Friday, January 31, 2014

Both Longerons Deburred & Rivet Ready

The work session was quite short today but long enough to complete both the RV-12’s longerons. The longerons were removed one at a time so they could be laid on the workbench for deburring. The fuselage was also vacuumed to remove the aluminum shavings from all the match drilling.
Using the deburring tool to deburr the freshly match drilled holes in the right longeron.
Deburring the rivet holes in the left F-1255 longeron using the deburring tool.

After deburring the F-1255- L&R longerons, the F-1234-L&R canopy decks were once again mated with the longerons and secured onto the fuselage assembly with Clecos for riveting.
View of the right longeron’s machine countersinks after reinstalling the longeron and canopy deck onto the fuselage assembly following deburring.

With both of the RV-12’s F-1255 longerons Clecoed in position with the F-1234 canopy decks, the fuselage now looks much the same as it did over a week ago … however, now the F-1255 longerons are match drilled, countersunk for flush rivets and ready for riveting.
Side view of F-1255 longerons and F-1234 canopy deck attached onto the fuselage assembly with Clecos and ready for riveting.
Front view of F-1255 longerons and F-1234 canopy deck attached onto the fuselage assembly with Clecos and ready for riveting.

At this point in time, the instructions would have the builder installing the side skins and riveting everything together. However, some builders have suggested holding off installing the side skins because access is better for installing wiring and the control system. At this point, I’m inclined to leave the skins off for the time being but planning on researching the issue a little more before making a final decision.

Wednesday, January 29, 2014

Machine Countersinking Of Longerons Completed

Because of the flush rivets being utilized on the DOG Aviation RV-12 project, an additional step is required that is normally not necessary on the typical RV-12 … the recently drilled side skin holes in the longerons will require machine countersinking. Now that the F-1270 side skins have been removed decided it would be much easier to just machine countersink the longerons while they were on the fuselage. In an effort to eliminate shrapnel from the countersinking process getting all over the fuselage, a piece of Van’s packing paper was taped under the longeron to deflect the metal onto the shop floor and not inside the fuselage. Decided to start with the right longeron first so the shop would be warmer by the time I got around to starting the left longeron which requires needing to standing by the roll up doors which leak a tremendous amount of cold air.
Beginning the machine countersinking of the right F-1255 longeron. Paper prevents metal flakes from getting in the fuselage.

The countersink bit was set for the depth of the dimples the Cleaveland 120 degree dimple dies create in the side skin material. The countersink cage was adjusted so the depth of the countersinks would allow a dimpled test strip to set flat on the longeron. This ends up being about a click or two deeper than a CS4-4 rivet would normally require being flush. The air to the drill was adjusted WAY down so the countersink bit spun slowly and Boelube was used on the tip of the countersink bit for every hole.  One minor issue came up when attempting to countersink the rivet holes in the area of the F-1234 canopy base … the overhang of the canopy base interfered with the countersink cage preventing it from sitting flat on the longeron, so the canopy bases required being removed from the longerons.
The 120 degree machine countersinking of the right F-1255 longeron's rivet holes almost completed.

As with the right longeron, the shrapnel shield was used and the F-1234-L canopy base was removed so the countersink cage could sit flat on the left longeron.
Beginning the machine countersinking of the F-1255-L longeron.
Almost finished with machine countersinking the rivet holes on the F-1255-L longeron using the countersink cage outfitted with a 120 degree cutting bit.

Now that both longerons have been machine countersunk for flush rivets, the inside edges of all those drilled holes need to be deburred … so that will be first thing on the to do list during the next work session.

Tuesday, January 28, 2014

Left Air Vent Installed - RV-12 Air Conditioning Complete

Taking full advantage of the 5 degree heat wave, a frigid afternoon was spent in the shop finishing off the left F-1270 fuselage skin. The soldering iron was used to remove the blue protective film from along the outer edges of the skin. As with the right side skin, the F-1270-L side skin was temporarily Clecoed high so the top row of rivet holes that were used to match drill the longeron could be deburred and dimpled using the Cleaveland 120 degree dimple dies without the need for a horizontal surface.
Deburring the top row of rivet holes that were used to match drill the F-1255-L longeron.
Using the Cleaveland 120 degree dimple dies to dimple the top row of rivet holes in the F-1270-L fuselage side skin for CS4-4 rivets.
 
