Enforcing Newton's second law.

[daniel_t]

I know, I know. Complaining about the breaking of some particular, currently understood, scientific principle is kind of silly when so many of them are broken in just about any Traveller universe, but I have a real problem with the haphazard breaking of Newton's second law. Specifically, artificial gravity and reactionless thrusters.

The biggest problem with enforcing Newton's second law would probably be that I’d have to redesign every ship published...

Your thoughts?

 

[robject]

I know, I know. Complaining about the breaking of some particular, currently understood, scientific principle is kind of silly when so many of them are broken in just about any Traveller universe, but I have a real problem with the haphazard breaking of Newton's second law. Specifically, artificial gravity and reactionless thrusters.

The biggest problem with enforcing Newton's second law would probably be that I’d have to redesign every ship published...

Your thoughts?

AD2300?

Or:

Assume all acceleration is at appx 1G and orthogonal to the deck plans.

Re acceleration compensation (3Gs and above is insane, and 2G is uncomfortable): Change the definition of the maneuver drive rating to be an abstract "Agility" rating, used as a measure of combat responsiveness?

 

[the angle]

Those high accelerations are unsustainable only over long periods, as in in-system travel between planets. In combat, 3-6g maneuvers wouldn't be a problem for humans, especially if you were outfitted with a compensating suit and lying in an acceleration couch. Even the space shuttle hits 3gs during launch.

Steve

 

[atpollard]

The alternative to 'reactionless' thrusters are either:

1. large slow ships filled with 90% fuel able to travel to the gas giant in weeks or months.

2. large fast ships filled with 90% fuel whose exhaust qualifies as a spinal mount weapon.

As mentioned earlier, artificial gravity can be handwaved away by simply accelerating the ship "up" at 1 G.
Reaction drives are harder to make work without completely altering Traveller into something else (like 2300)
or shattering thermodynamics and conservation of energy rather than conservation of momentum.

 

[daniel_t]

AD2300 did away with maneuver drives completely. I don't want to go that far. (And anyway, what happens to the ship's momentum when the Stutterwarp is shut down?)

General acceleration would be at about 1G and orthogonal to the deck plans which is why I would have to redesign the ships. Maneuver drive thrusters have to be under the ship instead of in the back. Also, a 1G Maneuver drive would not be able to lift off a world with 1G gravity.

Lastly, the US Space Shuttle subjects its occupants to 3G acceleration during launch and fighter pilots are often subjected to up to 6G. I don't think that it's too much of a problem during battle.

 

[robject]

The thing about Newtonian mechanics is, indeed, that you only have two launch vehicles: the rocket and the airplane. So, if you wanted, you could see ships which have launch boosters -- either integral or rented, ejectable rockets -- and either launch upright (the Type C) or fly into orbit (the Type S). Flyers only need 1G, but it takes longer to get to orbit. Rockets, as you noted, need more Gs for a shorter period of time.

Redesigning most ships is no big deal: assume the rear unit is only for launch, and that the actual, space-operation M-drive proper needs no exhaust port. It's just part of "the hull" or something.

Finally, for battles, make sure your combat times are short enough so that 6G's can be tolerated. Don't use CT's multi-hour-long combat sessions.

 

[mike wightman]

Also, a 1G Maneuver drive would not be able to lift off a world with 1G gravity.

Aaaarrrrgggghhhh.

For the last time can we put this physics question to rest.

How many planes today actually are capable of generating 1g of thrust? Not many.

How many fly? Lots.

There is more to getting to orbit that thrust.

If you are generating 1g of constant acceleration you eventually reach the speed of light, let alone escape velocity. That's the true magic of Traveller m-drives. Realistic? Not on your nelly

 

[rancke]

If you are generating 1g of constant acceleration you eventually reach the speed of light, let alone escape velocity. That's the true magic of Traveller m-drives. Realistic? Not on your nelly

Well, you never reach the speed of light, although you'll get closer and closer.

Actually, I've been idly pondering a starsdrive that simply ignored Einstein and just kept on accelerating at 1G until midpoint (i.e., ignoring relativity), then decellerating for the rest of the trip. I wonder what the ramifications would be, in terms of the time it'd take to travel around in Charted Space. One day I'll sit down and calculate a few trips.


Hans

 

[Max]

Well there's always FF&S 1 (TNE) which has rules for other drives or T4 (game book or FF&S 2) which has some useful HePlaR drive rules for those who find the reactionless drive too unrealistic. Both also have rules for acceleration effects on people without artificial gravity and FF&S 1 has a (short) section on pseudo-gravity created by spin. Conversion to either is possible (T4 is easier, works quite well with the other Ship Design Systems and the tables/fuel rules are part of the BITS archive ) but the ships would are less space efficient, add the fuel for a multi-G HePlaR drive to the jump fuel and you can easily eat up 90% of the ship volume in no time.

