[camber]

Thank you Kurfurst for the helpful reply and Holzauge for the extra calculation info.

Originally Posted by Kurfürst

Yes of course there were a lot of 109E's that just passed the minimum specs and were still accepted into service. So were Spitfires and Hurricanes. So why should be 109Es modelled after the worst possible specs instead of the nominal/guaranteed/tested and confirmed specs, while Spitfires and Hurricanes get special treatment and are modelled in optimistic conditions? Especially as the CLOD engine models wear of the airframe, so worn/badly manufactured planes and the scatter in performance can be easily modelled...?

This is a good point, made critical by the fact of having a single aircraft cloned exactly across the whole battle theatre is rather unhistorical really. My position is that the (may he exist) CloD FM czar should make a good faith attempt to find an "average" performing variant (which will always incorporate some subjective calls), then fiddle within plausible historical performance ranges to make CloD work best.

With the 109E, my position is that based on what flight testing/ etc. information is available, at 1.3ata the SL performance was around 475kmh. This close pass/fail performance on the Messerschmitt chart was however not an issue because the acceptance was based on an altitude performance test, where the typical 109E was close to the guaranteed average spec. I think we maybe overstate how important SL top speed was to the Luftwaffe of the time, as they were overwhelmingly interested in altitude performance, where the 109 performed inspiringly. In CloD however we like to chase each other just above the deck a lot more, I suspect.

Originally Posted by Kurfürst

The Spitfire II analouge is limping, since it essentially says that if the performance doesn't match the engine outputs, decrease the engine output until it matches the wrong speed. It's akin to say that if Spitfire speeds do not match the +12 performance levels, but they match the + 6 1/4 boost, simple set the gauge to show 6 1/4 (which is unfortunately the current situation in the sim). Moreover the Spitfire I / II had only one type of engine fitted (M III or XII).

I agree, the situation is a bit theoretical anyway because FM fine-tuning may not occur anyway in CloD. I do think (if we had to choose what was fixed) that it is better to have the aircraft end performance historical with wrong boost indications, rather than correct performance but for an unhistorical boost. Which brings us to the next point, about what boost the 109E SHOULD have:

Originally Posted by Kurfürst

The Me 109E in contrast had at least four fitting and used during the Battle of Britain, with different boost and outputs.

The DB 601A-1 with the old type supercharger, 1.30 ata for five min and 990 PS, and 1.40 ata for 1 min and 1100 PS. Rated altitude being 4000m.

The DB 601A-1 with the new type supercharger, 1.30 ata for five min and 990 PS, and 1.40 ata for 1 min and 1100 PS. Rated altitude being 4500m.

The DB 601Aa with the old type supercharger, 1.35 ata for five min and 1045 PS, and 1.45 ata for 1 min and 1175 PS. Rated altitude being 3700m (altitude output was otherwise very much like the DB 601A-1 / old s/c, though it is an open question wheter the new s/c was fitted to the Aa as well. So far no evidence to that though.)
This is the type we have in the sim.

The DB 601N, 1.35 ata for five min and 1175 PS. Rated altitude being 4800m. (there was a second type of 601N, mounted in one in the 109F had better supercharger and IIRC 5200 m rated altitude)

Therefore, it is pointless to compare our 601Aa equipped Emils performance (1.35ata) to real life tests of DB 601A-1 equipped Emils at 1.3ata. It should of course match the real life DB 601Aa at 1.35ata (V-15a, Baubeschreibung "5%" specs, Swiss trials of serial no. 2404)

This is a really interesting point. Googling back, I see the DB601Aa is a bit controversial in discussions going back a long way, in that is it just only an export version, or was it widely used in Luftwaffe 109s. As you say, CloD seems to have put a DB601Aa in every 109E on the channel coast, which seems an odd choice but not a demonstrably wrong one (like a Me262 Jumo jet engine would be ). If I was CloD FM czar, I would consider re-engining all 109s to one of the DB601 A-1 variants and giving it 1.3 ata 475kmh/560kmh performance. If I stuck with the 1.35ata DB601Aa, I would increase speeds by an appropriate theoretically derived increment from the extra 0.05ata (e.g. using the formulae Holzauge provided), thus using the 1.3ata 109 data as a baseline.

Going on to the extra boost:

Originally Posted by Kurfürst

The 109's 1-min Startleistung of 1.45ata worked different from the Spit II gated boost: like the Spitfire I, it had an automatic boost control which maintained 1.45ata up to near rated altitude. The primary difference was, evidenced from the DB 601Aa power curves is that just above the 1st supercharger speed, the power output with the 1 min rating suddenly dropped quickly, and although it still brought some very marginal power increase.

(snip)

So there's not much wrong with the 1-min rating being usable up to FTH, what is wrong is how it's modelled. At low altitudes, it should bring a MUCH more noticable boost in power than currently, given that it boosts the engine by 110-130 HP, but above ca. 1.5 km it should amount next to nothing (with fuel consumption still being sky high).

That seems reasonable to me, provided the 1.45ata FTH is reduced to the correct level (below 1.35ata FTH) for the supercharger capability. Right now in CloD the 1.45ata seems to be still working when around the 1.35ata FTH (without changing rpm). The one thing that concerns me is that I haven't read reports of 109 drivers reaching first for their clockwork boost buttons when in a sticky situation, in the same way RAF drivers went straight for the boost lever or tit.

Cheers,
camber