It took quite a few days to grind through the top skin riveting of the first wing, which for random reasons is the right wing. There’s a lot of opinions out there about the “best” way to rivet top wing skins. Some claim back riveting is the best method by far, others claim the crooked back riveting tools are impossible to use and results with conventional riveting/bucking are good. I decided to give back riveting a go and it worked out well, but it requires two of us and after an hour of pressing that large/heavy back rivet bar onto the skins we’re ready for a break. As a result the work was spread out across a number of days, with just 2 – 3 one hour sessions each day. It’s hard to take meaningful photos due to light reflections playing tricks, but I tried my best.
After completion I went back and inspected every rivet. There were a couple already marked – I tend to leave any problem rivets to the end. The final tally was four drill outs, and seven rivets that required a few more taps because they were under-set.
I’m going to go ahead and fit the gap fairings to the right wing, because they’re easy to do and we’re going to take a break for a few days before starting on the top skin of the left wing.
After all the preparation work, yesterday and today I finally started riveting the wings, beginning with the left wing front and rear spar to ribs riveting. I was able to squeeze every rivet on the front spar using the “monster yoke”. For the rear spar – which took a lot longer – I used a standard 4 inch yoke with various die arrangements, except for the three rivets on the inside flange of the Aileron bracket, which I drove using a double offset rivet set.
After riveting was complete, I cleco’d on the top stiffeners, inboard wing walk doublers and both wing skins. Everything matched up perfectly, which seems to have vindicated (so far) my decision to do all of the wing component preparation and priming before riveting.
I put the left wing assembly back on the wing rack, and will now repeat the dose to bring the right wing up to the same level.
Some time ago I wondered why it was not possible to get a larger longeron yoke for the pneumatic squeezer. Out of interest I sketched up what would be required to do the front flange of the wing ribs (there are no doubt many other uses), and had a real live aerospace engineer (my son) draw it up and do a stress analysis. It all looked OK so I had one fabricated on what turned out to be a very slow schedule. The yoke is made from 4140 steel and hardened with a heat treatment, just like the ones you buy. There was a bit of concern about the heat treatment process distorting the part out of alignment, but that turned out to be a non issue. I picked it up today and after a bit of fine tuning all the pieces fitted together as they should.
The yoke is sized to be able to reach over the largest part of the RV-10 spar down into the middle rivet of any rib. There are extension pieces that can be plugged in after the yoke is in position, as shown in the pictures. I tried it out today on a couple of rivets, and after a bit of adjustment it worked really well. The displacement (the amount that the yoke “stretches” under pressure) is quite a bit more than the conventional smaller yokes, and that takes a bit of getting used to. I set just a few rivets, and verified that they can be repeat-ably set to perfection.
Tomorrow I’ll go ahead and rivet all the ribs, as well as the tie-down brackets etc. to the wing spars.
I riveted the Aileron nose sections, and they both went together OK. I’d been waiting on some 120 degree dimple die; these arrived and I was able to dimple the inner and outer rib halves where required and also rivet these down onto the skins. At this stage the Ailerons are ready to complete, but I’m going to hold off riveting the skins on until I finish the wings and flaps, so that I can trial fit the cleco’d ailerons and verify there is no twist.
Today I scuffed, degreased, etched and primed all of the aileron parts. This should have been a straightforward job, and it was until the compressor failed when I was half way through spraying on the EAP-12. A solenoid valve on the output of motor #3 (of 4) blew up, tripping the breaker for that motor and causing a significant leak for the entire compressor. This in turn made the remaining three motors run “flat out” trying to make up for the leak. I hurried through the rest of the EAP-12 application with the compressor in this condition, in order to at least get all the parts “sealed”. Once this is done, the PPG spec says I have up to 72 hours to apply the primer. I’d already made up a pot of primer though, so if I didn’t want to waste it I had a remaining pot life of 4 hours to work out what to do.
It was very hot in the workshop mid afternoon when this happened, which could have contributed to the failure. I used a piece of rubber, some gorilla tape, and a C clamp to temporarily block up the leak (or most of it), and turned the remaining three motors back on. I waited a few hours until the ambient temperature dropped, and sprayed the primer. The three motors alone were on 100% of the time, which is not good, so I wound up the spray rate in order to complete the job quickly. This meant I didn’t achieve the usual extremely light coat on everything, so I’ve probably added a few grams of weight to the ailerons, too bad about that.
Normally an un-primed strip is left on the aileron skin trailing edges for pro-seal. I’m not using pro-seal on the trailing edge, I found on the rudder and elevators that the 3M F9460PC construction tape adhered just fine to a slightly scuffed primed surface, hence there is no un-primed strip in the attached photos.
I touched up a couple of wing parts while I was at it. Replacement solenoid valves are cheap from China, but will take a few weeks to get here, so tomorrow I’ll seal up the leak properly; running on less than four motors will be fine for normal construction and assembly work.
Continuing with the ailerons, I assembled the right aileron nose section and match drilled the counterbalance arm. The next step in aileron construction is the character building task of cutting thirty two stiffeners out of eight pieces of angle stock. I thought of constructing some sort of jig to use the drop saw for these cuts, but decided against doing so because the material is thin and the parts are very small – I’d have to make a very secure jig, the time isn’t worth it.
Therefore I cut the stiffeners using my amazingly dangerous 1950’s era band saw and trimmed them to final shape with a vixen file. That’s the character building part. It takes 25 minutes to mark out and cut one piece of the angle stock, clean each of the four stiffener parts up with a file, and finally de-burr. So, about four hours for the lot.
Still waiting on some tooling before I proceed with wing box section riveting, and waiting on some small amounts of proseal before fixing the auxiliary fuel tank leaks, so with all that on hold I’ve started the Ailerons.
These are fairly straightforward, a bit like the rudder. The counterbalance is a long section of stainless steel tube. After looking forward to doing some mindless filing for a while, I immediately ran into problems because I was missing some parts. After a fair bit of head scratching I decided the only problem I had was the wrong drawings. The print set that came with my kit was marked “Revision 0” and dated 24 July ’14. The parts I had matched the drawings on the CD distribution, which were marked “Revision 1” and dated 23 Feb ’12. What I think has happened is:
The date on my print set drawings is wrong
In 2012, after changing the Aileron design for the RV-14, Van’s decided to update the RV-10 drawings with the same design (since the RV-14 and RV-10 Ailerons are identical), but somehow this update didn’t make it into my print set.
My parts correspond to the updated design.
With that out of the way, I prepared most of the internal parts – same old filing, de-burring, match drilling, countersinking stuff. I got to the point where I’ve fitted the counterbalance arm into the left Aileron nose assembly. Tomorrow I’ll do the same with the right, and get on with the rear assemblies.