The Best Bf - 109 Variant ?

[Erich]

one reason why the G-6/AS and all AS versions were created..........to stand up with the P-51 escorts. the problem was the P-51's had already gained the altitude as the Luftwaffe was at a disadvantage while climbing to meet the US escorts. It's plain enough through many diaries of first hand accts. The MW 50 could give 10 minutes plus of added power if used in short duration periods. the problem was the pilots didn't do as recommended and shoved their AS engines past the limit, causing peeking and blown pistons.

 

[KraziKanuK]

I did not know that the P-51 could operate at max boost for extended periods of time, RG_Lunatic.

The Merlin in the Spirfire was restricted to 5 minutes at max boost, so what was so different on the P-51 with its Packard Merlin?

 

[Anonymous]

RG:

Erich made good points there.

I never said he didn't.

That point here would rather be the P-51 was not abolutely superior to the Bf109. Better at some things, surpassed doing others.

The only signficant thing the Bf109-G was better at than the P-51 was climbing. In every other relevenant catagory of comparison, the P-51 was superior.

What i mentioned was a fact, the G-10 could outfly the Mustang virtually at any altitude.

Which is simply not true. At high-medium to high speeds, the P-51 out manuvered the G-10 substantially at all altitudes.

The G-6/AS could also more than deal and outfly any enemy pursuer.

Care to explain your thinking here?

The Bf109 could make things the P-51 could not, and viceversa.

Yes, it clould climb very well.

RG: can you mention the weak points of the P-51?
You are not going to suggest it was better at everything, are you?

When compared with the 109G, the only relative weakness is in rate of climb.

Be honest; I can understand the veterans who flew it telling the Mustang is one of the most glorious creations ever and that it was a flawless toy, and that it made an unvaluable contribution to "save humankind from darkness and slavery".

Since you were not there, I do think i can expect a certain level of objectiveness from you.

Finally RG, I have a bit more than 50 gun camera recordings of German fighters pounding the P-51, and from most of them can be concluded the German fighter (either Bf109 or Fw190) could more than outfly the Mustang.[/quote]

Guncam footage almost never tells us much about one plane's relative performance vs. another. Remember, something around 90% of kills scored in WWII the victim never saw the shooter till he was shot down or badly crippled.

=S=

Lunatic

 

[Anonymous]

I did not know that the P-51 could operate at max boost for extended periods of time, RG_Lunatic.

The Merlin in the Spirfire was restricted to 5 minutes at max boost, so what was so different on the P-51 with its Packard Merlin?

5 minutes was the recommended limit of WEP usage. But pilots often maintained WEP power for 15 minutes or even longer. The 5 minutes was a recommended limit, nothing prevented longer usage. A properly operating P-51 at good speed had no overheating problems at any power level. The 109 on the otherhand, would overheat after one to two minutes at high speeds (and not necessarily even at full power).

Also, the Packard Merlin was known to be more robust than the RR Merlin. It was built using superior materials, and production quality was generally higher. This is not a dig at the British, they simply did not have as good of alloys and they were more pressed to maximise production quantities at the cost of a little production quality.

From the Soviet Fighter Tactics manual (1943) - refering to the 109G-2 after study of captured aircraft:

...
Besides, it must be remembered that the Me-109 can only hold the maximum airspeed indicated above for no longer than 1 or 2 minutes in horizontal flight, as their engine overheats and causes the coolant to boil.
...
http://luthier.stormloader.com/SFTacticsI.htm

The problem with the 109 design is that it was never intended to attain those kinds of speeds for sustained periods. The scoops are subject to boundary layer seperation, and later models even had a boundry layer diverter to avoid turblence from this effect. Once the boundary layer lifts (upside-down) away from the lower surface of the wing at the scoop inlet, there is very little effective cooling from the radiators since they aren't getting a steady flow of air.

