Author Topic: Which is ultimately better, reusable rockets vs. spaceplanes?  (Read 8137 times)

Offline Clueless Idiot

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Which one in the end will allow us to get more tonnage into LEO for the lowest cost? Which one can scale bigger than the other? I'm assuming rockets can scale bigger than a spaceplanes can (since Elon stated that eventually they'll have a rocket that'll dwarf even the ITS).

Offline hkultala

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Depends too much the actual technology involved, so that there cannot be a good general answer for most parts.

Spaceplane practically requires SABRE-style engine to be reasonable.

And it's easier to scale rockets into big size.

Also going to higher than LEO is very hard and inefficient for spaceplanes, but a separate space tug can be used to get payload to higher orbit more effectively.
« Last Edit: 06/02/2017 11:21 AM by hkultala »

Offline Hankelow8

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Spaceplane technology only really works when you are launching a 100 or more satellites a month, not a year.

It will take many years to reach this level, that's when the business plan for spaceplanes works.

Regards reaching higher orbits, that's when space tugs refuelled in orbit by spaceplanes do the job very nicely.

Regretfully Skylon was ahead of its time, this does not mean air-breathing rockets engines are not relevant for today, for the moment more like high-speed cruise in the upper atmosphere, which the Reaction engine is due to start testing an engine in 2019.

 

Offline Clueless Idiot

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Well what about what Virgin Galactic's approach but scaled to way bigger, I mean huge, I mean a much bigger carrier plane and spaceplane, could this ever beat rockets?

Offline john smith 19

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Which one in the end will allow us to get more tonnage into LEO for the lowest cost?
Excellent choice of question. It is indeed all about the money.

One thing your question does leave out is at what size of package does that price apply?

Musk talks of < $1000/lb but that's for a fully used FH to LEO at a flight rate of 4 a year.

Note a rocket needs a lot of infrastructure and a lot of mfg facilities. The difference between a rocket and a spaceplane concept is that a properly designed spaceplane can be launched by multiple countries by multiple owners.   It will probably be capable of self ferry and deliver those prices at much below the fully loaded vehicle a rocket operator needs to give you that price per lb. It's the owners who decide how often any given plane flies but with a rocket the mfg is the owner.  Something that does not happen in any other industry.
"Solids are a branch of fireworks, not rocketry. :-) :-) ", Henry Spencer 1/28/11  Averse to bold? You must be in marketing."It's all in the sequencing" K. Mattingly.  STS-Keeping most of the stakeholders happy most of the time.

Offline john smith 19

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Well what about what Virgin Galactic's approach but scaled to way bigger, I mean huge, I mean a much bigger carrier plane and spaceplane, could this ever beat rockets?
Paul Allen has unveiled Stratolaunch, which is designed to carry a 550 000lb (250tonne) rocket. However AFAIK it's not had its maiden flight yet.
"Solids are a branch of fireworks, not rocketry. :-) :-) ", Henry Spencer 1/28/11  Averse to bold? You must be in marketing."It's all in the sequencing" K. Mattingly.  STS-Keeping most of the stakeholders happy most of the time.

Offline Jarnis

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Wings are silly in space. Rockets provably can land like they always were meant to - on a pillar of flame, tail first. Hence, spaceplanes are pretty silly.

Offline IRobot

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The only advantages of spaceplanes are during take off and landing.
In takeoff because they could potentially land back in case of non catastrophic failure, avoiding loss of payload.
In landing, because it is easier to handle and less stress on structure.

There is also the advantage of flying to a different latitude to match orbital plane.

But... those advantages could be soon gone. Landing seems to be mastered by SpaceX.
And a large ITS-scale vessel could probably still be able to recover from a launch issue.
Orbital plane match can be compensated on rockets by just burning more fuel or handling less weight.

Besides that, spaceplanes are just a mess. Weight distribution throughout the flight is hard to manage. Payload will always be much smaller compared to rockets. Skylon is already 80 meters long for less than 20t of payload. Development is probably much more costly and takes more time.


