Artifical Gravity design - Ship design to create AG?

Lacodia · 2003-08-26 22:44:43

Helix Craft
This craft would travel between Earth and Mars on a helix path, spiraling along a conventional navigational path between the planets. The craft would use conventional propulsion for it's acceleration to Mars.
Small thrusters evenly spaced around a cylindrical outer hall would provide a continuous variable angular thrust, at a right angle to the direction of travel. This would put the craft on a spiral path.
A cylindrical, inner gyroscopic mounted habitation hull would provide a stable 1g artificial gravity environment.
The rotational breath of the helix could be very large, possible as large as 60 miles, depending on the fuel requirements needed to maintain the constant use of the thrusters.
A very large rotational length would allow for a small RPM, thus reducing the Coriolis Effect. It would also establish a uniform gravity from head to foot.
The 1g artificial gravity would be created by the continuous change in angular momentum of the outer hull. The inner hull, mounted on gimbals (diamagnetic bearings are interesting), would insure that it would always be in alignment with the centripedal accelerations.
The advantage is that you are not relying on a tethered system that might break down, and also you would eliminate the cumbersome nature of the rotating wheel, and tethered systems.
As you approached Mars, you could use the thrusters to reduce and then eliminate the helix path, and then enjoy the benefits of a conventional craft design.
Mark

Shaun Barrett · 2003-08-27 00:07:56

Hi Lacodia!
My initial response to this is that you are still accelerating the entire mass of the craft at 9.81 m/sec/sec. You have to be because otherwise you won't get the desired effect in the crewed inner hull.
All you are doing to create the change in angular momentum is trading the inward pull of the tether for the inward push of the thrusters.
There's nothing intrinsically wrong with that of course, except for the continuous high rate of fuel usage in the thrusters. Considering that you're using a standard Hohmann transfer orbit, it's still a 6 month trip. That's a long time to be firing those thrusters! If you were to just aim your craft at Mars and accelerate at 1g, flipping around at the half way mark and decelerating at 1g, the trip would take about 42 hours. (Assuming you waited until Mars was closest to Earth.)
I think the latter method is considerably more fuel efficient! Unless I'm missing something important here.

By the way, a warm welcome to New Mars! You'll have a ball here with some of the discussions.
Most members are great fun, though quite a few of them are politically right out there on the edge. But don't worry. My politics are perfectly normal and reasonable (thank God), so if there's anything you need to know on that score just ask me! OK?

Free Spirit · 2003-08-27 16:03:53

By the way, a warm welcome to New Mars! You'll have a ball here with some of the discussions.
Most members are great fun, though quite a few of them are politically right out there on the edge. But don't worry. My politics are perfectly normal and reasonable (thank God), so if there's anything you need to know on that score just ask me! OK?

Don't be scared away by Shaun's political delusions. Before it's all said and done I'm sure Shaun will come to see the logic of the Green Anarchists and will run with the luddite hordes to burn down every last trace of industrial civilization. Yes, eventually we'll see Shaun kicking back in animal skins and foraging for wild berries out in the jungle. Civilization and agriculture are not compatible with freedom! When will you see the light! ???

Shaun Barrett · 2003-08-27 18:54:29

Free Spirit:-

... Shaun will come to see the logic of the Green Anarchists and will run with the luddite hordes to burn down every last trace of industrial civilisation. Yes, eventually we'll see Shaun kicking back in animal skins and foraging for wild berries out in the jungle. ...

Ha ha ha !! :laugh: What a picture that conjures up .. very amusing, Free Spirit!

Lacodia · 2003-08-27 19:19:46

Thanks for the warm welcome Shaun.
?There's nothing intrinsically wrong with that of course, except for the continuous high rate of fuel usage in the thrusters. Considering that you're using a standard Hohmann transfer orbit, it's still a 6 month trip. That's a long time to be firing those thrusters! If you were to just aim your craft at Mars and accelerate at 1g, flipping around at the half way mark and decelerating at 1g, the trip would take about 42 hours. (Assuming you waited until Mars was closest to Earth.)
I think the latter method is considerably more fuel efficient! Unless I'm missing something important here.?

I?m not a mathematician so correct me if I?m wrong, but I think there is a huge difference in fuel between the two examples, and it favors the helix trajectory.
Lets use a car as an example. One car try?s to maintain a constant 1g effect on it?s passengers by constantly accelerating in a straight line. It?s obvious that before long it would be approaching the speed of light and consume a massive amount of fuel. On the other hand, the other car swerves in an ?S? shape pattern along the meridian, all the while maintaining a constant speed. Its passenger is thrown two and fro, but instead, imagine that the seat is mounted on gimbals. The passenger now experiences a smooth and constant g force!
A mathematician might want to calculate the necessary thrust needed to maintain such helix trajectory. Solar and nuclear fuel might be able to maintain this thrust over long periods of time!
Mark

mcshlong · 2003-08-27 20:00:21

Uh theres a big differance between acceleration and centrifical force.

For one thing once you get the thing spinning you won't need to continue to fire the rockets. It should spin almost forever supplying the 1 g you need. Being that big you wouldn't need it spinning very fast at all.

