A while back, I mulled over the curiosity of Traveller's starship drop tanks and wondered why we don’t see more of them. Some of the feedback I received was that drop tanks “break the game.”
I wasn’t sure what that meant, so I dug into it.
Some history
My original post looked at the curiosity of drop tanks and wondered why we didn’t see more of them. As far as I can see, only the Gazelle Close Escort has ever had drop tanks. (It’s the only ship in Mongoose’s Core Rules and High Guard – I’ve not checked every supplement!)
Drop tanks appeared in the Traveller universe in High Guard (1979 and 1980) and with the Gazelle Close Escort in JTAS 4 (1980) and Traders and Gunboats (1980).
The Gazelle has been canon ever since.
But drop tanks have never reappeared – and the latest iterations of Traveller give them a harsh penalty (a high probability of being destroyed when entering jump) which rules them out of use.
Or does it?
Faaaaaar Trader
Let’s build a Free Trader with a jump-6 drive. We’ll replace the J1 drive and its fuel (30 tons total) for a drop tank mount and a J6 drive (40 tons total). So we lose 10 tons of cargo space, reducing us to 71 tons.
For the sake of this argument, I will ignore many of the ship costs – mortgage, maintenance, berthing, salaries and other running costs. I’m looking at the cost of fuel, the drop tanks themselves, and income from freight and passengers.
Costs
Jump costs have a linear relationship. The costs for J6 are six times that for J1.
| Jump | Fuel needed | Fuel cost (Cr500 refined) | Drop tank cost | Average drop tank cost per jump | Total costs |
|---|---|---|---|---|---|
| 1 | 20 | Cr 10k |
Cr 500k | Cr 375k | Cr 385k |
| 2 | 40 | Cr 20k | Cr 1,000k | Cr 750k | Cr 770k |
| 3 | 60 | Cr 30k | Cr 1,500k | Cr 1,125k | Cr 1,155k |
| 4 | 80 | Cr 40k | Cr 2,000k | Cr 1,500k | Cr 1,540k |
| 5 | 100 | Cr 50k | Cr 2,500k | Cr 1,875k | Cr 1,925k |
| 6 | 120 | Cr 60k | Cr 3,500k | Cr 2,250k | Cr 2,310k |
The cost of the drop tank itself dwarfs the fuel cost.
(Drop tanks are destroyed about 60% of the time they are used, we shouldn’t pay the full rate – let’s say 75% to allow for recovery costs. That’s my “average drop tank cost per jump” column. I’m not sure when this constraint appeared – it’s not in the little black books.)
Income
Income, however, is not linear.
| Jump | Freight | Low passage | Medium passage | High passage | Total income |
|---|---|---|---|---|---|
| 1 | Cr 1,000 | Cr 700 |
Cr 6,500 | Cr 9,000 | Cr 122,500 |
| 2 | Cr 1,600 | Cr 1,300 | Cr 10k | Cr 14,000 | Cr 197,600 |
| 3 | Cr 2,600 | Cr 2,200 | Cr 14k | Cr 21,000 | Cr 312,600 |
| 4 | Cr 4,400 | Cr 3,900 | Cr 23k | Cr 34,000 | Cr 527,400 |
| 5 | Cr 8,500 | Cr 7,200 | Cr 40k | Cr 60,000 | Cr 987.5k |
| 6 | Cr 32k | Cr 27k | Cr 130k | Cr 210k | Cr 3,622k |
I’m basing total income on 71 tons of freight, and 20 low, three medium and two high passages.
As you can see, there’s a huge leap in income between jumps 5 and 6.
Profits
So what does all this mean?
| Jump | Profit |
|---|---|
| 1 | Cr -262,500 |
| 2 | Cr -572,400 |
| 3 | Cr -842,400 |
| 4 | Cr -1,012,600 |
| 5 | Cr -937,500 |
| 6 | Cr 1,312,000 |
So jumps 1-5 lose you money – but if you can find a reliable J6 route, you can make it big and earn Mcr 2.6 every single month! (This is why I didn’t worry about the other costs; they’re peanuts compared to the profit you’ll make running a J6 ship.)
And that’s why drop tanks “break” Traveller. (Although “break” is a loaded term. All that would really happen is that competition would ensure the J6 prices drop.)
Are jump drives a mistake?
This makes me think that drop tanks were a mistake.
Maybe they were fine as an idea in 1980 Traveller (but starship economics were different back then). However, drop tanks do weird things to Mongoose's 2nd Edition Traveller economics. So if they aren’t destroyed during a jump (causing a significant financial loss), then everyone freely zips around the Traveller universe.
And the poor old Gazelle?
On the scale of things, it’s not a big ship – only 300 tons. It’s dwarfed by capital ships, and I find it hard to believe that the costs of fitting drop tanks (at two million credits each) to get an extra two parsecs range would survive first contact with a cost-benefit analysis. (But I’ve not done that analysis, so maybe I’m wrong.)
Maybe drop tanks should have been retconned and the Gazelle redesigned accordingly. That’s what I would have done.
