Fw190C technical question

[tomo pauk]

The actual difference is that engines with lower compression ratio will be able to withstand greater boost than other engines featuring higher compression ratio. More boost = more power.

 

[wiking85]

The actual difference is that engines with lower compression ratio will be able to withstand greater boost than other engines featuring higher compression ratio. More boost = more power.

A high compression ratio is desirable because it allows an engine to extract more mechanical energy from a given mass of air-fuel mixture due to its higher thermal efficiency. This occurs because internal combustion engines are heat engines, and higher efficiency is created because higher compression ratios permit the same combustion temperature to be reached with less fuel, while giving a longer expansion cycle, creating more mechanical power output and lowering the exhaust temperature. It may be more helpful to think of it as an "expansion ratio", since more expansion reduces the temperature of the exhaust gases, and therefore the energy wasted to the atmosphere. Diesel engines actually have a higher peak combustion temperature than petrol engines, but the greater expansion means they reject less heat in their cooler exhaust.

Higher compression ratios will however make gasoline engines subject to engine knocking if lower octane-rated fuel is used, also known as detonation. This can reduce efficiency or damage the engine if knock sensors are not present to retard the timing. However, knock sensors have been a requirement of the OBD-II specification used in 1996 model year vehicles and newer.

 

[tomo pauk]

Think you're comparing non-supercharged engine with

a supercharged engine tailored for reasonably high altitudes

where the increased CR is a liability, not an asset.

 

[GregP]

Manifold pressure is misnamed for a normally-aspirated engine. It is really manifold vacuum. The MP gauge on a normally-aspirated engine reads suction but is marked in numbers that don't make that obvious. If you haven't started the engine yet, then the manifold pressure gauge will read 29.92 inches of Mercury on a standard day at sea level.
That's 29.92 in HG absolute or 14.696 pounds per square inch or 1.000 atmospheres or 1.033 ata (technical atmospheres) or 760 mm Hg (or Torr). These are absolute pressures.

If you want to use gauge pressure, you subtract the 1 atmosphere from your reading so that on a standard day you have 0 in Hg gauge. So on a standard day the manifold pressure gauge for a normally aspirated engine will read 9.92 at sea level. It's hard to read the .02 part of the 29.92, but it will be VERY close to 29.9 inches of Mercury. If the sea-level airport has a big high-pressure area located over it with a local station pressure of 31.10, for example, then your gauge should show 31.1 inches of manifold pressure. If the airport is located at some higher elevation, the MP gauge will show an inch less for each thousand feet above sea level. (This rule-of-thumb is close enough at normal airport elevations, though it breaks down at altitudes above 10,000 feet.) You wouldn't want to use this rule of thumb in the Himalayas, for instance, at Bangda airport (15,548 feet MSL).

But, if you are at 6,000 feet and have 29.5" in the altimeter's Kollsman window, then you would take 29.5" and subtract 6 inches and would read close to 23.5" on the manifold pressure gauge before engine start.

Anything else is an error in the manifold pressure instrument. At that 6,000-foot airport, suppose it actually reads 22.5 (one inch too low), after you double check your procedure. That would indicate that for any power setting you want, you should set the MP one inch low to correct for that error.

In a normally-aspirated engine, the only thing that can move air through the induction system is the piston, traveling downwards, with the intake valve open! The piston sucks the air in, past the filter, past the throttle, past the venturi (on those engines so equipped), through the induction plumbing, and into the cylinder. The force to drive that piston down is supplied by either another piston on a power stroke, or the airflow past the prop in a dive with low power.

It should be clear from this that the intake system of any normally-aspirated engine is nothing more than a vacuum pump!

With the throttle plate closed (throttle lever fully retarded), the piston pulls (sucks) really hard, but simply can't move much air through or past the closed throttle. The engine is literally starving for air. What happens to the manifold pressure? Why it drops, of course, actually showing substantial suction (in other words, a lower pressure than the outside air). In most engines, idle MP will be around 12 inches or so, less than half the sea-level pressure. To look at it another way, the atmospheric pressure in the intake system (downstream of the throttle) of an idling engine at sea level is somewhere up around 20,000 feet. Thus the answer to one of the quiz questions: The most stress on an intake pipe is at idle, because it is trying to "implode." Of course, we're talking about only 8 PSI difference or so, and even a light aluminum pipe will take that with ease, so it's not a problem. You wouldn't want to use a soft rubber hose for an intake pipe, though!

If we could turn the engine fast enough, if the cylinders had perfect compression, and if the throttle plate could close off the induction system completely, we could create a perfect vacuum, which would show a manifold pressure of zero. Since all the numbers on the MP gauge are referenced to this theoretical perfect vacuum, we say that the MP gauge shows "Absolute Pressure."

