Kommandogerat, or air-operated automatic transmission
The gloomy German genius invented absolutely hellish designs. The scheme is average, because there are a lot of variations. They take a piston engine, it is not controlled directly, primitively – this is not about the Germans. They take a cuckoo clock and hang it behind the engine. They connect to it the control of the gas, revolutions, angle of the propeller blades, fuel mixture, ignition angle, speed of rotation of the supercharger, fill it with motor oil for lubrication and cooling. All this is shoved into a single-engine fighter. From the resulting devil-box, a lonely gas handle is brought out into the cockpit, with which the pilots immediately begin to scrape back and forth, muttering in a half-whisper “ZER GUT!”. At the same time, sweat appears on the foreheads of field aircraft mechanics. The Germans from BMW kindly offered their wonder weapon (mainly in the form of trophies), but everyone refused, including other Germans.
But why?
First, let's figure out how to control a piston aircraft engine from the Second World War. Imagine that you need to overtake on the highway with the maximum acceleration possible for the car. If you have an automatic transmission, then everything is simple: pedal to the floor, and the gearbox-engine brains themselves will downshift (or even two), open the air damper and start pouring buckets of fuel into the engine. The same maneuver with a manual transmission will require a small but clear sequence of actions from the driver. If this happens in the air, then for maximum power you also need to monitor the fuel mixture, because with altitude there is less air. To do this, you can reduce the fuel supply and / or inflate more air from the atmosphere (supercharger). But what if in the process you also need to turn your head and the steering wheel to dodge a rapidly approaching car from behind? And what if this car is shooting at you?
A typical set of engine controls looks something like this:
– boost lever (gas)
– propeller pitch lever (analogous to a gearbox)
– mixture lever (height corrector)
– supercharger speed lever (if you go too high)
– engine cooling flaps
– oil cooling flaps
Not enough? Here's more. American heavy twin-engine night fighter P-61 “Black Widow” – early versions have 13 engine controls:
– 2 boost levers
– 2 step levers
– 2 mixture levers
– 2 supercharger levers
– 3 levers for positioning the engine cooling flaps
– 2 intercooler flaps position levers (cools the air pumped into the engine)
Have you imagined the pilot's face? To be fair, the Americans also realized that this was too much and on later modifications they replaced the wing levers with “open/close/auto” switches.
And these controls are not always conveniently located. For example, on the Yak-1, the controls for the oil and engine cooling flaps are located to the right of the pilot. To control them, you need to use your right hand, which the pilot uses to control the plane, leaving the engine controls. All this is controlled by one person, who, in fact, has other things to do besides the engine. Especially a fighter pilot. Our analogy with overtaking on the fingers shows how a pilot switches from maximum economy mode to maximum power mode. To do this, he needs to quickly and CONSISTENTLY:
1) make the fuel mixture (M) fatter (it was strangled for the sake of economy)
2) set the propeller (P) to a small angle (large angle – economy, small angle – it is easier for the engine to turn)
3) give gas (big lever)
3.1) open all cooling (not necessarily at once)
Under attack, in a hurry and blindly, you can mix up and break the engine. Forgot about the mixture – not enough power, overheating, died. Shoved the rev lever forward too quickly – exceeded the permissible revs, jammed, died. Forgot about the cooling flaps – overheating, died.
Any properly functioning automatic system gave the pilot an advantage in reaction time and the optimum characteristics that could be squeezed out of the engine. For example, the early Spitfires of the Battle of Britain were faster on paper than the Messerschmitt 109, but to achieve the true maximum speed, it was necessary to manually select the optimum mixture for each specific altitude, for which there is not always time in a real air battle. The same was true for most Soviet aircraft. However, the early 109s also distinguished themselves by manually setting the propeller pitch (the angle of the propeller blades), which is a much bigger headache than the lack of an automatic mixture control.
The Germans at BMW went further and made a kommandogerat (command device), the grandfather of modern electronic brains for engines. This mechanical computer read the throttle angle in the cockpit, engine speed, air pressure and temperature at the engine inlet, and based on this data, automatically set the fuel mixture, propeller blade angle, boost pressure, ignition angle and supercharger speed depending on the flight altitude. Instead of constantly calculating and adjusting, the pilot could fully concentrate on flying without sacrificing horsepower. In case of damage to the control unit, an emergency mode was provided, allowing you to reach the airfield.
If it's so great, why hasn't anyone else used it?
Objectively, this is an expensive and technically complex device. Judging by the lack of widespread complaints from pilots and technicians, the device was quite reliable. However, it is still a metal devil-clock with a cuckoo clock half the size of an engine and the corresponding weight. The manual for field mechanics generally explained how to remove it, install it, connect it to the aircraft systems and how to fix minor faults. In the case of non-minor faults, the control unit was removed and sent to the factory as a whole. Let me remind you that the engines themselves could be repaired in field workshops within reasonable limits.
A “cheap” analogue is a cool head and fast hands of the pilot (and without excess weight). On single-seat aircraft, after bringing the engine to combat mode (maximum power), the kommandogerat did not provide any tangible advantages: the required power in combat is regulated only by the throttle lever (the Soviets also have a mixture, but not so much). On aircraft with more than one pilot, fine-tuning of the engine operating modes and related systems was done by one of the pilots, or even a separate crew member – the flight engineer. Nevertheless, the kommandogerat turned out to be very useful to the Germans when the overall level of training of German pilots began to sag, and not only everyone knew how to quickly pull a bunch of handles in the cockpit.
After the war, the jet era began, which was much simpler for the pilot in terms of engine control. A jet engine is essentially an open pipe with a fuel hose inserted into it, which the pilot controls with a single throttle lever. However, with the development of electronics, the control principle came to the automotive industry in the form of an ECU (electronic control unit) and now every modern car carries its own small, but very self-confident KOMMANDOGERAT.
Author: Fuzelash Striped
