT making them the standard "cylinder" shape. (Granted there are advantages but if you look you'll find that a lot of study and wind-tunnel time has been historically spent on finding out that 'odd' shapes are just as cost effective and aerodynamically sound)
I came up with a workable (BotE) concept for a 'squatter' Falcon-9 first stage, initially to lower the overall vehicle height to get around large (and tall) launch support structures. The first version had an internal 'bay' (since some initial calculations done by someone else suggested with some assistance it might be capable of SSTO) by using the same sized jigs to turn out toroidal propellant tanks instead of cylindrical ones. I saved a lot of weight by making the outer "skin" a pressure supported structure, but the need to reinforce and extend the "thrust" structure to support the bay pretty much equaled out. The secondary purpose of the use of toroidal tanks was the standard Falcon-9 Upper Stage actually nestled into the 'bay' with the payload shroud or Dragon-II directly above the first stage.
It looked very much like a more compact version of the Chrysler SERV (http://www.pmview.com/spaceodysseytwo/spacelvs/sld034.htm,https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19730010131_1973010131.pdf) which was on purpose to allow a lower terminal velocity and reduced landing speed. The thing is transportation was difficult as you couldn't 'truck' it as SpaceX does now so the only real option is water transport and it was IIRC correctly a bit of a 'wide-load' for a barge. Landing it ON a barge might have been problematical give its width but on the converse side it can't fall over either I'd suggested simply landing it in the water and towing it back to shore and was "reminded" that rocket engines and sea-water don't mix. To which I pointed out they were tested extensively in the early 60s and found to be remarkably robust and that if SpaceX "can't" do what the engineers half-a-century ago could do then maybe they needed to re-think the business they decided to get into? (Wasn't taken well by SpaceX fans as you might imagine )
Second brush had the toroidal tankage replaced with purpose built, (and shaped) tanks to lose the pressurization system and add propellant volume. Retaining or dropping the 'bay' were actually a wash depending on the desire of the design as it still came out 'marginally' an SSTO, (about 10,000lbs of payload net, maybe) but a better booster.
Which gets me back to the discussion itself in finding a 'justification' for the development and deployment of an SSTO spacecraft. Simply put you need to maintain a credible use for the vehicle and since the average payload per flight is going to arguably be pretty low without a "mega" spacecraft that has issues with being able to haul 'groceries, and people' to a LEO space station. Keep in mind a "million" pounds to LEO sounds great unless you "only" need about 10-to-25Klbs of payload for a "supply-run" mission. The "million" pound spacecraft is going to require the same basic missions costs no matter how much it hauls to orbit so really anything LESS than a 'million' is wasted. On the other hand if you have an SSTO that can "only" really handle 10-20Klbs of 'payload' with little or no room for upgraded or expanded cargo or passengers, (examples would include the Phoenix series, Blackhorse, DC-Y, Roton, Synerjet or the SDIO DC-candidate among others which all have 'fixed' bay or payload area sizes) then you can't provide for other payloads or missions which limit you to a narrow range of applications.
So in the end you don't actually "build" or deploy an SSTO but a booster stage, or stage in general as SpaceX has planned. If it CAN do "SSTO" all well and good but that's not the 'main' point. (Or you at least SAY that's not the main point, Elon had the right of it here ) You build a "booster" stage that just so happened to be 'almost' an SSTO if you only have a payload somewhere around 10,000lbs but it mostly is reusable and can be turned around as easy as possible. At various points you can strap SRB's on and place upper stages as needed to increase payload significantly with as little pain as possible but as it turns out, (oh how 'surprised' you are about this development ) the majority of the time you are either SSTO-ing to a LEO space station to deliver supplies and personnel or mounting a 'standard' second stage to delivery payloads up to three times that to GEO and beyond. Sounds like you got the best of both worlds to me
As always Atomic Rockets has a bunch of information and concepts to waste 'productive-writing' time with the excuse of 'research'
http://www.projectrho.com/public_html/rocket/surfaceorbit.php
Randy
Interesting enough the concept was also 'down' scalable quite handily and a version was suggested to replace the S-iC with a fully recoverable NEXU type stage.
