FIAT A.S.8 ENGINE.

[Dogwalker]

I begin my replies to the third critics.
Yes, there are different errors. But you tell something not supported by data or bibliography...: "As far as i know..."
I told that i found the scheme in the following article (but obviously you do not read all the text): Giuseppe Pesce (author), Motori radiali nella Regia Aeronautica, in: Rivista aeronautica, 1989, n.1, gennaio-febbraio, page 111 (table), pages 106 to 113 (article).
So this isn't my work! It's the Giuseppe Pesce work. Do you know Giuseppe Pesce? A General of the Aeronautica Militare Italiana (Italian Air Force), and founder of the Vigna di Valle Museum. You could turn your criticism to him

Infact I made a comment about the chart posted, not about you. Sorry if you have taken it personally.
whoever did it, the P.XIX was definitely service in September 1943, and, in the "experimental" section, are listed engines already widely tested, for which the Air Force had ordered the production of thousands of copies, with engines that could have been be set just on paper

About Zeta and its problems, every engine needs a development period.

I know, and personally I like the Zeta very much. Personally I believe that the most part of It's problems, as for that of the more powerful versions of the Delta, were more due to the installation on a particular aircraft (for such an engine, dimensioning and positioning of air intakes and exhausts required a more careful work than of the positioning of a NACA cowling, or a radiator, in conventional engines), that to the engine itself. But the fact remains. The Zeta still had several problems in autumn 1943. The P.XV didn't had the same problems, and was a world class engine in 1943, demonstrating that it was possible to do them, even in Italy (harder it was to prepare a mass production, the real problem in Italy was manufacturing, not of designing).

The A.30 (why anemic?) was a AS5 evolution. It was the CR30 and CR32 engine. Both excellent aircraft. And the final (unfortunately!) A.30 evolution was the A.33. Better than the contemporary A.74 or A.80. If you don't believe, you colud see the ratio between the power and the displacement (CV/L = Metric horsepower/liter).
...
You, Dogwalker, don't consider the difference necessarily due to the displacement of the engines.

I don't consider it, cause it means very little. We are not talking about a race in which there are displacement limits.
It's natural for the smaller displacement engines to have an higher specific output, but, on air, what count more is the hp output, then the hp/weight ratio, then the hp/dm2 (a lot less than the previous ones, since the drag of the engine is only part of that of the entire aircraft, and, for the inlines, the drag of the radiator is rarely taken into account). For example, if (simplifying) a Piaggio P.XII has the same power, the same weight and the same diameter of a Bristol Hercules, what does it matter if the first is a 53l engine that obtain the same power of the second (a 39l one) functioning at lower rpm? They are engines of the same class. The efficiency of an aircraft engine is measured in this, and in the consumption, not in the specific power. The specific power is useless.

Why did you tell that the lack of improvements was in the period 1928-1937? AS5 ran in 1929. AS6 ran between 1931 and 1934. The A.30 (why anemic?) was a AS5 evolution. It was the CR30 and CR32 engine. Both excellent aircraft. And the final (unfortunately!) A.30 evolution was the A.33.

I said that cause the AS.5 and AS.6 are exclusively race engines, whose only spin-off was an underpowered engine, that has not been further developed (also the Jumo 210 was underpowered, but it was evolved). In the same years were set the projects for the Allison V-1710, DB 600 and RR Merlin. You don't see a lack of planning in Italian inlines in those years?
There are no doubts that the A.74 was an overall better engine than the A.30, and, again, the power/displacement ratio has little to do with it.

Excuse me. I'm tired of rumors...

I am very sorry that you're tired, but frankly I did not understand what you're complaining to me.

 

[Dogwalker]

Did I mention that the same FIAT had a better engine (with a good compressor) to use as a base for further developments: the A.33. But they preferred to satisfy hierarchies and continue safe production. The hierarchies were wrong? It was better indulge them, to defend private interests of the FIAT!

Excuse me, Sibboh, but, speaking of "unsupported rumors", if the FIAT was the manufacturer of both the A.30 (projected evolution A.33) and the A.74 (projected evolution, A.76), Why choose radials means "defending private interests of the FIAT"? Indeed, in the area of in-line engines the only competitor for the FIAT was the Isotta Fraschini, in the area of radial, there were also Alfa Romeo and Piaggio, the competition was harder.

The FIAT was not a monopoly in Italy?!?

No, it was'nt ,even if the question is written with many marks. There was competition for both the engine and in the aircrafts. Fiat produced the G.50, and wasn't able to impose a good aircraft as the CR.25 over the terrible Ba.88. Mistakes were certainly made in the choice of Italian aircrafts first than the beginning of the war, as in the aircrafts of other nations for that matter (it's hard to say that the Defiant or the Fulmar had been the best choices available, and even the USA, in 1940, had in service some not really very successful aircraft), but is not that all arise from the fact that FIAT was protected politically. It was, but that's not an explanation for all.

And the A.74 wasn't the best best engine available. And infact nobody tell anything about Asso XI and its derivative, the L.121.

I know the Asso XI, and I agree it would be a better choice, in general, than the A .74, but I was talking about radials, since radials were the choice of the Air Force.

In fact, in 1940-41 the Reggiane who had never invented engines, but only licensed products, it began a research on new engines. Among the various projects (of which it was made only the Re.103 RC50 I) there was a modernization of the Asso L.121. But then, although the project was complete, it was not realized.

