The German Army needed vehicles to train tank crew drivers but the big problem was fuel. Diesel and gasoline (petrol) was required for front line vehicles and there was a massive shortage with no solution in sight. German engineers looked for an alternative fuel source. They came up with two solutions. One was a device that burnt wood and produced combustible gas that could power an engine. The other was to use compressed gas bottles that contained gas similar to that supplied to homes in Germany for cooking.
These vehicles were called “Fahrschulwanne”. This is a term used by those who were trained on these vehicles and a combination of “Fahrschule” (Driving school) and the German term “Wanne”. This does not mean the lower hull of a tank but is malapropism (the mistaken use of a word in place of a similar-sounding one, often with an amusing effect) of the term “Badewanne” (Bathtub).
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It is a German Army tradition to use nicknames or funny designations for any kind of vehicle. The modern German Army still does this. It calls their Amphibious-Company M3 Amphibious Rigs “Wasser-Bus”, which means water-bus. The term ‘Fahrschulpanzer’ translates to ‘Driving School Tank’. Fahrschulepanzerjäger means Tank-Destroyer-Training-school-vehicle.
A number of books and websites have miss-identified these vehicles as battlefield smoke generators because of the similarity to the Allied smoke generators.
Wood Gas powered tanks – Holzgas
The commercial term for a wood gas generator, or Holzkohevergaser in German, was the Imbert-holz-gas system which then was shortened to Holzgas. The gas was used to fuel vehicle engines thus saving on petrol/gasoline and diesel. The Imbert system is a closed external combustion system designed to produce gas that can be cooled and used in an internal combustion engine.
The Imbert system uses wood pellets and the gas produced needs cleaning and cooling prior to passing to the cylinders of the vehicle, otherwise it would choke up with residue. During the production process, biomass or other carbon-containing materials are gasified within the oxygen-limited closed environment of a wood gas generator to produce hydrogen and carbon monoxide.
These gases can then be burnt as a fuel within an oxygen rich environment to produce carbon dioxide, water and heat. In Germany, around 500,000 gas powered vehicles were in use at the end of the war due to the lack of petroleum.
Holzgas wood gas burner diagram
Town Gas powered tanks – Stadtgas
As WWII progressed, gasoline / petrol and diesel became increasingly scarce in Germany. In order to save precious fuel, the Panzer driving schools (Panzer Fahrschule) frequently used vehicles equipped with Stadtgas (city gas) in the form of LPG compressed gas bottles fixed to the outside of the tank chassis for safety reasons. A German fuel shortage in World War 2, caused largely by Germany’s small natural oil reserves, was a factor in the German defeat. The Allied bombing program also depleted urgently needed stocks of fuel.
Prior to WW2 Germany, was heavily dependent on foreign fuel imports. It consumed 44.6 million barrels of oil annually and only produced 12.8 million barrels of domestic oil and synthetic oil. Germany did have a large deposit of coal and lignite which enabled them to increase the amount of synthetic fuel produced but it was never enough. This was one of the reasons Hitler decided to open up the Eastern front, in order to capture oil production plants.
German towns used coal gas sometimes called town gas or Stadtgas for heating, lighting and cooking. It was made by blowing air through an incandescent fuel bed (commonly coke or coal) in a gas producer. The reaction of fuel with insufficient air for total combustion produces carbon monoxide (CO); this reaction is exothermic and self-sustaining. It was discovered that adding steam to the input air of a gas producer would increase the calorific value of the fuel gas by enriching it with CO and hydrogen (H2) produced by water gas reactions.
Luckily, Town gas or Stadtgas can be bottled. When mildly compressed it easily changes to a liquid state. This allows a large amount of gas (stored energy) to be contained in a relatively small space. The reverse process is just as fortunate – if decompressed (allowed to escape the pressure vessel) the liquid gas will quickly revert to its gaseous state (vaporize).
One of the first tanks to be used as a turretless driving school vehicle was the Panzer I. At first, the fuel shortage problems had not been realized, and these vehicles did not need Holzgas or Stadtgas. The tank school was still using petrol to fuel their vehicles. This soon changed and they were quickly converted. Some were powered by a Holzgas wood burner and others by compressed Stadtgas in high-pressure bottles.
The first Panzer I batches were delivered without superstructure or turret, to be used as driver training vehicles.
