Chapter 10 The Canard
In this chapter you build the canard wing (the small wing in the front). This will be the most critical part I have made yet. While waiting on parts to get here, I started making my hotwire templates. These templates are guides to help you hotwire the airfoil and elevator from a block of foam to the correct shape and size. The numbers on the templates are to keep you and your hotwire partner at the same place on the templates simultaneously.
I started by gluing the templates to the appropriate sheeting. I used
three different materials for the templates. I used quarter inch hard board,
half inch plywood and a three quarter inch pine board. I then cut the templates
out and sanded them to their finish sizes with my drill press and drum
sanders and my table sander. Below are what three of the templates look
like glued to hardboard before cutting and sanding.
There is plenty of prep work in this chapter. I started building the
hotwire saw for cutting the foam. A hotwire saw uses electric to heat up a wire.
I found that two car battery chargers hocked up in series works
great for a power supply. I will need to wait until my parts come with the
correct wire before I can say for sure.
I ordered all of my metal parts from CG
Products. Their parts are CNC
machine made and anodized which is of much higher quality than I
can make in my garage.
To cut the foam blocks into wing cores you will need to make a hotwire saw. This turned out to be an interesting experiment.
The hotwire powered by two car battery chargers wired in series worked great. With this setup, I didn’t need to use a light dimmer to regulate the wire temperature. Combined, the two battery chargers were putting out 24 volts at 20 amps. Be careful selecting your chargers because the chargers can't be dummy proof with reverse hook up protection. Below is a picture of my version of the hot wire saw.
Using the hotwire saw, a friend and I hotwired the canard wing from blocks of foam. Cutting the foam with a hotwire is a very easy and a fun process. The cores came out smooth. It is an amazing process. We next cut out the troughs for the spar. You have to make sure that the taper of the troughs are going the right way so you end up with a right and a left canard wing. These will be built up with spar tape which is a very heavy gauge fiberglass cloth. The spar in a wing is what carries a large part of the weight during flight. Before I put away the hotwire saw I am going to cut the elevator for the next chapter.
After you make these beautiful canard wing sections, the plans have you cut the leading edge off of the cores. Then you make a straight fixture from 2" x 4"'s srewed to the work bench. This took some time to be absolutely sure that they were perfectly straight. Pull plenty of tight lines to make sure it is straight unless you want to be a pylon racer going in circles all of the time.
After you get the fixture completed, you set your cores into the
fixture and pin the cores up with long screws and after you finally
get the cores straight bondo the screws in place so nothing moves. I next made another fixture
to install the nut plates that the lift tabs bolt to. I will need this fixture
after the sheer web is completed so that I can locate the bolt holes and
re-drill them. 
Then I began the fiberglass lay ups for the sheer web. The first two
layups go end to end of the canard and each layer after the keeps getting
shorter in a way that you end up with a thicker sheer web in the center of the
canard.
After this you remove the canard wing from the fixture, remove the
fixture from the work bench and in my case build another fixture. I used two,
two by four by twelve feet. I had to do this because my work bench is only ten
feet six inches long, not long enough. I first screwed a two by four down to the
bench and then made it level end to end. Then I screwed the second one down and
made it level with the first board. I set my forms on the two by fours and ready
to build again.
I started out by installing the lift tabs which are
what will be holding the canard wing onto the fuselage. I triple checked all
part numbers and visually checked the parts for any cracks or anything that
doesn’t look right. The bolts go through the sheer web into a plate with nut
plates riveted to it.
This level will drive you crazy when you are trying to get something as perfect as possible. The digital readout reads in .05 degrees increments and it appears to be accurate within .05 degrees too. All of the fly poop must be brushed away to correct for .05 degrees. This is one great level.
Below
is a picture of the lift tabs.The bolts will be traped between the lift tabs and
the leading edge of the canard wing.
It is scarier then
hell to think these two pieces of metal are all that is holding this canard on
but next time you are a chair lift about a hundred feet above the ground, look
up to see what is holding you up there.
