Author Topic: Why was there lots of research into space planes and or single-stage-to-orbit  (Read 35940 times)

Offline Archibald

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All I'll say is that it is mass fraction, not Isp, that needs to be improved, and additionally, if one develops an SSTO and if falls short of expectations, it can be salvaged as an operational system by various expedients such as a zero-stage, air-launching, sled-launching, recoverable strap-ons, etc.  If you start your design process with a goal of two-stages, you'll never magically reach SSTO capability.  But if you start with an SSTO goal, you might get there by incremental improvements that come from learning due to higher flight rates with time.

Would that the human race could have evolved on a 0.9 G planet, so that these arguments might be moot.

Goddam big Earth with its huge gravity pull !!

How about suborbital refueling ?
http://selenianboondocks.com/2009/11/random-thoughtsorbital-access-methodologies-vii-air-launched-glideforward-tsto-with-exo-atmospheric-suborbital-refueling/

As John Goff said

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I think the case of exoatmospheric suborbital refueling will likewise be one of those crazy things that we wonder how we ever lived without.
;D
Han shot first and Gwynne Shotwell !

Offline JasonAW3

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     Almost wish I could organize a superkickstarter to get billionaires to fund an independant research group to actually develope a working Lifting Body SSTO system.
My God!  It's full of universes!

Offline john smith 19

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All I'll say is that it is mass fraction, not Isp, that needs to be improved,
Careful  here. There is certainly true for vertical SSTO, where if the thrust does not exceed the lift it simply won't take off. I don't think the situation is so clear cut (or investigated) for horizontal takeoff.
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and additionally, if one develops an SSTO and if falls short of expectations, it can be salvaged as an operational system by various expedients such as a zero-stage, air-launching, sled-launching, recoverable strap-ons, etc.
Absolutely true.
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If you start your design process with a goal of two-stages, you'll never magically reach SSTO capability.  But if you start with an SSTO goal, you might get there by incremental improvements that come from learning due to higher flight rates with time.
Definitely.
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Would that the human race could have evolved on a 0.9 G planet, so that these arguments might be moot.  :)
IE where 1g is about 8.83m/s^2
MCT ITS BFR SS. The worlds first Methane fueled FFSC engined CFRP SS structure A380 sized aerospaceplane tail sitter capable of Earth & Mars atmospheric flight.First flight to Mars by end of 2022 TBC. T&C apply. Trust nothing. Run your own #s "Extraordinary claims require extraordinary proof" R. Simberg."Competitve" means cheaper ¬cheap SCramjet proposed 1956. First +ve thrust 2004. US R&D spend to date > $10Bn. #deployed designs. Zero.

Offline NovaSilisko

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I'm just thankful we didn't evolve on a planet with 25% more gravity. We'd be, in short, quite screwed.

I do agree Earth has too much, though. We should do something about it.
« Last Edit: 11/17/2015 06:43 pm by NovaSilisko »

Offline A_M_Swallow

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{snip}
Would that the human race could have evolved on a 0.9 G planet, so that these arguments might be moot.  :)

There is a 0.376 g planet ready and waiting.

Offline Proponent

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Was there any particular factor that lead to the resurgence of interest in SSTO in the mid-1990s?  I'm guessing it was just a desire to take a second crack at cheap Earth-to-orbit transportation, after the failure of the Shuttle.  But was there some other trigger that I'm missing?

Offline JamesG123

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Was there any particular factor that lead to the resurgence of interest in SSTO in the mid-1990s?  I'm guessing it was just a desire to take a second crack at cheap Earth-to-orbit transportation, after the failure of the Shuttle.  But was there some other trigger that I'm missing?

There was money available. The Reagan/Bush Administrations were interested in new space ideas (SDI, New Frontiers),  and Congress was willing to cough up some (but not enough) money.

