I need help

Discussion in 'Flight Test Data' started by Mitya, Jun 7, 2008.

  1. Mitya

    Mitya Member

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    Comrades, moderators, I do not know as to name a theme, therefore, if you will consider the name not true rename it, please.
    So, we shall start.
    I am interested very much with the data on Bf-109G2 and Bf-109G4. In what difference G2 from G4? In the book " Bf-109G in action." it is spoken that G4 has wider tire covers and other radio station. And what characteristics G2 and G4?
    If I have correctly understood, G2=G4 under characteristics?
    "Messerschmitt Bf 109G-3 Identical to the Bf 109G-2 version, except the radio equipement. The Bf 109G-2 was fitted with a FuG 7a radio, where the Bf 109G-3 was fitted with a FuG 16z radio. Messerschmitt Bf 109G-4 This version was produced parallel with the Bf 109G-3. The only difference was the lack of presurisation of the cockpit. This version could also be used as a reconnaissance aircraft. For this the 20 mm MG 151/20 cannon would be removed, and a single vertical camera be installed in the rear fuselage."
    ImageShack - Hosting :: 23019211bs4.jpg
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    I today on work have seen all forum, but that have not found, that me interests...
    I have gone here: WWII Aircraft Performance
    And, that I there have seen: "Description of the basic model Me 109 G 1" "Aircraft Model Bf 109 G-1
    with DB 605 A engine" on: Me 109 G Flight Tests. So differ?
    At one 21m/s, and at another 17,4 m/s at the ground. Why such big difference? This is Bf-109G1... That do I do not understand? This is one fighter, And the data so differ...
    Here: Spitfire Mk IX versus Me 109 G - Flight Testing in general figures not such! Why? Climb not that, speed not that...
    Now I fasten the report of scientific research Soviet institute of the Air Forces (НИИ ВВС). Look as strongly differs G2 from G4. Though everywhere it is written, that G2=G4, G1=G3. But why such results? Why G2 in Soviet Union has given out the best characteristics, than at Germans? If to look under the reference is higher. Can what tested our him at pressurization 1,42 ata? I have in view of G2. On G4 I do not know in general that...
    Who can can result all characteristics G2 and G4 is direct here? Very much it is necessary...
    G4 it is much heavier, than G2. Figures it is not known whence... Under the report of scientific research institute of the Air Forces (I do not have data on G4 more!) a difference only 4 kg!
    Who can can result all characteristics G2 and G4 is direct here? Very much it is necessary...
    Here:Ñðàâíåíèå èñòðåáèòåëåé Âòîðîé ìèðîâîé âîéíû G4 it is much heavier, than G2. Figures it is not known whence... Under the report of scientific research institute of the Air Forces (I do not have data on G4 more!) a difference only 4 kg!
    And a difference in speeds and it is especial in climb simply huge!
    Somebody as the ready table could not give characteristic G4 in comparison with G2? Somebody also could not comment on it: Why G4 and G2 here have capacity 1550 h.p.? Unless DB-605A had such capacity in the spring 1943?
    Whether could be such, what in Soviet Union G4 tested with the limited pressurization? Namely 1,3 ата (2600 rev/min). G2 it was tested in the winter 1943 at 1,42. Such difference can because of it?
     

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  2. syscom3

    syscom3 Pacific Historian

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    Hi Mitya.

    Where in Russia are you from?
     
  3. ponsford

    ponsford Member

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    I don’t know about G-2 and G-4 specifically, but check the critical altitudes (horizontal flight) from these various BF 109 Gs flight tests from your link.

    6.4 km (note the desired value was 7.0 km)
    Me 109 G-1 Flight Test

    6.1 km Me 109 G-1 Flight Test

    6.6 km Me 109 G-6 Flight Test

    6.6 km Me 109 G 1

    6.6 km Me 109 G-5 Flight Test

    6.4 km Me 109 G-1 Kennblatt

    6.7 km http://www.wwiiaircraftperformance.org/me109/db109g.pdf

    6.2 / 6.5 km http://www.wwiiaircraftperformance.org/me109/frm1l43-190-109.pdf

    Scattered at something less than 7 km? But calculated 7 km? http://www.wwiiaircraftperformance.org/me109/erla109g.pdf

