Cut Front of Canopy

I got out in the garage before work this morning because it’s the only time that I can work on the canopy during the week.  The cutting process is really loud, so I can’t do it in the evenings after the kids go to bed.

Anyway, I cut along the line I laid out yesterday and put the canopy back on the fuselage.  The fit was pretty good right off the bat.  The sides also pulled in quite a bit closer just due to this cut.

The center still has about a 1/8″ gap.

And there’s about a 1/16″ gap on each side.

Marked Forward Canopy Cut

I only had a few minutes to work on the plane tonight, but I cleaned up the baffle parts and moved the canopy back to the workbench.  I wanted to cut the bulk of the material off of the front of the canopy, but I haven’t seen anyone come up with a good way to ensure the left and right sides are approximately uniformly cut.  What I ended up doing was taping a piece of string to the top of the canopy along the centerline near the rear.

With some tape in the center at the bottom of the apex of the curve, I used the string to determine how far that was from the taped point.

I then swept that string along the canopy to define the position of the tape.  Here’s approximately the midpoint of one side.

And here’s where the curve intersects the side.  Using this technique, it’s easy to get each side within 1/8″ or so which is more than symmetrical enough.

After using narrow tape to follow the curve, I used wide tape to seal up the gaps in the plastic covering.  It’s too late to cut this tonight, so I’ll do this cut next time.  This will remove the bulk of the flattened flange on the front of the canopy.  There will still be a small radius along this cut line that will need to be removed, but I want to sneak up on the proper fit instead of risking cutting too much.

Started Baffling

My buddy John Soward from KY was in town over the weekend, so we spent a little time working on the plane.  The canopy wasn’t a very good project for two people to work on, so instead we started on the engine baffling.  These are a few of the many pieces that form the baffles that fit on the engine to direct cooling air down through the cylinders.  We basically only made it through the first couple of pages of plans.  It’s easy to see that the baffles will be quite time-consuming.  There are lots of pieces to fit together and tons of nooks and crannies to debur.

Placed Canopy on the Fuselage

I started prepping the fuselage to receive the canopy.  First up was to cleco all of the skins back on.  Next, I put some masking tape over all of the places the canopy could touch to prevent scratching it.  Next, I marked a centerline down the cabin frame.  This will be the eventual split point between the forward canopy and the rear window.

I also taped up the ears on the canopy frame skin to prevent them from scratching up the inside of the canopy.

Finally, I finished cutting all four sides of the canopy, smoothed out the edges, and then placed the canopy on the fuselage.  This looks so fucking cool!  The edge finishing technique I’m using is to clean up the rough cut marks with the vixen file and then sand with 80 grit sandpaper to smooth things out.  I tried breaking a piece of the scrap without edge finishing, and it takes a surprising amount of force, so I’m confident that edge finishing to this degree is more than sufficient.  The shop was between 75º and 80º though, so that definitely helps keep the plexiglas soft.

Started Cutting Canopy

Another RV-7 builder from Paris stopped by tonight and we chatted RV’s for awhile.  It was good to finally meet him as we’ve only exchanged emails up to this point (hi Frédéric!).  After he left, I rearranged the workbenches and pulled down the canopy.  I forgot to take a picture of it, but I then drew a centerline down the canopy to use as a reference point.

First up is to trim off all of the clamping marks on the edges.  I started with the front edge by cutting back the plastic and taping a cut line with some masking tape.

Here’s a closeup of the clamping flange and taped cut line.

It probably took five minutes to cut off the flange.  I’m using the cutoff wheel that Van’s ships with the finish kit.  I’ve installed it on my 90º angle die grinder which helps keep it aligned with the cut line.

I’m covered in fine plastic snow.  I’m not looking forward to all of the cutting that I’ll need to do on this canopy.

Riveted Canopy Frame Sides

I primed all of the mating surfaces and then clecoed the canopy frame back together.  I then clamped the frame back on the fuselage to ensure everything was aligned properly since clecoed joints have a little bit of flex.

I had to use my stubby clecoes to cleco the wedges in place.

