Design a One Stage Launch Craft?

[Technical Ben]

What ideas do you have for a one stage space craft for launch into orbit? Lets say to the International Space Station.

I've been toying with the idea of designing a fictional one stage launch craft. Mainly because of all the Sci-Fi films I've seen recently, and the posts on space flight on this forum.
To make it more fun, I was wondering if anyone here would want to add ideas to the design. Then we can have a kind of "XKCD forum Launch Craft". I can then use Google Sketchup to make the design.

I've modelled up the current NASA x-37b in the size of something that could carry a few passengers. But that is a 3/4 stage craft at the moment. Looks like this.

(Size comparison to Saturn V Rocket. I did not model the Saturn V. Cover to the shuttle not shown either)

I would want to limit this to current technology. At least for the first design. So keep it to things that have been tested or are currently in use. For example, no Orion drive, as none have been tested. But anything like Sabre or inflatable heat shields are acceptable.

For more details, I'd like to calculate things like fuel tank sizes etc. But that's not the most important part. How cool it looks is.

[Kang]

Okay, here is a suggestion: look at the size-comparison Saturn V you got there. That is a two-stage rocket that sent its payload all the way to the moon. It isn't exactly a puny little firecracker. I don't think you really need to double the size of that, especially since a massive single-stage launcher wouldn't be nearly as practical for reaching further destinations.

[Antimony-120]

Okay, here is a suggestion: look at the size-comparison Saturn V you got there. That is a two-stage rocket that sent its payload all the way to the moon. It isn't exactly a puny little firecracker. I don't think you really need to double the size of that, especially since a massive single-stage launcher wouldn't be nearly as practical for reaching further destinations.

Note that the Saturn-V only sent a few people to the moon, hence the difference in payload size. Also note that that is a multi-stage craft that is modelled.

The reason for the one-stage constraint is that in most sci-fi the spaceships do not need a second stage. In terms of plot this is useful as it means that fuel is the only needed resource, as opposed to fuel and a well (and often custom) designed, precision made part that will only be used once.

It's not a particularly practical setup from a thurst-to-fuel-ratio perspective, but if we handwave that away and suggest fuel is cheap and parts are expensive, it becomes more interesting. I believe the op simply wanted to investigate a practical single stage craft under present technology to see what sort of limitations and options that setup brings with it.

Unfortunatly I don't have the time to investigate, and I'm not familiar enough with the engineering to suggest anything without investigation. But I'll watch this thread closely.

[Kang]

Note that the Saturn-V only sent a few people to the moon, hence the difference in payload size. Also note that that is a multi-stage craft that is modelled.

Indeed, there is a difference in payload. I was more or less assuming this was supposed to shoot for LEO for obviously silly reasons.

The reason for the one-stage constraint is that in most sci-fi the spaceships do not need a second stage. In terms of plot this is useful as it means that fuel is the only needed resource, as opposed to fuel and a well (and often custom) designed, precision made part that will only be used once.

It's not a particularly practical setup from a thurst-to-fuel-ratio perspective, but if we handwave that away and suggest fuel is cheap and parts are expensive, it becomes more interesting. I believe the op simply wanted to investigate a practical single stage craft under present technology to see what sort of limitations and options that setup brings with it.

Unfortunatly I don't have the time to investigate, and I'm not familiar enough with the engineering to suggest anything without investigation. But I'll watch this thread closely.

Yes, but the concept of the launcher with a craft on top implies the launcher is expendable, as otherwise it would have to be re-docked to and then survive reentry just like the craft, making a self-propelled spacecraft overall a better simpler option, provided that in this scenario it would be possible of course. Alternatively a shuttle to be launched by cannon or electro-magnetic rail (or getting launch assistance by either) would be an idea worth thinking about.

[Technical Ben]

I'll go with the "fuel is cheap" option.
I will post up some designs for a one stage later today. Something similar to the Nasa designs.

It does not need to be too accurate. I was just looking for input and ideas. Thanks for the comments!

