Orion aka "Ol' Boom-boom"

[Der Kosmos]

I cant help but feel those cannons are not mounted in optimal positions.. i guess the recoil of a 5 inch wouldn't greatly affect a ship of that mass, but it's not 'centred' enough when I look at it :S

It looks centered at more or less the center of mass to me.

[nyrath]

As for the Howitzers, what exactly do they look like? I hear them mentioned a lot, but never any pictures? Where are they mounted exactly?

The howitzers are still classified.

Scott Lowther (the guy who drew the blueprint) has a reconstruction his Aerospace Projects Review vol 2 no 2 along with all sorts of interesting details. He has them looking like stubby tubes, with two of them mounted on the "ceiling" above each gun turret. The rounds look like stubby cylinders with a "pancake" solid rocket on the rear (with the proportions of a hockey puck).

[Canopus]

I love the "spear of nuclear flame" description. Sounds so badass.

[nyrath]

The engine and cartridges work fine. The only thing i disagree about is the difference in weight of the cartridges. I can imagine that a 15 kt bomb is heavier than a 1 kt bomb, but i can't imagine it to be 25 times the weight.

Yes, now that I look at my notes that does seem a bit high. I have a mention of a 29 kt charge (with no figure for the thrust) that has a mass of only 1.15 ton, which is way lower than the 3.68 tons I interpolated for the 15 kt bomb. I wish they would declassify some of this.

I'll lower the mass of the 15 kt and 5 kt magazines after trying to figure a better interpolation.

[nyrath]

I cant help but feel those cannons are not mounted in optimal positions.. i guess the recoil of a 5 inch wouldn't greatly affect a ship of that mass, but it's not 'centred' enough when I look at it :S

I tend to agree. In the rear section, see all those little hemispheres? Those are the pulse drive units, each one full of plutonium, depleted uranium, and tungsten, and about one metric ton apiece. This means the ship's center of gravity is going to be close to the rear section, if not centered in side it.

Which means of you want the cannons to be in their optimal position, they too should probably be in the rear section.

However, that has other problems. So they probably have the cannons mounted in convenient positions, and use RCS to deal with the recoil.

[TheCardinal]

An other peculiar thing. The part consisting of six columns of cartridges contain 600 nukes, while a single cartridge contains 60. In other words, the sixcolumns should contain 3600 nukes instead of 600.

[nyrath]

An other peculiar thing. The part consisting of six columns of cartridges contain 600 nukes, while a single cartridge contains 60. In other words, the sixcolumns should contain 3600 nukes instead of 600.

Yes, because that was modeled after the USAF 10 meter Orion design, which has the distressing characteristic that its thrust to weight ratio is about 0.5. The USAF was supposed to be launched on the top of a chemical Saturn V booster.

The multimagazine part is intended for casual KSP players who want simple ease of play, the look of the Orion ships they've seen in books, and the Jebidiah thrill of lifting off under atom bomb power. More serious player will use the individual magazines.

[Hremsfeld]

I did some quick digging to try to see if there's a declassified formula for determining the yield of nuclear devices; I didn't find one, but the nuclear weapon yield page on wikipedia says the theoretical maximum yield/mass ratio for thermonuclear devices is 6 megatons per metric ton, or 25 terajoules per kilogram. There's also a nice link to the probably-not-official nuclear weapons archive page for the B41, which had the best yield/weight ratio for an american device. Seeing as KSP is idealized in terms of everything-works-until-hit-really-hard, this might be a decent ratio to use for your interpolations.

[Der Kosmos]

Another thing about the blueprints I noticed. There is a spin gravity section. This seems like a really bad idea. Not only is the diameter criminally small, it doesn't jive with the 4g+ acceleration the Orion drive would give. Everything would be sideways and under several gravities of stress.

[Canopus]

Another thing about the blueprints I noticed. There is a spin gravity section. This seems like a really bad idea. Not only is the diameter criminally small, it doesn't jive with the 4g+ acceleration the Orion drive would give. Everything would be sideways and under several gravities of stress.

Could you show it to us? I never saw it.

[Der Kosmos]

Could you show it to us? I never saw it.

Sure, pay attention to the direction the men are standing, the orientation of the ladders, and the shape of the decks.

The 10 meter orion also has this problem, but it's less of an issue. As Nyrath pointed out, it only has a .5 twr.

Another possible design flaw, putting the ladders in a straight stack. Imagine falling from that high at 4Gs!

[Canopus]

I don't think the 10 meter Orion has a centrifuge.

[nyrath]

I did some quick digging to try to see if there's a declassified formula for determining the yield of nuclear devices; I didn't find one, but the nuclear weapon yield page on wikipedia says the theoretical maximum yield/mass ratio for thermonuclear devices is 6 megatons per metric ton, or 25 terajoules per kilogram. There's also a nice link to the probably-not-official nuclear weapons archive page for the B41, which had the best yield/weight ratio for an american device. Seeing as KSP is idealized in terms of everything-works-until-hit-really-hard, this might be a decent ratio to use for your interpolations.

The trouble is that the amount of tungsten propellant is variable as well. That's why the 2MN and 3.5MN charges are both 1 kiloton. Same amount of plutonium, same blast, but different masses and impulse because the amount of propellant is different.

