10-14->18: Side skins / Lower Skin / Tail Spring prep

Moving on to the side skins, these were edge deburred and the edges broken at the top where they go over the 1418B-L&R C Channel Longerons, and also at the bottom where they go over the lower belly skin. At the aft end where they go over the lower aft skin, they required a lot of bend to get them to sit nicely. The side skins, C channel longerons and the side J stiffners were all cleco'd together to check on fit. The upper J stiffners needed to be bent slightly to ensure they didn't contact teh bulkheads - i will prime them and check their fit before riveting (and bend again as necessary).

Deburring side skins...

One side skin on - Major Visual Progress (MVP)

Both skins on. 

An upside down canoe

Cleveland Static Port Holes

I purchased the Cleveland Static Port Kit which required a 1/2" hole in the side skins where the Van's static port rivet would have gone, so i updrilled these using 2 different sized step drills. These will be masked off on the inside when i prime and prosealed in place.

I think they are a really nice fit, and will be much more secure on the inside when i install the static port plumbing than the Van's method (i think). 

Tail Spring Test Fit

Next up was to mount the tailspring mount 1411 bulkhead  - these use AN4 bolts, and i used standard commercial 1/4" nuts, so that i didn't use up the locknuts i have (i don't want to use these for trial fitting and round them out, plus they tend to take off some of the CAD plating when they are installed). Better to just use commercial nuts and make sure i replace them with the proper item at final assembly.

Commercial nuts used to hold the spring in place. 

I found that the fit was very good with the tailspring - with only one thin shim being needed under the forward (bolted) end of the tailspring. To figure out how many shims were needed, i simply bolted it in place with no shims, and slid shims under the aft face (between the tailspring and the 1412 bulkhead).

Shim slid in place to work out how many were needed the opposite bolted end. 

This is where the shim goes to take up any gap between the bulkead and the tailspring.

I had to relieve the 1412 bulkehad quite a bit to get it to clear the weld bead and to sit flush on the tailspring mount (and final fit it later once the keeper rivets were installed).

I ended up reliving most of this on one go, and fine tuned it once i had drilled the keeper rivets. 

I wanted to make sure at this point that the tailspring was mounted parallel with the centerline of the aeroplane, before i drilled the keeper rivets in the spring and before i fit the lower aft skin. To do this i setup a laser along the middle rivet line of the bottom skin and sighted down the tailsping. It was perhaps 1/16" off from centre, and i corrected for this before i drilled the keeper rivets. 

Lower Aft Skin Fit

Next up was to cut the flanges off the lower aft skin according to the plans, and to cut out the hole where the tailspring will poke out. This was almost exactly as per the Van's template on page 10-35. I used the template to mark the cutout, then filed it so that it fit the assembly and was just touching the tailspring. Once this was all fitted up, i cleco'd it all together in almost every hole and drilled the keeper rivets. This set the final position of the tailspring, and allowed me to file the skin some more so it cleared the tailspring all aroung by about 1/16". I think i will end up putting some RTV into this small gap to help keep dirt, water and oil out of the tailcone. I think it came out quite nicely.

The van's template fit perfectly. 

A 1/4" hole was drilled to initially set the curve at the end of the cutout. 

Ititial trial fit - at this stage everything was cleco'd together and the keeper rivets were drilled. 

The final fit..

The final fit

Lots of clecos made sure everything was in place to drill the keeper rivets. 

Once the keeper rivets had been drilled, i fine tuned the aft bulkhead to make sure it cleared the weld bead properly. 

It took quite a bit of filing to clear the weld bead. You can see the marks where it was sitting on the weld bead after the first attempt. Once the final location was set using the keeper rivets, i could do the final filing to sort out the fit. 

C Channel Longeron Adjustments

I noticed when fitting everything up, that the C channel was uncomfortably close to the HS attach bars. I would hate for these to contact each other under load or bending stress when flying etc, so i relieved the c channel a little around this area to increase the clearance to perhaps 3/32"

Alittle too close for comfort here. 

This step also involved the countersinking of the C Channel longeron for a dimpled skin... there were a lot of countersinks!

At this point all side skins, longerons and the lower aft skin are ready to be primed, then we can continue with the construction. At the same time i will re-prime the 1412 bulkhead as this was filed to relieve the weld bead, and also some rivets were countersunk for the keeper rivets. The HS attach bars got some scratches so i will add a little primer to that also when i do the next lot.