I think the Supercharger is working just fine. DB601A Full throttle height is around 5000m according to most sources. Propeller Pitch in AUTO is a function of throttle lever position. As to RPM and ATA the 2 are effectively the same below Full throttle height as in general terms Throttle position determines or is directly linked to ATA and therefore RPM . Above Full throttle height that is obviously no longer the case as ATA reduces since the supercharger has reached its max output.

Here is a burst from "Schwarzeman" who has restored a number of DB engines and knows these things inside out He is a pilot as well. Its DB605 specific but the principal is the same:

"High altitude- above rated altitude(5.7km/605A) the ATA will reduce in relation to further climb, the U/min will stay the same (until the throttle is moved) and the prop clock will stay the same (until the TAS is changed)"

So what happens in COD at the moment ?
Start at 4800m Max ATA Prop AUTO 1.34ATA at say 250KMH then climb. I see ATA start to reduce at 4800m indicating Full throttle height (Supercharger at max output). As I continue to climb ATA is reducing but RPM remains 2300RPM. I continued the climb to 6000m ATA reduces to 1.1 but RPM is still steady at 2300RPM. As I climb at constant IAS (increasing TAS) I see the Prop clock fining (slight clockwise movement) to maintain the 2300RPM. So that to me indicates Throttle position is determining RPM in COD. This behaviour looks correct to me and replicates what Schwarzeman states pretty well, though I haven't documented the relationship of ATA drop off with Altitude above Full Throttle Height. (I will test this though :).

EDIT:

ATA DROP OFF ABOVE FTH
1.34 ATA 4800m
1.2 ATA 5400m
1.1 ATA 5950m
1.0 ATA 6550m
0.9 ATA 7100m

So ATA reduction above FTH is around 0.1ATA per 500m

That agrees reasonably well with the RAE test data from AVIA 6/9352 "Performance tests on a Me 110 and a Me 109E (DB601 engines)

http://img11.imageshack.us/img11/1281/atavaltsmall.jpg

Edited my first reply with the ATA v altitude drop off data.

The supercharger in the DB601A was continuous type thing through a fluid coupling (as I recall which means its output was continous up to FTH). At Sea level its doing very little work but as you climb it works progressively harder maintain the ATA. However it can only work so hard eventually it gets to its max output that becomes Full throttle height thats around the 5000m. That is exactly what I am seeing.

The Flight test I did was on the Steppe map Full throttle Prop pitch AUTO max ATA (non WEP). The numbers recorded exactly as shown on the climb. So the indications look good to me. What we dont know is the Power output going to the FM.

Cheesehawk you said:

"After this point, the ATA quickly drops to about 0.8 at 6k, and the prop pitch coarsens to about 1500rpm."

I am not seeing anything remotely like this I have done it 3 times with identical results. I suggest you repeat the flight test exactly as I did it and see what
Attached file is the single mission I was using for the test. Has you starting at 5000m. Test offline in a dedicted test environment. Who knows what has gone on previously On line. .... You might have thrashed your engine getting to 5000m :)

You also said:
"From my understanding, the AutoPP would adjust the prop based on throttle position, so it shouldn't have been coarsening the pitch when the air pressure dropped."

Its a function of TAS. Thats why in MANUAL or in the E3 in a constant IAS Climb at constant ATA you need to vary the prop to hold the RPM. Above FTH the throttle is firewalled the only variables in the climb are ATA and TAS .

Cheesehawk you said:

"Seems though, that the supercharger effect is disappearing too quickly after 5.5k or so"

Its dropping off in the Sim at the same rate as the RAE Test data. Once you get to Full Throttle height the supercharger is effectively out of the loop in terms of maintaining any further impact on Boost drop off. Its done its job in maintaining the boost at sea level values up to FTH, after that it cant do any more....its running at 100% output. The rate of ATA/BOOST drop off is then pretty much constant ... at a similar rate to a non supercharged engine as it climbs above Sea level.

