Waste of a good engine/crying out for a better engine

[Shortround6]

Excellent points on the Hungarian and Rumanian engines. The original GR 14K had some trouble of its own. Especially oil leakages IIRC.

The big problem with GR 14K and ALL of it's derivatives was the two bearing crankshaft. The First G-R 14 cylinder engines were running in 1929 and the fuel available was more like 70-77 octane. Metals available were not what they would be in 5 years let alone 10 years. The two bearing crank on a twin row engine is simply not enough to support either high cylinder pressures or high rpm let alone both. It does allow for a shorter, lighter engine compared to a 3 bearing design. It was a competitive design in the early 30s but the lack of development potential limited it to about 1000-1100hp no matter who made it or what they fed it for fuel. You could put all the fins you want on the cylinders and heads but if the crankshaft failed it was 'game over'.

That also brings me to another point. I said before that the main problem with Italian high-powered aircraft engines was the lack of metal alloys. You seem to steer more in the direction of a lack of high-grade fuel as the main limitation to achieve the necessary boost, like the Allies and Germans could use on their engines.

It may be a bit of both. Power is air flow per minute. High rpm and/or high boost (more air per revolution of the crank) Lack of good alloys may limit the rpm of the engine, Bearing metals or strength of the crankshaft/connecting rods. If you can't use rpm and all you have is 87 octane fuel, which puts a limit on allowable cylinder pressures ( boost and compression ratio) you are about out of options, except to make really large displacement engines ( more air per revolution of the crank and low pressures).

 

[altsym]

wrong thread..

 

[CobberKane]

Kawasaki Ki-61 needed a better engine than it ever got..

My understanding is that the Ki-61 got the Ha 112 radial and became the Ki 100, one of the best Japanese fighters of the war.

 

[Dogwalker]

What would you say about the A.82? I have seen a proposal for the Fiat G.57, a G.55 with the Fiat A.82. Would that have been a possible engine for a fighter aircraft??
I assume the A.82 was derived from the A.80 and not the A.76?

Yes. But the G.57 remained a project that was never accepted by the Regia, that did not ordered even a prototype.
Actually I have to revise my previous statement, since the A .82 was actually used on a production aircraft (FIAT BR.20bis, only fifteen samples, but still a production aircraft). It was a powered-up A.80. However, with 1250ps, and the drag of a radial, it could not replace a DB.605 / Ra.1050 on a fighter. The FIAT CANSA Fc.20 instead would have drawn much benefit from it. Mysteries of the FIAT's choices.

That is very interesting, but you are very right. The P.XV was a 18 cyl, not a 14 cyl as I thought. But, I always thought the P.XV had an output of around 1,500 hp, equal to that of the P.XII. And wouldn't the P.XV still be too big for fighter aircraft?

Being essentially the same engine, the power advantage of the P.XV over the P.XII was not exceptional (similar to that of the P.XIX over the P.XI), but there was, and the rest was up to the two speed supercharger. The P.XV RC.25/60 was rated at 1650ps at takeoff and 1500ps at 6000m, while the P.XII RC.40 had 1500ps at takeoff and 1400ps at 4000m. The performance advantage in having 100ps more 2000m higher is evident.
The overall dimensions were the same of the the P.XII, and of the R.2600, which, for example, has been used on several single-engine aircrafts. It has never been used for a fighter, but the Australians wanted it for the Boomerang. Certainly, if you have the R.2800, and the gasoline to make it work, it is better to use it, but, if you do not have it, to make a good fighter with the P.XV is possible.

To give an idea, The P.XII and P.XV had the same diameter of a Bristol Centaurus. So, If a Sea Fury could do 740km/h with 2480hp, it could do 645km/h with a P.XV and 625km/h with a P.XII. Not bad for 1943 and 1941 respectively. This is higly unscientific, since I didn't take in account the power curve at height, nor the minor weight of the Piaggo engines, but is good for an orientation.

Your suspicion may well be justified. But I think the Germans must have been meticulous in their testing,

I think they were not. Furthermore the first few hundred Ra.1050 engines, as the first few hundred Ra.1000 engines, were made in assembling German parts in Italy. Only gradually, when the various parts of the engine entered in production, the Italian parts replaced the original ones. in February '43 even a prototype Ra.1050 could only widely be a German engine assembled in Italy, and even in the incredible case that the fighters tested had three Ra.1050 made assembling only the prototypes of pieces made in Italy:
1) the Germans had no way of knowing what their power was, as they did not test them at the bench, but on the aircrafts. As much as I value German testers, I do not think that they had the ability to know how powerful an engine is, only turning it on.
2) Even if the German testers had the ability to estimate the power of an engine just by looking at it, as you said, the measure would not make sense with engines made assembling prototype parts and, moreover, the test themselves would not have been consistent with the performances of standard production aircrafts.

However, I have read that there were some small differences. From the Italian wiki: "I DB 605C prodotti dalla FIAT avevano un rapporto di riduzione tra albero motore e elica diverso da quello di serie: 1:0,485 e non 1:0,593." If correct, why was this?

Those figures seems to indicate that the Italian engines could turn at even higher RPM than the german ones!
But really they had only to use different propellers. The Piaggio propellers had larger diameter than the VDM, so their optimum turn speed is slower.

And thanks DW, this is very interesting stuff !

Thanks to you.

 

[Ivan1GFP]

My understanding is that the Ki-61 got the Ha 112 radial and became the Ki 100, one of the best Japanese fighters of the war.

