Author Topic: (Answered) Error in towing calculations (or in Worktroll's brain)  (Read 2140 times)

worktroll

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Folks,

Was just working out some figures for a custom vee, using the TechManual rules from P101 of TechManual, v1.2 (CAT35001):

Quote
Tractor/Trailer Vehicles: Combat Vehicles with a Tracked or Wheeled motive type may be built as Trailers. Trailers do not require an engine, control systems, or crew, unless they are also expected to operate without a suitable Tractor unit or are expected to employ heavy weapons and equipment while operating independently of a unit with an engine (in which case, a minimum Engine Rating of 10 applies).

The MPs of a combined Tractor/Trailer unit may vary during gameplay. The Cruise MP of a  combined Tractor/Trailer unit is equal to the Engine Rating of the primary Tractor unit (the one doing all the towing/pushing), divided by the combined weight of the Tractor and its Trailer(s), after subtracting the lowest Suspension Factor of the combined units (rounded down). The Flank MP is then computed normally by multiplying the Cruise MP by 1.5, and rounding up to the nearest whole number. Thus, a 65-ton Tracked Tractor with an Engine Rating of 260 (Suspension Factor 0), towing a 20-ton Wheeled Trailer (Suspension Factor 20), would have a combined Tractor/Trailer MP of 3 Cruise, and 5 Flank MP (Engine Rating 260 / [65 Tractor tons + 20 Trailer tons - 0 Tractor's Suspension Factor] = 3.06, round down to 3MP; 3 Cruise MP x 1.5 = 4.5MP; round up to 5 Flank MP).

So let's take that equation:

Engine Rating / [mass of tractor + mass of trailer - worst suspension factor]

Now let's apply this to a 15-ton wheeled tractor and a 5-ton wheeled trailer. Suspension factor for both is 20, the standard for wheeled. The tractor moves at 5/8, which means an engine rating of (15x5 -20), or 55.

So when our 15 ton truck hooks on a 10-ton trailer, the new speed is ... according to the formula ...

Engine Rating / [mass of tractor + mass of trailer - worst suspension factor]
55                / [15                   + 10                  - 20]
55 / [25 - 20]
...
11?  ???

Not sure what's in that trailer, but can my recon units have some? :D And if I'd hooked on a 5-ton trailer, would I have invented a new form of superluminal travel?

Yes, the example works, but only because suspension factor is 0.

Recommended fix: formula needs to be

[Engine Rating + lowest Suspension Factor] / [Tractor weight + Trailer weight]

So in the above example it's

[260 + 0] / [65 + 20]
260 / 85
3.06 = 3

Or for my example, it's

[55 + 20] / [15 + 10]
75 / 25
3.00 = 3

So ... am I in error, or the book? Was not able to find a previous report, using the forum's search function.

W.
« Last Edit: 06 December 2017, 18:18:52 by Xotl »
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worktroll

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Re: Error in towing calculations (or in Worktroll's brain)
« Reply #1 on: 02 February 2017, 20:27:21 »
In the most polite, and never passive-aggressive style ... bump?
* No, FASA wasn't big on errata - ColBosch
* The Housebook series is from the 80's and is the foundation of Btech, the 80's heart wrapped in heavy metal that beats to this day - Sigma
* To sum it up: FASAnomics: By Cthulhu, for Cthulhu - Moonsword
* Because Battletech is a conspiracy by Habsburg & Bourbon pretenders - MadCapellan
* The Hellbringer is cool, either way. It's not cool because it's bad, it's cool because it's bad with balls - Nightsky
* It was a glorious time for people who felt that we didn't have enough Marauder variants - HABeas2, re "Empires Aflame"

Xotl

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Replace
Quote
The MPs of a combined Tractor/Trailer unit may vary during gameplay. The Cruise MP of a  combined Tractor/Trailer unit is equal to the Engine Rating of the primary Tractor unit (the one doing all the towing/pushing) plus the lowest suspension factor of the combined units,, divided by the combined weight of the Tractor and its Trailer(s) (rounded down). The Flank MP is then computed normally by multiplying the Cruise MP by 1.5, and rounding up to the nearest whole number. Thus, a 55-ton Wheeled Tractor with an Engine Rating of 260 (Suspension Factor 0), towing a 20-ton Wheeled Trailer (Suspension Factor 20), would have a combined Tractor/Trailer MP of 3 Cruise, and 5 Flank MP (Engine Rating 260 / [65 Tractor tons + 20 Trailer tons - 0 Tractor's Suspension Factor] = 3.06, round down to 3MP; 3 Cruise MP x 1.5 = 4.5MP; round up to 5 Flank MP).

with
Quote
The MPs of a combined Tractor/Trailer unit may vary during gameplay. The Cruise MP of a combined Tractor/Trailer unit is equal to the sum of the Engine Rating of the primary Tractor unit (the one doing all the towing/pushing) plus the lowest Suspension Factor of the combined units, then divided by the combined weight of the Tractor and its Trailer(s) (rounded down). The Flank MP is then computed normally by multiplying the Cruise MP by 1.5, and rounding up to the nearest whole number. Thus, a 15-ton Wheeled Tractor with an Engine Rating of 55 and Suspension Factor 20, towing a 10-ton Wheeled Trailer (Suspension Factor 20), would have a combined Tractor/Trailer MP of 3 Cruise, and 5 Flank MP ([Engine Rating 55 + lowest suspension factor of 20] / [15 Tractor tons + 10 Trailer tons] = 75/25 =3MP; 3 Cruise MP x 1.5 = 4.5MP; round up to 5 Flank MP).
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