These vehicles were named Fahrschulepanzerwagen I Ausf.A
Another image of a Fahrschulepanzerwagen I Ausf.A, at work in a winter scenery.
A group of Fahrschulepanzerwagen I Ausf.As fording a shallow lake or river.
A Fahrschulepanzerwagen I Ausf.B with what looks like a Stadgas generator.
A Fahrschulepanzerwagen I Ausf.A with an experimental Festbettvergaser Holzgas generator
The rear of a Fahrschulepanzerwagen I with Holzgas generator
Several Holzgas Fahrschulpanzer Is were modified to resemble tanks and used to train the Volkssturm in 1945.
This Panzer I Ausf. A chassis is powered by a wood gas burner and is fitted with a Panzer III turret. It was used for turret crew training.
German tank school wood gas powered Fahrschulpanzer I Ausf.A chassis and a Panzer III turret armed with 3.7 cm (1.46 in) gun used for teaching three-man turret crew procedures.
After the invasion of France in May 1940, the Panzer II light tank was considered obsolete and was withdrawn from front line service. Some were issued to Panzer schools. Some were also fitted with a tall wood burning gasifier combustion chamber of the Holzgas system standing erect, fixed to the rear of the tank. The long tubes were used to store and cool the gas down before it was piped into the engine.
Fahrschulepanzerwagen II with Imbert Holzvergasser wood gas burner with tanks from Pz.Abt 202, at Sentvid, Medvode near Ljubljana, Yugoslavia
A Fahrschulepanzerwagen II being transported by rail, next to an Italian M15/42 with an added rear bustle.
Another Fahrschulepanzerwagen II. These photographs were taken in 1945 Yugoslavia and had been captured by Soviet forces along with some Italian tanks.
Another view of the same Fahrschulepanzerwagen II.
The Panzer III tank was the main battle tank of the German army from mid-1940 to 1943. Tank crews needed to be trained on that vehicle type. They could not be expected to learn how to drive a tank in a light tank, like a Panzer I or Panzer II, and directly master a much heavier and bigger machine.
Special versions of the Panzer III tank were built without a turret. They had a large open central area which held the students and the instructor.
This Fahrschulpanzer III was powered by gasoline (petrol). This photo was taken early on in the war.
Notice that there are only five track road wheels on this Fahrschulepanzerwagen III, and not the normal six wheels. This tank is a rare example of a Panzer III Ausf.A, the first version of the Panzer III that entered service with the German Army. They were first delivered in 1937. The wheels are bigger than the wheels used in later versions.
This Fahrschulpanzer III was converted to run on compressed Stadgas. Four large gas bottles were strapped to the top of the track guard, two on each side.
The Panzer IV tank chassis was also used for tank driver training. Some had the turret removed and Stadtgas bottles fitted at the rear of the vehicle. A special boxed container was mounted in a frame at the end of the engine compartment. The gas cylinders were placed vertically inside the box.
A good side view of a Fahrschulepanzer IV and its Stadtgas cylinders.
The front part of the Stadgas cylinder holder. Some piping can be seen, which probably took the gas from the containers to the engine.
A better view of the cylinders from the rear.
A turreted Panzer IV with the gas cylinders fixed in a horizontal position on the outside of the tank at the rear.
Another turreted Panzer IV, but with the gas cylinders fixed vertically at the rear. Also, notice the full Schurzens.
Fahrschulpanzer I, petrol powered
Fahrschulpanzer I petrol powered tank with raised rear for students
Fahrschulpanzer I Holzgas with a mock-up turret. It was meant to simulate an enemy tank during the training of Volkssturm troops
Fahrschulpanzer II Holzgas
Fahrschulpanzer Sd.Kfz.251/1 Ausf.C
Sd.Kfz.251/1 Red Cross ambulance powered by Stadtgas
Fahrschulpanzer V Panther
The Fahrschule Panther used six Stadtgas bottles, three on each side, in brackets attached to a platform. A system of conduits and nozzles ran over the engine deck to connect the bottles to the Panther’s fuel system. Because of the obvious safety risks vehicles with Stadtgas were only used for training and didn’t see combat.
Stadtgas Fahrschulepanzerwagen V Panther Ausf.D with its crew in front of it
Another photo of a Fahrschulepanzerwagen V Panther powered by Stadtgas cylinders. The image is obviously overexposed.
