Warbird emergency power cooldown?

[Jafferson]

There are time limits for operation with war emergency power mentioned in the manuals for warbirds, but i cant find any info about cooldown times. I reduce Power and open the radiators to cool down, but i blow up my engines way to often. I got questions, how is the heat modeld in DCS? Its like a invisible value, but what kind of value? Is it a timer, heat, or helth? How can I cool down the engines back to a condition in which the emergency power time is fully available again?
If someone can explain, please.

[PL_Harpoon]

Two things.

 

1. It depends on a specific airplane.

 

2. There are no hard limits and it's all very dynamic. There's also no such thing like a cooldown timer or anything of that sort. Generally you have to watch all your temp gauges but this does not guarantee you're 100% safe from engine damage. The safest practice would be to not use WEP at all after exceeding max WEP time, don't exceed max temp on any of the gauges and keep the engine within the limits specified in the manuals.

[Jafferson]

There is something causing the engines to blow up, and i want to know what it is. I did a lot of test with different planes, even if i stay in the temp parameters and and cool down freqently, during flight and landings. At some point, the engine blows up. It feels like the engines taking damage during the use of WEP. I want to understand how it works, if someone got info, explain please.

[PL_Harpoon]

Like I said, it all depends on the aircraft.

Radial engines work slightly different than water-cooled ones. Also each specific engine has different limitations.

The best way is to look up the specific aircraft manual and check its operating limits.

 

For example in P-47 you can kill the engine by overboosting it, even if all temps are ok.

 

You can give us an example (a track file would be best but even a video or just a description could work) and we may be able to help you.

[grafspee]

1 hour ago, Jafferson said:

There is something causing the engines to blow up, and i want to know what it is. I did a lot of test with different planes, even if i stay in the temp parameters and and cool down freqently, during flight and landings. At some point, the engine blows up. It feels like the engines taking damage during the use of WEP. I want to understand how it works, if someone got info, explain please.

It is called detonation, this is the biggest threat for engine. Air Fuel mixture has limit pressure and temp, when one of this limits are exceeded mixture will self detonate. This is main power limit for petrol engines. Detonations are induced by combination of MP and rpm, Higher MP increasing chance of detonation, Higher RPM is decreasing chance of detonation (example 60"/3000rpm you are good, 60"2400rpm engine will be dead soon.)

Running WEP is bringing you closer to that point, continuously WEP run will rise temperature of the engine, you may not notice change in coolant temp it is only coolant temp not engine temp.

But in my opinion engine should not fail after 5min of WEP this is over done and it need to be fixed.

In P-51 manual it is said that after 5 hours accumulated WEP uses, engine goes for tear down for inspection. 5hours of WEP ride. DCS P-51 engine is dying after single use. 5 hours this is just crazy.

If it comes to WEP cooldown, you should at least give engine a break at continuous power for at least same time as on WEP.

Edited January 16, 2021 by grafspee

[Jafferson]

23 hours ago, grafspee said:

It is called detonation, this is the biggest threat for engine. Air Fuel mixture has limit pressure and temp, when one of this limits are exceeded mixture will self detonate. This is main power limit for petrol engines. Detonations are induced by combination of MP and rpm, Higher MP increasing chance of detonation, Higher RPM is decreasing chance of detonation (example 60"/3000rpm you are good, 60"2400rpm engine will be dead soon.)

Running WEP is bringing you closer to that point, continuously WEP run will rise temperature of the engine, you may not notice change in coolant temp it is only coolant temp not engine temp.

But in my opinion engine should not fail after 5min of WEP this is over done and it need to be fixed.

In P-51 manual it is said that after 5 hours accumulated WEP uses, engine goes for tear down for inspection. 5hours of WEP ride. DCS P-51 engine is dying after single use. 5 hours this is just crazy.

If it comes to WEP cooldown, you should at least give engine a break at continuous power for at least same time as on WEP.

 

I think the same, damage of the engines using WEP is overdone. I found a interesting video about the P51 supercharger, he mentioned its the after-cooler heating up during the use of WEP. He told 1 minute with stabalized temperatures shold be enough to re-use WEP. At 16.25 min..

 

He also mentioned in the video, 67 manifold pressure was a factory setting for 130 octane fuel. But in battle over britain they used 150 octane fuel, abel to use a manifold pressure up to 75. At 12.32 min..

 

 

[grafspee]

Iirc in Battle of the Britain time period P-51 didn't exist. And high grade fuel appeared in late 44 or mid 44, and after 150grade fuel was tested in P-51 75" was stated as safe MP. But actually Air command decided to use 72" probably concerned about reduced engine life time.

In case of P-47 where we have 52" take off limit, i totally agree that pushing more  will for certain damage the engine, if you push more a little engine may fail at next flight, if you push a lot more engine may fail right there at take off.

