Design exercise: Open source personal spaceplane

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Inverted Vantage

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Hi HA. So when I first joined, I was intending to build a rocketplane. My plan was to use this as a testing platform for A) a rocket racer entry, and B)a homebuilt spaceplane. Obviously I was dreaming big...I still don't think it's impossible, though for me if it is ever possible it will be another 20 years before I'm in a position to do anything about the actual construction.

That being said, I think it'd be interesting/useful to talk about designing such a craft; setting requirements, discussing hurdles, etc. I think that a truly personal spacecraft, more so something that can be built at home, is not something that is commonly thought about or even necessarily thought of as "possible".

However, I imagine a two person spacecraft with a 50 mile target ceiling, 2 minute loiter time at apogee, with the ability to be constructed in an average homebuilder's garage.

Major hurdles that I can think of include pressurization, optimization, and the powerplant.

I had some ideas, such as using a pulse jet for the powerplant (300 lbs thrust vs 100 lbs weight, incredible simplicity for the homebuilder), though that presents a host of other problems (noise, fuel consumption, etc).

What do you folks think? How would something like this be tested? Is there anyone else who's thought along these lines? Does anyone have any concepts they'd like to share?

I'm at an event right now so I can't put too much detail into this post, but I will post later. Looking forward to anyone's thoughts. :) Cheers.
 

rdj

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The first nut to crack is the first hurdle you listed--surviving at the low pressures and temperatures of space, and then returning successfully without breaking up or burning up. Note, for example, Burt Rutan's 'feathering' mode for Spaceship One's re-entry. The biggest nut to crack, obviously, is propulsion. Rocket fuel is tricky stuff, and you need to carry/burn lots of it to climb the gravity well. I've occasionally pondered the concept of skipping the 'rocket' part of a rocketplane, at least initially, and using weather balloon 'propulsion' for testing the ascent and re-entry survivability of a rocketplane. For example, this link: Most Impressive Amateur Space Footage Ever!!!!!!!!! - YouTube shows how a 7-year-old and his father sent a camera to the edge of space. Note the winds, the turbulence, and the initial high descent speeds. If you designed and built a homebuilt spaceplane that could survive the ascent to 30,000 meters or so under weather balloons, and then release and return to a successful landing consistently, you'd find yourself a long way down the path of development to a successful rocketplane. And I suspect the overall up-front cost (and hazard) of development would be far less than that for a solid or liquid-fuel rocket propulsion program.

Once you've got a successful spaceplane, attach a fuel/rocket engine module to it, and hook up a few more weather balloons. Lift yourself back to the edge of space, light the engines, and head for orbit :)

Of course, all of this is off the top of my usually-empty head, and I've run zero numbers, so it's probably totally unworkable. However, where there's a will, there's a way:
EAA News - Cluster House Goes Up
 

karoliina.t.salminen

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Hi,

I am very interested on this kind of concept; however, there is this main problem:
it requires some serious up-front investment, someone like Paul Allen with deep pockets to appear from nowhere.
Why? Because it is not only about the rocket plane, rocket engine problems and re-entry problem,
but it quite much requires also the mother ship like WhiteKnightTwo as well.
Why again? Because if you would launch SpaceShipTwo from the ground on rocket power, it would be far shy from the
space on its apogee. I haven't calculated the apogee of SpaceShipOne if launched with rocket power from the ground, but I would doubt that it would go very high this way. This WhiteKnight equivalent needs to be rather large in order to be able to carry the rocket plane to high altitude.
And it does not fit into garage and it is not particularly cheap.

Here is a crazy idea (which might not work, but just a thought):
Double delta two part space plane.
Forward wing, the canard, is a independent delta wing, and is the main wing of the rocket plane. The combination is designed such way that when these two are connected, the rocket plane functions as a canard for the mothership. Then when separated, the CG of each individual plane moves, and both become delta wing aircraft and can land individually as such.
The CGs might not play together as well as I initially thought if some analysis is performed on this, but this came up in the mind from the fact that WhiteKnightTwo and SpaceShipTwo do not take advantage of the lift of the wing of the space plane, and therefore the mothership needs to have larger wing, have more structure, and be larger.