Remember that Reggiane was part of the Caproni group, the owner of IF. There is nothing strange for their experimental section to try to improve IF products. It's the kind of the relationship that exists between the HRC and Honda. Visually, even the Re.103 seems an inverted V IF W18 equipped with a DB-like compressor.

for me, it was not so difficult to reach the 31.1 CV/L necessary to the 1000 cv continuous power output at altitude

Agree on that. In theory, it would be sufficient to equip an Asso XI RC40 with a compressor able to produce, at 4000m, the 841mm hg the Asso XI RC15 had at 1500m (normal operating pressure, not overboost), and it will produce more than 1000hp at 2400rpm at 4000m only for the lower counterpressure at the exhaust.
But IF developed more advanced compressors for the Delta and the Zeta, not for the Asso.
Cause, after the production licence of the DB601 was aquired (by the Alfa Romeo in this case, not the Fiat), for the Asso XI / L121 there was no more possibilities on the market (remember that, even at the same power output level, the Regia Aeronautica preferred inverted V engines for fighters, Infact they forced FIAT to invert the V of the A.38 ) the developement would have had to be made before. Also an IF L.122 that would produce, say, 1200 hp, in 1941, would have been useless with the DB601 already available.

 

[sibboh]

I'm sorry. I misunderstood your speech. I interpreted as a simple critics.
I like to discuss about engines.

 

[Dogwalker]

Happy to hear that, and thanks for the interesting tables.

 

[rinkol]

It seems that there might have been too many companies chasing the aircraft engine business in Italy. There also seems to have been some unnecessary duplication, for example, Piaggio and IF both licenced the Gnome Rhone 14K, though IF does not seem to have persisted in the development of this engine.

 

[Dogwalker]

In the '30s, in Italy, only Fiat and Isotta Fraschini had the capacity to industrially produce the big V12s (and more), which require large-size castings (Alfa Romeo produced smaller, V8, engines). Probably was not a good thing that FIAT has given up on this market, leaving the Isotta Fraschini with only the internal competition between its two lines of in-line products, air-cooled (Gamma, Delta, Zeta ...) and liquid-cooled (Asso 500, 750, 1000, XI ...).
When the Air Force began to ask radials, Alfa Romeo (the smaller of the "bigs"), that from the '20s produced the Jupiter on licence, was almost monopolist on this market. It was natural for others to try to get in, given also that the radials, especially as long they were single row, required casting and forging of smaller size than inlines, and therefore much smaller investments (Other than Alfa Romeo, Fiat, IF and Piaggio, also OM and OMIR produced radial engines , on Fiat and Piaggio design).
However, it is difficult to say whether it was a defect. In the '30s the market for high-power radials was relatively new for Italian firms, and it was difficult to say which was the most promising design. So much that, in the end, they all attained fairly easy to produce a 1000 hp engine, but nor the Alfa Romeo products, (Bristol derived, also visually beutiful in their cleanliness), nor the FIAT products (P&W derived, much appreciated by mechanics for ease of operation) were able to go beyond this. The only ones to do it were those which, on paper, seemed to be more primitive, the Gnome et Rhone derived Piaggio engines.
With the benefit of hindsight, it was perhaps a mistake, when the P.XII reached the 1500 hp, do not focus only on the production and development of that line of radials, but, back then, it was hard to make that choice, partly because the Alfa Romeo 135 was homologated few weeks before the P.XII (so, it seemed ready, even operationally), and promised better performances, but then it was never really ready for operational use.

 

[sibboh]

There are a lot of things to talk about.
Perhaps it would be useful to open a new topic. What do you think?
For the moment I continue the discussion here.

the P.XIX was definitely service in September 1943, and, in the "experimental" section, are listed engines already widely tested, for which the Air Force had ordered the production of thousands of copies, with engines that could have been be set just on paper

Yes, there are different errors in the chart. But other data are interesting, like the P.XIX RC.50-2V that supplied, if this is correct, 1250 cv at takeoff, when the P.XIX RC.45 supplied only 1100 cv.
Probably the author had the opportunity to visit the Aeronautica historical archieves. But he had no good knowledge about engines.

I know, and personally I like the Zeta very much. Personally I believe that the most part of It's problems, as for that of the more powerful versions of the Delta, were more due to the installation on a particular aircraft (for such an engine, dimensioning and positioning of air intakes and exhausts required a more careful work than of the positioning of a NACA cowling, or a radiator, in conventional engines), that to the engine itself. But the fact remains. The Zeta still had several problems in autumn 1943. The P.XV didn't had the same problems, and was a world class engine in 1943, demonstrating that it was possible to do them, even in Italy (harder it was to prepare a mass production, the real problem in Italy was manufacturing, not of designing).

Yes, i agree. But i wanted to tell another thing. The italian errors were to discard any particular engines instead of developing them, keeping certain inefficient projects (i refer in particular to A.80), and engaging in challenging projects in a time of emergency, when it was more useful to make efficient and functional things. The italians new projects were a V16 (possible torsional vibrations with a so long and complex crankshaft), X24 Zeta and Sigma (complex solution and cooling problems in an inline aircooled engine), etc...
Also Allied and Germans had peculiar projects, but the most important war engines were traditional (V12, R14 and R18).
P.XV was good for bombers. But a fighter was projected at the end of 1942 (the interesting Piaggio P.32). Too late. This engine had the same P.XII dimensions. The diameter was 1410 mm. A big encumbrance! P.XI diameter was 1328 mm, P.XIX diameter 1274 mm, Fiat A.74 diameter 1195 mm. Obviously a high frontal surface was a serious aerodynamical obstacle. Particularly with a reduced power. Also the ratio between power and the front surface must be at least good.