Offline dror

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My defenition for a spaceplane (what is yours?) is jet engine and wings.
Assuming reusability can reduce the cost of luanch to ~the price of fuel+refurbishment, spaceplanes may set a lower price due to:
less fuel needed with the much higher ISP of jet engines and
less refurbishment needed due to more lofted entry.
« Last Edit: 06/02/2017 01:14 PM by dror »
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Offline Hankelow8

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Wings are silly in space. Rockets provably can land like they always were meant to - on a pillar of flame, tail first. Hence, spaceplanes are pretty silly.

If wings help a spaceplane take off Horizontally and allow a return to base if a problem develops they are not silly.

 If wings help a spaceplane land anywhere it wants on more or less a normal runway it's not silly.

Offline Rocket Science

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Insufficient data at this point...
"The laws of physics are unforgiving"
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Offline JasonAW3

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Sadly, as I am a fan of spaceplanes, I have come to some unfortunate conclusions;

Unless designed as a lifting body, filling every cubic centimeter of volume and making every gram of mass with usable equipment, consumables and fuel, rockets win. 

Even if every bit of a space plane has an alternative use, such as heat sinks for the wings, or extra storage for the landing gear wheel wells, rockets, being purpose built for ONLY one real purpose, still have the advantage.
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Offline Rocket Science

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At this point I don't recall any rocket that has been recovered and re-used returning from an orbital velocity...
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Offline edkyle99

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Which one in the end will allow us to get more tonnage into LEO for the lowest cost? Which one can scale bigger than the other? I'm assuming rockets can scale bigger than a spaceplanes can (since Elon stated that eventually they'll have a rocket that'll dwarf even the ITS).
SpaceX has shown how first stage VTVL might be done (they're still perfecting the idea).  Others are planning to try their hand at the concept.  NASA wanted to do a spaceplane-like flyback first stage for Shuttle, but it cost too much to develop.  It seems that VTVL has won the argument for Stage 1 flight (but don't tell the DARPA XS-1 contractors).

That leaves Stage 2.  TBD!

 - Ed Kyle
« Last Edit: 06/02/2017 02:30 PM by edkyle99 »

Offline IRobot

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My defenition for a spaceplane (what is yours?) is jet engine and wings.
Topic is spaceplane, not airlaunch, so jet engine is not enough.

Assuming reusability can reduce the cost of luanch to ~the price of fuel+refurbishment, spaceplanes may set a lower price due to:
less fuel needed with the much higher ISP of jet engines and
less refurbishment needed due to more lofted entry.
Fuel price is insignificant.
Regarding refurbishment, a spaceplane is always more complex than a rocket, so I don't you can just claim that refurbishment is cheaper.

Offline dror

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My defenition for a spaceplane (what is yours?) is jet engine and wings.
Topic is spaceplane, not airlaunch, so jet engine is not enough.

Assuming reusability can reduce the cost of luanch to ~the price of fuel+refurbishment, spaceplanes may set a lower price due to:
less fuel needed with the much higher ISP of jet engines and
less refurbishment needed due to more lofted entry.
Fuel price is insignificant.
Regarding refurbishment, a spaceplane is always more complex than a rocket, so I don't you can just claim that refurbishment is cheaper.
-Jet - Skylon is a planed spaceplane which uses jet engin for the first part of it's flight. Obviously not enogh but otherwise it's just a rocket.
-Fuel prices - Elon Musks stated the goal of making spaceflight prices to the order of magnitude of fuel prices. He repeats that over and over. Saying that that is insignificant is shortsighted.
-refurb- Jet engines now operate for thousands of hours and rockets dont.
Wings will allow lower G forces on launch and reentry
Being more complex doesn't reflect on refurbishment.
.
« Last Edit: 06/02/2017 07:29 PM by dror »
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Offline rayleighscatter

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Regarding refurbishment, a spaceplane is always more complex than a rocket, so I don't you can just claim that refurbishment is cheaper.
Not necessarily true. If space travel were to become as common as everyone would like, then refurbishing a spaceplane with 1 or 2 larger engines could easily be cheaper than refurbishing a reusable rocket with 9 (or more engines).

