davebender
1st Lieutenant
If the Macchi C202 has a DB601E engine there's no reason not to fire a cannon through the hollow prop shaft.
Italian copies of the DB 601
- Thread starter Sagittario64
- Start date
Ad: This forum contains affiliate links to products on Amazon and eBay. More information in Terms and rules
al49
Tech Sergeant
Hi, as far as I know Macchi C 202 only had the two 12.7 mg under the upper part of the cowling, firing through the propeller arc plus, on some machines, two 7.7 mg in the wings. No cannon firing through the spinner; I don't know exactly why, I will investigate and eventually let you know.
Alberto[/QUOTE]
OK, I found something searching an other forum.
The mean reason why the 20 mm cannon was never installed seems to be that the architecture of the 202, based on the radial engined 200, was such that to install the cannon, like in the Bf 109F, would have required major structural modification and there was no time for that: a better plane was desperately needed as quick as possible.
The same happened with the Macchi C 205V Veltro, derived from the 202 but with a DB605 engine: no engine mounted cannon either.
But this was a so called "interim" solution because the real machine, developed by Macchi to suit the DB605, was the the Macchi C 205N Orione which was armed with three MG 151 20 mm cannons and two 12.7 mm mgs. Only two prototypes made.
The final evolution was the Macchi C 207, designed to install the DB603 engine and sporting four wing mounted 20 mm cannons firing outside the propeller arc. A prototipe was started but the armistice stopped everything.
Just for your information here following are profile and plan of the latter.
Cheers
Alberto
Alberto[/QUOTE]
OK, I found something searching an other forum.
The mean reason why the 20 mm cannon was never installed seems to be that the architecture of the 202, based on the radial engined 200, was such that to install the cannon, like in the Bf 109F, would have required major structural modification and there was no time for that: a better plane was desperately needed as quick as possible.
The same happened with the Macchi C 205V Veltro, derived from the 202 but with a DB605 engine: no engine mounted cannon either.
But this was a so called "interim" solution because the real machine, developed by Macchi to suit the DB605, was the the Macchi C 205N Orione which was armed with three MG 151 20 mm cannons and two 12.7 mm mgs. Only two prototypes made.
The final evolution was the Macchi C 207, designed to install the DB603 engine and sporting four wing mounted 20 mm cannons firing outside the propeller arc. A prototipe was started but the armistice stopped everything.
Just for your information here following are profile and plan of the latter.
Cheers
Alberto
davebender
1st Lieutenant
Then why build the C.202 at all? License build the Me-109F plus the DB601E engine and Mg151/20 cannon. With minor improvements (Galland Hood, MW-50, new radio equipment etc.) the fighter aircraft would remain competitive to the end of the war. Me-109s were inexpensive to build so it's an ideal aircraft for mass production.
al49
Tech Sergeant
Yes, of course that could have been the easy way, but ...we should not forget two things: Italian industry these days was unable to start working in short time with German standards and, besides being allied, relations between Italy and Germany were not as good as they should have been. For instance, if I remember well, Italy had to struggle to get the first delivery of BF 109 when requested.
If you are interested in this subject and can understand French, there is a booklet written by the Italian expert Gregory Alegy that in less then 100 pages gives a very clear picture of Regia Aeronautica (and ANR) during WW2
Besides it was printed 11 years ago, the above book is may be still available on e-bay
Alberto
- Thread starter
- #25
Sagittario64
Airman 1st Class
Well it wasnt all bad. Germany accepted useless french bombers in return for giving italy somewhat useful dewoitine d.520s. and i also agree with you al49 on the cannon issue, now that youve brought some light upon it.
I was going to mention, but the document scan posted specifies it and the answer to the question is obvious.
Only the Aa motor was cleared for export, including licensed production. It is a detuned version of the 601A-1, but you have to remember the context is throttle altitudes. It has a smaller blower casing to reduce the throttle height, thus detuning it for the export market. As it turns out that also means slightly more output at lower altitude, but high altitude performance suffers. At 5000 metres you might have 150hp less in an Aa motor versus an A-1 motor and that is what is meant by the Italian measurement. You comparatively measure at the same altitudes, the A-1 has better altitude performance.