Before removing the F-1270-L side skin from the fuselage to make way for countersinking the longerons, the RV-12 air conditioning system was completed. With the temperatures hovering near zero, it is hard to think about the need for air conditioning … but this is the point during the build Van’s has the builder installing the vent doubler/ brackets followed by the installation of the vent door assembly on the F-1270 side skin. This will complete the RV-12’s air conditioning system and will be very much appreciated during hot summer days. But global warming is sooooo last year … thus far this year, it has been one big chill without a hint of warming, global or otherwise whatsoever.
Positioning the F-1096 vent doubler on the F-1270-L side skin.
Riveting the F-1096 vent doubler and F-1086-A&B vent brackets into the F-1270-L fuselage side skin using flush rivets in place of LP4-3 rivets.
 
As done with the right vent assembly, the screw securing the vent door in position is being placed in from the top … should the nut ever come off, the screw holding the vent door will not fall out.
Preparing to slide the vent door assembly through the vent brackets.
Tightening the left vent door mounting screw using an offset screwdriver.
Finished left side air conditioning system.
 
Even though not all that much got accomplished today, all of the work was done in the close quarters between the fuselage and the glass in the roll up doors. Not much heat was making it to that area of the shop and by this time, I was getting quite chilled so decided to pack it in for the day. The next work session will be countersinking the longerons.
 

Monday, January 27, 2014

RV-12’s Air Conditioning System Partially Installed

It was a good day in the office not huge progress, but progress … beginning with the riveting of the 10 nutplates onto the left F-1270 fuselage side skin. Here again the nutplates were installed substituting AN426AD3-3.5 rivets for pop rivets and using the pneumatic squeezer outfitted with a 1 1/2" yoke. The bottom row of nutplates and one side were done with the skin in place … then it was flipped upside down so the remaining nutplates could be riveted easier.
Using the pneumatic rivet squeezer to install one of the 10 nutplates onto the F-1270-L side skin using AN426AD3-3.5 rivets in place of pop rivets.

After finishing up installing the nutplates on the left side skin, the vent doubler and brackets that were Clecoed onto the right F-1270 skin were riveted in place. That was followed by riveting together the two air vent doors that were Clecoed together yesterday. The vent door assemblies were riveted with the pneumatic rivet squeezer using AN426AD3-4 rivets.
Riveting the F-1096 vent doubler onto the right F-1270 fuselage side skin with the pneumatic rivet puller using flush pop rivets in place of LP4-3 rivets.
Using the pneumatic squeezer to rivet one of the vent door assemblies together with AN426AD3-4 rivets.

The plans instruct the builder to install the vent door using an AN525-10R7 screw … which there were issues with. A few months ago while prepping the parts for the air vent assembly, the plans instruct the builder make sure the screw will fit into the slot on the F-1087A&B parts. However they failed to mention to ALSO make sure the screw will fit into the  hole on the F-1086A&B vent brackets. After riveting the brackets for the right air vent in place, discovered the unthreaded shank of the screw would not fit in the hole. A few strokes with a tiny rat tail file fixed the problem … but it would have been a whole lot easier had I checked the fit prior to installing the part as I usually try to do.
Tightening the mounting screw on the air vent door assembly … in summer this vent becomes the RV-12’s air conditioning system.

The plans show the AN525-10R7 screw going in from the bottom with the locknut on top. I don’t like the idea of having a screw mounted that way so installed mine from the top … should the nut ever come off, the screw will not fall out and possibly allow the vent door to blow off the aircraft.  I do understand why Vans shows the screw installed from below is because when the instrument panel base is installed, there is no room for a screwdriver so there is better access from below. However, my 90 degree offset Philips works well here and will also allow access from either inside underneath the instrument panel base or from outside through the air vent. Because future access will not really be an issue, I placed the head of the AN525-10R7 screw in from the top placing my faith in gravity.
Half of the RV-12’s air conditioning system … the right air vent is now completed.

The final task accomplished for the day was to prepare the F-1270R side skin for dimples along the top row of rivet holes which will rivet onto the F-1255R longeron. Using a solder iron, the blue protective film was removed from the outer edges of the side skin, the top row of rivet holes were then deburred and dimpled using the pneumatic squeezer accessorized with the 120 degree Cleaveland dimple dies. The Cleaveland dies will work well for the Van’s CS4-4 flush pop rivets that will go into these rivet holes. Because free horizontal space is nonexistent in the shop, felt it would be best to temporarily raise the F-1270-R skin with Clecos about 6” higher than the longeron to allow dimpling the upper row of rivet holes while the side skin is secured to the fuselage.
Beginning the dimpling along the top row of rivet holes on the F-1270R fuselage side skin using Cleaveland 120 degree dimple dies. Note the skin is raised approximately 6 inches for unobstructed access along the entire edge.
Finishing off the dimpling of the F-1270-R fuselage side skin’s upper row of rivet holes to accommodate the flush rivets being used on the RV-12 project.

