109G2 - just broke speed of sound

Discussion in 'Warbirds International' started by lepper, Jul 30, 2006.

  1. RolandGarros

    RolandGarros Well-Known Member

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    luftwaffe test pilot Hans-Werner Lerche liked the P-51b.
    "excelled in turning flight" are his words.
     
  2. Red Ant

    Red Ant Well-Known Member

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    Okay, I guess that's __NOT__ agreed then. I don't think a 109 with a heavy bomb can __safely__ pull the same number of G's as a 109 without a heavy bomb, and here's why.
    Imagine a rope. Just a rope with nothing hung to it. This rope has a certain strength, meaning it can only sustain a certain pull before it breaks. Now fix one end of this rope to something that rotates at an awfully high speed. With nothing hung to it, the rope can probably easily rotate fast enough that the outer end will be 'pulling' 100 G's. No problem ... after all this means the rope will only have to sustain (at the outermost point) 100 times its weight.

    Now hang a heavy rock to the outer end of the rope, say ... 50 kg. Unless it's a very strong rope, 100 G's will probably break the rope ... because most ropes aren't made to withstand a pull of 100 x 50 = 5,000 kg.
     
  3. Red Ant

    Red Ant Well-Known Member

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    Oh and what's more, THEORETICALLY, if a clean 109 can reach 12 G's there's nothing that stops a 109 with a heavy bomb from reaching 12 G's as well ... altho it might suffer structural damage from it. It will just have to produce more lift, which means it would have to fly at a faster speed and / or higher AOA.
    Notice the "THEORETICALLY" tho because obviously there's a limit to how fast a 109 can fly (and how hard a pilot can pull on the stick).
     
  4. -al---

    -al--- Well-Known Member

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    you can always take the airframe and swing it on a rope :)
    I bet ya the one with a bomb would break apart sooner :)
     
  5. Saddan

    Saddan Well-Known Member

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    Yes, there is something, the inertial damping effect of all the loads attached to the center of rotation... What makes an aircraft turn is the lift of the wing being directed towards other ways than up...

    You have the following system :
    ...................^
    ...................| Lift
    <--- Thrust (CG) Drag --->
    ...................| Weight
    ...................V

    When you roll and push the AOA of the wing, you direct part of the lift towards the side where you want to turn to, but this has a side effect of changing the Weight (and inertia) vector to the oposite direction...

    In this system the weight of the bomb will incread the weight vector arm, decresing the net result lift force (lift - weight) wich turns the aircraft, effectively decreasing the sustained turn rate. With lower turn rates you have lower G-Load, IE : It preemptively decreases the archivable G-Load by increasing the turn radius. The aircraft will turn slower and archieve lower G-Loads, not because of danger of ripping apart, but because theres not enought lift left to turn the thing...

    And theres a effect on instantaneous turn rates too, the force generated by the elevators will encounter a bigger mass, Same force on bigger mass = less acelleration...
     
  6. looseleaf

    looseleaf Well-Known Member

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    g load a factor of the constant "gravity" so far as we know.

    so if a plane can do 12g's in a turn it , it can "carry" 12 times it weight.

    now the same plane loaded with extra weight, be it bombs, pork fat, playboy mags or dancing girls it will take NOT be able to pull a 12g turn without breaking something permanently. That is it's "g-limit" is reduced.

    I think that's what they're saying..or trying to say anyway...
     
  7. Red Ant

    Red Ant Well-Known Member

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    Yes, in a world where our little 109 cannot compensate the added weight by increasing its speed (and thereby its lift) indefinitely, that's true.
     
  8. --stec

    --stec Well-Known Member

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    Saddan you have good knowledge of fphysics but you make mistake somewhere in your reasoning :).
    The fact is that bomb load (or any additional load) WILL decrease G limit the airframe can resist. Have you ever watched a glider doing aerobatics? It's wings bend upwards during loops (more in lower two quarts where G's are bigger, less on top) and tight high speed turns. Why? On the wings the centrfugal force is compensated by the lift force, but on fuselage is not - it produces the forces at the wing root trying to bend the wing upwards. If you make the fuselage heavier by attaching a bomb to it then the stress at the wing root will increase also making lower safe G's available for that plane. Am I wrong?
    Same with payload attached to wings: heavy bomb has quite an inertia, so any brutal stick moves and sudden flight direction changes will produce forces bending wings.
     
  9. Saddan

    Saddan Well-Known Member

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    It´s so fucking incoherent when people say that 109 have hard controls and at the sime time that it can archieve breaking point G-Loads... Don´t you understand that this is a mutually exclusive thing ?
     
  10. gandhi

    gandhi Well-Known Member

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    yes

    though plane with bomb has lower g tolerance for airframe it is wing that is limit factor

    a plane with bomb will stall at lower g than 'clean' plane

    built-in limit factor

    structure not even consideration unless bomb mount is weaksauce

    btw any1 even doublecheck original claim?
     
  11. gandhi

    gandhi Well-Known Member

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    look at dis plane

    [​IMG]

    capable of high g at under 400 kmh but control compress more & more above dis speed

    both can be true
     
  12. biles

    biles Well-Known Member

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    Entirely and completely and intentionally OT:

    OMFG that picture is beautiful.
    And what ship is that beneath? Is it like, um, mothballed?
     
  13. Saddan

    Saddan Well-Known Member

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    Increasing speed (Aceleration) is retarded due to increased Weight (F=MA) and increased Drag... Increses in lift (due to the elevated AOA) will lead to increased induced drag (The lift is felt by the thrust vector as if it was part of the drag vector)

    Theres no way, only a badly harmonized control will let an aircraft break with its certified load (Or, a Fly-by-wire aircraft with the fly-by-wire overriden by the pilot)
     
  14. Saddan

    Saddan Well-Known Member

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    Control compress = less torque applied to rotate the airframe = less pulled G-Load.

    the only way to archieve high-g loads is to have a very LIGHT elevator at very high speeds. This wasn´t a solution during ww2 era. By the lack of automatic harmonization of controls (fly-by-wire) aircraft tended to have just the exact elevator sensitivity, wich when carring a underslug bomb, lead to increased turn radius for the same stick pull.
     
  15. gandhi

    gandhi Well-Known Member

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    BS

    lookie track

    i fly on 12000m with 109g2 + 250kg bomb and 100 per-cent fuel

    when i go on dive i had ~66 per-cent fuel

    wing brake off @ 1100 kmh @ 7000m (mach .979 at this alt)

    fuselage fly on to 1550 kmh befor crash

    so 109 overmodel speed but not quite as lepper say
     

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    Last edited: Aug 15, 2006
  16. spuint

    spuint Well-Known Member

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    yeah
     
  17. Fucketeer

    Fucketeer Banned

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  18. --stec

    --stec Well-Known Member

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    Take a thin slat of styrofoam, balsa or thick cardboard, hold it in the middle and thrust forward like you wanted to punch something. It didn't break? Now glue or tape some weights at the ends and do the same. I'm sending you a case of good local beer if it didn't collapse at the moment you rushed your hand forward. Now try to pull sudden 5G's with 2x250lb's slung under fragile wings of a fighter plane. Understand what i mean?
     
  19. gandhi

    gandhi Well-Known Member

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    here is riddle 4 u:

    1. u have a plane that can fly a 9-g turn before wing stall

    2. u put 250kg bomb on belly of this plane

    assuming bomb stays on its mount can the plane fly a 9-g turn now?
     
  20. Helrza

    Helrza Well-Known Member

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    Fuck yeah, was thinkin the same thing.