See: http://forums.rocketshoppe.com/showthread.php?t=14863
Other good pics here: http://www.up-ship.com/eAPR/ev3n1.htm
And here: http://www.astronautix.com/n/nexus.html
Several concepts were considered for the "Possible-Apollo Heavy Lift" and/or NOVA programs one of which was the afore mentioned "R/OOST" by Bono from Douglas. One "Air-Augmented" VTVL concept proposed by North American Aviation to the Air Force was an "SSTO" boosted by external burning ramjets which reduced gross-liftoff-mass by as much as 30% and delivering about 500 tons (453mt) to LEO. (http://www.pmview.com/spaceodysseytwo/spacelvs/sld014.htm, Note this design was later resurrected by Rockwell and studied as a candidate for a Heavy Lift Launch Vehicle to support Orbital Solar Power Satellite construction studies in the late 70s) Another was the Martin Company "RE-usable NOVA" or "RENOVA" design was similar in that is used an air-augmentation system, (Air-Augmented-Ejector-Ramjets) to greatly increase initial launch thrust and boost-phase efficiency for a similar, (a little under a million pounds) payload to LEO in a smaller, (193ft high, 70ft in diameter at the widest point in the ejector shroud) size. There was a fully expendable version (payload increase to over 1.3 million pounds) and the design DID expend part of the ejector shroud past about Mach-2-ish to increase the expansion efficiency at high altitude. But like the NEXUS, (and NAA concept which retro-braked to a 'water' landing) the RENOVA didn't require parachutes and used retro-rockets to safety land in the ocean for reuse. (The engines were also more 'protected' due to being shielded by the aero-shroud which had closing doors on the inlets)
(No idea what this is fully but there's this "chapter" on Heavy Lift/Giant LV's worth looking over: file:///C:/Users/1170922146C/Downloads/9783319539393-c1.pdf)
Like most designs (including SeaDragon) these were predicated on the idea that you would in fact soon 'require' a million tons of payload per 'missions' (monthly at best since it would take one or more to 'turn' such beasts) at some point in the future. Really that never came about and is actually unlikely to be either economical or sustainable until smaller and more economical reusable vehicles can actually open up space access.
And that's part of the 'draw' of SSTO in that they are 'supposed' to (hoped to is more accurate) be vehicles that due to their "single-stage" and "aircraft like" operation will be both economically and operationally able to fly to orbit several times a week with minimal processing. But you really need the 'market' before the vehicle OR you need to make, and prove, the economics and utility of such a vehicle up front which has yet to be done. Mostly because while designing and building any LV is not cheap or easy doing so with an SSTO is even MORE so. A point most die-hard SSTO advocates either don't, or more likely deliberately won't, get.
Another point though is that there actually is such a thing as 'too much' or 'too big' a rocket. As most of the studies and concept work we've been tossing about points out, while bigger CAN be better it also comes with a huge amount of increased support, infrastructure, and operational issues that much be included in the overall planning. Transportation from where the rocket is made to where it is launched is a very real consideration. Part of the reason SpaceX is looking to build the BFR/ITS in Texas is the hope they can build a launch port in Brownsville. If not, (which is likely given the noise and other dangers from the launch of such a large vehicle) then they will at least have access to the bay and can ship the stages by water which they could not do on land. And as has been discussed there's a limit as to how 'long' you can make a good sized rocket stage and several advantages to NOT making them the standard "cylinder" shape. (Granted there are advantages but if you look you'll find that a lot of study and wind-tunnel time has been historically spent on finding out that 'odd' shapes are just as cost effective and aerodynamically sound)
I came up with a workable (BotE) concept for a 'squatter' Falcon-9 first stage, initially to lower the overall vehicle height to get around large (and tall) launch support structures. The first version had an internal 'bay' (since some initial calculations done by someone else suggested with some assistance it might be capable of SSTO) by using the same sized jigs to turn out toroidal propellant tanks instead of cylindrical ones. I saved a lot of weight by making the outer "skin" a pressure supported structure, but the need to reinforce and extend the "thrust" structure to support the bay pretty much equaled out. The secondary purpose of the use of toroidal tanks was the standard Falcon-9 Upper Stage actually nestled into the 'bay' with the payload shroud or Dragon-II directly above the first stage.