But if you are using engine with in limits of the engine chart and we experience fatal damage to the engine. This is just wrong. 

BTW 100/130 fuel which was common used in allied air forces was really top notch fuel. As far as i know US air force didn't get any significant boost or wide use of this high octane fuel. But Royal air force got some significant boost for their planes. I thin spitfire MK IX used 25lbs boost which translate to 80" which is a lot.

Take notice that both DCS spitfire has same max boost, 18lbs of boost = 67" difference is that P-51 has stop wire for this boost and pilot had to report every use of WEP on the British side in Spitfire it is just normal operation range not stop wires no reporting of 18lbs is required. Even more in late Pilot's notes Flight instructions it is stated that spitfire can take off at 18lbs.

Edited January 17, 2021 by grafspee

[Jafferson]

Ok thanks for the info, but lets come back to the engine damage.

I did some testings, surprisingly the P51 had the best duribilty with 30 min continuesly 69 MP. So you can use WEP 6x5min.

BF109 was able to run 20 min. The poorest was the FW190D with 10 min.

Spitfire and A8 was not tested.

 

I bought the P-47 some days ago with the hope he can do better, i did a test with max power all radiators open. After 15 min the water was burned, reduced power to normal conditions, short after landing the engine died.
In the second P-47 test i tryed 3x5min with 5 min cooldown time in betwene, the engine died short after the water was burned. So cooling down have no effect at all.

The Engine got a lifetime of 40 min with 3000RPM Max Throttle + Max Supercharger without Water. 

Looks like the engine can run forever with Max RPM and full throttel without supercharger. I think the deterioration starts as soon you use the Supercharger.

What i found was, when the water is burned, its not posible to refuel it.

The damage on the engine during the use of WEP can not be repaired, repair can not be done until the engine is complet dead. And its the same for all Warbirds. Its really anoying that the only way to fix the engine damage is to respawn the Plane after landing.

Edited January 29, 2021 by Jafferson

[razo+r]

A8 can currently run max power for at least 45min continuous.

[grafspee]

P-51 can do 67" not 69"

In p-47 you need to watch your carb temp it will rise up a lot. So at high altitude you probably will be limited by this at what MP you can run engine same as in warm weather.

In p-47 you don't need to open all radiators, cowl flaps should be close in all level flight situation you may have to open them in high power climb depends on outside temp.

Same with oil leave it on Normal position, only intercooler you would need to adjust if carb temp going too high.

In that type of engine damage it is matter of time, only depends how large damage was done.

 

8 hours ago, razo+r said:

A8 can currently run max power for at least 45min continuous.

A8 engine power settings are not high, 40" at 2700rpm not sure about rpm. High octane fuel, very efficient cooling. I don't see any reason why this engine could not run full power for that long, by doing that you would definitely cut engines life to half or even more, but catastrophic engine fail due to detonations very unlikely.

5min limit was probably to achieve as much hours of the engine as possible. Difference in speed 1.4ATA vs 1.3 ATA is very small

Edited January 19, 2021 by grafspee

[PL_Harpoon]

Keep in mind that engine damage in DCS is randomized to a degree (probably to simulate flying aircraft with different mileage).

[Ala13_ManOWar]

Haven't tried recently but for instance P-51 can run a whole hour in WEP as long as you keep the speed high and there's fuel in the tanks. It's not random at all, it's no bug, it's not overdone, it's just temps are modelled as well as all the factors influencing them, as long as you keep speed high (say 300mph in P-51, or more), so airflow reaches the radiators (which is calculated), engine is good to go all the time you want. Just drop the speed too much without caring engine settings and it'll blow instantly. Of course IRL using the engine so harshly would mean a new engine the next time which is the reason behind the 5 and 10 minutes recommendation in the manual, but here you have a brand new engine every time you hit Fly button. My point being, engines doesn't blow up, careless pilots blow them up.

 

BTW, you didn't even mention which aircraft you're blowing up, not every one of them behaves the same, non of them does indeed. What aircraft are you having troubles with?

 

S!

[grafspee]

On 1/21/2021 at 7:20 PM, Ala13_ManOWar said:

Haven't tried recently but for instance P-51 can run a whole hour in WEP as long as you keep the speed high and there's fuel in the tanks. It's not random at all, it's no bug, it's not overdone, it's just temps are modelled as well as all the factors influencing them, as long as you keep speed high (say 300mph in P-51, or more), so airflow reaches the radiators (which is calculated), engine is good to go all the time you want. Just drop the speed too much without caring engine settings and it'll blow instantly. Of course IRL using the engine so harshly would mean a new engine the next time which is the reason behind the 5 and 10 minutes recommendation in the manual, but here you have a brand new engine every time you hit Fly button. My point being, engines doesn't blow up, careless pilots blow them up.

