Started wing assembly [6.5 hours]

After the final small priming job – main spar flanges – I’ve assembled the ribs onto the main spars, ready for riveting. I 3D printed thirty of the custom nylon clips (15 left-hand and 15 right-hand) and fitted these to the ribs. These clips have provision for a 20mm wiring conduit, two smaller holes for either air lines or coaxial cable, together with a slot through which a cable tie can be anchored. I inserted each rib in position and held it in place with the bolts and cleco’s. I’m waiting on some tooling before I drive the main spar rivets, in the meantime there are plenty of other jobs to go on with.

I did look forward in the plans and pulled some parts required for later on. One of these items, the aileron bell-cranks, showed up a problem. There is a brass bush about which the bell-crank pivots, held in place with an AN4-32A bolt. One of the bolts has a slight bend in it, which is enough to make it not go through the brass bushing. Rather than force it or otherwise work around the problem, I’m going to organize a replacement bolt, since this is a fairly important part of the control linkages.

  • w27g
    Preparing main spar for priming flange
  • w27h
    Main spar after priming
  • w27a
    Fitting wiring/air-line clips
  • w27b
    Wiring/air-line clip in place
  • w27c
    Preparing ribs for riveting to main spar
  • w27d
    Ribs ready for riveting to main spar
  • w27e
    Ribs ready for riveting to main spar
  • w27f
    Aileron bell cranks, bushings, and bent AN3-32A bolt


Priming left wing skins [4.5 hours]

Given the workshop space, it’s better logistically if I prime the left wing skins before preparing the right wing skins, so that’s what I did today.

  • w26e
    Scuffed ready for priming
  • w26d
    Spraying EAP-12 surface prep
  • w26b
    Left wing inner skins
  • w26a
    Left wing long skins
  • w26c
    Priming edge of main spar

De-burring / dimpling wing skins [7.5 hours]

I de-burred and dimpled the first pair of wing skins in the last few days – in this case the left bottom skins. I started with a bottom skin pair in case I messed up the scarf joint. To do this joint, I decided to leave all the power tools alone and file it by hand. That was the right approach for me – giving plenty of control over what was going on. It might seem counter-intuitive to file in a direction from the outside in, but with the skin clamped down to a flat surface it works just fine. Tape up the end of the file, and around the area to be taken down, and use light, slow, deliberate strokes with the file.

I used a micrometer to check on the cut depth for each skin at the overlap point, and checked the final result by matching the skins against a scrap piece of 0.032 Alclad.

I had my second clumsy accident of the build, putting a very small ding into the skin with the end of a clamp. It didn’t look like much, but under a magnifier it looked worse, so I drilled it out #40 to take out the stress point(s) and dimpled the hole. It’s on the bottom skin after all, I’ll just fit an ‘A’ rivet to it and live with the fact that it isn’t perfect.

It took me 7.5 hours to do all this work with one pair of wing skins. There are three other pairs left to do.

  • w25a
    De-burring wing skins
  • w25c
    Filing scarf joint
  • w25b
    Filing scarf joint
  • w25d
    Skins after dimpling complete
  • w25e
    Skins after dimpling complete


Priming wing parts [16.0 hours]

I primed all the internal wing parts, across four separate, boring priming sessions.

When I built the spray booth, and the frame for etching “long” parts, I sized them to fit the HS spars, since that is what I had. It turns out I should have made them slightly longer, so that the wing rear spar would fit in. Rather than build an extension on the end of the spray booth, I sprayed these parts outside – which reminded me why I built a spray booth.

  • w23a
    Some wing ribs ready for priming
  • w23b
    Primed wing ribs
  • w23c
    Piles of primed wing parts
  • w23d
    Ready to etch long parts
  • w23e
    Shooting primer in the spray booth
  • w23f
    Priming the wing rear spars - outside
  • w23g
    Wing rear spars
  • w23h
    Long wing parts primed

Outboard assembly fit, prepare for priming [6.5 hours]

I checked the fit of both the left and right outboard leading edge assemblies to their respective main spars, and match drilled the rib-to-spar holes. By doing this step now, I don’t have to do any more drilling through the main spars. I replaced some rivets and generally cleaned up the outboard assemblies. I’m waiting on some parts, and a simple vacuum pump, in order to fix the leaks in the outboard tanks. In the meantime, I’ve set them aside.

I still need to de-burr and prime the skins, but because I have such a large backlog of priming already I’m going to go ahead and prime all the wing internal components, as well as the long sections and spars. To do this I rearranged the workshop into priming mode, ready to start the de-grease/etch/rinse/prep/prime cycle tomorrow.

  • w22a
    Checking outboard leading edge assembly, match drilling to spar
  • w22b
    Workshop set up for priming wing parts.
  • w22c
    Ribs and other wing parts. "Long" wing parts and rear spar will be done separately