The Ki-100 was one of the best, but it wasn't any faster than the Ki-61-I series. The Ki-61-II should have hit a bit over 400 mph if its Ha-140 had delivered most of what was promised.

I believe the reasons why the Ki-100 was one of the best available Japanese fighters is because so little else was working right at that stage of the war. I already commented earlier about how the Ha-112 was tested as a replacement for the unreliable Ha-45.

The Ha-45 was an amazing piece of engineering but a bit beyond what the Japanese were capable of producing in a consistent fashion especially that late in the war. Consider that it was a 2000 HP engine with a small frontal area and only about 2000 cubic inches displacement. That the design was viable was proven by well serviced examples tested by the Allies. Problem was that the execution wasn't so good.

Imagine the possibilities of a DB 605D installed in a Ki-61 airframe.

So..... No, I do not believe the Ki-61 ever got the engine that it needed.

- Ivan.

 

[GregP]

Sorry DW, the Isotta Fraschini's weren't all that reliable according to recorded history. You saying is was won't change that.

Name one successful major warplane in WWII that ran an Isotta Fraschini engine.

They made 1 Ambroissini SAI 107. They made 14 Ambrossini SAI 207s. They made 1 Ambrossini SAI 403. They made 2 Ambrossini SS.4s. They DID make 467 CANT Z.501 single-engine flying boats, but it was hardly a major type. They made 2 Caproni CC.2's ... not a major type, I'm sure you will agree. They made 215 CaproniCa.313's and 3 Caproni Ca.331's, but hardly major types.

They also made 2 Caproni-Vizzola F.6's that were delayed until the Armistice by Isotta Fraschini engine development issues. In the end it used DB 605. They also made 425 Caproni Ca. 314's that were a non-factor. France made the Caudron C.760 with an Isotta Fraschini and it is not excatly successful ... they made 1. The Piaggio P.50 was built with Isotta Fraschinis and they made a total of 3.

Of course, the Savioa-Marchetti S.55 used Isotta Fraschinis in all 200 examples but were not warbirds.

I can't think of any other Isotta-Fraschini-powered aircraft. None were major types and all suffered from engine relaibility issues according to my sources, which may be in error.

The cars were very good, and I'd love to own and drive one, but they made poor warplane engines ... none were exactly successful.

 

[Dogwalker]

Sorry DW, the Isotta Fraschini's...

?
I think the only thing I said about an Isotta Fraschini engine in this topic is to nominate the Zeta among the "homologated, but not used in any production aircraft", Since it was homologated, but not used. For the rest, I talked about Fiat and Piaggio engines.
The Zeta, as the AR 135, even if homologated for aerial use, was never ordered for mass production, precisely because it was still considered unreliable (the P.XV instead was ordered, just there was not time, and the right aircrafts, to use it).
It's worth to say, however, that Eng. Baldassari, of the Caproni Vizzola, had no complaints about the engine, and although it showed residual problems of overheating on the F6Z, he believed that they could be solved with some simple changes to the cowl flaps.

My personal believe is that the Zeta was possibly a sufficiently reliable engine, but was very difficult to mount it right, since it needed an uneasy study of the air intakes and exhausts to sufficiently cool the rear cylinders.

They also made 2 Caproni-Vizzola F.6's that were delayed until the Armistice by Isotta Fraschini engine development issues. In the end it used DB 605.

Really the F6M was, first, the first Italian aircraft flying with a DB605, and after it was equipped with a Zeta.

 

[Shortround6]

Sorry DW, the Isotta Fraschini's weren't all that reliable according to recorded history. You saying is was won't change that.

Name one successful major warplane in WWII that ran an Isotta Fraschini engine.

They made 1 Ambroissini SAI 107........... but hardly major types.

They also made 2 Caproni-Vizzola F.6's that were delayed until the Armistice by Isotta Fraschini engine development issues. In the end it used DB 605. They also made 425 Caproni Ca. 314's that were a non-factor. France made the Caudron C.760 with an Isotta Fraschini and it is not excatly successful ... they made 1. The Piaggio P.50 was built with Isotta Fraschinis and they made a total of 3.


I can't think of any other Isotta-Fraschini-powered aircraft. None were major types and all suffered from engine relaibility issues according to my sources, which may be in error.
but they made poor warplane engines ... none were exactly successful.

I think you are confusing cause and effect. The fact that Isotta-Fraschini-powered aircraft were not major war types has little to do with their reliability and a lot more to do with their size and power. And a few of your examples had nothing to do with Isotta-Fraschini's reliability or lack of it. The Caudron C.760 for example ( 3 prototypes ? two that flew?) didn't begin flight testing until early 1940. Engines for a production version were very unlikely to be delivered in April or May. The Ambrossini SS.4 was a canard fighter and was no more successful than the American XP-55 and XP-56, do we blame the lack of success of those aircraft on their engines?

The entire Caproni Ca. 310-314 line was a series of planes smaller than a Blenheim and using lower powered engines.It is not really surprising they were not a major factor in the war any more than the Beech AT-11 or the Avro Anson were major players in combat roles. And sticking 700-800 hp engines on either one of them was unlikely to turn them into major players.

I don't know if the Isotta-Fraschini engines were reliable or not but this line of reasoning doesn't hold up. The P&W R-1340 engine never powered a "major" combat type in WW II and yet we know it was as reliable as a anvil.