Author Topic: Why was there lots of research into space planes and or single-stage-to-orbit  (Read 35943 times)

Offline KelvinZero

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This certainly contradicts the optimism of those suborbital schemes that are effectively two stage with integration in flight ;)
Like SpaceShipTwo? Yeah, it's cool and I'd be glad to see it (or any suborbital tourism) succeed, but I don't think it's a particularly good idea.
I was being a bit facetious, referring to ideas where a sort of upper stage in orbit aerobrakes down to meet a suborbital vehicle and then pushes it to orbit.  8)

Offline Vultur

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It's a correct assumption. There is no turn-key SSTO capability that would be competitive with expendable launch systems.

OK, but that's a much weaker statement than saying it requires breakthroughs. It requires development of the vehicle but not really new technology.

The vehicle isn't "off the shelf"/previously demonstrated but I think all major components needed are, except the landing software which SpaceX is working on right now.

Quote
The low hanging fruit right now is just making the first stage returnable. Even that is very hard to do.

The first few SpaceX attempts failed, but I'd expect it to be routine fairly soon (say in 2 years).

And the problems were with the very end of the landing - I don't think they would have been any worse if it was coming back all the way from orbit (though it would need a TPS).

I was being a bit facetious, referring to ideas where a sort of upper stage in orbit aerobrakes down to meet a suborbital vehicle and then pushes it to orbit.  8)

Ah OK - sorry, I thought you meant SS2 as two stages (carrier aircraft plus spacecraft...)

Yeah I've seen those kinds of ideas, but I don't understand what advantage they are supposed to have over either a plain TSTO or plain SSTO.

Although, the specific rapid-reusability problems I had in mind involved ground operations, and those issues wouldn't apply to that kind of system.

But IMO you might as well go straight to a real SSTO.

Offline nec207

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What technological breakthrough is needed to make space planes and or single-stage-to-orbit (or SSTO possible? What  major problem holding back space planes and or single-stage-to-orbit?

Two different questions a space plane does not need to be single stage to Orbit, see the Space Shuttle, X-37, Dream Chaser and SSTO does not need to be an space plane(however being some type of airplane could be helpful in terms of being capable of generating lift.)

SSTO is possible now, but the problem is SSTO while carrying a practical payload and most SSTO concepts require re usability. The issue is with materials. Mathematically it is possible to get to orbit using chemical rocket in an single stage. It is just that the materials we have to build the SSTO out of are too heavy to allow this concept to work with current technology but technology changes. Lighter weight structures and heat shields would allow this concept to work as well as engines like the sabre(which could allow you to get much higher and faster without using on board oxygen and can double as both an jet and rocket engine.).  We can build an SSTO now, but it won't be able to haul much into orbit and it won't be reusable. It simply would not be practical at the moment.

Space planes are better suited than capsules for certain things. The return to the capsule is being driven by different dynamics. For Orion and CST-100 reusing Apollo's shape saves research and development(esp. for Orion). For Space X, wings don't fit the company philosophy. For Dream Chaser "wings" allow much more selection of places to land as well as reduced G-forces on the crew.

In terms of BEO. Space planes could find an role as an mars mission as the earth reentry vehicle. There is debate on wither on not an the crew can survive the G-forces from that fast an reentry in an capsule. For lunar missions there was an interesting concept floated of using an version of dream chaser as an lunar craft or using the shuttle's cargo bay to haul up an capsule and crew and docking it with an pre-positioned stage launched by Titan in LEO.  While wings can be useless in space, they can be handy at the end of the mission.

But that is what I said before that no one replied to me on here. Under Bush he decided to go to the moon and canceled all research into cheap affordable reusable craft for getting people and payload into space.

Going to moon in SSTO or space plane would been way more of a technology and emerging problem than getting into space. It would of taken longer and cost way more money into R&D.

Under President Obama he pushed for going to Mars and an Asteroid. Going in a SSTO or space plane to Mars and an Asteroid would of been even more of technology and emerging problem and cost very yes very large number of R&D.

Gong into space is in SSTO or space plane is a technology and emerging problem and going to moon and beyond would been even more of a technology and emerging and lots of R&D.

And politics look at short term goals not long term goals. The public was losing interest into space so after  the shuttle accident the politicians used it as a PR to get people more into space and public support.

Selling people the political PR to get NASA support. And going into space and building a space station was been there and done that . Time to go beyond low orbit. That us canceled all research into cheap affordable reusable craft for getting people and payload into space and push beyond low orbit to get public support.

