Hi Ivan,
In the documentation I have, the fact being that these airplanes had no fighter-plane characteristics, on their normally long bomb runs, throttles were mostly left alone after passing rated altitude.
A cruise-speed also existed, but was only a bit lower than max. speed, to allow flight in formation. This was often done with the Gotha G-planes, but not with the Giants, who usually flew individual missions, and if 2 or 3 were involved, there was no formation flying.
Not being fighters, there was no need for WEP. Neither was there a 5-minute max. take-off power because throttles were gated on the ground anyway. The pattern seemed to have been: Take off at 75% power, circle to cruising altitude, gather there if flying in formation, and then give full power to head for their destination.
They were all heavily armed, had protective plating for all crew positions, could take a lot of punishment due to their sheer size, and had no escorts. If attacked, pilots did some slow evasive manouevers but not much more, and gunners gave effective and precise defensive machine-gun fire in all possible directions.
Thus, maximum power was equal to maximum continuous power, and all had auto-mixture. There was no need for WEP or 5 minute-full power. Also, to safeguard the engines that broke if pushed beyond these limits, this was not a criteria.
This seems to apply to both Mercedes and Maybach D.IVa engines, which despite their greater power, were both not used on fighters because of their weight and slower RPM. Lighter fighter aircraft engines of the DIII class also had an "over-compressed" DIIIa high-altitude engine type, (Mercedes and Maybach) with automatic carburettors to limit low altitude power. Here there definitely was a maximum time limit for full power during combat, a maximum continuous power to head for a destination, and a cruising speed for returning home or loitering.
Incidentally, the Maybach engines were more powerful at higher altitude than the Mercedes ones, as they were more "over-compressed", in spite of being slower lower down.
So, now we have some more numbers:
Here is the 100-friction test, torque compensated for performance.
Timing Results are almost identical to the previous 80-friction test, but the balance is much more delicate;
Slight under-compensation causes turbo failure, slight over-compensation causes Hp surge and fluctuation.
Peak Hp, RPM, and RoC(FPM) at 4300 ft critical altitude is more apparent, and very noticeable during flight!Also, level-flight Hp is more exact. I like it!
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FT Alt:......500....3281...4300.....6562....9843....1 1300.....12467
KTAS..........46....48......49........50.......53. ...........55.........56
RoC(FPM)..294....308.....357......244......156.... ....113.........93
RPM........1276...1338....1388....1342....1320.... ..1307.....1300
HP............210...225......242.....202......171. .......158.......148
Min:sec..1:45.....10:40...13:40...21:43...38:25... ..50:50....58:00 >time to altitude
aim:.................11:00.............16:00....55 :00..............150:00 >available spec. times
time diff:...........-0:20............-4:57....-16:35..............-92:00 >how many sec. too fast
Lev.flight 4300 ft: 70kt 266 hp 1436 RPM -Correct!
Aim: 70kt 267 hp 1450 RPM -goal performance
500 ft: 64kt 213 hp 1308 RPM -definitely acceptable
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A slight reduction in engine-torque will prolong time to 6562 ft by another 1 minute, and to 9843 ft another 2minutes, but at 2 prices:
1) Loss of power all round, including the prominence of the peak at critical altitude.
The difficulty here is that the affected RPM range covers climb speeds both above and below critical altitude, and also level flight below it.
2) There´s lower level flight performance at critical altitude. Although this can be corrected by adjusting Zero lift Drag, it messes up lots of stuff elsewhere.
Now I´ll try out the induced drag adjustment you suggest, but I think that this is actually already quite OK now.
Cheers,
Aleatorylamp