I don't consider it, cause it means very little. We are not talking about a race in which there are displacement limits.
It's natural for the smaller displacement engines to have an higher specific output, but, on air, what count more is the hp output, then the hp/weight ratio, then the hp/dm2 (a lot less than the previous ones, since the drag of the engine is only part of that of the entire aircraft, and, for the inlines, the drag of the radiator is rarely taken into account). For example, if (simplifying) a Piaggio P.XII has the same power, the same weight and the same diameter of a Bristol Hercules, what does it matter if the first is a 53l engine that obtain the same power of the second (a 39l one) functioning at lower rpm? They are engines of the same class. The efficiency of an aircraft engine is measured in this, and in the consumption, not in the specific power. The specific power is useless.

RR Merlin had the lowest displacement, but was very powerful. Infact his ratio between the power and the displacement is the best. Yes, it didn't matter if there was a powerful engine. But bigger engine is heavier engine. So if i have a good ratio between the power and the displacement i can compensate for the weight and size. I didn't want to tell that italian engine industry needed the same cv/l ratio than Merlin or V-1710. I wanted to tell that there was the ability to build engines with a good cv/l ratio. Alfa was a good chance. It had a small diameter for its displacement (similar to P.XI diameter). And probably Alfa 136 was a project to overcome the problems, and with a new powerful supercharger. When i used efficienty i wanted to tell that the P.XII wasn't a good solution with his high displacement, high weight, high frontal surface and a low cv/l ratio. The power didn't compensate for the defects. At least if I think it as a fighter engine. The R-2800 diameter was 1341 mm. It had a good cv/l ratio (not the best but very good), therefore an high power with a middle frontal surface for a middle-big radial engine. I'm not a technician. But i need to understand. And i regard the cv/l ratio a good way to understand. But obviously not only this. Only a way.
Sometimes i dream a derivative of the Alfa 135 with a shorter stroke (150mm instead of 165 mm) and therefore a smaller displacement (45.2 L instead of 49.722). For me it could be able to provide continuous 1400 cv or a bit more only with the same Alfa 128 supercharger. This supercharger provided (in 1937) 1,40 ata (circa 1030 mmHg, 40,5 inHg, + 5.2 psi) at takeoff and 1,26 ata (circa 927 mmHg, 36.5 inHg, +3.2 psi) at altitude in normal continuous conditions. But this is fancy.

 

[sibboh]

I said that cause the AS.5 and AS.6 are exclusively race engines, whose only spin-off was an underpowered engine, that has not been further developed (also the Jumo 210 was underpowered, but it was evolved). In the same years were set the projects for the Allison V-1710, DB 600 and RR Merlin. You don't see a lack of planning in Italian inlines in those years?
There are no doubts that the A.74 was an overall better engine than the A.30, and, again, the power/displacement ratio has little to do with it.

Excuse me, Sibboh, but, speaking of "unsupported rumors", if the FIAT was the manufacturer of both the A.30 (projected evolution A.33) and the A.74 (projected evolution, A.76), Why choose radials means "defending private interests of the FIAT"? Indeed, in the area of in-line engines the only competitor for the FIAT was the Isotta Fraschini, in the area of radial, there were also Alfa Romeo and Piaggio, the competition was harder.

The Fiat A.30 prototype ran for the first time in 1930 (or 1929 ?).
The designer was Tranquillo Zerbi (born in 1891 and died in 1939). He designed the inline engines A.20, A.22, A.24, A.25, A.26, AS.2, AS.3, AS.5, A.30, AS.6, the small inline aircooled A.60 and the radials A.50, A.53, A.55, A.70, A.74 and A.80).
Then there were two production versions: A.30RA (1930) and A.30RA bis (1933). Both unsupercharged. They used 94 octane fuel. I'm doubtful about it. In: Oscar Marchi (author), 1980, "Aeronautica militare. Museo storico. Catalogo MOTORI", Pàtron Editore (Publisher) at pages 78 and 88, when the author talks about A.30 bis and A.33 respectively, he says 94 NO (Numero Ottani - Octane Number). But i think that at the beginning of 1930s there wasn't that grade... is it possible that it's a mistake and the real grade was 84? I do not know very much about fuels.
In 1933 there was a supercharged prototype: A.30RC (R=Riduttore=ReductionGear, C=Compressore=Supercharger).
Fiat first experimented the use of the supercharger in an aircraft engine in 1923. The small 12V (only 9.782 L) FIAT A.19 had two Roots superchargers. Infact it had a high specific power for the time (continuous 29.6 cv/l; max 35.8 cv/l. Both at 3500 m).
In the same year, 1933, after the A.30RC the designers Fessia and Giacosa (the first engineer projected: A.74 and A.80 together with Zerbi, and then A.76, A.82, AS.8, A.38, etc...) studied Roll-Royce and Hispano-Suiza engine's solutions (Kestrel IIS, IIIS or most likely the recent Kestrel V and the Hispano-Suiza 12 Xbrs, i suppose).
Marchi wrote (page 88): "Il nuovo motore è dotato di un poderoso originale e complicato carburatore con regolazione automatica in funzione della temperatura e della pressione variabili con la quota. ... Ne riuscì un motore eccellente; certamente uno dei migliori e tecnicamente avanzati tra i motori realizzati dalla Fiat e che fu l'ultimo 12V. L'A.33 era confrontabile per caratteristiche, prestazioni ed affidabilità con il Kestrel della R-R."
"The new engine is equipped with a powerful and complicated original carburetor with automatic adjustment in function of the temperature and pressure variables with the altitude. ... It succeeded an excellent engine; certainly one of the best and technically advanced of the engines made by Fiat and that was the last 12V. The A .33 was comparable in features, performance and reliability with the Kestrel of R-R.". Likely it had a good supercharger. Better than the A.74 supercharger (only 790 mmHg, 31.2 inHg, +0.6 psi, 1,074 ata at continuous output!!!!) or the A.80 supercharger (only 740 mmHg, 29.1 inHg, -0.4 psi, 1,006 ata at continuous output!!!!!!!!). Why FIAT did not improve at least the superchargers of its radial engines?
Isotta Fraschini Asso XI was born in 1934. It had a better supercharger than A.74 and A.80 (And it took a little ... ). Between 1934 and 1938 its boost grew.
A.30RA was good but unsupercharged (even Kestrel had unsupercharged versions. The most important were: IB produced in the period 1929-34, and X produced in the period 1934-36). A.30RC (1933) and A.33 (1935) were supercharged. Also IF Asso XI (1934-38) was supercharged. And they weren't racing engines.
The last was bigger than Merlin and V-1710, but in the same displacement range than DB600/601, even if a little bit smaller.
The engineer that projected the Asso XI was Cattaneo. He also designed: IF Asso 500, 750, 1000, Asso Caccia, Alfa 126 and Alfa 135.