[Technical Ben]

So, here is something similar to the NASA X-33.


With normal jets to get it into flight, a lifting body, and big boosters on the back.

[Kang]

Looks nice. Just one thing: if you put a payload bay in the back you lack the room for the center boosters. Also you might want to add an intermediate mode of propulsion like a scramjet engine.

[Technical Ben]

Thanks. The jets would have to be some sort of scramjet yes. Or hybrid. The fuel would be in the sides of the bay, as it's got a wide body.

[Kang]

About the bay I meant that on the picture it looked like the central boosters would extend straight through the payload bay, rendering the latter useless, but that can easily be cured by either removing the two center engines or maybe moving the payload bay further to the front, maybe rotating it by 90° in order to make use of the width. You could fit a scramjet on the bottom side along the whole fuselage and keep traditional engines in the top nacelles, as a scramjet doesn't work until you reach a fairly high speed.

[Technical Ben]

Added a scram-jet. Some idea of the layout available. Plenty of room to fit the payload and the rocket engines.

[scarecrovv]

My advice is to get as high and fast as possible for free by utilizing ground facilities. Possibly a rail-gun on a mountain. Possibly a big laser array for a lightcraft. Anything to reduce the amount of fuel you need to spend getting above the atmosphere, and up to speed.

[Technical Ben]

I could use a rail launch. But I don't want to squash the occupants though. Having it "unaided" would be preferable. Else I'd probably go with sticking it on a big Jumbo Jet. Saves on the extra engines too.
PS, the Sabre engine does not need to bring it's own oxygen. A scram jet would also be very efficient.

[ikrase]

My suggestion: Don't try single stage. Use NERVA powered winged shuttle airlauncehd form supersonic transport.

[Technical Ben]

My suggestion: Don't try single stage. Use NERVA powered winged shuttle airlauncehd form supersonic transport.

I'll look into NERVA for propulsion. But for the craft to fit even remotely into any Sci-Fi world, we would need a single sage.
Besides. I like challenges!
[edit]

Updated a nuclear rocket version. Ok, it's also a design borrowed from NASA. I'm not a rocket scientist.



If the rocket burns all the material cleanly, it's not really a radiation risk. So quite a lot more viable than a full Orion drive.

[ikrase]

Part of the reason for my idea is that you need tons of extra shielding to use high power reactors in the lower atmosphere. With my idea, it is only used very briefly for landing - or not at all if you have the turbojets.

Incidentally, the shuttles in 2001 A Space Odyssey were two-stage.

I think you should sling the jets either completely over or under the wings and round the bottom surface more. No sharp edges on reentry vehicles...

Also, the fuel tank probably needs to be bigger. LH2 is a very low density compound. I think that there are actually more hydrogen atoms in a gallon of water than in a gallon of liquid H2. To reach orbit from the ground, using NERVA type engines at maximum efficiency (VTOL will be hard here) you need (by weight) about 2 parts fuel and 1 part structure, engine, payload, etc.

[Technical Ben]

Thanks. I will bear that one in mind. I'll keep a 2:1 ratio for fuel/shuttle. I'd aim for a 8:1 ratio, but don't think it's possible. For example, if it's launching from the moon, we need our own O2.

[bigglesworth]

Why not have a two- or three-stage craft but with re-usable stages?

[Technical Ben]

For earth that is fine. I'd love a planet hopper/shuttle though. Something that can be launched from a mother ship, land on a planet, then return. The long term goal is something that can work on just about any planet. So, Earth, Mars, the Moon and any others found out there. But without an atmosphere, some planets would be a lot more difficult to launch from than others.

I'll give a 2 stage a go this time. A micro shuttle strapped to a launch craft.

[bigglesworth]

Hmm, how about a two or three stage, and each of the stages can be launched on top of other stages.

So the payload + humans are in stage 1, there is also stage 2 and 3, but a stage 2 can be launched on another stage 2+3 or a stage 3 could be launched on a stage 2+3.