Offline rayleighscatter

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X33 seems to have been captured within NASA by the "Let's get lots of new tech developed" arm. This is a very bad idea for an X plane project.
It's the very intent of the X programs though. With a few rare exceptions, research is the main intent, not a sustaining program.

Offline HMXHMX

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Was there any particular factor that lead to the resurgence of interest in SSTO in the mid-1990s?  I'm guessing it was just a desire to take a second crack at cheap Earth-to-orbit transportation, after the failure of the Shuttle.  But was there some other trigger that I'm missing?

Yeah, I am afraid I was the factor (for rocket-powered SSTO, not NASP).  I convinced Max Hunter, and together we convinced Jerry Pournelle and Danny Graham, and they convinced the Vice President, and one thing led to another... :(

Max used to tell me it was easy to start a riot but hard to control it once started.  Man, was he ever right.
« Last Edit: 11/17/2015 11:21 pm by HMXHMX »

Offline HMXHMX

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{snip}
Would that the human race could have evolved on a 0.9 G planet, so that these arguments might be moot.  :)

There is a 0.376 g planet ready and waiting.

That we perhaps can't live on (in my view) due specifically to the lower gravity.  But that's the subject of a different forum posting, which generated more heat than light...so best stay away from it here!

Offline Robotbeat

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A lot of that "heat" was my fault.

HMXHMX, what are you up to? BTW, do you have a nice summary document of DC-Y/DC-X or any of the other high-mass-fraction vehicles you worked on?
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

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Offline edkyle99

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Why was there lots of research into space planes and or single-stage-to-orbit (or SSTO ) in the 90's?

But we are not doing it today? Why is that?
Because it costs far less to develop smaller, lighter, more capable expendable launch vehicles.

 - Ed Kyle

Offline Vultur

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I think SSTO is entirely achievable with current technology - the Mercury Atlas was dang close in the early 60s, and its engines had unimpressive Isp and TWR by modern standards.

A propane/LOX (probably the best compromise between density and Isp - it's only a tiny bit less Isp than methane with much greater density) VTVL SSTO would probably work fine and not even be much of a stretch.

Offline HMXHMX

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A lot of that "heat" was my fault.

HMXHMX, what are you up to? BTW, do you have a nice summary document of DC-Y/DC-X or any of the other high-mass-fraction vehicles you worked on?

Unfortunately, as usual, I can't comment on my current work except to say it isn't SSTO.  Close, though.  But in response to the document request, I can only offer up an ancient paper:

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

Note especially the appendix:

http://www.spacefuture.com/archive/a_single_stage_to_orbit_thought_experiment.shtml

I probably should finish up the book draft I started around 1992 (Single Stage: The 30 Year Quest for the Reusable Spaceship).  It's only half done since I put it on the shelf about 1993 or so, and I have no idea if I'll ever re-write it, since now it needs to be renamed "...The 60 Year Quest..."  :)

Offline john smith 19

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X33 seems to have been captured within NASA by the "Let's get lots of new tech developed" arm. This is a very bad idea for an X plane project.
It's the very intent of the X programs though. With a few rare exceptions, research is the main intent, not a sustaining program.
Yes and no.

Successful X programmes have a very small (typically 1) goal. X1 was "Exceed M1 in level flight" to the X15 "Cruise at high enough Mach for long enough that the whole airframe "soaks" and we can see how it changes" (not the wording, but the key idea). Then use that data to populate the design handbooks for the next generation of vehicles.

Successful X programmes did this with the simplest possible approach. The simplest way to exceed M1? Stick a big rocket in back. Otherwise you're stuck with not only a tough task (which should be why your running one in the first place) but the need for a lot of additional stuff to a)Work and b)Work at the performance level needed for vehicle.

This multiplies the risk of failure.
X33 supposed goal was to demonstrate SSTO but it also needed

The lifting body shape to work (ultimately never tried in a crewed vehicle before the Dream Chase prototype flew) .
The complex shaped LH2 composite tank (although it turned out an aluminum tank with the same mass either was available or was within the design capability of the team)
The linear plug nozzle engine, when no plug nozzle of any description had flown and which get a major redesign during the programme, making the vehicle even more rear heavy, and hence complex to control, like the Shuttle.
The (lightweight) metallic TPS.

