Gundam Spacecraft

[Arbiter GUNDAM]

I've been wondering about the dome-shaped HLVs that get used in a lot of Gundam series. I'm not sure, with their payload space, that they'd have enough fuel and oxidizer to make even Low Earth Orbit. Maybe they also use Nuclear Thermal Rockets? Of course you'd have to solve the problem of radioactive exhaust and I don't think NTRs are really that suitable for launch...

[toysdream]

Nuclear thermal rockets aren't necessarily radioactive - they use the heat of the reactor to heat the propellant, just like a nuclear powerplant uses the reactor heat to turn water into steam. Unlike a fusion rocket, the propellant doesn't need to flow through the reactor core.

Nonetheless, the engines on HLVs are probably just chemical rockets. They have big old boosters for getting into orbit, and mobile suits are amazingly light given their size, so this doesn't seem unreasonable.

-- Mark

[Brave Fencer Kirby]

How the Universal Century accomplishes its bulk lifting into orbit is a very good question that's never really been answered to my satisfaction. Presumably HLVs do the lion's share of the work, since to my knowledge we never even see another dedicated surface-to-orbit bulk cargo craft, but it honestly doesn't seem like a very good ship for the job. You'd want such a vessel to be huge, cheap, and efficient -- the semi truck of the skies. Using old-fashioned chemical rockets that require huge boosters just to get into orbit doesn't seem to fit the bill.

[Nebfer]

How the Universal Century accomplishes its bulk lifting into orbit is a very good question that's never really been answered to my satisfaction. Presumably HLVs do the lion's share of the work, since to my knowledge we never even see another dedicated surface-to-orbit bulk cargo craft, but it honestly doesn't seem like a very good ship for the job. You'd want such a vessel to be huge, cheap, and efficient -- the semi truck of the skies. Using old-fashioned chemical rockets that require huge boosters just to get into orbit doesn't seem to fit the bill.

Well we do have artwork on the HLVwith it's boosters, not to mention a Fed Space shuttle and then the Komusai II

All of which have fairly significant boosters, the HLV seems to have the smallest booster ratio, but even that is fairly large compared to the actual craft. The Ginga has a massive booster rocket, much like the space shuttle (which it seems to be based off of), but with a much larger tank, most likely to allow larger lifts (like 50+tons, which is twice that of what the space shuttle can carry) and to go much further out (shuttle is limited to low earth orbit, this is not likely the case here). Though not much info is given on the engines, though IIRC units like the HOTOL use nuclear engines, which would give them decent economy in the fuel departments.

In any case most of what we do see seems to indicate that lift capability's of 100+ tons is very common, and 200 or more is also not unusual.

[MythSearcher]

Nuclear thermal rockets aren't necessarily radioactive - they use the heat of the reactor to heat the propellant, just like a nuclear powerplant uses the reactor heat to turn water into steam. Unlike a fusion rocket, the propellant doesn't need to flow through the reactor core.

Nonetheless, the engines on HLVs are probably just chemical rockets. They have big old boosters for getting into orbit, and mobile suits are amazingly light given their size, so this doesn't seem unreasonable.

-- Mark

Given an ideal case with the Delta-V calculation with the rocket formula, you need around 25 times the payload mass for the propellant, that is why we have really large boosters and relatively small payload volume, since the propellants are not very space efficient. Although most Gundam shows ignore Delta-V in the mechanical designs, surprisingly, quite a lot of large ship launching scenes are quite accurately showing boosters that are big enough. First Gundam's scene of launching Magellans and Salamises that seems to have enough propellant in their addon thrusters, the Gundam CG Works actually did a calculation of Delta-V for those and they hold accurate. The HLV's seems to be possible(with the HLV itself quite spacious inside and a similar height booster) and the Zanzibar class booster almost as long as itself.

Depending on your efficiency requirement, chemical rockets are usually not a good choice.
http://www.projectrho.com/public_html/r ... nelist.php
Look at the vertical lines, which are different types of rockets, and the horizontal lines, which are the different launch requirements.
Earth Liftoff is the 10th horizontal line from the bottom, and Chemical maximum is the 4th from the left.
We can see how inefficient Chemical rockets are.
The problem here would be the absolute thrust of more delta-V efficient rockets are usually not every high, and becomes quite inefficient if used under gravity.
Hence Liquid fuel chemical rockets, although have a higher fuel efficiency, is lower in efficiency for Liftoff than Solid fuel chemical rockets.
Ion drives, which are even more efficient in delta-V than liquid fuel, cannot even manage to liftoff with its thrust to mass ration...
Hence most of the rockets nowadays uses solid fuel for their boosters and first and/or second stage, but liquid fuel or even ion drives once in space.