At full throttle the engine can now get all the air it wants, with the only restrictions being the filter, the small area of the wide-open throttle plate (edge-on), and the turns in the ducting on the normal engine. Usually, those factors will cost you about an inch of MP, or a bit less. This is the answer to another quiz question as to why you'll see about an inch loss in MP during a full-power runup, just before brake release. During the takeoff and early climb, as the speed increases, a little bit of this loss is regained due to "ram effect" as the speed of the airplane literally rams more air into the induction system's air intake. At high airspeeds, some engines actually gain a little manifold pressure over ambient due to this ram effect.

Another key point. The intake system we're looking at has no idea what is taking place on the other side of that intake valve in the combustion chamber. It doesn't matter if there's "fire in the hole," or if the prop is windmilling in the breeze because an airline captain is talking nearby and pumping out the usual hot air, or the airplane is diving with the fuel shut off, engine not even running.

If that engine is turning for any reason, the pistons are hopping up and down, and every time one goes down with the intake valve open, it's sucking more air in. If the throttle plate is closed, it's sucking against resistance, creating suction that shows up as low MP; if the throttle is open, it's not blocking the airflow so manifold pressure remains equal to outside ambient (or perhaps an inch less due to unavoidable restrictions in the induction system).

The Rule: Manifold pressure depends on ambient pressure, the position of the throttle plate, and the speed at which the pistons are moving up and down. Manifold pressure does not indicate "power," unless other things are taken into account.

For a silly-but-true example, take an engine that is not running, and lift it from sea level to 18,000 feet. If the MP is 29 inches at sea level, it will be about 14.5 inches at 18,000. The change in MP is entirely due to the reduction in ambient pressure at altitude. Did the engine's power output change when the MP went from 29 inches to 14.5 inches? No, of course not -- it's zero either way.

Most of the above is from an article on AvWeb by John R. Deakin.

As for compression ratio, when the piston is at bottom dead center, the maximum amount of air-fuel mixture is in the cylinder. When it is at top dead center, the same amount of air-fuel mixture is compressed into the combustion chamber … which is the space above the piston when the piston is a the top of the stroke. Suppose the cylinder has 10 cubic inches of mixture in it at bottom dead center and 1 cubic inch when the piston is at top dead center. Then the compression ratio is then 10 : 1, which the ratio of the maximum volume to the minimum volume.

The real problem is you can only squeeze an air-fuel mixture so much before it detonates all by itself without the spark plug firing. So, if you boost the engine with a supercharger or turbocharger at sea level on a standard day, the manifold pressure will get to 29.92 plus whatever pressure the boost system supplies. If your boost system can supply another entire atmosphere, then you can see 2 * 29.92 or 59.84 inches of MAP (manifold absolute pressure) minus whatever small losses are present. I'd expect the MAP of such an engine at full throttle, sea level, standard day, to be about 58.5 - 58.8 inches MAP taking into account for real-world losses. It will drop about an inch per thousand feet up to 10,000 feet.

Anyway, if you load the cylinder with 58.8 inches of Hg (about 29.4 pounds per square inch) and then compress it 10 times (assume 10 : 1 compression ratio), that's 9 times the starting pressure (10 -1 = 9); 9 times 29.4 is 264.6 psi. The issue is whether the air-fuel mixture can stand that pressure before detonating.

That's a whole new subject. Higher-Octane or higher performance number (PN) fuels can be compressed more before detonation happens. For most 130 PN aviation fuels, detonation in WWII engine with a 6.0 : 1 compression ratio happened about 67 inches of MAP with ADI which is about +18.2 psi British boost and about 2.3 ata German boost. The fact that they were having issues as low as 1.8 ata suggests lower PN fuel was being used or the ADI was not being used. But we know they were using MW50.

That brings up the can of worms that is WWII German aviation fuels. It's another several posts and everyone has a different opinion.

 

[wiking85]

Think you're comparing non-supercharged engine with

where the increased CR is a liability, not an asset.

Why would things change if you maintained pressure?

 

[tomo pauk]

In an non-supercharged engine, there is no 'over-pressure' above the current atmospheric pressure. Basically, one never has more than 1 ata, or more than 29.92 in Hg in the intake manifold. If your car, powered with such an engine, is on the road that is located 5000 ft above sea level, it will have only some 87% of those 1 ata, or 0.87 ata. Same works for an aircraft that has no supercharging for it's engine. Here the increased CR will help, and some of the best aircraft engines of ww1 have had big CR to help out, like the BMW III.
Once supercharging entered the scene, enabling both greater altitude performance as well as increased manifold pressures to up the power, the reverse happens - great CR is more a hindrance than a benefit, since the detonation will happen earlier in a hi-CR engine than in a low-CR engine, due to greater increase in pressure temperature in the hi-CR engine.

 

[Koopernic]

Those two statements are at odds though, C3 fuel was only useful if you tune the engine to increased compression, which means a bigger bang and thermal load, plus stress on the engine parts, that would offset anything gained by slowing down the revolutions.

