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Which reusable or SSTO concept from the 1980's-90's would be most promising, if revisited today?


cryogen

Which reusable or SSTO concept from the 1980's-90's would be most promising, if revisited today?  

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  1. 1. Which reusable or SSTO concept from the 1980's-90's would be most promising, if revisited today?

    • X-30 / National Aerospace Plane
    • X-33 / VentureStar
    • DC-I / Delta Clipper
    • MAKS spaceplane
    • Space Shuttle
    • Energia-Buran
    • Other?
    • SSTO isn't useful


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I'm curious what people more informed than me think! Most of these concepts didn't go far, their projects cancelled over either technical or political problems. With 2015 technology, and a well-funded development budget, would any of these be promising today? Or were these all dead ends?

[TABLE=width: 800]

[TR]

[TD]X-30 / National Aerospace Plane[/TD]

[TD]X-33 / VentureStar[/TD]

[/TR]

[TR]

[TD]450px-X-30_NASP_3.jpg[/TD]

[TD]405px-2009VersionX33.JPG[/TD]

[/TR]

[TR]

[TD]

  • Suborbital or SSTO spaceplane
  • Air-breathing scramjet engine
  • Horizontal takeoff & landing

[/TD]

[TD]

  • SSTO spaceplane
  • Linear aerospike engine
  • Composite LH2 tank (controversial)
  • Vertical takeoff, spaceplane landing
  • Metallic heat shield, radiatively cooled

[/TD]

[/TR]

[TR]

[TD]


[/TD]

[TD]


[/TD]

[/TR]

[TR]

[TD]DC-I / Delta Clipper

(pictured is smaller DC-X test vehicle)[/TD]

[TD]MAKS spaceplane (Soviet)[/TD]

[/TR]

[TR]

[TD]405px-DC-XA.jpg[/TD]

[TD]390px-%D0%9C%D0%BD%D0%BE%D0%B3%D0%BE%D1%86%D0%B5%D0%BB%D0%B5%D0%B2%D0%B0%D1%8F_%D0%B0%D0%B2%D0%B8%D0%B0%D1%86%D0%B8%D0%BE%D0%BD%D0%BD%D0%BE-%D0%BA%D0%BE%D1%81%D0%BC%D0%B8%D1%87%D0%B5%D1%81%D0%BA%D0%B0%D1%8F_%D1%81%D0%B8%D1%81%D1%82%D0%B5%D0%BC%D0%B0_-9%D0%90-10485-_%28%D0%9C%D0%90%D0%9A%D0%A1%29.png[/TD]

[/TR]

[TR]

[TD]

  • SSTO rocket
  • Vertical takeoff & landing

[/TD]

[TD]

  • Air-launched SSTO spaceplane
  • Expendable external tank
  • LH2/RP-1/LOX tripropellant

[/TD]

[/TR]

[/TABLE]

(All images from Wikipedia, under Creative-Commons license)

Edited by cryogen
table formatting
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I doubt SSTOs are now much easier than 30 years ago. The ISP of the engines (and thus the possible payload ratio) havent improved (since physics havent changed) and material science hasnt made such a big jump...

But another technical breakthrough will come in the near future, the powered landing of a rocket stage. I think it will be way easier to build a 2 stage reusable rocket that a SSTO, better mass ratio, only one stage need a heatshield etc...

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SSTO's aren't useful :)

MAKS and Energiya-Buran, by the way isn't SSTO in the first place.

Earth is big and it has rather dense atmosphere. You need delta-V to overcome that. This means a lot of fuel and big fuel tanks. Now there is the question - what practical use is in carrying all the dead weight with you? SSTO will always have the smallest payload fraction as compared with MSTO.

Reusable stages/spacecrafts, from the other hand, have future, but let's get the names straight - reusable doesn't mean it flies to orbit without dropping anything. It's just this 'anything' can be used for the second time later.

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I don't think that SSTO makes much sense, however:

- NSP was perfectly impossible, and everybody knew it. It was mainly troll bait to push the USSR into a spending frenzy to bring down its economy (much like the Strategic Defense Initiative).

