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Cannot start engines though having APU running


Kastendrachen
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Hello,

I just experienced a problem with my Catalina. Yesterday I landed somewhere in the Baltic Sea and switched the whole plane off to go to sleep. Now I reloaded the saved flight, switched APU and battery and some lights on and wanted to start the engines. But I saw that the cockpit light was off though the switch was in "on" position. So I switched all off and restarted APU and checked voltage. It was pretty much below 20 Volts, I thought it was just a little bug and tried to start the engines. I don't know if I did hear the fuel pump but when I engaged the starter, nothing happend. It didn't even crank.

So I now enabled "electric always available" to avoid this problem again because I don't want to reload the plane everytime I rely on the APU and see it does not work. Was this just a bug and because of reloading a saved flight? And yes I did engage the APU-Gen switch but not even the little green lamp wanted to shine.

If this is a problem which cannot be avoided I plan to take down the minimum voltage of the right engine so this engine would start always and so act like the APU or leave the "1" at the electric always available section.

I have never had this before so does the APU actually produce or permanently provide current or does it exhaust itself the same way the battery does?

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  • 3 weeks later...

Ok that makes it clear. And today I wanted to do a little flight, it was raining and the temperature was I believe somewhat above 20°C like it is always in FSX even if the real weather shows ten below zero. Nevermind. I followed the procedure and the engine fired and RPM went up. Then I pulled the throttle slightly back due to the problem that I else would have hit some structure in front of me because the plane moves even at zero power...things I hate FSX for. Well I pulled the throttle slightly back and RPM sank, Fuel Pump and Primer were still on, I pushed throttle forward but....RPM sank even faster till the spark plugs were fouled...and I started pushing throttle at approx. 1700 RPM so I've been well over the 1000 RPM limit. But I don't understand why, it fired correctly, I could control it for a few seconds and then out of nowhere it went off....I also pushed the prop pitch in Full RPM position before but the engine died. I thought at least the other one would do like it should but it was the same procedure. But the left one died even faster. I then wanted to taxi the plane to a waste zone :D

And...is it possible to write a gauge that simulates an APU? I saw that there is almost everything possible with XML gauges, I could even integrate a coffee machine (and if I wouldn't be so lazy, I'd already have it done :D ) so there should be a possibility to add a virtual device that always provides power. Or could one define the APU as a number 3 Generator? So that the APU starting is treated by the game like starting a third engine (with a minimum starter voltage of 0 or something) and switching the generator switch does engage a "Generator 3" and thus would provide power.

Would this be possible or are there further restrictions of the game itself?

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Ok that makes it clear. And today I wanted to do a little flight, it was raining and the temperature was I believe somewhat above 20°C like it is always in FSX even if the real weather shows ten below zero. Nevermind. I followed the procedure and the engine fired and RPM went up. Then I pulled the throttle slightly back due to the problem that I else would have hit some structure in front of me because the plane moves even at zero power...things I hate FSX for. Well I pulled the throttle slightly back and RPM sank, Fuel Pump and Primer were still on, I pushed throttle forward but....RPM sank even faster till the spark plugs were fouled...and I started pushing throttle at approx. 1700 RPM so I've been well over the 1000 RPM limit. But I don't understand why, it fired correctly, I could control it for a few seconds and then out of nowhere it went off....I also pushed the prop pitch in Full RPM position before but the engine died. I thought at least the other one would do like it should but it was the same procedure. But the left one died even faster. I then wanted to taxi the plane to a waste zone :D

And...is it possible to write a gauge that simulates an APU? I saw that there is almost everything possible with XML gauges, I could even integrate a coffee machine (and if I wouldn't be so lazy, I'd already have it done :D ) so there should be a possibility to add a virtual device that always provides power. Or could one define the APU as a number 3 Generator? So that the APU starting is treated by the game like starting a third engine (with a minimum starter voltage of 0 or something) and switching the generator switch does engage a "Generator 3" and thus would provide power.

Would this be possible or are there further restrictions of the game itself?

Please check Your weather.

With rain and low temperatures You must expect Carburator icing.

Switch on the carburator heat switches just until the carburator temp gauge shows 35°C then switch them off again.

When throttling up check that the carburator air temp doesn´t get below 32° and not above 50°C either.