In a properly running engine there is no 'bang'. Normal combustion in a SI or Spark Ignition engine is known as deflagration. It is subsonic combustion of the mixture that precedes in an orderly wavefront out from the spark plug. If something goes wrong you might get 'detonation' which is simultaneous combustion and ignition at several or all points of the mixture. It is usually propagated by infrared radiation. The problem is often referred to as 'knocking' or 'pinging'. It will destroy the engine and it will also not produce much power. Another problem is preignition which is ignition of the mixture before the spark plug has sparked due to hot spots in the engine, poor cooling or left over end gases from the pervious cycle.

There are however disproportionately higher peak mechanical stresses which in fact can limit compression ratio, so your concern is to an extent correct though the CR at which it becomes a serious concern is about 12:1

A higher octane fuel inhibits both pre-ignition and detonation as they are related but not the same phenomena.

By increasing the compression ratio of an engine by fitting higher crowns to the pistons or 'shaving the head' (without changing its throw or swept volume) the hot gases of combustion are expanded over a greater relative distance and more energy (read more power) is extracted from the combustion. There is no additional thermal load since we haven't added any more or less fuel or air. In fact the overall thermal load is less since more of the heat has been extracted as mechanical power and the exhaust gas is cooler and doesn't need to be dealt with by the exhaust valves, exhaust plenum and the cylinder head, manifold or the radiators.

We do need a higher octane fuel.

For instance if we take a 2500hp Jumo 222A2/B2 and
1 Reduce RPM by 10% thereby reducing bearing stresses well as reducing some stresses by a square law.
2 Reduce Boost pressure by 10%n thereby further reducing mechanical stresses and reducing thermal load.

Please note boost, the amount of pressure used to force air/fuel mix into the engine by using the supercharger is different from compression ratio. Boost forces more air/fuel in but compression ratio only alters efficiency.

The primary problems the Jumo 222 had was ignition (read detonation) and bearing stress.

If we have C3 fuel available we might be able to avoid the ignition problems almost entirely. Alternatively we could increase the compression ratio of the engine, this would increase power for no extra cost in fuel or thermal load but we could lower the boost and RPM further to maintain the same power levels but achieve reduction in thermal load.

C3 fuel gives you much more options.

C3 fuel does not require increase in compression ratio; increasing the CR is a self inflicted wound that, indeed, increases thermal load and stress on engine parts. snip.

I don't believe you understood this quite right way I said it.

If you increase compression ratio by using a higher octane fuel but keep swept volume the same you extract more energy from the air fuel mixture, ergo the average temperature in the combustion chamber is less and you have less thermal load but also more power. Its a win win situation.

Hi tomo,
i believe that by 20% derated jumo222., he means from 2500 ps down to 2000ps, not from 2000 to 1600 ps
And indeed ,in 1942, a 2000ps,1080 kgr jumo 222 would be extremely useful for the ju88 family, and the do217
However c3 is out of the question for a LW bomber. Even the Bmw s 801 when used on bombers had b4 fuel and reduced horsepower
I feel , of course i am just an amateur, the problems of the ju222 were more of political nature than technical
Kurt tank, in 1942, did propose the serial production of the Fw190C, in the form of the non turbosupercharged V13-V16 prototypes.
RLM rejected the proposal.Despite the problems of the db 603 in 1943, its quite reasonable to expect initial service for the Fw190C in september 1943 and full servise by early 1944. Of course that means cancel the me410.
But the main influence in RLM decisions was not of technical nature. The simply did not want ANY delay of production.They refused even improvements to the standart fighters , let alone introduce radical diferent subtypes. They kept producing obselete vertions of the 109 and 190 in order not to delay the production. Today we know the disastrous results of this policy. Not only the Fw190C was victim of this. The FW190D and Ta152A were almost ready for production in the spring1944 and still, the rlm delayed their production another 6 months.
My opinion is that the installation of the db 60A in the light Fw190A4 airframe with c3 fuel and an armament ofm 3 MG151s, would result in a formidable air superiority fighter until 8000m. With future use of the db603EM would be formidable until the very last day of the war.

That is precisely what I meant, a 2000hp version of the Jumo 222 would come in useful for the Do 217, Ju 88S and G, Ju 188 and He 219 although it might be a little weak for the Ju 288B.

Agreed that large quantities of C3 fuel is not possible for the Luftwaffe though the refinery infrastructure in the form of alkylation plant was coming on line in 1943 or so. However a 2000hp Jumo 222 might be possible on B4 or small runs of the engine could be mad to run of C3 and then progressed to B4+MW50 for takeoff power.

