I can't stay quiet here.
I learned to stop the engine of a c152 or pa28 or any other small plane with setting the mixture to lean!!!!
The reason is: no combustible mixture makes it very shure that there is no backfiring or ignition when the prop of a hot engine is accidentily moved, even with ignition set to on.
To stop a airplane engine by switching the ignition (magnetos) off is dangerous and just plain WRONG!!!!
And of course a airplane engine is constructed to run without external power, be it generator or battery.
Those are only needed for auxilary systems!
The "Kommandogerät" of the FW190 could be set to manual override if i.e. the electric was lost.

Actually, a lot of things are done differently depending on aircraft type. I don't know what happens in aero clubs, but in the army the preferred method to shut down pretty much anything seems to be cutting the mixture.

I saw this when serving my conscription tour as a flak gunner on Rheinmetal 20mm twins. These guns are operated with the aid of a 160cc wankel engine. During training they told us there's two ways to stop that engine, pressing the stop button or cutting the fuel supply. When we asked which is best, they told us "stop button for emergency only, fuel cutoff for everything else".

Months went by, i got posted to a unit, started doing the things a soldier does and at some point i got posted to the unit's AA company and came in contact again with the Rheinmetal guns. Each day we'd take a different gun out of the hangar, so that we checked all of them in rotation, set it up for firing, etc. Sometimes we took out the same gun after only 3 days or a week and that's when i understood their obsession with fuel cut-off. Depending on weather conditions, the exact same engine on the exact same gun driving the exact same hydraulic actuators would run smooth as butter one day and give us hell to start the next one. There's no sophisticated mixture control in that engine, just an ignition, a primer and a pull-cord starter. When people swtiched the engines off by pressing the stop button and not cutting the fuel, what happened was that unburnt fuel was left inside the engine. Depending on weather, the next time we wanted to start that engine the amount of fuel left in it could be wrong for the weather we had at that day.

If it's insufficient you can prime some extra fuel into it, but if there's excess fuel in the chamber all you can do is spend 5 minutes pumping out the excess fuel and clearing the engine by repeatedly pulling on the rip-cord starter with the ignition and fuel supply turned off,which is not very pleasant during peacetime and bad weather, or worse, during an actual air-raid. Hence the "always use the cut-off" emphasis.

It's a similar case for aircraft engines, even though they differ a lot with their huge displacement and compression ratios compared to a puny 160cc wankel, what mattered the most was making sure the engine will run when you need it the most and not that it will run for the longest amount of years. Better have a "dry" engine that needs to be primed before start, than have an overflooded engine that needs to be turned without ignition to be cleared before being primed before being started during a scramble call.
That's the reason most of the restored warbirds are ran at different power settings than the wartime values, in the war they wanted to ensure performance when they needed it the most, but in the airshows the main care is to ensure maximum component life so as to keep them flying for longer.

Also, you say this
but it makes it seem like it all goes dark in a split second. What you say next is a better description

"For long" being the operative phrase. If you switch off everything you don't need, there's an airfield within 20 miles of your position and you get priority/emergency clearance by ATC, i guess you could make a safe landing without a generator, running only a couple of instruments from the battery. Of course, it would be a different story at night where you need more radios, more light equipmeent and so on.

Actually that is exactly what azimech was hinting at. Dead generator--->need to conserve battery to RTB--->player will have to choose what to keep running and what to turn off=interesting gameplay.

S!

In modern jets if you lose the generator then batteries are designed to work for about 30min(back-up instruments and some other systems), to give you time to get to safe or even land if possible. The engines run and if they do then are the hydraulics working, but with batteries the FCS computers won't work as they require more voltage than a battery can provide, so you are on a backup system that gives limited aircraft control. This causes landing speed to be high thus in most cases it is safer to eject after flying out to a safe area. In a WW2 plane you could land easier and have less hassle if losing the generator and running on battery..depending on the plane of course.

I haven't made myself clear:

switch off procedure:

1) taxi to parking
2) ancillaries checklist (flaps, brakes etc..)
3) mixture to lean
3) throttle to idle/cutoff (if present)
4) engine stops detonating
5) magnetos off

now the engine is off

you can take the engine to idle and switch it off with the magnetos, which is not dangerous at all, it is actually considered safer because even if there is some mixture residue (you might have a faulty inlet valve for instance), there will be no spark from the plugs in case of accidental prop swinging.

I didn't know you could override the kommandgerat, where were the manual controls for the engine?

Guys, I have hundreds of hours on single engine propeller planes, and I don't mean to brag but I think I quite know what I'm doing when flying (and switching an engine off).

Blackdog, I know it sounds like that, but in some planes a dead generator really means the games are over in a split second.

Comparing the use of high compression engines with low ones (aeroclub boxer engines vs wartime radials or inline) is improper. We takeoff the Mustangs with never more than 75% throttle simply because there's plenty of power to do everything and above all you don't want to over stress cylinder banks that are 60+ years old, but in the warbirds circuit there are several pilots that firewall their engines, which often means catastrophic (and very costly to repair) damage. We had a case a couple of years ago of a mustang pilot who used to takeoff at full military power (or WEP) and who had a major failure fortunately once on the ground.
Cutting off engines by leaning the mixture is considered a bad habit by some, while others think it's perfectly fine. I think it's all down to the machine you're flying with and environmental factors.

and once again, an engine is not considered safely switched off until the magnetos are on, and that is the same for every plane.

Military procedure yes, and we're talking about a military flight sim.

Here's a nice read for you, dual ignition really is meant for a better burn in those big-bore engines. It even lessens the risk of engine knock!
http://www.avweb.com/news/pelican/182132-1.html

That's not what I read in electrical schematics of aircraft.

Batteries warm up while charging, and during flight, they are continuously charged unless charging is shut off manually.


That's why I started the topic in the first place! The battery won't keep it for long is something else than immediately dead systems.

Kommandogerät is one example, prop pitch governor on the P38 is another. The mags will work anyway and if the rest fails, you still have a chance to get home.

Alfa Romeo have often employed dual ignition since the 60s for a leaner burn and higher power. Igniting the mixture at two different points caused a quicker burn and allowed tighter timings.

Don't know anything about this regarding fighter a/c, though. Presumably if dual ignition was used to tighten timings, knock would become a serious issue if one circuit was knocked out. OTOH, a dual system would provide redundancy but only a tiny increase in power if the ignition timing was the same as a single-ignition setup.

dduff

Thanks for the clarifications sternjaeger. It makes more sense now and yes, i agree that for an engine to be considered safely off the pilot needs to also switch off the ignition and not just the fuel supply :grin:

The KG is not driven by the battery or the generator, It is mechanical in the BMW801 series and hydraulic in the Jumo 213 series. It uses the mags and is not affected by a loss of systems electrical power to advance the timing.

The VDM propeller only uses electrical power for emergency operation which the KG does not control. In normal operation it is a hydraulic governor and is a normal CSP.