Sentinel Endurance

[Nabterayl]

Question for the collective lore-mind: how long can Sentinels operate on a full tank of prometheum?

I know that they're used for reconnaissance, but that doesn't necessarily tell us anything - Salamanders are also used for reconnaissance, and, as a tracked vehicle, I'd be surprised if they had a range of more than about 480 km on a single tank (and I'd be surprised if they had that much endurance, Imperial armor being the extremely mobile thing that it is ).

The fact that the Guard still uses rough riders for reconnaissance is somewhat probative of Sentinels having limited endurance, since cavalry - while certainly logistically intensive - can operate away from supply for days at a time as long as they don't push their mounts too hard, whereas an out-of-fuel Sentinel is just a nifty jungle gym. It can't be too probative, though, since the Departmento Munitorum is clearly happy to recruit horse cavalry from horse cavalry-using worlds (i.e., if you're stuck with horse cavalry as a Guard commander, using them for reconnaissance is an obvious way to make a virtue of necessity).

Does anybody have any instances of Sentinels operating, without resupply, for any length of time? Even a day? Or outright stats that I'm ignorant of?

[bfmusashi]

I'm actually surprised to see this isn't covered in Rogue Trader: Into the Storm. The only instance I can give is a Ciaphas Cain book where a Techpriest rigs up an extra fuel tank and flame thrower onto a power lifter. I think it's mentioned it ran for several days even after she torched some orks.

[Chris*ta]

Sort of related ...

My impression from, say the IG Armour list in WD 295, is that sentinels are by far the favoured choice for recon. We can infer then, that sentinels are better than the other options, (i.e. rough riders and salamanders). This would be partly because sentinels can handle terrain that the others could not, partly because of speed, (ultimately, cavalry is not that much faster than infantry) and also endurance. I do get the impression that sentinels have very good endurance though.

This is complicated by the issue regarding availability of the various units. While salamanders are organic to armoured regiments, (and possibly a small number to infantry regiments) rough riders are almost always in their own units independent of other regiments. As for sentinels, the sources vary, sometimes they're said to be organic to infantry regiments, sometimes they exist in their own separate units.

[Nabterayl]

I agree that the evidence tends to show the Sentinel as the favored reconnaissance platform. I found two more points of interest since the OP: on Taros, the Elysians' sentinels lasted for three days of fighting without resupply, and the codex speaks of Sentinels often being deployed "far" from supply. Of course, it doesn't say how long they can operate far from supply, but that does tend to suggest that endurance is not considered a very limiting factor. And the Elysian mission to the water plant gives us a reasonable floor of three days' endurance - perhaps more if, as is often the case with vehicles, combat conditions are less fuel-efficient for a Sentinel than simple travel.

[bfmusashi]

Didn't there used to be a mention that the IoM's engines can run on almost any combustible? Promethium is just a preference but they truly have universal fuel engines in all their machines?

[Chris*ta]

I would assume in that case, they were dropped with extra-large fuel tanks, and possibly with an additional supply of fuel.

Even so, evidence points to sentinels being able to operate for extended periods -- more than one day, I think -- away from ready supplies.

[Chris*ta]

Didn't there used to be a mention that the IoM's engines can run on almost any combustible? Promethium is just a preference but they truly have universal fuel engines in all their machines?

Yeah, there's mention of Leman Russes operating as woodburning on occasion, iirc. In WD 295, I think. I might look it up later. I take it to be that they're not that different to modern day diesel engines.

[Nabterayl]

Some sources have indicated that "promethium" itself is just a catch-all name for "combustible liquid." The stuff that you put into a flamer and the stuff you put into your gas tank aren't necessarily the same substance, even though they are both "promethium." Heck, the stuff you put into your gas tank isn't necessarily the same as the stuff your neighbor's putting into his gas tank. I think if you were used to your fuel tanks being able to run on almost any liquid, you might well stop using different words for them, unless you were a specialist in the fuel field.

[Chris*ta]

I get the distinct impression that promethium means the same thing as "petrol" or, for Americans, "gas". That is, it refers to any processed dead dinosaur that acts as fuel, and is a catchall term for regular, unleaded, premium, diesel, napalm and avgas.

There's a couple pages on promethium in one of the early Cain novels, I'll see if I can be bothered looking that up at some point, but I'm quite busy this week.