Couple of Rigging Concerns???

Discussion in 'Steen Skybolt' started by mjk51, Sep 14, 2018.

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  1. Sep 14, 2018 #1

    mjk51

    mjk51

    mjk51

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    Well there is no longer room for the wife's car in the garage.:D
    wings bb.jpg
    I started rigging the wings for the final pre-cover adjustments. Getting the I-struts and slave struts tweaked.
    The right side wings came in great with one shim washer on the top rear of the I-strut. Top wing 0.0 degree dihedral and 2.0 degree incidence. Lower wing 2.5 degrees dihedral and 2.0 degrees incidence. Right at spec.
    Left wing not so great. I feel like the proverbial monkey and the football here. Could use some advice.
    I can get both left wings in spec for dihedral but the wing attach bolts at the lower left wing root have me lock in to about 2.4 degrees of incidence on the lower wing. I can "twist" that out near the wing tip to 2 degrees. If need be. My question(s)...Will a 0.4 degree variation in dihedral from right side to left side be unmanageable, unsafe ? Should I plug and re-drill the left rear wing attach fitting? My hunch is that even 0.4 degrees is too much. It seems the only other solution is the move the left attachment point. (Next time maybe drill the fitting when you rig it Mike).... :(
     
  2. Sep 14, 2018 #2

    Vic Zubot

    Vic Zubot

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    The plans revision in 1990 says wings should be at 1.5 degrees incidence top and bottom and the dihedral at top wing is 0 incidence and lower wings +1 degree incidence. Horizontal stab at +.5 to +1 degree incidence more than the main wings. In other words +2 to +2.5 degrees relative to the top longerons. I would not twist the wing, I would redo the lower wing to fuselage fitting if it is not right.
     
  3. Sep 14, 2018 #3

    mjk51

    mjk51

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    For clarification the aircraft is a Firebolt. The specs I enumerated are from the prints. If they have been changed I am not aware of it.
     
  4. Sep 14, 2018 #4

    StinsonPilot

    StinsonPilot

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    Are you using a digital level?
    They'll drive you nuts trying to get a few tenths of an inch.
    Use a bubble level... Things will look a lot better.

    I don't think .4 will matter.
     
    biplanebob likes this.
  5. Sep 14, 2018 #5

    Larry Lyons

    Larry Lyons

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    Ditto to everything Doug said. Digital level will drive you straight up.
     
  6. Sep 14, 2018 #6

    mjk51

    mjk51

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    Have been using a digital level.... with rigging boards. Will have to run some trig to get the angles with a bubble level. Your right though... the digital level is damn touchy. Maybe I am over thinking this thing.
     
  7. Sep 15, 2018 #7

    TFF1

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    Not going to matter one bit. I think if a Cub tail post is within 3", it is normal. At least that is how they left the factory. Yours is probably straighter than most.
     
  8. Sep 15, 2018 #8

    IanJ

    IanJ

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    I've always been amazed at how loose the tolerances are for certified aircraft of that era. They were banging them out in a hurry, though, and most of them fly pretty well.
     
  9. Sep 15, 2018 #9

    TFF1

    TFF1

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    I think that is why all classic homebuilts are rag and tube. Hack saw and torch. Then glue some wood. A person at home can make one and it will fly. RVs were about equal with respect to build numbers when they were plans built. The nice kits are what made them popular. Drilling all those holes in blank aluminum takes a long time and it's hard to fix if you are wrong. Today a lot more effort is put into building because the cost and probably specific niche like aerobatics, instead of get it done like the old days. Who would have thought then, their plane would be flying 50 years later?
     
  10. Sep 15, 2018 #10

    Vic Zubot

    Vic Zubot

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    I have corrected my first post the top wing is 0 degrees dihedral and the lower wing at +1 degree degrees dihedral.
     

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