The Aa motor actually started mass production for the export market (extra rearmament dollars) during 1939 iirc (but was cleared for production just after the 601, much earlier, what I am assuming is that it was't stockpiled until 39 when sales to the Middle East, such as Turkey were planned...but as it turned out they got the Fw-190Aa instead and yes the nomenclature Aa means "export standard version"). As it turned out during the battle of britain there was a shortfall in Daimler engines, particularly as Heinkels used them (which caused the He-111H to be produced using Jumo engines). So all the surplus export 601Aa that were produced actually wound up in E-3 battle of britain emils. The hotrod N motor was preferred though, started production in 1940.
Anyways both Italian and Japanese fighters using Daimlers had the 601Aa copy.
Italians made it better than the Germans by the way. After they started making their own, Alfa demanded all their engines were indivdually hand finished and parts matched before assembly, they've a higher QC requirement but it's more expensive and time consuming.
Only the Aa motor was cleared for export, including licensed production. It is a detuned version of the 601A-1, but you have to remember the context is throttle altitudes. It has a smaller blower casing to reduce the throttle height, thus detuning it for the export market. As it turns out that also means slightly more output at lower altitude, but high altitude performance suffers. At 5000 metres you might have 150hp less in an Aa motor versus an A-1 motor and that is what is meant by the Italian measurement. You comparatively measure at the same altitudes, the A-1 has better altitude performance.
The Aa motor actually started mass production for the export market (extra rearmament dollars) during 1939 iirc (but was cleared for production just after the 601, much earlier, what I am assuming is that it was't stockpiled until 39 when sales to the Middle East, such as Turkey were planned...but as it turned out they got the Fw-190Aa instead and yes the nomenclature Aa means "export standard version"). As it turned out during the battle of britain there was a shortfall in Daimler engines, particularly as Heinkels used them (which caused the He-111H to be produced using Jumo engines). So all the surplus export 601Aa that were produced actually wound up in E-3 battle of britain emils. The hotrod N motor was preferred though, started production in 1940.
Anyways both Italian and Japanese fighters using Daimlers had the 601Aa copy.
Italians made it better than the Germans by the way. After they started making their own, Alfa demanded all their engines were indivdually hand finished and parts matched before assembly, they've a higher QC requirement but it's more expensive and time consuming.
Last edited:
Indeed the smaller blower in the Aa, which other than the blower is a 601A-1 engine, actually let the motor spin to its maximum emergency rating more easily and for longer.
The normal maximum rating of the 601A-1 is actually 1.3ata/2400rpm for 5min. During take off only (under 1000m) you could press it to 1.4ata at the same rpm but it rattled a lot and was under blower effiency height which is about 2000 metres.
The Aa blower lowers this to about 1500 metres maximum efficiency and helps it spin easier in thick air. Under 1000m the Aa will spin the 601 to 2500rpm/1.4ata instead of 2400rpm which is worth about 100hp.
But the lower throttle height is actually a reduction in performance. At 3800 metres the Aa puts out 1100PS military which is a little over 100hp more than the A-1, but at 4500m the A-1 puts out 1020PS military with good pressure and the Aa motor is dropping below 900hp and definitely out of breath. Maximum performance height for the airframe then rates at about 4200m for the Aa/Emil and about 5500m for the A-1/Emil, consider that typical frei-jäger in BoB is 7000m (because Spits lost climb rate at 6000).
Very loosely speaking comparing the A-1 to the Aa is very much like comparing a Merlin 45 to a 50. You do get higher maximums at low alt with a smaller blower that has a better efficiency down lower, but it really doesn't help you at fighter vs fighter combat heights, mostly for close ground support operations or escorts.
An exaggerated comparison is the 605A vs 605AS. Only difference is the blower diameter, but it's worth 1-2000m throttle height for a slight sacrifice in low alt power.
Given aerial combat height in the early-mid war in western Europe (particularly vs England) is rated at 5000-7000 metres (later goes upwards), it's really only coastal units, point defence interception and unlucky patrols that are running around at 3500 metres where the 601Aa is better. Even in the Med combat is 3000-6000 metres for the most part (typical transport sortie w/escort in 42 would have transports at 3-4000 and escorts at 5500).
