Licence built DaimlerBenz V12s, what was the problem

[fastmongrel]

Another thread started me on this train of thought. What was it that meant that the licenc built DB engines never seemed to live up to the engines built by the Germans. I can find three companies Alfa Romeo, Kawasaki and Aichi that built DB engines and plenty of claims they werent as good as the original but no info on why that was.

 

[tomo pauk]

From what I can gather, the Aichi Astuta was the one with problems, Kawasaki and Italian produced engines were okay. Aichi was to produce engines for the Navy needs, the Kawasaki for Army.
The Kawasaki-own development, the Ha-140, seems to ba a problematic engine too, leading to the installation of the radial engine in the Ki-61 airframe that become the Ki-100.

 

[stona]

I've not seem it claimed that the Italian built engines performed worse than the German built ones. They were interchangeable and at least some pilot's notes I've seen give the same instructions for both (as far as I can tell with my limited Italian).
I've seen it claimed that the Italian engines had a higher output, but this is, I think, due to a misunderstanding of which version of the Daimler Benz engine was being produced under licence.

I can't comment on those built in Japan.

Cheers

Steve

 

[fastmongrel]

Spent a while on google and English language info on Japanese and Italian engines is frustratingly sparse. I am only going on fragments but it seems the Japanese models had problems with crankshafts, crank bearings and lubrication.

All the information I have found on the Aichi Atsuta V12 could be written on the back of a stamp with a marker pen.

 

[davebender]

https://en.wikipedia.org/wiki/György_Jendrassik

Hungary also license built the DB605 engine. A reasonable decision but it would have been interesting to see a turboprop powering Hungarian built Me-210C.

 

[GregP]

When I was working out at Joe Yancey's shop, we had a fellow come in who talked a bit about the Japanese version. Seems that after the war several Ki-61s made it over here and got tested by our pilots. One of the Ki-61s was being flown by one of the test pilots and had an engine problem. This particular test pilot was also a mechanic. He nade the rather unusual choice to remove the engine and look at it. What he found was that there are oil passages in the main block, but the Japanese had failed to drill a couple of them into the nose case. So ... the engine ran fine until the oil in the nose case all got returned to the tank but never got replaced. Then the engine would run for some 30 - 40 minutes while getting hotter all the time, until failure happened.

Now this tale is heresay, but should not be hard to validate, assuming one has access to an Atsuta engine. Obviously, I don't. Since that time, I have heard this same assertion several times, but no confirmation from any source.

So it sort of remains an interesting possibility that probably should be investigated, but which may never actually be so. I repeat this here for information only but don't claim it to be fact since I don't know. Whatever the reason, the Japanese were never able to field a good liquid-cooled V-12 in WWII.

I haven't ever heard or seen any big complaints about the Italian versions, but have read they generally produced about 100 or so less HP than the German versions. Why this should be is anyone's guess. I'd hazard a guess that engine plans don't exactly show all processes steps and it could be that the finish on one or more parts was simply not quite the same. In a 1,475 HP, 100 HP is significant, but not greatly so. The addition of another 100 HP in, say, a Regianne Re.2005 might have made a small difference in performance, but would never have influenced the number of them produced.

 

[tomo pauk]

I would not be so sure that Italian-produced DB 6 produced less power than it's German counterpart. The difference might lay in that the Italians (and Japanese) produced the DB 601Aa, the small letter 'a' meaning 'ausland', or 'for foreign country'. The 'Aa' was making 1100 PS, or 100 PS more for take off than the 'A', and at rated height of 3.7 km power was 1100 PS. Above 4 km, the 'A' was a bit better (all altitudes are for no ram).
The 'Aa' of German production seem to went in the fighter-bomber versions of the both Bf 109 and 110.

 

[GregP]

It's what I have read over many years, Tomo. That said, you could be right. The many items I have read on it mentioned a bit less HP, but I don't recall them dwelling on the exact model of engine the "Tifone" was supposed to be. The slightly less HP was mentioned. I may have to go back and look that up since your observation may account for it.

 

[GrauGeist]

The "Tifone" was the DB605 manufactured by Fiat as the RA.1050

 

[Aozora]

According to Nicholas Millman in Ki-61 and Ki-100 Aces https://ospreypublishing.com/ki-61-and-ki-100-aces

The first Kawasaki built DB 601A, designated the Ha-40, was available from July 1941 and by November it had passed all ground running tests. Kawasaki, however, struggled with the responsibility of developing both the engine and the airframe....The Ha-40 inverted-vee engine... was slightly lighter than the DB 601, but more powerful - it was rated at 1175 hp. Kawasaki had been unsuccessful in gaining license manufacturing rights to the DB 601's all-important Bosch fuel injection system, so it had to incorporate a Mitsubishi-designed alternative. (page 8 )
The very high pressure of the Mitsubishi fuel injection system led to fuel leakage and fuel line ruptures. The ignition system was troublesome, with poor quality spark plugs causing pre-ignition or constant fouling. Leaks in the coolant system due to poor castings caused overheating and the quality of the bearings caused many problems....
In New Guinea there were ongoing problems with insufficient numbers of mechanics and inadequate maintenance facilities....the Japanese Army had little experience with liquid-cooled engines, and most of the maintenance crews had no expertise with this type of engine.(page 16)

The Ha-140 that was supposed to power the Ki-61 II series had improved inlet flow, strengthened supercharger, higher compression and a water-methanol injection system; it suffered from excessive vibration, main bearing failures and oil leaks.