    6.4 km http://www.wwiiaircraftperformance.org/me109/me-109g2-finn.pdf

    6.5 km http://www.wwiiaircraftperformance.org/me109/glce2-109g6.jpg

    6.5 km http://www.wwiiaircraftperformance.org/me109/me109g6-combat-emergency.jpg

    Compare these German figures against the 7000 m found at your link Ñðàâíåíèå èñòðåáèòåëåé Âòîðîé ìèðîâîé âîéíû (and also some of your attached images)

    Curiously critical altitudes vary in that table between the Bf 109 G-2 (7000 m), G-4 (7000 m) and G-6 (6600 m)

    Hope that helps. I didn't look at climb differences but it probably also has something to do with critical altitude and configuration differences such as wing guns, etc.
     
  4. KrazyKraut

    KrazyKraut Banned

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    G-3 also had some alterations to the landing gear, that were introduced on late G-2 versions (only late ones, not all). This included new broader landing gear tires and the subsequent blisters on the wings and a larger and fixed tail wheel. This might be where weight and performance differences come from.
     
  5. Mitya

    Mitya Member

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    We look 2 pages from the report. It is visible, that G4 weighs all on 4 kg more, has too armament (1 MG151/20, 2 MG17), has precisely same power on a rating, and a variance in velocities and it is especial in climb it is very essential. In fact not 5 km/h, not 10 km/h, and in 16 km/h near the ground, but it still that. Climb G4 it is worse, than at G2 almost on 3 m/s!!! Why? It is admissible, that G4 had power 1310 h.p., and G2 1475 h.p. Can what G2 he had "superfluous" 165 h.p. had climb on 3 m/s more? There are test datas of the production G2 and G4?
    Here: Me 109 G-1 Flight Test is not present that about the production G2 and G4. Where they can be found?
     
  6. Mitya

    Mitya Member

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    Superfluous 4 kg are capable to result in loss climb on 3 m/s?
     
  7. Mitya

    Mitya Member

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    Why (From here: Me 109 G Flight Tests)???
    [​IMG]
    [​IMG]
     
  8. KrazyKraut

    KrazyKraut Banned

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    I think the induced drag is more important here than the added weight. According to Kurfuersts page the extended tailwheel ("ausgefahrener Sporn") results in loss of 12 km/h of top speed! So -3 m/s climb don't sound too unreasonable.

    Kurfrst - Leistungzusammenstellung Me 109 G.
     
  9. Mitya

    Mitya Member

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    12 km/h 3 m/s!!! Really inductive resistance of a wheel is so great, that 1 km/s, and the whole 3 will be lost not!!! As far as I understand climb depends on capacity of the motor and specific loading kg / h.p., and aerodynamics will already depart on the second plan (in this case). G2=0,430 kg/h.p. G4=0,430 kg/h.p. I.e. on on this important parameter too equality... In fact G2 it is practically identical with G4. And a difference in climb 3 m/s! Why?
     
  10. kool kitty89

    kool kitty89 Well-Known Member

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    Drag will have some effect on climb as well (moreso if a plane's optimum climbing speed is high -much moreso for jets-)
    And increase in parasitic drag from the wheel at high speed would be a much higher contributor than the added induced drag.

    For sustained turns and climb, the optimum speeds tend to be in the lower end of the speed range, where induced drag (and weight) is much more significant.

    But while the 13 km/h (8 mph) speed loss sounds reasonable, I agree a 3 m/s climb does not. -that's 590 ft/min loss!-

    Even a loss of 1 m/s seems somewhat high, nearly 200 ft/min.
     
  11. delcyros

    delcyros Well-Known Member

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    Bf-109G1 + Bf-109G3:

    HIGH ALTITUDE FIGHTERS.

    Equipped with cockpit pressurization and provisions for GM-1 injection.

    Bf-109G2 + Bf-109G4:

    MEDIUM ALTITUDE FIGHTERS

    No cockpit pressurization and therefore a bit lighter.

    The G-4 submodel does have a larger main wheel (special requirement from improvised field landing sites) and in detail some different cooling capacity.

