Rigel Stardin
SOC-13
Maybe I'm dense, but is there a maxium size on drop tanks?
Are there penality for holding onto empty drop tanks during combat?
Are there penality for holding onto empty drop tanks during combat?
Drop Tanks for Starships
- Thread starter Rigel Stardin
- Start date
mike wightman
SOC-14 10K
They can be as big as you like providing your degraded drives still have a rating of 1 or more.
They reduce drive performance while in combat unless dumped.
They reduce drive performance while in combat unless dumped.
As I understand, drop tanks augment the tonnage of the ship, with the Drives, batteries bearing, and so on recalculated.
Aside from that, you can carry (IMO) as large drop tanks as you want, just there's a point from wich your ship cannot maneover.
Aside from that, you can carry (IMO) as large drop tanks as you want, just there's a point from wich your ship cannot maneover.
No. But as McPerth suggests there are practicle limits, but if you are not concerned with maneouvre... If playing a ref run game (or you are the ref), as you are looking at oversized DT's, get a ruling to clarify whether the ship size, including the DT, must be under the computers limit ship size limit. HG is ambiguous & its better to get agreement early.
In HG yes. The DT reduces your MD & PP ratings, which in turn reduces your Agility. And if you take a damage roll, un-modified by armour, that causes a fuel-1 hit, your DT's are destroyed.
There are two ways to use DT's to get range.
- The first involves using all the fuel up in the first "burst" to get into jump, dropping the tanks and jumping normally with the ships normal (non DT carrying) Jump rating. The ship will usually still have internal jump fuel capacity to make a second jump once it reaches its destination. The DT's are generally considered to be destroyed (again HG is ambiguous, but later editions adopt this convention).
- The second involves jumping with the DT, using fuel carried in the ship. This reduces the ship's (with DT) jump capacity due to carrying the DT, but potentially increases range due to more fuel being carried. After fuel is used in the internal tanks, it is pumped from the DT's to replace it.
But make sure your combined design doesn't run afoul of the computer limits and/or get a refs clarification, being sure to mention that carrying the DT's through jump, will be more or less "normal".
Cheers
Rigel Stardin
SOC-13
Here is my thought on the subject.
I'm building a ship at the moment that has two drop tanks. They are large somewhere in the 50 to 100+ range combine tonage. My thought process at this moment is, if they weigh 10% of the fuel volume (10 ton tank for every 100 tons), the weight is really isn't an issue considering the starship's overall weight will be between 800 and a 1000 tons. The ship will get a penality when the tanks are full but not after the fuel has been spent. Since the tanks will be mounted over the engineering section, an empty tank would absorb some of the damage (when empty) caused by weapon hits.
If someone can point me the caculation for a Drop tank weight, it would help me greatly...
I'm building a ship at the moment that has two drop tanks. They are large somewhere in the 50 to 100+ range combine tonage. My thought process at this moment is, if they weigh 10% of the fuel volume (10 ton tank for every 100 tons), the weight is really isn't an issue considering the starship's overall weight will be between 800 and a 1000 tons. The ship will get a penality when the tanks are full but not after the fuel has been spent. Since the tanks will be mounted over the engineering section, an empty tank would absorb some of the damage (when empty) caused by weapon hits.
If someone can point me the caculation for a Drop tank weight, it would help me greatly...
In TNE FF&S or T4's FF&S II the drop tanks are designed like a seperate hull, but with 1/4 the armour (armour 5 instead of armour 20). As the mass required for each armour level changes depending on tech level, the number of g's it needs to handle requires internal bracing, and the streamlining affects capacity. I'd need to know if you are streamlining the ship, what configuration you need, how many g's, at what TL, and how big you need the tank.
P.S. a 50 "ton" tank in these rules will not quite hold 50 tons, you'll likley be 1/2 a ton short, or need to oversize the drop tank a bit. Drop tanks need to be grappled to the ship, and the grapples are designed with the same streamlining of the hull, or you lose the streamlining.
An external demountable tank is designed much the same way but has armour 10 and no grapple requirement, and is fitted with explosive bolts if you desire to be able to jettison the cargo/fuel.
A typical FF&S designed ship will mass about 1 Mt per cubic meter, warships will come in higher than this and cargo ships somewhat lower, and ships with high jump numbers significantly lower. An external demountable fuel tank will mass approximately .1 mt per cubic meter full of fuel. You could double the ship's size with such a tank and yet increase the ship's mass by only 10%, however you will need double the jump drive and power plant to maintain the jump capacity, but only 10% more maneuver drive to maintain the same g rating.
De-rating example: 100 Dt J6 ship needs to cross a rift and is fitted with 250 tons of demountable tanks, for a nominal 310 Dt of fuel.
The jump drive (7 Dt) is derated down to J-1 (7 Dt is 2% of 350 Dt) using 35 tons of fuel for the jump.
After each jump the crew goes EVA and dismounts a tank that held just enough fuel for the previous jump, each additional jump uses less fuel till you have shed enough tankage to go to the next higher jump number.
350 = J1 uses 35
315 = J1 uses 31.5
283.5 = J1 uses 28.4
255.1 = J1 uses 25.5 **
229.6 = J2 uses 45.9
183.8 = J2 uses 46.6 **
137.2 = J4 uses 54.9
100 = J6 but only enough fuel for J4 remains
and there you have crossed a 16 parsec rift without refuelling!
(17 parsecs if you used a drop tank for the first jump)** use drop tank at this point to jump at a higher rating
Can please tell us where did you find this rule? I don't remeber having readed it, though I find it quite sound and logical.
I had to hunt a little...TCS pg 14 "Drop Tanks" last paragraph.
FWIW, I also reread the "disposable tanks" rule in HG, I take back what I said about HG being vague on DT's being destroyed when dropped at the start of jump.
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