Offline KelvinZero

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Just want to say I think the "almost mundane" F9R/ITS/Blue Origin approach has a lot of potential for growth.

Space planes could suddenly find an investor tomorrow, or people could shy away for another half century because the two stage approach just keeps being the place to invest for reliable return and improvement.

I think there is a good chance that by the time someone can prove spaceplanes are ultimately better, it is no longer a race between rockets and spaceplanes anyway. There are lots of other ideas floating around. (Eg ITS upper stage with some sort of rail launcher to put it comfortably into the SSTO range? Not pushing that, just saying it will probably be a different situation that invalidates the comparison)

Offline Gliderflyer

At this point in time I don't think there is enough data on operational RLVs to determine which is better in terms of cost (safety is another story). Both VTVL and HTOL rocket vehicles of (relatively) comparable performance have demonstrated low cost operations with turnaround times less than an hour (although at a small, subsonic scale), and on paper it is easy to scale up either architecture. The issue is that the large amount of unknown variables make it easy to massage the numbers and make a paper rocket in either architecture that is better. Personally I think there are markets for both types of systems, but until we have more data on operational vehicles it is hard to say which is better from a cost perspective.
I tried it at home

Offline john smith 19

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Both VTVL and HTOL rocket vehicles of (relatively) comparable performance have demonstrated low cost operations with turnaround times less than an hour
I'm scratching my head to think what you're talking about?
 The only thing that comes to mind is the Rocket Relay League work that XCOR did but then I'm wondering what the VTOL you would be using for comparison is.

"Solids are a branch of fireworks, not rocketry. :-) :-) ", Henry Spencer 1/28/11  Averse to bold? You must be in marketing."It's all in the sequencing" K. Mattingly.  STS-Keeping most of the stakeholders happy most of the time.

Offline john smith 19

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At this point I don't recall any rocket that has been recovered and re-used returning from an orbital velocity...
True.

In fact 3 designs with wings have demonstrated reentry from full orbital speed, with 2 (Shuttle and X37b) managing repeated reentries.

The difference between reusable rockets and spaceplanes is that we know a spaceplane can do the reentry.
The concepts of Philip Bono in the 60's did not think a conventional rocket aspect ratio could be landed, hence the shorter, wider style of his designs. We now know that, at least for the booster a LV wth this AR can be landed.

We are hoping that SX will manage to find a way to make their upper stage recoverable on the FH but the truth is  Musk has given up on doing this once before, so we'll have to see.

The big difference is that with rockets you hope for full reusability but with spaceplanes you already known it can be done, the problem is in the engines since no one has ever designed a plane with a structure that's less than 10% of fuel weight. OTOH they have designed planes with structures < 26% of fuel, which is viable with something like SABRE. 
"Solids are a branch of fireworks, not rocketry. :-) :-) ", Henry Spencer 1/28/11  Averse to bold? You must be in marketing."It's all in the sequencing" K. Mattingly.  STS-Keeping most of the stakeholders happy most of the time.

Offline Zed_Noir

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Both VTVL and HTOL rocket vehicles of (relatively) comparable performance have demonstrated low cost operations with turnaround times less than an hour
I'm scratching my head to think what you're talking about?
 The only thing that comes to mind is the Rocket Relay League work that XCOR did but then I'm wondering what the VTOL you would be using for comparison is.

Think he is referring to the various Masten Space VTOL test vehicles (Xombie, Xoie, Xaero, Xodiac & Xeus). Also the the various test vehicles from the now defunct Armadillo Aerospace.
 

Offline edkyle99

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The difference between reusable rockets and spaceplanes is that we know a spaceplane can do the reentry.
We know that VTVL has a good chance of working for first stages.  We know that space planes work for reentry.  The next step seems obvious.

 - Ed Kyle

Offline Rocket Science

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At this point I don't recall any rocket that has been recovered and re-used returning from an orbital velocity...
True.

In fact 3 designs with wings have demonstrated reentry from full orbital speed, with 2 (Shuttle and X37b) managing repeated reentries.