It looked very much like a more compact version of the Chrysler SERV (http://www.pmview.com/spaceodysseytwo/spacelvs/sld034.htm,https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19730010131_1973010131.pdf) which was on purpose to allow a lower terminal velocity and reduced landing speed. The thing is transportation was difficult as you couldn't 'truck' it as SpaceX does now so the only real option is water transport and it was IIRC correctly a bit of a 'wide-load' for a barge. Landing it ON a barge might have been problematical give its width but on the converse side it can't fall over either
I'd suggested simply landing it in the water and towing it back to shore and was "reminded" that rocket engines and sea-water don't mix. To which I pointed out they were tested extensively in the early 60s and found to be remarkably robust and that if SpaceX "can't" do what the engineers half-a-century ago could do then maybe they needed to re-think the business they decided to get into? (Wasn't taken well by SpaceX fans as you might imagine )Second brush had the toroidal tankage replaced with purpose built, (and shaped) tanks to lose the pressurization system and add propellant volume. Retaining or dropping the 'bay' were actually a wash depending on the desire of the design as it still came out 'marginally' an SSTO, (about 10,000lbs of payload net, maybe) but a better booster.
Which gets me back to the discussion itself in finding a 'justification' for the development and deployment of an SSTO spacecraft. Simply put you need to maintain a credible use for the vehicle and since the average payload per flight is going to arguably be pretty low without a "mega" spacecraft that has issues with being able to haul 'groceries, and people' to a LEO space station. Keep in mind a "million" pounds to LEO sounds great unless you "only" need about 10-to-25Klbs of payload for a "supply-run" mission. The "million" pound spacecraft is going to require the same basic missions costs no matter how much it hauls to orbit so really anything LESS than a 'million' is wasted. On the other hand if you have an SSTO that can "only" really handle 10-20Klbs of 'payload' with little or no room for upgraded or expanded cargo or passengers, (examples would include the Phoenix series, Blackhorse, DC-Y, Roton, Synerjet or the SDIO DC-candidate among others which all have 'fixed' bay or payload area sizes) then you can't provide for other payloads or missions which limit you to a narrow range of applications.
So in the end you don't actually "build" or deploy an SSTO but a booster stage, or stage in general as SpaceX has planned. If it CAN do "SSTO" all well and good but that's not the 'main' point. (Or you at least SAY that's not the main point, Elon had the right of it here
) You build a "booster" stage that just so happened to be 'almost' an SSTO if you only have a payload somewhere around 10,000lbs but it mostly is reusable and can be turned around as easy as possible. At various points you can strap SRB's on and place upper stages as needed to increase payload significantly with as little pain as possible but as it turns out, (oh how 'surprised' you are about this development ) the majority of the time you are either SSTO-ing to a LEO space station to deliver supplies and personnel or mounting a 'standard' second stage to delivery payloads up to three times that to GEO and beyond. Sounds like you got the best of both worlds to me As always Atomic Rockets has a bunch of information and concepts to waste 'productive-writing' time with the excuse of 'research'
http://www.projectrho.com/public_html/rocket/surfaceorbit.php
Randy
trurle
Banned
You missed mass of rocket from the parameters. Actually altitude, mass and optimal launch angle are interlocked - lighter vehicles get more advantage from vertical speed and high altitude. I actually wrote some research papers showing what for ~7kg payload to orbit it is actually makes economic sense to launch from 20km altitude platform, while conventional rockets most economic option is sea level launch.
Sub-cooled Propane-LOX engines have an awful development record. A remember a few designs which failed to utilize it despite the intentions. I suspect it is because sub-cooled propane require very high purity standards to avoid clogging of the pipes, and this purity would be expensive. Any impurity in it is higher-melting than the propane itself. Also, you cannot sub-cool propane by self-evaporation, adding even more complexity to fuel plant.
