CT LBB 2 1977 did not mention TL, however CT LBB 3 1977 has a Technology Chart that can be used.

CT LBB 2 1977,1981 mentions TL for computers only and CT LBB 3 1977, 1981 has another Technology Chart.

CT LBB 5 HG did away with the charts of CT LBB 2 and in theory was used to update the ships built using CT LBB 2 that limited standard hulls to 5,000 tons.

Phil Pugliese mentioned the Gazelle which is a 300 ton hull with a J5 drive. The J5 drive on a 300 ton requires 150 tons of fuel to make one five parsed jump. The jump fuel of 150 tons can not be stored internally so a compromise was made of storing 60 tons for a two parsec jump internally and using drop tanks with additional fuel. Using drop tanks carrying 90 tons fuel does not allow a four parsed jump, but 100 tons of fuel allows the J5 drive designed for a 300 ton hull allow a 400 ton hull to make a four parsec jump.

In JTAS 24 1985, thank you Timothy for the bibliographies, Mark Miller wrote an article about Jumpspace which makes me think that the jump grid is designed to balance a specific amount of energy for the maximum jump rating of the installed drive. A 400 ton hull with drop tanks has its jump drive grid calibrated for one four parsec jump using all the fuel available. Jettisoning the tanks does not change the four parsec calibration. A 300 ton hull with a J5 drive has it jump drive grid calibrated for one five parsec drive. By adding and retaining 100 tons of fuel in drop tanks increases the hull to 400 tons with a jump drive grid calibrated for jump 5 at maximum charge the J5 drive can move the 400 ton hull four parsecs.

Anyway, the above is how I understand the material which was reinforced by the GM and players I was with in the late 70s and early 80.

Thank you for the reply.

Looking at the LBB gives an interesting perspective, since the “standard” drives in there don’t have a TL limit on potential (just a cap of J6), but do have one on drive size. This means that you can take the highest potential JN and multiply it by that hull size/100 to create a “real potential range” number for that particular drive model (or just divide tonnage by 100 and multiply by jump number if you’re doing this for individual ships), and then divide that by the actual hull size you’re installing the drive in to get that configurations jump number.

You can also do this for M-drives, to get tons of thrust for a drive model.

High Guard introduced “Jump potential by TL”, but it sort of implies, in the context of HG vs LBB2, that this applies only to custom military jump drives.

Looking at Tom’s example, j4 for 400 tons would be potential 16, and when installed in a 300 ton hull would give J5.33.

On Sun, Oct 6, 2019 at 11:49 Phil Pugliese (via tml list) < xxxxxx@simplelists.com> wrote:

As I recall, in the original trio of LBB's, you selected a jump drive by letter (A,B, etc) from a table that was cross-ref'd with hull sizes to yield a jump value.

Sometimes a change in hull displacement would NOT change the jump value but usually it did.

In the CT HG lbb, the 'tonnage' of the JD was calculated as a % of the hull size modified by the max J desired, so if the ship's displacement was modified (re: Gazelle CE or in the case of retaining external demountable tanks) then J was also altered. (NOTE: *internal* demountable tanks does NOT change J MAX)

I would say then that the answer is 'Yes'.

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On Sunday, October 6, 2019, 11:15:01 AM MST, Thomas RUX < xxxxxx@comcast.net> wrote:

Hello all,

Back in when I picked up Traveller my impression, which was reinforced by the GM, has been that a J4 drive has a maximum range of four parsecs regardless of the hull size that it is installed in.

Can a J4 drive built for a 400 ton hull allow a 300 ton hull to make a five parsec jump?

Tom Rux

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