The difference between reusable rockets and spaceplanes is that we know a spaceplane can do the reentry.
The concepts of Philip Bono in the 60's did not think a conventional rocket aspect ratio could be landed, hence the shorter, wider style of his designs. We now know that, at least for the booster a LV wth this AR can be landed.

We are hoping that SX will manage to find a way to make their upper stage recoverable on the FH but the truth is  Musk has given up on doing this once before, so we'll have to see.

The big difference is that with rockets you hope for full reusability but with spaceplanes you already known it can be done, the problem is in the engines since no one has ever designed a plane with a structure that's less than 10% of fuel weight. OTOH they have designed planes with structures < 26% of fuel, which is viable with something like SABRE.
I agree with what you say about Shuttle and the X-37B, however I deliberately disregarded them them as since I was referring to a standard rocket design such as the sub-orbital F9R and none has every returned from an orbital velocity so once again we have no apples to apples comparison.  We could compare the X-15 to F9R in terms of re-usable sub-orbital flight with the prior having extensive history... My assumption is that the author is comparing the F9R to the proposed XS-1, but I'll let him clarify if he/she wishes...
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Offline john smith 19

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The difference between reusable rockets and spaceplanes is that we know a spaceplane can do the reentry.
We know that VTVL has a good chance of working for first stages.  We know that space planes work for reentry.  The next step seems obvious.
I'm fairly slow witted so you'll just have to explain it to us.
"Solids are a branch of fireworks, not rocketry. :-) :-) ", Henry Spencer 1/28/11  Averse to bold? You must be in marketing."It's all in the sequencing" K. Mattingly.  STS-Keeping most of the stakeholders happy most of the time.

Online whitelancer64

The difference between reusable rockets and spaceplanes is that we know a spaceplane can do the reentry.
We know that VTVL has a good chance of working for first stages.  We know that space planes work for reentry.  The next step seems obvious.

 - Ed Kyle

Turn the first stage into a spaceplane!
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Offline Jim

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The difference between reusable rockets and spaceplanes is that we know a spaceplane can do the reentry.


Wrong, other structures can reenter

Online whitelancer64

The difference between reusable rockets and spaceplanes is that we know a spaceplane can do the reentry.
We know that VTVL has a good chance of working for first stages.  We know that space planes work for reentry.  The next step seems obvious.

 - Ed Kyle

Or turn the first stage into a spaceplane that also goes into orbit?
"One bit of advice: it is important to view knowledge as sort of a semantic tree -- make sure you understand the fundamental principles, ie the trunk and big branches, before you get into the leaves/details or there is nothing for them to hang on to." - Elon Musk
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Offline TrevorMonty

Combine US and spaceplane eg merge Centuar with X37. Effectively giving useable US with cargo hold. Use LH/LOX  for orbital insertion then storable fuels for in space operations.
For Boeing it maybe way to go, it is well within their capabilities and lot cheaper than doing a reusable booster. If used with Vulcan and SMART then the only expendable part is booster tanks.


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Online Barrie

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The difference between reusable rockets and spaceplanes is that we know a spaceplane can do the reentry.
We know that VTVL has a good chance of working for first stages.  We know that space planes work for reentry.  The next step seems obvious.

 - Ed Kyle

VTVL 1st stage + spaceplane upper stage?

Offline john smith 19

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Wrong, other structures can reenter
Context James, context.  :)

And in this context the key words are  "reusable,"  "orbital" and "velocity."

Which structures did you have in mind that a)Reached orbital velocity and b) Can be reused afterward?
"Solids are a branch of fireworks, not rocketry. :-) :-) ", Henry Spencer 1/28/11  Averse to bold? You must be in marketing."It's all in the sequencing" K. Mattingly.  STS-Keeping most of the stakeholders happy most of the time.

Offline KelvinZero

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Um.. oops. what actually are we talking about here,

Rockets vs air breathers
Cylinders vs lifting bodies
VTOL vs HTOL? (or VTOHL if that is a thing)?

Is the ITS upper stage a lifting body? It looks pretty close.

