Possible engine restart issue

[Maverick Su-35S]

Hi,

 

I've been trying to fly the BF-109 lately and as I've selected one that starts at the rampstart with the engine running (so the engine wasn't too hot and stood at idle for more than 2 minutes minimum, as the manual requests) I started "playing with the engine" a bit there by shutting it down then restarting it up then shutting it down again from the magnetos or from the fuel pumps by putting them to off or normally from the shuttoff yellow lever, and then at one time I suddenly found myself unable to restart it anymore!O.o

 

The behavior is that after asking the crew to run the inertial starter and they manage to spin the flywheel to the highest RPM, I press the starter switch which normally acts as a clutch actuator which engages the engine to the high RPM spinning flywheel, the engine is barely moving just like if it would be seized or it would have a very high friction in it, or else to say, the flywheel can't seem to have enough angular momentum to start spinning the engine anymore. So this would happen if you'd stop then restart the engine a couple of times and eventually you'll find yourself unable to spin it up anymore because it acts like it has no more lubricant or something like that...!

 

If this is a realistic feature and not a bug, I'd like someone to explain me why would this happen!

 

Many thanks!:thumbup:

Edited August 15, 2015 by Maverick Su-35S

[Flying-Kane]

Hi Maverick Su-35S,

 

I assume, the fuel pressure isn't enough to start the engine again.

Could you please check the fuel pressure gauge (the half yellow/brown gauge) over the rpm indicator? If that's the case, please use the fuel prime handle, by pressing it ca. 12 times.

 

For further investigation, provide us a video.

[Maverick Su-35S]

Hi Maverick Su-35S,

 

I assume, the fuel pressure isn't enough to start the engine again.

Could you please check the fuel pressure gauge (the half yellow/brown gauge) over the rpm indicator? If that's the case, please use the fuel prime handle, by pressing it ca. 12 times.

 

For further investigation, provide us a video.

 

Hi Kane,

 

Thanks for the reply! As I mentioned, the engine/propeller spins very slowly after pressing and holding the starter although the flywheel is spinning at it's peak RPM just before pressing the starter and this should have nothing common with having fuel or not, because with or without fuel the prop should be spinning at the same rate every time I restart the engine, but for some reason the prop starts to spin very slow after a given number of restarts.

 

Otherwise, in some occasions it doesn't even spin at all when pressing the starter button while you can still hear the flywheel spinning, just as if something mechanical would be broken and the flywheel no longer connects to the engine and although this happens much rarely, it does happen.

 

Here's the track with the slow spinning prop/engine:

 

BF-109 engine restart.trk

[Flying-Kane]

Hi Maverick,

 

I watched your video, now i understand what you mean.

 

I could start the K-4 twice, but afterwards, i had the same effect. I don't know, if this is a bug or works as intended...

 

Maybe Yo-Yo can answer your question.

Edited August 18, 2015 by Flying-Kane

[Maverick Su-35S]

Hi Maverick,

 

I watched your video, now i understand what do you mean.

 

I could start the K-4 twice, but afterwards, i had the same effect. I don't know, if this is a bug or works as intended...

 

Maybe Yo-Yo can answer your question.

 

Thanks Kane,

 

 

Let's see what Yo-Yo has to say!

Also, don't forget that sometimes the flywheel is spinning at highest rpm after the crew cranked it up and when you press the starter nothing happens but you can still hear the flywheel spinning..., so this also happens from time to time!

 

Let's hope for the best!

Edited August 17, 2015 by Maverick Su-35S

[Kelevra9987]

Have had the same Problem today. I was flying from Gaudata to Batumi, landed without a single scratch, taxied to parking, let the engine cool it self with radiators full open and 1000 RPM and after around 2 Minutes "idleing" I raised the Engine Stop Lever on the Throttle. After Refueling I was unable to start it again with the same symptomes as Maverick Su-35S has discribed them.

[Maverick Su-35S]

It's weird how nobody talked about this before, cause it's well into one year since it came in and it's obvious this is abnormal...!

 

 

Let's hope for the best!

[bart]

Ive had this issue with the K4 too but thought it was down to my miss management of the engine. I no longer go for long flights with a land away as there is no guarantee it will start for the return trip!