For re-entry, something like Burt Rutan's feather is quite necessary, otherwise you need automated flight control system where a single point failure will be catastrophic. I have Burt Rutan's talk on video where he talks about the evolution of the SpaceShipOne concept from a capsule to space plane, and for the safe re-entry and why he considers that to be of highest importance. I will post it later when I get it edited.
 

Monty

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Mass fraction is the biggest nut to crack. Get it down closer to .5 and you might have something.

Impressive as it may be, I really don't see the point in sub orbital. It's a long way between sub-orbital and orbital energies.

Once you are orbital, re-entry is the problem.

For an orbital ship, the amount of time spent in dense enough atmosphere to use a wing is very small relative to the entire mission, and the wing is just a lot of useless weight to carry around in space. Plus the wing presents a lot of problems on re-entry.

We are up against the limits of the rocket. Space transport using rockets is never going to be cheap. We need a new propulsion method to make it work. If you find something workable, let me know. ;)
 

autoreply

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We are up against the limits of the rocket. Space transport using rockets is never going to be cheap. We need a new propulsion method to make it work. If you find something workable, let me know. ;)
For a typical rocket launch, fuel cost would be what, about 1% of the launch cost? Wouldn't a more economic production and so on yields much cheaper launches?
 

Monty

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For a typical rocket launch, fuel cost would be what, about 1% of the launch cost? Wouldn't a more economic production and so on yields much cheaper launches?
Yes, to a certain extent. But the nature of the mass fraction means that most of your rocket is fuel, with very little left over for structure, let alone payload. That means that the structure and engines must be very high performance, and very highly stressed. This translates to non-reusable and very expensive to design and build. The fuel cost is not the issue.

I hate the rocket equation.
 

autoreply

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Yes, to a certain extent. But the nature of the mass fraction means that most of your rocket is fuel, with very little left over for structure, let alone payload. That means that the structure and engines must be very high performance, and very highly stressed. This translates to non-reusable and very expensive to design and build. The fuel cost is not the issue.

I hate the rocket equation.
Yeah, join the club...

But do you know a way around it?

(For those who don't know it:)


Unless we find a radically better propulsor without the drawbacks from nuclear or ion propulsion I don't really see a way around it?
 

Monty

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But do you know a way around it?
I wish.

If I did, I wouldn't be wasting my time working on an airplane. People with deep pockets will pay big for a warp drive.

I played with rockets professionally for a while. I bought into the whole manned space exploration scam. It wasn't until I put pencil to paper and started calculating that I realized we were wasting our time with rockets. Nuclear rockets make things better. Fusion works even better-on paper anyway. With nuclear rockets we could at least expand to the inner solar system. Without a way to exceed the speed of light (something LHC has just supposedly demonstrated to be possible) we aren't going anywhere other than our solar system.

I certainly hope the physicists will experience some major breakthroughs. Mass-less propulsion is the only thing that makes space exploration really feasible. Energy source and propulsion must be decoupled. As long as reaction mass is our only way of interfacing with space time we are SOL. That and we need to be able to manipulate gravity. We need 1G or at least some significant fraction of it to keep our bodies from self destructing. Our physiology is as much an impediment as the propulsion issue.

You have no idea how much all this pains me. As a lowly engineer, I've got to wait on the physicists. They seem to have gone astray in the last half of the previous century....but

I'm still waiting eagerly for that breakthrough.......
 

karoliina.t.salminen

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I am thinking the following, what would be needed:
1. Orbital space planes which would have safe re-entry and would carry reasonable load to LEO. This is the first breakthrough that needs to happen. Possibly combined ramjet/scramjet/rocket propulsion. No further breakthroughs necessary to advance current state of the art greatly. Not a super-solution that would make the launches dirt cheap yet though. But quite a bit less expensive per kilo than today. I think there was already a concept for that would have had all of this in Germany back in 1936 by Dr. Sänger, but it was never built. The idea here is to use the rocket as little as possible. To not get around rocket equation with rockets, but avoid using rockets for the whole trip. This is not so much breakthrough, but combining existing technologies and making it work.