I had been assuming the spaceplane had significant wings for horizontal landing AND airbreathing for SSTO, really a comparison between something like ITS and something like Skylon, with anything drastically different really a third thing.

Online Eerie

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The difference between reusable rockets and spaceplanes is that we know a spaceplane can do the reentry.
We know that VTVL has a good chance of working for first stages.  We know that space planes work for reentry.  The next step seems obvious.

 - Ed Kyle

Turn the first stage into a spaceplane!

This seems like the opposite of what you would do based on existing technologies. There are reusable first stages rockets (Falcon 9). There were reusable second stage spaceplanes (Shuttle). The logical thing to do is make a reusable second stage spaceplane, and put it on a reusable first stage rocket.  :)
« Last Edit: 06/04/2017 03:41 PM by Eerie »

Offline Dante80

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Spaceplanes can be very interesting. For example, the re-entry regime is much tamer for both cargo and crew. Another example is the ability to take something from orbit (a satellite for example) into your hold and bring it back to Earth.

The rocket equation is pretty mean to SSTOs though. A two stage LV using a spaceplane (say, a re-usable booster with a re-usable spaceplane mounted to it) may in the future be(come) a good competitor to re-usable rocket launch.



Offline TrevorMonty

Spaceplanes can be very interesting. For example, the re-entry regime is much tamer for both cargo and crew. Another example is the ability to take something from orbit (a satellite for example) into your hold and bring it back to Earth.

The rocket equation is pretty mean to SSTOs though. A two stage LV using a spaceplane (say, a re-usable booster with a re-usable spaceplane mounted to it) may in the future be(come) a good competitor to re-usable rocket launch.
HL boosters are size limited due to runways. There is trade between mass of wings and landing speed, smaller wings lighter booster longer runway. The other down side of HL is requirement to RTLS not bad thing as operating costs are lower but also is payload compared to VL landing down range on barge.
HL is well proven and reliable, VL is still in its infancy.
HL require very expensive runway nearby while VL can RTLS requiring only a but flat concrete.


Online QuantumG

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Which structures did you have in mind that a)Reached orbital velocity and b) Can be reused afterward?

Considering what happened to Columbia, I'm not sure why you're advocating for wings. "It's always been done that way" is rarely a good argument, especially if it's only ever been done once. Twice if you want to count the X-37, but Gemini 2 did that first.
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Offline Jim

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Wrong, other structures can reenter
Context James, context.  :)

And in this context the key words are  "reusable,"  "orbital" and "velocity."

Which structures did you have in mind that a)Reached orbital velocity and b) Can be reused afterward?

Any of the Apollo, Gemini or Dragon capsules.

Offline john smith 19

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Wrong, other structures can reenter
Context James, context.  :)

And in this context the key words are  "reusable,"  "orbital" and "velocity."

Which structures did you have in mind that a)Reached orbital velocity and b) Can be reused afterward?

Any of the Apollo, Gemini or Dragon capsules.
Fair point.   :)

I fooled myself by thinking only in terms of vehicle that included most of the hardware to get to orbit IE engines, even if it didn't have the propellant.

To do that with something like those shapes we'd be looking at one of the Bono designs of the 60's or SERV or the candidates for the SRT programme (that produced DC-X) in the late 80's.
Considering what happened to Columbia, I'm not sure why you're advocating for wings. "It's always been done that way" is rarely a good argument, especially if it's only ever been done once. Twice if you want to count the X-37, but Gemini 2 did that first.
X37b has launched 4 times as a design and you forgot Buran.

Actually what I "advocate" is lowering the $/lb cost of access to space in reasonably sized lumps of lift.
something more like 2x the price of a Business class ticket (so you make a reasonable profit)  between 2  destinations 1/2 round the world apart (roughly the "energy cost" to orbit) where you don't have to buy the whole planes seats to get that price.  :(

I'm not a fan of the STS architecture but it did demonstrate
a) A vehicle (the orbiter) could go to and come back from orbit without making radical structural changes (like throwing away a support module).
b) A winged vehicle could do that without needing to be protected inside a shroud to avoid disturbing the rest of the launch architecture too severely IE like the X37b. TBF Buran also demonstrated that on its single flight.