 

[aramis]

Well, you never reach the speed of light, although you'll get closer and closer.

Actually, I've been idly pondering a starsdrive that simply ignored Einstein and just kept on accelerating at 1G until midpoint (i.e., ignoring relativity), then decellerating for the rest of the trip. I wonder what the ramifications would be, in terms of the time it'd take to travel around in Charted Space. One day I'll sit down and calculate a few trips.


Hans

712 days at 1G for 1PC; 291 for 6G

 

[mike wightman]

Well, you never reach the speed of light, although you'll get closer and closer.

Actually, I've been idly pondering a starsdrive that simply ignored Einstein and just kept on accelerating at 1G until midpoint (i.e., ignoring relativity), then decellerating for the rest of the trip. I wonder what the ramifications would be, in terms of the time it'd take to travel around in Charted Space. One day I'll sit down and calculate a few trips.


Hans

That's actually a very nice idea - why have I never thought of it before?

Nice one Hans

 

[mike wightman]

712 days at 1G for 1PC; 291 for 6G

And is that for constant acceleration to mid point then deceleration?

What if you had something like the Lensman inertialess drive so that you could accelerate all the way then just stop?

(Too lazy to do the math )

 

[rancke]

712 days at 1G for 1PC; 291 for 6G

Thanks, Wil. I guess I'll drop that idea.


Hans

 

[robject]

And is that for constant acceleration to mid point then deceleration?

What if you had something like the Lensman inertialess drive so that you could accelerate all the way then just stop?

(Too lazy to do the math )

http://eaglestone.pocketempires.com/scripts/vilanitools.html

Calculate for twice the distance, then halve the time

 

[atpollard]

Thanks, Wil. I guess I'll drop that idea.


Hans

Or use the faster than 6G drives from MgT.
(Or extend the table in CT HG.)

 

[aramis]

And is that for constant acceleration to mid point then deceleration?

yes
T=2(D/A)²...

 

[veltyen]

Actually, I've been idly pondering a starsdrive that simply ignored Einstein and just kept on accelerating at 1G until midpoint (i.e., ignoring relativity), then decellerating for the rest of the trip. I wonder what the ramifications would be, in terms of the time it'd take to travel around in Charted Space. One day I'll sit down and calculate a few trips.
Hans

From on board the vessel that should be pretty much what appears to happen.

Frame dragging causes the time on the vessel to become slower and slower - as you reach the limit of infinite velocity (from the perspective of someone on the vessel) exceedingly long trips appear to take almost no time.

The only problem is from an outside perspective. So while it might only feel like a couple of years to cross hundreds of light years (from the inside) it has taken thousands of years from an outside perspective. The limit of the speed of light only happens if you feel the need to retain "community".

 

[the angle]

In the type of universe being postulated, "ships" as such probably would never land on planets, so the question of landing/liftoff thrust is moot. They would park in high orbit, and transit to and from the surface would be by shuttle, space elevator, or some other mechanism. Think 2001: A Space Odyssey here.

Steve

 

[boomslang]

I know, I know. Complaining about the breaking of some particular, currently understood, scientific principle is kind of silly when so many of them are broken in just about any Traveller universe, but I have a real problem with the haphazard breaking of Newton's second law. Specifically, artificial gravity and reactionless thrusters.

It's not really that haphazard if you postulate some sort of field-effect principles similar to magnetism.

Magnets can move objects without reaction mass by first storing the energy in a field -- the energy is then removed from the field and converted into kinetic energy at a distance.

A similar mechanism may be proposed for gravitics (and even jump drive, which IMTU is a further development of the principle): the m-drive (or grav plate repulsor -- I put them in the ceiling IMTU since repulsors precede tractors by several TLs) stores energy in a field around the device and the vehicle it is mounted in, and this field can then push against the mass of the rest of the universe (or a crew member walking down a corridor) to translate itself relative to that object. Likewise, within this field, objects only see the mass of other objects within the field (similar to how the inner wire of a coaxial cable sees only the current in the surrounding wire and pretty much ignores the entire rest of the universe outside it), which in inertial terms means such objects remain at rest within the little pocket universe of mass they inhabit.

Thus it all goes away, based on extending principles from EM fields into gravitic ones; inertia, reactionless thrust, and (again, IMTU at least) even FTL travel become possible all because the effects of gravity may be isolated from the outside universe and localized by one handwaved mechanism that is simply an extension of known physical principles of EM imported to the (hypothetically unified) theory of gravity...

There is, of course, a non-trivial energy and waste heat cost for such machinery: even if there is a workaround for Newton, thermodynamics will not yield... but that's part of what keeps Trav "hard" SF.