2. Deep space transports, which would utilize ion propulsion like VASIMR for good fuel efficiency. These would never land to any planet, but would be flying between the planets and would be assembled on LEO (not launched on top of rockets from Earth). VASIMR has been already tested and if there was a very large power supply (like fusion reactor), the VASIMR could be fed with sufficient amount of power for scaling up from satellite ion drives to very large scifi deep space transports.

3. Lander space crafts for landing from these deep space transports, to e.g. Moon and Mars. Landing to Mars is going to be tricky, especially with the intent of getting back up. The air is very thin and the gravity on the other hand is high enough to be a problem for climbing back.

What is then the point of suborbital? I think it is for fun. It has its place and it will advance commercial space technology. But it is only a mid step to full orbital, it is not making colonizing space so much nearer (other than some technologies can be used also on orbital craft, such as carrier aircraft). If I had the money I could afford one, I would love to have a suborbital space plane. Just for fun. However, if I had a station on orbit, I would prefer to go there unless I just wanted to drive a roller coaster in upper atmosphere.

And if I had the privilege on attending a space craft project which had the breakthrough of getting around rocket equation, in other words, some antigravity ufo technology or something, I would surely forget airplanes. However, I am trying to invent (or apply would be maybe better word) things based on known technologies as I am not really one of those scientists which write the new laws of physics but rather and engineer that applies the sciences on practical applications. If I would be one of those, it would be quite unlikely I was typing here on this forum as my interest might be elsewhere than in aerodynamics.

But then: confidence in nonsense; lending Burt Rutan's words: What if you would invest equal amount of efforts on research on some topic than you have for example for developing a new mobile phone or iPad. I would say that one of the reasons why sciences evolve slowly is that 1) it is easier to get research funded if the topic is not outerworldly but will have a concrete goal that can be achieved in some timeframe/roadmap 2) the amount of researchers studying something is more like a hobby club compared to e.g. Nokia/Google/Apple etc. R&D. Also the amount of money spent, even if it sounds large for some science project, can be quite small actually. For example you may have read how much ITER (fusion reactor experiment) would cost and how prohibitive the cost is etc. How about that it is the same cost than a fission based nuclear power station costs to build. The only difference is that the latter will begin to give immediately money back, and the former is a science experiment. Same thing, but different scale, cancer research. There is a doctor that does research on virus based treatment for curing cancer. Again even if it is better than state of the art, it is relatively a hobby club, one doctor and some assistant maybe. Doing progress because he is good probably, but the mass and momentum is lacking. The findings are not used immediately everywhere (but only after years, sometimes tens of years) despite it could save very many lives. There are thousands of engineers almost next door. Why only engineering projects can scale, why can't research projects scale? I am quite sure, that being Einstein is not a special condition of some super brain, but hard work and dedication of a clever, but otherwise quite ordinary, but enthusiastic individual who does what he or she wants rather than thinking what maximizes the money he or she gets. What if there were thousands of those? I would say that chances would be much better for some progress on also some other area than mobile phones and other gadgets.
 
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autoreply

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Many people, even a number of AE professionals seem to have the idea that the "Rutan-style" bumps are a significant step towards (affordable/commercial) space flight. Like Monty, after reviewing the basics it pretty soon becomes clear that it's not. Going to 60 miles up (or even to 200 miles, where the ISS flies) has barely anything in common with the challenges that face spaceflight. Yes, you might temporarily be in the same place, 200 miles up, but apart from that there's nothing in common between those two approaches.

The energy (both required for acceleration and for safe descent) are roughly a hundred times higher per pound for orbital flight, compared to SS2. SS2 sees a max total temperature of 200 Celsius or so for maybe several dozen seconds and a skin temperature that's bearable by humans. An orbital return would yield temperatures of close to 10,000 Celsius with skin temperatures of a couple thousand degrees, during a few minutes.

