The first actual build task is to cutout and remove “the doghouse”. The canard (front wing) is mounted in the nose of the aircraft. A part of the fuselage has to be cut out to allow placement of the canard. This piece that is removed is called (for some reason) the doghouse. First, the location of the canard has to be identified. This is accomplished by measuring from specific locations and marking where the canard will be.
In addition to cutting out the doghouse, I also had to cut out access ports in the keel and put in hardpoints for controls. The keel runs the length on the cabin and is between the left and right seats and the control stick is mounted in the keel.
It’s hard to visualize it, but this is the keel (upside down). The round opening wasn’t there this morning. One of the upcoming tasks is to build a cover. The opening will allow access to the control linkage.
An opening is also cut in the top of the keel towards the back. Because this opening is at the top and rather large, a stiffener is bonded and riveted in place.
In a slow-build construction where the two fuselage halves are not assembled, the keel is dropped into position once all the modifications are made to the keel. But with a fast-build, that’s a bit tricky since the keel won’t fit in through the door opening. So it has to be cut into two sections. Once cut, a flange is made which allows it to be reassembled.
In order to to mount controls to the keel, it is necessary to attach hardpoints to the fiberglass. This creates a strong mounting structure. In this case the hardpoints are created by mounting plywood to the keel and covering it with four layers of fiberglass cloth and epoxy.
Now that all the inspection panels have been created and the hardpoints put in, it’s time to install the keel. This is pretty significant since moving around inside the fuselage will be much more difficult once the keel is in.
The location of the keel is marked on the floor of the fuselage and then the front section of the keel in put in position. Holes are drilled in the flanges to hold it in place with cleco’s. Then the position is verified again. Once I’m certain that it’s right, I removed the keel, mixed up a batch of structural adhesive and applied it to the flanges. Then the keel is put back into position and the cleco’s are put in place to hold keel in place while the adhesive cures.
Once the adhesive cures, the cleco’s are removed.
From inside the keel looking forward at the canard bulkhead.
Then it’s time for lot’s of heavy layups. Most of these go around the front of the keel where it attaches to the canard bulkhead.
Once those layups have cured, the holes for the nose landing gear have to be opened back up.
Prior to installing the spar, the airplane is leveled (precisely) side-to-side and front-to-rear.
Normally, the spar is installed before the top fuselage is mated to the bottom. But in a fastbuild, the factory joins the two fuselage parts. This makes installing the spar… challenging. I had previously cut holes in the rear of the fuselage to accept the spar. First the spar is slid through the fuselage to check the position. Since the wing is mounted to the spar, the position of the spar is CRITICAL. First it is checked for center. It must extend out the fuselage equally on both sides (you wouldn’t want one wing longer than the other, right?). This is pretty easy; just measure each end to the center of the firewall. A nudge, measure, a nudge, measure, etc. Then it is checked for level left-to-right. In this case a small shim was needed on the right side. Then the spar is checked for level front-to-rear. The spar was perfectly level in this direction. Finally, the spar is measured for perpendicular to the centerline. This is done by measuring from the nose of the plane to the left end of the spar and comparing it to the right. Both dimensions were identical! This is starting to make me real nervous. This have been about the forth thing that usually requires a bit of adjusting to make it true.
Then the spar is marked for position and removed. Structural adhesive is thickened and liberally applied. Then we slid the spar back in trying to not smear it all over the place. Once it was back in place we had to recheck all the measurements. It only required a couple of tweaks to get it back in the correct position.
Then it’s left to cure overnight.
The main spar is an incredibly over-engineered C-beam that protrudes out each side of the fuselage about 5 feet. The main wings will bolt to this spar so it’s very important that it be securely attached to the fuselage. The initial installation is done with structural adhesive. But that’s only a start.
The first step is to make a foam bridge from the top of the spar to the top of the main gear bulkhead. Here’s the left side with a piece of divinycell foam bridging the space between the top of the spar and the top of the gear bulkhead.
Here’s the right side after I’ve coated the foam with a slurry of epoxy and microballoons. I’ve also created fillet in the corners to make an easier radius for the layups.
The same location with all the layups in place.
At the location above the spar, there are 10 layers of triax. Some of the layups run down the foam bridge and go almost to the floor. Others go towards the windows. In all, there are 12 separate pieces of triax. And that’s just on one side. The light colored patches are peel-ply. Thin dacron that’s placed over the layups and makes the surface of the fiberglass smooth. Very important at the edges since without it a lot of sanding is required.
The following day, did the left side spar reinforcing layups. No pictures since it’s the same thing I did yesterday. But, I was done by lunch
There are some really sharp edges so it’s a good idea to hit the edges with some sandpaper otherwise lots of blood will be left behind.
Next was front seat hardpoints. This is where the front seat are bolted to the floor.
This is a view of the floor looking froward where the pilot seat will be. On the right is the keel and the left (just out of view) is the door opening.
This is looking at the floor from the pilot side door. I’ve laid out the positions of the 2″x2″ square hardpoints according to the manual.
But wait, I’m a bit taller than the average person. So I decided to make a engineering change and move the pilot seat back an inch.
Because the floor is not flat (it’s lower in the center than on the sides), the outboard hardpoints have to be recessed so the the seat will be level. Here’s where one of the outboard hardpoints will go.
The next temporal black hole was how to attach initially. They’re going to have two layer of BID over them, but what to stick them on with to hold them in place. One place in the manual said:
“The inboard hardpoints can be installed on the surface and covered with two plies of BID.”
The other place said “Alphapoxy”. Now I haven’t had an occasion to use that before but my understanding is that it’s a lightweight epoxy. Now there’s going to be two layers of BID over top and that’s where the strength is going to come from so it probably doesn’t make THAT much difference but when in doubt, I’m going to spend time to remove all doubt. So after reading and re-reading, I gave up and called the factory. Turns out it doesn’t really matter. ARRGH! Another hour wasted. Maybe I should ship it back to Florida and spend a week every month down there?
Here are the hardpoints in place with micro bevel ready for BID layups.