So to get together something that could land on another earth-gravity planet, you'd have three launches: 1+2+3, 2+2+3 and 3+2+3. And then you'd have one launch on the return.

[Technical Ben]

Not oh so reusable though. But good idea. interchangeable parts is very handy.

[bigglesworth]

Well, each of the stages could be made reusable, at extra cost.

[Kang]

But the craft as a whole would need to be reassembled for every launch, which for scifi environments is usually not very handy for dramatic reasons.

[bigglesworth]

It could be reassembled in a simple montage! Or even just cut to it being assembled. It works for dialling the Stargate.

[Technical Ben]

But the craft as a whole would need to be reassembled for every launch, which for scifi environments is usually not very handy for dramatic reasons.

Well, this is where I do reach a conflict of interest. The craft only has to be realistic. It does not need to be interesting. However, I'm a firm believer you can make real things look awesome.
Check out any real rocket launch for an example.
The strangest launch was one of the latest heavy lifters. It just looked so fake though. It floated smoothly off the ground, and up into the air. I guess that's what you get when they get really good at it.

[edit]
So here are 2 designs. One keeps to my single stage idea. A craft that can drop onto a planet, then launch back up (or visa versa). A bit smaller than a Saturn V. Can have extra stages added for fuel. Has to use a lift/cradle to get to the ground though.



Then a launch from a plane. Inspired by Virgins launch craft. Not put much time into this one, so it looks rather silly...

[Kang]

It could be reassembled in a simple montage! Or even just cut to it being assembled. It works for dialling the Stargate.

The dramatic problem I see there is rather along the lines of:
«We need to escape that angry alien mob now! Prepare for launch immediately!» - «Alright... check back with me next tuesday.»

[scarecrovv]

It could be reassembled in a simple montage! Or even just cut to it being assembled. It works for dialling the Stargate.

The dramatic problem I see there is rather along the lines of:
«We need to escape that angry alien mob now! Prepare for launch immediately!» - «Alright... check back with me next tuesday.»

So make it a dramatic moment by flipping it backwards: "We need to escape that angry alien mob now! Prepare for launch immediately!" - "What have you done!? I told you guys to give me until next Tuesday before pissing off the locals!" - "Well that's great, that's just fuckin' great, man. Now what the fuck are we supposed to do? We're in some real pretty shit now man..." - "We'd better get back, 'cause they mostly come at night... mostly."

[Kang]

I hadn't seen it from that point of view. Rack it up on my list of 'things I didn't think through properly'.

[Technical Ben]

"If you don't hurry up, I'll kick you out so you can walk home!"

[Spen]

These can probably both be shot down in burning flames by you guys but here goes:
Launch the craft from a rail-gun type arrangement with some type of light craft mounted on the rear, then when it reaches the top of the parabola create a turning moment causing the craft to tip until the angle of flight is 45 degrees (probably not the optimal angle due to air resistance) from the horizontal with the lightcraft set-up being triggered at this point almost making it a secondary launch.
Problems:
Air resistance of light craft arrangement
Power of laser for the light craft will be dissipated in the atmosphere

Use a space plane which is launched from a runway and is accelerated up to escape velocity by moving around the earth within the atmosphere while being accelerated like a particle is in a cyclotron, the inward seeking force would be caused by a magnetic field with a very high flux density being opposed to the planets magnetic field at that point.
Problems:
If your planet doesn't have a magnetic field you're in trouble.
Huge power requirements, you need to ensure that there is a band around the earth which is completely clear for the period of the launch effectively cutting one half of the globe off from the other by means of air travel for the duration.
What CAD software are you guys using for this?

[Technical Ben]

I have Sketchup. I also have an old copy of some 3d graphics software, but sketchup is quicker.
Thanks for those ideas. If I have time I'll try a rail launched idea. However, most Sci-Fi has personal shuttles launched from a mother ship. These land on the planet, then return to the mother ship. I know I can cheat with "warp drive" or "transporters". But for anything near future, or non-"magic", it would need to be more realistic.
Seems it is more difficult than I originally thought. ATM it's a full scale Saturn V style launch craft for anything not using Unobtaium or antimatter.

