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An SSTO as "God and Robert Heinlein intended".

Posted by: RGClark - Tue Jan 04, 2011 8:37 am
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An SSTO as "God and Robert Heinlein intended". 
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Post Re: An SSTO as "God and Robert Heinlein intended".   Posted on: Sat Jun 18, 2011 3:18 pm
Lourens wrote:
RGClark wrote:
SSTO is not a bad word. It is a very good word. It is my contention that the reason why launch costs are so high, the reason why we don't have passenger access to space as routine as say trans-Pacific flights is that the idea has been promulgated that SSTO is impossible.

So, are you saying that using more than one stage will be much more expensive than SSTO? Why? If you do it like SpaceX, with two very similar stages, the only difference is an additional bulkhead and a separation mechanism. Will that make things significantly more expensive? I don't know where to start calculating on that, but I suspect that with the extra payload that the staging gives you, it may actually lower your cost per pound to orbit.
I'm not saying that SSTO is inherently a bad thing, just that it doesn't look like the best tool for the job.


As Hein said, I agree you could launch more payload to orbit by using staging and the cost per kilo to orbit will be less using staging. BUT you can launch even more at even lower cost per kilo if the individual stages are SSTO's mated bimese or trimese fashion.
To do that, you first have to have to have the SSTO's. As I said this is easy to do if you do what you would normally do for upper stages: use both the most weight optimized stages and the most trajectory optimized engines at the same time.
Now, these SSTO's that you produced can be used singly for launching small payloads and for passenger flights. It is true you could launch more payload by staging. But why use these larger and more expensive rockets if they are not needed? You don't hire a tractor trailer to move a mattress and box spring. You hire a pick-up truck.


Bob Clark

_________________
Single-stage-to-orbit was already shown possible 50 years ago with the Titan II first stage.
Contrary to popular belief, SSTO's in fact are actually easy. Just use the most efficient engines
and stages at the same time, and the result will automatically be SSTO.
Blog: http://exoscientist.blogspot.com


Last edited by RGClark on Sat Jun 18, 2011 8:49 pm, edited 1 time in total.



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Post Re: An SSTO as "God and Robert Heinlein intended".   Posted on: Sat Jun 18, 2011 3:42 pm
Bob,

It seems that you are using the term SSTO in an unconventional way. You are basically saying that an SSTO is a rocket stage with a a high enough ISP and mass fraction such that it's empty carcass could be put into orbit, plus a few extra kilo-grams of payload.

An SSTO normally refers to a reusable vehicle that can achieve orbit and return to earth without shedding any hardware. I suppose if one of your stages carried extra fuel to de-orbit, and had a heat shield and a parachute it would qualify as an SSTO in the traditional sense of the term.

I agree with the goals of higher ISP and higher mass fraction to get the lowest cost. In theory, a stacked multi-stage rocket will always be more efficient than a bimese or trimese rocket, but the difference may be small for large rockets.

Dave

EDIT: I re-read your original post, and you did describe a re-usable rocket stage that would go up to orbit, and return back to earth. So it does appear that you really are talking about SSTO rockets. In the bimese case, the first stage would not require the heat shield that you included in your mass budget.


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Post Re: An SSTO as "God and Robert Heinlein intended".   Posted on: Thu Jun 23, 2011 5:16 pm
RGClark wrote:
This X-37B derived SSTO would be analogous to the winged version of
the X-33 submitted by Rockwell. As I have been arguing switching to
dense propellants allows you to produce a small fully orbital vehicle, where
as the hydrogen fueled version of comparable size could only be suborbital.
It is important to keep in mind the failure of the Lockheed X-33 does
not show that SSTO's are impossible. If you look at the details of
that program you see what failed was the attempt to form conformal,
i.e., non-cylindrically shaped tanks out of composites. However, the
other advanced features were progressing nicely such as the aerospike
engines and the metallic shingle thermal protection.
Then note that the other suborbital X-33 versions proposed by
Rockwell and McDonnell-Douglas would use circular-cross section tanks
that would be easy to produce. So the expectation is they would have
worked, and thus have provided impetus to proceed to the full size orbital versions.
Again note though if these versions had been switched to dense,
hydrocarbon fueled then the original X-33 versions themselves would
have become actually fully orbital.


