TF-51 engine just goes boom after engine-start??

Please check track-file: https://ufile.io/lz4e3cfj

Was it a fresh plane ?

Wow your throttle movement are crazy :P Let the engine idle for a bit :P

yes. and yes, I didn't have much time, in BlueFlag, sometimes every minute counts xD

yes. and yes, I didn't have much time, in BlueFlag, sometimes every minute counts xD

I would say that

Your oil temp was around 30 C coolant around 50 C - 60 C i don't see any reason why engine would seizure like this.

My Vote = not realistic.

yep, same vote.

I would say that

Your oil temp was around 30 C coolant around 50 C - 60 C i don't see any reason why engine would seizure like this.

My Vote = not realistic.

Engine wasn't allowed idle/warm up before taking power = dry engine bearings = seized engine.

Couldn't reproduce OP's issue when doing 1000 rpm warm up, etc.

since which OpenBeta version is that "warm-up" mandatory? Wasn't mandatory like 6 months ago it seems... o_o

aaaah yes, oil pressure still was super low I think, that would indicate dry bearings?

cold oil is thicker. and it takes more pressure to force it through the system. so you actually need to wait for the oil pressure to drop.

it also will not lubricate piston rings and the big end bearings properly.

why you should not push an engine until it is at operating temp. and the oil is flowing freely.

high performance engines in fighters are being pushed near their mechanical maximums when at operating temps. to get the performance.

not waiting is the easiest way to kill them.

when a hot engine is stopped the warm oil freely flows into the sump, under gravity, and cools. it takes a while for that cold oil to recirculate around the engine when you first cold start it again. the top of the engine basically has no oil in it. and you have to get all the oil in the sump up to operating temp.

overcooling is an issue in flight. if you descend for long periods in a glide. instead of descending under power.

us periods of maximum engine RPM to warm the oil. even if you don't use throttle.

high oil pressure = cold oil

medium oil pressure = operating temp or not enough cold oil.

low oil pressure = not enough oil

why you have both oil pressure and oil temp gauges.

use periods of maximum engine RPM to warm the oil. even if you don't use throttle.

this method used in real prop aircraft? If so, source please?

it says it in the spitfire manual.

its the same engine.

from the manual under gliding descent.

2. Avoid overcooling the engine. On lengthy gliding descents, raise the engine RPM to 2400-2500 for 5-6 seconds every 3-4 minutes.

interesting!! thx

Or just switch heating on, I guess

Once again,

Oil temp + 30 C

Coolant close 60 C

minimum requirements for Take off fulfilled.

If you have oil pressure present this mean that all bearings(whole oil system is filled with oil.) are filled with oil.

High oil pressure is because oil pressure regulator is out of the range.

This is made for purpose because oil at low temp has big viscosity, and it require a lot more pressure to feed bearings in reasonable time with sufficient oil flow, but as soon oil reach all bearings the pressure needle will jump up. (Oil pressure is rising so fast in P-51, this mean that ground crew had to run this engine couple minutes before your start up. There is no way that oil pressure would jump so fast if oil system was dry after night in hangar.)

Ambient temp was s high that engine was almost pre-heated for take off.

You don't want to rev engine while oil is cold, excessive oil pressure may damage some parts. I usually try to not go above 150 on pressure gauge.

Btw if it come to over cooling P-51, oil will not be over cooled. Issue stays only with coolant, over cooling has adverse effect, engine can not respond to throttle properly, while coolant is below 60C, but not a engine seizure like this. Not a single engine would get to aviation if it was acting like this, because you advanced throttle a little too much LOL.

I will tell that K-4 has no problems with it, even when you take off with below min temps. You can start engine with throttle fully open and just take off, from where you spawned

since which OpenBeta version is that "warm-up" mandatory? Wasn't mandatory like 6 months ago it seems... o_o

Pretty sure I blown engines by not warming up a year ago at least.

IIRC the P-51's Merlin has had this modelled from the beginning.

Pretty sure I blown engines by not warming up a year ago at least.

But, he warmed up engine. Minimum temps for take off is 15C oil and 60C coolant.

He had that.

The DCS P-51D manual says 40'C oil (and 60'C minimum coolant). But forget the DCS manual and read the real manual (April1944).

It does say 15'C (see 2nd pic) but in warmup it emphasizes gauging oil pressure with throttle opening. Did an experiment. Watched oil pressure and temps. Found that:

1) To be able to apply full throttle without oil pressure redlining, you must wait until 70'C oil temp (start of green arc).

2) But with oil diluting (note, max 2 minutes) one can apply full throttle at lower temps (55-60'C, don't quote me). Note the Emergency Takeoff note.

Oil pressure is what really matters it seems. And you gauge that by applying throttle and watching the oil pressure.

A max throttle takeoff requires 70'C oil temp to avoid exceeding oil pressure. But, in a hurry, one can oil dilute to keep oil pressure down and still max out throttle at lower than 70'C. A third option is applying less than max MP (MP 30 is good enough for takeoff), this will keep oil pressure below redline at lower than 70'C.

To be real finicky about it ... the autostart script goes to 1300 rpm and exceeds oil pressure max, not good. Read elsewhere that 900 rpm is good for warmup (the guy who

900 rpm is good idle.

Warm up is done at higher rpm.

But this only while starting up in cold weather.

if you have +30 out side you are almost warmed up.

It can not end up with engine seizure like this.

Btw DCS P-51 can take throttle even at -10C :)

Manual states that engine may have problems to react properly on throttle movement.

900 rpm is good idle.

Warm up is done at higher rpm.

Good idle, fine!:).

But autoscript 1300 rpm does redline oil pressure which is not a good look. So 900 rpm warmup until 1300 rpm can be applied without redlining (a minute maybe).

Overall, the manual makes perfect sense to me. Cold thick oil = no lubrication (which can be mitigated with gasoline oil dilution). Nurse warmup with/without oil dilution (autoscript does oil dilute), the important thing is to never redline oil pressure.

Good idle, fine!:).

But autoscript 1300 rpm does redline oil pressure which is not a good look. So 900 rpm warmup until 1300 rpm can be applied without redlining (a minute maybe).

 

Overall, the manual makes perfect sense to me. Cold thick oil = no lubrication (which can be mitigated with gasoline oil dilution). Nurse warmup with/without oil dilution (autoscript does oil dilute), the important thing is to never redline oil pressure.

Red line is 150-200 i think.

But just main concern is to get minimum oil pressure level, if oil pressure is too low this indicate some damage in oil system.

Please check track-file: https://ufile.io/lz4e3cfj

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Doesn't matter anymore, we figured it was overheating of engine component. (file was available for 4 weeks...)