Lacodia · 2003-08-27 20:43:57

Hi mcshlong,
It doesn't actually spin. The vessel would maintain it's orientation to the flight path just like any normal vessel would. However, the helix vessel would spiral around the flight path like watching a sidewinder missile does. It would maintain its orientaion but would spiral around a central axis. Instead of using a tether tied to a counter wieght, it would use a large number of thrusters arrayed around the outside of the cyclinderical body, with each logitutal array firing in order (or several of them) so as to cause the vessel to loop or spiral around this axis.
Inside, there would be a gimbals mounted inner hull, which would smoothly keep its orientation with the continously changing firing thrusters. Thus maintaining a constant g force in the habitation inner hull.
By having a very large spiral radius, you minimize the undesirable coriolis effects.
Think a tethored vessel traveling to mars, but just replace the tether and anchor with inward pushing thrusters. The great advantage here, is that you are essentially using a somewhat modified conventional vessel instead of some large three piece cumbersome accident waiting to happen vessel.
Maybe this weekend I'll post some sketches of the helix vessel idea on my website.
One concern I have is this: Does it make more since to have a double hulled vessel, with the outer hull logitutually stationary, and the inner hull mounted on gimbals, or, use a single hull design with the hull itself spinning? Using just one set of logitutal arrayed thrusters.
I think the double hull makes since for a variety of reasons:
1. It provides a stationary outer hull for mounted equipment like sensors, navigational and communications equipment.
2. It makes it easier for docking ships to dock.
3. The double hull, provides a great opportunity to increas protection from radiation, debri, and last but not least.
4. It provides a vibrational dampending barrier.
Mark

Shaun Barrett · 2003-08-28 01:28:37

Hi again Lacodia.
I think you're attempting to get a free lunch here and I'm afraid it won't work. You're trying to maintain a 1g centripetal force on your astronauts using small thrusters expending minimal fuel.
"For every action there is an equal and opposite reaction". In space this law is more apparent than anywhere on Earth. If you've got astronauts bearing down on the floor of your spacecraft with an acceleration of 1g, you have to have 1g of thrust, in the opposite direction, under the floor of that craft. There's just no getting away from it. And that's going to cost you just as much fuel per second as accelerating in a straight line, except the journey's taking you much much longer.
Your car-on-the-ground analogy doesn't help either because there you're relying on friction between the tyres and the road to provide the centripetal acceleration. Your energy losses would be enormous, by the way, but that's not the main problem with the comparison. In space there's simply nothing to push against. You have to provide all of the acceleration and the only way to do it (at least as far as we know today) is good ol' rocketry!

I really and truly hate to rain on parades and I have to say your idea is one I've never come across before (full marks for originality! ) but it relies on something-for-nothing when you analyse it. The laws of physics are ruthless when it comes to that sort of thing and, however hard you try to get around them, they always make sure you obey .. one way or another!

Gennaro · 2003-08-28 05:29:58

I must say, because I'm not English speaking and not an expert on any of these matters, I might just have misunderstood the proposed design. Are we talking a simple cylindrical shaped life support section in rotation on a fixed frame, or something else?
(Can't wait to see those sketches, Lacodia! )

In any event, why rely on thrusters (and fuel) to provide centripedal motion at all? Couldn't a small nuclear reactor create enough electrical power to do the same thing? What about the cores of a nuclear thermal rocketed spaceship, other than providing thrust at the beginning and end of an interplanetary journey? Most of it is coast with the rockets shut down anyway, is it not (and it's precisely then, when you are not accelerating that you put the artificial gravity system in operation, yes?)?

SpaceNut · 2021-08-07 08:05:06

bump large ship AG...

RobertDyck · 2021-08-07 08:57:23

Interesting. This discussion mentions a helix craft, not a wheel. Remind you of the 2016 movie "Passengers"? Did someone read this discussion?

SpaceNut · 2022-01-23 14:25:37

bump

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#1 2003-08-26 22:44:43

Re: Artifical Gravity design - Ship design to create AG?

#2 2003-08-27 00:07:56

Re: Artifical Gravity design - Ship design to create AG?

#3 2003-08-27 16:03:53

Re: Artifical Gravity design - Ship design to create AG?

#4 2003-08-27 18:54:29

Re: Artifical Gravity design - Ship design to create AG?

#5 2003-08-27 19:19:46

Re: Artifical Gravity design - Ship design to create AG?

#6 2003-08-27 20:00:21

Re: Artifical Gravity design - Ship design to create AG?

#7 2003-08-27 20:43:57

Re: Artifical Gravity design - Ship design to create AG?

#8 2003-08-28 01:28:37

Re: Artifical Gravity design - Ship design to create AG?

#9 2003-08-28 05:29:58

Re: Artifical Gravity design - Ship design to create AG?

#10 2021-08-07 08:05:06

Re: Artifical Gravity design - Ship design to create AG?

#11 2021-08-07 08:57:23

Re: Artifical Gravity design - Ship design to create AG?

#12 2022-01-23 14:25:37

Re: Artifical Gravity design - Ship design to create AG?

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