The original Lockheed version of the X-33 as hydrogen fueled could only be suborbital. By scaling it up twice the VentureStar was supposed to become orbital.
I showed above how a scaled up twice X-37B could become fully orbital. But it is key to note this scaled up, orbit-capable X-37B would still be smaller than the Lockheed X-33 which could not reach orbit as hydrogen fueled. This shows you can get a SSTO vehicle more easily and cheaper as hydrocarbon fueled.
In analogy with the X-33, we might want to get a high Mach suborbital X-37B vehicle first to test the technology before scaling up to the fully orbital version. Then we'll see the X-37B itself can accomplish this as hydrocarbon fueled at a much smaller size and lower cost than the X-33.
In the prior post we saw the twice scaled up X-37B had an internal volume to hold 82,000 kg of kero/LOX. So the X-37B itself can hold 1/8th this at 10,500 kg. (Recall we are filling most of the internal volume with propellant, removing avionics, instrument, and payload bays.)
We'll replace now the low efficiency engine AR-2/3 with a high efficiency kerosene engine. The NK-33 probably will be too heavy at 1,200 kg and also overpowered for the purpose. We'll use the RD-0124. At 480 kg, this weighs 380 kg more than the AR-2/3 but it does have a high sea level and vacuum Isp (but see footnote 1.)
Another possibility might be to use two of the RD-0242-HC. This is much lighter at 120 kg, though of lower thrust so two would be required for a total of 240 kg. It's not clear also if this engine was ever built, being a derivative of an engine originally fueled by hypergolic propellants.
We need now the dry mass of the vehicle. The original NASA X-37 was not to exceed 7,500 lb, 3,400 kg in dry weight. We'll use this value of 3,400 kg for the Air Force's X-37B version. For our purposes it may very well weigh less than this since we don't need the equipment bays and the solar cells. But we'll be using a 380 kg heavier engine so let's make the dry weight 3,800 kg.
We'll use altitude compensation. High performance kerolox engines should be able to get 338.3 s average Isp using altitude compensation. Then our delta-V will be:

338.3*9.8ln(1 + 10,500/3,800) = 4,390 m/s, about Mach 14. This is also well above the required velocity for suborbital flight.


Bob Clark

Footnote 1: I've been informed by email that the RD-0124 is able to get such high sea level and vacuum Isp values, because the values given are from the engine being used in two different configurations. The sea level value is when the engine is being used in a first stage, and has a short nozzle. And the vacuum value is when the vehicle was being used in a upper stage and has a long nozzle. However, by using altitude compensation we should be able to get values close to these.

_________________
Single-stage-to-orbit was already shown possible 50 years ago with the Titan II first stage.
Contrary to popular belief, SSTO's in fact are actually easy. Just use the most efficient engines
and stages at the same time, and the result will automatically be SSTO.
Blog: http://exoscientist.blogspot.com


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Post Re: An SSTO as "God and Robert Heinlein intended".   Posted on: Sun Jun 26, 2011 4:40 am
RGClark wrote:
Lourens wrote:
Bob, what you're saying makes a lot of sense as soon as you replace "SSTO" with "highly efficient". You keep using the term SSTO however, and that misleads your readers, because it makes them think that this is about the disadvantages of staging. At least this reader does...


SSTO is not a bad word. It is a very good word. It is my contention that the reason why launch costs are so high, the reason why we don't have passenger access to space as routine as say trans-Pacific flights is that the idea has been promulgated that SSTO is impossible. That is not the case. In fact it is easy, IF you do it in the right way. The right way is summarized in that one simple sentence at the end of my sig file.
We all know that to get a good payload to space you want a high efficiency engine. And we all know we want to use lightweight structures so the weight savings can go to increased payload. So you would think it would be obvious to use both these ideas to maximize the payload to orbit, right?
And indeed both have been used together - for upper stages. Yet this fundamentally obvious concept still has not been used for first stages. It is my thesis that if you do this then what you wind up with will automatically be SSTO capable. This is true for either kerosene fueled or hydrogen fueled stages.
Part of the misinformation that has been promulgated is that mass ratio for SSTO's is some impossible number. This is false. We've had rocket stages with the required mass ratio's since the 60's, nearly 50 years, both for kerosene and hydrogen fueled. Another part of the misinformation is that it would require some unknown high energy fuel and engine to accomplish. This is false. The required engines have existed since the 70's, nearly 40 years, both for kerosene and hydrogen fueled.
What has NOT been done is to marry the two concepts together for first stages. All you need to do is swap out the low efficiency engines that have been used for the high mass ratio stages and replace them with the high efficiency engines. It really is that simple.
This makes possible small, low cost orbital vehicles that could transport the same number of passengers as the space shuttle, about 7, but would have a comparable cost to a mid-sized business jet, a few tens of millions of dollars.
Then once you have the SSTO's they make your staged vehicles even better because you can carry greater payload when they are used for the individual stages of the multi-staged vehicle.