Fahrschulepanzerwagen V Panther powered by Stadtgas cylinders. Notice that the hull machine-gun flap is closed.
Fahrschulpanzer VI Tiger
Many people may be shocked to discover that the feared German Army Tiger tank was also modified to run on cooking gas and wood gas. They were not used in combat on the front line. They were used as Fahrschulpanzer Tiger tanks (driving school Tiger tanks). The first photograph shows
A Tiger tank chassis converted to run on the Holzgas system. The wood burner combustion unit is in the middle at the rear and it is flanked on each side by the vertical gas storage and cooling cylinders.
Tiger tanks that were converted to be powered by Stadtgas. The four compressed gas cylinders were fixed to the rear of the vehicle, two on each side.
Notice that the cylinder mounting is different from the previous photograph. That had the top of the gas cylinder pointing towards the front of the vehicle at a downwards angle, while this vehicle other has it pointing to the rear of the tank.
Fahrschulepanzerwagen VI Tiger tank with mechanical problems. The Stadtgas cylinders can be seen at the back.
This photo shows the way the Stadtgas cylinders were fitted at the rear of the tank school Tigers.
Stadtgas powered German tank school Tiger on parade. The gas cylinders are at the back.
German tank driving school lesson gone wrong – Credits: Micro antic
Stadtgas powered German tank school Tiger on heathland. The gas cylinders are at the back.
Fahrschulpanzer Beutepanzer M14/41
Turretless Beutepanzer captured Italian M14/41 tank powered by Holzgas used to train drivers. It has a Balkenkreuz cross on the superstructure. It could be a Semovente M42 75/18 SPG. It is hard to tell as they use the same chassis.
Fahrschulpanzer Marder III
Self-propelled anti-tank gun crews also had to learn how to drive their vehicles. This is a photograph of a Marder III Ausf.M converted into a Fahrschulpanzer Marder III tank driving school vehicle. As the vehicle was smaller than the tank chassis used in driver training, only two gas cylinders could be fitted to the outside on the Marder III.
Fahrschulepanzerjäger 38(t) Ausf.M Marder III Holzgasantrieb
The Czechoslovakian built Panzer 38(t) tank chassis was used as a basis to manufacture tank hunters like the Hetzer and self-propelled anti-tank and artillery guns. It was also used to make wood gas powered German tank driving school vehicles.
The tall towers fixed to the rear of the vehicle are the wood burning gasifier Holzgas combustion unit. It was an airtight vessel into which was introduced a charge of wood, charcoal, or anthracite coal. The fuel was heated either internally or externally in order to initiate a self-sustaining gasification of the fuel in an oxygen deprived environment.
The precipitation tank is on the side, behind the three long gas cooling and storage pipes affixed to both sides of the tank chassis.
Four Fahrschulpanzer 38(t) vehicles in a line in a post-WW2 scrap yard, waiting to be cut up.
Fahrschulpanzer Sd.Kfz.251/1 Halftrack
German military driving schools also converted Sd.Kfz.251 half tracks to run on wood gas Holzgas burners as well as compressed Stadtgas. The half-tracks that were fitted with a wood burner, like in the first photograph below, had the gas from the burner piped into the reservoir, and then into the modified engine carburetor. Wood-gas modified vehicles were therefore technically a dual fuel vehicle. The self-sustaining gasification of the wood charcoal or coal required another fuel to start the process.
Gas reservoir sizes depended upon the vehicle, engine, and gasifier size. The gas storage containers were smaller on the half-tracks, as they had an engine with a better fuel consumption rate compared with the very thirst tank engines. In the case of small engines, like on the Kubelwagen car, the wood gas was piped directly into the modified engine carburetor.
Sd.Kfz.250/1 Ausf.A leichter Schützenpanzerwagen (Holzgas)
You can see the Holzgas wood burner on the back of this half-track
Schützenpanzerwagen Sd.Kfz.251/1 Ausf.B Stadtgas
This Stadtgas powered half-track has been used as a battlefield ambulance.
This wood gas powered German half-track has a lower profile burner at the back.
German Supply vehicles
Many German supply vehicles that operated behind the front-line were fitted with wood gas Holzgas burners because of fuel shortages.