Sunday, January 26, 2014

Not All Dimples Are Created Equally

After getting quite a chill from using the snow blower and doing some snow shoveling, by the time I got warmed up again, I just didn’t feel like leaving the warmth of the house … so did not get any assembly done in the shop today. That said, behind the scenes, progress of sorts was made.

I had purposely not dimpled the top row of rivet holes on the F-1270 fuselage side skins so a precise match drilling of the longerons could take place. Now that the longerons have been match drilled, the top row of holes on the F-1270 side skins need to be dimpled to accommodate the flush rivets being used on the DOG Aviation RV-12 project. Also, the newly drilled holes in the F-1255 longerons need machine countersinking to accept the dimples being placed on the side skins.

Before beginning the process of machine countersinking the F-1255 longerons for the flush rivets, a thought occurred to me. I know the CS4-4 flush rivets Van’s uses at some locations on the RV-12 have a slightly smaller head than the Gesipa flush rivets being used thus far. The smaller rivet head should require less countersinking depth thus removing the least amount of metal leaving the longerons stronger. Don’t think this is that a big of an issue here, because all of Van’s aircraft use the same longeron material. Some of them are 200 mph aircraft and can also do aerobatics, however their machine countersunk rivet holes are 3/32" at 100 degrees and not the 1/8" at 120 degree as will be necessary for the RV-12, which obviously requires removing more longeron material to begin with.

Readers who have been following the DOG Aviation Blog from the beginning may remember prior to beginning assembly, it was discovered the dimple dies originally purchased were leaving the Gesipa PolyGrip flush rivets selected for the RV-12 project a little proud. So a switch was made to dimple dies made by Bob Avery. The Gesipa rivets being used have a slightly larger diameter head thus required a slightly deeper dimple and the Avery dimple dies made for a perfect fit … all was good.
Van’s CS4-4 flush rivet on the left and on the right is the Gesipa PolyGrip rivet being used on the RV-12 project. The size difference between the two rivets can easily been seen here.

Time for a little research … the DOG Aviation R&D department used the two pieces that were cut off the aft portion of the F-1270 side skins (.025" thick) for a little test. The Avery 120 degree dimple dies were used to dimple one piece and the Cleaveland Aircraft Tool 120 degree dimple dies were used to dimple the other piece. The results: The Avery dimple dies created dimples .011" deeper than the Cleaveland dimple dies. The Cleaveland dimples measured .053" deep (measured front to back) and the Avery dimples measured .064" deep.

Apparently not all dimple dies are created equally. The smaller head of the Van’s CS4-4 flush rivet fits nicely in the shallower dimple created by the Cleaveland dies … it is ever so slightly proud (but I’m nitpicking). If the Cleaveland dimple dies are used to dimple the top row of holes in the F-1270 side skins, the longerons will not need to be machine countersunk as deeply. … and leaving more metal equates to stronger.
Test using Avery dimple dies and Cleaveland dimple dies … the Cleveland dimple dies (pictured on the top) created dimples that measured .011" (measured front to back) shallower than the Avery dimple dies.

At the end of the day, removing less material from the RV-12’s longerons will yield a stronger longeron. So the decision has been made to use the Van’s CS4-4 flush rivets along the top row of the F-1270 fuselage side skin to F-1255 longeron attachment. The rivet holes along the top row on the side skins will be dimpled using the Cleaveland 120 degree dimple dies. That means the longerons will be machine countersunk to a depth .011" less than would be required if using the Gespia flush rivets. That does not sound like much, but one needs to take into consideration that the machine countersink bit will be creating a 120 degree conical taper in the rivet hole … as such, countersinking deeper ends up removing a lot more material because the hole also gets much wider at the top.

Hopefully, the dimpling and machine countersinking can begin during the next work session after the nutplates and air vent are added onto the left side skin.

Saturday, January 25, 2014

F-1270-R Fuselage Side Skin Busy Work

It was another cold, snowy, nasty day at DOG Aviation today and as the second burner on the heater was slowly beginning to take care of the deep chill in the air, I noticed a pile of snow in the fuselage.  There is a fairly large gap between the roll up door and the door frame which lets in a lot of air (reason for not being worried about the propane heater inside the shop) and lately there have been brutal cold winds and snow. The snow was blowing into the shop and piling up inside the fuselage. Unfortunately, I cleaned it up before having the presence of mind to take a photo. Decided to tape some of Van’s packing paper over the gap, so now any snow that blows in will pile up on the floor.