 

[sibboh]

No, it was'nt ,even if the question is written with many marks. There was competition for both the engine and in the aircrafts. Fiat produced the G.50, and wasn't able to impose a good aircraft as the CR.25 over the terrible Ba.88. Mistakes were certainly made in the choice of Italian aircrafts first than the beginning of the war, as in the aircrafts of other nations for that matter (it's hard to say that the Defiant or the Fulmar had been the best choices available, and even the USA, in 1940, had in service some not really very successful aircraft), but is not that all arise from the fact that FIAT was protected politically. It was, but that's not an explanation for all.

Fiat produced 778 G.50 (one of the most produced italian fighter), circa 1800 CR.42 (the most produced italian fighter). FIAT was the most important italian industry.
Breda produced only 149 Ba.88.
And the Caproni group? Ca 309-314 apart, even if this industry presented a great number of projects, only a small number were put into production. I remember several airplanes and projects:
Caproni Ca.165 (better than CR.42), Caproni Vizzola F.5 (better than G.50), Reggiane 2000 (better than G.50), Ca.331 (very good), Reggiane P.32 II (stopped at the beginning of the flight development because the Piaggio P.32, the progenitor but virtually another plane, had many problems), the Ca.153-156 and Ca.155II, the Ca.350 (modern development of Ca.335), Caproni Bergamo Ostro, etc...
At the beginning of 1940 there were rumors of a possible installation of the L.121 on one of the prototypes Macchi C.201, later called project Macchi C.204. On the other hand I know that the engineer Castoldi preferred an in-line engine when he designed the Macchi C.200. As well as Fabrizi for his F.5.
Than i could remeber some IF Asso XI-L.121 or Asso L.180 powered aircraft or project (Isotta Fraschini was part of Caproni group): the initial draft of the Ba.201 (and its realized mock-up), the Stefanutti project SS.4, the Ca.165 and Ca.175, the Jona heavy fighter-bomber family J.10, J.11C, J.12, the IMAM Ro.53 etc...

I know the Asso XI, and I agree it would be a better choice, in general, than the A .74, but I was talking about radials, since radials were the choice of the Air Force.

And infact it was a bad choice. One of many bad choices!

Remember that Reggiane was part of the Caproni group, the owner of IF. There is nothing strange for their experimental section to try to improve IF products. It's the kind of the relationship that exists between the HRC and Honda. Visually, even the Re.103 seems an inverted V IF W18 equipped with a DB-like compressor.

Yes, but if Asso L.121 (and projected L.122) didn't run, as some rumors tell us, this choise was very strange...

Agree on that. In theory, it would be sufficient to equip an Asso XI RC40 with a compressor able to produce, at 4000m, the 841mm hg the Asso XI RC15 had at 1500m (normal operating pressure, not overboost), and it will produce more than 1000hp at 2400rpm at 4000m only for the lower counterpressure at the exhaust.
But IF developed more advanced compressors for the Delta and the Zeta, not for the Asso.
Cause, after the production licence of the DB601 was aquired (by the Alfa Romeo in this case, not the Fiat), for the Asso XI / L121 there was no more possibilities on the market (remember that, even at the same power output level, the Regia Aeronautica preferred inverted V engines for fighters, Infact they forced FIAT to invert the V of the A.38 ) the developement would have had to be made before. Also an IF L.122 that would produce, say, 1200 hp, in 1941, would have been useless with the DB601 already available.

I'm not so optimistic about boost necessary to reach normal continuous 1000 cv at altitude. I think almost 900 mmHg (1,22 ata). But DB601Aa needed 1,23 ata at the same rpm at 4500 m (the stroke was the same). The other DB601 versions use a lower boost and rpm (only 1,15 ata and 2200 rpm DB601A-B, 2300 rpm DB601N, E-G).
The Delta RC35 I (1938) supercharger gave only 1,16 ata (circa 850 mmHg) at takeoff and 1,05 ata (circa 770 mmHg) normal continuous at 3500 m.
The Asso XI RC 40 (and not the powerful L.121) already in 1935 provided a boost of 900 mmHg (1,22 ata) at takeoff and 822 mmHg (circa 1,12 ata) normal continuous at 4000 m.
The hierarchies began to realize that it was better to focus on in-line engines as early as 1938. In 1939 they bargained with Daimler Benz to the production license. The Alfa Romeo began to prepare it in 1940. The production began only in 1942 (in 1941 only the assembly of pieces of German production).
Fiat began the study of a new inline engine only in 1939-1940, when the Alfa Romeo gained the DB601Aa license production. And the Fiat engineer used AS.8 as the basis simply because they have it.
When you do things at the last minute (in a hurry), you always hurt ... (my opinion)
The project L.122 Asso was ready in 1938. The engine already existed, the L.121. In 1939, the Macchi C.201 prototype was ready. If the prototype engine was ready in 1939, could begin production in 1940. If in 1940, production began in 1941. In any case, before the production of the DB601. Meanwhile, you could power the fighter with the least powerful L.121. Subsequently the necessary changes for the new engine L.122 would be very few. There was the time required. If there was the will.
About inverted V12 engines, IF had an engine of this time before DB601Aa ran for the first time: the Delta (first ran in 1936-37). So they had the knowledge, if necessary.

