[vanir]

Hi. I'm going to start a thread on the topic to draw some attention to it as it really affects the gameplay in IL2 for historic campaigning enthusiasts of the Me-109.

I've posted this at the Ubi forums, but have now realised Oleg has at least visited this one in recent memory.

As it is so far I've used the compare software to confirm my assumptions that at least three out of four Emils modelled in IL2 use the DB-601A-1 engine, which is kind of annoying. Firstly, what then is the point of having four Emils? Secondly it is simply inaccurate in regards to the deployment of Emils during 1941 at which time they still formed a very strong Luftwaffe fighter presence. These aircraft, E-7 and E/N(GM-1) types should have improved performance, notably climb rate and operating rpm. Also the E-4/B should really have the 601Aa engine which has a lower rated altitude and better climb rates and speed at low altitude, for a reduced top speed and climb rates at higher altitude.

What all four Emil models have is the same engine with a slightly higher rated altitude for the E-7/Z presumably to facilitate GM-1 activation at 6.5km. Performance in the E-4/B, notably climb rate is reduced to reflect a heavier take off weight (increased armouring).

Some engine modelling software like Engine Analyzer Pro can clearly show the transformation of the DB-601A-1 to the DB-601Aa through the fitment of a smaller diameter compressor casing (same impeller size), which reduces rated altitude for the benefit of higher outputs at low altitude. There should be far more clear performance differences than are modelled for the Emils.

The listed max.emergency outputs (official documentation) of the 601A-1 are 1100PS (2400rpm) at sea level and 1020PS (2400rpm) at 4500m. It can only be held for a maximum of one minute before a cool down. Normal maximum outputs are 990PS (2400rpm) at sea level and 960PS (2400rpm) at 5000m.

For the 601Aa they are 1175PS (2500rpm) at sea level and 1100PS (2400rpm) at 3700m. Normal maximums are 1045PS (2400rpm) at sea level and 1050PS (2400rpm) at 4100m. As mentioned the smaller supercharger casing meant you ran out of puff lower, even though the same internal size gives the same manifold pressures through the flight envelope.

The DB-601N engine was a tremendous improvement, involving cylinder head and camshaft profile revision in order to increase operating rpm from 2400-2500 to 2600 max. emergency rating. Whilst this would normally increase manifold pressure beyond engine tolerances, the effect of increasing the intake camshaft duration in fact reduced manifold pressure although the net gain is still increased power outputs. This engine was limited to using C2 or C3 high octane fuel, because it runs hotter than a 601A.

Outputs for the 601N are listed as 1175PS (2600rpm) at sea level and 1175PS (2600rpm) at 4900m. This max.emergency rating is believed to be historically increased for a five minute use before cool down. The normal maximums are 1020PS (2400rpm) at sea level and 1050PS (2400rpm) at 4850m.

One particularly annoying part of the E-7/Z model which definitely uses the 601N is that its operating engine speed is not increased at max.emergency/take off power to reflect the change from the 601A. This is not historical, although for the E-7/B it might be argued that many E-7 airframes were simply modified E-4/B types with the 601A engine, which is historical (similarly many E-4 aircraft were fitted with 601Aa engines and a some were fitted with 601N engines and left otherwise unchanged). The point is the E-7/Z model describes the Luftwaffe Me-109E/N(GM-1) aircraft, which most assuredly uses the 601N, of which all produced without exception, have a 2600rpm maximum take off and emergency setting.

An important point is that the 601N received a new supercharger when fitted to the 109F series airframe, which restored some of its lost manifold pressure and increased maximum output to 1200PS for take off.

According to another documented source these maximum emergency restrictions were removed during 1941, so that any 601 could use maximum emergency ratings until overheating occured. There was no longer a one minute or five minute maximum use restriction.

The later 601E of the Friedrich returned to B4 fuel use, but refined the modifications of the 601N "hotrod" engine to produce even more power. But that doesn't immediately concern discussion of the Emils modelled in IL2. The other Messerschmitt 109's may possibly be improved with more modelling attention to fine engineering details, but they certainly don't cry out for it as much as the Emil models.

PLEASE OH GOD OLEG REMODEL THE PERFORMANCE OF THE EMILS.

I'd say that about covers my sentiments.
I'm an engine enthusiast, IL2 is accurate enough in every other respect for me, but I like flight sims for the realistic engine modelling.

Thank you for your time.