In disseminating the false dogma that SSTO's are not possible it is sometimes said instead that they are not practical because the payload fraction is so small. Even this is false. And indeed this is just as damaging as making the false statement they are not possible because the statements are often conflated into meaning the same thing. So when those in the industry make the statement they are not "practical", meaning actually they are doable but not economical, this becomes interpreted among many space enthusiasts and even many in the industry as meaning it would require some revolutionary advance to make them possible.
The fact that you can carry significant payload to orbit using SSTO's can be easily confirmed by anyone familiar with the rocket equation. To get a SSTO with significant payload using efficient kerosene engines you need a mass ratio of about 20 to 1. And to get a SSTO with significant payload using efficient hydrogen engines you need a mass ratio of about 10 to 1. Both of these the high mass ratio stages and the high efficiency engines for both kerosene and hydrogen have existed for decades now.
See this list of rocket stages:

Stages Index.
http://www.astronautix.com/stages/index.htm

Among the kerosene-fueled stages you see that several among the Atlas and Delta family have the required mass ratio. However, for the early Atlas stages you have to be aware of the type of staging system they used. They had drop-off booster engines and a main central engine, called the sustainer that continued all the way to orbit. But even when you take this into account you see these highly weight optimized stages had surprisingly high mass ratios.
See for instance the Atlas Agena SLV-3:

Atlas Agena SLV-3 Lox/Kerosene propellant rocket stage. Loaded/empty mass 117,026/2,326 kg. Thrust 386.30 kN. Vacuum specific impulse 316 seconds.
Cost $ : 14.500 million. Semistage: LR89-5. Semistage Thrust (vac): 1,644.960 kN (369,802 lbf). Semistage Thrust (vac): 167,740 kgf. Semistage specific impulse: 290 sec. Semistage Burn time: 120 sec. Semistage specific impulse (sl): 256 sec. Semistage Jettisonable Mass: 3,174 kg (6,997 lb). Semistage- number engines: 2. Semistage: Atlas MA-3.

Status: Out of production.
Gross mass: 117,026 kg (257,998 lb).
Unfuelled mass: 2,326 kg (5,127 lb).
Height: 20.67 m (67.81 ft).
Diameter: 3.05 m (10.00 ft).
Span: 4.90 m (16.00 ft).
Thrust: 386.30 kN (86,844 lbf).
Specific impulse: 316 s.
Specific impulse sea level: 220 s.
Burn time: 265 s.
Number: 140 .