[edit]
Just found this site...
http://www.amcsorley.dsl.pipex.com/index.htm
Wonder if I/we could use it to "test drive" the ideas!?!

[Kang]

I like Orbiter and considered mentioning it, but I've never quite looked into implementing new vessels. In theory it shouldn't be too hard.

[HopDavid]

What ideas do you have for a one stage space craft for launch into orbit? Lets say to the International Space Station.

Are you talking about a SSTO RLV? (Single Stage to Orbit Reusable Launch Vehicle). This has been the holy grail of aerospace engineering for a few decades now.

One of the problems is an ~18 delta V budget for earth's surface to LEO and back.

Initial mass/final mass in LEO = e^(delta V/V exhaust)

To get off earth's surface you need a decent thrust to weight ratio. Otherwise you suffer terrible gravity loss during the vertical ascent. And the initial part of trip needs to be a vertical ascent, especially if you're departing from a world with an atmosphere.



Unfortunately good ISP usually means poor thrust. So generally lower ISP but better thrust kerosene is used in the lower stage. Better ISP Liquid oxygen and hydrogen are often used for upper stages where you don't have to battle gravity loss.

If you're using a single stage with one sort of propellant and rocket engine, the low ISP as well as the high delta V budget mandates an extremely challenging mass fraction.

Re-entry is another challenge. The last 8 km/sec of the Shuttle's delta V budget was accomplished with aerobraking. Shedding 8 km/sec over an hour's time subjects the craft to lots of abuse. In a Nasa Space Flight thread Danny Dot mentions that Shuttle leading edge is 3000 degrees F. A mach 25 re-entry presents challenges.

[ikrase]

My suggestion is to one. Use Nuclear power. 2. Use ramjets, scramjets, or a variation. 3. Do not obsess over single stagedness.

The solution I like the best consists of three parts:
1. Supersonic/Suborbital Transport. This vehicle is not solely for rocket launch, it is also a cargo vehicle. (Entering Space suggests market exists for four-hour intercontinental mail, and other markets). Used to piggy back launch from high speed and high altitude. If (sc)ramjets are practical , they should be used. This will provide about 1km/s dV at minimum (much more if ramjets or scramjets are used), plus whatever is wasted in getting off the ground. It can take off at an airport, and then go on to make its delivery and land on the other side of the world.

2: Universal Nuclear Space Shuttle: Powered by a DUMBO or NERVA variant rocket. Is lifting body re-entry vehicle, has dV of 7000-8000. This will be smaller than the STS orbiter. Therefore, it can launch into LEO from the back of the Supersonic/Suborbital Transport, be able to maneuver (which the Space Shuttle can barely do), and then land vertically. This would have no cargo bay, but it would have a flexible pressurized compartment able to take either several people (for space station service, etc) or a bunch of in-pressure cargo (replace the Progress, plus be able to recover equipment.) If delivered into orbit around another planet, it can have fuel for one landing and one takeoff. (Mars, Moon, or Titan under consideration).

3. Universal Nuclear Cargo Launcher: For launching large objects, but not for landing them. This consists of a very compact NERVA/DUMBO core, rocket engine, frame, ballistic heat sheild, and fuel tank with a fairing to go over the much larger payload. This is for launching sattelites. It is popped into suborbit, lifts into orbit, and then jettisons the payload, deorbits, reenters, and lands w/parachutes and/or airbags.

[Technical Ben]

Thanks HopDavid. I've come up with something that looks like it's out of Space 1999. So it's no longer a single stage, but can have the stages needed swapped on/off at launch.
For anything bigger than a shuttle, I will have to go with "antimatter power" hand waving to have the power density. Only because I don't want a massive fuel tank on the side. Perhaps in som other artwork/designs I do, the giant fuel tank would look cool.

