Sunday, March 31, 2013

Left Wing Riveting Continues

Happy Easter!

After the Easter Bunny finished coloring and hiding Easter eggs, the DOG Aviation production facility was ramped up for riveting. Lots of rivets set today … 138 went onto the main spar alone.
                         Using the pneumatic rivet puller to set the first rivet into the line of rivets on the main spar.
                                                         Setting the 138th rivet into the left wing's main spar.

Because of the Easter Holiday, was only able to rivet during the morning and only an hour or so in the evening. Sadly did not finish the wing … but it is now about 60% or so completed. Everything is aligning perfectly which is a testament to the quality of Van’s components … especially in those areas where there are four layers of material.
                                                       Working on setting the last row of rivets for the night.

Saturday, March 30, 2013

Left Wing Leading Edge Closeout Complete

Today the first order of business was placing the W-1201C-L wing walk doubler into position on the wing using Clecoes. Now the upper surface of the entire left wing is ready to begin final closeout riveting.
                                              Left wing with all main top skins clecoed in position for riveting.

                                                  Riveting the leading edge of the wing in place.

                                                Setting the last rivet in the row where the bottom skins overlap
                                                 the top skins ... thus completing the left wing’s leading edge.

By this time I was tired of bending over so thought it was a good quiting point for the day. Good progress for the day overall. Oh, notice the lack of "Nanook of the North" clothing ... today was the first 50 degree day in a very long time making it a joy to work in the shop, although the sore muscles may disagree.

Wing Walk Doubler – Small Issue

Having spent most of the day running errands and dong chores on Friday, didn’t get into the shop until very late in the afternoon to finish up removing the rest of the plastic film from rivet lines of the W-1202B upper center skin and securing it onto the left wing skeleton.
                                            Removing blue protective film along rivet lines on the W-1202B-L
                                            upper center wing skin after melting the film with a soldering iron.

Fellow RV-12 builders will notice I’m not riveting the W-1201 wing skins just yet as called for in the plans. The plans instruct the builder to rivet the W-1201 skin except for the wing walk doubler area, then rivet the outboard W-1203 outboard skins, followed by riveting the W-1202 center skins. I suspect Van’s has the builder assemble in this fashion because of the large number of Clecoes required to do the entire wing at once. The number of Clecos they suggest necessary to build the RV-12 is NOT enough to Clecos to properly do the entire wing at one time (but keeps builder tool costs to a minimum). Early on in the project, the DOG Aviation procurement department procured many extra Clecos knowing they come in handy (and have already during construction of the tail cone).

In an effort to ensure the best possible uniform fit, all the skins are being secured in place onto the left wing skeleton before riveting. There are a few potential problem areas a builder should be cognizant of … in particular, those locations where a single flange (or tab) on the ends of the ribs are under the main spar and rear spar. Because I dimpled the rear spar along with all the W-1210 rib's single aft flanges, the dimple secured the single flanges so there were no problems here for me … but builders not dimpling should exercise care in both these areas.
                               Lifting the aft edge of the W-1202B-L skin and using a flashlight and mirror to verifying
                               the flanges under the main spar did not get pushed down from the rivet being inserted.

Builder tip:
The first thing I’ve been doing is verifying the tabs under main and aft spars are perfectly centered. Some tabs tend to want to move a tiny bit after they are positioned so once the skins are placed on the wing skeleton, the first thing I do prior to clecoing is use a center punch that is the same size as the rivet hole to center the tab then place a rivet into the holes that have single flanges BY HAND. This helps ensure there is not enough pressure on the rivet to bend the flange out of the way as the rivet is seated into the rivet hole. Placing a rivet into a rivet gun and shoving it into a hole at these locations is just asking for a flange to be bent out of the way and ultimately not riveted.

The last item that needed addressed was the wing walk doubler plate. Van’s has the builder place a couple of dimples in it and then set it in place to test the fit of the leading edge. (I of course, had already dimpled so those dimples were already there plus many more). The plans then say if the test fitting results in a gap, break the edge of the doubler to improve the fit. Can’t do it using a breaking tool because the rollers get hung up on the dimples! The breaking tool just won’t work AFTER the skin is dimpled! I worked and worked on the edge and spend a lot of time on it only making a small improvement … it would have been SO much easier to have broken the skin’s edge first prior to dimpling.
                          Using a metal plate to press the wing walk doubler tight to the edge of the workbench
                          while working the edge with a piece of PVC to place a small break on the edge.

Builder tip:
Do yourself a favor and break the forward edge on this skin before dimpling or even trial fitting … you will be glad you did.

The last task for the evening was to prepare the W-1201 skins for primer in the area where the wing walk doubler plate will be covering the top of those skins.
         Zinc chromate primer sprayed onto the portion of the wing where the wing walk doubler plate will be placed.

Thursday, March 28, 2013

Left Wing’s Top Skins Readied For Closeout

Today’s activities resulted in forward progress as the RV-12’s three upper skins are now positioned for riveting. The W-1201B inboard top skin was set in place a few days ago so today the W-1203B outboard upper skin was prepared for riveting by removing the blue protective film from the rivet lines followed by priming the areas that will be overlapped with zinc chromate primer.
                                                 Positioning the W-1203B outboard top skin to allow the built
                                                 in J-stiffener to slip into the cutouts on the W-1208 nose ribs.

After the W-1203B skin was in position, it was secured onto the left wing skeleton with Clecos.
                                Securing the W-1203B outboard top skin onto the left wing’s skeleton with Clecos.

