Already since its conception, the exhaust system of the Panther had been kind of troublesome. During the Panther’s production various solutions have been proposed and fitted. In this post I’ll elaborate a bit on two of these solutions in particular.
Auspufftopf – Exhaust muffler
It is often disregarded or simply not known that the well known exhaust pipes with a slight curved section are not part of the Panther’s original design. The original exhaust system featured a muffler to reduce engine noise. The muffler was mounted horizontally between the storage bins at the vehicle’s rear. On top of the muffler there is a single exhaust pipe through which exhaust fumes leave the muffler. The muffler can be seen on the initial construction drawing by M·A·N dating back to 2 May 1942 as was also mounted to the second prototype, Versuchspanther v2. To allow for deep wading the muffler would additionally be fitted with a one-way valve to prevent water from entering1
The same exhaust system was scheduled for series production and is visible in the original design drawings for the Ausf. D . The muffler was, however, dropped from production very early on. Already on 11 February 1943 M·A·N noted that that the muffler led to high temperatures in the engine compartment that caused fuel to evaporate (fuel evaporating outside the carburettors is not only a waste of resources, but can also cause engine fires due to untimely ignition). It was clear that something was to be done to remedy the overheating problem. Not much later on 25 February M·A·N reported that simply removing the muffler alleviated the problem without any noticeable drawbacks. The Eberspächer firm was subsequently ordered to design a Flammenvernichter. 
The fourth production Panther had been confiscated by Wa Prüf 6 for the purpose of running in-depth trials. It arrived at Verskraft Kummersdorf in February ,  were it, among others, underwent trials with an alternative, larger muffler to reduce heat build-up. Various combinations of exhaust systems were trialled too: original muffler, alternative muffler design and one with Flammenvernichter. After the trials completed the Panther was refitted with two curved exhaust pipes by M·A·N on 28 March .
Due to the lack of photographic evidence it is hard to tell on what scale the muffler was actually installed. It is clear that a muffler was at least installed on Fgst.Nr. 210004 as part of trials. There are no photos of Panthers belonging to Panzer Regiment 39 in Kursk that show the muffler. It is safe to assume no Panthers have entered combat with the muffler fitted. An order by Wa Prüf 6 dating from March 1943 seems to suggest at least a small amount of Panthers initially had the muffler installed. The order contains a list of deficiencies to be corrected during the rebuild programme conducted at Berlin-Falkensee by Demag. This large rebuild operation was to take place starting in April 1943 and, among others, required to “[r]emove the exhaust mufflers and install curved sections of pipe”2 .
Based on the timing of events I would argue that at least some of the 13 Panthers that took part in a large demonstration for Speer at Grafenwöhr on 21 February were fitted with the old muffler design. Unfortunately, the quality of the photo depicting this demonstration leaves to be desired and does not show any clear details on the exhaust system.
Substantiating the limited installation of the muffler is an interview with Werner Kriegel who served in Panzer Abteilung 51. Kriegel recalls training on the first Panthers at Grafenwöhr starting in March 1943. He continues to explain how the Fahrschule Panther they learned to drive with were distinctly different from the Panthers they were issued with: “All vehicles were prepared for deep wading/diving. Externally, a large horizontal exhaust with a snorkel valve was fitted at the rear plate.”  The overall trustworthiness of this recollection must perhaps not be overstated. There are incoherencies and the information might have been infused with (incorrect) post-war knowledge3.
A feature reminiscent of the original mounting bracket for the horizontal exhaust muffler apparently has survived. Two seemingly unused threaded bolts persisted in the Panther’s hull design until the introduction of the entzwickelte Wanne for the Ausf. G. Original design drawing presumably show these threaded bolts being used to fasten the exhaust muffler using a bracket. After the muffler was dropped, only the top two threaded bolts would be used by a bracket holding the two curved exhaust pipes in place.
As already mentioned above, various combinations for the exhaust system were trialled in early 1943. Among these systems was a flame suppressing solution by the firm Eberspächer . The Eberspächer had first acquired experience with flame damping exhaust solutions when they were contracted to create such dampers for Luftwaffe air frames . After the Luftwaffe’s increasing losses during day-time raids they increasingly resorted to night time operations. The relative protection from the darkness was, however, quickly lost when British fighters closed the technology gap which allowed them to also fly at night. The British planes appeared almost invisible to the German bomber and fighter crews as they employed flame dampers. In response, the Luftwaffe requested a similar solution to be created as soon as possible. 
Flame damping exhausts were actually installed only much later on production Panthers. M.N.H was the first assembly plant which began mounting the so called Flammenvernichtern, which roughly translates to “flame eliminators”, in December 1944 . Visual signs coming from the exhaust could give away the position of a tank not only in night combat, but also made any overnight unit movements easily detectable. In a short survey of the Panther tank by the US army, General White explicitly mentions the glowing exhaust pipes as a weakness. After two weeks of trials with the Panther tank, White writes: “The weaknesses of the Mark V in comparison with the M4A3E8 are believed to be as follows: (…) d. Bright glow of the exhaust stacks at night after the engine runs for short period.” 
Early Ausf. G Panthers sported sheet metal covers to partially hide the red hot exhaust pipes. The flame eliminators provided a more permanent solution to hide the exhaust pipes from view. Additionally, like their name suggests, they hide (engine) flames sprouting from the exhaust – also known as after fires. A video taken in 2008 of the first engine run for Jacque Littlefield’s Panther4 shows the visibility of the engine flames nicely.
Although I have no definite source ascribing the Panther’s final Flammenvernichteranlage (FlaV Anlage – flame eliminator system) to the Eberspächer firm, the design is reminiscent of that developed by the same firm for nightfighters . It combines features of the Flammenvernichter for the Bf 110 G-4 and He 177.
The system on the Panther is comprised of three main parts:
(1) a mixing tube (Mischrohr) of ~200 mm in diameter where air and exhaust gasses are mixed.
(2) A circular nozzle (Ringdüse) in the tube allows exhaust gasses to enter the mixing tube and projects them upwards into the tube. The ring design allows cool air to easily enter the tube.
(3) The tube is closed of by an anti-glare grating (Blendgitter) with 28 slats. The grating reminds of a fan, but the contraption is completely static. The slats are chevron shaped and as such hide any flames in the tube from view – no matter the viewing angle. The four bolts on each side of the tube allow the fitting of a curved hood (Absatzkrümmer) to redirect the exhaust gasses coming from the tube.
A flawed design?
It is apparent that many components of the FlaV on the Panther have been taken from a similar design for use on aircraft. A good example of a component which seem to have been recycled from an aircraft version of the FlaV is the cone in the middle of the grating. Its aerodynamic shape makes no sense on the Panther, but it does all the more when imagining the system mounted to an aircraft engine facing the airflow head-on. Additionally, the design of the circular nozzle in the tube allows an uninterrupted airflow to take place. This airflow should carry the exhaust fumes out of the tube. Again, on the Panther this feature does not come to justice: there is no airflow from underneath the FlaV to carry away the fumes.
Altogether the design achieves its goal of damping flames, but seems flawed. Period photographs show signs of heat build-up in the upper part of the tube. The lack of a strong airflow from beneath the exhaust causes a build up of heath underneath the grating. The resulting thermal load on the tube makes the paint discolour.