so soon I will start my OW campaign in which the squad is part of an Armoured Regiment. They will start play with a Leman Russ battle tank.

My question: do we assume the entire squad fits into here? or do we adher to carrying capacity and is it generally so that Leman Russ tanks are followed on foot by those hapless comrades and squad members that don't fit in after all PCs have taken their places?

I have four PCS and so far four comrades, so 8 in total.

I'd say you have four options here:

The players share one tank, Comrades man a 2nd one. This has the advantage of keeping the players together in their little tin, and they can use their Comrades' vehicle as cover or to take the worst of a beating. After all, normally Comrades have a chance at "catching a bullet" for a PC, but with a tank this option does not exist in the same way. Giving the Comrades their own tank reintroduces this perk.

Each tank is manned by 2 players and 2 Comrades. This allows two of your players to act as drivers, and two to act as tank commanders. The Comrades are all Gunners and will man the turret and hull weapon.

Take a Leman Russ with sponsons (for a total of 6 crew), and just forget about the remaining 2 Comrades. Assign the two Comrades who still find room based on what their players are doing, meaning, in a way that each of your players has as much stuff to do as the next one. For example, you could have the driver and the hull gunner each gain a sponson gunner in addition to their primary job, whereas the tank commander and the turret gunner do not, because their position is already awesome enough (one gets to shout orders and tell everyone what to do, the other gets to fire the biggest cannon of 'em all).

The players crew a tank, Comrades are infantry who sit on the back. The NPCs will dismount upon combat and assist the vehicle. Soviet Valhallan-style:

(note that the last two options necessitate houseruling the type of Comrade a player class gets)

For me it'd be more interesting to have players both inside and outside the vehicle. Both dramatically and tactically, having a fire team riding atop the russ during narrative travel, hugging the tank at times for cover, or running to engage enemies with powerful anti-tank weapons inside a building. Provided the players are equipped properly.

On the other hand IIRC the standard leman russ has a crew of 6. So stretching it to 8 would only be minor heresy. If you wanted to go a different route, you could also give the squad a small light vehicle the others can run around in, like a salamander.

Generally, If I run an Armored regiment I assume the players are all operators and run 2 or three per tank (Depending on sponsons. This allows a full tank crew of 4 or six with comrades. Players generally play Driver, Main gunner and Tank Commander with Comrades filling out loader and sponson gunner roles (The comrade advance allows them to fire the weapon as if the operator was in their place.). In your case I would suggest 3 operators and one Engineseer (Complete with powered armor in this environment! who would follow in a Chimera crewed by NPC's. Running an Armored regiment game is actually pretty tough unless you know how actual Tank warfare works in real life. A tank when you break it down is not that different from running a voidship battle in RT although on a much smaller scale! While the tank is rolling from on place to another it is essentially a very large car with VERY bad handling characteristics. Once in combat though, Things change! Each character has a specific role to accomplish. The tank commander is responsible for identifying targets and threats either visually or with various onboard sensors (Basically an onboard Auspex). All while directing the rest of the crew! The Driver is responsible for moving the tank (Obviously!) and also trying to place the tank in hull down cover positions or at least not unnecessarily exposing it's weaker flanks. The Main gunner Responds to targeting orders from the TC and "lays" the main gun (Sets which angle it is rotated to. The RAW says that the turret can rotate 180 deg. per turn but I treat each 90 deg. as a half move.) and gets to fire the Big Gun! The secondary weapons on sponsons and hull are operated by comrades as if the PC were in their place. They are able to react faster but their fild of view is typically very limited by the weapon arcs.

Part of it depends on the scenery and set-up, as it were. In most cases, a solo tank with just enough guys isn't rolling along alone, but part of a group. Your extras (PCs or Comrades) could ride in a Bike/Tauros/Chimera/Salamander, or be with some NPC infantry, for cover purposes. If you aren't playing Hogan's Operators, and have some other Classes, they might even be sensibly away, like a Master of Ordnance's Comrade (who rarely needs to be cringing out of cohesion for the important tricks, unlike other close-hugging Comrades), or a Sniper off in the boonies, watching for a tank-hunter, while the Sergeant moves with the Infantry protection unit.

true enough that mechanized infantry supporting a tank would be the most fun way to play, considering it involves combined arms warfare and offers more places for PCs to be involved

sadly this is not that fluffy since an armoured regiment is just that, armoured with support in the rear but not part of the fighting force (excluding regiments mixed due to loses and PDF forces of course)

i would actually take the mixed regiments rules from HotE if your players want to be infantry in support of tanks to give them a slight boost in aptitudes, talents and gear so they actually are abled to do anything useful and not just be operation human shield

Tanks need infantry support. Otherwise they're sitting ducks if anybody gets too close.

