Bf 109 G-10 vs K-4

[alejandro_]

I have put together some graphs comparing the maximum speed and climb performance of Bf 109 G-10 with other German and Allied types from the same era. I would like to thank CORSNING for compiling a huge amount of performance data. Graphs titles and axis are in Spanish, but should be easy to understand.

 

[drgondog]

Question - When did LW approve 1.42 ata for combat ops?

 

[alejandro_]

It depends on the 109 version. According to the information I have the 1.42ata was cleared for the Bf 109 F-4 at the turnover of 1941/42.
For the G version, apparently it was cleared after August 1943, but there are no tests at this setting. Power output:

Rating----DB 601E (@4800m)----DB 605A (@5700m)
1.30ata---1200hp---------------1260hp
1.42ata---1325hp---------------1355hp

 

[tomo pauk]

Thank you for the graphs. BTW - removal of the ban also meant that max RPM was now 2700 for the DB-601E and 2800 for the DB-605A. That, combined with increased boost, gave the increase in power at all altitudes.

 

[dedalos]

i feel that by 1945 the weak part of the combination Bf109K4/DB605D was the airframe. On 1850/2000 ps would be reasonable to expect better performance .Considering that the K4 had a clean fuselage and fully covered landing gear, could we conclude that it was the obsolete wing profile that crippled the aircraft s performance? I feel that a Fiat G55 or a Ki84 with DB605D would be much superior in comparison with the Bf109K4.

 

[tomo pauk]

The DB 605D at 1800 PS provided about as much power at all altitudes as the Merlin 63 or the V-1650-7 at 130 grade fuel, while at 150 grade fuel those Merlins were comparable to the DB 605D running on C3+MW50, ie with 2000 PS. The 109K-4 was making 441 mph at 24600 ft, using 1540 HP (1565 PS) compares well with Spitfire IX (Merlin 63, 408 mph at 25000 ft), and even the P-51D with 442 mph at 26000 ft is in the ballpark. German A/C is much smaller than the Anglo-American compatition. The K-4 should climb better than the much heavier P-51D.
Limitations of the airframe were in other categories - Western fighters, G.55, Re.2005 and Fw 190 (and Hayate), being bigger, were better capable to carry ever increasing fuel, weapon and ammo load, plus ever increasing amount of external fuel all in the same time. The lumps from the HMGs were still there, if more streamlined, and we also have the bumps at the wing due to the bigger wheels used now.
The rate of roll of the 109 at high speeds being low, and cockpit canopy never going to the bubble canopy type. Western designers also went to much re-designed or whole new fighter designs much more frequently than the 109 ever got, ie. Spitfire's new wing + Spiteful; Typhoon -> Tempest -> (Sea) Fury; Mustang -> lightweight Mustang, P-47D -> P-47N, while the Fw 190 finally got V12 engines, improved/changed wing plus whole plethora of improvements to restore it's place among the top fighters.

So yes - the G.55 or, say, Fw 190 with DB-605AS(M) and 605D would've make sense, even though the 'G.55-AS' or 'G.55-D' would not be as fast as the 109G-10 or the K-4. More importantly, it would've been slower than the P-51D. The MC.205-AS on the other hand...

 

[Juha2]

also 109 E was a major redesign and after that Bf 109 got a new wing, nose and tail with 109 F. And a new higher fin and rudder because of high speed handling difficulties from later Gs onward.
Juha

 

[tomo pauk]

IMO the Emil was a slight redesign, aimed to have a big 1000+ HP engine installed. It got the new radiators and increased fuel tank vs. the Jumo 109s. The wing of the 109F was new, but it still used the legacy profile, it didn't add any lift capability to the airframe nor it offered 'proper' undercarriage; rate of roll barely improved. The aerodynamics indeed improved due to changes to the nose, radiators and rear part of the A/C.

 

[GregP]

The late-model Bf 109s shared a lot of deficiencies, as noted above. Windscreen and canopy design, landing gear, higher-drag radiators compared with competition, higher-drag oil coolers, too. The bumps and scoops didn't help much, either. A big scoop sticking out has more drag than an integrated scoop, if it is designed right.

I think the roll could have been fixed. We did and Germans were as inventive as anyone, including us. They just didn't. Ditto the lack of pilot-adjustable trims except stabilator. The could have fixed the landing gear, too.

The fact remains that the Bf 109 stayed at or near the bottom for number of man-hours required to build it and get it into service. That may well be the main reason these things weren't fixed ... because Germany had a limited amount of labor to use (especially versus the USA), and they needed planes pretty quickly. I wouldn't be surprised to find out that manufacturing time was a major player in what got fixed in German airplanes.

Now if only they had trained pilots somewhat quicker ...

