Antenna doublers, A/C condenser doublers etc. [38.5 hours]

I had to take a week off building to do some work. Prior to that, I spent a fair bit of time on the mid fuselage skins making doublers for a pair of UHF antennae, and doublers and mounting points for the A/C condenser. That’s right, this RV-10 is going to carry around an air conditioning system.

I made doublers for a pair of CI-122 UHF antennae, positioning them in the second outboard bay left/right under each side of the rear seat ribs, a commonly used place in the RV-10 world.

Then came the time consuming part. The A/C condenser is mounted in a scoop. The standard attachment method specified by Airflow Systems is to use Rivnuts – because the installation instructions are written for an already completed aircraft. Since I’m slow-building the fuselage, I can take the slow route and use platenuts and doublers. This is quite a bit of extra work, and does turn the bottom skin into a piece of swiss cheese – but the end result is much stronger and cleaner than the rivnuts. All of the doublers and shims weighed in at 408 grams – so I’ve added 0.9 pounds to the airframe.

With this work done, I finished match drilling the skins, disassembled everything, de-burred and dimpled the skins, de-burred, dimpled and/or countersank the mid fuse ribs and spars. The skins and doublers are ready for priming. I don’t really want to prime the large F-1076 skin with my mini-gun, so I’ve ordered a regular spray gun – need one to do the interior painting within a month or two anyway. I’m going to put the skins aside until that arrives, and start on the firewall / forward fuse.

  • f3a
    Match drilling Antenna doubler, inside view with CI-122 cleco'd in place
  • f3b
    CI-122 UHF Antenna in place
  • f3c
    CI-122 UHF Antenna cleco'd in place with doubler
  • f3d
    Establishing centre line on A/C condenser scoop
  • f3e
    Marking out a transparent template
  • f3f
    Cutting out the perspex template
  • f3g
    Checking perspex template fit
  • f3h
    Perspex template taped to skin
  • f3i
    Condenser inlet/outlet holes and doubler
  • f3j
    Trial fit, aft holes done
  • f3k
    Trial fit, with rear doublers match drilled
  • f3l
    Trial fit, with front doublers match drilled
  • f3m
    Two antenna doublers, and full set of condenser doublers, weighs 408 grams, ouch
  • f3n
    Two UHF antenna doublers, and all condenser doublers
  • f3o
    F-1077 skin, dimpling around edges
  • f3p
    F-1077 skin complete, doublers all dimpled and complete
  • f3q
    F-1076 skin ready for de-burring and dimpling
  • f3r
    F-1076 skin deburred and dimpled
  • f3s
    Dimpling mid fuse ribs

Mid fuselage ribs [28.0 hours]

This week I’ve moved on through the infamous section 26 of the build manual, match drilling the outer ribs, rear set and baggage area ribs, de-burring, dimpling, priming and finally riveting them in place to make up the mid fuselage skeleton. This section of the build manual is infamous not only because it misses out several necessary steps that, if not done now, are very difficult to correct later, but also because Van’s have never revised the instructions. Various builders have documented what extra steps to do, I researched this and came up with the following list, to be added to the steps on page 26-5.

  • Dimple the #40 holes in the F1015A outer ribs
  • Dimple the #40 holes in the inter-costal ribs that mate with the F1015A ribs
  • There are three #30 holes in the side skins that are not present in the F1018 ribs. Cleco the F1018 ribs to the side skins now, final drill these holes, and dimple them with a 120 degree dimple set (they will eventually receive CS4-4 rivets).

To do the above, I laid out the F1015A and F1018 ribs, lay the side skin on top and cleco’d the ribs in place. I match drilled all of the #40 holes between them (except for the holes not to be dimpled), and used the skin as a drill guide for the three #30 holes in the F1018 rib. I then de-burred and dimpled the ribs. You need a 3/8″ female 3/32″ dimple die because of how close the holes are to the flange of the rib, and the thickness of the rib making the flange corner quite rounded.

I did look at one builder’s log where he had mistakenly placed the vertical flange of one of the outer ribs on the outside of the corresponding riser, rather than the inside. I recall wondering how anyone could make such a silly mistake, given the obvious detent in the rib. After riveting the left side F1018 outer rib in place, I stood back and looked at it – and couldn’t believe I had just made the same mistake! It turns out to be quite easy to engage the auto-pilot while riveting and overlook something like this. Easy to correct with just three rivet drillouts, but it would have been hard to fix later on when there were more things in the way.

After completing the mid fuse skeleton, I needed to stand it up on something to hang the bottom skins, which overlap the bulkhead by a few inches to overlap the forward spar. I lay the cradle I made for the horizontal stabilizer on its side (not being used right now because the HS is bolted onto the empennage), braced it to some workbench legs, and it made a perfect work position to clamp the mid fuse assembly to while hanging the bottom skins.

