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[New] Spaceplane Discussion Thread


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3 minutes ago, DeadJohn said:

IMO, the shuttle had a worthy goal: reusable body and main engines with rapid turnaround for lots of launches. In practice, the shuttle didn't reach that goal because it needed too much maintenance between flights, and even if maintenance issues were fully solved there wasn't enough demand for placing big payloads into space.

The space shuttle ended up being a very expensive way to place payloads and crews into orbit, despite the partial reusability. It was too big and too expensive to use as an ISS ferry.

The shuttle could do some neat things like servicing Hubble, but if NASA didn't have a shuttle it would have figured out another way to do that job. Hubble could have been launch on a large disposable rocket and serviced by whatever other launch systems evolved. NASA and Space X are looking at that now: https://www.nasa.gov/feature/goddard/2022/nasa-spacex-to-study-hubble-telescope-reboost-possibility

We learned a lot from the shuttle. The heat tile problems led to improved methods for the X-37 robot spaceplane, Space X Dragon, etc.

Agreed, the shuttle was a cool concept, but it didn't go well in execution.

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1 hour ago, Rutabaga22 said:

What are the opinions about the space shuttle around here?

It was dangerous and wasteful. But it looked cool and was still reasonably capable.

I don’t think it was bad, it did do things like build the ISS. But it could have been done better, and alternatives to it with more safety and versatility existed.

If I sounded hostile to it in earlier posts, it is because I think it is important to recognize it had problems and that mistakes were made. NASA PR tends to treat everything as this great fantastic journey that was destined to happen this way and was an incredible faultless accomplishment, and I dislike that.

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The coolest spaceplane I know is the Serenity from Firefly.

Unfortunately, having two engines on a swivel each opposite the center of mass gives you massive amounts of roll control, but no pitch control (and yaw control only by differential thrust). So that's not as pretty as you might think.

The "ultimate" spaceplane (to me) is one that can re-enter, land vertically in a horizontal attitude, take off vertically in a horizontal attitude, deliver cargo or pick up passengers, fly to somewhere else, then land vertically once again. That vertical takeoff means it doesn't need a prepared runway, and the self-ferry capability is what will make that so useful.

 

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17 minutes ago, SunlitZelkova said:

NASA PR tends to treat everything as this great fantastic journey that was destined to happen this way and was an incredible faultless accomplishment, and I dislike that.

You mean them making it so the majority of space merchandise shuttle themed?

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3 hours ago, Rutabaga22 said:

You mean them making it so the majority of space merchandise shuttle themed?

Saying things like “we decided to focus on low Earth orbit and now we are going back to the Moon”.

The original intention was to do stuff in LEO and more experimental deep space stuff via Apollo Applications. Then it was the space shuttle and a space station, but Nixon nixed the station. Then it was Space Station Freedom and maybe a return to the Moon in the early decades of the 21st century, but Challenger happened and no one cared about the station enough to get it built. Then came SEI which was like the 80s station-Moon plan 2.0 but no one cared to fund it yet again. Finally Freedom died and became the ISS, but Columbia happened. That gave us Constellation- yet another program, after SEI, to claim all was well in American space exploration and we were taking the next glorious step. Obviously it didn’t work out and here we are again.

This time around is different though, mainly because of the advent of commercial space.

I think it is important to recognize the problems of the past. The inherent design flaws of the Shuttle, the contractor shenanigans that led to Apollo 1, and the complacency with the heat shield that led to Columbia are rarely mentioned in NASA PR.

This attitude is how we end up with ICPS bathing astronauts in the Van Allen belts however many times over.

———

Perhaps the post-Columbia post-Shuttle proposal (what ended up as Constellation) could have been better if the Moon people had looked at the history of the ISS and studied it to understand how difficult it is to pitch a project to NASA. Instead Constellation was more or less Apollo 2.0, which doomed it from the start.

Instead of informing the public why they failed us with proposal after proposal wasting valuable funds and time, the entire history of NASA is glossed over as an all-innovative, almost sacred path towards the stars.

Now I suppose I’m sure the average space fan and even the public is well aware of these errors. But NASA doesn’t seem to be, and that is concerning.

Its not entirely their fault though. Pork farmers are equally part of the problem.

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16 hours ago, sevenperforce said:

The "ultimate" spaceplane (to me) is one that can re-enter, land vertically in a horizontal attitude, take off vertically in a horizontal attitude, deliver cargo or pick up passengers, fly to somewhere else, then land vertically once again.