Edit: Updated to correct the first appearance of drop tanks. As far as I can tell, they first appeared in High Guard (1979) with the Gazelle appearing in Traders and Gunboats and JTAS 4 the following year.
Drop tanks weren't really a mistake in Classic Traveller where the prices for passage and freight were the same per jump regardless of distance. The problem back then was with the Gazelle's design - it should only have had three hardpoints for weapons rather than the four it was given.
ReplyDeleteWhere it does break the system for trade is in editions where freight/passenger prices increase with jump distance; I believe that only occurs in the GURPS and Mongoose editions, with MgT2e being the most extreme.
Thanks for the reply. Yes, I'm only considering Mongoose 2nd Edition Traveller - while I do own some earlier editions, I don't fancy trying to reconcile all the differences.
ReplyDeleteBut having said that, I didn't realise starship economics were so different. Taking The Traveller Book off my shelf, I see that you're right: passenger and cargo prices are the same irrespective of jump distance! That disincentivizes merchant ships from having larger drives - there's more profit to be made with a jump 1 drive than a jump 6.
In that world, the Gazelle's drop tanks make sense - it's a military ship. (Although it doesn't explain why it's the only ship in Supplement 9: Fighting Ships to have drop tanks.)
However, the economics of 1981 Traveller don't make sense to me. If there's a competitive advantage in getting goods from A to B in one week as opposed to four, then surely that's worth paying for. (But I've only dipped a toe into 1981's Traveller, so I don't know if economic balancing happens elsewhere.)
Mind you, the Mongoose 2nd Edition economics don't work either, as competition would soon bring profits down on those J6 routes. But if they could be somehow maintained (Imperium price fixing, perhaps), then it would create a very interesting hub-and-spoke model for an interstellar empire.
So, do I still think the Gazelle is a mistake? Maybe not originally (although the economics do look odd, and where are all the other ships with drop tanks?), but now? Something's still not right about it.
I think the reasoning behind the Gazelle having drop tanks was down to its intended roles.
DeleteIn the convoy escort and anti-piracy patrol roles, it doesn't need to do more than J2, so the drop tanks aren't needed (except, perhaps) for the initial jump to the convoy/patrol start point. The small increase in MD rating at 300 dTons is a benefit in this role.
In the fleet escort role, it needs the J4 to be able to move with the capital ships it is meant to be defending and the drop tanks won't be dropped. However, the lower MD rating makes it less useful in this role as it can't accelerate as fast as the ships it is meant to be defending, unless it is defending the ships in the reserve (tankers, transports, tenders, salvage, etc) but it still has a lower acceleration than likely threats to them.
TamsinP wrote (but it hasn't appeared for some reason): "The Gazelle was designed to fulfill two main roles:
ReplyDelete1. Convoy escort/anti-piracy patrol. In this role it doesn't need more than J2 capability, which it still has without the drop tanks. The increased acceleration without them is a benefit.
2. Fleet escort. In this role it does need the drop tanks to sustain J4 capability to move with the fleet. However, the lower acceleration means that in combat it would have trouble staying with the capital ships and wouldn't be much use against fighters and other small combatants; it's most likely role is close protection for the reserve line ships (tenders, carriers, tankers, transports, etc).
Whether that is how the original designer intended them to be used is another question.
Cost/Benefit analysis would need to take the multi-role nature of the class into consideration, as well as the fact that it is a military vessel rather than civilian.
Looking back, the drop tanks first appeared in LBB5 (80) which was published before JTAS 4."
I've just noticed in Fighting Ships that it says this about the Gazelle: "Hundreds of Gazelle class close escorts have been built and many remain in service in the Imperial Navy, despite the fact that in a combat situation, they are nearly worthless. The close escort, even when new, was not intended to stand up to combat vessels; rather it was envisioned as an anti-piracy and revenue patrol ship. In that role, it has performed well, but when pressed into combat duties it has invariably suffered disproportionate losses."
ReplyDelete(Doesn't explain the lack of drop tanks elsewhere, though.)
Both JTAS 4 and Traders and Gunboats were published in 1980. I think I'd read somewhere that JTAS 4 came first, but as that's hearsay, you may be right.
As mentioned, I think High Guard must have been published before JTAS 4 and Traders and Gunboats (unless the person who designed the Gazelle received an advanced copy of High Guard).
ReplyDeleteHigh Guard was also 1980 - I think it was all happening at the same time at GDW.
ReplyDeleteAh, I stand corrected. According to my 1980 pdf of High Guard, "This book is a substantially improved and re-typeset edition of High Guard, Traveller Book 5, which originally appeared in 1979. It contains additions, corrections and changes to the starship design and combat rules (pages 17 to 52)." I don't know whether drop tanks were included in the 1979 edition, but they're definitely in the 1980 edition. 1980 is also the publication date for JTAS 4 and Traders and Gunboats, both of which feature the Gazelle. (It crosses my mind that High Guard might have been revised in 1980 to include drop tanks, but I can't confirm either way.) I've amended the text above.
ReplyDelete