Throughout the war it was noted fighter aircraft needed good performance at around 5000 metres, a lot of very good planes have their throttle heights here. Tempest, all the FWs, etc. And they're considered low alt fighters.
Klimov, the main Russian fighter engine had a throttle height around 3200m, even lower than the 601Aa despite two gears, but they had great take off performance for their horrible fuel grade (so low in Dec41 even around Moscow/Leningrad that it wouldn't operate Merlins without detuning and a local rebuild, which is why the first batch of Hurris got mostly stripped out for their equipment and Merlins never played a major role over there, the Allison handled poor fuels better...also meant one of their biggest supply demands was fuels, which Britain sent a lot of). But Russian fighters are a special case, production quality was so bad for a while that their performance band was only marginally above throttle height, later in the war it improved and gave them another 500m when they started keeping up with international standards on airframe quality (they weren't slippery enough in early production).
Don't mean to be distracting but it's a point that airframe quality plays a role here on performance heights too. As a very rough aside, if you want to have an idea how slippery an aircraft type was (build quality not just shape), compare its engine full throttle altitudes to its maximum level speed performance tables of a normal service example, the more apart they are the slipperier the plane.
True at takeoff the smaller blower gives better rpm and efficiency, so is worth about 75PS for 1min under 1000 metres. But that's the only place the Aa is better than the A-1 for outright performance.
Now the 601N, that gives you Aa take off performance at 5000 metres. That's why that motor was the bee's knees in 1940, but C2/3 is a very problematic fuel for long term use. Very corrosive I believe is the term IG Farben used.
The normal maximum rating of the 601A-1 is actually 1.3ata/2400rpm for 5min. During take off only (under 1000m) you could press it to 1.4ata at the same rpm but it rattled a lot and was under blower effiency height which is about 2000 metres.
The Aa blower lowers this to about 1500 metres maximum efficiency and helps it spin easier in thick air. Under 1000m the Aa will spin the 601 to 2500rpm/1.4ata instead of 2400rpm which is worth about 100hp.
But the lower throttle height is actually a reduction in performance. At 3800 metres the Aa puts out 1100PS military which is a little over 100hp more than the A-1, but at 4500m the A-1 puts out 1020PS military with good pressure and the Aa motor is dropping below 900hp and definitely out of breath. Maximum performance height for the airframe then rates at about 4200m for the Aa/Emil and about 5500m for the A-1/Emil, consider that typical frei-jäger in BoB is 7000m (because Spits lost climb rate at 6000).
Very loosely speaking comparing the A-1 to the Aa is very much like comparing a Merlin 45 to a 50. You do get higher maximums at low alt with a smaller blower that has a better efficiency down lower, but it really doesn't help you at fighter vs fighter combat heights, mostly for close ground support operations or escorts.
An exaggerated comparison is the 605A vs 605AS. Only difference is the blower diameter, but it's worth 1-2000m throttle height for a slight sacrifice in low alt power.
Given aerial combat height in the early-mid war in western Europe (particularly vs England) is rated at 5000-7000 metres (later goes upwards), it's really only coastal units, point defence interception and unlucky patrols that are running around at 3500 metres where the 601Aa is better. Even in the Med combat is 3000-6000 metres for the most part (typical transport sortie w/escort in 42 would have transports at 3-4000 and escorts at 5500).
Throughout the war it was noted fighter aircraft needed good performance at around 5000 metres, a lot of very good planes have their throttle heights here. Tempest, all the FWs, etc. And they're considered low alt fighters.
Klimov, the main Russian fighter engine had a throttle height around 3200m, even lower than the 601Aa despite two gears, but they had great take off performance for their horrible fuel grade (so low in Dec41 even around Moscow/Leningrad that it wouldn't operate Merlins without detuning and a local rebuild, which is why the first batch of Hurris got mostly stripped out for their equipment and Merlins never played a major role over there, the Allison handled poor fuels better...also meant one of their biggest supply demands was fuels, which Britain sent a lot of). But Russian fighters are a special case, production quality was so bad for a while that their performance band was only marginally above throttle height, later in the war it improved and gave them another 500m when they started keeping up with international standards on airframe quality (they weren't slippery enough in early production).