There's no way around this, unless you would brake with a rocket but that increases your launch mass by a factor of 20 or so. There's a reason the Saturn V was so massive...
 

Inverted Vantage

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I think my idea of the challenge for this project is less about advancing the overall field of space travel (unless someone wants to build a reactionless engine; there's those concepts that beam microwaves at a disc-shaped spacecraft to propel it upwards), and instead introduce more people to it and give them the opportunity for space travel. Small aircraft that are cheap and can be built at home would give more people a chance to experience spaceflight (as much as 50 miles up is), and encourage more development in that direction. Sort of reviving the idea of real public space travel.

I think focusing on trying to solve the challenges of interplanetary flight or LEO is beyond the scope of a homebuilder, nomatter how skilled. A small craft that goes 50 miles up though, I think that's doable.

On the subject of pressurization; what about not having any? I'd like to see some tests of those skintight pressure suits that people talk about.
 

Aircar

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Check out the space elevator consortium --there is even a prize competition for the best tether and the best climber (the cable that dangles from space and the elevator itself -- crawls up the cable with power supplied by a laser beam or microwave or someother source )
 

Ranester

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One of my favorite subjects.

My solution would be a two stage rocket. First stage would be powered by RP1 and H2O2; this combination has the benefit of the simplicity of using HTP decomposition energy to drive the propellant pumps, without the difficulties associated with pre-burners; the problems with highly oxidizing environment should still be addressed though. It also does away with the problems related to cryo materials. A rocket chamber consuming 25 kg/s of propellant would yield about 65kN of thrust (EDIT: -at sealevel. Once the rocket climbs to higher altitude, the Isp improves and thrust increases to about 72kN.) With two cores, each consisting a cluster engine of four nozzles, the first stage would have total thrust of 520kN (roughly 117 000 lbf) which should be enough for a lightweight second stage vehicle. The construction of this stage would be basically a capsule-shaped carbon fiber tank with an internal section wall. Further weight savings are achieved by using balloon style tanks, ie. the internal pressure keeps the tank from collapsing. After use, the stage descends into ocean by parachutes to be recovered and reused.

The second stage vehicle would be a lifting body air/spacecraft in the spirit of M2F1; the lifting body design would still allow fair cross-range while avoiding using mass budget on mostly useless wings. The craft would be equipped with integral tanks for LO2/LH2, fed to the rocket engine by pistonless pressure pumps. This engine type is almost as simple as pure pressure fed system, while avoiding the problem with heavy tanks and achieving higher chamber pressures. Orbital maneuvering would be done with leftover propellant, ullage and RCS systems would be powered by HTP fed from a bladder tank. Energy would be provided by three independent systems: solar panels, fuel cells fed with gaseous H2/O2 collected during maneuvering, and an HTP turbine for emergency power, drawing from the RCS tank. The passenger capacity could be perhaps four occupants, and the docking collar for ISS. The cockpit/crew area would be a pressurized capsule within unpressurized shell. This isolates the pressurized area from the effects of thermal expansion, and provides slight extra protection against space debris.

The re-entry would use Rutan's trick; the stabilators would feather the spacecraft into belly-first position to maximize the area facing the stream. This maximizes the aerobraking capability, but also reduces peak temperatures on the surface. The very low mean density brought by the empty propellant tanks help in the heat problem further. The outer layer of the heat shield would be super alloy shingles. These shingles would be spot welded from two pieces, the smooth outer layer and the embossed inner layer. The bosses would serve as anchors for super alloy wire wrapping. The wire itself would be woven to a ceramic cloth between the anchors. An inner layer would be sewn like a quilt onto the outer sheet, with a thin layer of mineral wool in between. Finally the blanket would be bonded to the spacecraft surface by heat resistant insulating rubber.

Landing a M2F1-style aircraft is more tha slightly tricky, so it'd be best to use a parachute for the touchdown. In pilot reports the M2F1 was said to match the flight characteristics of an F-104, flying the engine at idle, landing gear extended and flaps deployed. Which means it flew better than a rock, but not enough to tell the difference.
 
