Ta 152-H1 - ATA control

[R33GZ]

Flew the Ta 152 for the first time today. Bought it on the recent sale and got to fly it on CB Mitchells Men. Great map to fly the bird on.

 

Holy Jeebus does that thing like to climb. I noticed though, that, I couldn't achieve the spec'd RPM and ATA combinations. I'm guessing they are measured at sea level maybe? I was flying mostly between 7 and 10km and noticed the ATA gauge reading 1.8 when only at 3000 RPM or lower. It fluctuated with altitude and the auto supercharger(?) but was consistently quite a ways out of spec. The RPM was solid, and I guess the speed at which the crank shaft is moving is more important than pressure; so the flight was successful, a shed ton of fun, and 3 bombers for the trouble sir.

 

Just wondering why the ATA seemed to be off spec, or was I just flying her wrong?

[MaxPower]

In my limited knowledge on the subject, I think the supercharger should be trying to hold the manifold pressure at a constant pressure for a given power setting while below critical altitude of a supercharger gear.  At the critical altitude, the pressure should start falling off until the next gear is engaged.  Then, while below the critical altitude of the next supercharger gear, it should stay constant again.  I think the Ta-152 has 3 supercharger gears, so there should be two bands at certain altitudes where the pressures are not at max.  I think the exact altitudes depend on your airspeed.  If you're going slower, the supercharger critical altitude is a little lower.  This seems to be how the other Focke Wulfs behave in the simulation.  I haven't had much time in the Ta-152 to notice anything wonky.  It'll be interesting to hear if anyone else has noticed something out of the ordinary as well!

[MaxPower]

On 5/31/2025 at 5:36 PM, R33GZ said:

I noticed though, that, I couldn't achieve the spec'd RPM and ATA combinations.

I see what you mean.  I did some high speed tests at various altitudes and noted the achieved airspeeds and ATA combinations with MW-50 enabled.  After the first supercharger gear things get a little crazy in manifold pressure land.

For the tests I used the same test methodology as CountZero in to get his IL2 Compare data.  I just did a little extra work to find the supercharger critical altitudes and gear switch altitudes.  I found that the aircraft is a bit slower than the specification sheet claims, but I'm unsure of the conditions of the test that produced the specifications.

When I graph it, the high altitude speeds look very noisy.  I'm not sure what that could be about.  But, the ATA measurements are straight off the gauge in the cockpit so there shouldn't be any methodological problem there.
 

Ta-152 Speed Tests

ALT     ATA     IAS     TAS     NOTE
0000    1.8     573     573
1000    1.8     563     591
1745    1.78    556     606     First Speed Critical Alt
2000    1.715   548     605
2550    1.62    536     599
2610    2.04    536     610     Second Speed Start
3000    2.04    531     616
4000    2.07    519     635
5000    2.1     506     653
6000    2.12    505     688
6320    2.12    491     681     Second Speed Critical Alt
7000    1.8     479     690
7080    2.5     470     681     Third Speed Start.  2.5 is the MP gauge maximum (not great, not terrible)
8000    2.5     454     693     Coolant Temperature Warnings
9000    2.5     435     705     Coolant Temperature Warnings
9250    2.5     437     719     Third Speed Critical Altitude.  Coolant Temperature Warnings
10000   2.3     414     713     Coolant Temperature Warnings

 

Edited June 9 by MaxPower

[R33GZ]

On 6/9/2025 at 6:40 PM, MaxPower said:

After the first supercharger gear things get a little crazy in manifold pressure land.

Yeah, sure does. Something I dont understand, is that because the Ta-152 has a unified engine control ie. the RPM, Manifold and mixture are all controlled by one lever, how is it even possible to have a static RPM, but a changing manifold pressure?

 

The specs list the following:

 

Combat - 30min   RPM - 3250   ATA - 1.51

Emergency - 3min   RPM - 3250   ATA - 1.7

Emergency MW50 - 10min   RPM - 3250   ATA - 1.8

 

How is it possible to have the difference of ATA between combat and emergency? The throttle is already at maximum, the RPM  is at 3250, there is no more travel in the control, so the ATA can only be affected by a change in altitude, or mechanically, by supercharger/Boost system. What am i missing?

[[CPT]Crunch]

Check the difference on the prop angle clock, that should be caused by blade angle change via fly weights to regulate and keep RPM's at peak and no more.

Edited June 12 by [CPT]Crunch

[MaxPower]

15 hours ago, R33GZ said:

Something I dont understand, is that because the Ta-152 has a unified engine control ie. the RPM, Manifold and mixture are all controlled by one lever, how is it even possible to have a static RPM, but a changing manifold pressure?

The Jumo 213 engine has a mechanical computer to manage engine parameters called the Bediengerat.  The inputs are the manifold pressure lever (throttle) position and other flight conditions.  The outputs are engine parameters necessary to maintain the selected manifold pressure.

 

Quote

The Junkers Jumo 213 engine comes equipped with a "Bediengerat" Engine Control Unit. It is similar in function to the "Kommandogerat" command device used on BMW-801-powered earlier variants of the Fw 190.
 

The "Bediengerat" is a hydraulic-electric mechanical multifunction integrator that dramatically simplifies engine control. While in most other contemporary aircraft the pilot had to constantly operate a slew of levers to manage throttle level, propeller pitch, fuel mixture, and supercharger stages, the "Bediengerat" takes the majority of the workload away. The pilot simply has to move the throttle lever to set the desired manifold pressure. The "Bediengerat" takes care of the rest, setting all other parameters to allow the engine to properly operate at the desired manifold pressure, given the current flight conditions.

 

The Bediengerat is a bit of a black box to us so we could hand-wave the engine behaviour.  We could also see if the Jumo 213A in the FW-190 D-9 behaves in a similar way.  As @[CPT]Crunch mentioned, the engine RPM is controlled by the propeller pitch, and the boost pressure would be regulated by the throttle, both of which are controlled by the hydromechanical computer.

Here's a chart of what I think is the engine performance of a Jumo 213E like the one found in the Ta-152 H-1.  It's not labelled, but the horsepower seems right and it has markings for GM-1 usage.  ~2050 PS at WEP with MW-50 seems about right.

My understanding of the concepts in the graph are like so:
Sonder Notleistung is "Special Emergency Power" with MW-50
Start und Notleistung is "Take off and Emergency Power"
Stieg und Kampfleistung is "Climb and Combat Power"

Unfortunately, we don't see the manifold pressure for each power setting.  But we see that Sonder-Notleistung and Notleistung both are at 3250 rpm, and Kampfleistung looks like it's at 3050.