The initial plan for today’s work session was to remove the F-1270 skins and begin machine countersinking the freshly drilled longerons. However, there are nutplates and the air vent assemblies to install onto the F-1270 skins, plus the aft tab on the skins required being removed. All that got me thinking of the logistics of doing those tasks in a shop that has long since run out of open horizontal space. I decided it would be best to try to accomplish those tasks while the F-1270 side skins are still attached to the fuselage assembly.
 Marking the aft tab on the F-1270-R fuselage side skin for removal.
Using the nibbling tool to remove the aft tab from the F-1270-R fuselage side skin.
F-1270-R skin after removing the aft tab and filing the edge of the skin smooth.

Each F-1270 side skin receives 10 nutplates around the triangular opening … the nutplates require dimpling (the skins were dimpled prior to painting) so 20 nutplates were dimpled.
Using the hand rivet squeezer outfitted with #40 dimple dies to dimple nutplates for flush rivets.

Van’s instructions have the builder install the nutplates using pop rivets. Because the DOG Aviation assembly facility has a 1 1/2" yoke for the pneumatic squeezer, the pop rivets were not used and AN426AD3-3.5 solid rivets were used to install the nutplates.
Placing the nutplates onto the F-1270-R side skin and using Clecos to hold them in position for riveting.
Using the pneumatic squeezer to attach the nutplates onto the F-1270-R fuselage side skin using AN426AD3-3.5 solid rivets.

The nutplate rivets in the upper portion of the triangle would have required trying to use the pneumatic squeezer upside down and setting the rivets blindly … not an easy task. To make the task easier, thought it best to just flip the skin upside down to eliminate the access problem ... worked great!
Finishing up riveting the remaining nutplates while the F-1270-R skin is hanging upside down. Note the snow stopper paper covering the gap between the door and the frame in the background.
Completed riveting of the nutplates onto the F-1270-R skin using AN426AD3-3.5 solid rivets in the place of pop rivets.

Decided to move on and begin preparing the air vents for assembly. The right F-1096 vent doubler and F-1086 brackets were secured onto the F-1270-R side skin with Clecos and readied for riveting. The four parts that make up each of the vent doors were rounded up and Clecoed together. These parts were match drilled prior to painting, so it is necessary to make sure they go together in the same position as drilled. I had used wire to denote the alignment of the pieces.
The four parts that make up one of the vent doors ready for assembly.
Assembling the four pieces that make up the vent door.
Both left and right vent doors Clecoed together and ready for riveting.
The right F-1096 vent doubler and F-1086 brackets secured to the F-1270-R fuselage side skin with Clecos ready for riveting.

The plan is to finish riveting and installing the vent doors during the next work session.

Thursday, January 23, 2014

Match Drilling Of Longerons Completed

Once again braving the 2 degree morning temperatures, a trek was made out to the shop and Mike’s two burner propane heater received another good workout. The day’s goal was to wear three jackets, ignore the inhospitable elements and finish match drilling the very aft end of the left longeron then move on and complete the right longeron before getting too chilled.

The F-1255-R longeron was match drilled to the F-1205B roll bar attach plate during a previous work session so all that was left to do was complete the match drilling of the outside edge of the longeron using the F-1270-R fuselage side skin as the template.
As with the left longeron, the match drilling of the outer edge of the F-1255-R longeron began from the center section forward.
Match drilling the forward most rivet hole in the F-1255-R longeron.

The match drilling of the right longeron was, for the most part, uneventful. There was a small gap between the side skin and a small portion of the bottom of the canopy deck … however, with the aid of a clamp, the small gap was closed and the longeron was drilled. Once the center section forward was match drilled, the aft portion of the longeron was match drilled next.
  Almost done, just a few more holes remain to match drill into the F-1255-R longeron.
Match drilling of the F-1255-R longeron completed.

Now that both F-1255 longerons are finally match drilled, the F-1270 fuselage side skins need to be removed so the aft tab mentioned in the previous post can be trimmed off and all the freshly drilled holes can be deburred. Also there are nutplates to install on the F-1270 skins along with the air vents.

Normally, the longerons would be finished at this point ... but in order to accommodate the flush rivets being used on the DOG Aviation RV-12 project, all of the rivet holes on the sides of both longerons now need to be machine countersunk for the flush rivets being used.