Yes SX have demonstrated recovery and reuse of the first stage.

Yes that's a huge practical achievement. I think that should shift everyone's thinking about what's possible with a VTO TSTO architecture. Time will tell if it actually does.  :(

But conceptually it's no more than recovering the SRB's and refurbishing them.  :(

SX are going to have a go at recovering the upper stage intact on the FH launch. But SX has bauked at doing this once already in 2014 and we don't really have a clue exactly why. I repeat "It's uneconomic" is an effect, not a cause.
"Solids are a branch of fireworks, not rocketry. :-) :-) ", Henry Spencer 1/28/11  Averse to bold? You must be in marketing."It's all in the sequencing" K. Mattingly.  STS-Keeping most of the stakeholders happy most of the time.

Online QuantumG

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and you forgot Buran.

No I didn't. You said hardware that had actually gone to space and been reused. Buran was only flown once.
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Offline Clueless Idiot

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 I meant to include airlaunch as well when I made this thread. So airlaunch where the carrier plane carries a spaceplane or where the carrier plane carries a booster. Say you take the stratolaunch plane and take the second stage off the ITS and put them together, would that be superior to the ITS as a whole?

I mean I just sit here and day dream about the future of spaceflight and we have all these new people on the scene with all their schemes but I keep wondering which one in the end will be the superior way of doing things. I think at this point Elon And Jeff have the right idea with VT/VL rockets but at the same time I dont want to shut the door prematurely on other ideas as well.

Say you were given a 100 billion dollars to revolutionize spaceflight so that one day the average man might be able to book a flight into space. Which route would you take? Would you go down the path Elon and Jeff are taking?

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I meant to include airlaunch as well when I made this thread. So airlaunch where the carrier plane carries a spaceplane or where the carrier plane carries a booster. Say you take the stratolaunch plane and take the second stage off the ITS and put them together, would that be superior to the ITS as a whole?

I mean I just sit here and day dream about the future of spaceflight and we have all these new people on the scene with all their schemes but I keep wondering which one in the end will be the superior way of doing things. I think at this point Elon And Jeff have the right idea with VT/VL rockets but at the same time I dont want to shut the door prematurely on other ideas as well.

Say you were given a 100 billion dollars to revolutionize spaceflight so that one day the average man might be able to book a flight into space. Which route would you take? Would you go down the path Elon and Jeff are taking?

ITS won't fit. It's supposed to be about 12 meters in diameter. That's roughly the distance between the two bodies on the Stratolaunch, but the ground clearance for the payload is about 1/4th that.

That aside, air-launch doesn't give you much of a benefit, yes, you save roughly 10% of the fuel it takes to get to the launch altitude, but really it's simpler to just make the first stage ~10% bigger. The major pluses are you do avoid the costs of having to build or lease a launch site and maintain it, and you have more control over when you can launch.
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Offline envy887

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I meant to include airlaunch as well when I made this thread. So airlaunch where the carrier plane carries a spaceplane or where the carrier plane carries a booster. Say you take the stratolaunch plane and take the second stage off the ITS and put them together, would that be superior to the ITS as a whole?

I mean I just sit here and day dream about the future of spaceflight and we have all these new people on the scene with all their schemes but I keep wondering which one in the end will be the superior way of doing things. I think at this point Elon And Jeff have the right idea with VT/VL rockets but at the same time I dont want to shut the door prematurely on other ideas as well.

Say you were given a 100 billion dollars to revolutionize spaceflight so that one day the average man might be able to book a flight into space. Which route would you take? Would you go down the path Elon and Jeff are taking?

ITS won't fit. It's supposed to be about 12 meters in diameter. That's roughly the distance between the two bodies on the Stratolaunch, but the ground clearance for the payload is about 1/4th that.

That aside, air-launch doesn't give you much of a benefit, yes, you save roughly 10% of the fuel it takes to get to the launch altitude, but really it's simpler to just make the first stage ~10% bigger. The major pluses are you do avoid the costs of having to build or lease a launch site and maintain it, and you have more control over when you can launch.