I don't know if I've answered all matters of Dogwalker. And probably there will be mistakes (I hope not). But it is inevitable ...
However now the discussion is really wide. But I love it.

 

[sibboh]

I hate emoticons!!!!! Every ****ing emoticon is an 8 !!!!!!!!! Sorry

 

[sibboh]

A mistake, sorry:
About inverted V12 engines, IF (Isotta Fraschini) had an engine of this type before DB601Aa ran for the first time: the Delta (first ran in 1936-37). So they had the knowledge, if necessary.

 

[Shortround6]

Put a space between the 8 and the ) = 8 )

I think we all have been caught by that one 8)

 

[Dogwalker]

P.XV was good for bombers. But a fighter was projected at the end of 1942 (the interesting Piaggio P.32). Too late. This engine had the same P.XII dimensions. The diameter was 1410 mm. A big encumbrance! P.XI diameter was 1328 mm, P.XIX diameter 1274 mm, Fiat A.74 diameter 1195 mm. Obviously a high frontal surface was a serious aerodynamical obstacle. Particularly with a reduced power. Also the ratio between power and the front surface must be at least good.

Not only the P.XV would have been good for a fighter, but even It's predecessor, the P:XII would have.
1410mm. vs 1328mm means that the P.XII had 50% more power than the P.XI with less than 13% more frontal surface. A real gain to me. Infact, the same chart you posted, list the P.XII RC.35 as having the best hp/dm2 ratio of all the engines "in service" (with the exception of an "A.80 RC.42", really the A.82 RC.42, that, in reality, had even more problems than the A.80 from which was derived), so more than only "good". And the front surface does not tell the whole story. The P.XII (as the P.XV, that was buried in the fuselage of the P.119) was a "cold" engine, on which were used the very enclosed, aerodinamically efficient, cowlings we see on the Cant Z.1018 and Caproni Ca.169. In the end, the aerodynamic hindrance of mere 4cm more radius, on an aircraft as the Re. 2000, would have been negligible. But the high ranks of the Air Force turned up their noses even for the use of P.XI on a fighter. For them, even the P.XI was "a bomber's engine", without taking into account that both the Macchi C.200 that the Fiat G.50 had wider fuselages of their Fiat A.74 engine, so the advantage of the small engine was void.

The R-2800 diameter was 1341 mm

And how much the fuselage of a Tunderbolt or an Hellcat was wider than the engine? Those aircrafts could easily accommodate a wider engine than the R-2800. Only the Corsair took real advantage of the limited frontal surface of the R-2800.

RR Merlin had the lowest displacement, but was very powerful. Infact his ratio between the power and the displacement is the best. Yes, it didn't matter if there was a powerful engine. But bigger engine is heavier engine.

Really?
Remaining to the example of the P.XII, this 53l - 850kg dry-weight engine turned out to be lighter than the Bristol Hercules (39l - 875kg), BMW 801C (42l - 1012kg), and Alfa Romeo 135 RC.32 (49l - 970kg).
The power to weight ratio is important, I told that, but, since we can look at the actual weights, we do not need to say that the-engine-with-the-best-specific-power-is-better-because-the-lower-capacity-could-mean-a-lower-weight. Is the power to weight ratio to be important, non the could-be one, and the specific power tell us only the could-be one.
The Alfa Romeo 135 would certainly have been a better engine, for a fighter, than the Piaggio P.XII, if it had worked. Unfortunately it never worked decently. His successor Alfa Romeo 136 maybe had the problems solved, but how many Alfa Romeo 136 were built? In September 1943, the successor to the P.XII, the PXV, had flown on several aircrafts, had been ordered for mass production, and on the the bench was tried the even more powerful P.XXII.

Marchi wrote (page 88): "Il nuovo motore è dotato di un poderoso originale e complicato carburatore con regolazione automatica in funzione della temperatura e della pressione variabili con la quota. ... Ne riuscì un motore eccellente; certamente uno dei migliori e tecnicamente avanzati tra i motori realizzati dalla Fiat e che fu l'ultimo 12V. L'A.33 era confrontabile per caratteristiche, prestazioni ed affidabilità con il Kestrel della R-R."

Only that the Kestrel run for the first time in 1927, and the Fiat A.33 run in 1935. In 1935 RR was preparing the Merlin and the Griffon. I'm still seeing a lack in planning on italians inlines in the years from 1929 to 1937 more than after.

Isotta Fraschini Asso XI was born in 1934. It had a better supercharger than A.74 and A.80 (And it took a little ... ).

Sure? The A.74 supercharger was still able to give 890mm hg at 3000m. The Asso XI RC.40 supercharger can give more than 822mm hg only up to 2000m. Is not than the supercharger isn't able to give the boost, is that the engine is designed to function more or less at atmosferic pressure, and can be supercharged only for few minutes.