Wednesday, January 22, 2014

Left Longeron Match Drilled

In spite of the latest near zero degree frigid temperatures, match drilling of the left longeron began by aligning the longeron to the roll bar attach plate, clamping it in place and drilling. This secured the longeron in position and the match drilling of the outboard side of the longeron began using the upper row of rivet holes in the F-1270L side skin as a template. Even though the next photo is of the right side of the fuselage, it illustrates the positioning of the longeron in relation to the F-1205B roll bar attach plate … vertex of the longeron is flush with the outside edge of the roll bar attach plate.
Prior to match drilling, the vertex of the longerons need to be made flush with the outer edge of the F-1205B roll bar attach plates.
Match drilling the F-1255L longeron to the F-1205B-L roll bar attach plate.

After the F-1255L longeron was match drilled to the roll bar attach plate, the position of the longeron was adjusted and clamped so the top of the longeron was aligned flush with the top edge of the F-1270L fuselage side skin. Match drilling began from the roll bar attach plate forward.
Using the upper row of rivet holes in the F-1270L fuselage side skin to match drill the F-1255L longeron.

Shortly after the above photo was taken the propane heater shut off and work was suspended to refill all the propane tanks. After running some errands and refilling the propane tanks, heat was restored in the shop and match drilling of the left longeron continued working aft from the roll bar attach plate. The aft portion of the F-1270 fuselage skins have a tab that is used as a template to match drill the aft most six holes in each longeron. This tab will be cut off in line with the aft vertical edge of the F-1270 fuselage skin. The tab is used as a temporary template for drilling holes in the aft most portion of the longeron. These holes will be used later when the tail cone assembly is mated onto the fuselage.
Aft tab on the F-1270 fuselage skins will be removed after match drilling of the longeron is completed. The tab between my fingers will be removed in line with the vertical edge seen under the center clamp.

Tuesday, January 21, 2014

Match Drilling The RV-12’s Longerons Begins

The upper row of holes in the F-1270 fuselage side skins are used as the template for match drilling the rivet holes into the side of the F-1255-L&R longerons. As such, the side skins need to be Clecoed onto the side of the fuselage assembly.
Securing the F-1270-L left fuselage side skin in position on the side of the fuselage assembly with Clecos.

After placing the fuselage’s F-1270 side skins and F-1270A skin stiffeners in position, the three holes pointed out in the photo below were match drilled into the F-1275F corner skin. The F-1270A stiffeners have been added recently to the RV-12 as part of a service bulletin, so the F-1275F corner skin does not have all the necessary holes.
Positioning the F-1270A skin stiffener onto the F-1270 side skin to secure with Clecos.
The three holes above my fingers are the holes that need to be match drilled into the F-1275F corner skins.

I know it is hard to tell from the photo below but the forward end of the right longeron does not have quite enough twist … the inside edge is still a little high. Before match drilling the longerons, thought it best to place the instrument panel bottom onto the forward portion of the longerons to check the fit and get a good visual on how the pieces mate up.
Both F-1270 fuselage side skins in position for match drilling the longerons … note the forward inside edge of right longeron (on left in photo) is still high.

Placing the instrument panel bottom across both longerons confirmed the right longeron still required a little more twist to allow the bottom of the instrument panel to sit flat across the top of the longeron. Using a couple of Crescent wrenches, a little more twist was added to the forward portion of the right longeron and now the panel fits nicely on top of the right longeron. Ended up with a slight bump where the Crescent wrench was, but the overall fit looks very good. Time to move on.
Instrument panel bottom sitting in position straddling the tops of the F-1255 longerons checking fit after right longeron twist was adjusted … overall fit is now flush with the top surface of the longeron.
Final shape of forward end of the right longeron … the left longeron was perfect and now the right longeron looks almost identical.

Bernie happened to stop by and was surprised to see how well the longerons we formed in his basement fit on the fuselage. Both sides are now very symmetrical and I’m now very pleased with the overall fit. Knowing the forward portion of the longerons are correctly positioned for the base of the instrument panel, it was time to begin match drilling the right longeron. Decided to begin by match drilling the holes in the roll bar attach plate because it will lock the aft portion of the longeron in position. The vertex or corner of the longeron needs to be flush with the side of the F-1205B roll bar attach plate. The top of the longeron needs to be flush with the top edge of the F-1270 side skin.
Match drilling the F-1255-R longeron to the roll bar attach plate … this will lock the aft portion of the right longeron in position.