+12 boost

[reflected]

Right now we seem to have 1939 Messerschmitts, Spitfires, and Hurricanes.

Apart fro mthe lack of Rotol Constant speed prop on Spitfire MKIa-s, there's something else: 100 octane fuel and +12 boost:

Trials were successfully carried out in October 1939 to increase the power of the Spitfire's Merlin II and III engines by raising the manifold pressure to +12 lbs./sq.in. 26 Air Ministry A.P.1590B/J.2-W. dated 20 March 1940 gives official notice that "The emergency use of higher boost pressures up to +12 lb./sq. in. is now permitted for short periods by operation of the modified boost control cut-out". 27 Also during February and March 1940 Spitfire and Hurricane Squadrons were converting their aircraft over to 100 octane fuel, which made possible an increase in engine power by raising the boost to +12 lb/sq.in.. 28a 28b 28c 28d 28e 28f 28g 28h 28i 28j 28k 28l 28m 28n 28o 28p 28q 28r 28s Combat reports show that +12 lb boost was used by the Spitfire (and Hurricane) squadrons during their first combats with the Me 109 E in May 1940 while covering the Dunkirk evacuation. 29 30 Hurricane Squadrons based in France during May of 1940 were also employing +12 lbs/sq.in. boost in combat. 31 31b

Apparently this was used even during Spring 1940, when the RAF still used de havilland props.

[Sauf]

Not again? Wasn't the last umpteeth page thread enough!



http://forum.1cpublishing.eu/showthread.php?t=19754

[ICDP]

This has been gone over a few times Reflected and I disagree, we do not have 1939 planes, in some cases they are much worse. Though the Spitfire Mk IIa is giving +12 lbs boost speeds even with +9 lbs boost showing on the guages.

Another link where some of the community are testing the AC performance.

http://forum.1cpublishing.eu/showthread.php?t=20196

[Peril]

http://forum.1cpublishing.eu/showthread.php?t=20110

[reflected]

Sorry, I must have missed the threads, and haven't read any official feedback on the issue. So, is it being looked at?

[ICDP]

It is easy to miss the pertinent threads among the others. I believe the devs are looking into high alt FM/CEM issues and would hope they are going to fix these issues also.

[Blackdog_kt]

Just as a side note, i don't think the instruments were calibrated for the extra amount of power, at least not early on in the war.

Boost cut-out probably started as an over-ride in case the automatic boost control failed, then pilots discovered it could be used to over-boost the engine. As such, it went from a backup system that was supposed to be used to maintain boost in normal operating range in case of malfunction, to a war emergency type system and instrumentation had some catching up to do. Viper2000 explains it in much more detail, possibly in the threads you guys linked.

As for the 100 octane issue and boost values, i agree it should be corrected but if the CEM is also realistic it will be of minimal tactical value. I mean, what is a minute or less (depending on the engine's temperature at the start of WEP usage) of running +12 psi boost before it gets damaged in the grand scheme of things during a sortie? If people think we'll be able to cruise around at those values they will be sorely disappointed.

Such power settings are more like what you would use when you see a 109's cannons "blinking" in your direction to command extra power for a maximum G evasive maneuver or to accelerate better, ie as a backup for when you've already put yourself in a place that you've probably lost the fight. It certainly doesn't represent any kind of sustainable power setting if it blows the engine to bits within minutes, it's just an "oh sh*t, let's get out of here" helper

[Kwiatek]

It wouldnt be minimal effect Blackdog when using higher boost. At low alt it would be huge difference beacuse it give 300 HP more to engine for MErlin III. It could be used for 3-5 minutes and it make big difference in speed and climb. It has no effect at higher alts thought.


For 109 E-3 emergency power 1.45 Ata ( 1.4 Ata for 601A) was allowed only for 1 mminut so it was very short time to use, also 1.35 Ata was also only allowed for 5 mintues - so its mean that both 1.45 Ata and 1.35 in 109 was seriously restricted by time - much more then in Merlin. Of course it was only for low to medium alts. At higher alts such boost pressure wasnt possible to achive due to lack of supercharger power.

[*Buzzsaw*]

Originally Posted by ICDP

This has been gone over a few times Reflected and I disagree, we do not have 1939 planes, in some cases they are much worse. Though the Spitfire Mk IIa is giving +12 lbs boost speeds even with +9 lbs boost showing on the guages.

Another link where some of the community are testing the AC performance.

http://forum.1cpublishing.eu/showthread.php?t=20196

Wrong. The Spit II has lower performance than an aircraft at +8.8 boost:



Image courtesy of Mike Williams Spitifire Performance site:

http://www.spitfireperformance.com/spittest.html

[Blackdog_kt]

Originally Posted by Kwiatek

It wouldnt be minimal effect Blackdog when using higher boost. At low alt it would be huge difference beacuse it give 300 HP more to engine for MErlin III. It could be used for 3-5 minutes and it make big difference in speed and climb. It has no effect at higher alts thought.


For 109 E-3 emergency power 1.45 Ata ( 1.4 Ata for 601A) was allowed only for 1 mminut so it was very short time to use, also 1.35 Ata was also only allowed for 5 mintues - so its mean that both 1.45 Ata and 1.35 in 109 was seriously restricted by time - much more then in Merlin. Of course it was only for low to medium alts. At higher alts such boost pressure wasnt possible to achive due to lack of supercharger power.

All i'm saying is that it's not IL2:1946 anymore where we can run with 110%+WEP by opening radiators every 5 minutes and lowering prop pitch because the overheat is directly tied to RPM. In the new sim there are limits and as such, WEP really means emergency power and can't be used all day long like it was in IL2:1946.

Sure, 12lb boost could save your virtual life a few times. It's just not something you can run for the entire mission if you fly at full difficulty and that's good, because that's the way it worked in reality as well.

I would still like it to get fixed and accurate according to historical data, i just don't expect any massive advantage for being able to run it for a couple of minutes during a 60 minute sortie.