LE-5B current development roadmap do not feature the return to fuel nozzle injection of LE-5A despite obvious nozzle injection advantage (less back-pressure on pump). It indicate the problem of stable nozzle injection in bell nozzle is not solved yet as in 2018, at least in JAXA.
http://www.rocket.jaxa.jp/engine/le5b/
For plug/aerospike nozzle the geometry allows more flow control and therefore nozzle injection is likely workable, although failure of Firefly Aerospace (which used aerospike concept stolen from Virgin Galactic, who also do not have aerospike engine in road-map currently) may indicate some hidden problem of aerospike design. May be just bad thermal regimes necessitating heavier structure and making aerospike engine disadvantageous compared to bell nozzle, atmosphere or not.
trurle
Banned
Recently i observe increased regulation on H2O2 too, at least in Japan. About 5 years ago, DIY sub-orbital rocket using hybrid engine (plastic/H2O2) has burned out on pad in Hokkaido, and seems the authorities have made a decision to stomp on H2O2 trade afterwards. Now you cannot find on market anything above 9% of H2O2 concentration. Well, may be unrelated of course. Similar problem occurs currently even with acetic acid which is obviously not usable for rockets..You, a couple of buddy's, your CnC and 3D printer, a pickup truck and your personal 10kg to LEO SSTO! Sure it's PROBABLY going to be a bit on the expensive side and you'll PROBABLY find all sort of governments after your hide after a few launches but that's the FUN part, right?
Hey but that's not all! Switch things up a bit and you can probably milk at least half as much payload through various methods:
(I'm guessing since google is coming up empty no matter which keywords I use Dr. Dunn's alternate SSTO propellant paper is finally gone away
(Wayback snapshot I think here: file:///C:/Users/1170922146C/Downloads/Dunn%20on%20SSTO%20Propellants.pdf, Yarchive short list here:http://yarchive.net/space/rocket/fuels/fuel_table.html)
Alternate propellants! Sure H2O2/Kerosene is nice and dense and needs no insulation but switch it out for LOX and Cryo-Propane instead! Bit trickier to work with but still well within the DIY range! And you can tell the authorities it's JUST for a barbecue! (Yes LOX cooking IS a thing
(Note the concept of a "non-cryogenic" propellant SSTO has been suggested before and since Mockingbird as in this paper by Mitchell Burnside Clapp and Maxwell Hunter who's names you may recognize: http://www.erps.org/papers/SSTORwNCP.pdf)
Hey this baby is compact enough you really CAN use some "small" SRBs for it!
Cryo-propane is likely have a purity problems. It is mixed in normal gas tanks with butane for a good reason - these gases are difficult to separate.
I suspect the marinization issues of rocket engines recently is due to the shift of preferred materials. When you replace rhenium of engines for incoloy, and Mg-Al for marginally coated Li-Al alloys, you should not be surprised what your thermal shock and corrosion resistance performance in seawater is decreased. It called evolution deadlock..coming to more and more specialized designs until further improvement is impossible and design from start is required.I'd suggested simply landing it in the water and towing it back to shore and was "reminded" that rocket engines and sea-water don't mix. To which I pointed out they were tested extensively in the early 60s and found to be remarkably robust and that if SpaceX "can't" do what the engineers half-a-century ago could do then maybe they needed to re-think the business they decided to get into? (Wasn't taken well by SpaceX fans as you might imagine
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Ultimately, I think what it boils down to is that if you build a reusable SSTO and sell it to operators, I'll build a booster stage that mounts underneath it with the same technology and twice the design margin, built like a tank, and offer a booster service that quadruples your system's payload and more than halves the $/kg. There's a very rare type of SSTO that can't be made better by being TSTO--a SSTO with barely any margin is a TSTO with oodles, and an SSTO stretched to the limit to make some "awesome" SSTO payload fraction of 1% or so can be turned into a 5%+ GLOW vehicle. Mating two stages doesn't necessarily need to be hard, so just design it not to be. That's the infrastructure/ops problem you need to solve, not stripping the last ten kg of weight out of your heat shield so you have margin for deorbit prop.
That, more than any bias in the industry, is why I think Elon mentions BFS' supposed SSTO capabilityin passing almost as a piece of trivia: it doesn't matter. The things that makes it barely an SSTO are the same thing that make it a kick-butt TSTO upper stage, so why does it matter if it could carry a few tons to LEO by itself?
That, more than any bias in the industry, is why I think Elon mentions BFS' supposed SSTO capabilityin passing almost as a piece of trivia: it doesn't matter. The things that makes it barely an SSTO are the same thing that make it a kick-butt TSTO upper stage, so why does it matter if it could carry a few tons to LEO by itself?
