Tailcone finished! [9.5 hours]

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.

  • tca1
    tca1

    tca1

    Riveting aft deck
  • tca2
    tca2

    tca2

    Fitting top skin
  • tca3
    tca3

    tca3

    Aft deck bolts, brackets fitted
  • tca4
    tca4

    tca4

    Bell crank fitted
  • tca5
    tca5

    tca5

    Preparing to crawl into the tailcone...
  • tca6
    tca6

    tca6

    Resting...
  • tca7
    tca7

    tca7

    Working...
  • tca8
    tca8

    tca8

    Wedged down in the pointy end...
  • tca9
    tca9

    tca9

    Tailcone riveting complete
  • tca10
    tca10

    tca10

    Cleaned up and ready for storage

 

Tail cone riveting ctd. [12.5 hours]

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.

  • tc90
    tc90

    tc90

    Fitting right side skin, preparing for back riveting
  • tc91
    tc91

    tc91

    Right side skin riveted along J stiffeners
  • tc92
    tc92

    tc92

    Barely enough room for squeezer on rudder stiffener AD470AD4 rivets
  • tc93
  • tc94
    tc94

    tc94

    Both sides fitted, J stiffeners back riveted
  • tc96
    tc96

    tc96

    Rosie at work

Riveting tail cone [10.5 hours]

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.

  • tc80
    tc80

    tc80

    Bulkheads and other subassemblies riveted
  • tc81
    tc81

    tc81

    Bellcrank ribs riveted
  • tc84
    tc84

    tc84

    More assemblies
  • tc85
    tc85

    tc85

    Trim mount bracket
  • tc87
    tc87

    tc87

    Trim mount bracket
  • tc82
    tc82

    tc82

    Back riveting bottom skin, stiffeners
  • tc83
    tc83

    tc83

    Missing dimple .... argghhhh!

 

Tail cone de-burring, dimpling and additions [35.5 hours]

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.
  • tc40
    tc40

    tc40

    Wearing out de-burring wheels
  • tc41
    tc41

    tc41

    Pre-drilled hole for tail light wiring
  • tc42
    tc42

    tc42

    Peeling off the blue stuff
  • tc43
    tc43

    tc43

    Dimpling the bottom tail cone skin
  • tc44
    tc44

    tc44

    A pile de-burred parts
  • tc45
    tc45

    tc45

    Dimpling left side tail cone skin
  • tc46
    tc46

    tc46

    Tail cone top skins dimpled
  • tc47
    tc47

    tc47

    Dimpling tail cone J stiffeners
  • tc48
    tc48

    tc48

    Test case - dimpling skin + stiffener together, for F-1006 holes not match drilled until Section 32
  • tc49
    tc49

    tc49

    Dimpling tail cone bulkhead
  • tc50
    tc50

    tc50

    Setting up to drill elevator push rod
  • tc51
    tc51

    tc51

    Drilling #40 elevator push rod
  • tc52
    tc52

    tc52

    Finishing push rod holes with a #30 reamer
  • tc53
    tc53

    tc53

    Initial layout for aft vents, too far forward (interferes with bracket rivets)
  • tc54
    tc54

    tc54

    Hole pattern, #40 holes to establish corners of aft NACA vent slot
  • tc55
    tc55

    tc55

    Drilled holes to get the jig saw blade in
  • tc56
    tc56

    tc56

    My late father's 30+ year old jig saw, with bottom masked up and lubricated (new) metal cutting blade
  • tc57
    tc57

    tc57

    After cutting with jig saw
  • tc58
    tc58

    tc58

    After filing, sanding and scuffing
  • tc59
    tc59

    tc59

    Vent flange area with extra scuffing, ready for pro-seal. This will be treated with an Alodine pen, and left un-primed.
  • tc59a
    tc59a

    tc59a

    Skins being de-greased, ready for etching and priming

 

Started tail cone disassembly [5.5 hours]

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.

  • tc35
    tc35

    tc35

    Deburring top skin
  • tc37
    tc37

    tc37

    Deburring top skin
  • tc36
    tc36

    tc36

    Match drilling rear seat belt anchor into tail cone longeron
  • tc38
    tc38

    tc38

    Drilled 1/4 inch holes each side for SafeAir1 static ports

Aux avionics shelf [2.5 hours]

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.

  • tc30
    tc30

    tc30

    Bracket for Aux avionics shelf
  • tc31
    tc31

    tc31

    Bracket for Aux avionics shelf
  • tc32
    tc32

    tc32

    Aux avionics shelf in place

Working ahead a bit [7.5 hours]

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.

  • tc20
    tc20

    tc20

    Misc. brackets and trim components
  • tc21
    tc21

    tc21

    Bracket for future use
  • tc22
    tc22

    tc22

    Working ahead a bit with battery mount and bell crank supports
  • tc23
    tc23

    tc23

    Brackets and inspection covers fitted to aft of tailcone
  • tc24
    tc24

    tc24

    Brackets and inspection covers fitted to aft of tailcone

Continued tailcone work [16.5 hours]

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.

  • tc10
    tc10

    tc10

    Drilling left side longeron
  • tc11
    tc11

    tc11

    Both sides longeron drilling complete
  • tc12
    tc12

    tc12

    Fitting top skin
  • tc13
    tc13

    tc13

    Fitting top skin
  • tc14
    tc14

    tc14

    Fitting top skins
  • tc15
    tc15

    tc15

    Top skins fitted, match drilled
  • tc16
    tc16

    tc16

    Top skins fitted, match drilled
  • tc17
    tc17

    tc17

    Top skins fitted, match drilled

Started tailcone [17.5 hours]

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…

  • tc1
    tc1

    tc1

    Cutting F-1047 stiffeners
  • tc2
    tc2

    tc2

    Cutting F-1047 stiffeners
  • tc3
    tc3

    tc3

    F-1047 stiffeners
  • tc4
    tc4

    tc4

    Starting tailcone assembly
  • tc5
    tc5

    tc5

    Drilling stiffeners
  • tc6
    tc6

    tc6

    Added right side skin, match drilling stiffeners
  • tc7
    tc7

    tc7

    Right side stiffeners
  • tc8
    tc8

    tc8

    Right side stiffener drilling complete
  • tc9
    tc9

    tc9

    Flipped over, ready to add left side
  • tc9a
    tc9a

    tc9a

    Flipped over, ready to add left side