As I’m sure fellow RV builders know, it’s unwise to say you’ve ‘nearly’ reached a particular build milestone, as invariably you’ll find there are about a thousand steps still to go before you reach it!
We made that mistake with the canopy frame, allowing ourselves to get excited that we were ‘almost’ at the point of being able to start work on the perspex canopy.
Well, the good news is: we’re finally there and we test fitted the perspex canopy today! But it’s taken a while and an awful lot of hard work to get here…
Fitting and drilling the rear window
Back in May whilst I was away on a business trip, J and our friend Bill decided to fit and drill the rear window, which we hoped would take some of the fear out of working with perspex.
We read a lot of horror stories about drilling perspex (mostly about accidentally cracking it, which is terrifying as it’s a huge and expensive piece to have to ship over again…). Thankfully all went OK with the rear window.
Once that was done, we – somewhat naively – assumed it wouldn’t be long before the big guns came out and we were ready to fit the main canopy as well…not quite!
There was a canopy frame to build first, along with a number of mechanisms to make it latch, unlatch and move correctly.
Step 1: Lots of de-burring, washing and priming (note: Van’s instructions have better steps than the ones in this post, you should follow those)
The complexity of this structure and the number of pieces involved is significant, even compared to the myriad of fiddly and drawn-out processes we have already been through in this build, so the preparation stage was lengthy.
Step 2: Riveting together smaller elements (handles, clips etc) which then get attached to the frame structure
This step was an interesting challenge as we were also starting to need to think about aesthetics and ‘user-friendliness’ as these elements will be constantly in view and in use when we have finished the plane.
Several times when riveting these pieces, we not only had to think about what was comfortable or even feasible with the tools we have available, but also what would be easiest to hold or move once it was in place and in use (eg domed rivet heads are more comfortable to hold than shop heads, so we tried to keep them on the outside of any handles where possible).
We paused the building process several times (albeit as planned) to complete the interior painting and cover the visible areas of the primed parts so that the inside of our finished plane isn’t lime green! I’ve got nothing against lime green, by the way…
Step 3: Cleco up the canopy frame structure
This is also quite complex as there are lots of different pieces which need to go together in a specific order, as well as different rivet sizes and styles to contend with throughout, which means alternating the types of cleco during assembly.
The structure gets quite big and unwieldy quite quickly and it’s critical to avoid putting a twist in it, so the order of clecoing and riveting is important. All of this translates into lots of time passing and lots of patience required (although not always present!).
Step 4: Realise that the workbench you built before you knew anything about building things is not flat. Sacrifice the dining table (which is) for a month…
I mentioned before that the canopy frame must not be twisted, so a flat surface is needed for assembly and especially before anything is riveted. The EAA workbenches that we built before we started our project are great and have served us very well, but we built them on an uneven garage floor at a time when we weren’t very good at making things, and they are not up to the task of providing a flat surface to support the canopy frame!
So, as has happened quite a few times, the build migrated into the house as we found that our dining table was pretty perfect for the job (even if it meant losing all or part of it for around a month while we got the frame assembled and riveted).
I’ve said it before and I’ll say it again, it’s really good that we both fly and are both involved in the build, as at least we are equally responsible for (and hopefully therefore tolerant of) random tools, pieces of aluminium and half-finished aircraft parts all over the house!
Step 5: Lots of rivets, some of which are in REALLY awkward places
We thought we’d done the hard part when we had everything assembled and clecoed, but this canopy frame also turned out to involve some of the most difficult riveting we’ve ever done.
The loosely-enforced ‘no air tools in the house’ rule and our general desire to avoid having swarth everywhere went out the window completely as we realised we had to keep using the dining table’s convenient flat surface throughout the whole process. The compressor was set up in the dining room, most of the tools migrated and we had regular attempts to hoover up the aluminium dust to keep it in check (not entirely successfully).
Due to the curve of the frame and the complexity of the inner workings (ribs, flanges and stiffeners galore), some of the rivets had extremely challenging access.
We spent around 6hrs in a single session one Saturday afternoon to get through most of it, the last 2hrs being fuelled by pure stubbornness and refusal to go to bed with it half-finished. Whilst we have come a huge distance in terms of our riveting ability, speed and quality of results, I still found some of these immensely frustrating.
It was impossible to achieve our usual aim of perfection* when contorted upside-down trying to get into a tiny gap with two different angles involved and at least three other pieces impeding my access, and more often than not trying to buck a rivet I couldn’t actually see. There may have been some swearing…
In the end I think we did fine. The structure is strong, the rivets are in spec and it’s perfectly safe, it was just a long and frustrating process to get there and we were less proud of the overall look of it than we’ve been when finishing mammoth riveting tasks in the past.
Even the easily accessible riveting was slow-going as we had to keep switching sides and stopping every few rivets to measure angles and levels in order to avoid putting a twist in the canopy frame. We fluctuated a tiny bit as we progressed, but were well within tolerance throughout and the end result was zero variation (or too little to measure, see below), which we were really proud of.
*Like most amateur builders, we very rarely achieve perfect results, but usually we can at least see how to do so and we aim to get as close as possible. By having this as our goal, we know the plane we end up with will definitely be safe and it will almost certainly look nice as well.
Step 6: Pause and paint, then put it on the fuselage to make yourself feel good…
At this point, we stopped the assembly to paint the visible parts of the canopy frame with the interior grey paint we’ve been using throughout.
Once painted, it had to sit on top of the fuselage just so we could remind ourselves we were nearly done!
Step 7: Install pins, latches and associated opening and closing mechanisms…
As we did with the brake pedals, we painted some of the smaller interior parts red as ‘highlights’ to complement the eventual exterior paint job (which is also going to be red).
There are some small clips and stiffeners to attach to the structure before the canopy pin and latch mechanisms are installed. It’s very clever and so satisfying when it works and you can open and close the latch as we eventually will when getting in and out of our finished plane!
Step 8: Install tip-up mechanism and test
Next we bolted in the gas cylinders and added bushings and other moving parts to allow the canopy to tip up and close down in a controlled way.
This task comprised of 45mins of searching for all the random bits that we had stored in odd places around the workshop (and/or the house) some time ago, and 10mins of actual assembly…!
And it works! The gas cylinders seem really well-balanced for the canopy design – it takes just the right amount of force to move it at different stages of opening and closing.
Very impressed (mostly with Van’s, but a little bit with ourselves that we pulled it off)!
Step 9: First test-fit of the perspex canopy
FINALLY we actually reached the stage of putting the perspex in place. We will need to take it off again before long and this part of the process will no doubt also be lengthy, but it was so satisfying to put it in place, even for a moment.
And it looks AMAZING!
Next we will be securing and drilling the perspex, then it’s our first opportunity to play with some fibreglass…!