3D attempt #2: a rocket

[Destructionator XV]

I tried my hand at 3d modeling again today, for the second time, and while I still suck, I think I did get at least the very most simple basics down, so I tried to make a rocket design.




The spheres and the cone would be the pressurized crew area: the sphere arm rotates to provide artificial gravity. The rest of the rocket would be used for cargo and fuel. It should also have heat radiators, but I suck at this art thing.

I rather messed up the sphere arms connecting them to the cone, but other than that, it doesn't look half bad. At least for just a second attempt at it.


Third attempt, work in progress:
EDIT: pics deinlined, see a few posts down for the more final product
http://arsdnet.net/rocket3.jpg
http://arsdnet.net/rocket4.jpg

I am much happier with this one. I figured out cut and paste and how to basically snap to the grid, which gives this one much more precision. I also switched to a torus (which was a bitch to make) from the balls, since I know how to make it now, and it is probably a better design for the rocket anyway.


And a couple more hours of my precious life wasted away gives this:

EDIT: pics deinlined, see a few posts down for these shots refined and drawn to scale
http://arsdnet.net/rocket5.jpg
http://arsdnet.net/rocket6.jpg
http://arsdnet.net/rocket7.jpg

Changed to three smaller engines instead of one, and added the heat radiators. Also figured out color, so you can see the radiators and rocket nozzles glowing. And figured out the background, so added one more appropriate to a space rocket.

I think that is looking really good.

So the wheel is the where the rocket is?

The rockets are only visible in one of the color pictures - the first ones, glowing blue. The wheel is at the front of the rocket, far away from the reactor to serve as a part of protection against radiation.

a) why are the crew areas in the first design spherical/conical, and

Because I didn't know how to make a ring :P

That is just about the only reason for it. Though spheres can actually work for it: spheres are good shapes for maintaining a constant atmospheric pressure and are cheap and easy to build. If the whole length of a ring isn't needed for the ship's function, some spheres on rotating arms can possibly do the job while massing less.

b) unless the thing is HUGE, where are the crew areas in the third/fourth take period?

They would be in the ring and the nose capsule of the ship. This isn't really to scale; I just wanted something to draw to learn how to do it, but the ring should be big enough for most their needs.

For a pressure differential of one lousy atmosphere is that really an issue?

It is just simply that gas easily fits in a spherical shape evenly distributed, which allows the sphere to be made lighter. The ring works well for this too, but also has tradeoffs in surface area (relates to radiation exposure and shielding).

Why would they be any cheaper or easier to build then, say, a cube?

If the ship is constructed in space, molten materials tend to naturally form spheres without any effort.

Which would have the advantage of NOT having a curved floor?

Actually, that is a disadvantage. Remember it rotates for artificial gravity. "down" would be toward the outside of the rotation. Obviously, the outside of a rotating object would form a circular shape, so a circular floor means you can walk around the whole thing while always feeling the same "gravity".

That is the reason why all space colony designs are either spheres, cylinders, or toruses.


Now, if it wasn't rotating, then a cube would be just fine, but then there would be no gravity unless the rocket was constantly firing with significant thrust (which would expend a great deal of fuel very quickly).

There is no scale for it to be TO anyway, that was mainly a nitpick.

Well, I could have crunched some numbers for the amount of "gravity" in the ring given a size and then based radius and length of the cylinder body on a calculated mass. I do intend to do just this eventually, but it wasn't a goal while learning how to use the 3d modeling program.

But the radius of the ring would be somewhere around:

r = a / w^2 where a is desired centripetal acceleration, r is radius, and w is angular velocity. For moon gravity (1.6 meters per second squared), which is enough to let people operate pretty normally (although, they will still need to exercise to keep their muscles up) and a rotation of 2 rpm (anything more and people start to get dizzy due to coreolis effects),

r = 1.6 / .21^2 (second number is 2 rpm converted to radians per second), giving 36 meters. That is certainly doable for the ring's radius, although it sounds big compared to ships we build today.

It just seemed to me that you were going for a more or less realistic approach for a space station.

