About this detail of the Tiger
The Tiger's HL210 engine had two exhaust pipes, and they exited the hull through holes in the lower rear plate. Mufflers were provided to reduce engine noise; they took the form of sheet-metal cylinders outside the hull.
This diagram shows a profile of a muffler and the rear of the hull, seen from the side. The exhaust pipe enters the muffler near its bottom, and gases are expelled at the top. The mufflers had internal baffles [1, see 3.1.1] ; but I have no information about them.
Because the Tiger was capable of driving while submerged, a non-return valve was built into the top of each muffler as shown here. This consisted of a hinged flapper, 90mm in diameter. While underwater, the flapper was alternately opened by escaping gases and closed by water pressure.
In normal operation, the flap was held open by a pin pushed through holes in the hinge and the end of its arm. The pin was attached to one of the 5 bolts by a chain.
Photographs show that the flappers could be aligned on the hull in any one of these three alignments. I don't yet know whether these were randomly assigned or can be tied to manufacturing date. In every photograph that I have seen, one of the bolt heads is central at the rear.
Such was the power of the engine that flames were emitted from the top of the mufflers. The 502nd heavy tank battalion, operating near Leningrad in the winter of 1942, found that the enemy could see these and identify the Tigers too easily. They therefore attached extension pipes of various lengths and diameters to the tops of their tanks' mufflers. One example is shown here; it had slots cut into the sides to provide a draft.
This extension pipe, a full 500mm long, was used on the well-known Tiger "100" and at least one other tank.
In January 1943, starting on hull 250082 [1, see 3.4.1.14] , a solution to this problem was built into new Tigers. Sheet-metal guards were added to the hull surrounding each muffler, so that they would not be visible when glowing in the dark. A baffle plate was added to the top to deflect the flames sideways into the guard. This diagram shows the top of the muffler; the guard plate is supported on five posts using the old bolt positions. The chain of the locking pin was now attached to the base of the valve hinge [2] .
This is the top of the baffle plate, which was 10mm thick and 250mm wide (slightly wider than the muffler cylinders).
In September 1943, the submersion ability of the Tiger was dropped. Mufflers were built without the flapper valve, as shown here. The diagram also shows the top of the muffler cylinder, which now had a 80mm hole in a plain flat plate.
Of the Tiger hulls surviving in museums, only the Sturmtiger in Kubinka still has its original flapper valves. I have no data from that tank, therefore my diagrams are somewhat crude.
[1] DW to Tiger 1