The new HS-710 and -714 arrived last week. Trimming and finishing went quickly, and the new parts fit very well with the existing holes match-drilled in the HS-702s. Pre-punched parts are freakin’ great!
Remaining countersinking done on the VS spar doubler
Not much progress in the last week…family stuff took priority, and then work stuff got in the way. I did, however, get the remaining countersinking done on the VS spar doubler.
Following that, I finished all the parts prep work – deburring and edge polishing, then dimpling for the other VS parts. All that remains for the VS before assembly is cleaning, Alodining and priming.
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.
Primer arrives
Lots of things happened in the last week. My primer finally arrived, after only a month’s wait. Super Koropon may be a great primer, but I don’t understand why it takes PRC a month to crate and ship a two-gallon kit.
One thing I didn’t mention in the last couple of weeks is that I messed up the VS spar reinforcement plate while trying to cut lightening holes with a fly-cutter. That’s probably a result of not taking shop classes in high school.
There were some newsgroup debates about whether to cut the holes at all. The argument that makes the most sense to me is that lighter is always better, at least in RVs, and that 8 ounces saved in the tail could mean not having to eventually add pounds of weight in the baggage compartment to fix a CG problem.
Anyway, the new VS spar reinforcement plate arrived on Tuesday, and after using the old part for fly cutter practice, I was able to cut acceptable holes in the new plate.
A side note about pre-punched parts – I was concerned that the new plate would have some minor alignment problems with the spar itself, since I had already match-drilled the two. Well, the new plate clecoed right into place on the spar. Pretty impressive manufacturing tolerances at Van’s, I think.
Match-drilled VS skin
I didn’t waste any disk space on pictures of a match-drilled VS skin and all the individual parts after disassembly, so you’ll have to use your imagination.
Beachcombing time
Not much to report today. I match-drilled all the #30 VS frame holes, then clecoed the skin to the frame. Like I said before – this process is much easier after doing the HS.
It was a little tough to get back in the groove after a weekend on Cape Cod. The water was too cold to do any swimming, but Whits managed to log some beachcombing time.
Start on the vertical stab
We’re still waiting for PRC-DeSoto to deliver the primer we ordered almost a month ago. While horizontal stab construction is on hold, I started the vertical stab. First step is to cleco the rear spar doubler to the spar itself.
I also edge-finished, straightened and fluted all ribs. While doing this for the HS, I wound up with some scratches on the inside radius of some ribs – I think they were from my hand seamer. At any rate, they’re a pain in the butte to polish out, so this time around I covered the seamer faces with thick duct tape, and lined the inside of each rib with Scotch removable masking tape (the blue stuff you see on each rib). Worked great – no scratches.
Next step…clecoing the frame together. This whole process goes much quicker after doing it on the horizontal stabs!
DVD of the day…wait for it…classic Monty Python, including “Upper-Class Twit of the Year” and the Spanish Inquisition sketch.
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.