    -at least as far as I do understand. I am sure that Kurfürst can shed more light on this.

    best regards,
     
  12. claidemore

    claidemore Member

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    Check out this page on Kurfurst site:
    Kurfrst - Flugleistungen Me 109G - Baureihen

    Clean G2 and G4 are missing, but compare weights of either plane with similar loadouts, for instance 4 x 50kg bombs, or Mg151 gondolas. You get a difference in weight of 80 or 60 kg respectively. (don't know why there is a 20kg discrepancy there).

    So weight difference is not 4 kg, it's at least 60 kg.

    Also, they had to put bulges on the wings of the G4 to fit the bigger wheels? ie more drag?

    The two big differences would be weight (60kg) and more drag from the bulges on the wings.
     
  13. Mitya

    Mitya Member

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    Look at those figures which I have resulted above: G2=3023 kg, G4=3027 kg. A difference in 4 kg, instead of in 60 kg. We look further. Arms both at G2, and at G4 1 МГ151/20 and 2 МГ17.
    I see here: Kurfrst - Flugleistungen Me 109G - Baureihen , what: "The official performance specifications for the G-1 (which applies to the very similiar G-2, G-3 and G-4) at Steig- und Kampfleistung was noted as 537 kph at SL, and 660 kph at 7000m."
    As I understand the data for G1=G2=G3=G4. Whether or not? Distinction in speed can be caused by that at G4 were small bulbes on a wing. Probably on tests the wheel was not removed a tail wheel. On G2 it was removed. As we see at the big heights where the density of air is less, G4 is almost equal on speed G2. But climb... Climb very, very bad at all altitude...
     
  14. Mitya

    Mitya Member

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    Difference only in wider tire covers and radio station. The glider and the motor are identical. Power of the motor on idea too (or no?). But the difference in climb is simply huge!
    Now we compare G4 with G2. ;)
     

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  15. delcyros

    delcyros Well-Known Member

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    The point of departure in Your understanding of the performances from mine appears to be that the G-1/G-3 cannot be compared with the G-2/G-4. You may compare G-1 with G3 (one pairing!) and G-2 with G-4 (another pairing) but not interchange between them. The performance of the Bf-109G-1 and G-3 at optimum altitude (with "Sondernotleistung"/GM-1 injection) is significantly higher than those of the G-2 and G-4 respectively. Esspeccially because the critical altitude with GM-1 injection will be somehow larger. Same power and drag but a larger critical altitude will translate to increased top speed and climb. This advantage is only avaiable above rated altitude. The G-2 / G-4 without GM-1 and cockpit pressurizations will be lighter and enjoi an advantage in speed and climb up to their rated altitude over the G-1 and G3. but beyond rated altitude they will show significantly inferior performance. Finally, the G-4 owing to weight increases and aerodynamic drag increase by wing bulges / larger cooler will be slightly slower than the G-2 but may keep it´s top speed for a longer duration.
     
  16. Mitya

    Mitya Member

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    Such fairings (bulbes) can result in loss of speed in horizont... But how they can result in loss of 3 m/s (10 ft/s)!!? :shock: :shock: :shock:
    On foto Me-109G4.
     

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  17. kool kitty89

    kool kitty89 Well-Known Member

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    They shouldn't. There has to be other differences between the G-2 and G-4.
     
  18. Mitya

    Mitya Member

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    What?
    I above already have resulted figures from the report of scientific research institute of the Air Forces (NII VVS). A difference in weight of 4 kg, a difference in speed of 16 km/h, arms identical, power of the motor identical, and a difference in climb 3 m/s! Why?
    In a manual, which it is above resulted on G4, it is spoken only about distinction in radio station, but not in the basic characteristics...
     
  19. kool kitty89

    kool kitty89 Well-Known Member

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    No, I was agreeing the bulges in the wing from the landing gear should not cause that kind of change in climb performance.


    Was the propeller the same?
     
  20. delcyros

    delcyros Well-Known Member

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    Note that the difference shouldn´t be exaggerated. Each production aircraft has a margin of performance, not a pin point performance. The Werksgarantie for performances was only valid in within a margin below and above the legend perfromance. And there are actually dozens of reasons aviable to explain such a difference: the individual state of the engine beeing the most important.
     
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