Fw-190: the roots of the great roll rate?

Discussion in 'Aviation' started by tomo pauk, Nov 7, 2012.

  1. tomo pauk

    tomo pauk Creator of Interesting Threads

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    The Fw-190 was acclaimed as the plane with a great rate of roll. Why was it able to achieve that?
     
  2. spicmart

    spicmart Member

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    Sturdier, stiffer wings compared to other contemporaries; rod controlled ailerons that have no fabric but metal cover; small wing area. These are some things that come to mind.
     
  3. Siegfried

    Siegfried Banned

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    The Fw 190 had two spars that meant that the wing didn't twist from aileron forces which tended to cause control reversal from aeroelastic twist. The Spitfire with its single main spar suffered somewhat from this.

    The wing tips were quite thin which reduced stiffening at high speed.

    Friese ailerons reduced aerodynamic forces.
     
  4. drgondog

    drgondog Well-Known Member

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    #4 drgondog, Nov 7, 2012
    Last edited: Nov 7, 2012
    The FW 190 Did suffer twist/aeroelastic torsion in high G/High AoA manuevers. Two features contributed to this.
    1. Large effective ailerons
    2. Zero washout from 80% semi span to tip. At normal increasing AoA the lift Distribution was primarilt on the inner 40% (like a level wing approach/stall). But under high G/High AoA, the outer panel started to bend/twist and the lift distribution was shifted from inboard to outboard and the wing, then tended to stall completely at the high AoA rather than Inboard ----> Outboard progression .

    Gross, P. "Die Entwickland Tragwerkkonstruction Fw 190 -Bericht 176 der Lillenthall-Gesellshaft 2 Tiel, January, 1944"
     
  5. Siegfried

    Siegfried Banned

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    Of course all aircraft have aero-elasticity, in the case of the Fw 190 the twin spar wing box ensured relatively high torsional rigidity and therefore a high theoretical reversal speed; this being the speed the aileron imposed forces would roll the aircraft in the opposit direction.

    However there was a downside in that under high g the wing would twist so as to increase the angle of attack and therefore induce a premature tip stall with limited warning. Recovery was however immediate as the wing returned to shape. A single spar wing might twist so as to reduce AOA and so did no suffer from this issue.

    Ta 152 had a new wing structure, at least in the Ta 152h aileron control might be maintained post stall due to high 3 degree washout. There may have been other issues such as inertia cross coupling since the long nosed version lost roll rate.

    Thanks for the citation.

    Several US aircraft had good roll rates. P40, the P63, P51B onwards (only at high speed). High P47 roll rate was a myth.

    The thick laminar flow wings allowed a stiff structure and internal pressure balancing to reduce pilot forces.
     
  6. GregP

    GregP Well-Known Member

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    I think the Fw 190 also had great aileron gap seals, making the air flow over the aileron, rather than around it, better than other fighters.

    Gap seals are a BIG factor in roll rate.
     
  7. CobberKane

    CobberKane Banned

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    USN tests found that the Hellcat and Corsair could both roll with the 190, although they noted that the the 190 was more nuetral and easily controlled
     
  8. Siegfried

    Siegfried Banned

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    If it is the test I am thinking of it also noted that during high speed turns that the Fw 190s aileron Flutter was so severe that the vibration started to push the pilot into unconsciousness.

    This was in no way normal and indicates improperly rigged ailerons, which were a hard to setup due to the 190s pushrod system. Hence I would argue that the comparisons are not valid.

    Late war Corsairs and Hellcats received geared spring tabs that improved high speed roll rate at the expense of low speed.
     
  9. FLYBOYJ

    FLYBOYJ "THE GREAT GAZOO"
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    #9 FLYBOYJ, Nov 8, 2012
    Last edited: Nov 8, 2012
    With regards to rigging ailerons (and this is across the board) improperly rigged ailerons (deflection angles) will not flutter, rather give you varied turn rates and may cause the aircraft to fly "one wing low." Aileron flutter is usually associated with improper balance or "play" within in the control circuit (in the case of cables, under tension, in the case of pushrods, loose or worn rod end bearings).