Another thing about the blueprints I noticed. There is a spin gravity section. This seems like a really bad idea. Not only is the diameter criminally small, it doesn't jive with the 4g+ acceleration the Orion drive would give. Everything would be sideways and under several gravities of stress.

Yes, the diameter is too small.

The USAF and NASA 10 meter Orions also had spin gravity. But they did not spin on their thrust axis (the roll axis) nor did they have a centrifuge. They were "tumbling pigeons" (spinning around the yaw or pitch axis). That gives them a spin radius of something like 25 meters.

http://www.projectrho.com/public_html/rocket/artificialgrav.php#id--Tumbling_Pigeons

They (and probably the battleship Orion) would stop spinning when they had to thrust. In the battleship Orion, you are not going to be walking around under 4g. You strap yourself into an acceleration couch (that may appear to be on the wall under spin grav), and ride it out.

Example of "tumbling pigeon"

Example of centrifuge (note long arms)

Edited June 10, 2013 by nyrath

[Der Kosmos]

Ahh that makes much more sense. I'm wondering why the hab module bulges out like that in the 10m Orion then.

Overall, I think I'm tired of seeing centrifuges in spaceship designs. Tumbling pigeons are so much more efficient. It gets really bad that artists just slap a spinning part onto a ship so they can call it "hard sci-fi" without considering the mechanical complexity involved. The only ways to get spin gravity that don't involve absurd arrangements of joints and axles are: Spin the whole spacecraft, which is only really a good idea for immobile habitats ;put the spin section on tracks inside a pressurized chamber, which limits the size of the spin section; and the tumbling pigeon. The Pigeon is such a great idea because there are so many different ways to implement it, and you don't have to balance both halves perfectly. You can just put the lander on one end of a cable, the transfer stage on another, and fire the RCS thrusters until they start spinning. Boom! Instant pseudo gravity.

[Canopus]

I'm wondering why the hab module bulges out like that in the 10m Orion then.

In order to produce the same amount of gravity in a larger place,

[nyrath]

Ahh that makes much more sense. I'm wondering why the hab module bulges out like that in the 10m Orion then.

If you look closely at the Tumbling Pigeon diagram, the pointy part that does not bulge out is labeled "Power flight station/escape vehicle (shielded)".

The question is not why the hab module bulges out like that, the question is why the flight station does not bulge out.

The answer is three fold:

[1] the flight station contains the radiation "storm cellar". Due to the huge hit to the payload budget imposed by the dense walls of the storm cellar, you want the internal volume of the storm cellar to be as small as possible. This tends to make the flight station design with a narrow width.

[2] the flight station is also an escape vehicle. There are a ring of liquid fueled rockets where the flight station attaches to the hab module. There is limited room for fuel, so the flight station has to be as low mass as possible.

[3] the flight station has its decks arranged so that the crew is walking on the floor (and not on the ceilng) while the vessel is accelerating. While doing the tumbling pigeon, the crew would be walking on the ceiling.

The hab module has decks so you walk on the floor while doing the tumbling pigeon.

In the mission profiles for a Mars mission, the vessel will typically spend far more time doing the tumbling pigeon compared to the time thrusting. So the module inhabited while tumbling has a larger percentage of the habitable space compared to the module inhabited while under thrust.

In order to produce the same amount of gravity in a larger place,

Correct!

[Der Kosmos]

Ahh interesting. I didn't realize that.

So put your hitchhiker containers upsidedown when you build your Orion!

[pip12345]

Nova, when is this amazing piece of art going to be released?

I... cant... wait... any... longer...

[Der Kosmos]

Hmm, that pic is giving me an idea. Radial parts that fit around an L sized piece to make it fit an XL sized piece. They parts would be sort of slice shaped so when you put 8 of them around an L part it adds up to an XL part.

[Vaccer]

Doing some "tests", this thing is massively op and I love it.

[nyrath]

Doing some "tests", this thing is massively op and I love it.

Yow! Am I reading that correctly? 600 kilometers per second? A full two percent of the freaking speed of light? Was that a full loadout of sixty 400MN magazines, and you burned them all?

Blasted thing is a starship.

I hope your cryogenic hibernation gear is working, Aldgas Kerman.

Edited June 11, 2013 by nyrath

[NovaSilisko]

Don't know when I'll release orion. Stupid thing just spins while in orbit for no reason, depending on your current roll. At certain angles it will start spinning at something like 5 degrees/sec and others it won't move at all. And it spins on launch, and while using radial engines, for no damn reason.

A full two percent of the freaking speed of light?

0.2%...

Edited June 11, 2013 by NovaSilisko

[nyrath]

Ah, dropped a decimal point again. But still, 0.2%c ? That's smokin'

[Der Kosmos]

Aldgas Kerman joins the E-2 club.

[Vaccer]

I probably could have gone a little faster if I did a full orbit to my periapsis and going full nuke drive prograde but I couldn't turn the blasted thing because no rcs system. Took forever to get past the 100k-200k m/s mark but when I got down to about 1600 left of the 3600 nukes the speed started rising immensely.

Also he's pretty much on a one way trip to the nearest star system with no way to retrieve him since after running out of nukes I let him keep going for about a simulated year on timewarp.

Edited June 11, 2013 by Vaccer