Fiat produced 778 G.50 (one of the most produced italian fighter) ... Breda produced only 149 Ba.88.

And so?
Apart that they were 148 twin engined (vs 1), two seat (vs 1) , 4650kg dry heavy (vs 1975kg), 4 MGs armed (vs 2) aircrafts, so those 148 alone count for more than 296 as depleted resources; they were "only" 148 only cause the Regia stopped the production as they saw that the aircraft was completely useless (that can't be said for the G.50). More than 148 aircraft were planned. So, choosing the Ba.88 over the Cr.25 not only led to produce 148 completely useless aircraft, but to not produce several hundreds of useful ones.
So, the questions is:
Wanted the FIAT, the CR.25 to be chosen instead the Ba.88? Yes.
Was the Cr.25 a better aircraft than the Ba.88? Yes.
Was the FIAT able to impose the Cr.25 over the Ba.88? No.
So was the FIAT a monopolist? No, it was in competition with other firm, both as engines than aircrafts producer.
So was the Regia Aeronautica at the service of Fiat? No. The Regia made several errors in choosing his planned line of aircraft, sometimes penalizing even the FIAT.

Why "Ca 309-314 apart"? Where they not choosen by the Regia? Were not built hundreds of them?
And the Cr.25 could have been a better aircraft in every role they performed (transport, reconnaissance, light bombing...), as had to realize the hard way the 173ª Squadriglia Ricognizione Strategica Terrestre. Here also, the decisions of the Regia penalized the FIAT preferring a worse aircraft. The FIAT was politically protected? Yes, it was, as were Breda, Macchi, Piaggio, and even the Caproni group (even if the Count Caproni had a reputation for being anti-fascist, to a nobleman was allowed).
In the choosing of the G.50, must be taken into account that the fighters of the "0 series" were considered interim fighters by the same commission that choose them, waiting for the paperwork for the licensed production of DB601 to be completed. The FIAT was by far the firm whit the bigger manufacturing capacity, so, choosing a FIAT product means to have quikly what was ordered (infact the first G.50s were ready to be used in Spain). Choosing another product, means to decide where to produce it (infact, for example, the biggest manufacturer of C.202 was the Breda plant, not the Macchi) and have it later.
The same logic we see in the choice of C.205V. It was the worst performer at high altitude of the "5 series" fighters, not a small defect, as the task of the fighters was now almost only the interception of bombers, but was put in production as, being pretty much just a re-engined C.201, was immediatly available.
The fact that the FIAT was politically protected is true, but it's not an explanation good for all.

At the beginning of 1940 there were rumors of a possible installation of the L.121 on one of the prototypes Macchi C.201

Could be, but, since the Alfa Romeo acquired the production licence of the DB601 at the end of 1939, the choice of using it was pretty obvious.

Yes, but if Asso L.121 (and projected L.122) didn't run...

The L.121 surely run. It was the engine of the Ca.165 and of the Caproni-Campini N.1 for example. It was hologated for aircraft use, only that the Regia didn' want it on fighters.

IF had an engine of this time before DB601Aa ran for the first time: the Delta (first ran in 1936-37). So they had the knowledge, if necessary.

Surely they had the knowledge, but they didn't apply it on their most powerful products, as, at the time the DB601 licence was acquired, the Delta didn't produced more than 770hp. Surely not bad for a 27l, two valves, air cooled engine, but still only 770 hp.
Personally I LOVE the IF air cooled inlines. This picture ( http://upload.wikimedia.org/wikipedia/commons/c/c4/F11_Museum_-_Stockholm_Skavsta_-_P1300085.JPG ) touches me, for how well that engine was done. And I think that the real mistake of IF was not having developed during the '30s a liquid-cooled, rebored, four valves version of the Delta. This would have really made licence of the DB601 useless, but, since that engine was not there, while the DB601 was... it was much better than the production license of the DB601 has been purchased, and that the real engine has been used.

 

[sibboh]

A) Only that the Kestrel run for the first time in 1927, and the Fiat A.33 run in 1935. In 1935 RR was preparing the Merlin and the Griffon. I'm still seeing a lack in planning on italians inlines in the years from 1929 to 1937 more than after.

B) Sure? The A.74 supercharger was still able to give 890mm hg at 3000m. The Asso XI RC.40 supercharger can give more than 822mm hg only up to 2000m. Is not than the supercharger isn't able to give the boost, is that the engine is designed to function more or less at atmosferic pressure, and can be supercharged only for few minutes.

A) Yes, the first supercharged Kestrel ran in 1928. There were the IMS, IIMS, IIIMS family (1) and the IS, IIS and IIIS family (2).
The normal continuous power output:
1) 500 hp (507 cv), 2250 rpm, +1.375 psi (831 mmHg) at 3000 ft (914 m)
2) 480 hp (487 cv), 2250 rpm, -0.5 (734 mmHg) at 11500 ft (3505 m)

Takeoff power output was (limit 1 minute):
Kestrel IIMS (1928-35): 558 hp (566 cv), 2500 rpm, +1.5 psi (838 mmHg)
Kestrel IIS (1928-38): 480 hp (487 cv), 2250 rpm, +1.75 psi (851 mmHg)
Kestrel IIIMS.6 (1935): 650 hp (659 cv), 2700 rpm, +1.5 psi
Kestrel IIIS (1930-38): 580 hp (588 cv), 2700 rpm, +1.75 psi

Then we have to await the 1933 when Kestrel V ran for the first time.
But you forget the A.30RC (this had supercharger). It ran for the first time in the 1933. And we don't know its performances. Unfortunately it was only a prototype.

