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zsmith3rd(at)earthlink.ne
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 Posted: Wed Jan 24, 2007 7:27 am Post subject: 701 wing addendumb..... |
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Okay, I omitted a couple of steps. Sorry 'bout that. Hopefully here are some helpful additions:
The reference mark I mentioned previously refers to making a mark on top of the fuselage, on the centerline, and as far aft as possible. You can use this as the point from which to square the wingtips with the airframe.
The dihedral could be set with one flat tire (aircraft tilted) but it just doesn't look right. Place a level across the top of the fuselage from one front spar attach point to the other. If this doesn't establish level then nothing will.
As for the fore-aft level argument, I didn't worry about it.....the front & rear attach points on the fuselage are fixed and you will be centering the front and rear spars on these regardless of how they sit in relation to the floor. Remember, some of this is "art" as opposed to "science".
First of all, my hangar has a bi-fold door. There are several horizontal structrual members on the door which make a nice visual reference. If the completed/attached wings are viewed from the opposite end of the hangar it is easy to see if things are "equal".
I used padded 2x4 lumber running fore & aft under the wings, with one placed about a foot outboard from the inboard end, and another about a foot outboard of the strut attach brackets, to suspend the wings from the hangar trusses. Slats and ailerons were removed. This was only for attaching the wings to the fuselage; you may opt to support from below. The strut attachment requires firm, non-moving, support.
I had already attached the tail feathers prior to attaching the wings. Looking at the airplane from about thirty feet in front or rear gives you a sense of what is right/correct. Probably no different from the method used by Orville & Wilbur. (Did they have measuring tapes in those days?)
Key to all this is that the front wing spar attachment tab is centered VERTICALLY at the FRONT FUSELAGE SLOT.
If you built the wings relatively straight/flat/etc, then also center the rear spar attach points vertically on the rear fuselage attach points. This will insure that both your wings will be alike WHERE THEY MEET THE FUSELAGE.
The really difficult task is the strut attachment. I installed left and right FRONT struts first.
This establishes the dihedral (the 75mm/tight string).
Others may offer varying methods, but I suggest you round up something substantial to support the outboard end of both wings. The golf cart just happened to be handy. Mine has a sloping roof.... I discovered that by pointing it toward the side of the fuselage I could roll it in/out at the wingtip and thereby raise/lower the wing. A tall (and STURDY) sawhorse will accomplish the same thing. A bundle of wood shingles from your local lumber yard will make nice shims. Both tips need to be supported properly during this exercise.
Attempting to suspend the wings on ropes while making the struts fit is an exercise in futility......ropes tend to sag/stretch and you will waste a lot of time re-adjusting them, and you may not get things as straight as necessary. Chain hoists might be suitable if you have enough overhead room to accomodate them...at least there is no stretch with the chain.
The ends of the struts, where they attach to the fuselage & where they attach to the wing, should be drilled/fitted first. Drill #30, then enlarge, insert proper bolts. This allows you to hold the "middle" ends together (side-by-side) to see how much needs to be cut from the bottom half to make things fit. (Observe that there is a male and a female....the female is the upper/outboard half of each strut set). You may or may not need to cut, depends on kit variations; I cut about 20mm from the rear, none from the front, yours may differ.
Once you have both FRONT struts cut to length, bottom half inserted into into top half, fuselage & wing strut bolts inserted, you are ready to drill the strut "splice". This is the critical part as it sets the dihedral. Back off and eyeball your work. Re-measure the 75mm/string. Take a break, have a sandwich.
There are three bolts which join the strut halves.
When you are sure you have it right you can drill ONE hole. I suggest you drill a #30 and insert a Cleco, remove the top and bottom strut bolts (fuselage & wing) and take the entire strut to your drill press. (This is the reason for good supports under the wingtips)
Drill this first hole in BOTH front struts while you have everything sitting right/straight/correct; removing the strut tends to wiggle the entire airplane.
Leaving the Cleco in place drill the 2nd hole and insert a bolt, drill the 3rd splice hole and insert another bolt, remove the Cleco and drill out the 1st hole to bolt size and install the bolt. Masking tape and marks with a Sharpie will help to keep the builder aligned.
Hint: Can't see any reason that you couldn't put a rivet in the first hole....nothing slips or moves and you'll just drill it out later; and you won't get one strut half mixed up with another strut half before the real holes are drilled. Again, be sure to mark your struts with tags/tape/etc for peace of mind. A long tapered punch helps when re-installing the struts.
Once the front struts are in place you will find that the rear struts are easy.....same process, but you'll need to measure finished length of the rear struts. Pushing up or down on the trailing edge of the wing is the equalizer.
Getting one rear strut longer/shorter than the other is okay if you don't mind flying in a circle. (See Trim Tabs 101)
As previously stated, there may be several other methods, but this works. What is of prime importance is that you back off and view your work before you drill, keeping in mind that you really need to drill all original holes as #30 then enlarge these later simply because a new, sharp small bit will put a hole where you intended rather than drift as the larger bits tend to do in a handheld drill motor.
The attachment of the wings requires some help. I'm sure some have done it alone, but I suggest you do not attempt it except as a last resort. Dropping a wing on the floor will ruin your day.
Jury struts are not addressed here.....you'll see why later.
Next week we'll discuss proper methods of refurbishing ScotchBrite pads.
Regards to all, and my apologies to those who have already been there-done that. This is intended as some help for those who have been putting this chore off in hopes the wings might magically install themselves.
Zed/do NOT archive
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roger(at)nwtradingpost.co
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| Posted: Wed Jan 24, 2007 8:54 am Post subject: 701 wing addendumb..... |
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Zed
Thanks, this is very helpful
Roger Venables
Kenmore, WA CH701
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Geoff Heap
Joined: 12 Jan 2006
Posts: 266
Location: Lindenwold, New Jersey
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| Posted: Mon Jan 29, 2007 5:50 am Post subject: Re: 701 wing addendumb..... |
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Thanks Zed
Geoff Heap 701/dual controls/912 rotax ordered/Looking at Enigma/
do not archive
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