Offline nec207

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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.

Don't have to!!!! NASA is going to spend trillions of money to send people to moon and mars and after 4 to 8 trips it be like a the Apollo program.

The public and politicians will say we spent trillions and trillions of money going to the moon and mars and we can no longer support trips to moon or mars or moon or mars base.

Than they will say that spend money into cheap space access and cheap affordable reusable craft to the moon and mars and beyond!! But by that time it will be the year 2050!!!



Offline john smith 19

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"Big dumb whatever" works in a lot of areas, but in aerospace, you have the brutal exponential rocket equation. If you try "big dumb" you necessarily have to have several stages. It's still possible, though at the expense of needing more stages, which means more expense. And you still have a much higher GLOW for the same payload, which means a bigger launch pad (or launching at sea, with all the complications involved).

"Big dumb" may be a valid first stage design criteria, I'm not sure. But for the upper stage, where your mass overhead directly eats into your payload, you are likely to be much better off with the typical approach of trying to lightweight the crap out of everything and picking the highest performing materials possible, especially for an RLV (which can be reused). Making everything out of silver or something just as expensive clearly makes sense (obviously silver isn't that strong for its mass, just using an example).
Before commenting further I suggest you read what the originator of the idea has to say for himself on the subject.

http://www.sfo.org/library/schnitt/

You should note his goal was minimum cost design. Being "big" and (relatively) "dumb" was the result.

Incidentally Russian rockets, which have racked up 100s of launches without failure, follow some of the MCD principles, with a safety factor of 2, rather than the 1.25  of US ELV's (and SF of 1.5 for human rated ELV's).
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 Nilof

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Incidentally Russian rockets, which have racked up 100s of launches without failure, follow some of the MCD principles, with a safety factor of 2, rather than the 1.25  of US ELV's (and SF of 1.5 for human rated ELV's).

...And the Russians do this by having lots of stages, with 4-5 stages to GEO being rather common. The path they have followed is making staging extremely simple and reliable and integration easy even with a lot of stages.
« Last Edit: 11/23/2015 05:54 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 edkyle99

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Back to the X-37B example. 

Assume first a spaceplane orbital mass at 5-ish tonnes (like X-37B). 

Assume the spaceplane can carry enough propellant to perform its own LEO insertion burn (perhaps 1,500 m/s delta-v) with an ascent  propellant mass fraction of 0.4 (spaceplane GLOW of 8 tonnes).

Assume spaceplane propulsion ISP = 320 seconds.

Assume a 500 kg payload on the spaceplane.

Assume a single booster stage, powered by two SLS-style RS-25 engines, 430 seconds average ISP for the trip. 

If the booster can carry 282 tonnes of usable propellant with a gross liftoff weight of 302 tonnes, LEO can be achieved.  We're pushing the mass-fraction envelope, hard.  With the spaceplane, total liftoff mass is 310-ish tonnes.

All of this is very big IF, of course.

The result of this attempt to use one big stage results in - one big stage.  It would be more than one-third larger (volume-wise) than a Delta 4 CBC and about 40% as large as a Shuttle External Tank - and it would only put 5.3 tonnes in LEO x 28.5 deg and only 500 kg of usable payload.  That's Minotaur 1 class.

 - Ed Kyle
« Last Edit: 11/23/2015 05:21 pm by edkyle99 »

Offline Robotbeat

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"Big dumb whatever" works in a lot of areas, but in aerospace, you have the brutal exponential rocket equation. If you try "big dumb" you necessarily have to have several stages. It's still possible, though at the expense of needing more stages, which means more expense. And you still have a much higher GLOW for the same payload, which means a bigger launch pad (or launching at sea, with all the complications involved).

"Big dumb" may be a valid first stage design criteria, I'm not sure. But for the upper stage, where your mass overhead directly eats into your payload, you are likely to be much better off with the typical approach of trying to lightweight the crap out of everything and picking the highest performing materials possible, especially for an RLV (which can be reused). Making everything out of silver or something just as expensive clearly makes sense (obviously silver isn't that strong for its mass, just using an example).
Before commenting further I suggest you read what the originator of the idea has to say for himself on the subject.

http://www.sfo.org/library/schnitt/

You should note his goal was minimum cost design. Being "big" and (relatively) "dumb" was the result.