I then riveted the splice plates in place.  I had to pull the frame off to reach the rivets on the bottom flange.

Here’s the inside of the joint.

Fabricated Canopy Frame Wedges

Because of the angle the side frames meet the forward canopy weldment, there is a gap between the bottom flange and the splice plate flange.  To fill this, you have to fabricate a wedge out of aluminum.  This took probably one hour to make two of these, but it wasn’t as bad as other builders made it out to be.  The plans specify that it should be 5/32″ thick at the forward end, but fortunately my gap was only 1/8″, so I could use some scrap I already had on hand.  The scrap already had a radius on one edge that tucked nicely into the radius on the bottom flange of the forward weldment.

After fitting the wedges, I laid out and drilled four holes along the bottom flange.

Finally, I deburred all of the canopy frame components.  Next up is to countersink a bunch of the rivet holes and then start riveting this puppy together.  After that, it’s time to start on the canopy itself.  I was really hoping to get the canopy cutting done during August while it’s still pretty warm, but it looks like it’s going to stretch into September.

Worked on Canopy Frame

I finally got a long day on the project for the first time in a while.  I got started by making some 7/8″ and 1/8″ spacers.  I used some blue tape to make the wood spacers exactly 0.875″ thick.  The aluminum bar was already 0.125″ thick.

The flanges of the canopy channel need to be bend to 92.5º (they come from the factory at about 88º).

Bending the flanges of the channels severely warps them.  I had to flute them to get them flat again.

Here’s a closeup of some of the flutes.  Fluting this 0.063″ thick channel is tough.  My hand is aching from this.

I laid out the holes for the splice plate that will join the two canopy channels.  I should have read a few of the builder’s logs a little closer.  The outer holes on the center row end up too close to the tooling holes in the channels.  If you haven’t already drilled the splice place, you probably want to move those holes 1/4″ up.

I drilled the splice plate to one of the two channels.

There is a sharp bend in the canopy weldment.  A few squeezes with the hand squeezer smoothes out the curve.

Next up, I laid out and drilled the holes in the two forward splice plates.  These join the canopy frame sides to the forward weldment.

The splice plate sits immediately  on the other side of this joint.

Here are the side channels clamped down to the 1/8″ spacers.  You can also see the splice plate clamped to the side channel and forward weldment.

The aft end of the side channels are also clamped down on top of the 1/8″ spacer with the rear angle flush against the channel.

The side channels need to be positioned so that the 0.032″ thick canopy skirt will be flush with the side skins.  Here I’m using a piece of scrap to make sure the side frames are positioned correctly.

After everything was finally positioned, the aft end of the side frame can be drilled to the canopy channels.

The forward splice plates were then drilled to the side channels and forward weldment.  After drilling these, I removed all of the clecoes and disassembled all of the canopy frame components.

Fabricated ADAHRS Mount

I decided to take a break from the canopy and fabricate the ADAHRS mount for the Dynon SkyView ADAHRS box.  I looked at several builder’s sites about how other people have done this and settled on a U shaped piece hanging between the center rib and left stringer.  I decided to add some bends along the edges though to stiffen the structure.  It’s approximately level in both axes right now, but I need to fine tune it slightly before drilling the holes though the rib and stringer.

I made the box deep enough that I could put two ADAHRS boxes (stacked vertically) in here if I decide to do that.

Finished Forward Canopy Frame

I finished the fit of the forward canopy frame to the forward skin.

I ended up with about 0.032″ along the entire joint.  I did end up having to put a 0.016″ spacer under the forward channel of the canopy frame to lift the skin up a little bit.  Otherwise, the front edge of the canopy frame skin was pushed up by the subpanel a bit and the front edge of the canopy skin would catch on the aft edge of the forward skin when I tried to raise the canopy.  You can also see here that I installed a bunch of clecos from the inside to give me a little more room to open the frame.  These still stick up too much to allow the frame to open fully though.

This is about all I can raise the canopy before it interferes with the clecos, but it’s enough to ensure everything moves smoothly.  Beyond this point, there would not be any interference anyway.