http://www.astronautix.com/stages/atlaslv3.htm

Looking at only the loaded/empty mass you would think this stage had a mass ratio close to 50 to 1. But that is only including the sustainer engine. The more relevant ratio would be when you add in the mass of the booster engines to the dry mass since they are required to lift the vehicle off the pad. These are listed as the jettisonable mass at 3,174 kg. This makes the loaded mass now 117,026 + 3,174 = 120,200 and the dry mass 2,326 + 3,174 = 5,500 kg, for a mass ratio of 21.85.
But this was using the low efficiency engines available in the early 60's. Let's swap these out for the high efficiency NK-33 [1]. The sustainer engine used was the LR89-5 [2] at 720 kg. At 1,220 kg the NK-33 weighs 500 kg more. So removing both the sustainer and booster engines to be replaced by the NK-33 our loaded mass becomes 117,526 kg and the dry mass 2,826 kg, and the mass ratio 41.6 (!).
For the trajectory-averaged Isp, notice this is not just the midpoint between the sea level and vacuum value, since most of the flight to orbit is at high altitude at near vacuum conditions. A problem with doing these payload to orbit estimates is the lack of a simple method for getting the average Isp over the flight for an engine, which inhibits people from doing the calculations to realize SSTO is possible and really isn't that hard. I'll use a guesstimate Ed Kyle uses, who is a frequent contributor to NasaSpaceFlight.com and the operator of the Spacelaunchreport.com site. Kyle takes the average Isp as lying 2/3rds of the way up from the sea level value to the vacuum value [3]. The sea level value of the Isp for the NK-33 is 297 s, and the vacuum value 331 s. Then from this guesstimate the average Isp is 297 + (2/3)(331 - 297) = 319.667, which I'll round to 320 s.
Using this average Isp and a 8,900 m/s delta-V for a flight to orbit, we can lift 4,200 kg to orbit:

320*9.8ln((117,526+4,200)/(2,826+4,200)) = 8,944 m/s.

This is a payload fraction of 3.5%, comparable to that of many multi-stage rockets.
Note in fact that this has a very good value for a ratio that I believe should be regarded as a better measure, i.e., figure of merit, for the efficiency of a orbital vehicle. This is the ratio of the payload to the total dry mass of the vehicle. The reason why this is a good measure is because actually the cost of the propellant is a minor component for the cost of an orbital rocket. The cost is more accurately tracked by the dry mass and the vehicle complexity. Note that SSTO's in not having the complexity of staging are also good on the complexity scale.
For the ratio of the payload to dry mass you see this is greater than 1 for this SSTO. This is important because for every orbital vehicle I looked at, and possibly for every one that has existed, this ratio is going in the other direction: the vehicle dry mass is greater than the payload carried. Often it is much greater. For instance for the space shuttle system, the vehicle dry mass is more than 12 times that of the payload.
This good payload fraction and even better payload to dry mass ratio was just by using the engine in its standard configuration, no altitude compensation. However, for a SSTO you definitely would want to use altitude compensation. Dr. Bruce Dunn in his report "Alternate Propellants for SSTO Launchers" [4] estimates an average Isp of 338.3 s for high performance kerosene engines when using altitude compensation. Then we could lift 5,500 kg to orbit:

338.3*9.8ln((117,526+5,500)/(2,826+5,500)) = 8,928 m/s.

But kerosene is not the most energetic hydrocarbon fuel you could use. Dunn in his report estimates an average Isp of 352 s for methylacetyene using altitude compensation. This would allow a payload of 6,500 kg : 352*9.8ln((117,526+6,500)/(2,826+6,500)) = 8,926 m/s.


Bob Clark


REFERENCES.

1.)NK-33.
http://www.astronautix.com/engines/nk33.htm

2.)LR89-5.
http://www.astronautix.com/engines/lr895.htm

3.)Re: EELV Solutions for VSE.
Reply #269 on: 11/05/2007 09:20 PM
http://forum.nasaspaceflight.com/index. ... #msg208875

4.)Alternate Propellants for SSTO Launchers.
Dr. Bruce Dunn
Adapted from a Presentation at:
Space Access 96
Phoenix Arizona
April 25 - 27, 1996
http://www.dunnspace.com/alternate_ssto_propellants.htm

Disclaimer: the citing of a particular reference should not be construed as an endorsement by the cited authors of the viewpoint expressed herein.

_________________
Single-stage-to-orbit was already shown possible 50 years ago with the Titan II first stage.
Contrary to popular belief, SSTO's in fact are actually easy. Just use the most efficient engines
and stages at the same time, and the result will automatically be SSTO.
Blog: http://exoscientist.blogspot.com


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Post Re: An SSTO as "God and Robert Heinlein intended".   Posted on: Mon Jun 27, 2011 5:19 pm
I argued in this thread that space costs can be reduced by two orders of magnitude in the near term. This will result in large corporations, wealthy individuals, and most national governments possessing their own manned orbital spacecraft.
This clearly will result in some national security concerns that should start being addressed now. I found this report after a web search:

