Vehicle Displacement in Starship designs

[D. Foxx]

Looking for a little clarification here. While designing a starship, I was setting aside space for a couple of vehicles and came into this little disconnect...I couldn't find the dTons for an air/raft and an offroad type vehicle in the main MGT rulebook. (I did find a table later, after I found this disconnect)

Trying to be clever I went to the scout ship and saw that the air/raft was rated at 4 dTons. Not one to quit, I turned to the Supp 5 and 6 to see if there was any more details for an off road vehicle of some type. I found a suitable one, but dTons wasn't listed hower M cubed (M3) was. Both Supp 5 and 6 state "calculate displacement as 1 dTon for every 10 M3". Wanting to verify this, I crosschecked the air/raft and found that it is listed as 8 M3 or less then 1 dTon in Supp 5.

So what takes precedent; 4 dTons for the air/raft based on what is in the MGT rule book on the Scout Ship design sheet (pg 115) or the rules and stats in Supp 5 (rule on pg 4, stats on pg 54)? And just to muddy this up a little more, I did just find a table on pg 111 of the rulebook that also contradicts Supp 5 but supports the scout design sheet.

 

[far-trader]

Really?! 10m3 per dton!? Is that an indication that the author(s) find math hard and had to round to even 10s? Or they presume the Traveller consumer finds math so hard they have to simplify it to even 10s?

:file_28:

Traveller dtons have always been 13.5m3 or 14m3, except in GT which is non-metric and does do some minor rounding (like iirc 1G being 10m/s/s instead of 9.8m/s/s). The math there really isn't hard: A dton is 1.5m x 3.0m x 3.0m = 13.5m3. In TNE a dton was 2.0m x 2.0m x 3.5m = 14m3. I wonder how they get 10m3?

As to the gross discrepancy between the two ideas for the Air/Raft all I'll say is the Air/Raft has long been one messed up bit of technology

Given the... differences, and lack of data you've found, I guess you could always pick what you like, seems as if that's what some are doing for publication

Not a lot of help I guess, but I was just shocked by the information.

 

[aramis]

Really?! 10m3 per dton!? Is that an indication that the author(s) find math hard and had to round to even 10s? Or they presume the Traveller consumer finds math so hard they have to simplify it to even 10s?

All that does is include the 40% overage for hangared vehicles. (It was 30% in other editions.)

 

[robject]

So what takes precedent; 4 dTons for the air/raft based on what is in the MGT rule book on the Scout Ship design sheet (pg 115) or the rules and stats in Supp 5 (rule on pg 4, stats on pg 54)? And just to muddy this up a little more, I did just find a table on pg 111 of the rulebook that also contradicts Supp 5 but supports the scout design sheet.

4t is traditional, if that counts for anything.

 

[atpollard]

Really?! 10m3 per dton!? ... I wonder how they get 10m3?

Easy there big guy. I disagree with the Mongoose vehicle dTon rule because it is too non-intuative, but it is not the work of an idiot.

The Internal volume of a vehicle is 2 dTons per 27 cubic meters (13.5 cubic meters per dTon for someone who hates decimals). If you want to know the External volume, like how many air-rafts can be packed into a 100 dTon hold, then each 10 cubic meters of internal volume is 1 dTon of External volume (with the side view mirrors still intact).

So what does this mean in actual use, well a truck with 135 cubic meters of internal volume would hold 135 x 2/27 = 10 dTons worth of stuff, but require 135 / 10 = 13.5 dTons worth of cargo space to transport.

Note that using the old +30% rule of thumb for hangars, a 10 dTon craft would require 13 dTons of hangar space. 13 dT vs 13.5 is pretty close, so 1 dTon per 10 cubic meters sort of works.

 

[Icosahedron]

Or they presume the Traveller consumer finds math so hard they have to simplify it to even 10s?

The math there really isn't hard: A dton is 1.5m x 1.5m x 3.0m = 13.5m3.

You sure about that, FT? o:

I haven't read deeply into Mongoose sizing, but the Air Raft is traditionally 4dT and internal/external volume is a traditional problem. Rounding to 10dT both internally and externally doesn't solve that problem.

 

[far-trader]

I was just replying to the posted information I appreciate the expansion and explanation of the details

You sure about that, FT? o:

Heh, good catch Not a maths issue at least, just a brain fart (I wasn't even doing the math or I would have caught it)

Anyway, the explanations clear things up a bit. I still don't get the reported 8m3 Air/Raft though. If anything, using the logic(?) of the authors shouldn't it have been designed at 40m3 to be the stated 4tons of required space?

It still sounds like a silly way to attempt to achieve the desired result to me. And I agree with Icosahedron it doesn't really fix the whole issue. I suppose the best I could say about it is at least they tried?

 

[atpollard]

Trying to be clever I went to the scout ship and saw that the air/raft was rated at 4 dTons.

Both Supp 5 and 6 state "calculate displacement as 1 dTon for every 10 M3". Wanting to verify this, I cross-checked the air/raft and found that it is listed as 8 M3 or less then 1 dTon in Supp 5.

So what takes precedent; 4 dTons for the air/raft based on what is in the MGT rule book on the Scout Ship design sheet (pg 115) or the rules and stats in Supp 5 (rule on pg 4, stats on pg 54)? And just to muddy this up a little more, I did just find a table on pg 111 of the rulebook that also contradicts Supp 5 but supports the scout design sheet.

Internal consistency between books has, thus far, seemed to elude Mongoose Traveller, but the air/raft-size problem is actually an old one.

An air/raft has always been listed as (about) 4 dTons, which is the size of a very large (7.5 m/24 ft long) delivery truck or 47 seat school bus, but the text description and pictures have always been closer to a small pickup truck (the bounding box - L x W x H - for a regular pickup is about 1.6 dTons) or WW2 jeep (the bounding box for a WW2 Jeep is about 0.7 dTons) in size.

An air/raft at 8 cubic meters is very close in size to the WW2 jeep and, in my opinion, closer to what the size of an air/raft should be than a 47 passenger school bus.

 

[Icosahedron]

A typical lock-up garage is about 2dT, so most 'domestic' vehicles won't exceed that. One explanation I've used is that the 4dT doesn't refer to the air raft itself, but to the 'garage workshop' that it's usually parked in. Like a double garage, this not only holds the vehicle, but allows enough space around it to carry out comprehensive repairs and maintenance during those boring Jumps. Not a perfect explanation, perhaps, but it's as good as any other.

 

[D. Foxx]

Thanks for all the input. Pretty much gonna use Supp 5 for the vehicle displacement and I'll handle hangar/garrage space as a designers choice.