The W-1202B center top skin is the last of the main top skins to be installed onto the left wing’s skeleton. The W-1202B skin overlaps the W-1201B and W-1203B inboard and outboard top skins, but is tucked under the aft edge of the W-1202 skin. Therefore, the forward row of rivets on this skin is the only portion that is overlapped and thus requiring primer. Zinc chromate primer was sprayed onto the skin outside and the skin was then brought inside to be flash dried using a heat gun. One nicety about using a self etching primer, such as PTI’s zinc chromate,  it can be flash dried by carefully using a heat gun.
                                         Flash drying the primed forward edge of the W-1202B center top skin.

After flash drying the primer, the top center skin was set in position for removal of the blue protective film along the rivet lines. Ran out of free time so will finish up removing the blue film with a soldering iron and then Cleco the W-1202B skin onto the left wing skeleton tomorrow.
               My better half, Jan, helping to hold up the aft edge of the W-1202 skin out of the way so the J-stiffener
               on the W-1202B center top skin could be dropped into the cutouts on the W-1208 nose ribs.
                                                           Looking more and more like an airplane wing.

Wednesday, March 27, 2013

Landing Light Lens Tweaked & Left Wing's Leading Edge Rivets Set

Before beginning the closing out of the left wing, I thought it best to try tweaking the landing light lens a little more while access was still good. Following the advice of the EAA tech councilors, I first heated the entire lens and then spot heated the edge I wanted to reshape using a heat gun from inside the wing. The reason suggested for heating the entire lens, is to help prevent the development of streaks in the lens from uneven heating.

The shop was quite cold this morning so the heater was kept far away from the lens at first so it could warm up slowly. As the lens slowly warmed up, the heater was moved closer and closer in small increments while the ambient temperature was monitored.
              Preheating the landing light lens with a heater before applying a heat gun to the lens from the back side.

After about a half hour the lens was quite warm to the touch so a heat gun was used to heat the one edge of the lens that was bothering me. A cap for a 1 ½" PVC pipe was a fairly close radius for the area I was trying to tweak and it was pressed into the inside edge of Plexiglass from behind and held in place as the lens cooled. This was done to several locations but I was afraid to use a lot of heat gun, so perfection was not achieved but the end result turned out 100% better than it was. Now there is just a very small gap between the lens and the wing skin and not sure the risk trying to make it better is worth it … so it is time to move on.
                           Photo of the left landing light lens fit prior to heating ... note the large gap on bottom left.
                                                  Left lens after being heated and tweaked … not perfect, but a
                                                  much better fit was achieved, hardly any gap on the bottom now.

For some reason the reflection on the glass makes the gaps look larger than they really are compared to the first photo with the blue tape which has no reflection.

Moving on … it is time to close out a wing. The plans instruct the builder to rivet the first 5 rows of rivets from the leading edge aft on the W-1201,02 and 03 wing skins … excluding the rivets in the area where the wing walk doubler goes, because the doubler is riveted in place later. The aft 9 rows are left open to enable the aft edges of the three skins to be lifted up to allow the J stiffeners built into the top skins to drop into the cutouts in the W-1208 nose ribs.
                                Using a soldering iron to remove the blue plastic from the rivet lines prior to riveting.
                                                Setting the first rivet on the leading edge of the W-1201-L skin.
Setting the last rivet in the fifth row aft of the wing’s leading edge. Ready for the top skins to be set in place for riveting.

Monday, March 25, 2013

Final Trimming Of The Left Landing Light Lens

Since Mother Nature has not received the note yet regarding calendar Spring, the borrowed shop heaters were blazing away, yet again, thwarting off the cold in the shop. My original plan was to wait until warmer weather to finish trimming the Plexiglass landing light lens.  However, because of the way it fits and is installed, thought it best to finalize trimming the lens to final size prior to installing the left wing’s outboard top skin.

The plans instruct the builder to mark the front of the lens along the left and right edges of the opening cut into the W-1203L wing skin. The lens is then to be cut a 1/4" wider on both sides. I elected to just place blue painters tape on the inside of the lens and then transferred the measurements from the marks on the front of the lens to the backside of the lens so I could run the lens through the band saw.
                 Inside of lens marked with red ink so it can be “rolled” through the band saw to cut off the excess
                 material on the left and right sides … leaving the required 1/4" extra on each side of the lens.

I cheated and got away with cutting the lens in the cold shop by holding the lens in front of one of the heaters to warm it up prior to running it through the band saw. The lens was warmed up once again prior to making the second cut. Not sure if all that was necessary because I do have a fine toothed saw blade on the band saw but thought it wouldn’t hurt to stack the deck in my favor. The band saw made quick, easy work of cutting the lens.
                          Using the band saw to carefully cut the excess side material off the left landing light lens.

Once the landing light was cut, it was filed to the proper shape and sandpapered until all the edges were smooth with no groves or lines. (Still need to get some finer grit sand paper tomorrow to really polish the edges out nicely).
                                   Finished left landing light lens with backing strips in place ready for a trial fit.

I decided to temporarily mount the lens using screws with lots of washers so the screws won’t wear out the nutplates on the backing strips. Because I’m not totally happy with the fit, a thought that came to mind is to try heating the lens up now that it is secured in place and see if it will naturally take the shape of the opening or possibly do so with just a little pressure from the back along the edge where it does not fit perfectly. Tomorrow will try placing one of the heaters in front of the lens to get it preheated in the hopes the tension on the lens will help form it into the opening better when I apply direct heat to the problem area from the back side with a heat gun. It appears 280 degrees is the magic number to begin forming … but I just want to bend it a little, so hoping it can be accomplished at much lower temperature.
                           Left landing light lens cut to final shape and test fitted onto the W-1203L wing skin.