Power Levers and Fuel-Trim switches
Quote from yours truly, above:
So, on the Dart, the pilot has no control over engine rpm at a particular throttle setting - some widget decides it for him.
[Unquote]
Must admit to having misgivings about the above, while out for dinner.
1) "Throttle" is the wrong term; the pilot controls each engine with what is called a Power Lever.
2) I got the cart before the horse. Once the engine power is increased sufficiently for T/O, and the propeller comes out of ground-fine pitch, the Power Lever is effectively an engine rpm selector. The "widget" (CASC unit?) has to decide the fuel flow appropriate for the rpm chosen. That delivered, the exact rpm is achieved by the blade-pitch adjustment of the Rotol propeller constant-speed unit. [The achieved engine torque is monitored, and if it falls below a certain low figure at take-off power, the propeller will auto-feather.]
3) The fuel-flow schedule, at a given rpm, can be modified by the crew. This is achieved by the fuel-trim switches, on a scale of 0 - 100. A fuel-trim figure for take-off is calculated and set in advance, according to the conditions. After take-off and during clean-up, the fuel trim is reduced (I think). At top of descent, it is reduced to zero, and descent rpm is set with the power lever. On the initial approach, fuel trim is increased, perhaps to 50. On finals, probably with the landing gear, it is increased to max (100), in preparation for a possible go-around.
If you get it right, the power levers (and, therefore, engine rpm) can remain untouched from TOD until the flare.
Does this sound familiar to you ex-Dart pilots? dxi188, does any of the above make sense?