Project High Velocity Interplanetary Passenger Spacecraft

[Izack]

I'm wondering if it might be possible to avoid that compromise (artificial gravity and constant thrust or high thrust and tumbling coast) by simply rotating the vessel around its z axis while thrusting at 0.25/0.5g.
Image (direction of thrust is towards right of image):

The habitation would be inclined somewhat so that local 'up' would point towards a point ahead of the vessel's centreline, so that gravity could be achieved partly by rotation and partly by thrust. Radiator surfaces would presumably be attached to the black truss structure.
Also, if you like puller designs, the whole arrangement can be reversed, so that the direction of thrust is to the left, the tensional structure is a normal one, and the black structure would be a tensional one. This would incur a mass penalty, as the tensional structure would have to be an actual structure and not just a wire. Also a minimum of three hab modules would be required with truss between them, with the exhaust passing between them. Also, additional shielding would be required to protect from exhaust.

This was posted very hastily because I'm headed out the door, so please shoot down whatever flaws you find. :tiphat:

 

[T.Neo]

I don't like it- there is added potential for something going wrong in all those modules. And shielding from the exhaust; exhaust hitting the actual structure of the ship is something that must be avoided at all costs. It'll probably need reflective shielding of some kind though.

If we're assuming an exhaust dissipation angle of 45 degrees, the structure would end up being pretty strange.

Also, if the centrifuge modules are angled slightly, does that mean that everything feels like it's at an angle if the engine is off? What about in the event of the engine being on but the craft not spinning? Are the hab modules on a gimbal of some sort?

Also; 0.25 to 0.5 G isn't that bad- to get up to 200 km/s would take 11 hours at 0.5 G, 22 at 0.25 G. While 22 hours might be a tad long, this is still a sizable acceleration- still more than lunar gravity, actually. A continuously spinning spacecraft would be more suited to say, a 0.05 G acceleration, maybe, like with the Discovery II.

 

[Sky Captain]

From engineering point of wiew I think it would be advantegous to go for less than 1 G for interplanetary craft even if you have technology to build engines capable of doing 1G brachistochrone flight. Think of it:

Engines capable of giving 0.1 G acceleration will be lighter than 1 G engines. Suppose you need 10 engines to accelerate at 1 G and each engine is 100 tons. now you choose to accelerate at 0.1 G and now you can remove 900 t of engine mass from your ship. Also such high performance fusion engines are likely to be VERY expensive so less engines = less cost.
Structure for 0.1 G ship will be lighter than structure for 1 G ship
You can use the saved mass to carry more cargo.

Sure, you will have to burn longer to achieve cruise speed, but does it really matter? 3 weeks flight time or 4 weeks (just a random guess) to Mars. Both figures are super fast compared to what would be possible with conventional chemical or nuclear thermal rockets.

 

[T.Neo]

Yeah, but 1 G engines provide higher acceleration, which means shorter travel times. And that matters in a passenger vessel. It doesn't matter in a cargo vessel, so those can accelerate at lower speeds, and save on engine and structural mass.

Of course, you save structural mass if you put the main structure of the spacecraft in tension as well...

"Very expensive" is relative. As I said, this is technology that doesn't even exist (yet). So you could very easily have a 120 kilonewton engine, that would be very expensive.

Of course, another rationale is that a powerful can accelerate a light ship fast, and a heavy ship slow. So you might be setting yourself up with a large capability that you otherwise wouldn't have.

3-4 weeks is within the range of near-future electric propulsion, provided we can build a powerplant light enough.

 

[jstowe96]

T.Neo I actually have a small spacecraft ive been working on indrawings that might be able to carry =] just maybe if If make a remodel of my current design for it was meant for fighter escorts. But i might be able to add like a magnetic point were it will latch onto your craft but first you would have to launch from a launch platform and then they could meet together while in orbit moving in at same speeds something along the lines =] Ill scan my drawings now.

---------- Post added at 11:34 PM ---------- Previous post was at 11:12 PM ----------

My so called mini craft or watever you wanna call it it fails hard =]

 

[T.Neo]

Yeah, I have nothing better to do than add a missile-toting mini craft to my problematic spacecraft. :thumbup:

Seriously though, keep on drawing- I see potential.

Just don't end up making ships that drown in their own exhaust stream, like mine.

