page_title: GT 101
section_title: Preliminary design
hierarchical_section_title: GT 101 / Preliminary design
caption_attribution_description: English: Berlin Gatow Luftwaffe museum
context_page_description: The GT 101 was a turboshaft-type gas turbine engine developed from the BMW 003 aviation engine, that was considered for installation in Nazi Germany's Panther tank. The German Army's development division, the Heereswaffenamt, studied a number of gas turbine engines for use in tanks starting in mid-1944. Although none of these was fitted operationally, the GT 101 reached a production quality stage of development. Several designs were produced over the lifetime of the program, including the GT 102 and GT 103.
context_section_description: Müller's first detailed design was a simple modification to a traditional jet engine, the core engine being based on the experimental Heinkel HeS 011, of which only 19 complete examples were ever built. In this design a separate turbine and power take-off shaft was bolted onto the exhaust of the engine core, the hot gases of the engine powering the turbine, and thus the tank. Since the engine core was entirely separate from the power take-off, torque was available immediately because the core could be left running at full speed while generating small amounts of power, the unneeded gases being "dumped". This design had a serious problem, however; when the load was removed, during gear shifts for instance, the power turbine was unloaded and could race out of control. Either the power turbine had to be braked during these periods, or the gas flow from the engine core had to be dumped.
  Another problem was that the Heereswaffenamt was seriously concerned about the quality of the fuels they could find. Unlike the aviation role where it was expected the fuel would be highly refined, it was considered likely the Army would end up with lower-quality fuels that could expected to contain all sorts of heavy contaminants. This led to the possibility that the fuel would not have time to mix properly in a traditional design, leading to poor combustion. They were particularly interested in having the fuel injectors rotate along with the engine core, which could be expected to lead to much better mixing, with the additional benefit of reducing hot spots on the turbine's stators. Unfortunately Müller's design did not appear to be able to be adapted to use these injectors, and the design was eventually rejected on 12 August 1944.
  Müller then turned to designs that removed the separate power turbine and instead required some sort of torque-maintaining transmission. The best solution to the problem would have been to drive an electrical generator and use the power to drive motors for traction (a system Porsche had tried to introduce several times), but a serious shortage of copper by this point in the war — as well as its relatively poor quality throughout the war for electrical use, from copper ore resources that Germany could access — ruled out this solution. Instead some sort of hydraulic transmission was to be used, although not initially specified. Additionally, the new design included the rotating fuel injectors in the combustion chamber that the Heereswaffenamt was interested in. Müller presented the new design on 14 September, and the Heereswaffenamt proved considerably more interested – the deteriorating fuel supply situation at this point may have been a factor as well.
  Oddly, they then suggested that any engine core developed for this role should also be suitable for aviation use, which led to the abandonment of the rotating injectors after all, and eventually to the use of a modified BMW 003 core, from a well-proven design. The basic layout had to be modified with the addition of a third bearing near the middle of the engine to help absorb shock loads, and a third turbine stage was added to the end of the engine to harness more torque. Unlike the earlier design, the power-take off could be placed anywhere (not just off the free turbine stage) and was in fact moved to the front of the engine in order to make the design as compatible as possible with existing engine compartments. The basic design was completed in mid-November, and assigned the name GT 101.
  Originally they had intended to mount the new engine in the Henschel-designed Tiger tank, but although the engine was smaller, in a diametral manner than the V-12 piston engine it replaced, its beginnings as the axial compressor-based BMW 003 aviation turbojet meant that it was too long to fit in the Tiger I's engine bay. Attention then turned to the Panther, which by this point in the war was to be the basis of all future tank production anyway (see the Entwicklung series for details). For experimental fitting, Porsche provided one of the prototype Jagdtiger hulls.
  Fitting of th
caption: A preserved BMW 003 aviation engine, the basis for the GT 101 turboshaft.
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