Moving a armor BN into the attack

[Colt Ward]

As part of a map campaign, my opposition can move a battalion and a half of armor into the attack.  The formed BN is mostly Po Heavy Tanks, Bulldogs, Goblins and Condors along with a few SFE equipped tanks, which means they will need fuel to move and attack.  And likely need to refuel after a battle if they press on.  The half is a ad hoc force made up of Vedettes, Scorpions and other low-end combat vehicles- a green unit.  They will also need fuel and might be better off used to guard supply convoys or re-arming points as well as scouting down country roads.

My forces have some limited armor and the rebels they are supporting have Vedettes & Scorpions they captured or bought from offworld that will be used for defense.

But how much fuel would you expect a armor BN need to go 50 standard map sheets along a road?  Over open terrain & rolling hills with woods?  Through mountain passes?  The attackers will also need fuel to move their own infantry's supplies up to the city (if they reach it) to clear it of rebels . . . though they can use LPCs to get there.

4 Heavy BM recovery vehicles
2 BM Recovery vehicles
4 BFFL hovertrucks w/armor & myomer
4 J-27 Ordnance Carriers
4 Heavy Tracked APC as ammo carriers
8 Sherpa
6 Flatbed
3 Lewis Skimmer Bus (Techs & tools)
2 Engineering Vehicles
8 Coolant trucks, mark 6 as fuel
2 BFFL hovertrucks w/fuel containers

Came in as a supply run though a few vehicles were lost to raiders, I will have to look up what exactly was lost- I think a Sherpa or two, maybe some Flatbeds and a Coolant Truck.  Assume the attackers foraged across the rebel's country-side taking food & fuel to their firebase before the relief column arrived.

[Death by Lasers]

  Lets see, per Strat Ops 35 combat vehicles dedicate 10% of their "engine mass" to fuel.  Per the TechManual ICE vehicles get 100km at cruising speed per 1% engine mass in fuel.  Since you get a free MP traveling on the road you are going to get maybe 120km per 1% for road travel and maybe 50km per 1% for travel over hilly terrain (assuming you are making 9 elevation changes per map sheet).  A mapsheet is about .5 km so 50 of them would be about 25km.  In simplest terms to travel that distance you would need a base of 0.25% of engine mass per vehicle in fuel.

  For your supply column I worked out it would need somewhat less than about a half ton of gas and a half ton of hydrogen for the trip.  For your armored battalion I would say, using the Vedette as a base, you will need a little over a ton in fuel over flat terrain, a little under a ton if using a road, and perhaps 2.5 tons for traveling over rough elevations (BASE: 12.5 ton ICE x 36 vehicles x 0.0025 distance).

[Colt Ward]

Yeah, but that is travel.  IIRC 'combat' has different fuel requirements, where the vehicles basically guzzle fuel b/c of the different demands on the engine.  It was also more of a opinion question, I know some player's attitudes who would leave the tanks sitting back at the base and use the mechs for the combat if they thought the mechs could handle it.

[Death by Lasers]

  Ah, misunderstood your question.  According to Strat-Ops fuel usage is on pg. 35 and assumed to be 2% engine mass per scenario or 8 times what I put forward for simple movement, so that would be maybe 20 tons of fuel.  Seems legit if you are involved in a bunch of maneuvering and fighting. 

  You could use WWII fuel consumption rates for tanks in combat.  I'm pretty sure the statistics are somewhere.  I remember from some documentary a soldier describing the tanks in the pacific moving forward like a 'fat kid trying to ask a girl out at the prom', that is tentatively moving forward slowly then backing up quickly and then moving forward slowly again.  I could see that using up a bunch of fuel after several hours.  Being a game and all though most Battletech fights tend to resolve themselves into crazed 2 minute long slaughters.

[Colt Ward]

I agree, but the reason to ask if for the strategic movement of assets . . . sure your mechs maybe able to walk there, but if after a few actions your Victor 9Ks are out of Gauss Rifle rounds and you spent the fuel on moving Vedettes rather than re-arming trucks . . . Well, it does not matter how far forward your Victors pushed if they have to turn around to walk back to somewhere several map sheets away to reload.