 

[jstowe96]

ahahaha xD lmao ok =] right now im working on it in anim8or ill upload a pic now has about 6 engines trying to figure out how to slant the cockpit -.- im new to this anim8or thing

---------- Post added at 12:18 AM ---------- Previous post was at 12:13 AM ----------

how can i upload an image from the anim8or -.-

---------- Post added at 12:18 AM ---------- Previous post was at 12:18 AM ----------

oh and do you got like msn so we can talk?

 

[T.Neo]

how can i upload an image from the anim8or -.-

Take a screenshot, paste it into MSPaint, save the image, and then upload it to the forums.

oh and do you got like msn so we can talk?

Sorry, I don't got like MSN. We can talk perfectly well on the forums, or if you wish, you can join me in the IRC channel.

 

[jstowe96]

Sorry, I don't got like MSN. We can talk perfectly well on the forums, or if you wish, you can join me in the IRC channel.

Oh ok ill join you once i find it =]

Take a screenshot, paste it into MSPaint, save the image, and then upload it to the forums.

he problem is I have dual moniter when i click on print screen and paste in MS paint it just uploads both screens put together xD

---------- Post added at 12:53 AM ---------- Previous post was at 12:37 AM ----------

Paper editted version

Anim8or version also known as the weird version (first time with anim8or!!!!)

 

[Izack]

Pressing alt+print screen only copies the current window, so you won't have an unnecessarily large picture. Alternatively, you could have just cut out the part of the picture you wanted.

 

[RisingFury]

Thread jacked...

 

[T.Neo]

Thanks RisingFury.

I know jstowe96 is trying, but I most definitely did not invite him to make an auxilliary craft for my spacecraft. And I most definitely did not invite anyone to make an auxilliary craft for my spacecraft that looks like it came out of an episode of Star Trek.

I've been trying to make this ship scientifically plausible for... months, now, and when there is now talk of a vessel with tractor beams, and auxilliary whatchamacallit engines, sidewinder missiles, and landing gear that looks like it would snap upon landing on Phobos, it is more than a little bit disheartening.

 

[jstowe96]

ahahaa lmao yea srry man =P

 

[T.Neo]

Moving on from missile-toting, tractor beam enabled auxilliary craft, but no better in terms of goodness, I figured out that my passengers would get something like 34 times the lethal dose of radiation once the engines were turned on.

Well, it was always supposed to be a relatively "comfortable" ship. At least the passengers will die quickly...

 

[T.Neo]

And moving on...

Attached is an image based on my latest calculations, regarding increased masses, engine and radiator sizes.

Blue- propellant tanks
Green- engines
Purple- rest of the ship
Red- Epic Fail, uh, I mean radiators...

So yeah, HVIPS sucks. h:

 

[Izack]

You have to stop beating yourself up over this. It was a miscalculation discovered a bit late in the design process, but didn't cost any aerospace firm a fortune or anything, and no one died (probably.) Move on with a different design. I'm sure some parts or research from Constell--I mean HVIPS will come into use in a later project.

 

[RisingFury]

and no one died (probably.)

TNeo died inside. :facepalm:

 

[T.Neo]

I'm sure some parts or research from Constell--I mean HVIPS will come into use in a later project.

Funny you mention that. Attached is my latest project; I call it Spacecraft: Lagrange Orbital Worker Platform and Operational Kinetic Extractor, or "SLOWPOKE". :thumbup:

In all seriousness though, RisingFury has a point. My self confidence definitely died as a result of this "miscalculation". :facepalm:

Though I do have a better idea of the powers involved with high specific impulse propulsion, and the math involved...

 

[Tycho6]

...I figured out that my passengers would get something like 34 times the lethal dose of radiation once the engines were turned on.

Well, it was always supposed to be a relatively "comfortable" ship. At least the passengers will die quickly...

Score one for old-school, engines-at-the-back, pusher designs!
Engines at the back with tons of shielding in between, at least. Reminds me of one of the ships from Saturn's Children.

Seriously, though, this was a promising design with an interesting approach. I hope the experience will lead you to a design you're happier with in the future.

As Izack observed, you didn't kill any astronauts, or squander billions on a design that will never fly. So you still have a better record than NASA, or the Russians. :thumbup:

 

[Wonderer]

Or North Korea :thumbup: