Why was the BF109 so slow compared with the P51?

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Tomo. Would it have been possible to combine 150 octane fuel with MW50 injection and thus create a monster power output?
 
spicmart said:
Tomo. Would it have been possible to combine 150 octane fuel with MW50 injection and thus create a monster power output?
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Of course. P-47D did it in ww2, result was 2800 HP when 150 grade was used together with water/alcohol injection. The post-war US fuel was 145 grade, for example V-1650-9 produced 2200+ HP with water injection.
 
spicmart said:
So the airfoils of a lot of WW2 fighers were obsolete/not competitive at the end? Afaik as the Me 109, Fw 190, F4U Corsair, F6F Hellcat, F7F Tigercat, F8F Bearcat et al are concerned.
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That is a sort of "it depends" answer.
In addition to the basic airfoil shape you needed careful manufacturing to make it work.
The US found for example that the edge of paint from the national insignia on the wing disrupted the airflow to some extent. A lot of people say bug splat will disrupt the airflow.
So you need a proper airfoil, good/excellent manufacturing and good/excellent maintenance in the field to get the benefit. Good airfoil with poor manufacture and maintenance doesn't get you anything while a less than optimal airfoil and good manufacturing and maintenance at least gets you close.
It also depends on what you want it to do, the Mustang's airfoil was less than optimum for carrier operation. Yes they flew of carriers in trials but the handling, stalls, what not what was wanted.
 
tomo pauk said:
Of course. P-47D did it in ww2, result was 2800 HP when 150 grade was used together with water/alcohol injection. The post-war US fuel was 145 grade, for example V-1650-9 produced 2200+ HP with water injection.
Click to expand...


Can you estimate how much power would a 2700 PS Jumo 213J or 2800 PS DB 603N respectively be able to produce with high grade fuel?
 
spicmart said:
Can you estimate how much power would a 2700 PS Jumo 213J or 2800 PS DB 603N respectively be able to produce with high grade fuel?
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Who knows? 1st - I have never heard whether those power figures were attained with B4 or C3 fuel (MW 50 was used in both instances). So we'd probaby see 3200-3300 HP with best fuel around + MW 50.
FWIW, I'll drop the PM to Calum, he is probably the most knowledgable person when it is about German aero engines of ww2 nowadays, to see whether he can share some info here.
 
DB603N = 3200rpm
2800PS @2.1ata manifold pressure using B4+ MW50
3000PS @2.5ata manifold pressure using C3 + MW50

Jumo-213J = 3700rpm
2900PS 2.02ata with MW50 using B4
2400PS 1.66ata no MW using B4

I do not have any reliable documents on 213J with C3. However I would have thought that slightly over 3000PS would have been
perfectly possible from the 213J with C3 and MW50.
 


2900 PS is a very high figure. I have only seen 2700 PS or more often less. The Jumo has greater exhaust thrust so would provide greater propulsion than the DB. Can you say more about it?
 
Am I missing something??

to have greater exhaust thrust you have to have one of two things (or a bit of both) more mass per minute flowing through the engine, that is fuel, air and whatever additives you are using (like water/alcohol or higher pressure exhaust leaving the cylinder. Actually that is not quite right, you need higher pressure (higher velocity) exhaust gas leaving the exhaust outlets/nozzles. But on a V-12 with short nozzles there probably isn't a lot difference unless somebody screwed things up.

If you are getting similar power to the propeller you are probably burning a similar amount of fuel/air in the cylinders (plus whatever it takes to drive the supercharger which is a point of variation, plus whatever it takes in friction to turn the engine over at the specified RPM that is the 2nd point of variation.)

perhaps the Jumo opens it's valves when there is still higher pressure in the cylinders? But once open it is going to drop pretty quick.
 

I don't know much about how much such thrust is generated. Just saw it stated in Manfred Griehl's book about the Fw 190D/Ta 152.
 
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Do you have figures for the Jumo 213S, special low altitude engine? I just once saw a figure in kW but cannot recall it.
 

Can you tell exactly why the 2R1 wing profile was not competitive any more?
 
spicmart said:
Can you tell exactly why the 2R1 wing profile was not competitive any more?
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How many aircraft used it? Other than Messerschmitt (and Bf109 clones), it seems to be approximately no one. This is usually a sign that an airfoil or airfoil family is not competitive or is poorly characterized. This can happen even with modern airfoils, like the Liebeck airfoils, which have a reputation for very poor off-design characteristics and are not widely used.

I've not been able to find much data on the 2R1and 2R2 series, but that may just be because NASA hasn't gotten around to scanning the relevant reports from the NACA (yes, Messerschmitt used NACA airfoils) reports of the 1920s or very early 1930s, when the airfoil was designed.