- X-33 was way too ambitious, and Venture Star was probably not feasible with a significant payload (which is a problem common to all SSTO ideas)

- MAKS/Spiral wasn't SSTO. It was supposed to be airlaunched, but the hypersonic carrier aircraft was (and still is) unrealistic.

- Delta Clipper was probably the most promising, with no silly wings and wheels wasting precious upmass. Again, as an SSTO the payload fraction would have been abysmal, but it might have made a good first stage.

Edited by Nibb31
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- Delta Clipper was probably the most promising, with no silly wings and wheels wasting precious upmass. Again, as an SSTO the payload fraction would have been abysmal, but it might have made a good first stage.

SpaceX agrees.

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I think a SSTO is possible today with small payloads (10-20 T). Will it be economical? That's a bigger question.

Small? With the sole exception of Buran, every payload orbited by anyone since Skylab has been in that class or lower.

- - - Updated - - -

- MAKS/Spiral wasn't SSTO. It was supposed to be airlaunched, but the hypersonic carrier aircraft was (and still is) unrealistic.

MAKS was not Spiral; it was a small hydrolox/kerolox spaceplane with a large drop tank, using the existing An-225 for airlaunch. The tripropellant motor was successfully tested, and the whole thing was probably technically viable. Economic and political viability are different matters entirely, of course, and it still wasn't SSTO.

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Small? With the sole exception of Buran, every payload orbited by anyone since Skylab has been in that class or lower.

I meant not heavy-lift, sorry.

Add that stuff going to GEO will be heavier because the 3rd stage to get it to GEO.

I previous thought about an suborbital spaceplane, it does not go into orbit, it reach the edges of space and deliver an payload who is satellite + upper stage. For anything outside LEO its no point to go into orbit anyway.

This might well be an skylron 0.90 mission profile, its far simpler.

KSP related the only spaceplane who left LKO in KSP was the one I sent to Laythe.

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I don't think that SSTO makes much sense, however:

- NSP was perfectly impossible, and everybody knew it. It was mainly troll bait to push the USSR into a spending frenzy to bring down its economy (much like the Strategic Defense Initiative).

An troll bait who worked pretty much perfectly as in 0.3 m/s correction burn, but that is another story.

- X-33 was way too ambitious, and Venture Star was probably not feasible with a significant payload (which is a problem common to all SSTO ideas)

- MAKS/Spiral wasn't SSTO. It was supposed to be airlaunched, but the hypersonic carrier aircraft was (and still is) unrealistic.

- Delta Clipper was probably the most promising, with no silly wings and wheels wasting precious upmass. Again, as an SSTO the payload fraction would have been abysmal, but it might have made a good first stage.

Else I agree, skylon might work as an SSTO, nothing else using existing technology.

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Reusable is great. Reusable SSTO is better, but impractical with current materials technology.

Reusable boosters and/or first stages are the obvious choice (as SpaceX is quite close to making one work).

Reusable upper stages would be nice as well, but in reality upper stage re-use isn't required currently.

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There are actually a couple of rocket stages that could in theory (and perhaps with a little work) have the performance to be ssto, although they would have terrible payload fractions.

The most notable is the Saturn V second stage (the S-II)

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Reusable is great. Reusable SSTO is better, but impractical with current materials technology.

Reusable boosters and/or first stages are the obvious choice (as SpaceX is quite close to making one work).

Reusable upper stages would be nice as well, but in reality upper stage re-use isn't required currently.

Reusable is a bit of a misnomer.

"Reusable" really implies that all the materials in creation comes back to earth, even if it doesn't crash burn or whatever launching it without a throughout examination / reconstruction where needed results in the same incident as the columbia.

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I only consider SSTO to be viable if we dare to go with nuclear propulsion from ground to orbit.

>900 isp is no joke. Bend the rocket equation to your will. Chemical rockets simply don't have enough energy per mass to get high enough isp for an SSTO with over 8 km/s delta-v.

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NERVA launch is very unlikely to work. Here's Kirk Sorensen's analysis:

http://selenianboondocks.com/2010/06/ssto-ntr-bad/

Simplified: if you have a nuclear thermal SSTO, with an excellent (optimistic) Isp of 900 s, it needs a mass ratio of at least

e^{ (9,200 m/s) / (g * 900 s) } = 2.83

...according to the rocket equation, with 9.2 km/s delta-v to LEO.