And, before anyone says differently, the Bf 109, in the hands of a good pilot, was dangerous until well after WWII was over, in ANY variant flying at the time. It was never "meat on the table" unless you, as a veteran, found a totally green pilot in a 109, who was doing what green pilots do instead of paying attention.

 

[BiffF15]

Green or not, a kill is a kill.

Cheers,
Biff

PS I agree you have to honor the threat regardless!

 

[alejandro_]

These two excerpts come from the book Nest of Eagles: Messerschmitt Production and Flight-testing at Regensburg 1936-1945, by P. Schmoll. I would definitely recommend it to those interested in German aviation.

A further modification to increase the performance of the bf 109 was the installation of MW-50 (a 50/50 volume ratio of methanol/water injection) in the aircraft, with which a short-duration engine emergency power could be achieved and which was built in gradual stages into the Bf 109 G. Peter Duttmann, a pilot with II./JG 52, still possesses at the time of writing a datasheet for the DB 605 D, which with the MW-50 injection, could produce 2,200 hp. He related to the author "With the auxiliary MW-50 installation in my Bf 109 G-10 in which I flew till the end of the war, I was able to save myself in all of the prickliest situations, of which there were several in April 1945. When no methanol was at hand, we used distilled water which functioned just as well, except that we were no able to fly high, otherwise the whole installation froze. In the sorties we flew short before the end of the war in low-level flight in the Cham area and east of Regensburg, we often met US fighters, and although they were superior to us in numerical terms, we were able to get away from them. The fastest Bf 109 I ever flew in, I handed I handed over to the Americans on 8 May 1945 in Neubiberg"

Arno Fischer of I./JG 53 recalled of the MW-50: "At the beginning of 1945 we received the Bf 109 G-10 with MW-50. In my first sortie with the Bf 109 G-10 on 27 January 1945, I was in an air battle with 20 Yak 9s – four German fighters versus 20 Russians. For almost 20 minutes, we fought a turbulent air battle over StuhlweiBenburg in which much shooting took place, but nothing was hit by either opponent. During the course of this engagement, I used my MW-50 for brief periods many times. The engine turned at higher revs and made such a noise that it made me believe it would explode at any moment. In fact, it transpired that by longer use of emergency power, the base of the pistons burned through. I used the ME-50 most unwillingly since, as I said, the engine was being taxed to its limits and made a peculiar sound which did not sound very reassuring. In dangerous air combat situations, however, you had a short-duration power increase available to you abd could raise your speed near the ground to a good 600 km/h (373mph)".

Nest of Eagles: Messerschmitt Production and Flight-testing at Regensburg 1936-1945, de P. Schmoll, Classic Publications (2010).

 

[dedalos]

These two excerpts come from the book Nest of Eagles: Messerschmitt Production and Flight-testing at Regensburg 1936-1945, by P. Schmoll. I would definitely recommend it to those interested in German aviation.

A further modification to increase the performance of the bf 109 was the installation of MW-50 (a 50/50 volume ratio of methanol/water injection) in the aircraft, with which a short-duration engine emergency power could be achieved and which was built in gradual stages into the Bf 109 G. Peter Duttmann, a pilot with II./JG 52, still possesses at the time of writing a datasheet for the DB 605 D, which with the MW-50 injection, could produce 2,200 hp. He related to the author "With the auxiliary MW-50 installation in my Bf 109 G-10 in which I flew till the end of the war, I was able to save myself in all of the prickliest situations, of which there were several in April 1945. When no methanol was at hand, we used distilled water which functioned just as well, except that we were no able to fly high, otherwise the whole installation froze. In the sorties we flew short before the end of the war in low-level flight in the Cham area and east of Regensburg, we often met US fighters, and although they were superior to us in numerical terms, we were able to get away from them. The fastest Bf 109 I ever flew in, I handed I handed over to the Americans on 8 May 1945 in Neubiberg"

Arno Fischer of I./JG 53 recalled of the MW-50: "At the beginning of 1945 we received the Bf 109 G-10 with MW-50. In my first sortie with the Bf 109 G-10 on 27 January 1945, I was in an air battle with 20 Yak 9s – four German fighters versus 20 Russians. For almost 20 minutes, we fought a turbulent air battle over StuhlweiBenburg in which much shooting took place, but nothing was hit by either opponent. During the course of this engagement, I used my MW-50 for brief periods many times. The engine turned at higher revs and made such a noise that it made me believe it would explode at any moment. In fact, it transpired that by longer use of emergency power, the base of the pistons burned through. I used the ME-50 most unwillingly since, as I said, the engine was being taxed to its limits and made a peculiar sound which did not sound very reassuring. In dangerous air combat situations, however, you had a short-duration power increase available to you abd could raise your speed near the ground to a good 600 km/h (373mph)".

Nest of Eagles: Messerschmitt Production and Flight-testing at Regensburg 1936-1945, de P. Schmoll, Classic Publications (2010).

