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Old 03-09-2015, 10:10 AM   #141
Kurfürst
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Quick and dirty of course and I am missing the boosted output of the BMW 801 here (2100 PS at SL IIRC), whereas the Jumo curve is for full boost, with MW -50. The normal output was around 1770 PS.

At lower altitudes there is some advantage of the 213 of course, largely due to its more efficient supercharger handling (no see-saw curve), which should show itself between 2-4 km range mostly... However it is seen that actually above rated altitude, ie. 6000+ m for both engines, the two engines are almost perform the same, despite the common myth that the Jumo 213 somehow improved the poor altitude performance of the BMW 801D. It simply didn't, where it improved over it was the much smaller cross setion and smaller drag of the engine installation. So at least at higher altitude practically all of the performance increase is due to the lower drag of the D-9 compared to the A airframe IMO.

EDIT: Added a rough estimate of C-3 injection boosted BMW 801 power levels
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Old 05-01-2016, 05:14 PM   #142
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Originally Posted by Nate--IRL-- View Post
I love this stuff, don't understand much of it, but I love it.

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Learn to understand it, and you'll love it more

These engines have a supercharger, a device that compresses the outside environment's air to above normal atmospheric pressure, so more air fits into each cylinder, so more fuel can be burned, increasing horsepower.

These graphs show:

-Engine power produced for a given air intake ('boost') pressure, and how this power output decreases as altitude increases (because the atmospheric air pressure decreases as you go higher, and the supercharger eventually loses its ability to compensate for that at higher altitudes.)

-Specific fuel consumption, which is the amount of fuel burned per hour, per horsepower produced. The higher the HP output, the dis-proportionally worse the 'gas mileage', but the better the acceleration, climb, & top speed. The airplane's range is shortened at higher power levels.

These 'ancient' WW2 piston engines (from all countries involved) were *incredibly* well understood and very highly developed for their time. People that tinker with cars today that have turbos, superchargers, 4-valve heads, etc. etc. and think they have something "high tech" are playing with 70 year old technology

In the 1930s and 40s, the P-51 was today's F-18, the Bf-109 was an F-16, and the Fw-190D-9 was an F-22
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Old 05-02-2016, 09:51 AM   #143
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Originally Posted by Kurfürst View Post
Quick and dirty of course and I am missing the boosted output of the BMW 801 here (2100 PS at SL IIRC), whereas the Jumo curve is for full boost, with MW -50. The normal output was around 1770 PS.

At lower altitudes there is some advantage of the 213 of course, largely due to its more efficient supercharger handling (no see-saw curve), which should show itself between 2-4 km range mostly... However it is seen that actually above rated altitude, ie. 6000+ m for both engines, the two engines are almost perform the same, despite the common myth that the Jumo 213 somehow improved the poor altitude performance of the BMW 801D. It simply didn't, where it improved over it was the much smaller cross setion and smaller drag of the engine installation. So at least at higher altitude practically all of the performance increase is due to the lower drag of the D-9 compared to the A airframe IMO.

EDIT: Added a rough estimate of C-3 injection boosted BMW 801 power levels
I'm curious as to how the C-3 injection worked. As I understand it the 801 already ran on C-3 fuel, so the only reason I can think of for injecting more of it would be that the engine is capable of burning more fuel than the original injection system could provide. Obviously the additional fuel would also carry some charge cooling effect, but that is useless if you end up making the mixture so rich that the engine loses power.

Am I on the right track here?
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Old 05-02-2016, 10:44 AM   #144
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Nerd right track C3 Fuel was injected in the supercharger the spray cool down the intake air with that engine can run more rich and produce more power.
MW50 had on the 801 Radial engine much impact in reduce life span, and the more Power output was marginal.
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Old 07-31-2019, 08:28 PM   #145
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Originally Posted by Nerd1000 View Post
I'm curious as to how the C-3 injection worked. As I understand it the 801 already ran on C-3 fuel, so the only reason I can think of for injecting more of it would be that the engine is capable of burning more fuel than the original injection system could provide. Obviously the additional fuel would also carry some charge cooling effect, but that is useless if you end up making the mixture so rich that the engine loses power.

Am I on the right track here?
I might be necrothreading a bit but it's a poorly understood subject so worth stating.
The C3 injector and MW50 boost systems aren't about C3 or MW50 at all, in fact ideally neither would be required for what is being achieved by them.
It's all about over boosting the engine supercharger to accomplish higher than normally rated power outputs. Nothing to do with injecting anything, all about over boosting the blower.

This was a common practise for supercharged aircraft before boost regulators became normally fitted, for example the P40E doesn't have a boost regulator, so the pilot has to carefully manage the throttle below critical altitude or damage the engine with too much boost. This is because the throttle gives maximum boost at critical altitude, air is more dense at lower altitude, so the maximum boost is exceeded below critical altitude unless you have a boost regulator fitted, like a P40M. That one you can shove the throttle to its gate at take off and simply get maximum emergency power, try it in a P40E and you'll hit about 1900hp for half a second and explode the engine. Without a boost regulator you have to watch what you're doing with the throttle under critical altitude, hence it's called critical altitude because you need to be wary under it and not sad altitude because you lose boost above it. That's the way I like to think about it anyway.