Next step is to match drill the bottom skins. While these are in a convenient work position I’ll also drill the necessary holes to mount a couple of antennae, and the A/C condenser.

  • f2a
    Match drilling mid fuse ribs
  • f2b
    Match drilling mid fuse ribs
  • f2c
    Match drilling side ribs
  • f2d
    Match drilling F1015A-L, F1018-L against left side skin prior to dimpling these ribs
  • f2e
    F-1015 ribs require a 3/8" female die for dimpling
  • f2f
    F1015-L, F1018-L ribs laid out
  • f2g
    F1018-L after dimpling
  • f2h
    F1018-R cleco'd under right side skin, ready to match drill three #30 holes
  • f2i
    Mid fuse ribs ready for priming
  • f2j
    Mid fuse ribs primed
  • f2l
    Riveting rear seat ribs
  • f2k
    Incorrect F1018-L position
  • f2m
    Corrected F1018-L position
  • f2p
    Mid fuse assembly skeleton, riveting complete
  • f2q
    Horizontal stab rack, converted into a temporary stand for the mid fuse assembly
  • f2r
    Mid fuse skeleton stacked upright
  • f2s
    Mid fuse rear skin cleco'd on
  • f2t
    Mid fuse bottom skins in cleco'd on
  • f2u
    Fluting F1015A, F1018 ribs - curved to match holes in skin

Finished right flap trailing edge [3.5 hours]

I’ve kept the straight edge I match drilled the right flap leading edge into clamped to the edge of one of the workbenches, to remind me to finish the flap. Today was the day to do that. Same process I’ve described previously – bind the trailing edge with double sided construction tape, then keep drilling 13mm holes out of the straight edge, using a squeezer through the holes to set rivets. Once again it worked a treat, and the right flap trailing edge is perfectly straight. This is also the last trailing edge I have to do – that’s all seven now done and they’re all dead straight. That leaves bottom skins, wiring and fairings for the wings – which I’m putting off for a while so I can make progress on the fuselage.

  • w60a
    Right flap, trailing edge wedge, scuffed and cleaned ready for tape
  • w60b
    Wedges taped in, cleco'd down to previously match drilled straight edge
  • w60c
    After second round of riveting, every second hole done.
  • w60d
    Finished trailing edge - dead straight - and scrap straight edge

Fuselage started! [47.5 hours]

Over the past week I started on the Fuselage. I’ve decided to hold off on closing up the wings for now. I have some primer that is going to expire in a few months, and given what it co$ts the best thing to do is use it up asap. I also need to figure out various system issues over the next month or so because I have to order various things that will take 6 months to get here by boat. Charging ahead with the fuse is the best way to come to terms with what I need to do.

The fuse build starts with various bulkheads, which are all fairly easy to work through. I went ahead with some of the mid fuse ribs, in order to completely fill the spray booth up. After priming everything, it didn’t take too many hours to rivet together the various bulkheads, and finally the inboard and outboard seat ribs.

Next job is to de-burr and match drill a bunch of ribs that join the rear bulkheads up, extending through the rear baggage area.

  • f1a
    Cutting hat stiffeners
  • f1b
    Deburring F1005A bulkhead
  • f1c
    Match drilling F1005A bulkhead
  • f1d
    Inboard and outboard rib assembly parts
  • f1e
    Match drilling inboard rib assemblies
  • f1f
    Match drilling outboard seat rib assemblies and intercostal ribs
  • f1g
    Match drilling seat rib assemblies to spar
  • f1h
    Match drilling flap motor support bracket
  • f1i
    Mid fuselage bulkhead, seat rib parts ready to prime
  • f1j
    Set up for etch and priming
  • f1k
    Weld overrun in landing gear support bracket impinges on spar
  • f1l
    Weld overrun ground down, primed
  • f1m
    Mid fuselage bulkhead parts etc. primed
  • f1n
    Riveting front centre section bulkhead
  • f1o
    Riveting aft front centre section bulkhead
  • f1p
    Riveting aft front centre section bulkhead
  • f1q
    Completed aft centre section bulkhead
  • f1r
    Fuselage bulkhead
  • f1s
    Inboard seat rib parts
  • f1t
    Outboard seat rib parts
  • f1u
    Riveting inboard seat ribs
  • f1v
    Riveting flap motor bracket
  • f1w
    Riveting inboard seat ribs
  • f1x
    Inboard and outboard seat ribs riveted to aft centre fuselage bulkhead
  • f1y
    Flap motor bracket
  • f1z
    Seat ribs, wear strip on aft centre fuselage bulkhead