The Jumo 213B and C were to be able to use C3 fuel for greater power, the C version had a propeller suitable for a motor canon. These were single stage supercharger engines roughly equal to the 1750hp Jumo 213A. It should have been relatively easy to get to 1900hp with these engines with C3 fuel and this is the rating that allowed the Fw 190D9 to become viable (1900hp with increased boost using B4 fuel)

The Fw 190D9 was handicapped by being equipped with a bomber engine left over from the Ju 188 programme. It lacked in built boost systems and mountings for a motor canon capable propeller, the surplus engine blocks had to be used up though.

 

[EKB]

Hi tomo,
Despite the problems of the db 603 in 1943, its quite reasonable to expect initial service for the Fw190C in september 1943 and full servise by early 1944. Of course that means cancel the me410.

The Germans were better off canceling the DB603. All of their liquid cooled combat aero engines were unreliable by that time. Less dependable with every month that passed and it was not possible to reverse the trend.

 

[tomo pauk]

Please note boost, the amount of pressure used to force air/fuel mix into the engine by using the supercharger is different from compression ratio. Boost forces more air/fuel in but compression ratio only alters efficiency.

Bingo.

The primary problems the Jumo 222 had was ignition (read detonation) and bearing stress.

Depends what one reads. 'Flugmotoren und strahltriebwerke' mention a host of other problems, each serious on its own.

I don't believe you understood this quite right way I said it.

If you increase compression ratio by using a higher octane fuel but keep swept volume the same you extract more energy from the air fuel mixture, ergo the average temperature in the combustion chamber is less and you have less thermal load but also more power. Its a win win situation.

A win-win situation assumes that TANSTAFL does not apply, and we know that it always applies. The compression ratio can't be increased by using the higher oct fuel, it is increased by change in pistons (like it was the case in BMW 801C -> 801D development) in most of the cases. Extracting more eneragy in a piston engine means that thermal load is increased.
We can recall that most of the times DB introduced a hi-CR engine (601N, 605A, 603A), it took plenty of time for the engines to develop the 'paper' power. The BMW 801D was de-rated for 7 months when introduced, CR was increased
Now I wan't go that far to say that increased CR was the sole root of the issues, but tendency is there. The DB 605A have had realiability issues already with 7.5/7.3:1 CR, it took DB some 15 months so cure the situation. Same (worse?) with Db 603A, while the DB 601N never went beyond 1.35 ata with C3 fuel.

The Jumo 213B and C were to be able to use C3 fuel for greater power, the C version had a propeller suitable for a motor canon. These were single stage supercharger engines roughly equal to the 1750hp Jumo 213A. It should have been relatively easy to get to 1900hp with these engines with C3 fuel and this is the rating that allowed the Fw 190D9 to become viable (1900hp with increased boost using B4 fuel)

The Jumo 213C was just the 213A with provision for engine cannon.

The Fw 190D9 was handicapped by being equipped with a bomber engine left over from the Ju 188 programme. It lacked in built boost systems and mountings for a motor canon capable propeller, the surplus engine blocks had to be used up though.

Any handicap the D-9 had didn't stem from the jumo 213A being a 'bomber engine'. 1st handicap is that it came out too late. The absence of provision for engine cannon does not prevent the Fw to install 4 cannons on the D-9 (while preferably deleting the cowl HMGs in the same time). The 'built in boost systems' will not help above 7 km, where the major action was above Germany from late 1944 on, and it was easy enough to use C3 or MW 50 on the Jumo 213A anyway.

 

[dedalos]

Bingo.



Depends what one reads. 'Flugmotoren und strahltriebwerke' mention a host of other problems, each serious on its own.



A win-win situation assumes that TANSTAFL does not apply, and we know that it always applies. The compression ratio can't be increased by using the higher oct fuel, it is increased by change in pistons (like it was the case in BMW 801C -> 801D development) in most of the cases. Extracting more eneragy in a piston engine means that thermal load is increased.
We can recall that most of the times DB introduced a hi-CR engine (601N, 605A, 603A), it took plenty of time for the engines to develop the 'paper' power. The BMW 801D was de-rated for 7 months when introduced, CR was increased
Now I wan't go that far to say that increased CR was the sole root of the issues, but tendency is there. The DB 605A have had realiability issues already with 7.5/7.3:1 CR, it took DB some 15 months so cure the situation. Same (worse?) with Db 603A, while the DB 601N never went beyond 1.35 ata with C3 fuel.



The Jumo 213C was just the 213A with provision for engine cannon.



Any handicap the D-9 had didn't stem from the jumo 213A being a 'bomber engine'. 1st handicap is that it came out too late. The absence of provision for engine cannon does not prevent the Fw to install 4 cannons on the D-9 (while preferably deleting the cowl HMGs in the same time). The 'built in boost systems' will not help above 7 km, where the major action was above Germany from late 1944 on, and it was easy enough to use C3 or MW 50 on the Jumo 213A anyway.