Late model Spitfires encountered the same issues, but where the Germans chose to accept this condition, believing that only short bursts of speed would be necessary, the British chose to increase the scoop size and injest the seperation as much as possible (even though this was not very efficent in terms of cooling or drag). This issue simply was not discovered until the planes were designed to the point no real solution could be implemented short of a complete redesign.

On the P-51, with its much larger single scoop sitting right below the pilot, the boundary layer seperation problem immeadiately came to the attention of test pilots. They could hear a loud "popping" noise comming from underneath the seat while at high speeds. This was then carefully studied in the full scale and 20 atmosphere wind tunnels at the NACA, and the boundary layer seperation issue was discovered. The solution was to move the scoop inlet away from the wing enough to miss the boundary layer, which is why the P-51 scoop is not flush to the bottom of the plane. So the P-51 had full cooling efficiency until over 500 mph, where the boundary layer got thick enough to start to be partially injested.

=S=

Lunatic

 

[Udet]

RG:

I am certainly not capable of speaking in such a technical style, after all i am not an aviation engineer or technician.

What I have to say is I have a good deal of stuff of info on technical issues of the many versions and sub-versions of the Bf 109 (books, magazines, papers, etc.), and last but not least, the opinions of some men who flew it and of men who flew against it.


This is the first time i read what you say about the over heating problems of the Bf 109 engines.

They over-heated after only 2 minutes at high speeds and, furthermore, not necessarily at full power? What DB engine are you referring to?

Hitherto, i lack arguments to discuss this, but it appears unlikely to me; you are picturing a poor hardly-reliable engine which I do not think was the case of the DB engines, at all.

I will have to ask someone else.

I quite frankly do not care whether if guncamera footage tells little or enough on the performance of an aicraft. What i care about is what i see there, and what do i see?

I recall perhaps one or two shots when the P-51 gets clearly bounced and executed.
In the other hand, I see Mustangs trying to evade and outmanouver German fighters pursuing them for the kill and they did not make it!

RG, i certainly enjoy reading some of your postings, but it appears to me that to an important extent the allied propaganda devoted to defame the Bf 109 played its effect on you.

It is not my intention to change your beliefs or the like, but I am confident since i`ve had access to plentiful info, when i affirm the P-51 was by no means superior to the Bf109.

 

[Anonymous]

Udet,

It was nothing about the engine that caused the problem. The DB engine was excellent. The issue was with the cooling system design.

An airfoil involves what is referred to as the boundary layer. This is a layer of air molecules that are relatively stationary with respect to the wing (or other airfoil surface). Molecules near the wing move with the wing, then as the distance from the wing increases, there are increasing levels of exchange with fast moving ambient air molecules (though this is still relatively small), and then there is a point further from the wing where there is ambient airflow (ie: still air through which the wing is passing). The faster the plane goes (within the subsonic realm - rules change for transonic/supersonic flight) the thicker the boundary layer.

The issue arises when the air flowing across the bottom of the wing encounters the scoop, which creates a back-flow resistance to the air flow. This tends to lift the boundary layer away from the wing and create boundary layer ingestion, which is turbulent air entering the scoop which diminishes cooling efficiency. As speed increases, the problem gets worse, until finally it becomes chronic and the boundary layer lifts up and flows completely over the scoop, creating a vacuum in front of the scoop. It then slaps down to fill the vacuum, then builds up again and repeats the cycle. Air flow into the scoop is non-existent when the flow is over the scoop, and extremely turbulent when it slaps down and does enter the scoop. This greatly diminishes cooling efficiency.

You can visualize what is going on by taking a 2 liter soda bottle, filling it most of the way, and then pouring it out into the sink. Start pouring slowly and the water will flow smoothly out of the bottle. Increase the angle and it flows faster and faster until suddenly it starts "gulping" and the rate of flow is greatly diminished.