After digging into Dave Lednicers "The Incomplete Guide to Airfoil Usage" (The Incomplete Guide to Airfoil Usage), I've found these aircraft that used the 2R1 airfoil. The only US aircraft is the Howard DGA. There was a 2R, a 2R1, and a 2R2 series; none were widely used.

  • Root Airfoils
    • 'NACA 2R1 14.2
      • 'Avia CS 199',
      • 'Avia CS 99',
      • 'Avia S 199',
      • 'Avia S 99',
      • 'Hispano HA-1109 Buchan',
      • 'Hispano HA-1110',
      • 'Hispano HA-1112 Buchan',
      • 'Messerschmitt Bf 109B',
      • 'Messerschmitt Bf 109C',
      • 'Messerschmitt Bf 109D Dora',
      • 'Messerschmitt Bf 109E Emil',
      • 'Messerschmitt Bf 109F Fredrich',
      • 'Messerschmitt Bf 109G Gustav',
      • 'Messerschmitt Bf 109K',
      • 'Messerschmitt Me 155B'
  • 'NACA 2R1 16'
    • 'Kawasaki Ki-100',
      • 'Kawasaki Ki-61 Hien',
      • 'Kawasaki Ki-88',
      • 'Messerschmitt Me 209V1
  • 'NACA 2R1 16.5'
    • 'Kawasaki KAL-2'
  • 'NACA 2R1 18.5'
    • 'Messerschmitt Bf 110',
      • 'Messerschmitt Bf 161',
      • 'Messerschmitt Bf 162
  • 'NACA 2R1 19'
    • 'Messerschmitt Me 321 Gigant',
      • 'Messerschmitt Me 323 Gigant' ],
  • 'NACA 2R2 12' => [
    • 'Howard DGA-11',
      • 'Howard DGA-12',
      • 'Howard DGA-15',
      • 'Howard DGA-8',
      • 'Howard DGA-9'
  • Tip Airfoils
  • NACA 2R1 10
    Messerschmitt Me 321 Gigant,
    Messerschmitt Me 323 Gigant

    NACA 2R1 11
    Messerschmitt Bf 109B,
    Messerschmitt Bf 109C,
    Messerschmitt Bf 109D Dora,
    Messerschmitt Bf 109E Emil,
    Messerschmitt Bf 110,
    Messerschmitt Bf 161,
    Messerschmitt Bf 162

    NACA 2R1 11.35
    Avia CS 199,
    Avia CS 99,
    Avia S 199,
    Avia S 99,
    Hispano HA-1109 Buchan,
    Hispano HA-1110,
    Hispano HA-1112 Buchan,
    Messerschmitt Bf 109F Fredrich,
    Messerschmitt Bf 109G Gustav,
    Messerschmitt Bf 109K,
    Messerschmitt Me 155B

    NACA 2R12
    CVV 7 Pinocchio

    NACA 2R2 12
    Howard DGA-11,
    Howard DGA-12,
    Howard DGA-15,
    Howard DGA-8,
    Howard DGA-9
 
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spicmart said:
Can you tell exactly why the 2R1 wing profile was not competitive any more?
Click to expand...

Without going in circumstantial evidence at all, here is how the Germans determined the profile drag coefficient (at lift coefficient of 0.2) of wings of following A/C:
Bf 109: 0.0101
Fw 190: 0.0089
Mustang: 0.0072

(note that Bf 109 have had the thinnest wing of the listed fighters, the Mustang was with thickest - both in % and in centimeters)
The data is noted at "Vee's for victory" book, pg. 338, credited as 'H.H. Arnold Manuscript, Roll 194, Von Karman Report, Library of Congress'.
 
spicmart said:
So the airfoils of a lot of WW2 fighers were obsolete/not competitive at the end? Afaik as the Me 109, Fw 190, F4U Corsair, F6F Hellcat, F7F Tigercat, F8F Bearcat et al are concerned.
Click to expand...

"Obsolete/non competitive" are excessively harsh; airfoil selection is just one factor in an aircraft's overall performance. Many people here seem to overvalue the airfoil, itself, as a determinant of the aircraft's performance (and some people who should know better, such as Riblett, condemn an airfoil for little valid reason). Of course, since the 1970s, all of the airframe manufacturers will use bespoke airfoils, designed with various 3D progams, some of which will even give valid predictions of behavior post-stall and unsteady behavior. Before this time, airfoils were usually picked out of a catalogue, such as Abbot and von Doenhoff's.
 
One wonders what the world record plane Me 209 V1 could have reached with a better airfoil.
Astonishing that the late design Me 155 used the 2R1 while the Me 210/410, a way earlier design, does not.
The Me 155 was developed out of the Me 109 but still they should have made the effort for a better airfoil.



 
Do you have drag coefficients of the Fw 190D, Spitfire and Tempest (and maybe of Russian and Japanese planes)?
 
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