Yet more High Speed Projectiles

> From: [email removed]
> Subject: (2709) Yet more High Speed Projectiles
>
> Houston, we have a problem...

  Ok, I admit that using real physics on an SF RPG is a rather dirty trick:)

> If Bertil is correct in his calculations (No I'm not going to double check)

  I did one error, but it has only minor effect on the results.

> If you look at it from a total energy avaliable perspective, I would question
> the basis of the equations you use for available energy.  If you base it upon
> the megatraveller power plant output, then you are questioning the very basis
> of the power plants.  But remember, the power plants were designed (by GDW)
> to account for the performance of non existant forms of locomotion.

  A scoutship weighs about 1350 tons, Ignoring relativistic effects (which I
suspect are of marginal effect at 0.1c, and in any case they will just make it
*harder* to reach 0.1c), it's kinetic energy at 0.1c is mv^2/2:

  1.35e6 * 3e7^2 / 2 = 6.075e20 Joules.

  The total energy contained in the mass of the ship is mc^2:

  1.35e6 * 3e8^2 = 1.215e23 Joules.

  So the energy equals 1/200th of the ships total mass. (Not 1/14th as I said,
but that's what happens when I play physicist, stupid me <kick!> <ouch!> :)

  1/200th of the ships mass is 6.75 tons, ie about 100kl of hydrogen, but
fusion gives far less energy than total mass->energy conversion so it is still
unlikely that the fuel will contain enough energy.

  (Yes, ok, the calculations contain errors, the relativistic effects for one
thing, and the ship will become lighter as it uses fuel, thereby requiring less
energy, but I think these effects are minor.)

> But, I might point out that in order for traveller engines to work, we must
> accept the fact that
> 1	The scout ship has 2G capable engines.
> 2	The fuel volume is capable of lasting 30 days.

  There is one way out of this dilemma, and that is to assume that the engines
are *not* reactionless but that they have exhaust and that exhaust has a certain
speed. Their acceleration will (If I understand it correctly) decrease as the
ship comes closer to that speed.
  That way the ship will still mostly have a 2G acceleration in it's typical
envelope (planet to 100diameters, in-system transfers etc) but if someone
tries to take it outside that envelope by for example going full tilt for
more than a week, the acceleration will decrease.

  This will unfortunately mean that all calculations of acceleration, range and
time will become very complex....

> If as you suggest a ship has only 1/14th the required energy to reach .1c
> then the ship should only be able to accelerate at 2/14 G's (1/7 G) and
> so the scout chip can not perform as it is required to perform.

  Every time you double the speed, the energy required quadruples. So it is
quite possible to have a ship that can do 2G in a low speed interval but can't
do more than 1/200th G in a higher speed interval.

> Ah well, It seems to me it just comes down to what brand of metaphysics
> you prefer.  How many ancients can dance on the head of a pin?

  That depends on if the pin is made of monadium, and on how many ancients
there are left that are able to dance, and on if the coyns say that dancing is
a good idea:)

> Mr. Scott

- - -bertil-
- - --
"Med ett sjyst ja"rnro"r sla^r man va"rlden med ha"pnad!"

> Date: Thu, 1 Aug 1991 18:48 CDT
> From: [email removed]
> Subject: (2709) Yet more High Speed Projectiles
>
> If
> Bertil is correct in his calculations (No I'm not going to double check)
> It is impossible for the scout to reach .1c.  Insufficient total energy.
>
> But, I might point out that in order for traveller engines to work, we must
> accept the fact that
> 1	The scout ship has 2G capable engines.
> 2	The fuel volume is capable of lasting 30 days.
>
> These are the underlying assumptions of all traveler designs.  The number of
> Megawatts of power input is a guesswork based on metaphysics.  If your
> argument is based on that fact then we are arguing about metaphysics.

Just for the record, the argument is between classical physics and the
modifications of relativity as identified by Einstein and Lorenz.  This is
not metaphysics (which deals with philosophy.)

> My point is that starship engines are based upon the fact that they are
> supposed to be capable of boosting a ship at accelerations from 1G to 6G
> 10 to 60 meters per second for a period of thirty days.
>
> If you accept that fact, then .1c is in.
>
> If you look at it from a total energy avaliable perspective, I would question
> the basis of the equations you use for available energy.  If you base it upon
> the megatraveller power plant output, then you are questioning the very basis
> of the power plants.  But remember, the power plants were designed (by GDW)
> to account for the performance of non existant forms of locomotion.
>
> If as you suggest a ship has only 1/14th the required energy to reach .1c
> then the ship should only be able to accelerate at 2/14 G's (1/7 G) and
> so the scout chip can not perform as it is required to perform.

The real issue is one of game balance.  The game was designed to be able to
role play in the future.  The game was not intended to require the players
and referee to calculate the intricacies of relativistic flight.

The purpose behind the drives was not necessarily to develop large mass
driver weapons and planetary destruction.  They were made to move a
ship from point "A" to point "B" and have the crew do something interesting
at point "B" (other than die in a large ball of fire.)

If a player wanted to play with these types of speeds, I would make him do the
calcs and figure out the fuel requirements and drive requirements.  This type
of play being outside the bounds of the game design to begin with.

Also, just for the record, if the speeds are less than about .1c, the effects
of relativity can be neglected in general.  Mass increase is about half a
percent at this speed.

- - --
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| *-=Carl=-*  INTERNET - [email removed] | Time is nature's way to keep |
|             DELPHI - WULFGAR                | everything from happening    |
| Carl Fago   Portland, OR                    | all at once.    -anon.       |
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