Cozy

Chapter 10 - Canard Construction



The Plan

In this chapter we will construct the canard using R1145MS airfoil, which has no trim changes in rain. The canard is the most important and most critical airfoil in the airplane, so construction should be done carefully. The canard consists of 5 foam cores, 2 outboard, 2 inboard, and one center core. A trough is cut into the top and bottom of the inboard and center cores to accomodate an efficient, tapered thickness spar cap. A vertical shear web is installed after slicing the inboard and center cores at the forward edge of the trough. the shear web is strenghtened locally where the lift tabs are installed. The canard must be built without twist, so the cores are jigged and incidence checked before installing the skins. The bottom spar cap and skin can be put on in one layup, then the canard is turned over. After rechecking for absence of twist, 1 inch blocks of high density foam is installed for the elavator brackets. The top spar cap and skin can now be installed.

Here we are cutting the foam, the big blocks are cut down to sizes for the components. Then the smaller blocks are used to make the airfoils. Notice the fish tail on the small cores. This is extra added to aid in construction and will be removed later, before glassing the top.

The foam cutter is a Hot Wire. We affectionately call it Frankenstein. It sparks before it comes to life! I made this one from a 2x4, two 1/2 inch pipes, and some safety wire. I use a battery, battery charger and a resistor bank in series to power the hot wire. The resistor bank is nothing more than another wire strung on a board between some screws. The Zigzag pattern allows me to choose whatever length of wire that gives me the correct amount of heat. Once you do a hot wire cut for the first time it becomes a piece of cake. There was some apprehension, but you work on just cutting out the blocks first. So you feel much better about how you are doing when you get to the important cuts. In the first picture I'm looking at the resistor bank. In the second HELP, FRANKENSTEIN HAS GOT ME! I know it's a sick joke. My build partner made me do it.

This is what the cores look like whenever they are done being cut.

The canard pieces are in the jig, assembled and ready to glass the spar cap once it dries. The sheerweb is layed up on the foam to form a C over the forward edge for the full length. It is wrapped onto the top, forward face and bottom.

The lift tab attach plate is inbedded into the foam and microed into place.

The canard has been microed back together and the outboard cores added to the ends. Next the bottom trough has been glassed in with UNI tape and the bottom microed for the it's layup. Here we have glassed the spar cap and the bottom of the canard.

We had to come up with a method of easily applying the glass to the canard. Here we are laying it out to cut, once the layers are cut then we prep to put it onto the canard.

We will micro the top then lay the glass onto it. Our Uni dispenser worked a lot better than when we did the bottom.

This is my first lifting surface, so I wanted to try it out. Unlike Burt, I didn't strap it on the top of a pickup and test it. I did it the fun way, I chased my son around the yard with in this position. It did surprise me with amount of lift it would generate at those speeds.

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