Latches and linkages

Next up on the canopy task list…installing the side latch handle, linkage and latch tube. The only tedious part of this process was laying out and cutting holes – very visible holes – in the fuselage side skin to accommodate the latch handle slot and rivets.

Vans includes a template in the plans to lay out and drill the holes, but I decided to measure and lay them out by hand.  It took a little time, but the results were good.

Laying out latch holes

The four larger holes in the middle mark the start and end of two rectangular holes for the canopy latch handle. I used – very carefully – a cutoff wheel in my Dremel tool to start the holes, then finished them with a flat jeweler’s file.

Opening up latch holes

I borrowed an idea from fellow builder Mike Bullock and clamped a piece of scrap angle to the skin as a reference for filing. The holes came out nice and straight…very cool.

Latch assrmbled

Here’s the latch mechanism itself – two pieces of 0.063″ angle sandwiching the latch handle (top) and locking mechanism (bottom).

Drilling the latch

The latch mechanism fit almost perfectly in the slots I cut – only a little adjusting was required on the front hole. I clamped the mechanism in place and match-drilled the angles to lock the whole assembly into place.

Latch clecoed

Here’s the other side with the spiffy yellow latch knob installed. There’s also a very small hole drilled in the wing carrythrough bulkhead which supports a small spring that keeps the locking mechanism pressed against the latch handle.

Fitting latch tube

The latch tube itself is held in place by two Delrin blocks that are match-drilled to the F-705 bulkhead. Fingers on the latch tube engage holes in the bulkhead. There was only one minor problem – the tube was slightly too long, which made it impossible to center the blocks on the F-705 reference holes. A tubing cutter took care of that problem.

Latch tube drilled

I drilled the blocks to #10, and the F-705 holes to #12, to accommodate AN3 bolts that hold the blocks to the bulkhead. Here’s the tube bolted into place, and two parts of the latch linkage in place.

Latch linkage fitted

The only remaining part to be fabricated was the pushrod that connects the latch handle to the latch tube linkage. Nothing too difficult, just a lot of twisting with a 1/4″-28 tap.

Latch linkage with tube

And here’s the final product…everything works smoothly.  Cool.

Starting the canopy

Although I still have to finish up the elevator pushrods and mount the horizontal and vertical stabilizers, I’m moving on to the canopy frame while I decide what to do about Van’s horizontal stabilizer service bulletin. I haven’t decided yet whether to mod my horizontal stabilizer per the bulletin, or just build a new one…

First steps on the canopy are fabricating the alumunum and Delrin spacers that accommodate the canopy hinges.  Nothing too complicated here…

Canopy hinge spacers

Fitting them to the forward subpanel was slightly tricky, since Vans tells you to predrill holes in the spacers that they tell you later to match-drill in place with the subpanel. Fortunately, the hole locations called out in the plans are spot on, so I didn’t have much trouble fitting the spacers.

I didn’t take any pictures of the fitting process, but here’s the finished product on the left side…

Left hinge spacers…and on the right side.

Right hinge spacers

 

Installing the ELT antenna doubler

I’m mounting the ELT antenna on the aft turtledeck skin, and I had to figure out a way to reinforce the skin to comply with the ELT mounting instructions. They call for a round 0.040″ doubler, so that’s what I decided to do.

ELT antenna doubler

There’s not too much else to do here except alodine and rivet it.

Random stuff

I’ve been taking care of a lot of random stuff on the fuselage before starting on the canopy. First up was mounting the brake reservoir..not too difficult except for figuring out how to accommodate the brake connection on the aft bottom.  I traced a hole around it, then used a Unibit to open the hole. After everything was drilled and ready for mounting, I laid a bead of firewall sealant around the connection where it penetrates the firewall.

Brake reservoir

I also installed static lines in the aft fuselage. I was able to do this without crawling into the tailcone, but it was a lot of work.  The static lines are held in place by RTV – this is what Vans’s instructions call for so I hope it works. I also ran the static line forward through the clips I installed when riveting the aft turtledeck skin.

