flyenforfun

flyenforfun

Well Known Member
Hello everyone,

I need some advice here. I am at the point where I need to mount the wings and set the incidence (RV8). I will be doing this in my back yard so this install wont be permanent. Here are my questions..

First question is should I definitely use temporary hardware store bolts for temporary mounting and setting the wing incidence? Wouldn't the real bolts torqued to the proper value be more accurate for setting the wing incidence? Do I only need the 4 large bolts or should I put the smaller 4 bolts in also?

Do I need to grease the bolts if they slide in ok as is?

What have you guys found is the best method for measuring and setting the wing incidence?

All the help you can give me before I give this a shot is appreciated. I always end up looking back and thinking "man i should have done that this way".
 
Use the hardware bolts and you only need the big ones. DON'T use a digital level use a good bubble level or do like I did and used a machinist level. I used four stings off the leading edge and a laser to set the sweep. Measure, measure again, go do something for a couple of hours and measure again. Make sure you have the edge distance on the rear spar and drill. If you get it perfect you will have a nice flying airplane. Don
 
my main reason for not using the NAS bolts is that im afraid of tearing up the unside of the spar holes.
 
Water Levels

I used them every time I could. I believe them to be the most accurate of all. Even the touted digital levels can have some error. If you do use water levels use tubing that is at least .25" ID otherwise capillary action might screw things up.
 
For this application, I doubt a super accurate level is all that necessary. After all, how many builders can precisely size the required 2-51/64" block or spacer that the plans call for? If that measurement is off by even the slightest amount, I kinda doubt a super precise level is going to mean very much.

I inserted 2 or 3 large hardware store bolts per wing. Not strictly necessary, oiling or greasing the bolts prior to insertion cannot hurt a thing. I only very loosely snugged the temporary bolts using washers and nuts. Make certain the airframe (main longeron) is perfectly horizontal and verify with a level placed atop the sill. Then, using the appropriately sized block or spacer located atop the rear spar and a reasonably accurate level of your choice resting atop the wing main spar, level the wing. You may have to shift the wing up or down a bit to achieve level. Clamp and secure the wing so that it cannot shift out of fine adjustment. The next very important step is making certain you have adequate e.d. at the rear spar bolt attach point. For optimum hole quality, I used a number of drill blocks to help keep the drill bits perpendicular with the work and drilled the hole up to full size in a series of steps. For instance, I started by locating and drilling a #30 pilot hole then brought that pilot hole up to .1875 (3/16"), then .2500 (1/4"), then .2969 (19/64") and finally used a lubricated reamer for the final pass. Because I possess that size in my reamer collection, I used a .3110 reamer instead of a .3120 reamer for the final pass and found the AN5-10 rear spar attach bolts to fit nice and snug.

9vkplf.jpg
 
I tried three different digital levels. They are fine for getting things close. I found I could get both sides even with a digital and then use the machinists bubble level to get it exact. i found I could move the rear spar up and down up to 1/8" and the digital would not record a movement. The machinist level will drive you crazy because it is so exact but you will get both wings exact. When I have my airplane trimmed for cruise I can pull the throttle back and they remain trimmed all the way to stall. Don
 
It looks like most replies are in regards to what levels to use and how to use them. Although I am no expert let me give my thoughts on the hardware bolt issue.

First question is should I definitely use temporary hardware store bolts for temporary mounting and setting the wing incidence? Wouldn't the real bolts torqued to the proper value be more accurate for setting the wing incidence?
Click to expand...
Yes, you should definitely use the hardware bolts. The truth is the hardware bolts are not necessarily a different size than the supplied bolts for your wings. Actually, the tolerances on the HW bolts may be very close to the "close tolerance" bolts you will use in the final assembly. They just are not manufactured with the same tolerance requirements as the supplied "close tolerance" bolts. The reason to use the HW bolts is to keep from damaging the supplied bolts during the time you will be installing and removing them to work on the wing. I think you will notice once the temporary bolts are in place you will find the wing is still a very tight fit.

If you are concerned that there may be a difference in alignment you might think about using the temporary bolts in the wing while doing everything else that is necessary to work on except drilling the rear spar. Then when you know you are ready to drill the rear spar do that as the last task to perform before you put the wings on permanently. At that point you can install the actual wing bolts and do all the alignment needed to set the incident with these bolts in place. Of course you would have to plan to do this at a point in your build when you do not anticipate taking the wings off again. Just something to think about.

Do I only need the 4 large bolts or should I put the smaller 4 bolts in also?
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Just use the large bolts. Anything else will be overkill. If your install and removal was like mine you will be cussing them as you work on removing them. This is where the other wise installers before us have recommended grinding the HW bolts to create "PINS" for temporary installation.