Another note -- we like to yammer a lot about SSTOs, but for science fiction purposes the more useful vehicle is the SSFO -- Single Stage From Orbit. You really want a vehicle which can leave low planetary orbit, re-enter and land, perhaps ferry itself between a couple of destinations, and then return to orbit again, taking off and landing vertically each time but remaining in a horizontal attitude throughout.

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14 hours ago, SunlitZelkova said:

Perhaps the post-Columbia post-Shuttle proposal (what ended up as Constellation) could have been better if the Moon people had looked at the history of the ISS and studied it to understand how difficult it is to pitch a project to NASA. Instead Constellation was more or less Apollo 2.0, which doomed it from the start.

Instead of informing the public why they failed us with proposal after proposal wasting valuable funds and time, the entire history of NASA is glossed over as an all-innovative, almost sacred path towards the stars.

Now I suppose I’m sure the average space fan and even the public is well aware of these errors. But NASA doesn’t seem to be, and that is concerning.

Its not entirely their fault though. Pork farmers are equally part of the problem.

Which is a bit odd, because the Shuttle was a political triumph for NASA.  Between covering all the politicians pet projects and the sunk cost fallacy being what it is, they managed nearly 200 manned missions with the thing.  On the downside, getting that political triumph required a set of requirements that lead the engineers to create what we now know as "the Shuttle", and even with hindsight several threads worth of attempts have yet to make a better Shuttle that fits all the requirements needed at design time (one of the big ones was dropped late, but they effectively had to cover it).

You'd think they'd learn from the success.  But more likely they didn't understand why Apollo was canceled.

2 hours ago, sevenperforce said:

Another note -- we like to yammer a lot about SSTOs, but for science fiction purposes the more useful vehicle is the SSFO -- Single Stage From Orbit. You really want a vehicle which can leave low planetary orbit, re-enter and land, perhaps ferry itself between a couple of destinations, and then return to orbit again, taking off and landing vertically each time but remaining in a horizontal attitude throughout.

So not only magic Isp but magic engines.  Because either those  engines rotate or are duplicated and still don't overdo the mass issues of SSTO.  And of course all those SF vehicles somehow don't abuse the landing pad (Kirk landed his Klingon Bird of Prey in a 20th century park, Stormtroopers stood nearby the Millennium Falcon when we first saw it take off) even with a TWR>>1.  On the other hand, Arthur C. Clarke was right about the definition of "magic" and such things might well be possible well before the 2200s.

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17 minutes ago, wumpus said:
2 hours ago, sevenperforce said:

Another note -- we like to yammer a lot about SSTOs, but for science fiction purposes the more useful vehicle is the SSFO -- Single Stage From Orbit. You really want a vehicle which can leave low planetary orbit, re-enter and land, perhaps ferry itself between a couple of destinations, and then return to orbit again, taking off and landing vertically each time but remaining in a horizontal attitude throughout.

So not only magic Isp but magic engines.  Because either those  engines rotate or are duplicated and still don't overdo the mass issues of SSTO.  And of course all those SF vehicles somehow don't abuse the landing pad (Kirk landed his Klingon Bird of Prey in a 20th century park, Stormtroopers stood nearby the Millennium Falcon when we first saw it take off) even with a TWR>>1.  On the other hand, Arthur C. Clarke was right about the definition of "magic" and such things might well be possible well before the 2200s.

Oh yes, magic indeed.

Of course, the slower the exhaust is moving, the less dangerous it is to be in the vicinity. And fortunately the ground has a bunch of thick air around it which tends to be useful for such things. 

I've always wanted to come up with a realizable way that you could have air intakes with extremely high bypass in one direction and progressively lower bypass in the other direction so that you wouldn't need variable geometry for an airbreather. Just rotate the nacelle based on speed and altitude.

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The main benefits of a plane layout for a spacecraft compared to anything else are:

1) Larger area per unit mass and higher L/D means peak loading on the heat shield is reduced, allowing for non-ablative solutions (easier reuse). This also aids larger downmass.

2) Non-propulsive landing. Substantially safer than relying on engines 

3) Use of existing landing infrastructure (airports). Land almost anywhere if necessary.

4) Landing on wheels is a relatively clean landing method. Theoretically it shouldn't take much to turn around a landed space plane.

So if you want to bring a lot of mass back to earth, don't care too much about where you land, and want the vehicle to be rapidly reusable, a spaceplane is a fair design bet.

The Space Shuttle never really brought down anything particularly heavy, in practice only ever landed at three facilities, and other design decisions compromised points 2 and 4.

If you don't mind landing propulsively at the launch site, wings are pretty superfluous.

