Airshow Spit vs 109 - Youtube - In cockpit camera

[Blackdog_kt]

These however are the maximum permissible values for very short periods of time.
Actually running +6lbs boost is not that much lower than maximum continuous power.

For example looking at a Spit Mk.XIV/Griffon 65 pilot's handbook i have lying around, it is capable of +18lbs but only for 5 minutes (war emergency power). Maximum takeoff power is +12lbs when heavily loaded but it can takeoff with +7lbs as well, +9lbs can be used for 60 minutes on the climb out and the maximum continuous power is +7 lbs. Anything more than that will eventually heat the oil up to the point that it dissolves, lubrication is lost and the engine cooked. More or less similar limits were imposed on the Merlin engined variants as well.

This is not only applicable to the Spit, most aircraft of the time can't operate at full power for very long. For example, a 190 that is rated for 1.4 Ata at full power is limited to 1.2 Ata for continuous use, a P47 can go up to about 60" of manifold pressure but usually runs a good 15"-20" lower and so on.
Just another reason i'm eagerly awaiting SoW and a refined engine management model. No more Spit +25lbs going at full throttle for hours or 190s running 110%+WEP and resetting the overheat timer by popping the cowl flaps open every few minutes

If you want to see how much difference it makes try flying a Spit Mk.IX in IL-2 and limit yourself to using no more +7lbs, unless exceeding it for a couple of minutes at a time.

[kimosabi]

Originally Posted by Blackdog_kt

No more Spit +25lbs going at full throttle for hours or 190s running 110%+WEP and resetting the overheat timer by popping the cowl flaps open every few minutes

I'm sure there's no such thing as a "overheat timer" but I see your point. Just watch the temp gauge. I'd love to play the game in super realistic engine management mode too. WEP used ONLY in emergencies, like it was supposed to and utilized during WW2.

[Blackdog_kt]

I use the term "overheat timer" to describe in a few words how overheat usually works in IL2.

In reality, for every second spent at higher than spec temperatures you run the risk of something breaking. This risk doesn't always just go away if you throttle back, because in some cases damage could be cumulative. You could badly overboost your engine for a minure or two longer than you should and nothing would seem wrong, only to have it break down half an hour later because of a tiny crack in one of the cylinders that serves as a starting point for a cascade of damaging events.

In IL2, what we lack is the accumulation of this damage. As long as you manage to cool the engine within a certain timeframe (before you hear the engine sound changing to the sample used for damaged engines), the engine is once more as good as a brand spanking new piece delivered straight from the factory. It's like the engine "resets" to its default undamaged state erasing any previous damage and the reason is that there isn't really any damage modelled yet at that point. It has to reach the point where you see your RPMs drop and the sound sample change to actually register damage.

I hope i explained it clear enough to make sense

[Flanker35M]

S!

That was well put Blackdog. And people fly using this overheat feature(among other ways to game the game) to their advantage..well who would not when they learn it. So therefore I really hope SoW will punish you for abusing the engine over the limits, making you fly by the book on harder realism settings. Also how you operate mixture, boost and rpm should effect, there are limits for them too. We will see...

[David603]

Originally Posted by Blackdog_kt

No more Spit +25lbs going at full throttle for hours or 190s running 110%+WEP and resetting the overheat timer by popping the cowl flaps open every few minutes

If you keep the speed up then its not only possible to run until the fuel runs out but also to fight for very long periods of time on full power in the Spit 25lbs. And it is very easy to keep up speed on the Spit 25lbs, because you have just over 2000hp hauling a plane that is by late war standards very light.

Here is a scary piece of info for the Blue pilot out there

25lbs was not the most boost that a Merlin 66 could be made to use, there were also successful experiments with 28lbs boost giving almost 2200hp.

Of course, by the time this could have been made operational, there was no need, the Allies had air superiority, most Spitfire IXs were being used for ground attack, and even the 25lbs IXs were changed back to 18lbs to standardise fuel types and reduce engine wear, but it is still something to think about.