A.30RA bis provided:
600 cv at 0 meters, 2600 rpm, no limits
700 cv takeoff, 2750 rpm - 5 minutes limit
550 cv at 2750 meters, 2750 rpm - no limits
It was competitive. And hierarchies were happy to have a good engine. And very good aircraft (CR.30 and CR.32). Be content was surely a mistake.
But the fact remains that the technicians had the appropriate knowledge. Products manufactured also depend on the client (the government). And as long as no one will study the documents of the companies (as was done in the UK and USA), we will not know more.

B) Yes! I'm sure. Do you see the small circles in the Asso XI RC40 engine chart? The normal continuous power output is 822 mmHg at 2250 rpm at 4000 m.
"RC40" means engine with Reduction gear and Compressore/supercharger at 4000m. The other circles are other power conditions, with other boosts.
http://www.ww2aircraft.net/forum/attachments/engines/230775d1365879959-terminology-engine-data-crve.jpg
But really do you think that IF Asso XI was practically unsupercharged?
A.74RC38 used 890 mmHg only in takeoff and emergency conditions (per pochi minuti/for a few minutes).
Asso XI RC40 used 900 mmHg at takeoff, and 890 mmHg in what is most likely the same emergency condition (and the power is similar). The small circle at the top of the engine chart. The engines ran for the first time in the same 1935. But here the frontal surface is very significant. But Asso XI RC40 had other two versions: XI RC40 "spinto" (1936) and L.121. I like to see Asso L.121 data. The boost was surely higher.
Infact Asso "spinto" had a 920 mmHg takeoff boost (i don't know the power output) and 850 mmHg at 2300 rpm at 4000 m (i don't know the power output nor the condition. But i think lower than normal continuous because the normal rpm were 2350).

 

[sibboh]

I forget 8) 8 ) 8) 8 ) 8) 8 ) ...

 

[Dogwalker]

But you forget the A.30RC (this had supercharger). It ran for the first time in the 1933. And we don't know its performances. Unfortunately it was only a prototype.

Another not developed prototype. One of many. Talking about "lack of planning".

And hierarchies were happy to have a good engine.

So they were happy to have, as the epitome of Fiat inline products, an engine competitive whit one for which the RR was already preparing the two next stage of evolution. I'm still seeing a lack in planning on italians inlines in the years from 1929 to 1937 more than after.

But the fact remains that the technicians had the appropriate knowledge.

Who doubt? I wrote "lack of planning", not "lack of knowledge". But not having planned the developements in the years 1929-1937, led to the lack of knowledge after, when the A.38 had to be built, since is difficult to double the power of your main inline engine without intermediate steps.

Do you see the small circles in the Asso XI RC40 engine chart?

Yes. Did you read the manual? Asso XI RC.40's supercharger was able to give more than 822 mm hg (overboost) only up to 2000m, while the A.74 supercharger was able to give 890mm hg at least up to 3000m.

But really do you think that IF Asso XI was practically unsupercharged?

The A.74 is designed to function more or less at atmosferic pressure, and can be supercharged only for few minutes. We were talking about an an alleged inferiority of the supercharger of the A.74, remember? But: "Is not than the supercharger isn't able to give the boost, is that the engine is designed to function more or less at atmosferic pressure, and can be supercharged only for few minutes", but if the engine demanded more pressure, the compressor of the A.74 was perfectly capable of supercharge it.

A.74RC38 used 890 mmHg only in takeoff and emergency conditions (per pochi minuti/for a few minutes).

Cause is designed to function more or less at atmosferic pressure, and can be supercharged only for few minutes.

 

[sibboh]

Another not developed prototype. One of many. Talking about "lack of planning".

Yes, there was a lack of planning in all italian union history. I told that there were problems, during 1930s, due to political incompetence, to clientelism and to contrasts between different potentates (political, industrial...), that were part and cause of the "lack of planning".

So they were happy to have, as the epitome of Fiat inline products, an engine competitive whit one for which the RR was already preparing the two next stage of evolution. I'm still seeing a lack in planning on italians inlines in the years from 1929 to 1937 more than after.

Infact i didn't tell "lack of plannings" when i first spoke about italian problems (4-28-2013 02:28), but i told: "There was a lack of improvements during the 1937-1940 period.". Improvements. During the 1929 to 1937 period at least there were a bit of improvements. Not plannings. Plannings is a political problem. And on this, I think, we fully agree.

Who doubt? I wrote "lack of planning", not "lack of knowledge". But not having planned the developements in the years 1929-1937, led to the lack of knowledge after, when the A.38 had to be built, since is difficult to double the power of your main inline engine without intermediate steps.

In this we are not quite agree. Certainly the lack of planning has created problems. You believe that there has been no development between 1929 and 1937. So that the characteristics have remained steadfast and therefore the same. I do not see this. I see an improvement of between 1929 and 1937. (I've created a table with data to prove it. Data are put into chronological order. Features checked and I entered a small bibliography.) Instead I see the lack of improvement of engine performance at least for the period 1937-1940, when really the characteristics were the same (the example of A.74 for me may suffice: 1935-1942!). Certainly not doing proper research in previous years and had not improved by degrees existing engines has created many problems. And that's why I said from the beginning. But I do not think there were large gaps of knowledge when the A.38 was designed and built. This is the difference between what I think and what you think.
Instead, I believe that the problems were not solved because they tried to do things in a hurry and at the last moment! As I have said many times, and I'm tired of repeating myself, the things done in a hurry are always badly made.

Yes. Did you read the manual? Asso XI RC.40's supercharger was able to give more than 822 mm hg (overboost) only up to 2000m, while the A.74 supercharger was able to give 890mm hg at least up to 3000m.