Very interesting post. I would like to make some comments
1) It appears that experienced pilots could defend themselves flying the G10 and K4 versions even at the very last days of the war and against impossible odds despite the fact that the aircraft was obsolete
2) It is noteworthy how late, the main eastern front units received MW 50 equiped Bf 109s.
3) It s interesting the comment that they could get away from us fighters at low level as late as April 1945. As far as i know ,the us fighters with their 150 octane fuel should have a massive speed advantage.
4) It appears that even the DB605D, with its improved block and oil circulation system was hard pressed by the use of MW 50. I wonder what was the ability of the earlierDB605AM & ASM to handle such loads.
5) 2200ps out of the DB605D would require 2,3 ata boost. On theory possible,especially if special alloys were available, but even the1,98 ata use is doubtful. A 109 with such boost would have a decent power to weight ratio

 

[tomo pauk]

...
5) 2200ps out of the DB605D would require 2,3 ata boost. On theory possible,especially if special alloys were available, but even the1,98 ata use is doubtful. A 109 with such boost would have a decent power to weight ratio

The Soviets reduced the compression ratio of the AM-42 engine down to 5.5:1, so it was making 2 ata boost despite just 95 oct fuel. The V-1710, with CR of 6.65:1 was making some 2.5 ata with 130 grade fuel and water injection. The Jumo 213A - CR of 6.5:1, boost, 2 ata on B4 and MW 50. V-1650-9, with CR of 6:1, 3 ata on 145 grade + water injection.
Jumo 213E - 6.5:1, has intecooler, made 2 ata on B4 + MW 50.
So - reduce the CR to under 6.5:1, install intecooler, and both boost and power will improve considerably.

added: *for the DB 605s - install the swirl throttle (before the S/C) instead of the butterfly throttle, early enough. Will add another 150-200 HP at low level, the gain decreasing to zero at rated altitude. Jumo 213 got it, idea was taken from the Mikulin's engines.*

Bf 109 have had excellent power to weight ratio, as-is.

 

[alejandro_]

Glad that it was helpful

3) It s interesting the comment that they could get away from us fighters at low level as late as April 1945. As far as i know ,the us fighters with their 150 octane fuel should have a massive speed advantage.

I tend to take these accounts with a grain of salt, as the exact circumstances were not known. By April 1945 most pilots were probably interested in making it home alive and not prone to risks. Also, they could be running out of fuel.

In any case the K-4/G-10 was a pretty fast aircraft at low altitudes, and quite small too.

5) 2200ps out of the DB605D would require 2,3 ata boost. On theory possible,especially if special alloys were available, but even the1,98 ata use is doubtful. A 109 with such boost would have a decent power to weight ratio

I thought about this, but maybe it was an error or typo? There is a lot of documentation with the 2,000 PS @1.98 ata setting.

 

[tomo pauk]

Another thing that might've increased the power down low for the DB engines is switch from variable-speed S/C to the, say, 3-speed S/C - cancels losses due to slippage in the hydraulic coupling. For the Fw 190 installation - make a turbo DB engine with properly streamlined installation, or make a turbo-compound installation. Granted, historically, the latest is a bit beyond the ww2 time line.

 

[GregP]

Hi Dedalos,

Your point #3 is interesting. The Bf 109 using MW50 is similar to a U.S. fighter at WER. Since the war was winding down, I am thinking that nobody wanted to be the last prisoner taken, and they likely would not use WER to catch a Bf 109 unless they were green rookies. The Allied pilots were flying over what was still hostile territory, and probably didn't take any chances they didn't need to take. Indiscriminate use of WER over Germany could spell engine issues for a U.S. fighter just as MW50 sounded bad to the German pilot.

I took some flak some years back for saying it, but top speed is for test pilots. Real combat pilots don't fight there except maybe in a descending fight from altitude. Nobody would regularly go to WER just because combat was closed. WER was for escaping, saving your life when you were about to be shot down, or something similar, not for catching up to an enemy running away when there are a thousand other fighters around ready t pounce on him.

None of the above says the Bf 109 wasn't a dangerous opponent late in the war, it was, especially if competently flown.

 

[dedalos]

Another thing that might've increased the power down low for the DB engines is switch from variable-speed S/C to the, say, 3-speed S/C - cancels losses due to slippage in the hydraulic coupling. For the Fw 190 installation - make a turbo DB engine with properly streamlined installation, or make a turbo-compound installation. Granted, historically, the latest is a bit beyond the ww2 time line.