You've been on nasaspaceflight right? It "matters" to people who live-and-breath the mantra that "once we have SSTO space will be blown open as long as no one makes a TSTO out of it first"
Hence when Musk tossed it off THAT was what that segment fixated on.In the end if you have a self limitation (like the payload thing above) then you have a built in disadvantage. This can be a 'non-issue' as long as the overall system you're operating within has the infrastructure and ability to deal with that as a limitation but as far as I can see we've never really managed to make that transition and so a more open capability is indicated.
No mating stages doesn't have to be hard nor does having a 'single' versus multiple stages directly lead to economic or operational savings. That really is "design" stuff and not inherent. Getting people to see that can be... problematic though
Randy
Light is arguably better but tends to be less robust and therefore harder to make reusable. It's trade offs of course and Len Cormier, (https://en.wikipedia.org/wiki/Len_Cormier) among others have long advocated such an approach. As I noted though the basis was air-launch not necessarily specifically though.
Actually I've only know a few engines that even considered it but recall that the RL10 had no issues. (Frankly that damn engine ran on just about anything at one point or another but finding the data is difficult at best) Actually the idea is to use LOX to sub-cool the propane in a heat-exchange where the vast majority of the impurities are filtered and cooled out. But as noted previous LNG tends to win out anyway so other than the fact it will 'fit' in the RP tankage...
I didn't get that they LE-5B was actually trying to use injection and they went with the simpler/simplified engine bell for cost reasons. Aerojet's experiments seemed to work fine but the main reason no one has pursued it is because no one sees a real 'need' for it. Arguably under the current circumstances there IS very little need but it might be different if there was active competition to drive development. (The same could be argued for a LOT of different propulsion systems actually
)There ARE problem with aerospikes as can be read here, (https://vector-launch.com/failure-is-the-seed-of-growth-for-success/) but keep in mind that successful runs of 250K thrust engines were done as well so the problem can be solved with effort. (Something to note in the article is they actually work 'better' in a pressure fed design which is one reason the Air Force experimented with such designs) Firefly 'stole' a number of things from VG but it's notable that VG specifically has stated they are also not actively pursuing those technologies because the Launcher One design was already 'fixed' prior to the employees leaving. Vector among others has done work themselves and feel the design still has merit its just the trade offs are to marginal at this point in time. Once you get into 'reusable' design they make a lot more sense since they can easily operate as both engine and heat shield which given the 'post-boost' dynamics of a typical booster makes things a lot easier. (Note that the small size and budget in the above mentioned LV where particular problems)
Mostly because shipping higher grades of peroxide are a pain and the ability to have on-site distillation systems is so much greater. Oddly enough peroxide has become more 'popular' for bleaching process as it's consider more 'eco-friendy' but production dropped in the late-90s so that its actually harder to get.
P&W stated they 'made' their test cryo-propane for the RL10 by running commercial propane through a heat-exchange with LOX as the coolant. Purity was well over 95% on the first run but they did at least two runs per batch. A quick search says butane will 'chill' out around -0.5c/31f where as the propane liquefies around -42c/-44f. P&W stated they had to hand insert 'liners' into the RL10 cooling channels to run LNG and I'd assume you'd need smaller channels for the denser cryo-propane but I'm not sure as some of Salkhelds "tri-propellant" works suggests you can run both LH2 and Cryo-propane through the same channels. Oddly enough the MAJOR issue with using cryo-propane in any design is that it technically violates a large number of regulations and laws on transport and storage of propane gas which amusingly enough P&W was actually got cited for having propane without the proper 'stenchents' and "impurities" which they duly paid and then got an exemption for. (I've since learned that "ultra-pure" propane exists and is available for use in making computer chips but at the time it wasn't)
Probably but SpaceX has been rather adept at using materials and process' that 'mainline' aerospace industry doesn't so...
It probably had more than a bit to do with the way early engines were manufactured as well since they were generally 'tanks' compared to today's lighter designs. I doubt you couldn't get around the issues though.
Randy
trurle
Banned
Yes, optimization for large thrust/weight is not the sort of design good for versatile use. In my own design studies, i always try to work well into multi-stage, with decent margins on tankage and engine weight.
Regarding SpaceX materials, i remember one their official post in Falcon I era (around ~2009), where they "thanks for NASA collaboration we are fixing issues with our materials selection".