Author Topic: DropShips and planetfall  (Read 3267 times)

BritMech

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DropShips and planetfall
« on: 14 April 2012, 18:31:32 »
In TRO 3057, it says that the Mammoth class are the largest DropShips that can make planetfall, and they have a mass of 52,000 and a Thrust of 3/5. The Behemoth has a mass of 100,000 and a Thrust of just 2/3.

I was wondering which of these (or anything else) is the limiting factor, and therefore would it be possible for a 100,000 ton DropShip to make planetfall if it had a thrust of 3/5 or more? For that matter, would gravity alter the minimum needed to take-off? I assume that provided the Safe Thrust is equal to or greater than the gravity of the planet, it can take off just fine, although the close they are to balanced opposing forces the slower the take-off is going to be and the more fuel is used up due ot gravity drag.

Edit: Having found the rule in TW that says you need a Safe Thrust over 2 to take off, this should probably be in the Developers section.

So now the question is more: Why Safe Thrust 3 to take off from a normal planet? Anything equal to the gravity of the planet would be enough to remain neutral, and anything over neutral means you can get off the planet, with more thrust meaning quicker take-off. So why isn't the minimum SF 2 instead?

Because Safe thrust is not the maximum they can put out, it could even be argued that a safe thrust equal to the gravity means that a take-off is possible, since the gravitational pull gets weaker as it moves away from the planets surface.
« Last Edit: 14 April 2012, 19:32:30 by BritMech »

HABeas2

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Re: DropShips and planetfall
« Reply #1 on: 14 April 2012, 20:14:02 »
Hello,

A Thrust Point = 0.5 G, so a Safe Thrust of 2 would not overcome the effects of planetary gravity, meaning a Safe Thrust of 3 is needed to overcome terrestrial gravity (many BattleTech worlds, however, are slightly above the 1.0 G standard of Terra, meaning your typical DropShip probably looks to that extra .5 G as "padding" as well).

While it is true that MAXIMUM Thrust of a DropShip with a Safe Thrust of 2 = 3 Thrust Points, Maximum Thrust causes handling problems (most of which tend to be communicated as modifiers in combat), and so it is considered incredibly reckless to be attempting operations in a gravity well where you need maximum thrust just to get around (especially one with an atmosphere).

Ultimately, the "rule" that limits a DropShip from making planetfall is fluff, and Strategic Operations communicates this as a Design Quirk such vessels may receive to explain their inability to handle atmospheric operations and the like.

Hopefully, that helps.

Thank you,

- Herbert Beas
  BattleTech
  Catalyst Game Labs

BritMech

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Re: DropShips and planetfall
« Reply #2 on: 14 April 2012, 22:14:22 »
Hello,

A Thrust Point = 0.5 G, so a Safe Thrust of 2 would not overcome the effects of planetary gravity, meaning a Safe Thrust of 3 is needed to overcome terrestrial gravity (many BattleTech worlds, however, are slightly above the 1.0 G standard of Terra, meaning your typical DropShip probably looks to that extra .5 G as "padding" as well).

While it is true that MAXIMUM Thrust of a DropShip with a Safe Thrust of 2 = 3 Thrust Points, Maximum Thrust causes handling problems (most of which tend to be communicated as modifiers in combat), and so it is considered incredibly reckless to be attempting operations in a gravity well where you need maximum thrust just to get around (especially one with an atmosphere).

Ultimately, the "rule" that limits a DropShip from making planetfall is fluff, and Strategic Operations communicates this as a Design Quirk such vessels may receive to explain their inability to handle atmospheric operations and the like.

Hopefully, that helps.

Thank you,

- Herbert Beas
  BattleTech
  Catalyst Game Labs

So when dealing with High Gravity worlds, it would make sense to say that the [Safe Thrust] / [Planet Gravity] = [New SF] should be over 2 as well then? So a 2g world needs a craft with a normal SF of 5 to take off, and a 2.5g world needs a craft with an SF of 6?

HABeas2

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Re: DropShips and planetfall
« Reply #3 on: 14 April 2012, 22:44:32 »
Hello,

I believe rules covering different gravities and how they affect movement appear in Tactical Operations.

Thank you,

- Herbert Beas
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BritMech

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Re: DropShips and planetfall
« Reply #4 on: 15 April 2012, 00:09:39 »
The gravity rules seem more focused on movement on the map, which is why I asked about take-off. Really it's about the rounding in the High/Low Gravity. For movement it makes sense, since you can't move 0.3 hexes. But would you round for the purposes of a take-off calculation? If so, the Safe Thrust 5 ship is going to get stuck on the 2g world, whilst it wouldn't if you just did the straight calculation. Ditto the ST 6 ship on the 2.5g world.

HABeas2

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Re: DropShips and planetfall
« Reply #5 on: 15 April 2012, 00:14:50 »
Hello,

Yes, that would be logical.

Thank you,

- Herbert Beas
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  Catalyst Game Labs

BritMech

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Re: DropShips and planetfall
« Reply #6 on: 15 April 2012, 03:00:12 »
Yes, that would be logical.

Sorry, I'm not sure which bit you are referring to. Should you round down for take-off or not?

BritMech

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Re: DropShips and planetfall
« Reply #7 on: 17 April 2012, 16:13:41 »
Sorry, I'm not sure which bit you are referring to. Should you round down for take-off or not?

See, if I posit the question "Can a DropShip with 5 Safe Thrust take off from a 2g planet?" then I get this:

Argument For: 1g = 2 SF. 2g = 4 SF. 5/4 = 1.25, so whilst slow, the ship could achieve lift and break atmosphere.

Argument Against: Tac Ops says that you should divide by the gravity, rounding down at .5 and thus 5/2 = 2.5, so 2. Which means it couldn't take off. However, this rule is for moving around on the planet, and that requires whole numbers.

My preference would be the Argument For. It allows a wider variety of ships to travel between higher gravity worlds. But I'm curious which applies according to BT staff, particularly when we realised this applies to Conventional and Aerospace fighters as well. It has good potential for fighters being dragged to earth because of gravity pockets caused by fragments of an exploded neutron star or somesuch.

HABeas2

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Re: DropShips and planetfall
« Reply #8 on: 17 April 2012, 21:12:26 »
Hello,

The rule applies, so the rounding down take precedence. Fact is, after a certain point, we tend to feel that playing with the numbers gets obnoxious (which is one reason why, even though Fractional Accounting is a rule we allow for advanced users, we simply do not employ it for most canon designs).

Thank you,

- Herbert Beas
  BattleTech
  Catalyst Game Labs