A significant advantage of air launch is you can be high enough to light vacuum engines, and you don't need a TWR much over 1.

But yes, Stratolaunch would have to be TEN TIMES bigger to lift the ITS upper stage. It could lift a hypothetical Falcon-5 sized vehicle with a single Raptor Vac engine, which with ITS mass fractions would SSTO about 15,000 kg to LEO.

Offline Clueless Idiot

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"But yes, Stratolaunch would have to be TEN TIMES bigger to lift the ITS upper stage."  Lol well that's not practical at all so I guess for the foreseeable future reusable rockets really are the future eh? So Elon and Jeff chose the right route to take it seems

Offline envy887

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"But yes, Stratolaunch would have to be TEN TIMES bigger to lift the ITS upper stage."  Lol well that's not practical at all so I guess for the foreseeable future reusable rockets really are the future eh? So Elon and Jeff chose the right route to take it seems

Well, maybe not. The ITS upper stage is kinda massively gigantically large. It's nearly as heavy by itself as the entire Saturn V stack.

For current normal payloads, Stratolaunch with a custom 2-stage expendable rocket is about the right size. It's even  possible that it could launch a fully reusable SSTO with a payload about the size of Dragon.

Offline Clueless Idiot

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"with a payload about the size of dragon" that's not going to revolutionize the world and get millions of people living in space. Fella's I think the verdict is out on this one, reusable rockets will give you the best bang for your buck, and it's so cool because they're being developed with earnest right now, what a time to be alive.

Offline Jim

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Fella's I think the verdict is out on this one, reusable rockets will give you the best bang for your buck,

No, you can't say that for many reasons, among that spaceplanes have not been disproven.  Also, cost savings from reuse have yet to be realized.

Offline edkyle99

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The difference between reusable rockets and spaceplanes is that we know a spaceplane can do the reentry.
We know that VTVL has a good chance of working for first stages.  We know that space planes work for reentry.  The next step seems obvious.

 - Ed Kyle

VTVL 1st stage + spaceplane upper stage?
Something along those lines.  The upper stage would need to reenter at much higher velocity than the first stage.  The winged reentry method (STS, Buran, X-37B, etc.) is proven.  The problem is that this limits the upper stage to LEO.

 - Ed Kyle
« Last Edit: 06/09/2017 03:19 PM by edkyle99 »

Offline RonM

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The difference between reusable rockets and spaceplanes is that we know a spaceplane can do the reentry.
We know that VTVL has a good chance of working for first stages.  We know that space planes work for reentry.  The next step seems obvious.

 - Ed Kyle

VTVL 1st stage + spaceplane upper stage?
Something along those lines.  The upper stage would need to reenter at much higher velocity than the first stage.  The winged reentry method (STS, Buran, X-37B, etc.) is proven.  The problem is that this limits the upper stage to LEO.

 - Ed Kyle

LEO isn't a problem if it can hand off the payload to a cislunar tug. That will cover everything except the occasional interplanetary mission.

Online Lars-J

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Which is ultimately better, reusable rockets vs. spaceplanes?
« Reply #48 on: 06/11/2017 05:25 PM »
My personal belief is that in the future, spaceplanes will seem like a quaint dead end for aerospace.

The appeal of spaceplanes seems to in my opinion be primarily emotional, and linked to the heavy involvement of test pilots in early space flight. This pilot lobby remained a strong force in NASA before and during the shuttle program.

While it is no doubt possible to build a fully reusable space plane system, it does not appear to be the optimal solution.

Again, this is my opinion and I reserve the right to be proven wrong. :)
« Last Edit: 06/11/2017 05:26 PM by Lars-J »

Offline john smith 19

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The difference between reusable rockets and spaceplanes is that we know a spaceplane can do the reentry.
We know that VTVL has a good chance of working for first stages.  We know that space planes work for reentry.  The next step seems obvious.