So you might be right in the HLV using Chemical rockets for their boosters, its just more efficient that way.

[Juumanistra]

There's really only one way to achieve Gundam's stated lift goals on its stated time-table in such a way that does not radically alter everything we associate with spaceflight, and that's Ol' Boom-Boom. I like to think the colony-builders advertised it as "external pulsed plasma propulsion", and had the Federation fooled for a couple of decades, before they figured out that "external pulsed plasma propulsion" involved sticking an atomic cherry bomb under a payload's proverbial tin cup.

At which point all traces of their existence were erased, because nuclear bombs of every sort are evilbadwrong.

[toysdream]

Most of the colony construction materials were obtained in space (from asteroids, the lunar surface, etc). Rocketing all that stuff up from Earth's gravity well would be idiotic, so it's not surprising they didn't do it.

-- Mark

[Zeonista]

Most of the colony construction materials were obtained in space (from asteroids, the lunar surface, etc). Rocketing all that stuff up from Earth's gravity well would be idiotic, so it's not surprising they didn't do it.

-- Mark

Yes, that's one of the reasons I liked UC Gundam in the beginning of my fandom. Why spend endless time on repeated rocket & shuttle launches, when a few big asteroids can be sent to the Lagrange points and the Lunar orbit? Not to mention the fact that the necessary mining, construction, and deployment of all those rockets & shuttles would have undercut the Green movement behind the colonization of the earth Sphere in the first place.

In regards to shuttle & HLV launches, i have been of the personal opinion (in lack of contrary evidence) that the chemical composition of the booster rockets had been tweaked to allow for better fuel efficiency. Scientific progress, etc etc. I also noted that the shuttles and "space plane" systems were designed to make the best use of fuel. For instance in CCA the shuttle used a rail launch system to give added acceleration without using a big fat primary booster.

[Zerosystem]

This is really late and doesn't really add much to the conversation, but the shuttle in CCA still had a fairly large booster stage as well as a propellant tank that probably also had thrusters on it.

About 10:26 into the movie, you can see it separate - the booster is several times larger than the shuttle itself. At 9:50 and 10:12 or so, you can see a top view of the shuttle, which is just at the tip of the entire thing. They accidentally miscolored the propellant tank at 10:12 so the entire craft is yellow which probably led to the wrong assumption, but you can see in other shots as well as when they pass 5th luna in the upper atmosphere that the propellant tank isn't yellow but metallic looking.

[MythSearcher]

Most of the colony construction materials were obtained in space (from asteroids, the lunar surface, etc). Rocketing all that stuff up from Earth's gravity well would be idiotic, so it's not surprising they didn't do it.

-- Mark

Yes, that's one of the reasons I liked UC Gundam in the beginning of my fandom. Why spend endless time on repeated rocket & shuttle launches, when a few big asteroids can be sent to the Lagrange points and the Lunar orbit? Not to mention the fact that the necessary mining, construction, and deployment of all those rockets & shuttles would have undercut the Green movement behind the colonization of the earth Sphere in the first place.

In regards to shuttle & HLV launches, i have been of the personal opinion (in lack of contrary evidence) that the chemical composition of the booster rockets had been tweaked to allow for better fuel efficiency. Scientific progress, etc etc. I also noted that the shuttles and "space plane" systems were designed to make the best use of fuel. For instance in CCA the shuttle used a rail launch system to give added acceleration without using a big fat primary booster.

The UC method was first proposed in Gundam Century, which basically is in turn proposed a bit earlier in L5 news(they actually quoted L5 society), which basically just reported G.K. O'Neil's space colonization plans on mining from the Moon and launching materials with mass drivers and catching them with a mass catcher, then sending them out to L5 for contruction(you can search for the plan online, pictures are pretty cool.).

[Zeonista]

This is really late and doesn't really add much to the conversation, but the shuttle in CCA still had a fairly large booster stage as well as a propellant tank that probably also had thrusters on it.

About 10:26 into the movie, you can see it separate - the booster is several times larger than the shuttle itself. At 9:50 and 10:12 or so, you can see a top view of the shuttle, which is just at the tip of the entire thing. They accidentally miscolored the propellant tank at 10:12 so the entire craft is yellow which probably led to the wrong assumption, but you can see in other shots as well as when they pass 5th luna in the upper atmosphere that the propellant tank isn't yellow but metallic looking.

I forgot the primary booster part, although the rail launch system seemed a lot better than the one I watched as a kid several times.

MythSearcher: Yeah, the UC pretty much copy-pasted O'Neill's ideas and replicated them. It allowed for a fairly solid background to the space story, which gave everything else a good framework. The amount of detail gone into by Gundam Century was impressive, wasn't it?