Okay so the common practise was to richen the mixture a little too much for normal running and push the throttle a little too far forward, exceeding maximum listed manifold pressure, to exceed normal maximum outputs for a short period, 1-2 minutes tops. But then by midwar pretty much every aircraft had auto mixture and boost regulators so you couldn't do it without a built in override facility or mechanical adjustment, but it probably saved a lot of fighter engines from excited cadets. Simple version is you couldn't do it so easily once a lot of a/c management became automated or semi automated, but it was a common practise when everything was so manual the pilot had to spend more time looking at instruments than they could looking for e/a and broken engines in those days were very common indeed.

An example of this is the RAF operating P40E at 1670hp in North Africa and RAAF actually getting 1720hp from theirs by significantly over boosting using high grade fuels, documented by Allison Engineering in wartime correspondence records. Quite a bump from the 1150hp rated output. It was a letter advising against its continued practise as exceeding manufacturer operating procedure and dangerous for forthcoming engine type production, although Allison was apparently quite pleased their engine stood up better than their expectations in the field.

Adding a charge coolant injector obviously alters this field improvisation of boosted power to one of manufacturer installation under tested guidelines. Initially these did the same thing pilots used to do on their own initiative, ie. a modest boost increase for a very limited duration of 1-2 minutes before holing the pistons. With further development, improvements to the intended engine in chambering and so forth specific to the modification, by 1944 over boosting with a charge coolant got you up to ten minutes of continuous, significant over boost and power increase in hundreds of horsepower, without breaking the engine.

This took time to develop using synthetic fuels, Daimler worked closely with IG Farben to develop combustion chambering throughout the war, their original 1940 goal of 2bar over boost and 1.5bar military power in the forthcoming 605 engine was never actually achieved until the D motor of late44 (and 1.85ata was the best they got on B4). One way of cheating was to hotrod an engine with C3 (or C2) fuel like the 1940 601N motor, Daimlers normally run on B4 so the higher knock rating allowed a limited over boost for 1-2mins. But the BMW 801D already ran on C3 so unless you were going to run it on alcohol you couldn't really hotrod it.

Now the 801D2 was intended from the beginning of production to use MW50/over-boost kits but these weren't available from their manufacturer until February 1944 for whatever reasons. In the meantime Focke Wulf wanted a cheat for the FW190G to give over boost at low altitude for its schnellbomber mission role, which in modern terms you might call deep penetration strike. These were sent in raids against the British coast in 43 and had to outpace Spitfires by the dozen for any chance at survivability. So came the C3 injector, which also tended to find its way into the F series.

German engines use direct injection after the blower compresses raw air, which gets quite hot and throws out the mixture when you over boost. Boost enrichening is normally incorporated into factory tuning but when you over boost you go beyond normal tuning. Not such a big deal in a carb motor like the Merlin, which compresses a fuel-air mixture and can probably get away with manual mixture adjustment to compensate but a real problem in a German engine compressing raw air and then adding pre-calculated fuel metering that didn't have over boost in mind.
The C3 injector just adds an extra fuel injector to the supercharger intake for boost enrichment and it helps a little with charge cooling compared to compressing raw air. The over boost it can withstand is limited but there.

The MW50 is piped to the supercharger exhaust and uses a completely different set of playing rules, the direct injection itself is retuned for over boost enrichment and the injector just cools raw air coming out of the compressor. It allows significant over boost for long periods.

The FW190 radials got MW50 from February 44. The G and F had a much more limited C3 injector over boost before then.
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Old 08-01-2019, 07:23 AM   #146
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Injection of c3 fuel added cooling effect on copressed air, another thing aditional fuel decreased AFR even more allowing increase MP w/o danger to the engine. Engines at high power settings were running at about 10-11 AFR
lower AFR highest boost allowed if under high boost from some reason AFR jumps up it may overheat piston make it expand too much making damage to cylinder liner wall.
in some cases piston can melt but melting is extreem. so engine even reciving such a damage can still work ofc it will burn oil like crazy but it is still far from sezuiring

Last edited by grafspee; 08-02-2019 at 12:51 PM.
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Old 08-02-2019, 10:26 AM   #147
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Originally Posted by vanir View Post
I might be necrothreading a bit but it's a poorly understood subject so worth stating.
The C3 injector and MW50 boost systems aren't about C3 or MW50 at all, in fact ideally neither would be required for what is being achieved by them.
It's all about over boosting the engine supercharger to accomplish higher than normally rated power outputs. Nothing to do with injecting anything, all about over boosting the blower.