Hi tomo,
I dont believe that the high CR was the problem for the german engines. I firmly believe that the root problem ,once again, was the lack of raw materials to produce strong alloys and the all time pressure to speed up production.
You are correct that lowering CR would permit more supercharger boost but could the structural elements take the additional mechanical amd thermal loads? Could the german metallourgy keep up without acces to certain raw materials?
Maybe they could bypass the problems by alternate solutions but then met the second problem : Not to disturb production. So the disastrous decision not to push in time with two stage superchargers. After that it was hopless. There was no way for the german fighters to be competitive over germany regadless the CRs and boosts
And notice that the jumo 213, which have lower cr than the db603, was not also fully reliable.At least until december 44.And i am sure you know the problems of the jumo 213E with the third speed of its superchrger. And also despite its lower CR did not use that much higher bosst

Look at the D9. Despite the fact that the Jumo 213 was actually lighter than the Bmw 801, dora was as heavy despite the fact that it carried two less 20mm guns! Why? To speed up production they required the power egg. That produced weight in front.To restore CG could slightly modify the wings but they prefered the easier to produce longer rear fuselage . Which added more weight. At the end the initial superb Fw190C had transormed to the Fw190D9 which-at least initially- was little better than the 3 years old A-series

The lack of raw materials was also a problem for germany in WW1. And their engines were less powerful than the French or british engines. However by careful designing and decision making they managed to produce the Fokker DVII and DVIII, and the Siemens DIV, fighters extremely formidable and at least on par with the french and British fighters. At the end only Numerical inferiority made the difference. In ww2, really BAD leadership crippled the Jagdwaffe( Not that would win otherwise)

 

[tomo pauk]

Hi tomo,
I dont believe that the high CR was the problem for the german engines. I firmly believe that the root problem ,once again, was the lack of raw materials to produce strong alloys and the all time pressure to speed up production.

The high CR was surely a far less of a problem than, say, too late interoduction of engines with improved superchargers or with too late introduction of bigger engine 'line' (DB 603, Jumo 213A). The strength of, say, DB 601/605 line of engines seem to be on par with equally heavy (or light) later Merlin and V-1710 engines IMO. Quirk with high CR is that it brings more shortcomings than benefits, not just with requiring ADI (MW 50 in LW case) in order to come close to manifold pressures most of the Allied engines were making without ADI.

You are correct that lowering CR would permit more supercharger boost but could the structural elements take the additional mechanical amd thermal loads? Could the german metallourgy keep up without acces to certain raw materials?

As above - neither German engine that was in service looks like a flimsy job. From DB 601/605 vs. Merlin and V-1710, to Jumo 213 and Db 603 being equally heavy and of comparable power with Grffon etc.

Maybe they could bypass the problems by alternate solutions but then met the second problem : Not to disturb production. So the disastrous decision not to push in time with two stage superchargers. After that it was hopless. There was no way for the german fighters to be competitive over germany regadless the CRs and boosts

No doubt that any change will involve hiccups in production lines. But - leaving the LW (or any other) pilots to fly in 1944 with fighters that have less performance than ones from 1942 (despite some increase in engine power, performance drop was due to increased armamament and armor installed) will make them dead, and no one can produce pilots in factories.

And notice that the jumo 213, which have lower cr than the db603, was not also fully reliable.At least until december 44.And i am sure you know the problems of the jumo 213E with the third speed of its superchrger. And also despite its lower CR did not use that much higher bosst

Both Jumo 213A and 213E were supposed to make 2 ata on B4 and MW 50; the DB 605D was at 1.8 ata with B4 and MW 50 (or 1.98 ata with C3 and MW 50), while the DB 605L was at 1.75 ata with C3 and MW 50. Not just that, the duration was to be 30 min for that kind of power vs. only 5 min for the DB 605 line.
The development of the 213 engine started the last, looking at other major German engines. Asking from it to perform flawlessly from day one would be asking too much, especially if we take a look at long gestation periods of many DB engines and the BMW 801 series.

Look at the D9. Despite the fact that the Jumo 213 was actually lighter than the Bmw 801, dora was as heavy despite the fact that it carried two less 20mm guns! Why? To speed up production they required the power egg. That produced weight in front.To restore CG could slightly modify the wings but they prefered the easier to produce longer rear fuselage . Which added more weight. At the end the initial superb Fw190C had transormed to the Fw190D9 which-at least initially- was little better than the 3 years old A-series

The D-9 was not an ideal plane, but again - it's main shortcoming was the timing. The decision to use fuselage HMGs will cost 10 km/h, or thereabout, something the early Antons lacked. The drag of 2 x MK 108 was to cost the same in speed, while adding to the punch immensely; the D-9 with 4 cannons and no cowl HMGs will maybe do 690 km/h without overboost, and 705 km/h with?
We need to add the weight of the cooling system of a liquid cooled engine, in order to compare the weight with air cooled engine, an that puts the Jumo 213A and BMW 801D in the ballpark.