Yes, i read manual. So you have to give me the page, because i don't see it. I see only a problem about takeoff in plateaus up to 2000 m. But takeoff, not overboost at altitude. The power chart tell me other.

The A.74 is designed to function more or less at atmosferic pressure, and can be supercharged only for few minutes. We were talking about an an alleged inferiority of the supercharger of the A.74, remember? But: "Is not than the supercharger isn't able to give the boost, is that the engine is designed to function more or less at atmosferic pressure, and can be supercharged only for few minutes", but if the engine demanded more pressure, the compressor of the A.74 was perfectly capable of supercharge it.

Atmospheric pressure is 760 mmHg. 790 mmHg or 822 mmHg aren't atmospheric pressure. DB 601 and DB 605 give a normal continuous power output at 1,15 ata, 846 mmHg: is it more or less at atmospheric pressure? Kestrel IS/IIS/IIIS only 734 mmHg, really less than atmospheric pressure.
What is the boundary to overcome the "more or less at atmospheric pressure"?

Cause is designed to function more or less at atmosferic pressure, and can be supercharged only for few minutes.

Grazie, non l'avevo capito. Scusa il sarcasmo.
If you see the engine power charts about different engines from all the countries, all had time limitations in takeoff and emergency.

 

[Dogwalker]

Infact i didn't tell "lack of plannings" when i first spoke about italian problems (4-28-2013 02:28), but i told: "There was a lack of improvements during the 1937-1940 period.". Improvements. During the 1929 to 1937 period at least there were a bit of improvements.

During the 1937-1940 period the power output of the Italian radials grew up of more than 50%, and were set the path for further developements.
Italian inlines produced more than 1000hp already in the '20s, but the path, from 1929 to 1937, was to continue to refine a 600hp engine without plans to go beyond it. Yes, i see a lack of improvements too.

Instead, I believe that the problems were not solved because they tried to do things in a hurry and at the last moment!

They had to do things in a hurry, at the last moment, cause they didn't do it before, while Allison, DB and RR were doing it. And the developement process of their main products (V-1710, DB600 and Merlin) were set from the late '20s to the early '30s.

Yes, i read manual. So you have to give me the page, because i don't see it. I see only a problem about takeoff in plateaus up to 2000 m. But takeoff, not overboost at altitude. The power chart tell me other.

On that page is clearly stated that the lever that manually open the intake valve of the supercharger, over 2000m is useless, since the automatic pressure control had already opened the valve more than the lever can do. If you can find other overboost commands in the manual, you have to tell me were they are. The only one listed, isn't able to give an overboost over 2000m.

What is the boundary to overcome the "more or less at atmospheric pressure"?

Are you that complained of the low working pressure of the A .74, blaming the supercharger, not me. I said that the supercharger was able to give more pressure, if required, and the manual shows it, but the engine isn't designed to require it.

If you see the engine power charts about different engines from all the countries, all had time limitations in takeoff and emergency.

Thank you very much, these are really great news. So the supercharger was able to give an overboost to the A.74, if required, or not? So, if the normal operating pressure was lover, is the fault of the supercharger, or is due to the features of the engine?

 

[Shortround6]

It is very hard to compare superchargers in this way. Superchargers can be measured in airflow (pounds of air per minute), Pressure ratio ( how much they compress the incoming air) and efficiency (what percentage of the power used to drive the supercharger is actually compressing the air).

When looking at engine charts you are looking at a complete engine system that has to take into account the strength of the engine (blowing cylinders off is not a good thing), the fuel used (only so much boost can be used with certain fuels) AND the desired characteristics of the engine in question.

as an example the British Mercury radial could make 830hp for take off and 890hp at 1800 meters using a 7.0:1 gear drive on the supercharger (using about 914mm) , great for a flying boat or seaplane. Change the gear ratio to 9.4:1 and high level power went to 840hp at 4250 meters but take-off fell to 725hp. (using just over 1000mm) Same supercharger intake, impeller and housing/diffuser. Much better for a fighter or light bomber.

At 4250meters the Mercury supercharger was compressing the air 2.27 times and lets face it, the Mercury supercharger wasn't exactly the latest and greatest.

Just about anybody could design a supercharger with a pressure ratio of over 2 to 1 in the 30s and by the late 30s 2.3-2.8 was fairly common. The two big problems where getting the engine to stand up to it and getting fuel that allowed you to use a boost pressure of over 4-6lbs, 38-42 absolute or the metric equivalent.

Italian radial engines were rather light for their size ( in some cases very light) which leads to suspicions of a lack of structural strength to tolerate higher RPM or over boosting.

Lack of planning in 1939-34 (or later) is a bit understandable, the fuel situation changed dramatically. France was another country that got caught with engines that were fine with 80 octane fuel, OK with 87 octane but near hopeless with 100 octane or higher. The basic engines were not strong enough to stand up to higher boost pressures with out either major redesign or starting over.

 

[sibboh]

During the 1937-1940 period the power output of the Italian radials grew up of more than 50%, and were set the path for further developements.
Italian inlines produced more than 1000hp already in the '20s, but the path, from 1929 to 1937, was to continue to refine a 600hp engine without plans to go beyond it. Yes, i see a lack of improvements too.

On that page is clearly stated that the lever that manually open the intake valve of the supercharger, over 2000m is useless, since the automatic pressure control had already opened the valve more than the lever can do. If you can find other overboost commands in the manual, you have to tell me were they are. The only one listed, isn't able to give an overboost over 2000m.

1) Example please.
2) Number of the page please.