Do I need to grease the bolts if they slide in ok as is?
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I would not use grease as I would be concerned about any residual grease getting on the threads of the final assembly bolts when you are ready to install them. The truth is the bolts will slide in if the correct alignment of the wing is achieved.

I installed my wings this past January on my 9A. What I found was the difficult part of wing installation was not the installation of the bolts in the wing/spars. The real problem (at least on A models) was getting the nuts and washers on and tightened down. The gear weldment was so tight to the bolts that no wrench would get into the space and align with the nuts. I ended up wedging a crows foot socket between the nut and the weldment and tightening the bolt head until the nut cinched tightly. This was far more difficult than actually installing the bolts in the holes.
 
Thanks for the help everyone, great information! I will post pictures when complete. Waiting for a weekend of good weather.
 
I Know I posted in April that I was going to do this soon...
Well I put the wings on yesterday with Hardware bolts. Today I removed the left wing and trimmed some off the fuselage skin opening to add clearance above the top of the spar. Then I put in the rest of the 16 hardware store grade 5 bolts, and 'snugged' the big ones.
I then used a manometer (tygon tube) to level the airframe (less than 1/10th inch wing tip to tip!) checked the sweep and triangulated the wings to the fuse. All were right on. I'm very pleased, but also wondering what I would do if it wasn't right? the assembly is actually pretty stiff.
Fortunately I stopped long enough to search this forum, and found out about VAN's PDF file "Wing Incidence Drilling Simplified". It's been added since I got my plans.
Fitting the flaps at this point, prior to drilling the rear spar, and checking wing incidence against horizontal stabilizer incidence makes good sense. That's on tomorrow's work list, after I ride with the wife as her "Safety Pilot" while she stays current with the IFR thing.
I just want to add here that putting the wings on was not a very big deal after all!! I had made this thing into some kind of "Big Deal" but with two sons and a wife to help, it just slid right in. We used a screwdriver to gently spread the rear spar attach 'hand', fingernails to hold the lower fuselage skin down so the wing would pass over it, and hold up on the wing spar butt a bit while sliding it into the fuselage. The tapered polished & greased alignment bolt went right in, the rest of them followed easily.
I removed & re-installed the left wing by myself later. The support jig was just plastic 5 gallon buckets, a plank a ladder and a bunch of rags for padding.
 
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Just a continuation...
Today I spent 10 hours (a Marathon!) working on the RV-8.
I fit the flaps, which involved trimming the top inboard skin to match the fuselage curve. Van's template is a good start, it narrowed the flap enough to insert the hinge pin, but lifting the trailing edge of the flap was out of the question. I used the Sharpie pen to mark out iterferences, then the cut off wheel or the 3/8 wide pistol grip belt sander. You just gotta have one of those.
I ended up with the inboard bottom flap skins a bit low; it does not lay on the bottom of the fuselage, but it is about 1/8" away, so I accepted that and did a final incidence check, along with fuselage level, wings level, and check the Horizontal stab incidence, then started looking for the rear spar bolt location. Edge distance didn't look like it was going to be a problem, but I hit on an easy solution for selecting 'The Spot'. The kit includes a pair of large flat washers, 1 3/8" OD with a 1/4" hole. I just moved this around across the back of the spar connect area until all the mating parts had equal-or -better edge distance beyond the washer, then I center punched the hole in the washer, and marked the washer hole circle with the pen to identify the punch mark.
I made a drill guide on the lathe from some aluminum round stock, center drilling it #30, then facing it. The rear spar, I drilled about 1/2 way thru the first strap, so the #30 drill would center in it, then 'C' clamped the drill guide in place, pulled out the short drill bit used for alignment, and drilled it with a #30 jobber drill. Now I can 'pin align' the jig, and outside mark it for the final holes before reaming tomorrow.
 
All the electronic levels do is get it close. I used a machinist bubble level on mine. It drove me crazy as just the slightest movement and the bubble would go off scale. It payed off though with a very straight flying airplane. Don
 
Im just curious about the back yard, does that mean on the lawn or do you have a large patio. If the lawn how do you plan on setting the sweep.

Pat


flyenforfun said:
Hello everyone,

I need some advice here. I am at the point where I need to mount the wings and set the incidence (RV8). I will be doing this in my back yard so this install wont be permanent. Here are my questions..

First question is should I definitely use temporary hardware store bolts for temporary mounting and setting the wing incidence? Wouldn't the real bolts torqued to the proper value be more accurate for setting the wing incidence? Do I only need the 4 large bolts or should I put the smaller 4 bolts in also?

Do I need to grease the bolts if they slide in ok as is?

What have you guys found is the best method for measuring and setting the wing incidence?

All the help you can give me before I give this a shot is appreciated. I always end up looking back and thinking "man i should have done that this way".
Click to expand...
 
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