Are engine limitations purely temperature based?

Are all the limitations for the time you can run the engine at high power purely temperature based or is there another factor? I've noticed at times during a high speed chase at full power the temperature is still relatively low due to the airflow but im worried there is another limit.

Another quick one. Is 3000 rpm gonna give me the highest speed in level flight?

Cheers

Are all the limitations for the time you can run the engine at high power purely temperature based or is there another factor? I've noticed at times during a high speed chase at full power the temperature is still relatively low due to the airflow but im worried there is another limit.

 

Another quick one. Is 3000 rpm gonna give me the highest speed in level flight?

 

Cheers

There are other limits.

3000 rpm wont give you max speed in level flight.

No war time test were conducted at max MP and lower rpm than 3000.P-51 manual is pretty clear that WEP rating can only be used at 3000rpm.

But in DCS it is possible to drop rpm to 2700-2800 while running 67", to gain extra speed, for me its is not realistic.

I was trying recently to kill engine by running 67" and as low rpm as possible. And my engine didn't want to die in classic way of sudden seizure, so there is some work done in engine damage modeling now.

I am on Open Beta version, Stable version is much different now.

Time limitation for example military power 61' at 3000 rpm is simply amount of time which will not impact designed engine service time.You can run those engines at those rating much much longer i would say that 1h is possible, but this will shorten service time of the engine.

No it isnt realistic and that needs to be changed

Last time I tried, many versions ago I admit, pre-ignition / detonation failure from running low RPM high MAP was also modelled (though one had to enter a certain combination of these), killing the engine in about half minute (depending on ambient temp as well).

With this last update they made a major change with the engine and coolant temperatures. Before the last update you could takeoff with the coolant doors set in Auto and use max RPM and Manifold Pressure with no problem.

If you do that now the Coolant Temp will be in the red before you get the gear up. You now need to open the radiator door all the way 15 seconds on the switch and do not go above 3000 on RPM and 50 on Manifold. Our group has found running both temps below the green zone is always better than running near the red. As such we now do not use the Auto Settings anymore which use to work.

With the way things are working now you will need to always keep one eye on both of the temperature gauges.

rpm to 2700-2800 while running 67"

It used to do exactly this in another sim I shall not name many, many moons ago as well. A funny coincidence I'd say.

In my experience in RACING the DCS Mustang since 2013, there does seem to be a stress factor involved as well as the temperature modelling, though this seems pretty inconsistent and is hard to nail down. I have better reliability of the engine if I set it to my race settings (2700 RPM / WEP on for 67 MP) and leave it alone, then if I try to continually tweak the RPM's throughout the race. If at those settings, without carrying the speed in which you get the most value out of it, places more stress on the engine, and I see more failures that way.

At other times, trying to prove the point of stress, I can manipulate the RPM from minimum to max, harshly and the engine will not break. So, from this, it seems more of a random factor, loosely tied to the stress placed on the engine from extreme settings.

To the comment about needing full open radiator on take off with max power and rpms, can only say ambient temperatures might play heavily into that. I have taken off with 67MP and 3000 RPM with radiator on auto, also manually set to near closed, just fine. Cant remember exactly, but I believe the weather was set somewhere in the 60-70F degree range.

Your mileage may vary. Using those "race" settings in combat have a limited use, since the reliability of the engine drops sharply.

Though there are some damage model changes between release and open beta, the base performance of the mustang has remained the same for many years now in my experience.

About coolant temp in take off conditions,

Ambient temp is very important but direction of the wind is very important too.

When you take off with tail wind you will get very high temps.

Ok. Thanks guys, very informative. So if I get this right, 2700ish rpm for max speed and engine management is a voodoo art. :thumbup:

To a point, yes, the real manipulation is manually controlling the coolant radiators to minimize the drag they create and riding the upper edge of the temperatures, just low enough to keep it running, for racing anyways. In combat, you usually have many other things to be looking out for than monitoring your temp gauges.

The RPM thing was discussed on the other games forums and there were all sorts of theories between engine temperatures, Prop efficiency, reduced drag and mach effects as for why it works better. Seems to be the same in that game too.

Would be interesting to know why it is. Maybe Yo Yo can comment on it. My understanding is that its only a benefit at or close to top speed though, in other flight conditions (dogfight etc etc) you get better power at full RPM.

The RPM thing was discussed on the other games forums and there were all sorts of theories between engine temperatures, Prop efficiency, reduced drag and mach effects as for why it works better. Seems to be the same in that game too.

 

Would be interesting to know why it is. Maybe Yo Yo can comment on it. My understanding is that its only a benefit at or close to top speed though, in other flight conditions (dogfight etc etc) you get better power at full RPM.

That matches my experience as well. only helps in top speed. As previously mentioned, trying those settings at lower speeds seems to stress the engine more, resulting in more failures.

The RPM thing was discussed on the other games forums and there were all sorts of theories between engine temperatures, Prop efficiency, reduced drag and mach effects as for why it works better. Seems to be the same in that game too.

 

Would be interesting to know why it is. Maybe Yo Yo can comment on it. My understanding is that its only a benefit at or close to top speed though, in other flight conditions (dogfight etc etc) you get better power at full RPM.

I have no big issue that speed is going up at lower rpm, beside all of that you mentioned there is one thing, engine at 2700 rpm will produce less power then at 3000 rpm.

My problem is that engine can run at 2700 rpm at 67" with no problems, i have feeling that engine will brake less likely when running 2700 rpm then 3000 rpm. At lest it was some time ago, i didn't test it recently.

