Hobbs meter

jmarkows

I am apparently differing from everyone else who is having issues with the Hobbs meter not saving between sessions, my Hobbs meter is not incrementing at all...

jmarkows

@Black-Square any thoughts on why the Hobbs isn't increasing at all for me? It's only at 0.1 hours when I've had the master battery on for far longer; at least the hour I've put on the engine.

Edit: seems like it's only counting time I'm in the air?

fizzboy

The Hobbs meter in MSFS only increments when a certain threshold such as airspeed or RPM is met.

jmarkows

There's no way they did that... did they? That doesn't sound like that's how it's supposed to work.

fizzboy

https://docs.flightsimulator.com/msfs2024/retail/programming-apis/simvars/aircraft-simvars/aircraft-engine-variables/#GENERAL-ENG-HOBBS-ELAPSED-TIME

This records the time the engine has been running, but instead of taking a % of the time based on the Pct/RPM this takes the full time, but only if a threshold RPM/speed is reached.

fizzboy

The way MTBF works is there isn't an "accumulated time" for any given component. It's more like on some particular interval the universe rolls dice and if it rolls all ones then the component fails. Also, there are a lot of dice and they have a lot of faces and the size of the dice depend on that MTBF number. Each roll is independent of all of the previous rolls (there is no memory).

So the Hobbs meter in MSFS is just a fun role-play thing you can look at while you imagine you're taking your fake plane to the fake mechanic to have your fake inspection. It's not implemented correctly but it also really doesn't matter at all.

jmarkows

That's the engine meter, I'm talking about the general one on the center pedestal that's supposed to tick onwards as long as the battery master switch is on.

fizzboy

Well... you're right in that the manual on page 48 states:

The included Hobbs timer in the aircraft runs from when the master switch is activated, to when it is shut off.

The XML code for the subpanel gauges on the Commander 114 all use the GENERAL ENG HOBBS ELAPSED TIME simvar (the same one as the documentation I linked to above) to determine what numbers to display on the Hobbs meter (the 6 digit gauge with a maximum of 99999.9 hours). Flipping the battery master on, I can observe that the value for that variable does not change at all (the floating point value will be accurate down to like the 10,000th of a second or so). Some time later if I'm especially curious I'll figure out what the rough RPM/speed threshold is to get it to start incrementing.

So either the manual gets updated to reflect how Asobo accumulates time to that variable or something. I doubt Asobo will ever change how that simvar records time.

The XML also refers to a gauge with 5 digits (TachometerDigit1 through 5 so a maximum of 9999.9 hours) and that uses GENERAL ENG ELAPSED TIME which is "Total elapsed time since the indexed engine was started." according to the simvar docs. I don't think it's actually on any of the panels or gauges, however. I could have missed it, though.

fizzboy

pfft... the tach hours are on... the tach. obviously.

jmarkows

I did some crude digging myself through the SDK and didn't see any of the entries the SDK suggested for minimums before Hobbs time starts ticking upwards.

If this is user error on my part, someone feel free to tell me, but based on the manual I would expect to have far greater time on my pedestal Hobbs meter than on the tach meter because my Master Battery switch has been on for far longer, but in practice I have about 1.8 on the engine and 1.1 on the pedestal.

fizzboy

In the engines.cfg documentation for the SDK, it says that the default airspeed minimum for the Hobbes elapsed time is 25 knots. So given that, you should have less time on the Hobbs meter than the tach time.