This was a common practise for supercharged aircraft before boost regulators became normally fitted, for example the P40E doesn't have a boost regulator, so the pilot has to carefully manage the throttle below critical altitude or damage the engine with too much boost. This is because the throttle gives maximum boost at critical altitude, air is more dense at lower altitude, so the maximum boost is exceeded below critical altitude unless you have a boost regulator fitted, like a P40M. That one you can shove the throttle to its gate at take off and simply get maximum emergency power, try it in a P40E and you'll hit about 1900hp for half a second and explode the engine. Without a boost regulator you have to watch what you're doing with the throttle under critical altitude, hence it's called critical altitude because you need to be wary under it and not sad altitude because you lose boost above it. That's the way I like to think about it anyway.

Okay so the common practise was to richen the mixture a little too much for normal running and push the throttle a little too far forward, exceeding maximum listed manifold pressure, to exceed normal maximum outputs for a short period, 1-2 minutes tops. But then by midwar pretty much every aircraft had auto mixture and boost regulators so you couldn't do it without a built in override facility or mechanical adjustment, but it probably saved a lot of fighter engines from excited cadets. Simple version is you couldn't do it so easily once a lot of a/c management became automated or semi automated, but it was a common practise when everything was so manual the pilot had to spend more time looking at instruments than they could looking for e/a and broken engines in those days were very common indeed.

An example of this is the RAF operating P40E at 1670hp in North Africa and RAAF actually getting 1720hp from theirs by significantly over boosting using high grade fuels, documented by Allison Engineering in wartime correspondence records. Quite a bump from the 1150hp rated output. It was a letter advising against its continued practise as exceeding manufacturer operating procedure and dangerous for forthcoming engine type production, although Allison was apparently quite pleased their engine stood up better than their expectations in the field.

Adding a charge coolant injector obviously alters this field improvisation of boosted power to one of manufacturer installation under tested guidelines. Initially these did the same thing pilots used to do on their own initiative, ie. a modest boost increase for a very limited duration of 1-2 minutes before holing the pistons. With further development, improvements to the intended engine in chambering and so forth specific to the modification, by 1944 over boosting with a charge coolant got you up to ten minutes of continuous, significant over boost and power increase in hundreds of horsepower, without breaking the engine.

This took time to develop using synthetic fuels, Daimler worked closely with IG Farben to develop combustion chambering throughout the war, their original 1940 goal of 2bar over boost and 1.5bar military power in the forthcoming 605 engine was never actually achieved until the D motor of late44 (and 1.85ata was the best they got on B4). One way of cheating was to hotrod an engine with C3 (or C2) fuel like the 1940 601N motor, Daimlers normally run on B4 so the higher knock rating allowed a limited over boost for 1-2mins. But the BMW 801D already ran on C3 so unless you were going to run it on alcohol you couldn't really hotrod it.

Now the 801D2 was intended from the beginning of production to use MW50/over-boost kits but these weren't available from their manufacturer until February 1944 for whatever reasons. In the meantime Focke Wulf wanted a cheat for the FW190G to give over boost at low altitude for its schnellbomber mission role, which in modern terms you might call deep penetration strike. These were sent in raids against the British coast in 43 and had to outpace Spitfires by the dozen for any chance at survivability. So came the C3 injector, which also tended to find its way into the F series.

German engines use direct injection after the blower compresses raw air, which gets quite hot and throws out the mixture when you over boost. Boost enrichening is normally incorporated into factory tuning but when you over boost you go beyond normal tuning. Not such a big deal in a carb motor like the Merlin, which compresses a fuel-air mixture and can probably get away with manual mixture adjustment to compensate but a real problem in a German engine compressing raw air and then adding pre-calculated fuel metering that didn't have over boost in mind.
The C3 injector just adds an extra fuel injector to the supercharger intake for boost enrichment and it helps a little with charge cooling compared to compressing raw air. The over boost it can withstand is limited but there.

The MW50 is piped to the supercharger exhaust and uses a completely different set of playing rules, the direct injection itself is retuned for over boost enrichment and the injector just cools raw air coming out of the compressor. It allows significant over boost for long periods.

The FW190 radials got MW50 from February 44. The G and F had a much more limited C3 injector over boost before then.
yes british were less caucious in term of boost for example p-51 on 150fuel was set to run 75" and the same plane called MUSTANG IV(british version of p-51) was allowed to run 25lbs boost which translate to 80"
i could not find any data about almost certain engine loss due to use of wep like it is happening in dcs with p-51 this thing i will not understand
i read couple raports of much longer WEP operation then allowed and plane return to base intact any no fatal damage to the engien was done to couse engien seizure
if it was a realy thing army would throw WEP in to trash can

Last edited by grafspee; 08-02-2019 at 10:30 AM.
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Old 08-18-2019, 03:29 PM   #148
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Is it due to my English?

And sorry: I did not mention that MBG is Engine Conrol Unit - a hydromechanical computer allowing to control prop and engine using only one lever.
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Old 08-18-2019, 08:47 PM   #149
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and what the hell is AFR?
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Old 08-19-2019, 07:21 AM   #150
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and what the hell is AFR?
Air Fule Ratio
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