    As far as the statement about "pushing the pilot into a state of unconsciousness." I'd like to see that report - if true; I think this statement is a bit exaggerated. If you're flying an aircraft that is experiencing aileron flutter that hard that you're blacking out, chances are other parts of the aircraft already self destructed.
     
  10. Thorlifter

    Thorlifter Well-Known Member

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    Very interesting thread. I only understand about 25% of it, but it's very interesting. I'm not trying to hijack the thread but was just wondering if WWI planes experienced the same effects. My complete guess is yes, but at a reduced effect due to much lower speeds.
     
  11. drgondog

    drgondog Well-Known Member

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    "High P-47 roll rate is a myth" If referring to NACA 868 it only illustrates the P-47C-1. Even so it was superior to all then existant USN and USAAF fighters except for P-63, XP-51 (<320mph) and P-40.

    A 'thick wing' in context of max T greater than comparable wing sections for a 'thinner wing' in absolute dimensions does offer some advantages on increased spar section Moment of intertia versus comparable 'shorter' beam with same web and cap material thickness. Note that the 'thinner' Spitfire wing had nearly the same absolute 'thickness' 'tallness', etc as the Mustang but the Spit spar was at ~ 25% chord and the P-51 was closer to 40% -

    The Spit wing was 'thinner' (in ration to T/C) simply because the chord was so much greater than the P-51.
     
  12. drgondog

    drgondog Well-Known Member

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    One other note about flutter. Even if properly rigged, resonance may occur at different flight speeds - causing the control surface to flutter.
     
  13. GregP

    GregP Well-Known Member

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    I have never seen any report claiming the Hellcat and Corsair could roll with an Fw 190, but have seen MANY rep[orts claiming the Fw 190 was superior at roll to everything it came against.

    Maybe a link to the report in question so we can read it?
     
  14. FLYBOYJ

    FLYBOYJ "THE GREAT GAZOO"
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    True Bill, but I think for the most case this will be more like a "buzz" at the stick.
     
  15. MikeGazdik

    MikeGazdik Member

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    Did the FW190 roll well at certain speeds, such as in the Zero only at lower speeds, or was across the board? I understand the Mustang rolled well at speed, and have read the Thunderbolt too. From reading I know the Corsair rolled well, but was it also across the the speed envelope? I knew the P-40 rolled well. Its news to me the P-63 rolled well, but I'm good with that!
     
  16. drgondog

    drgondog Well-Known Member

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    Google "NACA 868" to get a 1943 persective regarding comparisons..
     
  17. Edgar Brooks

    Edgar Brooks Active Member

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    How many more times must we refute this nonsense; the Spitfire had a mainspar, attached to frame 5 (the firewall,) and a rear spar (to which the flaps and ailerons were attached) attached to frame 10 (the former under the pilot's seat.) It also had Frise ailerons, and the early Mk.I, with fabric-covered ailerons, had an aileron reversal speed (calculated and corrected in 1942) of Mach .74
     
  18. cimmex

    cimmex Member

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    Didn’t all WWII planes had a rear spar to attach the flaps and ailerons? Please name a plane with a single spar wing. The Spanish Buchon which is currently going restoration at Meier Motors in Germany had a two spar wing or when you count the rear and front spar also then it is a four spar wing.
    Cimmex
    Buchon Yagen 2011-09-02(2).jpg
     
  19. Tante Ju

    Tante Ju Banned

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    The rear is only an auxilary spar on both the Spitfire and the 109. It isn't really capable of transversing loads. On the Spitfire the front, relatively thick D-seck of the wing - a legacy of the early evaporative cooling - and the main (centre) spar formed a D-shaped box, which was probably while the design had a tendency for wing flexing under aileron load. The 109 had a box spar design, where the main spar and the thick skin of the wing formed a torsion box.
     
  20. FLYBOYJ

    FLYBOYJ "THE GREAT GAZOO"
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    :rolleyes:
     

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