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Inverted Vantage

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Interesting idea Ranester, though I'm seeing several flaws, well, more like complications. Firstly you make use of turbopumps; notoriously fickle, expensive, and difficult to maintain parts. You also have a big chunk of the rocket (the first stage) dropping off; a nightmare for regulations, difficult to find a spot to launch out, harder still to find a trajectory that won't put you over civilized areas. After that, you have a situation where you're trying to get a homebuilder to recover the first stage; a difficult if not impossible task unless they own a boat or are part of a very large network.

The second stage is interesting, I like the idea of having it as a lifting body; a great task for composites. I don't think you will actually need that much for orbital maneuvering, again, it's only supposed to go up about 50 miles; enough for 2 minutes of zero g and a view of the Earth's curvature. Other than for a pure thought exercise, designing an orbital vehicle as a homebuilder is a rather fruitless exercise at the moment.



What I discussed with my friend, and may be getting more feedback on in the future, is the idea where you have an aircraft with one to four jet powered UAVs attached to it. The UAVs power the aircraft up to about 20 miles, detach, and fly back to the home airport. The aircraft then ignites one or several pulsejet engines (so chosen for their lightness, cheapness, durability, and ease of construction), powered by compressed O2 (thus hopefully navigating around the issue of having uncompressed air thus leading to poor fuel efficiency of pulsejets), which powers it up to altitude. The pulsejets would also provide endo-atmospheric capability as well, so if necessary the aircraft could cruise or land under it's own power.

Another major issue that I am observing is manufacturing; these things should be as simple to build as possible. You're not going to get that by including turbopumps, precision nozzles, etc.

Either way though, I really am with karoliina on the necessity of building more interest in this area. One of the main reasons I look at it is because the elephant in the room is that unless there's a major die-off of the species, there are simply too many people on this planet. No amount of "going green" or "being more sustainable" will fix this; if you run the numbers, some people will have to die so that others can live. Die - or leave.
While we're not at that stage yet, I think right now we're at a tenuous time for the foundations of space travel in the future. Budgets and aspirations are being cut all across the globe; space travel, aside from military or telecomm use, is being pushed aside.

It sort of goes with my whole goal for making flying cheaper; the more people do it, the more interest there is, the more knowledge there is being passed around, the more and more rapid development is being done. Right now it's very limited; it's expanding, but it still is limited. By bringing more people into the fold, especially with a small, homebuilt, very light lift thing that basically gives people the ability to say that there is an actual chance they might get into space, is a serious thing for the community and the effort, and I think that is what should be designed for, as open as possible so it stretches as far and as wide as possible.
 

PaulS

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An "economical" space plane means getting the velocity as high as possible while inside the atmosphere to lessen the need for oxidizer.
This could be accomplished with a scram jet up to about mach 12 or so.
Orbit will require about 50% more speed so you will need a rocket engine to get to orbit and to control the craft at high altitude where the air thins out.
This could make use of the scram jet by closing the front off and injecting small amounts of high explosive through the nozzle for thrust. It would require less fuel and oxydizer than conventional engines and develop more thrust than ion or similar devices.
Re-entry from orbit requires heat shielding. There is simply no way to slow the craft from 17000 mph quickly enough to avoid a ballistic re-entry so I suggest a fully cast ceramic vehicle with the reinforcing framework, engine and mechanicals cast in place where possible.

Just the ramblings of an old madman who did not bother to think it through.
Paul
 

autoreply

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Either way though, I really am with karoliina on the necessity of building more interest in this area. One of the main reasons I look at it is because the elephant in the room is that unless there's a major die-off of the species, there are simply too many people on this planet. No amount of "going green" or "being more sustainable" will fix this; if you run the numbers, some people will have to die so that others can live. Die - or leave.
So they though before:
Malthusian catastrophe - Wikipedia, the free encyclopedia
While we're not at that stage yet, I think right now we're at a tenuous time for the foundations of space travel in the future. Budgets and aspirations are being cut all across the globe; space travel, aside from military or telecomm use, is being pushed aside.
Might be true. But even in the most wild and optimistic scenarios we're talking of dozens of millions of investment money. That might be an interesting opportunity for people like Branson, but not for a single individual.

