Subject:
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Re: Where's all that gravity coming from?
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Newsgroups:
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lugnet.space
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Date:
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Fri, 9 Mar 2001 07:27:57 GMT
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Viewed:
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678 times
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J.D. Forinash <foxtrot@cc.gatech.edu> wrote in message
news:9889lg$s7$1@anagram.bufordnet.foo...
> In article <G9v9or.19J@lugnet.com>, Damraska <Damraska@Excite.com> wrote:
> > I considered and discarded that methodology, but upon reflection, I • cannot
> > think of a good reason why. It could work. The probability of something
>
> It does have the annoyance that spinning up/spinning down affects both • parts
> of the ship, so you have to use small thrusters to get pointing in the • right
> direction before you can fire the main engine.
>
> This, interestingly enough, has a neat side-effect, I think: Since the
> "non-rotating" section actually rotates, why not make it identical to the
> rotating section? It would then rotate the same speed the other direction,
> and, well, centripetal force doesn't care which direction you rotate. You
> have to be careful in the hub going from section to section (as the • rotational
> speed from there looks like _twice_ what you'd guess...), but it's • probably
> do-able. Though maybe not in Lego-- I can't think of a rotation mechanism • in
> Lego that doesn't involve something at the center of the hub, which • implies
> axles, which are now counter-rotating and happily decapitating our • minifigs
> as they try to move between arms.... Perhaps you just don't switch arms
> while spinning...
How about this: build a large drum (or box) with arms attached to opposite
sides. At the end of each arm resides a habitation module. When stationary
(or simply not accelerating), the arms pivot outward from the drum and you
spin the whole ship. When thrusting, the arms pivot down, flush with the
sides of the drum/brick. Airlocks on the ends and sides of the arms allow
entry into the central hull depending on the position of the arms. The arms
and habitation modules suffer stress along the same axis in both modes of
operation. Come to think of it, when I was a little kid, I had a very, very
cool space station model that used just this design. When folded, the whole
space station was cylinder. After reaching orbit, three leaves folded out,
away from the central body. Each leaf comprised a habitation module (with
many decks). The central tube contained fuel and the thrusters.
You could also build a ship with three components: central drive, fuel
module, and crew module. Under thrust, the fuel and crew modules sit on top
of the drive. When stationary (or not accelerating), you spin the drive and
reel the other two modules out on tethers in opposite direction.
Another possibility is building a ship with two booms and two drives. The
drives are connected to one another like a dumbbell. Both arms spin on the
connecting axel. Under thrust, the arms both point down, side by side.
Otherwise, the arms spin around the axel, seperated by 180 degrees.
<whirr chop>
> If I remember my particle dynamics correctly, the amount of energy it • takes
> to get a hydrogen particle from stationary to velocity V is equal to the
> amount of energy it takes to get a hydrogen particle from stationary to
> velocity V no matter when you do it, at the start or in the middle of
> space. It's not an issue of how much energy can you get from the • hydrogen--
> it's an issue of "You're gonna have to accelerate this hydrogen anyhow."
> Which is heavier, the bigger hydrogen tank or a Bussard scoop, figuring
> that you have to either a) collect all the hydrogen you need to slow
> down (read: half of what you need total) or b) have a Bussard scoop that
> you can point in the direction opposite of your thrust, which seems even
> more fragile than some of the other stuff? And even so, decelerating,
> once you get slow enough it becomes approximately useless anyhow.
>
> Basically, a Bussard scoop saves you half (ish) of what size your hydrogen
> tanks need to be.
Check check. It makes sense as a break/self replenishing fuel supply but
that's about it. So much for my wonderful math skills.
> > anyway. Any minifigs planning such a trip should expect in flight delays • in
> > advance--perhaps a dew decades.
>
> True. Which brings us to another real problem with minifig space travel: • how
> do you keep your blue ship from turning yellow over the decades? The • thread
> in .general implies it's not sunlight that yellows bricks. :)
Maybe the cold of space will inhibit the chemical reaction. Or accelerate
it. Or cause parts of the superstructure to congeal into POOPs and BURPs.
> > I guess you could make the crew spaces a sphere inside a sphere, but
> > building that in lego at minifig would be ugly. A box inside a gyroscope
> > would work.
>
> But still has the shielding problem-- after all, the more stars we spend
> time near, the more high energy particles hit our poor minifigs. Also,
> given the fact that these primitive ships would be heading toward close • stars,
> chances are slingshotting won't get us much except maybe a decent way to • slow
> down on the other end.
I guess the shield could sit on top of the sphere, sort of like a mushroom
cap. I think any ship, no matter what it looks like, can take advantage of
the slingshot to some degree. How about three nested spheres: outer for
the drive, middle for the shield, and inner for the crew quarters. Still
ugly to build.
> > Unfortunately, a sail only catches photons, not high energy particles, so
>
> On the one hand, I want to say, "Well, why not just build it to catch high
> energy particles, too?" but on the other hand, we've already noted that
> that takes heavy steel plates or asteroids, and now we've got too much • mass
> for a solar wind even augmented by HE particles to accelerate us. So a
> smaller shield would indeed be a better idea.
>
> > the need for a shield remains. Maybe solar sailors should take along • some
> > nuclear weapons for added stopping power, just in case.
>
> Why not? They've got the shield already. :)
>
> > I personally lean towards the 3x3x2 rocket cones these days. They seem • more
> > sleek to me.
>
> I'd thumb my nose at you and say, "Ha! What good is sleek in space?", but
> the real reason I use 4x4x2 ones is because I don't have as many 3x3x2
> cones. :)
I have the reverse problem. I only use the 4x4x2s on really big ships
because I just do not have many.
By the way, we left out potentially the most efficient fuel of all:
antimatter. Of course, collecting a usable amount will require a lot of
colliders...
-Doug
Minifig Suns: http://pages.prodigy.net/damraska/
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Message has 2 Replies:
 | | Re: Where's all that gravity coming from?
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| (...) Ooooh, tethers. I like that idea. Though I dunno how to build it in Lego. :) In fact, one could do something like this where both sides are habitation modules, and have an "elevator" that climbs and descends the tethers should minifigs need to (...) (24 years ago, 9-Mar-01, to lugnet.space)
| | | Re: Where's all that gravity coming from?
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| (...) <snip> (...) <snip> You just described my "Extra Stout" space tug - an entry into Mark Sandlin's space contest of this past summer: (URL) only difference is that I didn't rotate the entire ship, just the pods and arms. There's a rotator cuff (...) (24 years ago, 12-Mar-01, to lugnet.space)
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Message is in Reply To:
| | Re: Where's all that gravity coming from?
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| (...) It does have the annoyance that spinning up/spinning down affects both parts of the ship, so you have to use small thrusters to get pointing in the right direction before you can fire the main engine. This, interestingly enough, has a neat (...) (24 years ago, 8-Mar-01, to lugnet.space)
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