About this detail of the Tiger
On each side of the Tiger 1 is a vertical radiator, through which air passes from front to rear. There are 4 heavy metal grilles lying horizontally on the hull top, serving as air inlets and outlets for these radiators. It is not widely known that the forward grilles have ducts welded underneath them. These ducts, made of 8mm armour plate, serve to protect the upper fuel tanks lying under the grilles; indeed it is impossible to see the fuel tanks by looking through the grilles.
I know of only 4 photographs in published books and magazines that show this duct. In Jean-Charles Breucque's site you can see a grille and its duct rusting away at Saumur Museum.
The model above shows a complete duct, with the grille on top made transparent. At the rear of the duct, closest to you, there is a strut that prevents the weight of the grille from collapsing the duct if it is laid on the ground. At the front, there is a chimney for the inlet of the fuel tank. The bottom of the duct has two wide notches, making room for the feet of the radiator.
Seen from below, the duct is very simple. I have coloured this model to represent primer paint. I haven't yet filled weld in the edges of the plates.
One of the two lower corners of the duct has a notch cut out from it and a welded cover piece, as you can see above. This is to make room for the fuel lead which enters the radiator compartment at that point. Therefore, the left-hand duct is not interchangeable with the right-hand duct. The heavy cast grilles atop them are also different.
This diagram shows the plan of the duct seen from below. Dimensions are obtained by measuring an actual vehicle.
This profile shows the duct and the grille. The duct extends 500mm below the grille base, which is itself 85mm below the top surface of the hull.
This section shows where the supporting strut lies in the duct and how the grille has a rear lip for supporting the radiator cover plate behind it.
Finally, this is the duct seen from behind. Notice that the left and right sides of the grille are not the same. In the final-model Tigers, a wooden panel for catching splinters was installed within this duct.
[1] Survey of vehicle 251114, at Saumur, by Jean-Charles Breucque
[2] DW to Tiger 1