DB vs Merlin vs ??

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Senior Airman
Aug 8, 2005
All the top engines used in WW2.

Which would you have?

What would you change?

BTW: What was the equivalent Russian engine?
The Klimov M-105P/PF and M-107A were the Russian equavilents of the RR and DB liquid cooled engine serise. They were based on the Hispano-Suiza V12 designs from the early 1930s. Also know as the VK-105 and VK-107.

M-105P put out about 13o0 hp at sea level, about 1200 at 2500 and about 1000 at 4000m. It dropped off sharply after that

M-107A put out about 1550-1650 hp at sea level to 2 km, and about 1450 at 3800m.

I am a British aviation fan so I am biased, but I would have to say its really a toss up between the two engines. Each has their own pluses and minuses. I think that the Merlins biggest advantage was in the ability to tailor the supercharger and compression ratios so easily, usually giving them a performance advantage at altitude. The DB family was much larger in cubic engine capacity (36 liters vs 27 litres) and when British engineers got their hands on a few captured DB 601s during the Battle of France they were suprised at how little power the Germans were getting out of engines with 1/3 greater capacity than the Merlin.

It's unfair to compare the whole DB601/605/603 family to the Merlin serise alone. Better to compare the DB engines to the Merlin and the Griffon, which had a similar capacity. The DB 601 is really the counterpart to the single stage Merlins (Merlin 40 family), the DB-605 the counterpart to the two stage Merlins (Merlin 60 family) and Griffon.

Invariably, its probably going to come down to personal preference rather than any shining, clear out winner. The engines see-sawed back and forth so much in terms of power advantage during the war that deciding on a conclusive answer is difficult. Generally speaking the DB-605 was superior to the Merlin 60 family at low altitudes. At medium altitudes they swapped back and forth between powerbands. At high altitudes the Merlin is generally seen as the better engine.
The Packard Merlin V-1650-9 in the P-51H was rated at 2220 hp. Not too shabby for an engine with only 55% of the cubic capacity of the R-2800. At 28 lbs boost the standard Merlin 66 was putting out about 2180 hp with 150 octane avgas ("purple passion"). Rolls Royce even got a Merlin up to 2,310 hp and 30 lbs boost in July 1943 by use of additives in the petrol.
Yes but the late war P&W R-2800 that was stuffed into the P-47 M and N models and was rated at 2,800hp could literally generate 2,800hp at 32,000ft though.
cheddar cheese said:
Fiat RA 1050 R.C.58 8)

Was there any difference between the RA 1040 R.C.58 and the DB605A-1? I don't have much information on italian engines, but there doesn't seem to be any difference in HP, so it can't have changed much, if any.
I dont think so - The RA.1050 was just the license built DB-605. They probably are almost identical; I'd look up some information on them but I dont have the time right now.
Well to be honest, I was trying to avoid discussing radials, but what the heck. :D

I'm confused as the DB605 has advantages/disadvantages that are reversed for modern car engines, e.g:

It was a square engine for WW2 - Good for high RPM's, but never saw above 3000rpm?

Direct Fuel Injection (Kugelfischer?) - bad for high rpm, but reversion is undesirable in plane engines is it?

It has things that are interesting i.e the viscous supercharger Lunatic mentioned.

How does it being inverted help handling?
Surely CG doesn't matter in the air?

- I'm outta my depth here. :oops:
Lets discuss the Napier Sabre instead!

The Sabre IIc could put out over 3000 hp at emergency overboost according to Closterman, and was fitted to or swapped into a number of Tempest Vs! :shock:
You've mentioned the Sabre before Jabber, very interesting H-configuration. 8) Unique in that respect?
For WW2 engines I think so. I can't recall any other H form engines operating in the war, though that doesn't maen there weren't any.

The Sabre had the highest output per cubic inch of capacity of any engine of WW2, suppassing 1 hp per cubic inch in 1940 and eventually getting up to 1.35 hp per inch cubic capacity in 1942 and 1.79 hp per cubic inch by the end of the war (that is over 4000 hp from a 36.7 liter (2238 cc) engine). Service engines such as a Sabre IIb would produce about 1.07hp/ cubic inch, but more in emergency situations. Closterman describes overboosting his Tempest V to 3000 hp and 13lbs boost, but this was apparently non standard and could only be done on the Sabre IIc, which had a stronger chankshaft and was tested but not officially cleared for 13lbs boost.

Closterman quote:

Thanks to its 2,400 h.p. engine it had a considerable margin of excess power and its acceleration was phenomenal. It was pretty tricky to fly, but its Performance more than made up for it: at 3,000 feet, at economical cruising speed on one third power (950 h.p.) with two 45-gallon auxiliary tanks, 310 m.p.h. on the clock, i.e. a true air speed of 320 m.p.h.; at fast cruising speed, at half power (1,425 h.p.) without auxiliary tanks, 350 m.p.h. on the clock, i.e. a true air speed of nearly 400 m.p.h.; maximum speed straight and level with +13 boost and 3,850 revs.: 430 m.p.h. on the clock, i.e. a true air speed of 440 m.p.h.

In emergencies you could over-boost it up to nearly 3,000 h.p. and 4,000 revs., and the speed went up to 460 m.p.h. In a dive the Tempest was the only aircraft to reach, without interfering with its handling qualities to any marked extent, sub-sonic speeds, i.e. 550-600 m.p.h. ""
I always thought that H style engines were problematic and unreliable? BRM tried a H format in 66/67 in F1 and it was plagued by unreliablity and lack of power...How did the Napier engine differ?
Well, I chose it because it was Italian :lol: I had a look and couldnt find anything anyway...does anyone else have any information on the two engines and how they compared?

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