Thursday, November 29, 2012

Countersinking Left Wing Spar Continues

Another late afternoon start resulted in not much forward progress on the left wing spar.  However, that said, the spar was rearranged today to make the countersinking process go easier. Yesterday, the spar was placed on edge vertically while countersinking … but after countersinking a few holes, decided it may be best to try laying the spar horizontally. So the spar was propped up on a few 2X4 scraps to protect the rib mounting tabs in the hopes it would allow for better control of the countersink cage. This position proved to be a good move and offered much better control of the countersink cage.
               Left spar propped up horizontally on 2X4 scraps offering much better control during countersinking.

While using the countersink cage, discovered for some reason starting and stopping the countersink bit by pulsing the drill trigger while applying steady pressure on the drill seems to  cut the countersink faster than just leaving the countersink bit steadily rotating.  This phenomenon was discovered during the last few holes countersunk today, so will have to evaluate that further tomorrow.

Wednesday, November 28, 2012

Tentacles Of Winter Reach DOG Aviation

The photo below was taken a couple of days ago during the first snow of the season here at DOG Aviation. We only received a light dusting of snow, but it is a reminder the tentacles of winter are about to get a firmer grip on northeastern Ohio.
                                    The temperatures have dropped significantly which produced the first dusting
                                    of snow at DOG Aviation captured here by the photography department.

Bernie and Mike (two of my childhood friends from the old neighborhood) have taken pity on me and loaned me a couple of propane heaters to use in the shop when the winter temperatures get nastier. Thinking of safety, a carbon monoxide detector was procured as an added safety margin. Of course, no good deed goes unpunished and to coin a phrase from one of the songs by Tom Waits “the large print giveth and the small print taketh away”. While reading the detector’s instructions, discovered the detector is only rated down to 40 degrees ... that sucks! Guess a frozen detector is marginally better than no detector at all, so will mush on exercising extra caution whenever the heaters are in use. The roll-up doors are not weather sealed and there is a significant gap between the doors and the frame so there should be plenty of fresh air getting inside the shop ... plus there are a couple of vents on the roof but guess they will be out of play whenever there is significant snow on the roof.
             Propane heaters on loan to DOG Aviation from Bernie and Mike – should be a big help, thanks guys!

Between the Thanksgiving holiday, company, family medical issues, and setting up a new MP3 player for use in the shop, not much has been accomplished on the RV-12 since priming a few of the remaining wing components on Thanksgiving morning. My arm has still not fully recuperated from the marathon wing skin dimpling sessions, so the delay has been somewhat welcomed in that regard. Today work resumed on the RV-12’s left wing spar which is being machine countersunk for the 120 degree flush rivets being used in place of the LP4-3 rivets for the project.  There are oodles and oodles of holes in the spar’s upper and lower flanges which require machine countersinking … so this will be a mini project in and of itself.
                                          Beginning of the countersinking on the left wing spar for flush rivets
                                          using the countersink cage and the 120 degree countersink bit.

I may have mentioned this in a previous post but as a reminder for those interested ... using an adjustable air flow control with the air turned down really low makes a big difference. Countersinking the aluminum with the countersink bit spinning slowly coupled with some liquid Boelube virtually eliminates two issues … rivet hole elongation and countersink bit chattering - which creates flat spots on the countersink taper. Granted the spar material is thicker and somewhat less prone to rivet hole elongation … even so, spinning the countersink bit slowly and well lubricated makes a noticeable difference.

Thursday, November 22, 2012

A Happy Thanksgiving!

In addition to celebrating Thanksgiving, there is another reason to celebrate at DOG Aviation … all of the components for the RV-12’s wings are now primed and ready for assembly.

Today the remaining three flaperon aft skins were deburred, then dimpled … and together with the one previously dimpled aft skin, passed onto the paint department for priming. The temperatures were in the low 50’s so the rattle can PTI zinc chromate primer was used to finish off these last few remaining wing components requiring primer.
                       Primed flaperon spars and aft skins … nose skins are in background above air compressor.

