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#20 by john smith 19 on 03 Jun, 2017 14:19
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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. -
#21 by Zed_Noir on 03 Jun, 2017 14:33
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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.
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#22 by edkyle99 on 03 Jun, 2017 15:20
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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 -
#23 by Rocket Science on 03 Jun, 2017 15:28
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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...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. -
#24 by john smith 19 on 03 Jun, 2017 19:23
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I'm fairly slow witted so you'll just have to explain it to us.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. -
#25 by whitelancer64 on 03 Jun, 2017 19:42
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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!
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#26 by Jim on 03 Jun, 2017 19:43
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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 -
#27 by whitelancer64 on 03 Jun, 2017 19:44
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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
Or turn the first stage into a spaceplane that also goes into orbit?
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#28 by TrevorMonty on 03 Jun, 2017 21:46
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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.
Sent from my SM-G570Y using Tapatalk
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#29 by Barrie on 03 Jun, 2017 22:17
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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? -
#30 by john smith 19 on 04 Jun, 2017 06:25
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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? -
#31 by KelvinZero on 04 Jun, 2017 06:33
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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. -
#32 by Eerie on 04 Jun, 2017 15:40
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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.
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#33 by Dante80 on 04 Jun, 2017 18:25
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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.
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#34 by TrevorMonty on 04 Jun, 2017 21:42
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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.
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.
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 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.
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#35 by QuantumG on 04 Jun, 2017 22:44
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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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#36 by Jim on 05 Jun, 2017 01:01
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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. -
#37 by john smith 19 on 05 Jun, 2017 07:26
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Fair point.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.
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. -
#38 by QuantumG on 05 Jun, 2017 08:32
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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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#39 by Clueless Idiot on 07 Jun, 2017 19:58
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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?
