It took a while but finally I can declare victory for the tail-cone riveting. In the end I back riveted a bit over half of it, but once I decided it was necessary to crawl inside the thing and work it with “Rosie” outside on the rivet gun, we went ahead and completed everything conventionally. The final tailcone statistics include one “oops” rivet, about a dozen drill-outs, with perhaps a few more after a Technical Counsellor visit that I’ve arranged for next week. I managed to do all the inside work without getting stuck or requiring paramedics.
Somewhere in the tail-cone resides the 5,000th rivet driven so far in the project. Only another 15,000+ to go…
As for the small “ding” mark where I dropped a bucking bar (to the left of centre of the only blue plastic bit left, last picture), I’ll get some advice on how best to repair it. It’s easy to access, so drilling for stress relief, dimpling and installing a flush rivet is a likely strategy.
Since the tail-cone will now be in the way while the wings and fuse are built, I made a little trolley on wheels (with brakes!) out of ply from one of the Van’s crates, so I can easily move the thing around.
Continued riveting together the tail cone. It’s taking quite a bit of time, but is going together well. I’ve back riveted most of it but for some parts it was easier to call in “Rosie”.
Not without incident. I always pour a few dozen rivets at a time from the jar into its lid, and use the lid while working. That paid off on no less than three occasions over the last few days after I knocked the lid off the bench and then had to crawl around on the floor picking up rivets. Better a few dozen in the lid than a few thousand from the container! In addition, today for the first time I dropped a tungsten bucking bar onto a skin, and it left a small dent. I swore I would never do this, but now I have. It’s superficial and will be easy to fill in a few years when it comes time to paint, but it’s still annoying to do something like that.
I started riveting the tail cone. Various builders before me seem to have used a back riveting procedure to rivet most of the tail cone, so I thought I’d give that a try. I assembled all of the bulk heads per the plan procedures, but left the top of several bulk heads cleco’d for now, just in case that helps later on. All went well with the bottom skin and stiffeners, until I started riveting the left F-1029 bell crank rib assembly into place. After setting three rivets, I had a look over the remainder and was shocked to find a missing dimple. I checked every part multiple times during and after dimpling, but clearly missed this one. Luckily I only set three rivets before noticing the problem; no choice but to drill them out so I can deal with the missing dimple.
I must be the world’s slowest de-burr-er because it has taken an entire week to pull apart the tail cone, de-burr everything, dimple all the parts and skins as necessary, and do a few other jobs ahead of time. There always seemed to be more things to do. In any case, it’s all done now, ready for priming.
I did take care of some extras along the way:
A doubler for the aft bottom skin, to allow mounting a NAV antenna under the tail. This is a common location, but putting in the doubler after the tail cone is assembled is “hard”. Doing it now, it is easy.
Van’s instructions for installing tail light wiring in OP37-16 has you drill through the entire stack up consisting of the VS spar and F-1012 bulkhead stackup, which includes the F-1012E tie-down bar. I didn’t want to deal with making such a hole straight with a hand drill, or de-burring such a thing, so I pre-drilled through the F-1012 stack-up, slightly over-sized. That only leaves a hole in the VS spar, which will be easy to match up.
Many builders add aft NACA vents to feed vented air into an overhead console. Australian summers are hot, and plenty of vented air is a good thing. I chose to cut the vent holes now rather than after the tail cone is assembled. There’s a bit of a pucker factor involved in smashing holes in a perfectly good skin, and I trialed a few methods on a test piece before settling on an ancient jig saw I had in the workshop. The holes turned out well. I scuffed the area where the vents will be pro-sealed to the inside skin. These will be Alodine’d with a pen after etching, and masked off so they’re not primed.
Since I’ll have to set up the long etch bath to do the F-1047 stiffeners, I went ahead and made up the push rod assembly. That way I can etch the (73 inch) push rod tube while the bath is set up, and prime the inside of the tube per Van’s recommendations.
I’ve started tail cone disassembly. Removed and de-burred the top two skins and the top three J stiffeners. Match drilled the rear seat belt anchors into the longerons. I drilled the 1/4 inch holes required for the SafeAir1 static ports, using a reamer. I’m going to proseal them on, with no rivets. Have to remember to leave a circular area on the inside skin un-primed and well scuffed, for the proseal to adhere to.
I built a temporary support cradle on wheels for the tail cone, mostly out of scrap from one of the Van’s shipping crates (no picture). I’ve grown used to being able to easily move things around in the workshop (everything else is on wheels), and once the tail cone is sitting around here on its own I thought it might as well also be turned into a little vehicle.
That leaves the remainder of the tail cone to disassemble, de-burr, scuff and prime. That will be a long and boring job.
Many builders wind up fitting an auxiliary shelf in the tail cone, for light weight avionics. I’m a fairly large guy and am not looking forward to crawling into the tail cone after it is fitted to the fuselage. As such, I’m trying to prepare as many items as I can now, so that if/when I need them, they’ll be easy to fit.
It takes some messing around to build a bracket for the J stiffener that keeps the shelf straight, but apart from that the shelf itself is simple. I made it out of 0.0625 inch Alclad, with a 1/4 inch flange folded on the front and rear edge. I have no idea what avionics might be fitted to this shelf, but down the road it’ll be a simple matter to lay out items on the shelf, drill lightening holes etc., fit everything and bolt the shelf in place.
I completed fabricating the brackets required to finish the aft section of the tailcone. Before disassembling the tailcone, I decided to work ahead a bit and prepare/fabricate various parts for the empennage attach section, including the trim system. There are a lot of parts to prime for the tail cone, and a few more won’t make any difference. I also added a bracket that Van’s sell, nominally for a Whelan strobe kit, but it can be re-purposed for many different uses. I don’t have specific plans for it at this stage, but it’s easy to fit now so why not.
I’ve continued to assemble the tail-cone over the past few days. Got to the point where the top skins and stiffeners are fitted and match drilled, so the tail-cone is now “torsionally stable”. Still some more brackets to make and various miscellaneous parts to fit before the tail-cone will be ready for disassembly.
Time to start the tailcone! Many hours of de-burring, but the bulk-head parts are “large” so the storage shelves get rapidly emptied, which is a good thing. I used the drop saw to cut the 45 degree angles on the F-1047 J stiffeners. It does a great job but leaves a sharp edge on the “flat” part, which needs to be filed flat again prior to de-burring.
After several days of preparation, I finally started assembly and now have the bottom and right skins cleco’d in place and match drilled to their respective stiffeners. More to come…