Pulsejets vibrate extremely. Running in the atmosphere they're reasonably efficient, once out of it, there's really no point in using them.



But talk about things like scramjets, controlled (atmospheric) flight at hypersonic speeds and so on, really?

We're talking about a craft with TWICE the fuel fraction of Rutan's Voyager, a surface temperature of thousands of degrees Celcius and so on. Ow yeah, and you first have to accelerate it to Mach 5 or so, to get it to start. And after you've then lit your Scramjet and accelerated to Mach 15, you're still only halfway on your speed budget...

Just focus on the rocket formula:
945a66bb8ac5a46fd959ab6c12eebb00.png

and think about the consequences. In plain English, to get 1 pound of mass in orbit you need the energy of 5 to 10 pounds of fuel, which you also have to carry up then.

Turbobopumps are the real problem. A classic rocket needs to raise the pressure to 100-200 bar. That's 200 ton per square feet...

That's where the real challenge lies, a cheap, simple and reliable rocket engine.
 

Hot Wings

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Check out the space elevator consortium --there is even a prize competition for the best tether and the best climber (the cable that dangles from space and the elevator itself -- crawls up the cable with power supplied by a laser beam or microwave or someother source )
Blasphemy! That doesn't involve flying of any sort unless you get stuck at less than G zero and have to bail out. Please stay on topic. :gig:
 
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Hi HA. So when I first joined, I was intending to build a rocketplane. My plan was to use this as a testing platform for A) a rocket racer entry, and B)a homebuilt spaceplane. Obviously I was dreaming big...I still don't think it's impossible, though for me if it is ever possible it will be another 20 years before I'm in a position to do anything about the actual construction.

That being said, I think it'd be interesting/useful to talk about designing such a craft; setting requirements, discussing hurdles, etc. I think that a truly personal spacecraft, more so something that can be built at home, is not something that is commonly thought about or even necessarily thought of as "possible".

However, I imagine a two person spacecraft with a 50 mile target ceiling, 2 minute loiter time at apogee, with the ability to be constructed in an average homebuilder's garage.

Major hurdles that I can think of include pressurization, optimization, and the powerplant.

I had some ideas, such as using a pulse jet for the powerplant (300 lbs thrust vs 100 lbs weight, incredible simplicity for the homebuilder), though that presents a host of other problems (noise, fuel consumption, etc).

What do you folks think? How would something like this be tested? Is there anyone else who's thought along these lines? Does anyone have any concepts they'd like to share?

I'm at an event right now so I can't put too much detail into this post, but I will post later. Looking forward to anyone's thoughts. :) Cheers.
Single seater rocketplane airlaunched from a mother plane. Pressure fed rocket system of about 4,000 lbs thrust. 900 to 1,000 lbs empty weight. 3,000 lbs loaded weight. Deploys a ballute during re-entry to stabilize it until it descends into thicker air.
 
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An "economical" space plane means getting the velocity as high as possible while inside the atmosphere to lessen the need for oxidizer.
This could be accomplished with a scram jet up to about mach 12 or so.
Orbit will require about 50% more speed so you will need a rocket engine to get to orbit and to control the craft at high altitude where the air thins out.
This could make use of the scram jet by closing the front off and injecting small amounts of high explosive through the nozzle for thrust. It would require less fuel and oxydizer than conventional engines and develop more thrust than ion or similar devices.
Re-entry from orbit requires heat shielding. There is simply no way to slow the craft from 17000 mph quickly enough to avoid a ballistic re-entry so I suggest a fully cast ceramic vehicle with the reinforcing framework, engine and mechanicals cast in place where possible.

Just the ramblings of an old madman who did not bother to think it through.
Paul
Spaceplane does not automatically mean orbital. The X-15 and SpaceShipOne were suborbital.
 
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