[Kovax]

At somewhere around a gallon per mile, and about 8 lbs. per gallon, 36 vehicles would burn very roughly on the order of 200 lbs. of fuel per km.  For 50 mapsheets, 17 hexes at 30m per hex, that's 28.5 km, and will require almost 3 tons of fuel.  One fuel truck should easily carry enough for the trip.  Depending on how much more or less fuel efficiency the tanks get versus 1mpg (probably close to that on road, half the efficiency off-road, and significantly less in combat), that should give you a ballpark estimate on how limited they are (or are not) by fuel considerations.

[Nebfer]

Well Historically your going to need to set up supply dumps, and also most attacking armies seem to peter out after a few hundred km anyway due to out running supply lines.

Current rules seem to indicate that a Combat Veh with a non fusion or the rare fission engine spend 10% of their engines mass of fuel, and get 667 or 1,000km per fuel tank (Fuel cell / ICE), at lest while driving around, though this seems to be cross country and not road travel.

A few examples the 45 ton Goblin has a 14 ton engine, so it uses 1.4 tons to travle 1,000km, at 1,333 liters per ton it gets 1 km per 1.86 liters *
The 50 ton Musketeer Hover Tank has a 10 ton ICE engine, so it has a 1 ton fuel tank (1.33 liters per km)
The 50 ton Vedette has a whopping 25 ton engine or 2.5 tons of fuel I would think not to bad for a unit going at lest 86kph off road or 3.33 liters per km
The Bulldog has a 23 ton engine so 2.3 ton fuel tank to move it at 64kph off roads (~3.06 liters per km)
The 95 ton Ontos has a 33 ton engine moving it at 54kph off road, and I believe has the largest fuel tank/ICE engine of any combat vehicle in the game. Using roughly 4.4 liters of fuel per km

The Condor has a 12 ton engine so 1.2 tons of fuel
The Po has the same engine specs as the Bulldog

* For reference an M1A2 has 1,900 Liters of fuel (roughly 1.5 metric tons worth (3,250lb at 6.5 lb per gallon (of jp8) and 500 gallons in the tank)) and gets roughly 430km per tank on roads, supposedly it gets 0.6 MPG and uses 60 gallons per hour cross country which is listed at having a top speed of 30mph (the listed (and rumored) higher speeds are for road travel not cross country)).
Basically the M1A2 gets roughly 4.4km per liter. At a max off road speed of about 48kph (I do not know what the ungoverned speed is when off roading, though one Army Tank once told me that 30mph is a bit optimistic in his experience, all I can find is that the ungoverned road speeds seems to be around 80mph or 128kph, with a governed speed of 42mph or 67kph). Basically using the governed speeds I would argue the M1A2 is 3/5 (+1 for road travel per the rules, one could likely add the other +1 MP for Tac ops sat Nav satellites).


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As for Combat use rates, theirs no real good value for that, Strat ops dose have the 1/5th of a tank for a scenario with combat, so one could argue that combat consumes 100kms worth of fuel on top of 100kms worth of travel, though one has to ask how long is that combat going to be?

The Battalion Support companies of current US army Armor Brigades (Circa 2007) have a Supply platoon with 12 M978 Fuel tankers, as well as a 22 more at brigade level (~55 total in the Brigade).
Each fuel tanker carrys ~7.5 tones of fuel (2,500 gal)

In any event I would say that it would not be out of the place for the units supply elements to carry enough fuel for a complete reload, so a Ontos Battalion would need 132 tons of fuel for the tanks (3.3 tons x 40), more would be required for the other vehicles in the unit (personnel & cargo carriers, command units, and what nought).

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Per your scenario of a convoy moving 25ish km, I would say as it seems to have saw combat roughly 50ish km worth of fuel, roughly 3 to 6 tons of worth for a battalion of tanks.