Right. It is basically a mobile space station, possibly something that would be useful for sending men to study Mars or something like that.

If the rings are habitable, the station dwarfs anything mankind has done so far something fierce (and anything mankind will do in the foreseeable future at the rate we're going).

Well, we have built rockets quite big. The Saturn V that boosted Apollo into space had a radius of about 10 meters and a length of about 110 meters. Of course, a great deal of this was staged fuel tanks, but if we assembled my ship in orbit, we could certainly do it.

Let's play with some numbers. Suppose my rocket has dimensions similar to the space shuttle: 9 meters wide, 55 meters long. Suppose the ring's internal diameter (the "height" of the room the occupants would see) is 4 meters (3 for internal space, and one for radiation shielding).

Each connecting arm for the ring must be 19 meters long to give it the size for our acceleration. Pretty big, but nothing that can't be done.

Let's assume the density of the whole thing is that of water (1 ton per cubic meter. The space shuttle is actually about 1 / 2 this, so consider this more of an upper estimate number, and we are fudging some specifics anyway) and see how much it would mass.

The body would have a volume of about 3500 cubic meters. Let's say the connecting arms are also cylinders with a radius of one meter (plenty big enough for a man to walk or crawl through; they could probably be much smaller). That would give about 60 cubic meters each, and 4 of them, so 240 m^3.

And the ring is a bunch of circles spun about an axis. Each circle would have area of pi r squared, r is 2, so area is about 13 square meters. The circumfence of the ring would be diameter of 68 times pi, so 214 meters. Area times circumference will give volume of the torus (this is due to a calculus technique called volume by discs. Technically, I would integrate area through circumference, but it is a trivial operation for this case being the same as multiplication): 2800 cubic meters.

So the total is 2800 + 240 +3500 = 6540 cubic meters, and with our assumed average density, 6540 metric tons. It would take 260 space shuttle flights to get this ship into low earth orbit! Only 55 Saturn V flights. It would be very expensive to launch given the launch technology we have right now, but it would be possible. If we built an Orion launcher (possible since the 1950's, but canceled because it used nuclear bombs for propulsion and a treaty forbade it), it could go up in one stage. There are also other potential rocket designs, like the Sea Dragon that could cut costs as well, but I am digressing. A better plan for constructing a ship like this would be to build it in space out of lunar or asteroidal material, but that of course requires space infrastructure in place first. (Not a problem for most sci-fi societies, however, since they do indeed have space manufacturing plants in place generally).

EDIT: also, with these numbers for the ring, assume a person takes 30 cubic meters of space in there. We have about 1400 cubic meters of people space and about 670 square meters of floor space in there. This could comfortably carry about 50 people on long (multi year) research trips. In fact, it could hold far more, as 30 cubic meters is more than I had in my college room, but people like to have space on long trips. Their food, water, and other supplies would be carried in the cargo / fuel cylinder, so no need to worry about it for this calculation (it is big enough to last a long time. Consider a man eating 1 kg of food a day. 18 tons would last 50 people a full year, which would easily fit back in that cargo section of 3500 tons. Water would be almost perfectly recycled (chump energy for a nuclear reactor), so not much need to worry about that) /edit


So, doable with today's technology, just prohibitively expensive to launch.


And some shots of it redrawn to the scale I described above.










But giant mirrors wouldn't be very useful on a nuclear powered mobile research station.

But an antenna certainly would be. As would a more detailed docking port. And an external cargo access section. And a telescope. And windows / viewports on the ring. And some new colors and textures. Lots of cool stuff.

I am thinking about separating the cylinder into two sections too: the back end with the radiators, the reactor, the fuel tanks, and engines, then have some area between that and the next section which would be the cargo section and of course the nose and ring. That would be pretty cool. Perhaps warp nacelles if it is a sci-fi FTL ship. Then do an internal diagram in 2d of course.

Time to crunch some numbers on how much power would be needed to make the reactor and radiators to a more realistic scale as well.

I might also see about modeling a warship next. Some obvious differences would be it wouldn't have a big ring yelling SHOOT ME but it would have coilguns and laser cannons.