Ikrase, would something similar to the Luna lander be of any good? A capsule launches from your "mothership" which then drops the Luna lander. The Luna lander, then jettisons back up to the casual, and returns to the mothership. If the planet has an atmosphere, you could use a different type of shuttle (your type 2).

I understand you need even more fuel if your landing on an atmosphere free planet. I wonder if this would become a limiting factor.

[HopDavid]

2: Universal Nuclear Space Shuttle: Powered by a DUMBO or NERVA variant rocket. Is lifting body re-entry vehicle, has dV of 7000-8000. This will be smaller than the STS orbiter. Therefore, it can launch into LEO from the back of the Supersonic/Suborbital Transport, be able to maneuver (which the Space Shuttle can barely do), and then land vertically. This would have no cargo bay, but it would have a flexible pressurized compartment able to take either several people (for space station service, etc) or a bunch of in-pressure cargo (replace the Progress, plus be able to recover equipment.) If delivered into orbit around another planet, it can have fuel for one landing and one takeoff. (Mars, Moon, or Titan under consideration).

As I mentioned earlier, ascending to orbit from a planetary surface takes a good thrust to weight ratio. Else you suffer show stopper gravity loss.

And NTR doesn't have good thrust to weight ratio. See SSTO is a bad idea, but NTR SSTO is worse.

Further, it seems to me a Nuclear Thermal Rocket engine would suffer a lot of abuse during it's use. I'm not sure how reliable it would be. Good old hydrogen/oxygen RL-10s are a better bet for reusable rocket engines.

[Technical Ben]

Did I read that right though? We only need a NTR one third the weight of current designs to succeed? I could envision that for a future tech. Probably not "current tech" though.
HopDavid, do you know any sites/macros where I can punch in some really laymen and simple figures to get out the performance of a rocket design? Things like thrust, delta V and weight, fuel etc. The maths goes way over my head.

[zmatt]

the biggest problem on thrust to weight ratios for NTRs is the reactor itself. NERVA weighed ALOT. If you want nuclear rockets to be able to get off the ground or to be anything near practical you would need to figure out how t make compact reactors. And by compact I mean the whole shebang weighing as much as a conventional liquid fuel setup. Cold fusion is completely bs, so get back to me when you have done this. if you want to look into the future you could theoretically achieve the same thing with an antimatter reaction which eliminates the weigh concern considering how little you need, however nobody has even started on the engineering problems associated with using antimatter as fuel. Right now it's a nice idea.

The problem with mass drivers is if the thing is manned you just killed your crew as a mass driver will accelerate you to top speed at the muzzle. That is very bad. It is quite literally like getting shot out of a gun. I don't want to think of the G's that would put on you. This isn't a problem for unmanned craft of course.

I like the scramjet, air launched , lifting body thing we have going on here. I would hardly call it ideal, but it is something doable today and would achieve more than anything has up to this point.

[ikrase]

The nuclear upper stage never takes off vertically from Earth with full fuel. It has a mass ratio of about e. (2.8.....) and t/w 8 or higher is supposed to be possible with NTR's, let alone LOX enhanced NTR's. It is lifting and is piggyback launched at high speed and altitude.


Step ONe: Stack Takeoff.

Step 2: Stack acclerates to 1500 m/s, 20-40 km alt.

Step 3: Seperation of shuttle. Shuttle accelerates to orbital velocity.

[idobox]

My suggestion would be a space plane with nuclear powered scramjets to get as fast as possible while still in the denser part of the atmosphere, going through a parrabollic trajectory, and using Orion style bombs at high altitude.
In a Sci-Fi setting, we could imagine "clean" fusion bombs / inertial confinement fusion power. As much as I understand, a bomb, chemical or nuclear, has the best thrust/mass ratio and muzzle velocity.

Alternatively, for an exploration shuttle, we could imagine beaming power from the mothership. That would be insanely cool.

[bigglesworth]

I think for PR purposes, we'd have to rename the 'bombs'.