 

Looks like this may be a bug? surely the engine can not be this unreliable!? or wear out after 1 flight.....

Edited August 20, 2015 by bart

[NineLine]

Does a repair do anything for it? I'll try and have a look myself sometime. As for it being odd that it wasnt reported sooner, I dont think so.. I mean most people are dog fighting, not taking joy rides, stopping and starting at different airfields ;)

[Roadrunner]

Does a repair do anything for it? I'll try and have a look myself sometime. As for it being odd that it wasnt reported sooner, I dont think so.. I mean most people are dog fighting, not taking joy rides, stopping and starting at different airfields ;)

 

repair doesnt work there as the aircraft is not damaged, however, as workaround i jettison my canopy on the ground if i get into this situation. after that repair works normaly.

[NineLine]

Does the aircraft then start normally as well?

[Flying-Kane]

Hi guys,

 

i did further testing...

 

What i did:

 

Take off as normal. Landing after 5 minutes of flight and low engine stress. Engine out. Engine on. Engine out.

 

Now it's over, I can't start the engine anymore.

 

Repair isn't possible either, because no damage, so I jettisoned my canopy.

 

The repair is done after 180 seconds.

 

The start of the engine is possbile again. But i recognized 2 "bugs".

 

First one: After the repair, the canopy is there again, but only in the third person view! In cockpit view, there's no canopy!

 

Second one: I pressed the fuel handle as usual, but nothing happened to the fuel pressure, it was below the normal pressure value. So i expected the engine not to start, but surprise, it startet. The fuel pressure stood at the low value, but after i increased the power, the fuel pressure rised.

 

 

Can someone confirm this behavior?

Edited August 24, 2015 by Flying-Kane

[Roadrunner]

after you close the canopy with strg+C it is visual from inside the cockpit again ;)

[Flying-Kane]

after you close the canopy with strg+C it is visual from inside the cockpit again ;)

 

But isn't it a bug then? I mean, the canopy should be visible after the repair.:huh:

[Roadrunner]

yes, but at least its working for now that way, aye?

[Flying-Kane]

Yes that's correct. :)

[Art-J]

Just out of curiosity, I tried to replicate the starter glitch on my PC. Didn't even fly the plane, just started the engine, revved up for a minute or two to heat it up, cut it off - voila - the second engine start is not possible anymore, as the inertia starter clutch seems to be made of biscuit and doesn't catch anymore :D.

[Roadrunner]

actualy it seems to be a battery problem after all, dont ask me the "how exactly", but it is possible to start her up without my repair workaround.

 

to do so, you have to work with some of the circuit breakers, essentialy the idea behind this is to save as many energy as possible before actualy pulling the starter.

 

but as said, dont ask me which ones, every time i need it i have already forgotten how i did it and have to try 3-5 times, lol.

 

regards,

RR

[Flying-Kane]

but as said, dont ask me which ones, every time i need it i have already forgotten how i did it and have to try 3-5 times, lol.

 

regards,

RR

 

:megalol:

 

Maybe external power helps?

[Art-J]

The battery theory doesn't make much sense though, in this particular case :) . The hand-cranked inertia starter is strictly mechanical device, while any magneto-based ignition system doesn't require any battery as long as the crankshaft is rotating.

[Roadrunner]

i agree with you art-j, at least for real life logic. the problem is, that at least i dont know, how this stuff is programmed.

 

for example, we know of weapons still hanging under a wing on some aircraft after the wing was shot off.

 

RL logic says: wing off, weapons gone.

ingame the weapon locations are connected to the aircraft center by a relative position as it seems.

 

thats just an example to make my thoughts a bit better understandable :)

 

regards,

RR

[Laro]

This problem is still there.

Makes the K4 a disposable aircraft.

[DarkRaiderss]

I believe it's a battery issue as I was able to get the plane to start using ground power. Of course you could just get in another plane to avoid the issue. As a side note I've noticed after flying a long time (multiple landings and refuels) and using the mw50 a lot it seems that the tank isn't getting refilled. I eventually have to get a new plane when it runs out.

