Intelligence report on the Daimler-Benz DB 603 aircraft engine from Informational Intelligence Summary, Office of the Assistant Chief of Air Staff, Intelligence, Washington, D.C.
GERMAN DB 603 ENGINE
Recent examinations of several DB 603 engines have revealed details hitherto unknown. The DB 603 engine, it will be noted, is used currently in the Me 410, the Do 217M, possibly as “doubles” in the He 177, in the new type FW 190 and probably in other new type German aircraft.
1. The general characteristics and specifications of this engine are presented below:
a. Type: 12 cylinder inverted “V”.b. Bore: 162 mm (6.38 in.).
c. Stroke: 180 mm (7.09 in.).
d. Piston displacement: 44.5 liters (2,720 cu. in.).
e. Compression ratio: 7.1 (possibly increased when 100 octane is used).
f. Impeller diameter: 295 mm (11.61 in.).
g. Supercharger drive: Fottinger, hydraulic compressor; basic gear ratio 9.22:1.
h. Length: 85 in.
i. Width: 30 in.
j. Height: 26 in.
k. Dry weight: 2,120 lbs.
2. Power Out-Put: A preliminary estimate of the power out-put of this engine at maximum emergency rating, using 87 or 100 octane fuel, is given in Table I.
TABLE I Altitude (Static)
ft.B.H.P. (Max. Emergency) Using 87 Octane Fuel Using 100 Octane Fuel S.L. 1,725 1,975 7,200 1,900 2,100 20,000 1,600 1,825 30,500 1,100 1,275 It is probable that these emergency ratings are accomplished with 2700 r.p.m. and 1.42 ata manifold pressure.
3. This engine is the largest known to be in operational use in the G.A.F., and in many respects is similar to other Daimler Benz types. A few noteworthy points concerning this engine follow:
a. The crankshaft is carried on seven double-row roller bearings. The lubrication system of these bearings is of the non-pressure type, an unusual feature on a modern engine.b. The spark plugs are fitted, one on the inlet and one on the exhaust side of the cylinder block, this being the first recorded instance of this location being employed in DB engines.
c. The firing sequence has been altered as compared with previous engines.
d. Two identical flanges are provided, one on the starboard and one on the port side of the wheel case at the rear of the engine, complete with all necessary oilways. This would permit the fitting of a supercharger on each side, as would be necessary on a side by side “double” engine. It is believed the DB 603 arranged in this fashion is known as the DB 613, which may be fitted on the currently-operational model of the He 177. These flanges also permit the fitting of a 2-stage supercharger with intercooler. A notable increase in performance at altitude would be obtained by this procedure.