Don't mean to be distracting but it's a point that airframe quality plays a role here on performance heights too. As a very rough aside, if you want to have an idea how slippery an aircraft type was (build quality not just shape), compare its engine full throttle altitudes to its maximum level speed performance tables of a normal service example, the more apart they are the slipperier the plane.
True at takeoff the smaller blower gives better rpm and efficiency, so is worth about 75PS for 1min under 1000 metres. But that's the only place the Aa is better than the A-1 for outright performance.
Now the 601N, that gives you Aa take off performance at 5000 metres. That's why that motor was the bee's knees in 1940, but C2/3 is a very problematic fuel for long term use. Very corrosive I believe is the term IG Farben used.
Last edited:
Yes Vincenzo, two suggested reasons for this, speculative. One of them being hand machined Alfa versions rather than crate import motors. The other is atmosphere in the Med is thicker than over northern Europe. Its graded layers are each higher in respective altitude (earth's atmosphere bulges around the equator, thins over the poles). A European engine thinks it's flying lower than it is when in the Med. Affects tuning too.
as an aside, Rechlin quote different throttle heights for all 109s than Regensburg, often a band is quoted, eg. 605A 5.7-6.2km full throttle height (lower in Bremen, higher in Bavaria).
as an aside, Rechlin quote different throttle heights for all 109s than Regensburg, often a band is quoted, eg. 605A 5.7-6.2km full throttle height (lower in Bremen, higher in Bavaria).
Last edited:
AFAIKT Italian fuel was the same as German fuel. Italy has no great reserves of coal or oil then and now and any country with a limited supply of energy must struggle somewhat, Italy has of course a good climate to compensate, this might help prevent mass starvation and reduce reliance on food imports it doesn't produce panzers or fuel aircraft. Natural gas was discovered more or less in 1945 using a gravitometer supplied from Germany but it would be years before it could be exploited. Hitler didn't allocate too much fuel to the Italian military as he had analysed that his own troops could cause more damage to the enemy with that fuel. Certainly it tied the hands of he Italian military somewhat.
The Italian air cooled radials seem quite good though lacking in high altitude superchargers.
The Italian produced DB were good thouh they had to use ball instead of roller bearings in parts due to supply issues.
The Italian air cooled radials seem quite good though lacking in high altitude superchargers.
The Italian produced DB were good thouh they had to use ball instead of roller bearings in parts due to supply issues.
- Thread starter
- #33
Sagittario64
Airman 1st Class
For their time Italian radials were quite good. Italy had spent nearly its entire engine budget on radial engines as opposed to inlines. the supercharged engine for the Fiat CR.42 for example didnt shine because it was in a biplane, but it still gave the CR.42 a higher top speed than most if not all contemporary biplane fighters
Think you may make a short list of (radial) engines for 1940-43, say, top 3, or top 5 for each year. The engine of 840 HP will hardly quallify on any of those lists. If the A 74 was that good, the italian monoplanes with it would've been flying at least 350 mph, but that was not the case.
All aircraft engine that mattered were supercharged, so that adjective seems redundant.
teiresiasx
Airman
- 11
- Nov 4, 2009
According to Brotzu – Caso – Cosolo, Dimensione Cielo, Aerei Italiani nella Seconda Guerra Mondiale, vol. 3, Caccia Assalto, Rome, 1972, page 33 «*The DB's of the aircraft [i.e the bi-motor Ro. 58 at its maiden flight] are not those excellently license-built by Alfa Romeo and capable of developing up to 50 HP more than the original DB. They are instead old and worn out German built engines, which have only undergone a refitting...*»
- Thread starter
- #40
Sagittario64
Airman 1st Class
So are you saying that some Italian DB 601 powered aircraft were powered by former German engines and not Italian built ones? also on the service life note, how long were the service lives of Alfa Romeos as opposed to the Daimler benz engines?
