Hi, Been working on and off with Tristar's new Pz. IV kit and I see there is what I take to be a door or hatch opening on the turret's roof right in from the the commader's cupola. (Part B29 if you're familiar with this kit.) Would I be correct in assuming that this was some type of vent for the gun smoke to go out of during combat operations? And if so, would it be correct to give this area a dusting of black pigment to represent this fume residue? This is the only thing I can think this hatch's function would be. Just wondering here.

Thanks and take care, Sgirty

You are correct it is a signal port. Could be flares could be flags. I think you would have to fire alot of flares to blacken the area though.

According to the Squadron - PzKpfw IV in action, this is "rectangualar ventilation flap in the roof in front of the cupola allowed for exchange of fresh air."
It also goes on to say that there was an armoured outlet cowl on the forward left side of the hull. So I guess no fume stains.
The two cone shape items on each side of it are right and left covered signal ports, used to shield signal lamps. The right side one was eliminated for the E version. The left side eliminated for the H version.

In the E version this rectangular vent flap was discarded in favour of a raised circular housing for an eletrical fan.
Some info from a worthwhile little book.

If its a rectangular shaped hatch, it is indeed for venting propellent fumes from the turret.

Chris "toadman" Hughes
Toadman's Tank Pictures