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.
I finished the rudder assembly to the point where the skins are ready for riveting together. Decided to put the rudder parts on the shelf until I can arrange a TC visit, since once the rudder is assembled there is not a lot of visibility into the interior. In a small mental lapse, I managed to place one of the AN470AD4 rivets in backwards on one of the rudder spar doubler plates (I’ve been following the convention of placing the manufactured head of the rivets on the thinner material).
I think this is a case where I leave it as is. There’s a small risk of making a mess if I drill the rivet out and replace it for purely cosmetic reasons, so this one will simply go into my imperfection database.
Rudder doubler plate, with plate nut for grounding strap, and one rivet backwards.
Back riveted the rudder stiffeners to their respective skins. Assembled the R-1004 halves and rudder horn, and riveted this assembly to the right skin. Instead of following the assembly instructions I should have back riveted the R-1004B half to the rudder skin, then assembled the R-1004A half, rudder horn etc. onto that, because with the R-1004 halves already combined, the aft most rivet to the skin is a complete pain to buck.
Riveted the R-1003 rib halves to their respective skins, and then used pulled rivets for the first time on the project to mount the shear clips onto the stiffeners on the right skin, ready for assembly.
Due to various distractions, assembly of the Vertical Stabilizer has taken a number of days, whenever I could catch an hour here and there.
I decided a while back to include a conduit up to the top nose rib, as many have done before, and a fabricated a doubler plate to support the conduit end connection, with a couple of flush riveted plate nuts to provide possible support for any future fitting that I don’t know about yet, such as an antenna. I also added a plate nut to the rear spar, to provide a grounding point for a braid to the rudder, again because it is easy to do before assembly.
The riveting went OK. I drilled out and replaced a few, which turned out to be easy enough. There are a few rivets on one side of the lower front spar flange that I’m not happy with. I decided to leave the lower rib cleco’d for now so it can be removed, and wait for a TC to come over and review that area.
Once the blue stuff is removed and the exterior skins cleaned up, it is quite hard to take a reasonable picture of the outside because the Alclad is like a mirror, and reflections make the surface look horrible. In actuality, the surfaces are very clean.
Not much progress lately due to various farm and domestic distractions. I did set aside today to do some priming. There were a lot of components for the VS, rudder and HS spar assemblies, and I decided to do them all as one batch, and do the two HS spars and three skins another day (soon). There were a lot of minor setup things to take care of since this is the first time I’ll have done a significant quantity of material. A dip tank for the acid etch that I’d half made, for instance. So the actual work didn’t start until 3 pm, after which it took me 6 hours to degrease, acid etch, spray on EAP-12 and then spray on the PPG primer.
Results were good. I kept it thin for the most part. There was a lot of over spray with so many small parts, and they all jangled around a bit as I moved from piece to piece. A bit of spitting on a few parts, still learning how to best spray on the primer. Some blue bleed through in parts from the EAP-12 which I put on too thick in a few places. I mixed up 200 ml of primer for this job, and due to the small size of most of the parts, much of it wound up on the (plastic) floor of the booth.
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.