GENERAL DISCUSSIONS

How gravity regulation works?

POSTED BY: CREVANREAVER
UPDATED: Wednesday, February 21, 2007 13:48
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Wednesday, February 21, 2007 2:22 AM

DONCOAT


Drostie, after your first post I was going to make a snarky comment about killjoys and such, but I see you've joined the game. So, welcome!

I have one question, though. Where did you get the idea that the main engine was some sort of nuclear explosion? I don't recall that being suggested in any of the canon or even in the RPG. Is it just something you assumed based on its appearance?

As far as I recall, the only technical description of Serenity's drive is "standard radion accelerator core", which is ambiguous at best. Still, one doesn't normally describe a nuclear explosion as an "accelerator", even though it is rather effective at accelerating things.


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Wednesday, February 21, 2007 7:30 AM

CITIZEN


Hi Drostie.

Personally I like thinking about this stuff. With Sci-Fi you're going to have to make some assumptions and leaps at some point, most of the time this is in the form of FTL travel and communication and Artificial gravity. The important thing is too limit your assumptions and fantasy and to keep them internally consistent. The more you can draw in real science the easier it is to remain internally consistent.

That and as I said some people just like talking about this stuff.
Quote:

Originally posted by Drostie:
On a plus note, I'd be optimistic and identify the two side engines of Serenity as ion drives. In 500 years, we might manage to make them practical. Probably, the engine involves a contained fusion reaction -- and "core containment" refers to the inevitably large amount of radiation that needs to be kept away from the crew manning the ship.

It appears to operate as an air breathing Jet engine in an atmosphere, there's a number of explanations but I wonder if it runs as a Jet engine at low velocity atmospheric flight and can reconfigure it self in flight to operate as a Ramjet or Scramjet at higher speeds before switching too rocketry for non-atmospheric flight.

The problem with Ion drives is that despite their efficiency they have theoretical maximums that prevent them achieving high thrust. In fact a standard Hydrogen-Oxygen Chemical Rocket can produce nearly 3 times the thrust of the theoretical Ion maximum.
Quote:

Again, the "nuclear explosion" tail-end drive is highly unrealistic, because people are on a scale where Newtonian mechanics holds very well, and human bodies don't take kindly to being accelerated at rates greater than a couple g's. Possibly, genetic engineering will improve those accelerations in the intervening years, but not to the level that they're talking about. In any case, we see people habitually stand when the acceleration is done (e.g. Jayne's "Let's moon 'em" comment), when the accelerations involved would probably toss them off of their feet.
Well they have artificial gravity, there's no reason the same system can not be used to counteract the crews inertia, of course as far as we know that level of Gravity control is probably impossible, certainly implausible, but it is internally consistent . I don't know if I've mentioned this already but I quite like the idea of Serenity's interplanetary drive being a form of an Inertial Confinement Fusion Drive.



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Wednesday, February 21, 2007 8:44 AM

COZEN


Quote:

Originally posted by citizen:
...an Inertial Confinement Fusion Drive.



Okay, I admit from the get-go that I know nothing about all of this, and thus am unable to contribute in any positive way to the fantastical -- yet fun! -- speculations regarding the potential to manipulate or conquer gravity 500 years hence. Still, I'm curious about what kind of fuel might be considered as usable to facilitate containable fusion of the variety that can propel a spaceship, such that the cost and space required to carry said fuel in the first place is not an insurmountable obstacle?

Also, I wonder where onboard Serenity is the "gas tank"?

In any case, it appears to me that gravity may or may not be considered to be a "weak" force, but it is certainly phenominally persistent and consistently measurable. And that gravity is symbiotically tied to the mass of objects. Which is why it bothers me that a tiny craft such as Serenity can be (heh!) configured to consistently maintain a 1g gravity for those onboard without somehow burning a huge amount fuel to preserve her passengers' structural integrity, whether or not the ship itself is accelerating.



***
Yeah, carry on without this post, lol!

Mathematically Challenged cozisall

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Wednesday, February 21, 2007 8:50 AM

DONCOAT


Quote:

Originally posted by citizen:
Quote:

Originally posted by Drostie:
On a plus note, I'd be optimistic and identify the two side engines of Serenity as ion drives. In 500 years, we might manage to make them practical. Probably, the engine involves a contained fusion reaction -- and "core containment" refers to the inevitably large amount of radiation that needs to be kept away from the crew manning the ship.

It appears to operate as an air breathing Jet engine in an atmosphere, there's a number of explanations but I wonder if it runs as a Jet engine at low velocity atmospheric flight and can reconfigure it self in flight to operate as a Ramjet or Scramjet at higher speeds before switching to rocketry for non-atmospheric flight.

Such combined-cycle engines have been considered, and are already on the drawing board (conceptually at least). Some people think that an engine of that type may already exist, namely as the power plant for the so-called Aurora black project hypersonic spy plane. (If it does exist it probably does not have full rocket-mode capability. That wouldn't be needed for Aurora, but would be desirable for an advanced space plane.)

The great advantage of that type of engine, of course, is that you don't have to carry any oxidizer for operation in atmo. But we do know that the thrusters can operate in space... I forget which episode shows it, but at least one does. Of course, that could simply have been a mistake by Zoic... but now it's canon, so the game continues.