for reality that is true but in 40k the IG does things not because they are efficient but because it's tradition or law

anyways there have been tank battles in history with almost no infantry on the field, Kursk comes to mind

In the campaign I just finished a large part of it took place on one old, nearly broken down, leman russ. they didn't have access to another and there were 12 members of the squad (5 players with 7 comrades). they took it in shifts who sat on the top of the tank and who got to ride inside. they managed to use some extra webbing to make sure they could stay on top and not fall off. the players used this to take sleeping shifts to make sure they were well rested for most of this section.

for reality that is true but in 40k the IG does things not because they are efficient but because it's tradition or law

anyways there have been tank battles in history with almost no infantry on the field, Kursk comes to mind

But unless you are fighting SD forces in tanks, they will see your advantage (tanks), and run dudes up to blow them up. The IG DOES look at the expense and rarity of some things; it's why the IG doesn't get some of those things, and losing a Leman because you didn't send some very replaceable Infantry with it would get an Officer Commissared. Orks or DEs would easily ruin a tank, without some foot-slogging backup.

like i said it depends, kursk was fought on an open plain mostly

considering that a tanks weapon has 1km+ range they dont need infantry support there

also there are no such things as meltabombs in reality and even most infantry carried shaped charges dont do much to a mainbattletank, viceversa you dont need to nowerdays, missiles do the trick and are manportable

one of many reasons modern warfare goes away from MBTs and infantry and is heading towards mechanzied infantry

Soory, when I think of 40K, I more imagine WWII, or even Indiana Jones and the Last Crusade antics, where the tank has plenty o' range, and side guns to kill approachers, but if you get up there, you can really screw them over. Also, in reality, you'd lay tank traps, or land mines, which sort of are like those weapons, to the underside of a tank.

Of course, as in 40K, MPRs are a very effective way to go. That air power many people are hating creeping into the table top is also viable. Starcraft Siege Tanks are great, on paper, but a single flier gaks them, easily.

ironically that tank in last crusade was a WW1 tank

a WW2 tank with closed hatches cant be grenaded

tankmines work tough altough the ones that actually kill tanks are quite modern, in WW2 the usually just tracked the tank

hazaah for Immobilized result! (Sorry, the 40K TT talk escaped)

One more, just for you.

My first OW group had actually planned on something like this - we were running a "Hunter-Killer" regiment with an infantry squad riding on a Hellhound.

Well, we would've had that Hellhound if the dropship didn't blew up, so I never actually got to play that part. But it sounded cool in my head!

It even was a Valhallan regiment, too! Houseruled because there were no official rules yet.

Armor regiments... Almost always a bad idea

I think armored regiments warrant their own book, for this very reason. The Operator, Sergeant, and Heavy careers should have modified, comradless versions.

This is also why, when I ran my Only War campaign, that I disallowed the players from picking any kind of vehicle unit as the regiment type.

My players have never really evinced an interest in an armored regiment but I wouldn't see a problem in running it. Basically every three players (Or fraction thereof) equals one tank (typically Leman Russ but others are possible.). The biggest problem I see is that the players must basically all be operators in order for the game to work. This is also one of the only games that would routinely see the deployment of a specialist: An Admech engineseer (Who normally deploy at a rate of one per tank platoon.). The biggest challenge for this type of game is the roleplaying challenges. For Tankers; both in combat and out, their world revolves around their tank. It is their home, their transport, and their means of meeting the enemy! In combat, A tank allows it's crew to easily defeat enemies that would normally have them running for their lives! It's also sadly, often their coffin and final monument to their bravery! Their missions would typically involve being the "big hammer" of a given operation. Not a lot of room for investigation or mystery but with a little imagination, Anythings possible!

for reality that is true but in 40k the IG does things not because they are efficient but because it's tradition or law

anyways there have been tank battles in history with almost no infantry on the field, Kursk comes to mind

Kursk: Perhaps around 8000 armoured fighting vehicles of all types and ... some two million infantry.

The battle was a massive attrition fight where German armoured units tried to use their infantry to find gaps in the Soviet infantry lines, and the Soviets in turn sending armour to stop breakthroughs.

The only real tank battle as you seem to imagine was when the Germans tried to force the flank with tanks and was met by a defensive tank force rushed against them in the fighting around Prokhorovka. And even here its was not possible for armour to operate without their escorts.

A link to the order of battle on Wikipedia: http://en.wikipedia.org/wiki/Battle_of_Kursk_order_of_battle

While especially German panzergrenadier and some infantry divisions would contain tanks, it was mostly a infantry fight.

As for the plains being ... plain? Try seeing a Russian steppe. It appears flat from a distance, but on the ground it a mess of slopes to hide behind. Add to this the smoke and dust of moving columns and you get all the cover you need for effective infantry operations.