Project High Velocity Interplanetary Passenger Spacecraft

[Moach]

i quite like "tumbling ship" design - i find it could be suitable for slower-speed flights, such as hohmann transfers... i find it would be perfect for more conventional moon, or even mars trips....

a similar design was featured in that mission-to-mars fiction/documentary series... it had the engines on the back, tho...

but if you choose to go with less, erm... "radioactive" thrusters (although less dV) you can still safely have a "pusher" design, provided proper shielding....


but most astronauts would probably not enjoy too much sitting at the wrong end of the deathspewer, i guess

and hey, don't beat yourself too hard over it - remember that NASA smashed a billion-dollar rover becaused they mistook feet for meters

 

[T.Neo]

The metric-imperial failure was the [ame="http://en.wikipedia.org/wiki/Mars_Climate_Orbiter"]Mars Climate Orbiter[/ame], not a rover. Still a bad failure, and one of the reasons I dislike the imperial system so much...

I don't really see why you need artificial gravity for a Moon trip that is going to be at most a week long...

The exhaust is not at all radioactive; it is more dangerous in a "ablate the crew module surface and heat up the interior" sense, than the "unstoppable radiation killing the crew" sense. The individual particle energy of the protons in the exhaust is around 700 eV. Alpha particles have energies of around 5 MeV, the lowest energy beta particles have energies of a few keV. So the exhaust is not dangerous in that regard; you can stop it with ease. The problem is the power flux from the exhaust; at that distance, it is something- at the lower bound- 2 megawatts per square meter, which is pretty, uh, uncomfortable.

The problem is the engines, since you can't really put shielding between them and the rest of the ship. If you have aneutronic fusion you can absolve yourself of most neutrons, but no fusion will be free of all ionising radiation.

The problem with a tumbling ship that is a pusher is that the direction of acceleration during spin and the direction of acceleration during thrust is 180 degrees apart, which is a tad... uncomfortable.

Now a pusher spinning on the X axis, with outrigger habitat modules, has an angle between the acceleration of spin and acceleration of thrust of only 90 degrees, which is a tad less uncomfortable. If the ship is set up like that, you can then thrust while spinning as well, which might be more convenient for the passengers.

But then, you just have a passenger version of the Discovery II study... :dry:

 

[Moach]

have you considered a mobile structure instead of a rigid truss?

i mean, if you used cables, you could pull in the cabin module up close to the fuel tanks where it's "safe" - as long as the engines are still mounted on the sides

once the acceleration was complete, you could extend the cabin and start spinning for artificial gravity... well, maybe not in that order :hmm:


the only disadvantage would be no docking while spinning... but that shouldn't be that big a deal :thumbup:

 

[T.Neo]

It isn't safe near the fuel tanks, there you are still not in their radiation shadow from the engines. You want standoff distance from the engines; it can also alleviate the radiation load, as an alternative to shielding.

Depends on if it does so enough, though.

No docking during spinning shouldn't be a problem... it was never part of the design anyaway (an attempt to prevent undue stress on the docking mechanism).

 

[T.Neo]

HTT mass update

I'm shelving HVIPS indefinitely; while it may be possible, a manner in which it could potentially be made practical, at best escapes my feeble mind and at worst, does not exist at all.

She just doesn't learn, and our on-and-off relationship is becoming a source of increasing annoyance. Especially since she asked for some new expensive and impractical thermal shielding. :uhh:

HTT is currently set up for a 20 meganewton engine, which should be able to accelerate 650 tons and an acceptable amount of fuel at over 1G, but this time, wisely, I've included a mass growth contingency. HTT really lacks any practical application other than doing stuff that's "cool"; no payload, no auxilliary vessels, no fancy habitation module. Just an engine, radiators, fuel tanks and a small command module for 2 people.

You can pretty much see by the big red slice on the graph why I hate radiators so much. :dry:

 

[Wishbone]

Ehh, why not drop the "P" letter in requirements, and make her a really fast interplanetary and interstellar UEV (unmanned exploration vehicles') mothership?

 

[T.Neo]

What would that achieve? It's the design that's the problem, not the crew. Also, 500 km/s is slow on interstellar scales... something like 2640 years just to get to Alpha Centauri.

I've been thinking about interstellar ships, but HVIPS certainly did not start out as one, nor could it end up as a (good) one.