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On 10/6/2022 at 5:51 AM, RCgothic said:

2) Non-propulsive landing. Substantially safer than relying on engines 

True. However, there are situations where engines are more fault-tolerant than wings; for example, fewer weather constraints. There were numerous shuttle missions where re-entry and landing had to be delayed due to inclement weather at the landing site. In contrast, propulsive landings (at least of the SpaceX variety) couldn’t care less what the weather is like.

If Shuttle had possessed the ability to abort or divert landings via onboard jet engines as originally imagined, this would have been ameliorated a little.

On 10/6/2022 at 5:51 AM, RCgothic said:

3) Use of existing landing infrastructure (airports). Land almost anywhere if necessary.

Yeah, the propulsively-landed horizontally-flown spaceship of science fiction is super cool but it is really only needed on an undeveloped world. 

On 10/6/2022 at 5:51 AM, RCgothic said:

So if you want to bring a lot of mass back to earth, don't care too much about where you land, and want the vehicle to be rapidly reusable, a spaceplane is a fair design bet.

The Space Shuttle never really brought down anything particularly heavy, in practice only ever landed at three facilities, and other design decisions compromised points 2 and 4.

So far we have not really had reasons to bring significant downmass. If we had a colony on another planet with an atmosphere similar to Earth’s, that would be a meaningful consideration, but that doesn’t appear to be on the horizon in this solar system. 

On 10/6/2022 at 5:51 AM, RCgothic said:

If you don't mind landing propulsively at the launch site, wings are pretty superfluous.

Even Shuttle had oversized wings for ordinary landing because of crossrange reqs. The Air Force wanted to be able to do polar dogleg launches with a landing at the launch site after a single orbit, so it needed insane amounts of glide. Without those requirements I believe the Shuttle would have been closer to a pure lifting body design. 

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Remember, we're in KSP :)

I've read somewhere on the forums that engine plates that have something attached to their bottom stack node shield from drag what's inside and whatever is attached to their top snack node, including fairings.

This way, we can have (almost) drag-free SSTOs.

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4 hours ago, sevenperforce said:

Even Shuttle had oversized wings for ordinary landing because of crossrange reqs. The Air Force wanted to be able to do polar dogleg launches with a landing at the launch site after a single orbit, so it needed insane amounts of glide. Without those requirements I believe the Shuttle would have been closer to a pure lifting body design. 

Isn't your "insane amount of glide" still a 1:1 glide coefficient?  One of the reasons that spaceplanes really aren't an option on Earth.

 

4 hours ago, Nazalassa said:

Remember, we're in KSP :)

I've read somewhere on the forums that engine plates that have something attached to their bottom stack node shield from drag what's inside and whatever is attached to their top snack node, including fairings.

This way, we can have (almost) drag-free SSTOs.

Sounds suspiciously like the "old aero model".  That was when every part created drag, regardless of where it was.  Or a bug.  More likely, a bug.

But Kerbin is so small and has such a  low orbital velocity that normal supersonic aircraft engines can take you to SSTOSSTO isn't impossible thanks to physics.   SSTO is just completely impractical on Earth.  The only crafts ever to land humans on the Moon were SSTO.

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  • 2 weeks later...
On 10/8/2022 at 7:14 PM, Nazalassa said:

we can have (almost) drag-free SSTOs.

The worst thing is that it actually works.
Now, atmosheric heating in KSP is directly related to the ship's drag coefficient, so --
that means that a dragless contraption, whatever it is, won't overheat for atmospheric heating. I didn't test it for heating due to be close to the Kerbol, but I don't think it shields from the heat from Kerbol.

Edited by Nazalassa
Stupid keyboard ate the letters, re-eaten.
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On 10/8/2022 at 5:23 PM, wumpus said:

Isn't your "insane amount of glide" still a 1:1 glide coefficient?

Yes, the hypersonic glide ratio was 1:1 which was "insane" in the sense that it was about double the maximum achievable hypersonic glide ratio of a capsule-based design.

The Shuttle could also do a 2:1 glide ratio in supersonic flight and a 4.5:1 glide ratio in subsonic flight, although the subsonic regime was too short to get appreciable crossrange during that period.

A capsule-based design would not have been able to re-enter and glide back to the launch site in a once-around polar orbit.

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The thing about the Shuttle that most people in this forum seem to constantly forget is that it was its own space station. If it had been designed just as a ferry for people and a limited amount of cargo to a permanent space station, it would have been a lot smaller and cheaper.

It also was built with 1970s technology.

It seems silly to say in the 2020s that the Shuttle taught us that spaceplanes are not a good option. That's kind of like saying in 1950 that the Wright Flyer taught us that airplanes should be made of wood.

