Ch 12.1: Canard Mounting

Mounting the canard to the fuselage - Alignment Pins

Yay!...I get to add the first flying surface to the fuselage.  I guess technically it would be the second since I've already fabricated the main gear fairings, which are also airfoils, but this one is more exciting.

Editorial Note:  I know some people following this don't know one part from the next and it's sometimes hard to tell what's going on in my pictures.  So, going forward, I'll try to include a small pic like the one to the right that highlights the part I'm talking about.  Hope that helps.



The canard, like the wings, are designed to be removable.  This is so that you can get to areas under it for maintenance, remove it for any needed work on the canard itself, or transport the airplane.  It's basically held on by 2 bolts.  In my case 4, but technically the upper two are really just alignment pins.  If you're unfamiliar with airplanes you're probably thinking...really! just two bolts?  Yes, and you'd be surprised how few bolts are holding the wings on most all small aircraft.  In aviation slang, these are typically called the "Jesus" bolts of the airplane.  You can guess why.

It must be aligned

Drilling 5/16" hold through the
longeron doubler.  Note the drill block
to help keep things straight.

Note...I'm modifying the plans a bit here.  The first step in the plans was to drill holes part way into the longeron doubler lengthwise and 90 degrees to F28.  In these holes would normally go a permanently installed bolt with the head cut off. The head end of the bolt would stick out forward and act as an alignment pin.  These pins fix the canard at the correct pitch angle or "angle of incidence" for proper flight characteristics.  It will become more clear how in later pics.

In my case, I'm implementing a common deviation which replaces the permanent pin with a removable bolt that runs all the way through the doubler.  Basic directions for this modification can be found in the Cozy FAQs under chapter 12.

Basically, a bolt will come from behind F28 forward through a tube and screw into a nut plate attached to the alignment pin tabs fab'd onto the canard.  The advantage of this is mostly for maintenance.  When you remove the canard using the plans method, you have to pull it forward and away from the pins before it can be lifted out.  Some builders have reported this to be a bit tedious.  Using the bolts makes it possible to just remove the bolts (pins) all together and then the canard will come straight up, simplifying it's removal.

Tube before cutting to size showing
it is perpendicular to the bulkhead

The only initial difference between this and the plans version is that you'll drill the hole all the way through and a bit larger to accommodate a 5/16" tube that will be used to house the AN3 bolt.  Based on some archive research, I used a 5/16" OD x .058" wall 4130 steel tube.  Could you use an aluminum tube?...I presume so but like a lemming, I just followed what someone else had done.  Another option found in the archives was to use a 5/16" OD x .065" thick wall and drill it out to .189 (#12 bit) for a better fit.  I test fit my bolts to the tubes and due to variance in the bolt shafts or the tubes themselves, they fit perfect, no slop.  Since I had already purchased them, I pressed ahead.

Alignment tube from the rear
temporarily installed for fit.

First I drilled a pilot hole before drilling the full size 5/16" hole for the tubing.  Note I used a dill block (available at Aircraft Spruce) clamped to the F28 bulkhead to ensure a straight hole.  You can see from the pic at the left that the hole goes 90 degrees to the front F28 bulkhead and not directly along the longeron which bends outward.  The bolts have to stick out straight forward.  The hole will exit the interior side of the doubler aft of F28.  I made the tube 3.5" long.  Long enough to ensure I could get a washer on and get to the bolt head with a socket or end wrench.  One of the last things in this chapter will be to flox the entire tube in place.

It took me longer to write this than to actually do it.  The only thing really left in this modification is to flox on a nut plate on the forward side of the alignment tabs once they are built.  Now we have to establish an accurate mounting location for the canard.

Onward!