Power output of DB601 + 100 octane

[Seadog]

Originally Posted by 41Sqn_Banks

As can be seen here the power of the Merlin III +12 boost at sea level is about 1190bhp (= 1207 PS) and increases to 1310bhp (= 1328 PS) at 8800 feet.
The highest power of the DB601N is given as 1260 PS.

At 5km (= 16,404feet the DB601N again has again 1175 PS, compared to the 1025bhp (=1039 PS) of the Merlin III.

At 7,62km (= 25,000 feet) the DB601N still has 850 PS (= 838bhp) compared to the 750bhp (= 760 PS) of the Merlin III.

So basically the Merlin III has slightly higher power at low and moderate altitudes (32 to 68bhp), however the DB601N has much more power at high altitudes (~90PS).

I'm wondering why the manifold pressure of the DB601N is 1.35ata, I had expected something like 1.4-1.45.

Thanks.

Of course the Merlin XII and then 45 would have shown improved high altitude performance.

[Kurfürst]

Originally Posted by 41Sqn_Banks

As can be seen here the power of the Merlin III +12 boost at sea level is about 1190bhp (= 1207 PS) and increases to 1310bhp (= 1328 PS) at 8800 feet.
The highest power of the DB601N is given as 1260 PS.

At 5km (= 16,404feet the DB601N again has again 1175 PS, compared to the 1025bhp (=1039 PS) of the Merlin III.

At 7,62km (= 25,000 feet) the DB601N still has 850 PS (= 838bhp) compared to the 750bhp (= 760 PS) of the Merlin III.

So basically the Merlin III has slightly higher power at low and moderate altitudes (32 to 68bhp), however the DB601N has much more power at high altitudes (~90PS).

I'm wondering why the manifold pressure of the DB601N is 1.35ata, I had expected something like 1.4-1.45.

It was possible to raise the RPM of the 601A/N above FTH and thus improve high altitude output by increasing revs/capacity of the supercharger, and maintain manifold pressure to higher altitudes.



The already posted DB 601N chart does not show did, though it shows the effect of RPM increase at lower settings. Based on that it would be a reasonable estimate IMHO that the power output of the 601N above 4.8 km could be increased by 100-150 PS, for example to about 950-1000 PS at 7.62 km (25k feet) by increasing the rpm to 2800.

As per Blatt 6 of the 109F-1/F-2 increasing the rpm to 2800 at FTH resulted in 10-15 km/h speed increase. http://kurfurst.org/Performance_test...1F2_DB601N.PDF

[41Sqn_Banks]

A similar increase of RPM was permitted for the Merlin III (http://forum.1cpublishing.eu/attachm...4&d=1334674718, http://forum.1cpublishing.eu/attachm...5&d=1334674727), not sure about the date though. This didn't increase the maximum power but increased power of the 30 minute climb-power.

I think the benefit of increased rpm in the DB601 could be even greater if the propeller wouldn't be operated above the best efficiency at this rpm.

Would be interesting to compare Merlin III vs. DB601A(a), Merlin XII vs. DB601N (old supercharger/new supercharger, Bf 109 E/F) and Merlin 45 vs. DB601E (Bf 109 F-4).