It also was hugely instrumental in assembling the ISS. It's not clear the ISS as it exists today could have been built without the Shuttle.

X-37-style spaceplanes appear to be completely viable alternatives to capsules, as far as I can tell. They have some advantages and disadvantages in terms of safety and reliability. I particularly see them as likely more safe and reliable than propulsive landing.

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This is how i would go about creating a Reusable Rocket.

SpaceX Falcon 9 booster + some dream chaser size thing

Should work

 

A spaceplane is trickier. Let's just say that this plane is designed to ferry people to an orbital space station. 

We will have 4 J58's. With all our rocket fuel, plus passengers, we might just top out at Mach 2.7ish with modern technology. 

Thats only about 750m/s-800m/s

Orbital velocity is approx. 7500m/s.

Our one advantage is that we re zooming really really high. About 90,000 feet. Much less drag up here, and also, our rocket engines are more efficient. A Merlin Vacuum has ISP of 348. Because our SR-71 is much bigger to accommodate the fuel for this engine, it is much heavier. A Merlin 1D vacuum produces about 96,000kg of thrust. With all the jet fuel burnt, out craft ways about 50 tones. With only 40 tones of fuel, that's about half of a full 2cd stage. We need a better engine. Or two of them. With more fuel and a larger aircraft. 

It might work. Im not sure how well though...

 

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4 hours ago, TKMK said:

SpaceX Falcon 9 booster + some dream chaser size thing

Dream chaser is a capsule, not an upper stage. That combination would either be very suborbital and land somewhere in the middle of the Atlantic or use an expendable second stage, thus becoming exactly as reusable as F9+Dragon

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17 hours ago, mikegarrison said:

The thing about the Shuttle that most people in this forum seem to constantly forget is that it was its own space station. If it had been designed just as a ferry for people and a limited amount of cargo to a permanent space station, it would have been a lot smaller and cheaper.

It also was built with 1970s technology.

It seems silly to say in the 2020s that the Shuttle taught us that spaceplanes are not a good option. That's kind of like saying in 1950 that the Wright Flyer taught us that airplanes should be made of wood.

It also was hugely instrumental in assembling the ISS. It's not clear the ISS as it exists today could have been built without the Shuttle.

X-37-style spaceplanes appear to be completely viable alternatives to capsules, as far as I can tell. They have some advantages and disadvantages in terms of safety and reliability. I particularly see them as likely more safe and reliable than propulsive landing.

The original STS program was supposed to include the shuttle, a space station, and two tugs (chemical and nuclear).  The advantages of a chemical tug escape me.  I am not aware of the space station being canceled in time to allow the size of the shuttle to drastically change size.  In any event, the Shuttle had to be large enough to fit the latest keyhole satellite (i.e. the envelope of Hubble) in the cargo bay.  Also it needed the massive wingspan to meet the crossrange requirement.  This appears to be the reason it had to be large enough to act as a "space station" even if it was supposed to go to a much larger one.

The real question is how much mass the wings add and how such mass increase scales vs. parachutes.  Propulsive landing appears superior for large uncrewed boosters, but it isn't clear how effective it is for human cargo (except as a means to lessen an already survivable shock).

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3 hours ago, wumpus said:

The advantages of a chemical tug escape me.

The conventional tug was supposed to partially fulfill the satellite repair role and act as a reusable booster stage for probes and satellites.

The nuclear shuttle was for heavy cargo and crewed Mars missions only. People were to be kept off of it as much as possible because of the huge dose of radiation they would get each time it fired. Also, it could be only flown 10 times before the engine became dangerous to fire, so the conventional tug was necessary for lunar flights too.

With DARPA looking at NTRs, SpaceX’s fuel depots, and Dream Chaser, it’s interesting that the architecture outlined by the IPP will ultimately come to fruition (albeit with rough resemblance) under the commercial space industry their government partnerships.

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16 minutes ago, SunlitZelkova said:

With DARPA looking at NTRs, SpaceX’s fuel depots, and Dream Chaser, it’s interesting that the architecture outlined by the IPP will ultimately come to fruition (albeit with rough resemblance) under the commercial space industry their government partnerships.

Agreed, though I'm still doubtful on whether nuclear engines will (finally) reach space or it will do a NERVA/NERVA 2/ROVER/Timberwind/a-ton-other-cancelled-concepts and remain grounded. Who knows, maybe in a decade or two we may see an SPS fleet start being developed

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I think it was Feynman who said (paraphrasing) that the Space Shuttle was an insult to Tsiolkovsky because the heavy part went to space. I'm in the minimal-downmass camp. Most of what you launch to space should stay in space. Someone will come by to reuse the material eventually.