 

[dedalos]

The high CR was surely a far less of a problem than, say, too late interoduction of engines with improved superchargers or with too late introduction of bigger engine 'line' (DB 603, Jumo 213A). The strength of, say, DB 601/605 line of engines seem to be on par with equally heavy (or light) later Merlin and V-1710 engines IMO. Quirk with high CR is that it brings more shortcomings than benefits, not just with requiring ADI (MW 50 in LW case) in order to come close to manifold pressures most of the Allied engines were making without ADI.

Still,junkers in its efforts for further power gains was researching higher CR in combination with C3 fuel among other ideas.
Merlin never had the problems of the 605 during the mid war years



As above - neither German engine that was in service looks like a flimsy job. From DB 601/605 vs. Merlin and V-1710, to Jumo 213 and Db 603 being equally heavy and of comparable power with Grffon etc.



No doubt that any change will involve hiccups in production lines. But - leaving the LW (or any other) pilots to fly in 1944 with fighters that have less performance than ones from 1942 (despite some increase in engine power, performance drop was due to increased armamament and armor installed) will make them dead, and no one can produce pilots in factories.



Both Jumo 213A and 213E were supposed to make 2 ata on B4 and MW 50; the DB 605D was at 1.8 ata with B4 and MW 50 (or 1.98 ata with C3 and MW 50), while the DB 605L was at 1.75 ata with C3 and MW 50. Not just that, the duration was to be 30 min for that kind of power vs. only 5 min for the DB 605 line.
The development of the 213 engine started the last, looking at other major German engines. Asking from it to perform flawlessly from day one would be asking too much, especially if we take a look at long gestation periods of many DB engines and the BMW 801 series.

I am surprised aboout this statement. The power settings that i know for the jumo 213 are
Climb and combat 1620PS 1,4ata
take off and emergency 1750ps 1,5 ata
increased emergency 1900ps 1,7 ata
MW 50 special emergency 2100 ps 1,78 ata
I must add that today there are doubts that the average Jumo 213 could actually deliver these performances
2,03ata would be the mythical 2240 ps setting which certainly required C3 plus MW50. However , as far as i know, such D9 never existed in reality, even on test fields.And you speak for 2,3 ata on B4 (!!!) plus Mw50. If you have new informations please share them with me
I do have read unreliable reports that a few operational D9s did use C3 which resulted in good performance gains but i have been unable to confirm them


The D-9 was not an ideal plane, but again - it's main shortcoming was the timing. The decision to use fuselage HMGs will cost 10 km/h, or thereabout, something the early Antons lacked. The drag of 2 x MK 108 was to cost the same in speed, while adding to the punch immensely; the D-9 with 4 cannons and no cowl HMGs will maybe do 690 km/h without overboost, and 705 km/h with?
We need to add the weight of the cooling system of a liquid cooled engine, in order to compare the weight with air cooled engine, an that puts the Jumo 213A and BMW 801D in the ballpark.

I dont believe in the need of the wing cannins.2x20mm with 250rpg near the center line is enough for antifighter operations.
Against bombers use R4M rockets. Better use the wing space for fuel tanks.
Speeds near the 700km/h ,in my opinion , was out of reach of the average D9 due to inferior building quality of both the engine and the airframe

There is very big distance between reports of operational D9 pilots. Early examples in JG26 disappointed the pilots. Later some,eg dortemman , loved it
Oskar Romm liked it. Barkhorn did not like it.Rescke reports that was better than anton at altitude but still sufferd heavy casualties in JG301. In JG 51 the pilots liked it.
Some russians claimed that iit burned like any other FW, still other had great respect and fear for it
Russian test pilots were unimpressed (they did admit that flew without MW50) Eric brown was impressed and placed near the Spit XIV
Operationaly suffered heavy casualties against western fighters yet in test flight against a tempest with a good pilot at cocpit performed well
Go figure where the truth lies

 

[tomo pauk]

Still,junkers in its efforts for further power gains was researching higher CR in combination with C3 fuel among other ideas.
Merlin never had the problems of the 605 during the mid war years

Unlike the DB 601/605, Merlin did not change the working displacement, nor the CR, nor the max RPM; eg. increase of RPM by 10% increases stress of not just moving parts of engine by 21% (goes up by square of RPM increase). The increase of boost (where Merlin excelled) will increase the stress in a linear fashion, however.
Jumo indeed was looking for CR of 8.5:1 for the Jumo 213E fueled with C3, per 'Flugmotoren strahltriebwerke'. The gain in power was supposed to be around 10%, per black-ish chart found at Kurfurst's.