LM would say all of this was essential to making SSTO but neither of the other thought so. It was however all very exciting technology and if it all worked together the design would have been a triumph. And it all needed to work as you could not replace most of the major parts without a huge redesign of the rest.

But none of it worked (or got to the stage it could be tested) to where a flight vehicle was flown.

The only thing that worked perfectly about LM's bid was their ability to win it in the first place.  :(
MCT ITS BFR SS. The worlds first Methane fueled FFSC engined CFRP SS structure A380 sized aerospaceplane tail sitter capable of Earth & Mars atmospheric flight.First flight to Mars by end of 2022 TBC. T&C apply. Trust nothing. Run your own #s "Extraordinary claims require extraordinary proof" R. Simberg."Competitve" means cheaper ¬cheap SCramjet proposed 1956. First +ve thrust 2004. US R&D spend to date > $10Bn. #deployed designs. Zero.

Offline Elmar Moelzer

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Unfortunately, as usual, I can't comment on my current work except to say it isn't SSTO.  Close, though. 
Oh, I cant wait to hear what that is! Glad to hear that you are back in action, Gary!

Offline Nilof

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One other approach that hasn't been mentioned yet is beamed power propulsion, which escape dynamics is working on. It is still at Robert Goddard levels of TRL and scale compared to chemical propulsion, but it is great to see someone finally taking on the task of maturing the technology to some extent and actually building hardware rather than present powerpoint slides. The key complete unknown here is what engine thrust to weight ratios are possible with such designs.
« Last Edit: 11/19/2015 07:59 pm by Nilof »
For a variable Isp spacecraft running at constant power and constant acceleration, the mass ratio is linear in delta-v.   Δv = ve0(MR-1). Or equivalently: Δv = vef PMF. Also, this is energy-optimal for a fixed delta-v and mass ratio.

Offline TrevorMonty

One other approach that hasn't been mentioned yet is beamed power propulsion, which escape dynamics is working on. It is still at Robert Goddard levels of TRL and scale compared to chemical propulsion, but it is great to see someone finally taking on the task of maturing the technology to some extent. The key complete unknown here is what engine thrust to weight ratios are possible with such designs.

The beamed power approach trades a large LV for large expensive ground facilities. I don't think it will work out financially but the idea has merit for lunar landers. The power could be beamed from Solar Power Satellite, which could also be used for beaming power to lunar facilities the other 99.99% of the time.

Offline NovaSilisko

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One other approach that hasn't been mentioned yet is beamed power propulsion, which escape dynamics is working on. It is still at Robert Goddard levels of TRL and scale compared to chemical propulsion, but it is great to see someone finally taking on the task of maturing the technology to some extent. The key complete unknown here is what engine thrust to weight ratios are possible with such designs.

Now you've got me wondering what it would have been like if Goddard had a website and blog.  ;)

Offline A_M_Swallow

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One other approach that hasn't been mentioned yet is beamed power propulsion, which escape dynamics is working on. It is still at Robert Goddard levels of TRL and scale compared to chemical propulsion, but it is great to see someone finally taking on the task of maturing the technology to some extent. The key complete unknown here is what engine thrust to weight ratios are possible with such designs.

The beamed power approach trades a large LV for large expensive ground facilities. I don't think it will work out financially but the idea has merit for lunar landers. The power could be beamed from Solar Power Satellite, which could also be used for beaming power to lunar facilities the other 99.99% of the time.

Different materials have different boiling points, specific heat capacity and latent heat of vaporization. Can lunar and Mars regolith be used as propellant in beamed power landers? Something that can just be scooped up and crushed makes for a cheap ISRU fuel.

Alternatively water and carbon dioxide could be used.

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