Tip Fairings

Step 5 CHECKING THE ELEVATOR TRAVEL AND INSTALLING TIP FAIRINGS

Here's a shot of the underside of one canard tip fairing. I've microed the block of foam, per plans, onto the end. In this shot the canard is upside down, elevators removed, and I'm getting read to install the hinge pin and locate the hole for removal of same.

I've drilled the hole for the hinge pin after installing it and am test fitting a piece of carbon fiber tubing I had left over from kite building.

When I started marking the foam for carving and sanding I realized it was too small. I may have installed it trailing edge down a bit too far. So, I microed a piece on top to make the whole piece big enough. I've done this before and it's worked out ok. Darn it, though, I should have measured to make sure the foam was big enough when I first made it and installed it.

Here's the tip fairing once carving and sanding had begun. The micro joint between the pieces is making this a little hard, but, all in all it's turning out okay.

Here's the top of the fairing once sanding and carving is complete. You can see the micro joint from adding a piece of foam.

A shot of the top, carved and sanded. I turned the canard over to carve and sand the bottoms 'cause I think I am going to carve and sand the bottom before I apply any glass.

Here's the bottom of one tip carved. I am using the line on the back of the foam as a guide for the carving, carving and sanding closer and closer to the line to make sure I get the right shape. You can see that the hole for the hinge pin "emerged" once the bottom was carved to shape. With that in mind I will have to re-think the carbon fiber tube idea.

Here's a shot with the hinge pin installed. It isn't buried in the foam very deep.

Another shot of the hinge pin hole after "emerging" from the foam once it was carved to shape. I decided to try a different hinge pin treatment.

I made the slot/hole for it a tad bigger as a first step.

Then, I shrunk a piece of heat shrink onto the hinge pin, after greasing the hinge pin lightly. I then installed the hinge pin back onto the canard with the elevators and piped thick micro into the slot that was left over.

Here's another shot of the micro filling the slot. I used some clear plastic tape as a dam on the end near the elevator. Thick micro helps to prevent runs and drips here.

Once it all cured, I twisted the hinge pin until it either popped loose from the heat shrink or the heat shrink twisted inside the micro. Pull out the hinge pin, then pull out any remaining heat shrink and sand off the excess micro. Voila! One perfect fit hinge pin slot!

Another view of the hinge pin slot.

After thinking about the tip fairings a while, I decided that I didn't want to have a bump where the micro joined the two pieces of foam. On other parts where this was done, I had ended up having a hard time making a smooth layup over the joint, 'cause the micro is pretty hard and no matter how hard you try, you end up with the foam sanding faster than the joint and thus you get a bump. So, I took a deep breath, got out a hacksaw blade and sawed them off!

I then microed on another, extra large piece of foam to do the tip fairings over. No joints in these babies! You can see the marker lines on the aft end of the fairing drawn per plans.

Since this was my second set of tips, I had the carving technique down pat. They went fast using a hack saw to rough, Shur-Form plane for coarse shaping then a sanding block and sandpaper wrapped can of spray paint for inside curves.

Yes, I probably vacuum bag more parts than I need to. Having said that, I decided I'd bag my tip fairings. I have a really long, really wide bag that I thought would work if I put the whole canard in it. I started by making some scrap foam filler block (I intend to bag with the elevators off) to prevent the lift tabs and other parts that stick out from trying to rip the bag. My son and I then did a test vacuum draw to be sure I could get the whole thing to seal. It did. It took a while to evacuate the bag, though. Next time I'll use the vacuum cleaner to get most of it out, then, switch to the vacuum pump since that little pump works pretty hard if you run it for a long time.

The tips seem like they'll bag well. There's a little wrinkling going on here but not so much I can't work it out when I do the real layup. I was worried the shape of the fairings would make the bag bridge from the upper right to lower left corner on the aft edge, but, it works fine.

I used some finishing nails to keep the foam blocks from moving when they were microed on. These left some interesting holes when they were removed. I've micro-filled them to prevent a divot from forming when I vaccum bag these.

Same thing on the other side. Tip fairings are ready for glassing and vacuum bagging now. As you can see, I have carved the tops and bottoms both, but, will only glass one side at a time as the plans call for a glass to glass bond on the aft end of the back and side.

I bought a monster vacuum bag a while back and decided to try it out on the tip fairings. Here I am (my soon took this picture) using the shop vac to pull most of the air out of the bag before I hook up the vacuum pump. Yes, I could use the vacuum pump for steps like this but it gets hot when it runs for a long time. Further, this bag, being so big, and hanging off the canard onto the table, etc. had a lot of air in it.

Here's my son James. He is a great helper on big stuff like this - a second pair of hands goes a long way.

Here's the top of one the tips after I've pulled a good vacuum and the layup is curing. I can see I'll have a couple of mild wrinkles in the corner.... grrrr......

Once the tops of the fairings were done, it was time to carve the bottom foam for a glass to glass bond. You can also see the pieces of pink foam I've used to prevent the vac bag from trying to rip when pulled tight over the hinge pins inserts.

Here's another piece of pink (insulating, from Home Depot) foam installed over the lift tabs. As indicated above, I did the tip fairings (both ends) in one vacuum bag. So, I had to prep the rest of the canard with tape, towels and foam so the bag wouldn't rip when pulled tight over things that stick out. Sure, the bag is stretchy and pretty strong, but, I wasn't taking any chances.

Here's the right-hand tip once the top and bottom glass was done. You can I used the hinge pin, installed in the inserts, to locate where the tube would go.

I went ahead and carved an extra-big hole/slot in the tip fairing, then, wrapped the hinge pin in tape until it was a slip fit in the carbon fiber tubes I wanted to install.

Then, after putting some box tape on the tip to keep the extra micro under control, I used thick micro to fill in between the carbon fiber tube and the tip fairing foam and glass. Once this cures, I should (if all goes well) have a nice tube installed in exactly the right place, centered on the hinge pin, for easy install and removal of the hinge pins when needed.

This step is complete - on to the Balance Weights!