Re: Crystal Based Propulsions

In <URL:news:local.spelljam> on Fri 27 Oct, Ariel Sibal wrote:
> Acoustical Based Crystal Propulsion
> 
> The crystal is a five feet long and six inches in
> diameter shard. The crystal is stationed at the rear
> of the craft. The crystal is held suspended horizontal
> by cables, blocks and tackles. About six inches of the
> crystal is sticking out the back of the craft. A
> dwarven stone harper can strike the crystal and make
> it vibrate. The stone harper can control the pitch and
> wave of the vibrations by striking, manipulating and
> laying hands on the crystal. As the vibration grows
> stronger it creates sound waves that exit at the end
> away from the stone harper. The waves propel the craft
> forward. This type of propulsion can be used on light
> crafts. The length (in feet) times the width (in feet)
> divide by the tonnage of the craft gives the SR. The
> ship can be steered using sails or rudder.

Does the harper need a certain minimum amount of skill?  Maybe
based on the maximum SR and the maximum tonnage?  Does the
crystal somehow suck their energy, so they tire like a
spelljamming helmsman?

What is the maximum tonnage that can be used?  Maybe equal to the
length of the crystal in feet, i.e. 5 tons for your 5' example? 
Possibly doubling the maximum tonnage to 10 tons for a 5' crystal
would be a good idea?

And doubling the SR gained from crystal size, or only 1 ton craft
would have more than SR 1, and I think this feels like something
people wouldn't fit to a 1 ton craft.

Specifying what the crystal's saving throw if would be useful,
and whether there is a chance of cutting-down a broken one to get
some use out of it.

Does this works other than in wildspace, and can it be used to
take off from any body larger than size class A?

Might I suggest an Arcane Price of 10,000 gp per crystal width
times length, so your example would cost 25,000 gp.


> Thermal Based Crystal Propulsion
> 
> A large crystal shard is embedded along the length of
> the craft. The crystal is heated by using mirrors,
> magnifying glass or other means to direct sunlight to
> the crystal. The heat builds up and released at the
> end of the crystal away from the end being heated up.
> An SR of 4 can be achieved when near the sun. SR drops
> by one half for every planetary orbit away from the
> sun. The ship crew can enhance the effective SR if
> they are familiar with the propulsion system. The ship
> can be steered using sails and rudder.

Might I suggest that the SR drops by a half SR for every quarter
AU away from the sun, so at the distance Earth is from the sun
you get SR 2.  So, at the orbit of Mars, about 1.5 AU from the
sun, you are down to SR 1, and the Helm isn't usable more than 2
AU from the sun, i.e. you can't quite get to the asteroid belt.

Generous GMs might say the Helm cuts out automatically 2AU from
the sun, and you can squeeze SR 0.1 out of it, enough for you to
get close enough to the sun to get SR 1 and spelljamming speed
with a few hours flight.

Otherwise this Helm will respond in some very strange ways in
systems with strange planetary orbits - what would it do in
systems with no planets, just lots of asteroids, for example?

(Unless I have misunderstood you, and by 'planetary orbit' you
mean 1 AU, or something?)

Worth noting that this assumes a sun a bright and as hot as
Earth's - dimmer suns make this far less useful.

I'd assume this stops working if you get something, like a moon
or planet, between you and the sun.  I further assume that this
only works in wildspace, and can't be used to take off from any
body larger than size class A.

Specifying what the crystal's saving throw if would be useful,
and whether there is a chance of cutting-down a broken one to get
some use out of it.

I'd like to know what the tonnage limit is on this - I'm guessing
five tons to twenty tons based on crystal size.

Might I suggest an Arcane Price of 1,000 gp per maximum tonnage,
so they will be 5,000 gp to 25,000 gp, maybe in steps of 5 tons.

-- 
Dreamer
dreamer@??????.?????.??.uk
http://www.romsys.demon.co.uk/