zsmith3rd(at)earthlink.ne Guest
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Posted: Tue Aug 29, 2006 4:36 am Post subject: 701 wing struts |
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John,
NO! Don't cut.....that is until you are really sure you need to.
The two-piece strut arrangement you have is the same as what was used prior to the one-piece arrangement.
ZAC apparently went back to the two-piece struts because of slight variances in builder technique (not all aircraft got built exactly the same, one-piece struts didn't result in proper dihedral).
Others may have a different approach, but in my case it took two people, one long day, lots of walking around, and a lot of measuring.
To make a long story longer, I would offer this: Level the airframe side-to-side first. Air pressure in the tires will do this.
Second, get both wings up into position and supported by tall sawhorses, ropes, ladders, whatever. You cannot just hold them up.....arms tire quickly and nobody can hold them still long enough for a real measurement.
Drill the front spar attach points first. With bolts installed at the front you can then sight down the front of the wing from one tip to the other (use a string, too) to get them straight. Make sure the wing is "square with the airframe" by measuring from wing tips to a convenient point near the tail (just mark a spot on top center of the fuselage with a marker, measure to this point).
You can then drill the rear spar attach points. Some trimming may be necessary for access to the bolts. This will be obvious when you get to that point. There is a note, either in the manual or on the plans, as to the position of the trailing edge in relation to the top of the fuselage.
Once the wings are attached, fuselage level, you can work on dihedral. We used a 'smart' level (electronic) and a string/ruler. My "assembly manual" is the old type-writer version and is a bit lacking as to detailed instructions, but once you have the wings attached at the inboard end the strut business becomes somewhat less foggy. The string should be on the front spar as I recall..... stretch it tip-to-tip and tie a 10-inch Cresent wrench (weight) to each end. This will probably give sufficient "tight" to the string for your dihedral measurement at the first rib.
Put tags or tape on the strut pieces and label them.....left, right, forward, aft, inboard, etc. The strut piece which slips INSIDE is the inboard/downhill half of a pair. Lay them out on the floor and see that you aren't making a sad mistake. You will cut off the upper end of the lower half, NOT the bottom end of the upper half. We only cut off about 3/4" as I remember, and I don't recall if we had to cut all four......whatever fits.
We raised and lowered the wing tips dozens of times before we drilled the first hole. Remember, you only get one screw-up per strut. We drilled one 1/8" hole and stuck a cleco in the hole, one per strut, then drilled the remaining two holes in a drill press, pulled the cleco and drilled the third hole. Plans show the bolt directions. Make sure you keep track of "pairs" and left-right, front/rear because that's the only way they'll fit after you drill the first hole.
Also, don't attempt to support the wings with just the one cleco; keep the wings supported until the bolts are in place. The weight of the wings will shear a cleco and ruin your day.
The online ZAC assembly photos may be helpful.
This will make more sense AFTER you finish.
Regards,
Zed/701/R912/90+%/etc/do not archive
And make sure you have plenty of refreshments....it will be a long day.
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