Chapter 11: Canard Installation
With the wing and elevators made, now's the time to install it on the fuselage! It'll be the first thing to make this look like an actual plane. This should be a fairly short chapter, but one that needs lots of measurements done.
Special Tools Needed
- Drill guide for tubing (ACS #12-02937 or equivalent).
- #10 drill bit
- Self-leveling laser line
Tips And Hints
- If you check or canard and find that there is some incidence change across the span, it's been known to happen (happened to me). Averaging out the noise, I had roughly half of a degree of twist. Some have had almost 1 degree of twist. They're flying this way. Moral of the story, don't sweat it.
- I decided to try to split the difference when setting the incidence, but I leaned more towards the leading edge up as down is worse.
- A self leveling laser helps with the alignment.
- In order to make removable alignment tab pins, you will need 3/16 inch ID aluminum tubing, a #10 drill bit, two K1000-3 nutplates and rivets to match, and long AN3 bolts (AN3-40 to AN3-42 depending on your build).
First order of business was to get the fuselage off the rotisserie. I decided to place it on 2 x 4s on top of paint cans rather than saw horses because it wouldn't be too high to work on. Not sure if it was easier this way. Unfortunately, the shop is getting a bit crowded as I didn't have room to maneuver the table around and I just didn't want to bother disconnecting the two parts of the table (read I was being lazy). I used the smart level to get the fuselage longerons level both side to side and front to back. I then laid the canard on top of the fuselage in the cutout area and started making the initial incidence check using the G template.
The self-leveling laser line really helped out with checking for everything to be in alignment. It's a bit hard to see, but you can hopefully make out the line. I used a 1x4 with a line drawn and a hole to place string through to raise the centerline at the back firewall. The clamps and extra board are to stabilize it so it wouldn't bend. The laser line helped establish where this board would go. The string was the only type I could find that had as little stretch in it as possible. It still had a small amount of stretch, so I did my best to measure with the same amount of tension and measured several times. It was during this time that I realized my F28 was parallel to F22. I had a definite larger gap on the passenger side. I'll have to deal with this later.
Unfortunately, as you put stuff together, you start to see the inaccuracies in your build. I was no exception. My lift tabs were definitely not parallel to each other nor were they at the right angle for the fuselage. To correct this and to fix the canard positioning for making it even from the firewall centerpoint, I made a BID pad behind each one. One needed a tapered pad to deal with the tab sticking outward from F22. The other just had a normal BID pad. These were peel plied after placing in the correct spots.
After the BID pads cured, I removed the peel ply and rechecked the incidence. The tab alignment was much better, but not perfect. So to correct the last amount and to ensure the tabs have a flat bearing surface, I wrapped the tabs in mailing tape, then mixed up fox, buttered the area behind each tab, and pressed into place lightly clamping down. I rechecked the incidence, alignment with the centerline and the firewall, and the level of the canard before letting it cure.
I decided to follow other builders and make the alignment pins removable. This seemed like a worthwhile endeavor as it makes canard removal straight forward. You just have to remove the bolts and the canard pulls straight up. In order to do this, you will need the following:
- Aluminum tubing with a 3/16 ID
- A #10 drill bit long enough to drill out the tubing
- AN3-40 bolt (may need longer or shorter depending on how the install comes out)
- K1000-3 nutplate and rivets
- 1/16 inch aluminum plate
While the lift tabs were well stuck and clamped to F22, I decided to make the alignment tabs. Following what several others have done, I chose to use 1/4 birch plywood. I have included a copy of the template for the tabs below. I'm sure the foam is fine, but I'd rather not worry about it. First I cut out the tabs using a template that I made based on the plans. It was made intentionally long in order to allow for easier adjusting. I then checked the fitment of each tab and adjusted. Due to the gap on the passenger side, I cut a second piece with a tapered edge to make up for the excess space. I placed the main tab towards the back to be close to F28 with the extra piece up front to attach to the trailing edge. Once the pieces were trimmed to fit, they were 5 min epoxy attached in place while keeping a 1/16 inch gap between the tab and F28. I used two AN960 washers as spacers.
After the epoxy cured, the surface of the canard was sanded and 5 ply BID was overlapped over the forward face of the tab and onto the canard as directed. I had to allow for longer layup for the passenger side due to the spacer I had to add in. After cure, this was trimmed up. I also found that I had to sand away parts of the outside edges of the tab in order to remain inside the fuselage. Don't know if this is a common problem, but other pictures shows it real close for others to the outside edge, so I did what was needed. They should still be plenty strong especially since they don't carry the main loads in flight anyway.
After that, the #10 hole was re-opened. I rounded the back edge to allow for an easy glass transition on the backside. I then made the 4 ply BID layup to the backside again wrapping onto the canard. All surfaces were sanded to ensure a good bond. Once cured, the was also trimmed and the hole re-opened.
I needed to make my nut plates next. I used 1/16 inch aluminum sheet (already had it from other parts) and cut out two small pieces that would fit within the tabs. I drilled, deburred, and countersunk holes for the rivets and the bolt hole. I put the nutplates at an angle so I could drill a couple of holes for flox to fill and allow a good grip on the pieces. These were then alodined. I then squeezed the rivets into place and had two nutplates ready to install.
To install the nutplates, I sanded the forward face of each alignment tab, made some thick flox, then carefully used a bolt to pull the nutplate onto the surface making sure the flox did not get into or on the bolt. After that, I used flox to fill in around the plate so that 1 ply BID would transition over the nutplate and onto the tab to help secure everything. To lay the BID over the nutplate, I separated the BID strands in the middle to make a hole so it would fit over the nutplate stud. After cure, the BID was trimmed. As a final thing, I painted the side of the exposed wood with epoxy to help encapsulate it and seal.