To get higher still with Sea Level ATA you would need stepped supercharger with a different set of ratios/speeds etc. Like in the later Merlins with MS and FS gears requiring a manual shift at MS gear FTH. Or the BMW801 that shifted itself via Kommandgerate output.

The DB601A was variable speed but only single stage. (I am pretty sure :). So at sea level its just idling, as altitude increases its speeds up, at FTH (5000m) its running 100%.

Good discussion makes us get into the books and references :)

Try the Test file I uploaded and see how you get on.

Current Steam IL-2: COD release is generally stable and Crossfire runs well with good frame-rates on my machine. However, since installing the 15866 beta-2 (and core patch) when I ALT-TAB out and then go back into the game, Crossfire performance is affected with second card subsequently showing only half the utilization of the first and very significantly degraded graphics performance... so far only a full restart of Windows will fix this, restarting the game won't.

When ever a two formations converge, there is a point where the vidio freezes for up to 3 seconds. This occurred everytime with out fail on 40 seperate occasions. When close behind an air craft spraying fuel or coolant the frame rate decreased,if this aircraft starts emitting fire or smoke frame rate decrease to almost a stand still.

This was noticed after installing the Beta 2 patch. This did not occur with the last offical patch. I never installed first beta patch.

System Specs: Intel core i7 960 3.2, 6 GB memory, GTX560 2GB vidio card, Win. 7/ 64bits

Custom ammunition belting still does not work properly. For example, with a custom weapon set and gun belting saved, select a quick mission. Then check to make sure your weapon set is selected for the plane. Next visit the loadout screen and you will see all looks well. But during the mission itself the belts are not as set (I think convergence is ok, although the values are still reversed if this hasn't been fixed).

This was found by using a belting for the 109 where the tracers were staggered instead of fired at the same time. Using this belting I could see that it wasn't being applied when flying a quick mission, but was being applied when it was specifically selected in the FMB.

Secondarily im not sure there is any in game difference between the "weiss" and "gelb" tracers for the german planes. I think they are supposed to be different colours.

Well, thats a new one. Glad I don't get it...

Mirror problem
 

When switched off, the mirror reappears as an almost blank shape.

It may be associated with the low sun (and therefore may be a shadow issue).

56RAF_phoenix

New patch slowed frame rate,still has microstudders,Xfire not working both ATI cards.(Ubi logo disabled ,Anti Epi filter off).
Applied the small anti freeze on explosion patch to the beta then clod exe would no longer launch the game.After verifying files to roll back to previous alpha via steam clod exe would not launch the game.Uninstalled and re-installed via steam clod exe would not launch the game.
Uninstalled Clod and steam from system and cleared the registry.
Re-installed Steam and Clod and now running 1.02.14821.
PLEASE NOTE:THE FIRST UPDATE YOU RELEASED THAT ENABELED XFIRE WORKED BRILLIANTLY FOR MY SYSTEM (ACCEPT FOR MICRO STUDDERS)BUT THE SMALL PATCH RELEASE THE NEXT DAY SCREWED IT UP.


System Information
OS Name Microsoft Windows 7 64 bit Home Premium
Version 6.1.7601 Service Pack 1 Build 7601
System Type x64-based PC
Water Cooling (CPU & GPU`S)
Gigabyte GA-890FXA-UD5 BIOS Version/Date F6, 24/11/2010
SMBIOS Version 2.4
Processor AMD Phenom(tm) II X6 1100T Processor, 3817 Mhz,
RAM 8.00 GB 2x4GB 1600mhz Corsair Dominator
Vertex 240GB SSD Hard drive
1xSeial DVD reader/writer
2xATI Saphire 5870 OC Vapour X
Steel series USB soundcard & Headset
Saitek X52 PRO
2xThrustmaster MFD`s.

since i have in stall the last patch i keep get frame freezing and and the the longer i play the game it get to a point it freezers up my game and crashes my PC. The frame are good till i meet up or try and dog fight with another aircraft. I have i had to drop my game video from high to medium to make the game playable.