I will add, that racing p-51 often are using 3250 rpm for race. not 2700 rpm.

Again, in my experience, the lower the RPM from 3000 at 67 MP, the more likely the engine will fail. Down to 2700, those chances do not rise very significantly, below that, the failure chances ramp up significantly. Also, around and below 2700, the MP DOES start to drop. Other factors like current speed and G'loads also seem to play a part when operating in those extreme settings.

Should this be happening sooner? Maybe, but I do not have the data to refute that. I use what is provided to me and it has been this way since 2013 at least.

The risk of overboosting was discussed there as well. Someone metioned a story of a P-38 pilot who flew a sortie with the RPM way lower than recommended for a certain manifold pressure cause he believed it would save fuel. When he landed he still had plenty of fuel leftover whereas the rest of the squadron landed more or less on fumes.

The mechanics asked how he did it and when he answered they were furious, believing hed ruined 2 good engines. They tore them apart for inspection and found nothing wrong with them.

So apparently its not so simple to figure out exactly what will happen with weird engine settings sometimes.

when going up the scale you should increase RPM and then increase boost.

when going down the scale you should reduce boost then reduce RPM.

for best engine longevity and prevent over boosting.

which would explain why keeping the boost and reducing RPM makes it more likely to fail.

i saw a documentary years ago that said it was charles lindberg who figured out that running the p-38 low rpm, high boost, lean mixture and high engine temps increased fuel efficiency.

apparently he went over to the pacific at the request of the army. as a civilian

he actually flew in combat.

The risk of overboosting was discussed there as well. Someone metioned a story of a P-38 pilot who flew a sortie with the RPM way lower than recommended for a certain manifold pressure cause he believed it would save fuel. When he landed he still had plenty of fuel leftover whereas the rest of the squadron landed more or less on fumes.

 

The mechanics asked how he did it and when he answered they were furious, believing hed ruined 2 good engines. They tore them apart for inspection and found nothing wrong with them.

 

So apparently its not so simple to figure out exactly what will happen with weird engine settings sometimes.

It is not only over boost problem. And detonation isnt acquainted only with overboost.

Combustion chamber temp play big role here.

P-38 case was simply running high boost for low rpm but it was more like 2000-2200 rpm and max cruise boost.

BTW P-38 had extreme problem with detonations, Manufacture company was struggling with establishing military power for this bird.

The temperature on the server is a constant +20C. We had no problems the Temps until this last update we just received in DCS. None of which was listed along with the nav lighting fix for them showing through the wing panels. And the new ammo type selections. So someone at ED is behind the scenes working on this plane. It is my hope they do not stop correcting the issues this plane has had for a LOOOONG time.

Now if they would just slip in 150 fuel I would be a happy camper..... Fighting the K4 could be a more even fight with a little extra HP

Just took off in 23C temps in a P51, was at warmup temps, radiators on AUTO and the main coolant door was fully closed before throttle up. Throttled straight up into WEP (67 MP) and took off. Temps got up TO the redline, but stabilized and all was fine. No different than what I have experienced in the past. /shrug

Edit: And yes, on today's OB version.

Ok, just did a 2nd test, this time with a nearly full loadout on the mustang, 65% fuel, 6 rockets and 2 bombs.

Same take off conditions, this time the temps DID go over the redline a bit, nearly maxing out. But I stayed level and got the airspeed over 200 and temps stabilized. 200 mph is really a critical speed in keeping the cooling in line. Get under that and yeah, there will be cooling problems. But again, it has been this way the whole time I have flown the mustang (since 2013).

Does warming up the engine have an effect on engine reliability over a single mission? Seems like its more a longterm wear and tear issue which doesn't really affect us ingame.

I always run everything in auto and never had an overheat issue on takeoff, that been said I never warm the engine.

Does warming up the engine have an effect on engine reliability over a single mission? Seems like its more a longterm wear and tear issue which doesn't really affect us ingame.

I always run everything in auto and never had an overheat issue on takeoff, that been said I never warm the engine.

Full warm up isn't required, but minimum take off conditions must be fulfilled which is,

15 C oil min

60 pounds oil pressure min

60 C coolant.

Below this temps, there maybe a problem with proper engine response on throttle movement.

By single mission, do you mean like per sorte? Go out once, then rearm and refuel for another? Then yes, the effects are cumulative. But if you exit the aircraft and respawn it even, or restart the mission, then no, nothing carries over. You always have a fresh aircraft whenever that aircraft is spawned in.

By single mission, do you mean like per sorte? Go out once, then rearm and refuel for another? Then yes, the effects are cumulative. But if you exit the aircraft and respawn it even, or restart the mission, then no, nothing carries over. You always have a fresh aircraft whenever that aircraft is spawned in.

That would be nice idea, when wear of the engine would be saved somewhere and assigned to IP.

As an option for combat servers. With limited number of aircraft per player.

Flying at the very edge is difficult during combat as we can only rely on the P-51 temp gauges. Trying to keep eyes on a small BF-109 and at the same time glance down to check temps is a good way to loose a fight.

While it might be difficult to fully simulate, we should probably hear that something is not running ok. There might even be some smoke after a while. Performance degradation etc.

The problem, as I see it, is how the engine damage is represented in DCS. The unrealistic CLONK! sound with the propeller seizing. Instant death. Even Nick Grey stated in an interview that it is "rubbish".