 

BTW, you didn't even mention which aircraft you're blowing up, not every one of them behaves the same, non of them does indeed. What aircraft are you having troubles with?

 

S!

Not true, i can slow down below 200mhp in p-51 w/o engine blowing instantly. I had engine fail after long flight, some times engine banged on airfield. I don't know is it fixed or not.

And you can blow engine w/o exceeding temps. Oil temp and coolant temp is not only thing you need to check.

[Ala13_ManOWar]

Yep Grafspee, it'll blow instantly depending on how much you lower your airspeed, which is obvious and that's why I didn't even think on mentioning it. Also remember there are "birds" and random failures in DCS, depending on everyone's settings, of course, which is obvious and that's why I didn't even think on mentioning it. But thanks for mentioning the obvious, you're so smart and know so much, thanks, thanks .

 

S!

[grafspee]

6 minutes ago, Ala13_ManOWar said:

Yep Grafspee, it'll blow instantly depending on how much you lower your airspeed, which is obvious and that's why I didn't even think on mentioning it. Also remember there are "birds" and random failures in DCS, depending on everyone's settings, of course, which is obvious and that's why I didn't even think on mentioning it. But thanks for mentioning the obvious, you're so smart and know so much, thanks, thanks .

 

S!

It will not i many times over shoot coolant temp while flying. Cooling system will vent excessive pressure to protect cooling system from rupture, engine will continue to work until most of coolant is gone, only when temp will increase by a lot engine will die. Same with oil. For WEP engine all is allowed to go higher then normal max oil temp. 

We must have flown different P-51, keeping temps below max don't protect me from engine blowing up, and exceeding max temps for short period don't instantly blowing my engine up.

Edited January 26, 2021 by grafspee

[Ala13_ManOWar]

Problem isn't that, and you know it. As long as you get to a situation in which high temps can't be handled by the system you'll blow the engine, blow, seize, whatever maybe of course but still the kind of damage is irrelevant to the point. You can either not blow the engine with good management no matter what the manual says, or blow it with bad management, and either way it's true to real life, period .

 

S!

[grafspee]

6 hours ago, Ala13_ManOWar said:

Problem isn't that, and you know it. As long as you get to a situation in which high temps can't be handled by the system you'll blow the engine, blow, seize, whatever maybe of course but still the kind of damage is irrelevant to the point. You can either not blow the engine with good management no matter what the manual says, or blow it with bad management, and either way it's true to real life, period .

 

S!

This is issue here, engine blowing up even when you stick to engine chart.

[Ala13_ManOWar]

5 hours ago, grafspee said:

This is issue here, engine blowing up even when you stick to engine chart.

Since that never happens to me without my intervention in some way or another I can't say it's not due to ill management, no matter if people notice it or not.

 

S!

[Jafferson]

I found a post about the Engine model. Its impressive to see they trying to simulate cylinders, magnetos and so on

 

https://forums.eagle.ru/topic/254149-engine-damage-after-only-flying-around/?do=findComment&comment=4526705

[Snapage]

Regarding the P51D, as far as I know engine failure after using WEP is random. This includes temps being in the green and running it for less then 5 minutes. After breaking the wire and running 67" for any time period the engine has a random chance of failing.

 

I don't use WEP at all in the P51D because the resulting random engine failure takes me down more often then the threat I am trying to avoid.

 

Though lately I have been getting more and more engine failures from running just 61" with all temps in the green.

[grafspee]

22 minutes ago, Snapage said:

Regarding the P51D, as far as I know engine failure after using WEP is random. This includes temps being in the green and running it for less then 5 minutes. After breaking the wire and running 67" for any time period the engine has a random chance of failing.

 

I don't use WEP at all in the P51D because the resulting random engine failure takes me down more often then the threat I am trying to avoid.

 

Though lately I have been getting more and more engine failures from running just 61" with all temps in the green.

Some ppl can run WEP in P-51 for hours with no problem.

[Snapage]

9 minutes ago, grafspee said:

Some ppl can run WEP in P-51 for hours with no problem.

You can have the throttle fully forward with wire broken and not be running at 67". When ever I have used WEP my engine has failed 90% of the time even while keeping temps in the green. As far as I can tell I think its a timer that breaks the engine at a random point in time after using WEP.

[grafspee]

2 hours ago, Snapage said:

You can have the throttle fully forward with wire broken and not be running at 67". When ever I have used WEP my engine has failed 90% of the time even while keeping temps in the green. As far as I can tell I think its a timer that breaks the engine at a random point in time after using WEP.

Exactly same as me, sometime engine get seizure bang on airfield after engine was off.