I thought that feature provided the DB with a better power curve.And reducing the CR would further decrease the range of action. I would think an annular radiator(possibly with an inter cooler too), like the Fw 190D. It would provide better aerodynamic configuration for the 109 , plus better cooling efficiency. Thus perhaps the engine could be pushed harder. But without proper alloys to withstand the additional loads no fuel advances, or improved radiator, could have an effect. I wonder if would be possible with the technology of the era to use changing valve timing or 5 valves per cylinder in order to improve the specific output of the engine

 

[Shortround6]

the drop in range wouldn't really be that much. A few minutes out of an hour? If you could even measure it? We are not talking transatlantic flights here.
Change from 7.5 to 6.0 might be worth 5%.
The 109 used a decent radiator, not as good as some, better than others. However going from 1400-1500hp to 2000hp certainly requires a bigger radiator, especially if you are going to use the extra power for more than a few seconds at a time.

Even if you could change the valve gear, do you really want to? More complexity, more weight, new tooling.
The DB 605 already used a pretty good amount of valve overlap compared to other WW II engines.
Aircraft engines also operated over a pretty restricted rpm range. most covered a range of 4-5 times to full throttle compared to idle, and only about 2 to 1 from cruise speed to full throttle. Nothing like car engines let alone racing engines.

 

[tomo pauk]

I thought that feature provided the DB with a better power curve.And reducing the CR would further decrease the range of action. I would think an annular radiator(possibly with an inter cooler too), like the Fw 190D. It would provide better aerodynamic configuration for the 109 , plus better cooling efficiency. Thus perhaps the engine could be pushed harder. But without proper alloys to withstand the additional loads no fuel advances, or improved radiator, could have an effect. I wonder if would be possible with the technology of the era to use changing valve timing or 5 valves per cylinder in order to improve the specific output of the engine

The variable-speed drive was certainly better than 1-speed drive, and everyone uses 87 oct fuel and no ADI. However, no-one used 1-speed drive on their major military engines that late in the war except Soviets and British on some low-alt engines, and better fuel and ADI is videly used. Against a 2-speed drive, both choices have advantages - the variable-speed drive will make better power between the two power 'peaks', but a 2-speed drive will make much better power at low level (since there is no losses at hydraulic coupling), exactly where the engine was capable to develop the best power. See, for example 1-stage Griffon and BMW 801D vs. DB 603A.
The 3-speed drive can smooth the power curve further, and it can provide even better power down low vs. a 2-speed drive, let alone vs. variable speed.
I've also sugested the use of swirl throttle instead of the butterfly throttle, as it was done on the Jumo 213 engines. Nice thing about that throttle is that it does not increase the IHP (=BHP + losses) nor engine temperature and stress, while increasing BHP (= power available for the prop). That is avilable, admitedly, just under the rated altitude(s).
The BF 109G got a oil cooler some time in 1944 historically. As for the new raditor layout - perhaps in front of the wings like the Mosquito - will not be so tricky for the CoG like the annular layout? I'd certaily try to go with fuselage-connected engine cowl rather than with engine-connected cowl, in order to shave some drag.

 

[dedalos]

The variable-speed drive was certainly better than 1-speed drive, and everyone uses 87 oct fuel and no ADI. However, no-one used 1-speed drive on their major military engines that late in the war except Soviets and British on some low-alt engines, and better fuel and ADI is videly used. Against a 2-speed drive, both choices have advantages - the variable-speed drive will make better power between the two power 'peaks', but a 2-speed drive will make much better power at low level (since there is no losses at hydraulic coupling), exactly where the engine was capable to develop the best power. See, for example 1-stage Griffon and BMW 801D vs. DB 603A.
The 3-speed drive can smooth the power curve further, and it can provide even better power down low vs. a 2-speed drive, let alone vs. variable speed.
I've also sugested the use of swirl throttle instead of the butterfly throttle, as it was done on the Jumo 213 engines. Nice thing about that throttle is that it does not increase the IHP (=BHP + losses) nor engine temperature and stress, while increasing BHP (= power available for the prop). That is avilable, admitedly, just under the rated altitude(s).
The BF 109G got a oil cooler some time in 1944 historically. As for the new raditor layout - perhaps in front of the wings like the Mosquito - will not be so tricky for the CoG like the annular layout? I'd certaily try to go with fuselage-connected engine cowl rather than with engine-connected cowl, in order to shave some drag.

Interesting your comment about the variable speed drive. But , the americans did introduce a similar system on the F4U5. Why would introduce it if it was inferior than the 3 speed supercharger?
I believe you have an entire thread about the swirl throttle. Could you send me a link?
I believe that leading edge radiators was out of the question, mainly for production reasons. The annular radiator certainly would require some CoG measures,but i believe it was possible through relocation of equipment in the rear fuselage Even better would be the removal of the the Mg 131s and their heavy synchronization gear from the nose of the aircraft and replace them with wing belt fed MGFF/M . The japanese did introduce belt fed mechanisms for their type 99 cannons and i believe german experimented too.