Incidentally Russian rockets, which have racked up 100s of launches without failure, follow some of the MCD principles, with a safety factor of 2, rather than the 1.25  of US ELV's (and SF of 1.5 for human rated ELV's).
Oh trust me, I'm familiar with the idea.
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Offline the_other_Doug

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I will note that Russian rockets have racked up hundreds of launches, but not without failures.  Look up the failure rates of Proton and Soyuz launchers, among others, sometime.  There have been some rather high-profile failures over the past few years.
-Doug  (With my shield, not yet upon it)

Offline Proponent

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"Big dumb whatever" works in a lot of areas, but in aerospace, you have the brutal exponential rocket equation. If you try "big dumb" you necessarily have to have several stages. It's still possible, though at the expense of needing more stages, which means more expense. And you still have a much higher GLOW for the same payload, which means a bigger launch pad (or launching at sea, with all the complications involved).

"Big dumb" may be a valid first stage design criteria, I'm not sure. But for the upper stage, where your mass overhead directly eats into your payload, you are likely to be much better off with the typical approach of trying to lightweight the crap out of everything and picking the highest performing materials possible, especially for an RLV (which can be reused). Making everything out of silver or something just as expensive clearly makes sense (obviously silver isn't that strong for its mass, just using an example).
Before commenting further I suggest you read what the originator of the idea has to say for himself on the subject.

http://www.sfo.org/library/schnitt/

You should note his goal was minimum cost design. Being "big" and (relatively) "dumb" was the result.

To quote Arthur Schnitt himself, "The MCD analysis showed that first stages, as part of a multi-stage expendable SLV, should be the least sophisticated; and that the optimum degree of hardware sophistication increases with each successive, upper stage."
« Last Edit: 11/24/2015 12:00 pm by Proponent »

Offline john smith 19

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To quote Arthur Schnitt himself, "The MCD analysis showed that first stages, as part of a multi-stage expendable SLV, should be the least sophisticated; and that the optimum degree of hardware sophistication increases with each successive, upper stage."
Exactly.

Save the cutting edge, wafer thin margin  tech for the uppermost stage.

Which sort of flips SX's plans on their head.
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 savuporo

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BTW, Musk just claimed that F9 first stage is a SSTO
Orion - the first and only manned not-too-deep-space craft

Offline HMXHMX

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BTW, Musk just claimed that F9 first stage is a SSTO

Of course it is.  If it has a PMF >0.95, it can't help but be able to fly to the reference LEO orbit.  And with sequential engine shutdown it can certainly stay below 4-5 Gs, unlike another first stage (the Titan II) which is also an expendable SSTO.

Offline KelvinZero

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BTW, Musk just claimed that F9 first stage is a SSTO
Hey, you know that dumbish-idea of some massive infrastructure that catapults the rocket off the launch pad, saving the first few seconds of slowly building up speed which apparently uses a fair bit of fuel..

..well I was just thinking: Suppose you had a single stage to orbit that you were happy with, apart from negligible payload to orbit, then at that point how attractive does that extra boost at the launch pad look in terms of payload to orbit? What is the mathematical relationship roughly?

Offline savuporo

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Hey, you know that dumbish-idea of some massive infrastructure that catapults the rocket off the launch pad, saving the first few seconds of slowly building up speed which apparently uses a fair bit of fuel..
No end to these ideas, huh. Including building a launch pad at Volcán Cayambe
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Offline Robotbeat

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To quote Arthur Schnitt himself, "The MCD analysis showed that first stages, as part of a multi-stage expendable SLV, should be the least sophisticated; and that the optimum degree of hardware sophistication increases with each successive, upper stage."
Exactly.

Save the cutting edge, wafer thin margin  tech for the uppermost stage.
...
Which is, in fact, exactly what I said.
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Offline Robotbeat

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To quote Arthur Schnitt himself, "The MCD analysis showed that first stages, as part of a multi-stage expendable SLV, should be the least sophisticated; and that the optimum degree of hardware sophistication increases with each successive, upper stage."
Exactly.

Save the cutting edge, wafer thin margin  tech for the uppermost stage.

Which sort of flips SX's plans on their head.
If you have a fully, rapidly reusable first stage, then yeah, Minimum Cost Design would lead you to use cutting edge tech on the first stage while relaxing the cutting-edge-ness on the (expendable) upper stage.