Finn

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Thanks for your answers. :)

The first thing....my engines didn't even live as long as necessary to build up heat. They died after a few seconds. Does the carb heat work even if engines aren't running? That would be....strange cause there would be no hot exhaust gasses^^

And....somebody on the fsdeveloper forum told me that there are key events for switching the APU and he said that the APU is not restricted to aircraft type...I don't know how FSX manages the availability for APU maybe he was wrong. It would be nice if I could get some information about how it works internally to find a solution. As for now, I have to enable "electric always available" to prevent battery exhaust. Does the battery exhaust even when it (battery master switch) is shut off? Because then I would just connect all devices to the battery bus so that there is no consumer if the master battery switch is off. Only if that has an effect. By now some lights even glow when all power switches are off. That is another problem...I conencted the strobe light to either Generator or battery bus but it flashes even if engines are off and battery is off. I think that's just a bug? So does the strobe consume power even if every power supply is off or is it just a "cosmetic bug" that doesn't waste battery? This question stands for all electric devices that may work even though they should not.

The reason for me to ask this is that I am not just a "get in, warm up, fly away, land, shut off, go to bed" pilot but I sometimes have the plane stand on the ground for a while and it sucks when you come back to do a new flight and you find that something wasted your battery. So a WORKING APU is essential for me ;)

I know that FPS saving is essential and I don't want a new visible gauge for APU but gauges are in fact "devices" so a gauge with a few lines of code that works in the background would do the job quite well because there is nothing left in the cockpit in regarding visual presence ;)

And please don't take my interest and questions as criticism, I just love this plane so much that I want to do a little tiny work to add another bit of functionality and to go around the existing restrictions.

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Critisism is always welcomed...

APU in FSX only works for Jetpowered aircraft - sorry.

Instead of the "Electrical allways available" try to set each consumer listed in the [Electrical] section to 0, 0, 0

Carb heat only works with running engine(s). But right after startup switch the carb heaters on until carb air temp is more than 35°C, but less than 47°C.

Note that the Carb heaters on the Catalina aren´t simple On/Off switches.

You should see it as Increase/Off/Decrease switches instead.

A small damper in conjunction with the exhaust pipers will divert more or less intake air through aheatexchanger on the exhaustpipes.

This means that carb air temp with carb heat dampers more or less open will also depend on the exhaustpipe temp i.e engine power output.

Also keep engine RPM above 1000 RPM to prevent sparkplug fouling.

When starting the engines You need to keep priming the engine with the priming switches until oil temp reaches 40°C.

When oil temp is higher than 40° priming is no longer needed.

During start mixture should be set to either Auto rich or Full rich.

Finn

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  • 2 weeks later...

Given what you say about the availability of APU according to aircraft type, I wonder how A2A managed to get the APU in the B17 to deliver power...

The Accusim B17 certainly manages to utilize the APU...

Then again, that is possibly an "outside the box" solution...

Andrew

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Given what you say about the availability of APU according to aircraft type, I wonder how A2A managed to get the APU in the B17 to deliver power...

The Accusim B17 certainly manages to utilize the APU...

Then again, that is possibly an "outside the box" solution...

Andrew

Not only an `outside the box` solution but actually a faux one, although very very cleverly done. The B17 is not using the APU to start the engines. It is a sleight of hand... there's some clever gauge trickiness going on to make you think that it is. It's more a `battery extender` a la FSUIPC...

As stated NO piston-powered aircraft in FSX can use an APU to start the engines. In fact, I'm not aware of any piston powered aircraft that does so in real life. APU's are generally small engines mounted a distance away from the main units, so not sure HOW they would even start an engine?

Got any examples?

APU's are generally used to provide Ground Power in the absence of a GPU and not to directly start an engine. In fact it's difficult to see HOW this could be done with a spark-ignition engine unless the APU was capable of delivering not only the momentum to spin the inertia starter or the prop, but also supply the high voltage to perform ignition.

Things are different with turbines...

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Snave is correct...

We could have faked the Catalina APU, but that would have required a custom programmed electrical system and still be fake.

We found that most users rarely would use the APU, so we didn´t spend alot of time and resources to make it realistic, but liked to add the sounds and controls for it, cause it is rather special.

Finn

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