 - Ed Kyle

VTVL 1st stage + spaceplane upper stage?
Something along those lines.  The upper stage would need to reenter at much higher velocity than the first stage.  The winged reentry method (STS, Buran, X-37B, etc.) is proven.  The problem is that this limits the upper stage to LEO.

 - Ed Kyle
So you're looking at first stage staging around M10 with a winged 2nd stage to take it and the payload to orbit then coming back.

I've never ceased to be boggled at the concept of VTHL. You need a vehicle that's strong in two major axes and big enough to carry all the propellant.

This has always seemed to me to give you the worst of both worlds. 
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Online Lars-J

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I've never ceased to be boggled at the concept of VTHL. You need a vehicle that's strong in two major axes and big enough to carry all the propellant.

Yes, and that applies to both VTHL and HTHL. (The latter is actually worse, since it needs to sit on the tarmac and lift off fully loaded, whereas VTHL spaceplanes only need to support its near-empty weight while horizontal)

Offline Patchouli

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LEO isn't a problem if it can hand off the payload to a cislunar tug. That will cover everything except the occasional interplanetary mission.

I think in the future this will eventually prove to be the most cost effective solution as this makes full reusability a lot easier.
Kinda like how things were in the Space Odyssey movies.

Though a reusable rocket and a space plane are not mutually exclusive as the latter can be a payload for a reusable rocket and a SSTO one could simply fill a different role.

I think  HTHL type space planes probably will win out for passenger service since they have easier boarding, lower g throughout the mission, and have better abort options etc while VTOL rockets will likely end up carrying most of the large cargo.
On better abort options for example if half the thrust is lost soon after take off on a vehicle like Skylon it doesn't immediately fall out of the sky and can turn around and land.
If something goes wrong early during take off a T+0 failure just kill the thrust and hit the brakes like in this video of an aborted takeoff.

« Last Edit: 06/16/2017 05:59 AM by Patchouli »

Offline john smith 19

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Yes, and that applies to both VTHL and HTHL. (The latter is actually worse, since it needs to sit on the tarmac and lift off fully loaded, whereas VTHL spaceplanes only need to support its near-empty weight while horizontal)
The difference is only 3 VTHL cargo carrying vehicles have ever flow and only one of them had primary thrust operating through its launch axis.

In contrast several thousand HTHL designs have been developed in the 114 yrs since the Wright brothers first flight.
"Solids are a branch of fireworks, not rocketry. :-) :-) ", Henry Spencer 1/28/11  Averse to bold? You must be in marketing."It's all in the sequencing" K. Mattingly.  STS-Keeping most of the stakeholders happy most of the time.

Offline TrevorMonty



LEO isn't a problem if it can hand off the payload to a cislunar tug. That will cover everything except the occasional interplanetary mission.

I think in the future this will eventually prove to be the most cost effective solution as this makes full reusability a lot easier.
Kinda like how things were in the Space Odyssey movies.

If lunar or asteriod supplied fuel to LEO ever becomes cheap enough it could partially refuel a SSTO for earth return. A SSTO becomes lot simplier and lighter if it has amble fuel for retropulsive burn and landing.
Water or cryo fuel can also be used for cooling of heat shield surfaces.
« Last Edit: 06/17/2017 08:04 PM by TrevorMonty »

Online QuantumG

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If lunar or asteriod supplied fuel to LEO ever becomes cheap enough it could partially refuel a SSTO for earth return. A SSTO becomes lot simplier and lighter if it has amble fuel for retropulsive burn and landing.
Water or cryo fuel can also be used for cooling of heat shield surfaces.

... or as I was saying a few years ago, heat shields are going to look pretty antiquated as soon as cheap propellant is available in LEO. At least for any cargo you care about getting to the ground in one piece - especially crew.

BTW, I'd even go beyond extraterrestrial propellant... if you have a reusable tanker that can take fuel to orbit then it makes sense to increase retropropulsion on any crew carrying vehicle that can refuel.
Jeff Bezos has billions to spend on rockets and can go at whatever pace he likes! Wow! What pace is he going at? Well... have you heard of Zeno's paradox?

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