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HHS81 / c182s

Cessna C182S (1996 model) for FlightGear
GNU General Public License v2.0
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Electrical bus system fixes and code tidying #565

Closed hbeni closed 6 months ago

hbeni commented 7 months ago

While looking at #564, I found alot of not correct wirings. Also the code really needs a cleanup - its bad formatted and thus hard to maintain.

C182T should also be reviewed.

hbeni commented 7 months ago

Shift click could operate both switches at once. Or maybe do it as default and make shift operate a single switch?

grafik

EDIT: We should ammend the tooltip to indicate modes of operation. But it looks sensible to me that as long as both switches are in the same position, they should be switched together (so ON/OFF for both switches, unless one presses "shift" to switch individually)

EDIT2: The avionics switch is clearly separated in the POH.

hbeni commented 7 months ago

For the Archives; regardind the GPU (ground power unit) I had a mail discussion with David Megginson to clarify, wether the GPU supplies power to the bus with the master-bat switch in the OFF position (like it is modelled now).

I believe that to be wrong, and found evidence.

So, I did dig into the matter more and found this discussion: https://aviation.stackexchange.com/questions/72425/how-does-the-battery-master-switch-activate-the-battery-contactor-in-cessna-152

It means that this is really depending on plane, like you said.

C182S For the C182s, I looked closer to the schematics (POH 7-30, attached). There, we have a dedicated "external power relay", that is linked to the master switch. It also is linked to the battery. The POH stats that the "master BAT switch controlls all electrical power to the plane", and also "The primary buses are on anytime the master switch is turned on, and are not affected by starter or external power usage. The avionics buses are on when the master switch and avionics master switch are in the ON position.". For the case that the battery is dead,and therefore can not provide current via the master switch to ground, so the contactor closes, the external power does close the battery contactor too. But since the external power relay is placed before the contactor, and only closes when the BAT switch is ON, this also is linked to that switch. The result is also, that loading a flat battery using the external power unit is also only done when the BAT switch is ON. It's not enough to just connect the GPU. So for the C182s I would really see our toughts as "confirmed by evidence" wouldn't you say?

For the C172 the schematics is not as clear. It looks like the GPU is powering directly bypassing the switch, but the POH also has the same wording as the C182S POH regarding "controlls all power to the plane". It does not have the "external power relay" but a "reverse polarity contactor" (assumingly doing the same, but the schematics do not show wiring to the master switch). Like with the 182, the POH says "The primary bus is on anytime the master switch is turned on, and is not affected by starter or external power usage". To me, that tells me its working like with the C182, namely, the BAT switch needs to be in the ON position to allow power from the GPU to reach the primary bus.

Thanks again for your help :)

See also https://github.com/c172p-team/c172p/pull/1496 Affected commit: 9f31da87c241091c3f6243802852576f1a5b8e25