In the late 30's they had no experience with this phenomena and so neither the Bf109 nor the Spitfire scoop designs take it into consideration. it came to light on the P-51 purely by accident, because the scoop size and position was such that the test pilots could hear the boundary layer collapsing and making a loud "popping" sound beneath their seats. The solution was to remove the scoop inlet from the wing surface and snorkel it forward:

The 109 had no mechanism to deal with this issue (Bf109G-10):

It was not an issue on the E series, they didn't go fast enough to encounter it except in dives where it was not such a big issue (as power was reduced significantly anyway). It started to become a slight issue on the F series, and it was a significant issue on the G series but was never dealt with, probably because there really is no good solution for wing scoops.

The British simply increased the scoop height to ingest the boundary layer at higher speeds, accepting the added drag this created at all speeds:

Spitfire Mk. I (only has 1 scoop)

Spitfire Mk. IX

Spitfire Mk. XIX

So it's nothing to do with the quality of the engine, it has to do with the cooling system design. At high speeds the cooling system simply gets bypassed by the boundary layer separation effect. The Bf109G/K has no remedy for this issue.

As for pilot comments, P-51 pilots consistently claim they could easily out-turn 109's at speed, and FW's too but less easily. Pilot plane bias has to be considered as well of course. But kill stats really are meaningless because the great majority of the time the victim never saw the plane that shot him down or did not see it until it was too late. This does not always mean a "bounce" of an unaware target (though often it does), it can also mean they were engaging an opponent (either offensively or defensively) when another opponent they were unaware of shot them down.

By 1944 the Bf109 was long in the tooth. Its design had never considered 400 mph class level speeds, and its cooling system was not made for such speeds. With the cooling system barely functional, the radiators overheated rather quickly.

BTW: the Soviet Fighter Tactics book did not become available to anyone but Soviet military personnel until after the fall of the Soviet Union in the 1990's. It was created to teach Soviet pilots how to fight the German planes in late 1943 and was based upon both combat experience and testing of captured aircraft. This was not "propaganda" to defame the 109.

In general, it appears the Germans considred 2 minutes at high speed enough for combat needs. The FW190A series was limited to about 3 minutes of top speed performance by design. The very skilled pilots of the Luftwaffe' were probably able to make this work for them most of the time.

=S=

Lunatic

 

[KraziKanuK]

I don't know where you get your info from but the 190 could do 10 minutes on 'boost juice' (C3 injection or MW50). The 109 as well. The 109F and on had a boundary seperater inside the radiator duct.

Pilot anecdotes say time was increased in the FW-190A8 and later series begining in mid 1944 to 20, 30, and finally 40 minutes at 1.42.

 

[Anonymous]

I don't know where you get your info from but the 190 could do 10 minutes on 'boost juice' (C3 injection or MW50). The 109 as well. The 109F and on had a boundary seperater inside the radiator duct.

Pilot anecdotes say time was increased in the FW-190A8 and later series begining in mid 1944 to 20, 30, and finally 40 minutes at 1.42.

Yes... in a climb. It was not power output that was the issue, it was speed. All the German WEP and SEP systems were quite useable for extended periods at the lower speeds utilized while climbing, typically about 180 mph, where the cooling system was at peak efficeincy. This had no relevance to the ability to maintain top speed in level flight.

A boundary layer seperator inside the duct helps with boundary layer issues within the scoop and helps to settle the aiflow down and improve cooling. This helped deal with the issue at medium speeds. It does nothing about boundary layer issues outside the scoop which occur at top speeds.

=S=

Lunatic

 

[DerAdlerIstGelandet]

Well well, hey everyone, how are you all. I have returned from Iraq and am back home now.

I agree with both of you on most of your points.

First of all even Luftaffe pilots would tell you that the Me-109's ability decayed as it was developed. Yes the K model was faster and such not, but it lacked in maneavueraibliy (sorry I know my spelling is terrible, me and my wife have been drinking wine, and she is taking a nap, so I get to get ont he internet).

RG you are correct the F model was the finest version when based one the allied counterparts, it was fast and very maneverourable for its time. I personally like the G better, but that is stricktly opinion.