National Security Implications of Inexpensive Space Access.
by William W. Bruner III
"INTRODUCTION
There has been a great deal of recent discussion in the space policy community about the technical challenges of gaining economical and routine access to space. Despite this, there has been little written about the opportunities which exist for the development of new missions for US military space forces. Neither has there been much discussion of the security challenges that any resultant proliferation of access to space may present to the United States and to the established international order. Even the most forward looking space "advocates" in the Department of Defense assume that access to space will continue to be prohibitively expensive and difficult for the foreseeable future, that an American decision not to take advantage of the military potential of space is deterministic for the rest of the world, and that "navigation, communications, and surveillance activities will likely remain the limits of space-based capabilities" for all countries.
Part of this failure to consider the possibilities of a world radically changed by inexpensive access to space is a reaction to the "expectations gap" set up by the gulf between mankind's collective dreams about its future in space and the realities of its achievements so far. The collective public and political mind has been shaped by powerful and convincing fictional images of space activities that we are not likely to see for a hundred years. Real world, but slow moving and silent, pictures of Earth from space taken from small spacecraft with cramped cabins and short mission durations suffer greatly in comparison to images of robust and operable spacecraft spanning the galaxy at faster than light speeds. A century after the Russian Konstantin Tsiolkovsky conceptually solved most of the problems involved in human space flight, over a third of a century since the Soviet Sputnik ushered in the space age, and over a quarter century since America left humanity's first footsteps on another celestial body, many thoughtful and technically literate people are conditioned by historical experience to think of access to space as an expensive enterprise that is technically difficult, dangerous, and the exclusive province of huge government and corporate bureaucracies..."
http://www.fas.org/spp/eprint/bruner.htm


Bob Clark

_________________
Single-stage-to-orbit was already shown possible 50 years ago with the Titan II first stage.
Contrary to popular belief, SSTO's in fact are actually easy. Just use the most efficient engines
and stages at the same time, and the result will automatically be SSTO.
Blog: http://exoscientist.blogspot.com


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Post SSTO would have made possible A. C. Clarke's vision of 2001.   Posted on: Sat Jul 02, 2011 8:38 pm
Space Travel: The Path to Human Immortality?
Space exploration might just be the key to human beings surviving mass genocide, ecocide or omnicide.
July 24, 2009
On December 31st, 1999, National Public Radio interviewed the futurist and science fiction genius Arthur C. Clarke. Since the author had forecast so many of the 20th Century's most fundamental developments, the NPR correspondent asked Clarke if anything had happened in the preceding 100 years that he never could have anticipated. "Yes, absolutely," Clarke replied, without a moment's hesitation. "The one thing I never would have expected is that, after centuries of wonder and imagination and aspiration, we would have gone to the moon ... and then stopped."
http://www.alternet.org/news/141518/spa ... mortality/