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Wednesday, February 21, 2007 9:01 AM

DONCOAT


Cozen:

Barring any unforeseeable advances, the likeliest fuel would be deuterium (a heavy isotope of hydrogen), which could be carried as a cryogenic liquid.

Its energy density would be very high. The Hiroshima bomb represented the conversion of less than one gram of mass to energy. The core of the bomb was much heavier, since only a small fraction of its mass was converted to energy. But fusion is more efficient than fission in converting mass to energy.

Matter-antimatter reactions are the most efficient of all -- 100% of the mass is converted to energy -- but it poses a lot of practical problems.

As for the fuel tanks, the extenders could hold a lot (those are the elements that connect the thruster pods to the fuselage; the shuttles land just above them). There's also a fair amount of volume between the inner and outer hulls -- we see that in the opening and closing shots of Objects In Space. Some of that could be used for fuel storage.


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Wednesday, February 21, 2007 9:19 AM

CITIZEN


Quote:

Originally posted by DonCoat:
The great advantage of that type of engine, of course, is that you don't have to carry any oxidizer for operation in atmo. But we do know that the thrusters can operate in space... I forget which episode shows it, but at least one does. Of course, that could simply have been a mistake by Zoic... but now it's canon, so the game continues.

The major difference between a Jet and a Scramjet/Ramjet is that a Ramjet doesn't use a compressor and turbine, so switching from Jet to Ramjet is conceptually simple, you just turn off the turbine compressor. Of course practically it would be quite hard to get an internal configuration that worked efficently for both.

I doubt that the thrusters space born operation is a mistake, the FireFly drive is an interplanetary drive, wind it up and shoot along a straight line trajectory just fine, but they're not so great for fine manuavering such as those required in Orbital space or when docking. Also we know what happens if you light the interplanetary drive in a planets atmosphere from the pilot.



More insane ramblings by the people who brought you beeeer milkshakes!
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Wednesday, February 21, 2007 9:25 AM

COZEN


Quote:

Originally posted by DonCoat:
As for the fuel tanks, the extenders could hold a lot....



Thanks! I like this answer. Just because I'm willing to suspend disbelief in order to facilitate the enjoyment of particular entertainment, doesn't mean I can't still wonder about certain practicalities.

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Wednesday, February 21, 2007 10:17 AM

CITIZEN


Quote:

Originally posted by cozen:
Still, I'm curious about what kind of fuel might be considered as usable to facilitate containable fusion of the variety that can propel a spaceship, such that the cost and space required to carry said fuel in the first place is not an insurmountable obstacle?

A Fission powered Submarine can circumnavigate the globe on a unit of fuel the size of a golf ball. Fusion releases a huge amount of energy from comparatively little fuel. In the case of an IC-Fusion drive this fuel would be a solid pellet of a Hydrogen Isotope, usually deuterium but tritium can also be used.
Quote:

Also, I wonder where onboard Serenity is the "gas tank"?
Probably anywhere there's spare space, but the two semi-circular sections running most of her length are a good bet as fuel tanks, remembering there's probably at least three types of fuel. Fuel for the reactor that powers Serenity, fuel for the thrusters (which may also be used by the RCS) and fuel for the interplanetary drive.
Quote:

In any case, it appears to me that gravity may or may not be considered to be a "weak" force, but it is certainly phenominally persistent and consistently measurable. And that gravity is symbiotically tied to the mass of objects. Which is why it bothers me that a tiny craft such as Serenity can be (heh!) configured to consistently maintain a 1g gravity for those onboard without somehow burning a huge amount fuel to preserve her passengers' structural integrity, whether or not the ship itself is accelerating.
Once a pone a time man looked up and electricity was merely that which was symbiotically linked with thunder clouds. Who'd have thought so long ago that one day we'd bring it down from the clouds and contain it in something as small as a AAA battery. Lightning in a bottle indeed, or at least a Duracell in a walkman.

To take a real basic example photons are admitted when an electron drops energy levels within an atom. Thus light is symbiotically linked with atoms. Suppose there is a Graviton, and the Graviton is the cause of warped space-time and not the mass which emits them. Then one day we may have electric gravity bulbs, hey if your worried about the environment we'll even invent energy saving ones.



More insane ramblings by the people who brought you beeeer milkshakes!
No one can see their reflection in running water. It is only in still water that we can see.

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Wednesday, February 21, 2007 1:26 PM

DROSTIE


Quote:

I have one question, though. Where did you get the idea that the main engine was some sort of nuclear explosion? I don't recall that being suggested in any of the canon or even in the RPG. Is it just something you assumed based on its appearance?


Well, it's a little of both. It's mostly a description of how the main thrust seems to work. Now, I'm not sure if it counts as "canon" (I've never bothered with the various fanboy classification schemes), but it was best expressed on the special feature clips on the Firefly DVD.

More specifically, one of the segments is called "Serenity: The 10th Character." In there, the visual effects supervisor, Loni Peristere, said, "One of the things we sort of latched on to for the interplanetary travel was this idea of a big fusion explosion behind the backside of the spaceship, that would propel it inordinately faster than anything that we have on the Earth."

So it's not an original description, but it's probably not canonical either. It's ultimately just an observation on how the drive appears to work.

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Wednesday, February 21, 2007 1:48 PM

WHODIED


Er.. gravity is the wit of Sol?

--WhoDied
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