Static line routing

I also ran fuel lines from the fuel selector to the fuselage sides.  Once again, I kinda screwed up here – this should have been done while the wings were temporarily installed.  Not a big deal, though – they can be tweaked when the wings are permanently installed.

Fuel line routing

Here’s the fuselage left side that gets routed to left fuel tank’s inverted pickup. Some builders have managed to do one continuous line from the selector to the tank, but I didn’t want to waste a lot of tubing figuring out how to do that so I’m installing an elbow fitting on the fuselage skin.  There will be another line that routes to the tank from this fitting.

Left side fuel line

Fuel vent lines

Ok, I was wrong – there were a couple of other things to do before the wings come off, and fitting the fuel tank vent lines was one of them. Fortunately, these are some of the easiest lines to fabricate. Sorry, only one picture…so not much to report here.

Fuel tank vent lines

Finishing the tank support brackets

One more task on the tank support brackets – drilling holes that accommodate the bolts that attach the tank support brackets to the tank flanges. I copied an idea from fellow builder Mike Bullock and used a 1/4″ OD drill bushing to drill a #40 pilot hole in the tank angle. The bushing fits snugly in the 1/4″ cutout on the tank support bracket, ensuring that the hole is nicely centered.

Tank support drill bushing

Here’s the bushing clamped in place on the aft side of one tank bracket…

Drill bushing clamped

I then used the #40 hole to center a 1/4″ drill bushing on the front to the bracket, held in place by a piece of 0.25″ aluminum bar.

Larger drill bushing

Here’s the final result…both sides came out pretty nicely.  A 1/4″ bolt slips neatly into place.

Final hole drilledI screwed up a little and didn’t lay out the orientation of the platenut that gets riveted to the tank angle – I’ll have to take care of that when the wings go on for final assembly.

 

Fitting the tank support brackets

I was a little nervous about fitting these two steel brackets that support the forward inboard end of each fuel tank, because I slipped up and had already fitted them to the fuselage before installing the wings.  The brackets are supposed to be clamped to the tank angles – the big D-shaped piece of aluminum on the end of the tank – then match-drilled to the fuse.  I was concerned that they might end up being misaligned, but fortunately that turned out to not be the case.

2014-08-23 17.39.55The right bracket fit almost perfectly after being bent according to plans.  A little adjustment with the vise and hand seamers got it just right…

Left tank support bracket

The left bracket wasn’t quite so easy to fit…I had to tweak it a bit to get it flush with the tank angle, but in the end it came out fine.

Rigging the flaps

The last major task I had to take care of with the wings installed was rigging the flaps. To do that, I temporarily installed the flap motor and flap actuator arm.

Flap motor and actuator

I installed the flaps, and found that the left flap rubbed against the fuselage side skin. The areas outlined in blue are where I had to file off some of the flap skin to eliminate the interference.

Flap interference with skin

The most tricky part was figuring out exactly how much to enlarge the fuselage side skin openings to accommodate the movement of the flap actuator arms as they move the flaps up and down. Here’s my first guess with some rough measurements roughed out from a friend’s RV-7.

Side skin cutout

I also laid out holes on the belly skins and started trimming…

2014-08-22 12.03.05

This was a very iterative process…move the flaps, check for interference, and trim the holes as appropriate.  It took several hours to get the holes for both actuator arms to move freely.

Flap actuator rod

I used my handy Harbor Freight battery booster to run the flap motor…

Flap motor and battery

As I was checking the holes for interference, I was also checking for the proper range of flap motion. Vans says the flaps should go down no more than 45 degrees, so used my digital level to measure the flap angle both at full up and full down – subtracting full up from full down shows slightly less than 45 degrees on both sides – perfect!

Flap rigging

And here’s the end result on the right flap…looks great!

Flaps installed