After all the skins are fully dried, the shop will need to be arranged to accommodate assembly of the left wing skeleton.  As the wings take shape, things are about to get really big real soon, which will be both exciting and scary as the amount of free shop space begins diminishing drastically.

Wednesday, November 21, 2012

Flaperon Spars Dimpled And Primed

Knowing there will not be many more days in the low 50’s, decided to dimple and prime the flaperon spars. The dimpling went rather fast and I was able to set the pneumatic squeezer on the bench at the perfect angle for dimpling the flaperon spars without needing to hold its weight … the right elbow is still complaining about the abuse it took during the marathon wing skin dimpling sessions.
                                             Using the pneumatic squeezer to dimple one of the flaperon spars.

After the spars were dimpled, went ahead and began dimpling the aft flaperon skins after a quick deburring.
                                        Using the pneumatic squeezer to dimple one of the aft flaperon skins.

The “winter” primer came from Aircraft Spruce on Tuesday so decided to try it out on the flaperon’s  spars and nose skins.  Aircraft Spruce stocks the PTI chromate primer (which the data sheet says will work as low as 40 degrees) in two colors a dark gray/green and yellow. I chose the yellow … yep, it’s bright to be sure. However, it is possible to order custom colors and I thought about custom ordering a shade that matched the Akzo primer used up to this point … but knowing there were 50 degree days today and tomorrow for priming I did not want to wait for custom colors.

One can of the PTI chromate primer painted both flaperon spars, four small brackets and one of the flaperon nose skins. It comes out of the can nicely and is easily applied in a thin coat. The DOG Aviation procurement department purchased a neat spray can holder at Home Depot and aircraft supply made by Rust-Oleum  ... which I’m happy to report, worked wonderfully. It has a good feel and nice trigger which makes using a spray can feel more like using a spray gun … plus, there is no paint on the fingers nor the customary large dent in the finger from depressing the paint nozzle.
                             PTI chromate primer and the new spray can holder from Rust-Oleum which works great.

All the flaperon nose skins are now primed and the plan is to finish priming the aft flaperon skins Thanksgiving morning which will be the last of the 50 degree days ... according to the extended forecast, we are headed into the 30's at least for the next ten days. If that happens as planned all of the RV-12’s wing components will be primed.

Saturday, November 17, 2012

Sparing Partners

Both the flaperon spars are identical so there is not a left and right to keep track of ... which makes life a little easier in the shop. Both spars needed deburred along the edges of the flanges with a file and then fine tuned with the 1” Scotch-brite wheel on the pneumatic grinder.
           Using the pneumatic grinder with a 1” Scotch-brite wheel to smooth the edges of one of the flaperon spars.

In addition to deburring both long flange edges on each of the A-1203 flaperon spars, each spar requires plenty of extra work in the form of deburring the multitude of lightening holes on each spar. Both spars are now ready for dimpling and priming one day next week.
                                           I won the sparing match with my sparing partners …. both flaperon
                                           spars are completely deburred and now ready for dimpling and primer.

There was a hope of having one of the spars dimpled today but a late morning start coupled with deburring taking longer than expected (it always does) dashed all hopes of dimpling today because I need to take a trip down to the “southern outpost” to winterize … and while there pick up a few tools, propane tank and some items that may come in handy later on the RV-12 project.

Friday, November 16, 2012

Dimpling Flaperon Nose Skins

The decision has been made hold off on assembling the RV-12 wings at this point to prepare the flaperon skins for priming. I was going to wait until later to work on the flaperon spars and skins because the Akzo primer requires temperatures of basically 60 degrees or above and the temperatures are now in the 40’s. However, the paint department is almost out of the Akzo primer so the DOG Aviation research department has been looking at other primer options which will work at lower temperatures and are suitable for the project.

While researching, a visit to the website of a fellow RV-12 builder turned out to be fruitful in that he was using a chromate primer which the manufacturer states can be used in temperatures as low as 40 degrees. The primer comes in quarts, gallons and spray cans.   Perfect … so a call was made to Aircraft Spruce to order a few spray cans of PTI’s zinc chromate primer. Delivery is expected Tuesday and the PTI product will be used to finish off the flaperon spars and skins. If the PTI primer appears to work well, I may use it on the fuselage components since it will be the middle of winter when work begins on it. Hopefully, there will be days like last year when the temperatures pop up into the 40’s so priming can be accomplished successfully.