Different assumptions give you different conclusions.
« Last Edit: 11/25/2015 12:40 am by Robotbeat »
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Offline john smith 19

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To quote Arthur Schnitt himself, "The MCD analysis showed that first stages, as part of a multi-stage expendable SLV, should be the least sophisticated; and that the optimum degree of hardware sophistication increases with each successive, upper stage."
Exactly.

Save the cutting edge, wafer thin margin  tech for the uppermost stage.

Which sort of flips SX's plans on their head.
If you have a fully, rapidly reusable first stage, then yeah, Minimum Cost Design would lead you to use cutting edge tech on the first stage while relaxing the cutting-edge-ness on the (expendable) upper stage.

Different assumptions give you different conclusions.
I suggest you read his articles again.

His point is to do with what NASA have called the "exchange rates" IE 1 unit of extra mass means what do you lose from final payload.

For the 1st stage not much. So go big (which is pretty cheap), go simple (to keep it cheap) and go expendable.

But this was back when avionics were heavy and (very) expensive. So that changes things a bit. Likewise piston pumps are much simpler to make but Whitehead's team reckons the crossover point was only about 5000lbs, so we get back to turbopumps. OTOH CAD driving CNC changes the economics of that problem quite a lot.

But his conclusion still says "pay mass to avoid cost."

Trouble is that means you leave all the reusability in the upper stage, as well as the return from orbit issues.

And just a reminder SX still does not have a reusable first stage. Currently I'm thinking it'll be available before Q417.
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 HMXHMX

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To quote Arthur Schnitt himself, "The MCD analysis showed that first stages, as part of a multi-stage expendable SLV, should be the least sophisticated; and that the optimum degree of hardware sophistication increases with each successive, upper stage."
Exactly.

Save the cutting edge, wafer thin margin  tech for the uppermost stage.

Which sort of flips SX's plans on their head.
If you have a fully, rapidly reusable first stage, then yeah, Minimum Cost Design would lead you to use cutting edge tech on the first stage while relaxing the cutting-edge-ness on the (expendable) upper stage.

Different assumptions give you different conclusions.
I suggest you read his articles again.

His point is to do with what NASA have called the "exchange rates" IE 1 unit of extra mass means what do you lose from final payload.

For the 1st stage not much. So go big (which is pretty cheap), go simple (to keep it cheap) and go expendable.

But this was back when avionics were heavy and (very) expensive. So that changes things a bit. Likewise piston pumps are much simpler to make but Whitehead's team reckons the crossover point was only about 5000lbs, so we get back to turbopumps. OTOH CAD driving CNC changes the economics of that problem quite a lot.

But his conclusion still says "pay mass to avoid cost."

Trouble is that means you leave all the reusability in the upper stage, as well as the return from orbit issues.

And just a reminder SX still does not have a reusable first stage. Currently I'm thinking it'll be available before Q417.

I'd slightly rephrase "pay mass to avoid cost" to "burn propellant to avoid cost" since propellant is the cheapest mass to buy and use aboard a lunch vehicle.
« Last Edit: 11/26/2015 05:09 am by HMXHMX »

Offline Robotbeat

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To quote Arthur Schnitt himself, "The MCD analysis showed that first stages, as part of a multi-stage expendable SLV, should be the least sophisticated; and that the optimum degree of hardware sophistication increases with each successive, upper stage."
Exactly.

Save the cutting edge, wafer thin margin  tech for the uppermost stage.

Which sort of flips SX's plans on their head.
If you have a fully, rapidly reusable first stage, then yeah, Minimum Cost Design would lead you to use cutting edge tech on the first stage while relaxing the cutting-edge-ness on the (expendable) upper stage.

Different assumptions give you different conclusions.
I suggest you read his articles again.

His point is to do with what NASA have called the "exchange rates" IE 1 unit of extra mass means what do you lose from final payload.

For the 1st stage not much. So go big (which is pretty cheap), go simple (to keep it cheap) and go expendable.

But this was back when avionics were heavy and (very) expensive. So that changes things a bit. Likewise piston pumps are much simpler to make but Whitehead's team reckons the crossover point was only about 5000lbs, so we get back to turbopumps. OTOH CAD driving CNC changes the economics of that problem quite a lot.

But his conclusion still says "pay mass to avoid cost."

Trouble is that means you leave all the reusability in the upper stage, as well as the return from orbit issues.

And just a reminder SX still does not have a reusable first stage. Currently I'm thinking it'll be available before Q417.
And I suggest you read my post again. I said "f you have a fully, rapidly reusable first stage..."
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

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