(If instead you were to stage an NTR, then the nuclear 1st stage would crash back to earth, which is probably unacceptable. Moreover: there's less economic rationale for having high Isp in a low delta-v first stage -- it'd likely be cheaper to pay the mass penalty and use simpler chemical boosters like RP-1. Exotic, high-Isp propulsion is more useful, the higher up the rocket it's used).

So the propellant fraction ζ would need to be 1 - 1/2.83 = 65%, leaving <35% for engines, structure, and payload combined. So the engine TWR would need be at least 3 just to lift off the ground (rocket TWR > 1), and likely higher than 10 to get any payload to orbit. That's the fatal flaw of NTRs: their TWR is too low. The NERVA rocket had an empty TWR of just under 1. The more performant NTR engine Kirk cites has a TWR of 3, which doesn't lift off the ground either.

This combination of Isp and TWR doesn't add up.

So NTR SSTO even might be technically impossible, at this time. We'd need much higher TWR's: we'd need more compact, lightweight, higher power-density nuclear reactors than can currently be built.

Edited by cryogen
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  • 7 months later...

:D

Spoiler

Please ask more if your qualified.

Any rocket stage can be defined by the perotical burn for instance a chemical rocket engine like S/SM/E switching on then off again such as three times matches the definition for three stages even though the stages remain the vehicle. I have a design based on this principle please see this sound.wave@gm x. dotcom   Wesley 01.

SSTO seem to me as possible if you use S/SM/E (s) and this stage principle which means you can still use three stages like stages in today's rockets but keep them inside. I have done the numbers and they seem indicate a comparable good SSTO vehicle. Thank you. Wesley 01.

Edited by Wesley01
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On 5/30/2015 at 2:52 PM, cryogen said:

NERVA launch is very unlikely to work. Here's Kirk Sorensen's analysis:

http://selenianboondocks.com/2010/06/ssto-ntr-bad/

Simplified: if you have a nuclear thermal SSTO, with an excellent (optimistic) Isp of 900 s, it needs a mass ratio of at least

e^{ (9,200 m/s) / (g * 900 s) } = 2.83

...according to the rocket equation, with 9.2 km/s delta-v to LEO.

(If instead you were to stage an NTR, then the nuclear 1st stage would crash back to earth, which is probably unacceptable. Moreover: there's less economic rationale for having high Isp in a low delta-v first stage -- it'd likely be cheaper to pay the mass penalty and use simpler chemical boosters like RP-1. Exotic, high-Isp propulsion is more useful, the higher up the rocket it's used).

 

So the propellant fraction ζ would need to be 1 - 1/2.83 = 65%, leaving <35% for engines, structure, and payload combined. So the engine TWR would need be at least 3 just to lift off the ground (rocket TWR > 1), and likely higher than 10 to get any payload to orbit. That's the fatal flaw of NTRs: their TWR is too low. The NERVA rocket had an empty TWR of just under 1. The more performant NTR engine Kirk cites has a TWR of 3, which doesn't lift off the ground either.

This combination of Isp and TWR doesn't add up.

So NTR SSTO even might be technically impossible, at this time. We'd need much higher TWR's: we'd need more compact, lightweight, higher power-density nuclear reactors than can currently be built.

I understand what your saying and you can be right But I am getting a different story my figures comes from a different angle as a SSTO is not one stage but can be three stages in one.  Wesley 01 Thank you.

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10 minutes ago, Wesley01 said:

:D

  Hide contents

Please ask more if your qualified.

Any rocket stage can be defined by the perotical burn for instance a chemical rocket engine like S/SM/E switching on then off again such as three times matches the definition for three stages even though the stages remain the vehicle. I have a design based on this principle please see this sound.wave@gm x. dotcom   Wesley 01.

SSTO seem to me as possible if you use S/SM/E (s) and this stage principle which means you can still use three stages like stages in today's rockets but keep them inside. I have done the numbers and they seem indicate a comparable good SSTO vehicle. Thank you. Wesley 01.

Falcon 9 is two stages only, think many of the smaller launchers are 2 stage too. Yes if you are going higher than LEO you will need an circulation burn too but this is always done with upper stage. 

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