I am surprised aboout this statement. The power settings that i know for the jumo 213 are
Climb and combat 1620PS 1,4ata
take off and emergency 1750ps 1,5 ata
increased emergency 1900ps 1,7 ata
MW 50 special emergency 2100 ps 1,78 ata
I must add that today there are doubts that the average Jumo 213 could actually deliver these performances
2,03ata would be the mythical 2240 ps setting which certainly required C3 plus MW50. However , as far as i know, such D9 never existed in reality, even on test fields.And you speak for 2,3 ata on B4 (!!!) plus Mw50. If you have new informations please share them with me

I did not mentioned the 2.3 ata anywhere; if I did, that is a mistake. The 2.02/2.03 ata bost is noted in this chart.

I dont believe in the need of the wing cannins.2x20mm with 250rpg near the center line is enough for antifighter operations.
Against bombers use R4M rockets. Better use the wing space for fuel tanks.
Speeds near the 700km/h ,in my opinion , was out of reach of the average D9 due to inferior building quality of both the engine and the airframe

The initial D-9 were not able to match the expected performance, since the cowling/fusealge gap was present, unlike with the wind tunnel model, while the 1st Jumo 213A were encountering supercharger problems, at least by this page.
LW needed, at least from mid 1943, a fighter that has performance close to the Anglo-American best, as well as armament to kill bombers. R4M rockets were not a done deal by early 1944, the cannons were, hence my proposal to delete cowl HMGs and have cannons instead. Of course, for operations that require long range, the wing tanks are a fine option (but self-sealing ones, not what was installed on Ta 152).

 

[dedalos]

Unlike the DB 601/605, Merlin did not change the working displacement, nor the CR, nor the max RPM; eg. increase of RPM by 10% increases stress of not just moving parts of engine by 21% (goes up by square of RPM increase). The increase of boost (where Merlin excelled) will increase the stress in a linear fashion, however.
Jumo indeed was looking for CR of 8.5:1 for the Jumo 213E fueled with C3, per 'Flugmotoren strahltriebwerke'. The gain in power was supposed to be around 10%, per black-ish chart found at Kurfurst's.



I did not mentioned the 2.3 ata anywhere; if I did, that is a mistake. The 2.02/2.03 ata bost is noted in this chart.



The initial D-9 were not able to match the expected performance, since the cowling/fusealge gap was present, unlike with the wind tunnel model, while the 1st Jumo 213A were encountering supercharger problems, at least by this page.
LW needed, at least from mid 1943, a fighter that has performance close to the Anglo-American best, as well as armament to kill bombers. R4M rockets were not a done deal by early 1944, the cannons were, hence my proposal to delete cowl HMGs and have cannons instead. Of course, for operations that require long range, the wing tanks are a fine option (but self-sealing ones, not what was installed on Ta 152).

Interesting chart
What horsepower would result with 2,03 ata? Was this an operational setting?
However , even with 2,03 ata, the D9, according to this chart can not reach 700km/h at any altitude
How you explain the fact that junkers was looking to take advantage of the c3 properties, not by additional boost but by higher CR?
Perhaps were trying to raise further the full throtle height?

 

[tomo pauk]

Interesting chart
What horsepower would result with 2,03 ata? Was this an operational setting?

Looks it was possible to extract 2240 PS from the 213A, per this table at AEHS (other interesting tables and photos of some German engines are here). The Jumo 213E/B is listed as a modification of the 213E with CR increased to 8.5:1, 2250 PS with MW 50, there is no fuel listed, though. Jumo 213E was at 2050 PS with B4 and MW 50 (on 1.92 ata??).
The plain vanilla 213A was supposed to do indeed 2100 PS at SL, per this chart.
Hopefully the proud owners of the book about Junkers engines will shed some light about this topic.

It will be interesting to note, looking at the pictures at AEHS, that one of 1st German 2-stage engines of ww2, the DB 628, actually featured an air-to-air intercooler.

However , even with 2,03 ata, the D9, according to this chart can not reach 700km/h at any altitude

It can on this table But then, I won't argue about 5 km/h here or there. Even 680-690 km/h is quite a speed for a fully combat-capable ww2 aircraft with a single stage engines, and Fw was trying to further improve the capabilities of the 190 line (despite the introduction of the Ta 152) with installation of non-intercooled two stage Jumo 213F in D-12.

How you explain the fact that junkers was looking to take advantage of the c3 properties, not by additional boost but by higher CR?
Perhaps were trying to raise further the full throtle height?

Looking at the chart from Kurfurst, the full throttle height(s) was to be same for 213E and 213E/B (213EB?); the FTL(s) was (were) anyway already respectable. The 213E with a higher compression ratio probably need bulking-up of some components if same boost is to be used as on the 213E with 6.5:1 CR - as above, any good info about the 213 line of engines is more than welcome.
We know that Jumo was also working on much modified 213J (slightly inreased bore/displacement, 4 valves per cylinder, up to 3700 rpm(!), only 2-speed supercharger), so the 213E with increased CR was not their only bet. Plus the 213F, a '213E minus' if you like, probably a little more easier to install on the Doras instead of 1-stage 213A.

