Mongoose Reactio M-Drive cost

[TheOtherDude]

Hi,

in High Guard, the Reaction Drive ist introduced.

"The reaction drive takes the same space as a gravitic drive, and costs less,[...]"

I am now desperately trying to find out, how much less it costs, but either I am blind, or the info is missing. There is a table with Reaction M-Drive cost for small craft, but nor for ships.

I also tried to calculate the cost for ship reaction m-drives according to the small craft table, but the factor in the small craft table is not linear.

Can anybody point me to the relevant chart where I can find the point cost ship reaction m-drives?

Thank you very much.

Kind Regards

TheOtherDude

 

[atpollard]

I'm pretty sure that the answer is no.
The correction isn't in the errata either.

Looking at the Archaic Shuttle (in MgT High Guard) isn't much help either. The 12 Mcr sL (grav) drive costs MCr 5.5 as an sL (rocket) drive.

Avenger published a good 'Traveller: Archaic Small Craft' PDF that suggests that a reaction drive costs and weighs half of a comparable Grav drive.

 

[steventirey1985]

The Small Drive Costs and Tonnage chart on page 58 gives the size and costs for small craft drives. I can't find a formula that fits for the sizes, but the costs are 2x the reaction drives tonnage. But the chart also shows the reaction drives being smaller than the gravitic drive, while the description of the reaction drive you quoted says that they should be the same.

But if you assume that small craft use different rules (like they do in other areas, like weapons), then that is fine. Starship reaction drives could be the same size as gravitic drives, and cost MCr 2 per ton of drive. That would make reaction drives for 100 to 2000 ton ships slightly cheaper (only MCr 2, so not a whole lot). Capital ship (3000 tons +) gravitic drives only cost MCr0.5 per ton, so maybe reaction drives for capital ships should cost MCr0.25 per ton. That is probably what I would do.

 

[TheOtherDude]

Thank you for your answers. Always good to know that I am not blind

I just dropped Mongoose a line, I will post their answer here.

 

[TheOtherDude]

Hi,

the answer from Mongoose is, that reaction drives are only meant for small craft, the reaction drive technology is not powerful enough to move larger vessels.

I think the entry in the star ship options and the small craft options in High Guard does imply that they are not only meant for small craft, but well...

My designated brother-in-law knows the excel-fu and helped me to get a function out of the small craft table which turns out to be:

tonnage = 0,522 x G-DriveTonnage ^ 0,903
cost = 0,571 x G-DriveCost ^ 0,892

If you apply this to the small craft g-drive values you do not get exact matches, but these formulas give the closest he could come up with.

Using these formulaes on the G-Drive table gives awkward decimal places, bt with some rounding this should provide a usable table.

I hope these formulaes will help someone else as well.

Cheers

TheOtherDude

 

[bubbacleese]

Being on this (west) side of "The Pond" please confirm this translations of your formula:

tonnage = 0,522 x G-DriveTonnage ^ 0,903
cost = 0,571 x G-DriveCost ^ 0,892

tonnage = 0.522 "multiplied by" G-DriveTonnage "divided by" 0.903

 

[fusor]

the answer from Mongoose is, that reaction drives are only meant for small craft, the reaction drive technology is not powerful enough to move larger vessels.

It's absolute nonsense for anyone to claim that "reaction drives are not powerful enough to move larger vessels".

Reaction drives can move anything, regardless of mass. Granted, it's harder to move a more massive object than a less massive one given the same amount of energy, so what they may mean is that it's harder to make a reaction drive practical for very large objects (given that they'd require more powerful thrusters, more fuel, etc).

In space at least, the smallest kick (whether from a reaction drive or a hypothetical reactionless one) can "move" a million-ton spacecraft. It won't change its vector by much at all, but it will still change it.

 

[atpollard]

Being on this (west) side of "The Pond" please confirm this translations of your formula:

tonnage = 0.522 "multiplied by" G-DriveTonnage "divided by" 0.903

tonnage = 0.522 "multiplied by the quantity" [G-DriveTonnage "raised to the power of" 0.903]

It is a formula for a curve.

 

[TheOtherDude]

tonnage = 0.522 "multiplied by the quantity" [G-DriveTonnage "raised to the power of" 0.903]

It is a formula for a curve.

Yes, that is right.

Sorry, I did not know that there are differences in the way mathematic formulaes are expressed on the two sides of the pond. What would be your notation?

 

[atpollard]

Yes, that is right.

Sorry, I did not know that there are differences in the way mathematic formulaes are expressed on the two sides of the pond. What would be your notation?

As far as I know, only the coma and period swaping function.
(US) 4,513.27 = (EU) 4.513,27

"^" is from spreadsheets and computer programming since most text applications don't handle superscripts well.

 

[Icosahedron]

As far as I know, only the coma and period swaping function.
(US) 4,513.27 = (EU) 4.513,27

"^" is from spreadsheets and computer programming since most text applications don't handle superscripts well.

Just FYI, UK is 4,513.27 too.