You will see one piece of thin steel welded to a cable.
Yikes
The canard
looks like it came out without any twist.
After aligning the leading edge and sanding it down to allow room for the sheer web, I thought I was ready to epoxy the leading edge onto the canard. I thought I should come up with another way to check it though because I wasn't feeling very confident about things. I took my hotwire template and traced it out onto a board, cut it out and sanded it to a perfect match. Below is a picture of what I came up with to check the shape of the bottom of the canard.
When I sat the gauge on the canard, I could
see that I wasn’t even close to being ready to epoxy things together. See the
gap between the gauge and the leading edge (right side of picture) foam in the
picture below. A little more work and it will be correct and
ready.
After I got the canard straight, twist free and the leading edge aligned as it should be, I taped and masked off the wing with duct tape and plastic to keep from getting epoxy on the wing. This is what it looks like at this point. I again cleaned out the epoxy pump and poured new epoxy into the pump to prepare for this layup.
Below is
what it looks like after the layup. It is hard to see what all happened but you
wet out the spar tape into the spar indentation in the wing. I used a glue
trowel that is intended for putting glue on the floor when installing vinyl
flooring to keep the fibers in the fiberglass tape straight and
tight.
Below is a
picture of the spar tape. How it is used is you put the spar tape into the spar
channel on the wing. You then cut the red thread on the right side and pull it
out. You then can pull the string out that is running perpendicular to the heavy
threads. This just leaves the heavy threads or cords of fiberglass. This is very
heavy material and is very strong. It took quite a bit of epoxy to wet this
fiberglass down.
After the spar tape layup is completed you do the wing skin layups which are a mixture of Bidirectional fiberglass and unidirectional fiberglass.
After
the layups have cured, you break the wing loose from the fixture. You next make
another fixture to hold the wing right side up to prepare for the glass work on
the top of the canard. I used a piece of 1 ¼ inch PVC pipe 12 feet long to
keep the trailing edge of the canard straight. I rechecked the canard for twist
and straightness. All is looking good. Below is a picture of the end view of the
wing before the whale tail got cut off from over the pipe.
Below is a picture of the whale tail cut off leaving the fiberglass from the bottom skin exposed.
I then
did the spar cap layup the same as on the underside of the wing but the trough
for the spar cap is deeper on the top of the wing so you are able to put more
spar cap fiberglass in the trough. By the time I finished the spar caps I used
55 yards total for both top and bottom and the plans parts list says you will
need 42 yards. I ordered 60 yards to be safe.
After the top spar is completed I made my 2nd navigation antenna and my glide slope antennas from ½ inch wide copper tape. I then laid them on the top of the canard and marked their location and the location of the coax cable. I then removed the antennas and removed what foam was needed to allow the antenna and coax cable to lay below flat with the surface. I next potted the solder joints with RTV silicone. I allowed a day for the silicone to setup. I mixed some dry micro to fill in where the coax ran through the wing. Below is what it looks like to this point.
After sanding and cleaning the wing, I did the skin lay ups on the
top of the wing core.
After
the top layups cured for a couple of days I removed the canard from the fixture.
I then sanded off the bondo that was used to temporarily hold the canard into
the fixture. I then measured the exact location of the trailing edge and made a
straight line and cut the trailing edge and sanded it with my four feet long
sanding block to the finish location. I sanded any rough edges off of the
canard. Below is a picture of the canard completed.
This completes chapter 10. At
the end of chapter 10, completed per plans except for adding the two antennas
with about 15 feet of coax, this chapter weighed 24 lbs. The total project
weight is 201 lbs.
From my calculations,
this makes the project 21 percent completed.
Now on to Chapter
11.
Below is an error I found in the templates. This is two
template (A & B) laying over each other. They should be the same but the
talk numbers are not in the correct locations.
If you have any questions, comments or concerns, feel free to
email me @ Jfisher59@gci.net