Monthly Archives: December 2014

Today I riveted the HS front and rear spar assemblies. Straightforward but I had to chase out a few holes where primer had built up to the point where rivets no longer fitted easily. I also ran into a couple of minor issues with the front spar. These were:

• The six longest rivets, which go through the lower HS-1013 spar cap, the HS-1002 spar, the HS-1007 doubler, and the HS-1008 brackets, are called out in the plans as AD470AD4-10’s. I should have checked the rivet length and didn’t. This size is too small, and the shop head is both too small in diameter and too small in height. There are no gaps between the surfaces, so this seems like a case as described in page 5-4 of the construction manual, where Van’s states “… we have chosen to use a rivet that may seem too short in some places, but will do the job adequately”. Still, this is a mounting bracket for the horizontal stabilizer, which seems like an important structural component. For the other five rivet positions, I stole some AD470AD4-11’s from the wing kit, shortened them very slightly with a rivet cutter to the correct length, and squeezed them into place. The shop head for these rivets was excellent and well within spec. The -10 rivet which is out of spec, I’ll check with Van’s about. I’d rather not drill out such a long rivet from an important structural area if I can get out of it.
• I don’t have a suitable squeezer cup set for the centre row of rivets on the mounting brackets, the manufactured head is too close to the spar caps for my cups. Options here are to (a) reverse the rivet direction, (b) buck the rivets, or (c) get a cup set that doesn’t impinge on the spar caps. There’s a fair number of work hours ahead before I’ll be ready to close up the horizontal spar, so I’ve ordered a suitable cup set. If it doesn’t arrive in time, I’ll simply buck the rivets.

Looking ahead at the ribs, I’ve noted an inconsistency between the instructions, which call for making an oval hole in two of the HS-905 ribs, and the ribs themselves, which have lightening holes that overlap the hole position. I’ve sent a not off to Van’s requesting clarification on this, looks like I don’t have to change anything.

Finished HS front spar components.

There’s a lot more work in the front spar preparation, compared with the rear spar assembly.

Cut and deburred the HS-1013 spar caps. Deburred the HS-1002 front spar. Match drilled #30 from the spar web to the spar caps, and deburred. Match drilled #40 from the spar flange to the spar caps, and deburred. Deburred the HS-1007 doubler.

Made the HS-1008 right and left brackets. Van’s only gives you enough material to do this once, so I spent a fair bit of time to make sure I didn’t mess them up, being so far freight-wise from Oregon. A milling machine would have been handy, but I don’t have one so I decided to use the compound saw to do the cuts. I used a bit of cheesy hardware store aluminium angle to verify the saw calibration and setting of the angles, before finally doing a couple of trial cuts on the real material, and then the real cut for the HS-1008R piece. After that I changed the saw around and cut the HS-1008L piece, and they matched up well. Clean up was easy because the Aluminium blade cut is quite clean to start with. Fiddled around with the drill to get the holes accurately positioned. Don’t be fooled by the cross slide vice in the picture(s), it is a piece of cheap Chinese rubbish and barely worth the trouble. The HS-1008 parts cleaned up well.

I used the same 2 inch Aluminium angle that I have prepared for the rudder trailing edge assembly to clamp the HS-1008 brackets to while match drilling from the spar assembly. Not done yet but the front spar assembly is close to being ready, all that remains is match drilling the rest of the #30 holes between the spar and doubler, and a few countersinks in the doubler.