I remember thinking when I first saw 2001 as a teenager and could appreciate it more, I thought it was way too optimistic. We could never have huge rotating space stations and passenger flights to orbit and Moon bases and nuclear-powered interplanetary ships by then.
That's what I thought and probably most people familiar with the space program thought that. And I think I recall Clarke saying once that the year 2001 was selected as more a rhetorical, artistic flourish rather than being a prediction, 2001 being the year of the turn of the millennium (no, it was NOT in the year 2000.)
However, I've now come to the conclusion those could indeed have been possible by 2001. I don't mean the alien monolith or the intelligent computer, but the spaceflights shown in the film.
It all comes down to SSTO's. As I argued above these could have led and WILL lead to the price to orbit coming down to the $100 per kilo range. The required lightweight stages existed since the 60's and 70's for kerosene with the Atlas and Delta stages, and for hydrogen with the Saturn V upper stages. And the high efficiency engines from sea level to vacuum have existed since the 70's with the NK-33 for kerosene, and with the SSME for hydrogen.
The kerosene SSTO's could be smaller and cheaper and would make possible small orbital craft in the price range of business jets, at a few tens of millions of dollars. These would be able to carry a few number of passengers/crew, say of the size of the Dragon capsule. But in analogy with history of aircraft these would soon be followed by large passenger craft.
However, the NK-33 was of Russian design, while the required lightweight stages were of American design. But the 70's was the time of detente, with the Apollo-Soyuz mission. With both sides realizing that collaboration would lead to routine passenger spaceflight, it is conceivable that they could have come together to make possible commercial spaceflight.
There is also the fact that for the hydrogen fueled SSTO's, the Americans had both the required lightweight stages and high efficiency engines, though these SSTO's would have been larger and more expensive. So it would have been advantageous for the Russians to share their engine if the American's shared their lightweight stages.
For the space station, many have soured on the idea because of the ISS with the huge cost overruns. But Bigelow is planning on "space hotels" derived from NASA's Transhab concept. These provide large living space at lightweight. At $100 per kilo launch costs we could form large space stations from the Transhabs linked together in modular fashion, financed purely from the tourism interests. Remember the low price to orbit allows many average citizens to pay for the cost to LEO.
The Transhab was developed in the late 90's so it might be questionable that the space station could be built from them by 2001. But remember in the film the space station was in the process of being built. Also, with large numbers of passengers traveling to space it seems likely that inflatable modules would have been thought of earlier to house the large number of tourists who might want a longer stay.
For the extensive Moon base, judging from the Apollo missions it might be thought any flight to the Moon would be hugely expensive. However, Robert Heinlein once said: once you get to LEO you're half way to anywhere in the Solar System. This is due to the delta-V requirements for getting out of the Earth's gravitational well compared to reaching escape velocity.
It is important to note then SSTO's have the capability once refueled in orbit to travel to the Moon, land, and return to Earth on that one fuel load. Because of this there would be a large market for passenger service to the Moon as well. So there would be a commercial justification for Bigelow's Transhab motels to also be transported to the Moon.
Initially the propellant for the fuel depots would have to be lofted from Earth. But we recently found there was water in the permanently shadowed craters on the Moon. Use of this for propellant would reduce the cost to make the flights from LEO to the Moon since the delta-V needed to bring the propellant to LEO from the lunar surface is so much less than that needed to bring it from the Earth's surface to LEO.
This lunar derived propellant could also be placed in depots in lunar orbit and at the Lagrange points. This would make easier flights to the asteroids and the planets. The flights to the asteroids would be especially important for commercial purposes because it is estimated even a small sized asteroid could have trillions of dollars worth of valuable minerals. The availability of such resources would make it financially profitable to develop large bases on the Moon for the sake of the propellant.
Another possible resource was recently discovered on the Moon: uranium. Though further analysis showed the surface abundance to be much less than in Earth mines, it may be that there are localized concentrations just as there are on Earth. Indeed this appears to be the case with some heavy metals such as silver and possibly gold that appear to be concentrated in some polar craters on the Moon.
So even if the uranium is not as abundant as in Earth mines, it may be sufficient to be used for nuclear-powered spacecraft. Then we wouldn't have the problem of large amounts of nuclear material being lofted on rockets on Earth. The physics and engineering of nuclear powered rockets have been understood since the 60's. The main impediment has been the opposition to launching large amounts of radioactive material from Earth into orbit above Earth. Then we very well could have had nuclear-powered spacecraft launching from the Moon for interplanetary missions, especially when you consider the financial incentive provided by minerals in the asteroids of the asteroid belt.


Bob Clark

_________________
Single-stage-to-orbit was already shown possible 50 years ago with the Titan II first stage.
Contrary to popular belief, SSTO's in fact are actually easy. Just use the most efficient engines
and stages at the same time, and the result will automatically be SSTO.
Blog: http://exoscientist.blogspot.com


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Post Re: An SSTO as "God and Robert Heinlein intended".   Posted on: Sun Jul 03, 2011 5:11 pm
You state that SSTOs will bring down the cost per kilogram-to-LEO, but I haven't seen you give any arguments for that. Why would an SSTO be cheaper than a two- or three-stage rocket with the same payload capacity?

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Post Re: An SSTO as "God and Robert Heinlein intended".   Posted on: Wed Jul 06, 2011 2:22 pm
Lourens wrote:
You state that SSTOs will bring down the cost per kilogram-to-LEO, but I haven't seen you give any arguments for that. Why would an SSTO be cheaper than a two- or three-stage rocket with the same payload capacity?