Work on the six flaperon nose skins began today by first filing the skin edges smooth then using the 1” Scotch-brite wheel to remove the file marks. Fortunately, the edges did not need much edge dressing because the sheer marks were small.
                                         Hand filing the tiny marks left from the sheering process at the factory.
                               Smoothing the edges on one of the flaperon nose skins with a 1” Scotch-brite wheel.

After all six of the flaperon nose skins were smooth, the rivet holes along the outer edges of the skins that will meet with  the flaperon’s spar were dimpled for flush rivets.
Note: I elected not to dimple the rivet holes associated with the nose ribs at this time. Reason being there will be some match drilling of the skins to the nose ribs … it will be easer (and more precise) to dimple those holes after the match drilling is accomplished.
Dimpling a flaperon nose skin for flush rivets using the pneumatic squeezer with 120 degree dimple dies.

Impulse Purchase … while picking up some cargo straps at Harbor Freight noticed there was a service cart on sale. Because of the marathon wing skin dimpling sessions, have forgotten to mention how useful the service cart has been. It is a great addition to the shop and has proven very useful … wish I had purchased one long ago. The single large drawer holds all the specialty tools and the bottom shelf has plenty of room for all the air tools and larger items.  The top shelf is nice to keep those tools and small parts currently in use at arms reach.
                    The service cart from Harbor Freight is proving to be a wise investment. It is actually sturdy,
                    has a good sized drawer which opens and closes nicely, rolls easily and the two front wheels lock.

Monday, November 12, 2012

Wing Skins Primed After Five Daze Of S&M

Wow!! What a week of self abuse at DOG Aviation … done with a painful smile of course.  Yesterday was what will likely prove to be the last warm, mid 60 degree day of the year … so the push was on all last week to prepare all the RV-12’s wing skins for priming to take advantage of the short lived burst of warm air.  The paint department stepped up and painted non-stop all day and into the evening Sunday to ensure the skins for both wings and all the miscellaneous parts were primed while the temperatures were favorable. Spray & Move … spray & move and when you think you should be near done, there is still plenty more to spay & move.

Although successful in getting all the wing skins primed and cured during the warm temperatures, doing that many large parts at once was a logistical nightmare and just crazy. But Mother Nature waits for nobody, so once again I was a man on a mission trying to beat the weather. Oh to be back in southern California where virtually everyday is a good spray day. Sadly, there was not enough time to dimple all of the components for the flaperons, but they are not needed to complete the wings … so they will be prepped and dimpled as to be ready for priming whenever the temperatures hit 60 degrees again. Truthfully, there just would not have been any room to store those parts for drying anyways.

I think my aluminum mistress may have a kinky side … she required suspension bondage during the dimpling process for six of the largest wing skins and again after the skins were primed. Of course, the skins are so large that storing all of them horizontally for drying was simply out of the question. The DOG Aviation procurement department picked up some bungee cords at the nearby Walmart aircraft supply store and hooked them over the rafters and garage door tracks.
                                    The fruit of all the effort … suspended like bats taking a daytime nap, all of the
                                    RV-12’s wing skins drying while hanging from rafters, garage door tracks and drying racks.

Using the C-frame virtually non-stop to beat the aluminum skins into submission (along with myself) while creating thousands of dimples became a painful masochistic ordeal and took its toll on my right arm, neck, back and right elbow in particular. The repetitive process of whacking the C-frame with a mallet virtually non-stop over three long loooooong work sessions got my right arm so sore I was forced to become ambidextrous and finish up the fourth day of dimpling wheeling the mallet with my left arm. What do they say about no pain, no gain … I know! Jan, where’s the bottle of Aleve?

The last five daze have been just that, a daze of pain along with pleasure by way of accomplishment. Feel it prudent to take a few days off to recuperate … perhaps a massage is on the horizon.

