Tuesday, May 29, 2018

Wing ribs

Wing ribs are done.  Took a couple months because of the usual excuse (house remodel).  Unfortunately I didn't get many pics.  This chapter was pretty much dominated time-wise by deburring and figuring out where I wanted to run the AoA/Pitot plumbing, power wires, and coax for a Nav antenna.

Here's a stack of 15 ribs, that's enough for 1 wing.

Early on in this chapter I made one of my few mistakes so far.  You have to cut the aft flange off the most outboard ribs, but leave just a little bit of the radius that transitions from the web of the rib to the flange.  Well I tried it with my bandsaw and butchered the hell outta it.  Ordered a new one from Vans and tried the second time with a cutoff wheel on my die grinder.  Worked much better the second time.

Here's looking at a rib attached to the main spar.  Most of them are riveted in the middle, with a AN3 bolt on the outside.  A couple of the outboard ribs don't have the bolt, just rivets.

Here's the mount for the pitot heat controller I put in.  Just some nutplates on one of the ribs close to where I'll put the pitot.  Notice the big hole there too.  That's drilled to 3/4" so a plastic conduit will run thru for wires.

This shows some little wire clips I bought.  I will use these for the Nav antenna coax so it stays separate from the power wires.  Didn't really need them in both wings, but figured it was easy now, extremely little weight penalty and leaves me with more options down the road.

Two last things.  First, priming these was a big job.  My dad and I spent 8 hours scotchbriting them then spraying.  Marathon day.

Also, for AoA/Pitot I used the left wing tooling hole for one tube, but bored another one on the other side of the rib for the other.  I asked Vans if this was ok, they said yup.  Also the plastic bushings they give you (SB437-4) are not the ones you want to use.  They fit the plumbing tube just fine, but the outside diameter requires you to drill an unnecessarily large 7/16" hole.  I found SB375-4 ones on aircraft spruce that only need a 3/8 hole but still fit the tubing just fine

Saturday, March 3, 2018

Wing Spars

Identifying left/right and top/bottom is important on these.  I marked on tape to make it hard to mess up.

As if those huge spars didn't seem long enough, the first thing you do is make them longer.  Match drill four doublers for each spar into the spar extension:

Clamp some J-Channel to the spar flanges and drill a bunch of holes into it.  You don't end up attaching the J-Channel to the spars, this step is just to use the spar as a drill template.  Pay VERY close attention to the plans when they tell you which holes to skip.  The pattern changes a few holes away from the access hole nutplates.  Figure out which holes they are talking about and tape them off.

I skipped around this chapter a bit to get all the pieces that need priming done at once.  The extruded pieces are the wing tiedown points.  They get drilled and tapped to accept eye bolts then match-drilled to the spars.

Here is the spar extension riveted.  First wing rivets!  Building juice optional:

The majority of the work on this chapter is in countersinking all those spar flange holes.  There's a ton of them!

For the nutplate countersinks, the plans specify a maximum size for the top and bottom of the countersunk hole.  I'd say an accurate measurement is mandatory here.  On the tank attach nutplates, my skins weren't quite flush with the spar flange, but it was real close.  Research showed this was OK.

The wing tiedown blocks riveted and bolted:

Aileron actuation brackets on the back side

Wednesday, January 31, 2018

Wing Day

The wings are here!  Van's estimates 8 weeks for wings arrival, and these took the full 8 weeks.  Even with that full wait time, they still didn't send the fuselage spar carrythrough.  Its not needed for the wings but they send it anyway for some reason.  It showed up in its own box about a month later.

The spar box is LONG - about 12'8".  Here's my truck after picking it up at the ABF trucking terminal.

Here they are with the top of the crates popped off

They wrap everything in crazy amounts of packing paper. 

Here's the hardware bag.  Holy motherload of rivets!! 

Time to get to work

Sunday, January 21, 2018

Riveting the tailcone

It took 3 sessions of priming parts to get all the tailcone pieces done.  Then a TON of dimpling.  The side skins have a curve and getting them dimpled with the DRDT-2 was a puzzle but after some time I got it.  Could have used a helper there but I managed.

During final assembly, there's an error in the plans.  The rivet I show here does not go on the AFT lower skin.  It should be the forward skin.

Page 10-25:

I also wondered why the huge hole for the tiedown ring.  Turns out there's a nut on it you can snug up.  Still seems big to me.

Then starts the LARGE task of riveting on the side and bottom skins.  Its a whopper!  Some folks will say you should put both side skins on at the same time to avoid twist.  I didn't think it was an issue since everything is match-drilled and dimpled, if there's a twist its already in.  And also, when I had all the bottom and side skins done the cone would still twist quite a bit with just a small effort.  Not till the rear deck hardware went on did it get rigid against twisting along the longitudinal axis.

Then you put the aft deck on, a few pieces of heavy angle and bolt it all tight.  If you have all 3 yokes for your squeezer, you can get all of the AN470 rivets in the aft deck except for this one (and corresponding one on the other side) with your squeezer.

For the AFT top skin, I learned a trick from Ed's blog.  Thanks Ed, I owe you a beer.  You rivet on the 3 top J-Channel stiffeners before putting that top skin on the plane.  I did a test run to make sure you can get those stiffeners in the frames with it all assembled.  It takes a little persuasion, but sure enough it works.  Saves you a bunch of uncomfortable riveting from inside the tiny tailcone and I find backriveting on the bench makes the best quality rivets.

I riveted in the little hangers I made so adel clamps can be used to fasten the static lines.  I used the middle stiffener, I see others use the left side one.  If I had to do it again, i'd probably do left also.

Sure enough it works.

Similar?  Yes? No?

Here's a small gotcha.  Its in the plans but easy to miss.  Don't dimple the back corner holes of the AFT top skin.  They become fairing attach holes.  The corresponding side skin and longeron holes aren't dimpled/countersunk.

And done!!  There are two more sections in the paperwork, one for assembling the empenage and another for the fiberglass fairings.  I'm going to defer both of those for various reasons.  Bring the wings!