As for the ability to sustain top speed there were several aircraft that the Luftwaffe had that could contain these speed but they were put into full produciton before the war was over: Me-155B, Me-109H, Ta-152H:

Focke Wulf were successful with the Ta-152 and in the H version were finally in position to provide the Luftwaffe with its long awaited high alltitude fighter. But the Aircraft which was supiorior to all Allied machines at alltitudes aber 10,000m (33,000ft), was built in only small numbers, and did not see service in its inteded role.

The design had scope for a great deal more technical development and the design was still far from the end of its potential.

Max Speed: 740km/h at 12000m/459mp/h at 39500ft
Max Range: 1290km at 10500m/ 801 miles at 34500ft

Luftwaffe Secret Projects Fighters 1939-1945 by Walter Schick and Ingolf Meyer

 

[Erich]

good to see you back. How long are you in the states for ?

 

[Erich]

oooooooooooooops should have said Germany not the states. Have a glass of wein on me man.

Erich ♪

 

[DerAdlerIstGelandet]

Thank you my friend. Yes I am back in Germany right now. I wlll drink a good White Merlot for you my friend and tomorrow I will drink a good Weizen Bier for you!

 

[Erich]

enjoy, I think I will have to go downtown and pick up a Heffeweizen afer work.....kick my feet up and type away on the forum here...

E ~

 

[cheddar cheese]

Glad to see youre back safe Adler - a fair bits happened while you were away.

 

[the lancaster kicks ass]

i'd be very gratefull if someone could send me a crate of beer, just label it "plane models" or the folks could get bit suspicious.............

 

[Anonymous]

one reason why the G-6/AS and all AS versions were created..........to stand up with the P-51 escorts. the problem was the P-51's had already gained the altitude as the Luftwaffe was at a disadvantage while climbing to meet the US escorts. It's plain enough through many diaries of first hand accts. The MW 50 could give 10 minutes plus of added power if used in short duration periods. the problem was the pilots didn't do as recommended and shoved their AS engines past the limit, causing peeking and blown pistons.

MW50 could certainly be used for 10 minutes or even more. But not for speed. This was used to support fast climbs, usually at about 180 mph where the cooling system is at peak efficeincy. So there is no conflict here Erich.

 

[DerAdlerIstGelandet]

Well thats good to know!

 

[Erich]

The boost through the two stage supercharger besides climbing was used for short bursts of speeds according to the pilots, Horst Petzschler for one in May of 44 while with 2./JG 3 vs P-51's at high altitude.

also in our forth coming book the night pilots in their Bf 109G-6/AS's used it to dive and catch up with the LSNF mossies on their way to Berlin or flying away from the city during the fall of 44. Even in the dive and flat out to catch the wooden a/c they would push the AS craft to the limit and blow out the pistons.............Georg Czypionka, Fritz Neppasch, Kurt Welter, etc.

E, glad we are back on !

 

[Udet]

RG_Lunatic:

I did print all the technical speech you delivered here and had it sent to someone who knows a hell of a lot about engines, cooling systems and boost gear of ww2 aircraft. So far, i can say i rest my case.

I do not doubt you know a good deal on technical stuff, but since you have a conflict of interest here, you might be giving away only the information that serves such interest.

I am also looking forward to have some of my Luftwaffe guncamera shots made into donwloadable MPEGs, so you can see many many P-51s getting vivisected (the pilots included) by German interceptors.

My question is: have you ever seen footage showing Mustangs getting chewed by German interceptors?

I´ve met guys from the USA who had seen none, until i showed them a few scenes. Shocked is a moderate term to describe the look on their faces when they saw the images.

Seeing a P-51 getting pulverized, to smithereens, catching a one second glimpse of the body of the pilot all twisted between the large parts of the fuselage, debris, sparks and smoke of his plane, can really sicken you (just like it made feel sick).

 

[kiwimac]

IMO, F-series

Kiwimac