BF109 Ruder trim?

Discussion in 'Aircraft Requests' started by Marcel, Oct 13, 2007.

  1. Marcel

    Marcel Well-Known Member

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    Last week when I was at the RAF museum in Hendon, I saw a BF109G. Looking at the tailplane I wondered, where's the ruddertrim? See the picture below.
    Usually you can see those little ruders in the vertical rudder but not on this one. Did I miss it somewhere? Was it normal on a Bf109 to not have a ruder trim? If so, had they other means of directional trim?
     

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  2. FLYBOYJ

    FLYBOYJ "THE GREAT GAZOO"
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    Was that a G-2? I've seen several photos of G-2s without rudder trim.
     
  3. Marcel

    Marcel Well-Known Member

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    yep a G-2
     
  4. Wurger

    Wurger Siggy Master
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    It is true.The F and G ( especially early Gs) didn't have a rudder trimtabs.It depended on the kind of fin and rudder which was mounted to the fuselage.
     
  5. pbfoot

    pbfoot Active Member

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    heres the E4 and it has a piece of flexible metal which is the red piece
     

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  6. Wurger

    Wurger Siggy Master
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    It is a common way for Bf 109 to balance the rudder.
     
  7. Downwind.Maddl-Land

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    Unlikely as it seems, the Bf-109 didn’t have any adjustable rudder trim. As Capt Eric “Winkle” Brown records of the ‘109G in his series ‘Viewed from the Cockpit’:

    “A shortcoming was the lack of any rudder trimming device. This meant that is was necessary to apply moderate right rudder during the climb and considerable left rudder during a dive. Thus, although the Bf-109G pilots tended to bunt into a steep dive as an escape manoeuvre in dogfights, they had some very heavy rudder and elevator control forces to contend with as speed built up and pull-outs at low level had to be made with considerable circumspection.”​
    The red trim tab on PB’s photo of the ‘109E looks like a fixed tab that would have been set, after much trial and error and numerous test flights, by the ground crew as the best compromise over the aircraft’s performance range.
     
  8. Marcel

    Marcel Well-Known Member

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    So the flexible metal is used as trim then? Could it be operated from the cockpit?
     
  9. Marcel

    Marcel Well-Known Member

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    ha clashed posts. So you think this piece of metal was only used to couter the plane's natural directional instability?
     
  10. Downwind.Maddl-Land

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    Yep, that's about it. Use it to take out the individual airframe manufacture error and presumably set it for most comfortable cruise position......

    However, following on from Wurger's comment above, I have just found a cutaway drawing of a G-14 with the bigger wooden fin and rudder that shows a 'Geared Rudder Tab' so it looks as though the issue was addressed later in the conflict
     
  11. pbfoot

    pbfoot Active Member

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    not a chance I'm assuming its flexible but am not going to pull on it to try. i would guess one or two flights would set it up. Maybe some one can translate the word after Nicht
     

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  12. Marcel

    Marcel Well-Known Member

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    Nicht anfassen= don't touch.
     
  13. Wurger

    Wurger Siggy Master
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  14. Marcel

    Marcel Well-Known Member

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    That's quite late, isn't it? I mean, most planes at that time had these trim surfaces. Why on earth didn't they put one on the Bf109 in the first place. I mean must have been quite a starin on the pilot with the big engines at all.
     
  15. Downwind.Maddl-Land

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    Check out the accident rate of 109G's and you'll see how right you are! Bit of a bu**er on landing I understand.........
     
  16. Wurger

    Wurger Siggy Master
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    As memory serves,the rudders of Bf109s were balanced in a factories.Therefore there wasn't any possibilities to do it later.
     
  17. Marcel

    Marcel Well-Known Member

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    I alway thought that was because of the narrow undercarriage.So additional of tis problem they had a trim problem as wel eh?
     
  18. FLYBOYJ

    FLYBOYJ "THE GREAT GAZOO"
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    Gentlemen - the rudder trim on take off or landing doesn't mean a whole lot - its in cruise flight or applying power in the climb where the rudder trim will relieve a lot of pressure on the legs.

    During take off and landing you are "dancing" on the rudders, making little adjustments for P factor and any cross winds affecting the aircraft on roll out. With 1600+ HP you better be pretty light on your feet to keep things straight....

    And Wurger, you are correct - the rudder is initially balanced at the factory. The only time its re-balanced if it is recovered in the field.
     
  19. pbfoot

    pbfoot Active Member

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    don't blame the undercart it's 6" or 12cm wider then the Spits
     
  20. FLYBOYJ

    FLYBOYJ "THE GREAT GAZOO"
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    To add more to this discussion - rudder trim would be an advantage on approach with a steady crosswind - again more of a luxury but still taking a bit of a load off the pilot.

    In the past several months I have had a chance to fly quite a bit at work doing engine break-ins. Now that I have some experience under my belt in the Super Cub, I believe I've come up with some reasoning for the alleged high accent rate on the Bf 109...

    1. Too fast on the flair - trying to get the plane down fast and not being quick enough on the rudder.

    2. Not bringing the stick all the way back in the flare - on a nose heavy tail dragger you've got to get that sick in your belly and keep it there.

    3. Allowing the aircraft to "bounce" and inducing pilot induced oscillation - See item 2. There is a tendency in a bounce to come forward with the stick - the tail will come up and the aircraft will continue to fly.

    4. Dirt or grass strips - not the smoothest surface to land on. Combining 1 - 3, a good crosswind plus a low time pilot, you have an accident waiting to happen.

    5. Not adjusting the controls for winds when on the ground during taxi. In a head wind the stick needs to be back, in a tail wind it needs to be down - ailerons also have to be adjusted for quartering winds as well. I'm sure there were hundreds of nose overs all all sides because of this.

    I believe these are the big hitters for this situation and for some reasons the Bf 109 had this reputation. I'm sure there were many a pilot low on fuel trying to get that plane down quick with too high an airspeed in a cross wind and rolling on a rutty grass or dirt field.
     
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