All in all, the Ha-40 and Ha-140 had potential, but both were underdeveloped. Added to that, New Guinea must have been the worst possible place in which to debut both the engine and the fighter en-masse. It was at the end of a very long supply chain, and no thought seems to have been given to having a cadre of properly trained mechanics to support the Ki-61.

 

[MiTasol]

Spent a while on google and English language info on Japanese and Italian engines is frustratingly sparse. I am only going on fragments but it seems the Japanese models had problems with crankshafts, crank bearings and lubrication.

All the information I have found on the Aichi Atsuta V12 could be written on the back of a stamp with a marker pen.

Have a look for Francillons book (Japanese Aircraft of the second world war from memory.)

I will try to dig mine out and post what is in that - not a lot but it does explain where the Atsuta name came from. The engine section is only about 15 to 20 pages long

 

[GregP]

Anyone know of a running Atsuta engine, anywhere?

 

[msxyz]

I can fill in some info regarding the italian version of the DB601, which was named RA1000 RC41. Unlike the later "Tifone" engine built by FIAT, which was more or less an exact copy of the DB605, Alfa Romeo engineers took some time to improve/adapt the engine to local tooling, materials and manufacturing techniques.

The result was an engine which was as dependable as the original (some Italian sources of the period say even more) and built using domestically available materials; it made ample use of domestically developed alloys based on aluminium/magnesium which were forged inside electric, induction type ovens. Steel, on the other side, was not as good as those available to german engine builders and that must have required strengthening and redesign in other areas.

Overall, the engine was some 60kg heavier and 180mm longer than the DB601. Power was almost the same at TO, while at altitude the italian version lost a bit more than its german counterpart. It should also be taken into account the poorer quality of the Italian fuels available at the time. Methyl was domestically produced in insufficient quantity and it was still common to use a mixture (I think it was called "Miscela A.S.4" but I may be wrong) which was gasoline straight out of the refinery blended with benzene and anydrous ethyl alcohol in order to boost the octane rating to around 85-87. It was a sort of poor man E20 gasoline minus the benzene (which is today outlawed and substituted by xylene or other less dangerous aromatics).

 

[Lefa]

Also Sweden made license Db-engine SAAB 21 - Wikipedia

 

[dedalos]

As far as i know all the series 5 italian fighters were tested and produced with their Db 605s at 1,3 ata and italian propellers which were of inferior performance than the german propellers. Were the Fiat G55, Re 2005, and C205 ever cleared for 1,42 ata? i dont know it. But the Bf109 was cleared for 1.42 ata in octomber 43. By that time italy had changed sides.I find it unlikely that in the chaos of those days any improvement was introduced.
Even with 1.3 ata all three series 5 fighters look overall better than the mid war Bf109, except the production cost and man hours

 

[msxyz]

The main difference between the Italian 'copy' of the db601 and the copy of the 605 is that the former was given to Alfa Romeo and the license was given before ww2

Not only Alfa Romeo had a better engineering teams (they had a profitable relationship with Bristol and they successfully improved their designs bringing the pegasus from 700hp up to 1000hp of the latest Alfa Romeo variants) but they improved the designs to work with what Italy had at the time. (plenty of domestically mined Zinc, Magnesium and Aluminium, but few critical metals like nickel or chrome and their steel quality lagged behind being depended on imports of coke and quality iron from Germany).

The fiat version of the db605 was done when the tide of war was changing and no time was spared to reengineer the engine. So it was a poor man's copy.

on of of that, as I mentioned before, the Italian fuel was very bad, so bad that, in one instance, a P38 Lightning captured intact wasn't able to fly with Italian avio gasoline no matter the manifold pressure.

I've read a paper by famed Nobel prize winning Italian chemist Giulio Natta, that he wrote just before ww2, proposing a method to synthetise 100 octane gasoline from methane to overcome 'the known fuel problems'. I guess he didn't have the time to sell his ideas to the government or ww2 simply come too kearly for Italy. Fuel quality and the embargo on steel hampered the Italian efforts to develop high power reciprocating engines, not lack of engineering talent.

 

[stona]

A brilliant man. Natta, but also one to benefit (unintentionally) from Mussolini's anti-semitic laws. I'm sure Natta has some reaction named after him, but it's been so long since I practiced chemistry that I couldn't say what it is. It must be important or I wouldn't have remembered the name at all

I posted in another thread about the exodus of scientists from Nazi Germany, and later and to a much lesser extent from Italy. I have no idea what happened to Mario Levi, who Natta replaced.

Cheers

Steve

 

[msxyz]

He perfectioned some catalysts that opened the door to mass production of many plastics, polymers, etc... The name of the reaction you're looking for is the Ziegler Natta polymerization.

 

[thedab]

As far as i know all the series 5 italian fighters were tested and produced with their Db 605s at 1,3 ata and italian propellers which were of inferior performance than the german propellers. Were the Fiat G55, Re 2005, and C205 ever cleared for 1,42 ata? i dont know it. But the Bf109 was cleared for 1.42 ata in octomber 43. By that time italy had changed sides.I find it unlikely that in the chaos of those days any improvement was introduced.
Even with 1.3 ata all three series 5 fighters look overall better than the mid war Bf109, except the production cost and man hours

from a book I have on the G55,the Tifone was cleared for 1,42ata in early 44.

and what your source for the Italian props being inferior to the German props?

 

[GregP]

What book, dab? Curious only.