The key reason for the low cost was the reusability. I'm thinking of the SSTO's primarily in regard to manned vehicles. Small, low cost, reusable and privately owned SSTO's could carry small numbers of passengers, at a per vehicle cost in the range of mid-sized business jets. The operational simplicity would favor SSTO's for this purpose.
For carrying cargo and large payloads these SSTO's mated bimese fashion could carry payload at an even lower cost per kilo than standard serially staged multistage vehicles.


Bob Clark

_________________
Single-stage-to-orbit was already shown possible 50 years ago with the Titan II first stage.
Contrary to popular belief, SSTO's in fact are actually easy. Just use the most efficient engines
and stages at the same time, and the result will automatically be SSTO.
Blog: http://exoscientist.blogspot.com


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Post Re: An SSTO as "God and Robert Heinlein intended".   Posted on: Thu Jul 07, 2011 8:50 pm
With a design on "create the future contest", we have acheived the ssto design with methane and lox liquid cheaply.. 1/12 tank assembly with 100000 lbm fuel 7000 lbm rocket assembly weight estimated dry.

The single cylinder in cylinder design is unique and will transport the tank assembly to leo and may be refueled by the falcon 9 heavy...

let us get to mars before i die...30years please

Elon musk where are you?

mark with green computing power


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Post Re: An SSTO as "God and Robert Heinlein intended".   Posted on: Sat Jul 09, 2011 3:18 pm
SSTO refuelable to mars is unique though

Kerosine it would be cold in deeper space

And liquid hydrogen will boil off


So methane ssto is desirable in that context

100000 Lbm fuel. 5000 Lbm rocket and 5000 payload nearly


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Post Re: An SSTO as "God and Robert Heinlein intended".   Posted on: Sat Jul 09, 2011 3:29 pm
Titan ii can be refueled in orbit?

Low cost design ?

Non reinforced tanks. Cheaper

Balance of crippling and buckling to optimize the structure design


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Post Re: An SSTO as "God and Robert Heinlein intended".   Posted on: Sat Jul 09, 2011 5:09 pm
SSTO is fundamentally unworkable. Even thouigh the back-of-envelope amth says yes, just possible it is no good because:
[1] lift-off engine must work at sea level and vacuum. big compromise, and
none of the altitude adapting designs are good enough
[2] aerodynamic loads will require the stage to be heavier and shaped for
withstanding the loads.

So 2 stage makes sense. Have the 1st stage carry the upper stage high enough
for the engine to work as if in vacuum, and enclose the upper stage so it does not contend with aerodynamic loads.

The delta-v for 1st stage need not be much over 1 km/sec for staging to be at 60 km. The Microlauncher entry level launcher, "ML-1", is to have a delta-v of just over 2 km/sec to overcome gravity and aerodynamic loss. The staging altitude is to be 60-70 km, with an upward velocity of 500-800 m/sec.

The upper stage (2 stages in ML case) can then be as light as possible, and if pressurized, use a lower tank and engine pressure than otherwise possible. ML 3rd stage will have an engine pressure of 2-3 atm and 2nd stage about 5 atm. OK in vacuum.

With a 1st stage velocity low enough recovery at the launch site is fairly easy, making that highly re-usable whether the upper stages are.


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Rocket Constructor
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Location: saint louis, MO USA
Post Re: An SSTO as "God and Robert Heinlein intended".   Posted on: Sat Jul 09, 2011 11:59 pm
It had been shown yet that a 12-1 mass ratio with LCH4 could reach LEO

The Merlin rocket can be modified or the NASA XCOR rocket have been tested.


It is feasible


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Rocket Constructor
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Joined: Thu Jul 07, 2011 8:46 pm
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Location: saint louis, MO USA
Post Re: An SSTO as "God and Robert Heinlein intended".   Posted on: Sun Jul 10, 2011 12:23 am
Did you even review the structural innovations on the "create the future"

Website???

Search innovation on the create the future contest site

MSME 1985

Stress and fatigue designer on the x-33 and magnum launch vehicle projects

747 f/a-18 and other airframes


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Space Walker
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Location: Las Vegas NV
Post Re: An SSTO as "God and Robert Heinlein intended".   Posted on: Sun Jul 10, 2011 12:24 am
You missed the 2 points made in my previous post. They are not trivial.

They completely rule out SSTO as an actuality.


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