While the US in WWII had to rely on just dropping troops out of a plane, the Empire of Man has a bit of extra technological advantage in order to land squads of marines. That comes in the form of the Sokar Pattern Stormbird. They'll get your Marines to the battlefield in style and with some pretty heavy support going on.
How large is this vehicle (it's hard to really call it a "miniature" at this point)? Well, the thing weighs 6kg. From nose tip to tail, it's a half-meter. You can fit an entire Deimos pattern Rhino in the back. In the game, it can hold 50 Marines (and I wouldn't be surprised if you could actually fit 50 of the dudes in there).
There's also two bundles you can get with the Stormbird. You can get it with a set of Betrayal at Calth, or you can get it with an Imperialis Landing Pad terrain piece.