I've had this on my office wall for a decade:

Mars_to_Stay_Traitors_Return_to_Earth.pn

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The Co-founder of the Jet Propulsion Laboratory and father of CNSA, Qian Xuesen said the space shuttle as big as NASA and Roscomos's it's not economically or practically viable. Before Shenzhou came out, there was also a debate on 'Spaceship or Shuttle?' within the scientists in CNSA. However, Qian in the documentary also said that, although the large one is not suitable and not necessarily feasible, a small one isn't impossible. So when the CNSA's technology and everything else was ready, we got the Tengyun:ph34r:

But personally, apart from the technical aspects about the FOBS it really can do. I think the shuttle in size of X-37B and Tengyun is a perfect 'space ferry' from the ground to the orbit. If the TBCC and TSTO adequate technical reserves, it would be possible to see the space shuttle becoming a ferry between Earth and space, as we originally envisaged them to be.

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On 10/21/2022 at 8:25 PM, FleshJeb said:

I think it was Feynman who said (paraphrasing) that the Space Shuttle was an insult to Tsiolkovsky because the heavy part went to space. I'm in the minimal-downmass camp. Most of what you launch to space should stay in space. Someone will come by to reuse the material eventually.

I've had this on my office wall for a decade:

Those boosters weren't light.  And sending more mass for little reason just means you have to send even more mass.  I'd strongly suggest mining asteroids or even recycling existing space junk than adding more to it (although it you *could* recycle space junk then it would make sense to eat the tiny delta-v needed to carry the Shuttle fuel tank into orbit).

I'm on the polar opposite camp.  Not only did the Falcon 9 show the way to go: put 90% of your engines on the booster, only send it up a short ways (so the re-entry damage will be minimal) and recover it.  I'd even recommend using a third stage (like the Falcon heavy, only easier to design) that would return to launch site and preferably be air-augmented.  Granted, that assumes recovering a somewhat smaller booster from somewhat over 5,000m/s (lots of re-entry issues, but only 25% of orbital re-entry) makes sense.  Adding delta-v to mass for no reason takes exponentially more fuel and more rocket.  Don't make any bit of mass go any further than it has to.

Once you can recover boosters, a lot of the old assumptions (three stages only make sense for escaping Earth orbit) need to be questioned.

Since playing KSP and the falcon landings I've wondered if the DC-3 design (two "spaceplanes", fully reusable) would have made a lot better shuttle.  But it couldn't launch Hubble (maybe another telescope half the mass) and it would have to send the ISS up in much smaller pieces (DC-3 could only deliver 1/4 the mass of the final shuttle design).  More pieces - more problems.  And of course there is that pesky crossrange requirement.

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On 10/22/2022 at 3:25 AM, FleshJeb said:

I think it was Feynman who said (paraphrasing) that the Space Shuttle was an insult to Tsiolkovsky because the heavy part went to space. I'm in the minimal-downmass camp.

The fans of Tsiolkovskiy should indeed read Tsiolkovskiy at least once.

He was considering as good the space rocketplanes, and his multi-stage rocket project was a multi-locomotive rocket train pulling the cargo carriage and separating aside one by one.

P.S.
The people are ready to enthusiastically propose any absurd or weird rocket design (including the permanently exploding melted supercritical uranium salt in the engine throat), just to avoid accepting the obvious.

Spoiler

Orion.

 

Like if the liquid nuclear blasts inside are in any part better than the trivial nukes exploding behind.

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13 hours ago, wumpus said:

Since playing KSP and the falcon landings I've wondered if the DC-3 design (two "spaceplanes", fully reusable) would have made a lot better shuttle.  But it couldn't launch Hubble (maybe another telescope half the mass) and it would have to send the ISS up in much smaller pieces (DC-3 could only deliver 1/4 the mass of the final shuttle design).  More pieces - more problems.  And of course there is that pesky crossrange requirement.

It’s apples to oranges. The DC-3 was designed for a very different mission set than the Space Shuttle we got.

The DC-3 existed at a time when the Space Shuttle was not expected to take part in space station assembly because the Saturn V would launch S-II sized monolithic modules, it wouldn’t launch space telescopes (these might have been built in to the station or perhaps launched on the Saturn V itself- imagine a telescope with the S-IC diameter!), and it didn’t need to have cross range capability because it was envisioned as a wholly civilian vehicle with no military participation (beyond the usual connection between NASA and USAF/USSF).

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