The chart showing the 213A making 2250 PS on SL; B4 and MW 50:

 

[Denniss]

The chart above is for the engine with 1900PS base setting, already running with increased boost. Likely pushed to the limit of what B4 was capable of with Methanol-Water injection.

 

[awack]

I must add that today there are doubts that the average Jumo 213 could actually deliver these performances
2,03ata would be the mythical 2240 ps setting which certainly required C3 plus MW50. However , as far as i know, such D9 never existed in reality, even on test fields.And you speak for 2,3 ata on B4 (!!!) plus Mw50. If you have new informations please share them with me
I do have read unreliable reports that a few operational D9s did use C3 which resulted in good performance gains but i have been unable to confirm them
There is very big distance between reports of operational D9 pilots. Early examples in JG26 disappointed the pilots. Later some,eg dortemman , loved it
Oskar Romm liked it. Barkhorn did not like it.Rescke reports that was better than anton at altitude but still sufferd heavy casualties in JG301. In JG 51 the pilots liked it.
Some russians claimed that iit burned like any other FW, still other had great respect and fear for it
Russian test pilots were unimpressed (they did admit that flew without MW50) Eric brown was impressed and placed near the Spit XIV
Operationaly suffered heavy casualties against western fighters yet in test flight against a tempest with a good pilot at cocpit performed well
Go figure where the truth lies

I got about the same info as you. The books ive read on the 190/152 say that the 190D9 could use either b4 or c3 fuel, ive read once and only once..is that the top cover d9s of JV 44 used C3 fuel, no way of knowing for sure, but a unit with Galland, bar and Steinhoff, should be able get what they want, considering the Circumstances of course ,

I have always wanted to know the true performance of the D9, since it along with the Spitfire XIV, P 51 and Tempest V (ta 152 H1, only 47 or so built) since most spec for aircraft are either estimates or catalog specs, we have statements from Clostermann along with another Tempest pilot who said similar things about the 190 D9, the pilot whos name escapes me said about a combat that took place at around 3300 ft against a D9 he didn't mention speed but he said that the tempest cold out dive the D9, but the D9 could out roll him, had a smaller turn radius, and def that the D9 had the better climb, which surprised me at that altitude, combat reports are def not the most accurate, but there seems to be some agreement.

When it comes to how the D9 fared over all in air to air combat, the thought seems to be that it did very well in Russia and that it didn't do as well in western Europe, which makes sense, many D9 pilots, were under trained to put it nicely, but ive only read two combat reports that takes into account, both the Allied and German perspective, one was a combat with P47s, one P47 was shot down initially in a head on pass, and one D9 shot down from behind, the other includes combat with tempest where two Tempest shot down one of them described as the top tempest pilot, one D9 was shot down. By the way, the P47 pilot went on to fly a Fw 190 after the war and said it was almost unbeatable in the vertical, he had flown the p51, spitfire, p47 and somethen else, but interestingly, he did not mention ever flying the Tempest, which I believe is the best prop allied energy fighter...this is just two accounts which don't tell the whole story, as I believe the D9 being equal to the best allied fighters plus with under trained pilots wouldnt have been any kind of threat to the allies, there was only one operational aircraft on the planet that could challenge the huge bomber armadas and that was the me 262, with its speed, climb, dive, handling acceleration and fire power.

Oh just saw a walter krupinski video talking about air craft he flew, he had flown late 109s like the K4s, he flew top cover for 190s I believe, he seems to think that the D9 was the best prop fighter in the Luftwaffe due to its speed and very good maneuverability, cockpit lay out and visibility.

And yeah, Eric Brown originally placed the D9 2nd to the Spitfire XIV, later he said he had to fight his own bias and rank the D9 and Spitfire XIV equal at number 1, with the 262 being in completely different league. My own opinion is that the XIV, D9 P51 and Tempest V were all roughly equal, I could be completely wrong.

I have seen a chart dated 21-2-45 showing the rate of climb 190 D9 using C3 fuel, 2.02 ata, no etc 504 rack and weighing 9413 pounds..sea level climb is around 4700 fpm or just above that at 4730 fpm, a bit better than the 4390 fpm for the D9 at 1.8 ata using B4 fuel.This is supposedly a standard production aircraft with 2x13mm and 2x20mm guns.

Wow, ive just seen a German document dated 19-3-45, showing FW 190 D9s of II/JG6 using or at least cleared for use of C3 fuel, I have heard many times that a stab or something like that used C3 fuel in combat and im pretty sure ive found it, for others who might be interested, most units by this date seem to be using 190 A9s as apposed to A 8s using C3 fuel, there are three Me 109 K4 unit on the list all are using or are cleared for B4 fuel, I know there is a lot of controversy about K4s and what fuel it used. Now just need to get the top speed for the D9 using C3 fuel.