Lots of progress in the last week and a half…

Lots of progress in the last week and a half…

After riveting a HS-707 nose rib in the left HS left skin, it was time to insert the entire front spar assembly. The plans call for riveting the nose rib in by itself, but it was much easier to keep the skin in place on that nose rib by clecoing in the center and end ribs. Thanks, Mike, for the tip.

I also ended up using one of the MK319-BS monel blind rivets that Van’s calls out as optional for attaching the nose rib. Even with the rib flanges spread a bit before riveting, the forward-most portion of the flange still didn’t lie flush against the skin. So rather than try to buck a rivet while holding the flange in place, I used the MK319-BS. Those of you who either (a) have done this before, or (b) are going for an award at Oshkosh may consider this a cop-out….well, have a nut. The blind rivet worked great, and looks ok too.

And here’s the left skin riveted on, with the exception of the end ribs and rear spar. I’m leaving the structure open until the first visit from my EAA Techincal Counselor. Ken Balch kindly volunteered to be my TC, and I’m really looking forward his first trip to the shop.

One other thing to note…Ellen did a great job with the rivet gun! After only a little practice on some scrap, she was wielding the 3X like she’d done it for a long time.

After repeating the process on the right side, here’s the almost-finished product. It’ll be completed after Ken’s visit…or else I’ll be drilling out a bunch of rivets!

The rear spar clecoed in place. This HS structure is pretty flimsy without the rear spar.

Skin rivets

Not much time spent today, but we did get the first skin rivets in. One small step for the Mighty RV, one giant leap for Dave. I had a bit of a mental block about these rivets. But some practice and mental rehearsal paid off.

Just a few rivets done because it was getting too late to make a lot of noise with the rivet gun. But none of them had to be drilled out. Bonus!

Lots ‘o riveting going on

Lots ‘o riveting going on in the last few days…and drilling out some rivets too.

I had to re-learn all those rivet bucking skills I had forgotten since the SportAir workshop. Ellen caught me in the midst of a hard-to-hit rivet. But the HS front spar is finally finished…

Here are the front and rear spars covered with spiffy yellow Super Koropon primer.

…and here’s everything clecoed together. Next task – practice flush riveting, then start putting the skins on.

HS parts are all alodined and primed

HS parts are all alodined and primed. If you’re desperately interested in the whole process, go here.

Finally…some rivets squeezed! Constructed the horizontal stab rear spar and attached its elevator brackets. I had to drill out a few rivets, but didn’t make too much of a mess.

Here’s one rivet drilled out, and another ready for the punch. Once the rear spar was done, I started re-assembling the front spar in preparation for riveting.

Wrong method

While preparing to countersink the VS spar doubler, I re-read Vans’ instructions on how to countersink. Turns out I used the wrong method on the HS-710 and -714 reinforcement angles – using a male dimple to check countersink depth makes for too deep a cut.

For a hole that will accept a dimpled skin, the current instructions call for countersinking the hole just enough to make a rivet sit flush, then going another 0.005″ (two countersink sink ‘clicks’). Well, mine were a lot deeper than that. According to Gus at Van’s, there are no structural issues since the holes weren’t countersunk all the way through. Riveting the hole could be difficult since the rivet shank will expand in the area between the countersink and the dimple, but the suggestion was to rivet them anyway – four sub-par rivets wouldn’t make that much difference.

Just to be on the safe side, though, I’ve ordered a new -710 and -714. The challenge will be to make the match-drilled holes line up on the other parts drilled in assembly with these two. If I can do that, I’ll use the new parts. If not, I’ll fall back on Vans’ suggestions.

What step did I miss?

Lots of things happened in the last three days. Once the skeleton was done, I prepped the right HS skin, sanding out interior scratches, trimming off blue plastic, and smoothing edges. I started dimpling with the pneumatic squeezer, and then Ellen and I continued with the DRDT-2.

Ok, here’s a quick quiz…what step didn’t I list above? That’s right, I forgot to debur the right HS skin rivet holes until we were about halfway through dimpling. Before doing any more, I called Van’s to see how bad I screwed up. Well, I lucked out – because the cure was simply to sandpaper the male side of the dimples to remove burrs. After reading some newsgroup posts on this problem I considered the possibility of structural problems – cracks, etc. – from dimpling with burrs, but Van’s wasn’t concerned. That’s good enough for me…but this is one mistake I’ll work hard to avoid in the future.

…and I didn’t make the same mistake on the left skin. It’s finished and the HS is done until the Super Koropon primer arrives, which I hope will be in the next week. Can somebody explain to me why it takes PRC-DeSoto a month to ship one 2-gallon kit of epoxy primer?

DVD of the day – ‘The Great Waldo Pepper’. A great, yet underappreciated movie – and in my opinion, some of the best flying scenes ever filmed.

Edge distances are muy bueno

I’ve gone awhile without an update – too much work stuff getting in the way of building! In the last week I finished match-drilling the left horizontal stab, then assembled the right horizontal stab frame and clecoed it to the skin. After prep work on the inboard ribs, I match-drilled them to the front and rear spar, again using a 12″ #30 bit. It worked even better this time than before.

Edge distances are muy bueno – I’m relieved. A screw-up here would mean redoing a lot of work.

After finishing up the right HS match-drilling, I disassembled everything. Had several kinds of fun finishing edges with the scotchbrite wheel, then deburring holes. Following that, dimpled the frame with the pneumatic squeezer – once again, the squeezer is one tool that’s worth the expense. The skins still require edge finishing, deburring and dimpling.

DVD of the day – ‘Monty Python’s Flying Circus, Volume 3’. The ‘Lumberjack Song’ really makes tedious work go faster.

Thanks, Jim!

I finally had some time today for more work. Got the rest of the HS-405 and -702 match-drilled, and clecoed the HS-710 and -714 in preparation for drilling all these parts, plus the HS-404 nose ribs, in assembly. I don’t have an angle drill, and was in a quandry about how best to drill these parts. Even though I measured everything precisely, I was also concerned about having the proper edge distance on all these parts when drilled together. Thanks to some advice from Jim Smith, I managed to get the job done with a 12-inch #30 bit – thanks, Jim!

Drilling is done – and the edge distances look ok. Closest margin is the HS-710 to -405 hole, where the edge distance is just slightly over 1/4″ from the hole center to the edge. The technique I used to lay out the center HS-404 and -405 holes seems to have worked well.

The goal for tomorrow is to finish match-drilling the entire HS left side, then fit the right HS frame to its skin.

Thumbs-up from Van’s

Not much progress recently, a rather tough weekend around the house. Before I finished up the HS left side, I wanted to make sure that the HS-702 tab seen here – left with a smaller edge radius where the excess flange radius was removed – wasn’t too sharp. I emailed Van’s with some pictures, and they gave me the thumbs-up.

One tricky area I encountered was how to drill the HS-405 front flange, and trim the HS-404 aft flange, so that when the two are drilled together all holes have the proper edge distance. Based on newsgroup emails, this area has been a problem for others as well. So, I cut two strips of scrap 0.032″ aluminum and clamped them to the -404 and -405, as a sort of simulated HS skin. I marked the HS-404 flange edges on the -405 and used those marks, plus a little margin for error, to lay out the two center #40 holes called for in the plans. If you use this approach, be sure to pull the -404’s flange tight against the -405 after they are clamped together.