Destroying my R2800

[Bozon]

I can manage the engine heat just fine. The problem is with hidden limitations that involve “X time above RPM 2550” / “Y time man. Press. over 52”” etc. - I can’t seem to manage those. End up ditching almost every sortie that lasts over 20 minutes.

 

I keep my engine at 2500 rpm at all times. Boost lever is coupled to the throttle. Temperatures are in the blue ALL the time. I hardly ever go over the 52” line, but I do spend quite a bit between 52” and the green area of manifold pressure. Is this my problem?

 

If I push the RPM to full the engine gets destroyed in 60 seconds. If I do occasional bursts of full throttle + water the engine survives quite a bit, but still ends up  coughing and dying (maybe because I also touched the rpm) - the engine starts to cough when temperatures are still in the blue, and then start to shoot up.

 

I thought the limits were about 15 minutes at 2650 rpm and 5 minutes above 52” man. Are these summed total for the entire sortie, or is there a cooldown? 
 

Is there some indication as to how long I can still keep my rpm at 2650? Or man press above 52”?

 

[razo+r]

Here are the engine limit charts: 

 

If you follow them, your engine should survive without issues.

 

 

One question though, do you experience engine issues when taking off? If yes, did you warm the engine properly before taking off?

Edited July 19, 2021 by razo+r

[grafspee]

at 2500 you are limited to 42" if you push more engine will be dead soon

[Bozon]

2 hours ago, razo+r said:

Here are the engine limit charts: 

 

If you follow them, your engine should survive without issues.

 

 

One question though, do you experience engine issues when taking off? If yes, did you warm the engine properly before taking off?

 

OK, so according to the thread linked above, the problem is that I spend too much time between 42” and 52”, which is limited to 15 minutes.

 

But what does that mean? 15 min total for the entire sortie? Like a timer ticking down? Or is there a cooldown?

i.e., If I climb for 10 minutes at 52”, then cruise 10 minutes at 42”, do I have only 5 minutes left to use 52” again, or more?

 

1 hour ago, grafspee said:

at 2500 you are limited to 42" if you push more engine will be dead soon

not according to the table linked above

There it is:

 

 

[razo+r]

Yes, I think it's like a cooldown. After having used up the time period, you have to wait a bit and then you should be able to use it again (Don't quote me on that though).

 

And no, according to the chart, max MP for 2550RPM is 42''. If you are using 52'', you might be overboosting your engine, which will eventually lead to the destruction of it.

[grafspee]

at 2550 you can push 42.5

27 minutes ago, Bozon said:

OK, so according to the thread linked above, the problem is that I spend too much time between 42” and 52”, which is limited to 15 minutes.

 

But what does that mean? 15 min total for the entire sortie? Like a timer ticking down? Or is there a cooldown?

i.e., If I climb for 10 minutes at 52”, then cruise 10 minutes at 42”, do I have only 5 minutes left to use 52” again, or more?

 

not according to the table linked above

There it is:

 

 

For 2550 you can push 42.5"

What does mean that you spend most of the time between 42"-52" this is not complete information

 What was engine's rpm in that time.

If you run 2700 rpm while using 42-52" that is ok you can go like this for long time before engine fails.

If your engine rpm are 2500 at the time, then pushing 52" you seriously overboosting your engine, it leads to detonations and this in most cases ends engine life quick.

Army ask Plane's producent that engine has to last 300 hours before major overhaul or replace, so factory says ok, here is your power charts if you stick to this you will get 300hours.

It is not like that 16 min at 52 2700 rpm and your engine cracks in half.

The most important thing is to not over boost engine, due to nature of aerial engines, supercharger and turbocharger are way more capable of exceeding safe limits for engine ending up in quick engine life time.

Edited July 19, 2021 by grafspee

[Bozon]

@razo+r @grafspee

Thanks, I see.

So, to sum this up with simple thumb rules:

1. Normal operation: keep 2550 rpm and do not exceed 42” (stay in the green).
2. When needing more power (go beyond the green), first adjust to 2700 rpm, then up to 52”. Should be able to operate like this for extended periods (combat).
3. Push up to 64” (with water) for short bursts only after #2.
4. Going back to normal: reduce map to 42”, then 2550 rpm.

I’ll try to follow this and see if I continue to force-land my Jugs on hedgerows all over Normandy…

 

p.s.,

these forced landings really made me appreciate the details on this map. My last engine cut brought me onto a farm. There was an ancient tractor parked there, and when I opened the canopy I could hear birds sing. 

Edited July 19, 2021 by Bozon

[grafspee]

Yep, that is just right

[Jafferson]

I did some testings a while ago, was able to run with military power without engine damage literally forever.

Seams like there is a 15min detoration counter as soon Water is injected.

No matter how you use the 15min, 3x 5min with cool down in between, or 15min in a row. The engine will die 100% when time is counted down to 0.

If I remember right, with immortal the bird had a quantity of water for 30min. But the engine die after 15min anyway without immortal.

There is no way to reset the detonation counter with a cool down or a repair. Refuling Water dose not work too.

The only way is to do a respawn.

It's a throw away engine after a use of 15min.

 

Wish we had cool down time to reset the counter, and the ability for repair and refule.

Edited July 27, 2021 by Jafferson

[grafspee]

Watch carb temp, at high MP you will be limited by carb air temp. Cool down timer is not a good solution. Once engine picks up damage it will stay that way.

I used to run water for 10 min, it was couple patches ago something could change.

 

Edited July 27, 2021 by grafspee

[Jafferson]

5min of Emergency Power means, engine can run 5min without taking any damage.

Engineers would never allow water injection if the engine dies after a total use of 15min.

 

Looks like DCS simulates engines at the very end of there Lifetime, or the damage model is way to fragile. All WW2 birds in DCS got similar problems.

[grafspee]

There is similar thing in P-51 once you engage WEP engine seizure violently even after engine was shut down. It may have been changed recently.

I will do my tests as well, i will make sure to keep oil, carb temp in limits in those tests.

Using WEP for longer then 5min should not kill engine as well, no one can set those limit precise if it comes to wear typ of damage.

With MAP you can get quite close to the limit, but time limit will be always bind to expected life time of the engine. 

Not sure how it was with P-47 but in case of P-51 plane had to have special clearance for WEP use, i think plane's with engines with high work hours scored were excluded from WEP.  

Edited July 27, 2021 by grafspee

[Jafferson]

Got some news from my last test 

P-47 got Water for 15 minutes, i managed to empty the tank with max RPM and 60MP + Water injection at 6000 feet without engine damage :)

Top speed was 305 knots TS.

Still unabel to refule Water by groundcrew :(