Need help understanding what a switch does

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Jul 30, 2023
I noticed on the cockpit instrument panel of the JU87 that it has this dial: Fl.22405 Empfindlichkeitsregler, 1940 | Deutscheluftwaffe, but I'm not entirely sure what the numbers mean. I believe it's related to the turn indicator, so my assumption was it calibrates that, so if it was set to 5 for instance that the turn indicator arrow in the extreme left / right most position would mean you're turning at 5 degrees per second, or something like that.

Is that correct or is this doing something completely different?
The switch is to regulate the air pressure given from the engine pump or from a external nozzle to the pneumatic gyroscope (1) that worked with/in a turn (bank) indicator also called a turn and slip indicator or a rate-of-turn indicator. In other words it regulated the sensitivity of the system. Therefore the German name is tranlated as the sensitivity regulator.

the a turn and slip indicator ... Fl.22402 pneumatischer Wendezeiger, 1940



the pic source: Fl.22402 pneumatischer Wendezeiger, 1938 | Deutscheluftwaffe

and the nozzle ..

the source: Fl.23401 Förderdüse für Kreiselgeräte | Deutscheluftwaffe
Thanks for the response! Do you know what the significance of the numbers are? From your description it sounds like some indicator of sensitivity is it as simple as degrees per second for when the needle is in the fully left or fully right position or something else?. Unfortunately my German isn't enough to read the document you posted so I'm not sure if it's covered there.
The background to this is I'm very slowly trying to model the JU87 in Microsoft Flight Simulator, I have the turn and slip indicator working so I'd like to get this switch to change the behaviour of that gauge if possible.
Actually I don't have more details on that. But the Fl.22405 device is just a pressure regulator. Its settings cause the air pressure going to the gyroscope either higher or low. Because the pressure depended on the speed of the aircraft or the pump engine RPM it might cause the gyroscope going too fast or too slow at the different phases of flight. And this could affect the gyroscopic moment. As a result the indicator might react to the pressure chagings incorrectly giving the wrong indications. Certainly I may be wrong.
IMHO more info should be in the flight manual. Additionally I have seen the switch on the pilot panel of the early Ju-87, I mean the A to B-1/R-1 variant. It seems that beginning the B-2 it was replaced by the electrical indicator.
ah, that's interesting, I hadn't thought about it like that. I have the manual for the B-2 variant although as you mentioned it doesn't have this, I'll have to do a bit more digging and see if I can find the B-1 manual.
IMHO the switch and the indicator could also be mounted for the early B-2. Perhaps the Pilot's Notes could be helpful as well. Anyway I have seen the turn and slip indicator in various German training planes. However the switch can't be found there. So I guess the way the air pressure was provided to the gyro and its value didn't require the switch if the aircraft was slow.
Very long ago I worked on some vacuum gyros and these had speed regulation devices such as small air brakes on springs such that at at least an overspeed condition the gyro wheel would avoid overspeed. From even older physics, I think that a gyro wheel will always want to stay in its plane of rotation and speed will alter the resistance to change so indeed the force against a spring will vary by gyro speed but varying air pressure would need to be at precise values to convert to a wheel speed. What's my point? I think all I can say is we want more details to analyze.

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