[Andy1966]

Hi All,

 

I fly the 109 quite a bit a and have experienced this quite a bit and did a lot of experimenting to find out why.

 

The manual says that the bf- 109 will not run without electrical power and they don't lie. I've had battle damage once (so the score window said) and lost the generator and the engine ran till the battery went dead and the engine lost fuel pressure and died after 10 or 15 mins. After sitting on the ramp without the generator charging the battery (i.e. sitting on the ramp idling or all the switches on and engine off) the battery becomes discharged Quickly and the fuel pump wont run fast enough to provide sufficient fuel pressure or supply the booster coils for the mags.( needed for starting) the generator doesn't cut in until 1200 rpms so don't idle below 1200rpms much.

 

I experimented on the ramp, and found that with all the switches on, and the engine off, you can hear the pumps slowing down,and the engine wont start after only a few mins (say 3-5mins depending on battery state of charge) so be very sparing with your battery power. the only thing that needs to be on to start is the ignition and I don't turn it on till Chief is turning the starter.

 

Also the engine seems to flood very easy when cold and even more so when its hot.

 

The remedy I've found for this is to turn all switches off, put the shut off on #1 only so only one fuel pump runs, too get fuel pressure initially and prime a cold engine, then turn it off. ( I use the selector lever).On a warm or hot engine, DONT PRIME IT. try a warm engine with no prime and ive found about 80% of the time it will start, and the rest a very small 1/4-1/2 stroke should do it.

Most of my difficulty starting and restarting after I figured out the battery goes dead very fast seemed to be related to flooding as I turned all fuel and magnetos off and opened the throttle fully and cleared the cyls 3 times then did a normal start up with 1 full stroke of prime and it coughed and sputterd and then caught. ((one time I even got a backfire, I Swear! WAs in a shelter and it scared the hell out of me... lol)) (set throttle about 1/3 to1/2, a little more open then usual).so if it just don't want to start, clear it out and hook up ground power AND DONT OVER PRIME EVEN A COLD ENGINE and it will start every time, but it may take a few tries.

 

After I figured all this out I can get 95+% success starting even down to -30 degrees c.

 

 

I usually try any start attempt with no prime first (or 1/4 stroke, below +10 c., just double click on the primer). always suspect its over primed and not under primed. you almost cant over prime a p-51, but the Benz is fuel injected and is very sensitive to flooding, but it needs a small amount of initial prime. and don't forget to turn on the fuel pump and generator right after the engine starts.

 

I have also had happen a few times where the engine would kind of half start and then kind of halfway run, and it took me a while to figure out that when it does that to just flick the mags off then back on, and it will clear out(guess the plugs were fouled?)

I found out the hard way to make sure your holding the brakes when you do that.......

 

When restarting a warm/hot engine, first turn off any unnecessary electrical equipment (Pitot and windshield heat, and radios come to mind) open the coolers and run at 12-1500 rpms to cool engine off before shutting it down(remember the battery is not charging below 1200 rpms)then use the shut off lever to kill the engine. turn battery and fuel shut off and don't forget to reset the engine shutoff lever to run and all battery switches off. then you will notice the fuel pressure gage still reads full fuel pressure, so no need to run pumps....

 

When restarting: when starter starts to spin, turn on battery, mags, ignition and then crack the throttle slightly and try first with no prime if it doesn't catch, a small 1/4 shot of prime should do it. then turn on fuel Pump/ shut off valve and generator

 

I really Like the 109 and from what I have researched and seen and read online, this is all normal and correctly modeled. almost all accounts of RL pilots describe difficulties starting (or not starting) especially on the eastern fro, weak batteries, lack of parts, fuel, etc. there is an interview with Gunther Rall on you tube that is a really good and informative interviews

 

Hope this helps, Andy

[LeCuvier]

Thanks Andy!

 

Grateful for the in-depth analysis Andy did. I also think the Bf-109 is very realistically modelled sim. The little complications around engine start give just a bit of an insight into the challenges of the ground crews at the time; especially at the Ostfront with arctic temperatures and then having to abandon airfields in emergency mode with mechanics stowed in the back of the fuselage as the Red Army bulldozed the Wehrmacht back West.