Dave’s RV-7A Building Log

Progress has been sporadic lately. The school musical, soccer party and swim meets take priority over the project, as they should.

I found some time to work on mounting the cabin frame. I cut and then filed the ends of the cabin frame to wrap around the mounting brackets. At first, I thought Dan had read the plans wrong. But if you look at where the longeron is at, the cabin frame is supposed to almost touch the top of the longeron at the back. I rounded the bottom edges of the cabin frame quite a bit so it would nest inside the brackets.

I clamped the cabin frame to the fuselage with the brackets. Despite my efforts to the contrary, the cabin frame ended up being a little narrow after riveting. With 6 bolts holding it on each end, I think it will expand enough to work out fine.

I then turned my attention to the support brace between the F-706 bulkhead and the cabin frame. As part of the fix for the cabin frame service bulletin, Van’s shipped a whole new brace. This one is all nicely cut and pre-punched at one end. It’s just a matter of lining up the spacer I made previously with the F-706 and brace. You can drill out 4 of the holes to #30 from the top, but the other 4 require drilling up from the bottom. Only the aft row of holes is drilled to the skin and F-706. The F-706 gusset is in there as well, so this is one extremely sturdy connection. The forward row of holes at the aft end gets drilled only to the brace.

Before drilling everything, I verified the height of the cabin frame. The measurement on the plans of 17-7/8″ is from the top of the longerons to the top of the cabin frame. It’s a little difficult to measure this dimension. I placed a straight edge across the canopy decks, subtracted 1/16″ for the thickness of the decks and then measured from the straight edge to the top of the cabin frame. It was 1/16″ shy, so I added a spacer underneath the bottom of the cabin frame and re-clamped. It was dead-on after that.

I drilled the brace to the F-706 and cabin frame, including the small angle pieces on the sides of the brace (which aren’t mentioned in the instructions). That’s as far as I got for the night.

It’s been a busy week, but I found some time to work on the project tonight.

I found a good idea on Matthew’s site. I pulled out the top skin to verify the location of the cabin frame brackets. Once the cabin frame is installed, it should line up perfectly with the front edge of the skin. I drilled the brackets to the fuselage increasing from #40, #30, #21, #12, and finally 1/4″. I used clamps, clecos, and temporary bolts to hold the thing in place while drilling. It turned out pretty good.

With an AN4 bolt temporarily installed, I figured out how much needed to be trimmed off the outside edge of the bracket in order to be flush with the side of the fuselage. I put the bracket in the vise, and attacked it with the Vixen file. It took a while, but I finally got the brackets trimmed down on both sides.

I rented a Cessna this morning and did a couple of landings at Auburn. I figured it was good to at least land at the airport where I’m buying a hangar. Besides, Boeing Field where I rented the plane had the big runway closed for construction.

With the fuselage almost completely riveted at this point, I took a careful measurement of the fuselage width. Subtracting the thickness of the two angles that secure the cabin frame, the width was 42-7/32″. This is amazingly close to the dimension in the plans of 42-5/32″.

I started the day by priming a few parts, since I needed to prime the angle on the back of the cabin frame.

I started riveting together the cabin frame with the splice plates. (Don’t forget that angle!) I secured the front half of the cabin frame to a flat sheet of particle board and verified the width before starting to rivet the straps. I kept measuring the width several times during the riveting process, because Matthew had warned me that it can shrink. Everything was fine with just the splice plate riveted on. However, while riveting the straps in place the width slowly started to creep inward. I tried clamping it down, but that didn’t help. After I did all of the blind riveting to attach on the aft half, the width ended up being about 42-1/16″. That’s about 5/32″ more narrow that I need it, but I’m hoping it will spread out a bit when I install it. One tip on this part, countersink the holes for the blind rivets slightly deeper. They have a slightly larger head than the solid rivets.

After dinner, I messed around with the attachment angles a bit. I drilled and squeezed the keeper rivets. The plans are not real clear on where the angles should be located on the fuselage fore/aft, but it looks like they should be 7/32″ aft of the foward edge of the top of the 705 bulkhead. I was about to drill them, but decided to leave that major step until I look at it again with fresh eyes.

It feels like it was a very productive weekend. At least I got that crazy cabin frame riveted together!! That thing is a lot of parts and complication for something that is basically just a curved tube.

I finally riveted down most of the canopy deck. I’ve had it clecoed on for a few months, but thought I needed bucking help to rivet it. Most of it is easily squeezable. I had to remove the canopy deck yesterday to do the 705G riveting, and discovered that I had forgotten to countersink the longeron under the forward canopy deck. Doh! I took care of that and primed the countersinks.

I then tackled squeezing the canopy deck rivets. It went amazingly smooth. Looks awesome!

I looked over the instructions planning what I was going to do for the weekend. As part of the service bulletin on the cabin frame attachment, Van’s sent a whole new set of instructions. I’m 3/4 through the fuselage instructions, so I’m not just going to switch over. Not helpful. On top of that, they altered the width or formatting or something. It was impossible to tell what parts had been updated. Really not helpful. It would have been nice if they had put in change bars, a standard feature in Word. I looked at the section on the cabin frame installation, and it had definitely been changed. I cut out that part and taped it on top of my existing instructions.

In order to get an accurate measurement of the fuselage width, I decided I should finish riveting the few things on the fuselage that I’ve been putting off. Tonight I managed to rivet the 705G in place. I was able to squeeze all but the outboard two rivets, which I solo bucked no problem. A couple of the rivets needed to be in between two sizes that I had, so I used the Scotchbrite wheel to grind it down a bit. Only took about 5 seconds per rivet.

Before and after Adele’s final soccer game of the season (0-0 tie), I found time to prep and prime some of the cabin frame parts.

I finally got in a good work session tonight and finished up the cabin frame countersinking. I moved on to deburring it and will hopefully prime it tomorrow in preparation for assembly.

I also worked a little bit on repairing my toy helicopter. This thing is a clever bit of engineering. It’s not anywhere near as maneuverable as the RC helicopters costing hundreds of dollars, but for $70 it’s a heck of a lot of fun. It’s called a Blade Runner. The twin counter-rotating blades make the thing pretty stable. It uses the landing gear as an antenna, and the little wire from the PC board broke. I soldered on a new one. Of course I used some aircraft wire to fix it.

Speaking of wire, I received the basic wiring kit from Stein a few days back. I’ve talked to Stein a few times on the phone, and he’s a heck of a nice guy. His business on the other hand needs some help. My first order was lost. My follow up phone call was ignored. I ordered the kit again directly with Stein (again). One thing was left off the order and some parts were missing. He’s got good stuff at good prices, though.

Another unproductive building day due to a training session for Adele’s swim team, but I got through most of the cabin frame countersinking. I figured out a handy way to secure the parts for countersinking.

I spent most of the evening helping out at Adele’s swim team meet, but spent a little time starting the long process of countersinking the cabin frame.

I finally finished the cabin frame drilling today. I placed the frame carefully against a straight edge and measured the height. Using the band saw I trimmed off just a tiny bit from each leg to get it to the correct height. I took the parts outside for deburring to keep Julie company while she worked on the brick patio.