Thursday, November 8, 2012

Scrape, Peal, Smooth, Create Craters - Repeat

A late start today has dashed all hope of working on only the right wing skins tomorrow. That said, at least most of the left wing skins remaining will offer good access for the C-frame so it should go faster. The day was spent scraping the the edges of the left wing's skins with a file to smooth out small shear marks ( so far the skins have had rather small shear marks), then pealing off the tenacious blue protective film, followed by smoothing all the edges with the 1 inch Scotch-brite wheel, then beating the skin into submission with the C-frame and creating craters for flush rivets in the process … dimple by hand if necessary any holes where the C-frame couldn’t reach and repeat the process.

Using a piece of PVC pipe to peal the blue film off the skins is not a piece of cake but it makes a tough chore a lot easier. Once the blue film is on the PVC pipe getting it off requires an effort as well.
                 Using a large PVC pipe to help peal the tenacious blue film off the left wing’s inboard bottom skin.

The inboard wing skins along with the doubler skins for the wing walk areas come from Van’s pre-dimpled above and bellow the leading edge. However, I discovered during a test fit that the flush rivets I’m using sit a little proud. Those following the Blog may remember I had an issue early on where the original dimple dies I had purchased did the same thing with the Gesipa rivets I’m using for the RV-12 project. I redimpled those holes using the Avery dimple dies I’ve been using all along and now have a good flush fit.
                        Pre-dimpled leading edge rivets holes from Vans before re-dimpling with the Avery dies
                        to obtain a flush fit for the Gespia flush rivets being used on the RV-12 project.
                            Dimpling the wing walk doubler skin with the C-frame. The pre-dimpled holes from the
                            factory mentioned above are in the row above and bellow the curve for the leading edge.
                             Using the hand rivet puller to dimple one of the holes in the leading edge of the left
                             wing’s center bottom skin where it was best not to use the C-frame.

Wednesday, November 7, 2012

Dimpling Of Wing Skins Begins

Having taken a couple of days away from the shop, it was good to get back to work on the RV-12. All the prep work is finished on the wing’s ribs and they are ready to be riveted onto the spars to form the wing skeletons.

However, after days and days and days of rain and cold weather the forecast for the weekend suggests we may have a significant bump in our temperatures well into the range required for the Akzo primer to cure properly. I feel it would be prudent to take advantage of what will likely be the last couple of 60 degree days of the year and try priming all the wing skins if possible.

Because each wing skin needs dimpled prior to priming, the push is on to complete all the necessary dimpling as quickly as possible. Guess I will need another marathon session or two. Today was spent sorting through the remaining wing components and placing them into piles of left and right wing parts followed by deciphering the drawings to determine which side of the skins and miscellaneous parts will require dimpling. Because the left spar is already out of the box and ready for assembly, the plan is to dimple all of the left wing’s components first before moving on to the right skins. I was able to get one large skin deburred and dimpled today plus a hand full of smaller parts.
                                                               Deburring the left wing’s bottom outboard skin.
Using the C-frame to dimple the left wing’s bottom outboard skin for flush rivets.
Due to the size of the skin, the C-frame could not reach the center row of holes, so quite a few holes had to be hand dimpled using the custom 120 degree dies that have holes drilled in them so they can be used with a nail and the hand rivet puller. Because the lower skins wrap around the leading edge of the wing, all the lower skins have a pre-formed bend in them. In order to dimple the portion that wraps around the wing's leading edge using the C-frame, I decided to suspend the skin from the rafters.
                                  Left wing’s outboard skin suspended so the portion that wraps around the leading
                                  edge could be dimpled with the C-frame without stressing the leading edge bend.
While the wing skin was suspended, it was quite easy to use the custom 120 degree dimple dies to dimple the center row of holes the C-frame could not reach.  Now that I have a system which seems to be working well, I’m hoping I will be able to move through all the remaining skins before Saturday afternoon. The left skins should be completed just not sure if there will be enough time to complete the right skins in time to prime while the temps cooperate.