tigert
commented
9 years ago The thing with KAP140 altitude alerter is that it works even when the autopilot is not engaged, as long as the circuit breaker is on, and thus the unit gets power, and it can be used as a handy safeguard for keeping an eye on your altitude, because it will beep if you drift 200ft high or low. This is good and useful for cross country flying, but it can be disturbing when you do initial school flights or just want to fly around the airport or in the traffic pattern. And in this case it is disturbing for new Flightgear users in the to-be-default-aircraft since it just beeps and you don't know what is going on.
What usually happens in practice, is that for the flights when you do not use the autopilot or do not need the alerter, you just set the alerter to something like 5000 or 10000 feet so it is "out of the way" and never beeps in practice.
The manual (https://www.bendixking.com/HWL/media/PDF/PilotsGuides/PG-KAP140.pdf) does not make much comments about the persistence of the altitude preselect value, but I think it is persistent and survives through power off. A friend I asked also thinks this is the case.
Looks like the KAP140 logic is shared Nasal code in fgdata in Aircraft/Generic/kap140.nas,
and it is being used by a bunch of aircraft, which is a good thing. Looks like the altitude alert/preselect value is set through /autopilot/KAP140/settings/target-alt-ft but this seems
to be handled only one way (if you set it to 5000ft in properties, looks like the KAP140
user interface does not update to match, and it keeps its own internal state, and thus
the value gets set to whatever the KAP140 code has stored internally when you touch the
altitude knobs.
I think this needs to be dealt on the mailing list, as it is not exactly a c172p-detailed issue.
I think we need to do two things: first, make the setting persistent for each kap140-equipped aircraft, and make sure the initial first-time-ever value for the alerter is something like 5000 feet, so that it does not start beeping when you first try to get familiar with FlightGear and how to fly the aircraft. This change likely should be done in the KAP140 instrument itself, and thus not in C172P-detailed, or any other aircraft. The setting just needs to be exposed so that each aircraft can store its own persistent value.
(As a side thought, we should create most of the basic general aircraft instruments and avionics as shared like the KAP140, so making new aircraft would be simpler when you can just pick the common instruments and avionics from the shared set, and improvements to those would benefit everyone) - and your cockpit would be at least flyable without too much hassle with basic instrumentation.)
gilbertohasnofb
wkitty42
onox
The kap140 alt preselector is afaik set to 0ft by default. This has the side effect that when you pass 1000ft on takeoff ypu get the alert of leaving altitude (the beeper you wonder what the heck it is??) :)
We need to check the behavior of the kap140 in this case - my memory says it has a persistent memory and people usually set something like 10000ft there to keep it quiet for usual flights as most of the time the AP is off on training flights.
However I can check the manual for the correct behavior and will get back to this :)