Of Backpacks and Powerarmor

[bladeofdeath3]

I guess it really depends on the artists who portray the primarchs in their armor. I'm 99% sure the primarchs are wearing power/terminator/artificer armor. In the Forgeworld Horus Heresy Book, each primarch has a named suit of armor. For Horus, it's called "The Serpent's Scales" and is described as "Horus' unique suit of terminator armor". Fulgrim's "The Gilded Panoply" is described as artificer armor and Mortarion's "The Baraban Plate" is a "of his own design, fusing power armor technology with his own lore". Keep in mind that they all have 2+ saves. The only primarch so far which doesn't have power is Angron, who has the "Armor of Mars" which is described as being "modified from his gladiatorial armor in which he fought as a slave". Sadly, Angron only has a 3+.

As for the backpacks, none of the forgeworld primarch models have backpacks. I suppose that the primarchs would have access to the best technology the Imperium had to offer at the time. Horus' terminator armor was described as having been designed and continuously improved by Kelbore Hal, the Fabricator General of Mars at the time. I'm sure they could design power armor without the need for a backpack power source. I'll go out on a limb and say the Forgeworld books and models are official depictions of the primarchs since they are directly put out by GW. The HH book series depictions can be very inconsistent since there are a lot of artists who design covers.

[Nabterayl]

I'm inclined to go with bladeofdeath3 on this one. I think it is power[ed] armor, just with a power source small enough that we don't notice it on the models. I do think the HH covers are good evidence that they are compatible with backpack power sources, though, and probably environmental sealing as well, at need.

[Cpt Codpiece]

it may well be a factor or the primarchs will animates the suit, kind of like guardian/aspect suits.
all of the primarchs have had some dabbling with their code (they are artificial beings made form an artificial being), its no real shock to see angron not in a psychicly powered suit, as he messed with psychers minds, even the emperor and magnus..... a sign that he was touched by khorne.

[Dlatrex]

Yeah; in Know No Fear, they explicitly discuss Papa Smurf as missing his helmet, and the consequences that follow. He also DOES later don a helmet covered with Aquillas when he intentionally goes into combat.

We also know at least Alpharius has multiple suits of armour (big surprise), so I guess the best we can say is "some did, and some didn't and some probably had both!" Lol.

Now, are there any cases of line men Astartes missing their backpacks?

[bladeofdeath3]

It seems like every version of power armor from Mk 1 to Mk 8 used a backpack power source. Even the Grey Knights power armor has backpack power sources. The only "troops" whose armor does not have backpacks are the Adeptus Custodes. This seems more plausible as they probably would have access to about the same equipment as the primarchs. It seems very implausible that line troops wouldn't have their backpacks as the backpack does more than only house the power source. It seems like the oxygen and air purification systems are in the backpack, which would be useful for astartes in hostile environments. Seeing as the mightiest heroes of the Imperium wear backpacks with their armor, it would seem silly that line troops wouldn't...

[Rev. Tiberius Jackhammer]

One of the Forgeworld books (I think it was Taros?) mentioned that normal power armour can sustain itself for several weeks without a backpack, but must deactivate pretty much everything besides mobility and life-support.