A great detail point for the Cole Palen Triplane is that the lower wingtip skids are made from ordinary axe handles. Even thought I have flown the Balsa USA triplane most of the 2013 flying season, I always planned to add this unique feature. It’s pretty easy to do.
Here’s the Old Triplane on the flightline several years ago at the Old Rhinebeck Aerodrome. Since the skid is a standard hardwares store item, the first thing to do is to go find one and measure it so I could figure out how big the 1/3-scale handles would be.
After drawing out a typical axe handle with my CAD program, I printed it out and pasted the pattern onto some 3/8-inch thick straight grain poplar.
A few minutes on the band saw and it’s ready for the belt sander.
I never try to cut right to the line. Instead, I use my belt sander and sand the part to its final shape.
As you can see, the grain is nice and tight and fairly straight. Full-size axe handles are made from ash or hickory.
Poplar is difficult to shape with a razor plane, so to make quick work of the shaping process, I used a 1/4 round router bit. Easy and quick, but you got to watch your fingers.
It doesn’t take long to knock off the corners, but you have to make several passes on each side of the part.
After a little sanding the axe handles look pretty good.
A little spray-on polyurethane gives the poplar look that hardwood hickory appearance I was looking for.
To make the attachment brackets scale like, and strong, I decided to make them from K&S Products’ brass sheet and tubing soldered together. I got the material from the local hobby shop. The actual attachment I am using 1/4 x 3/16 inch rare earth magnets. Magnets are really cheap. I got 20 from eBay for $6.
Using a fiber cut-off disk and a Moto-Tool, I cut two cups from the brass tubing and soldered them to the sheet straps. Soldering flux is the makes for a solid solder joint. That and lots of heat.
A regular clamping cloths pin holds the parts securely together.
The solder flows into and around the sections of tubing and secures the cups that hold the magnets securely in place.
To allow the magnets sit flush inside the cups, I removed the built up fillet of solder inside the cups with a high speed metal cutter and my Moto-Tool.
Simple and strong in design I used two holes in each attachment bracket to secure them to the axe handles.
Here the brackets and magnets are screwed to the axe handles. Notice the brass tubes inserted into the handles behind the brackets. These will house the aft attachment magnets.
With the magnets installed, (I used ZAP thick CA glue,) I transferred the attachment points to the wingtip. Center the holes on the wingtip ribs/capstrips.
A sharpened length of brass tubing easily cuts holes in the wing for the mating magnets. This was by far the scariest part of the project.
Thick CA is added to the inside of the holes and then after the magnets are inserted, I wicked thin CA in around the magnets. The thin CA glue helps secure the magnets in place and binds the fabric covering to the underlying wood so it won’t later on come loose or wrinkle.
After the glue dries, the axe handle simply snaps into position because the magnets attract each other. It is important to properly position the north and south poles so they attract each other. A little painting comes next.
The straps are actually made from two layers of Hobbico 1/4-inch-wide black pin striping tape with the ends glued down with thin CA. Then the brass was painted black, and the whole section is sprayed with clear polyurathane to seal everything up.
The finished job looks pretty good and is designed to easily “breaks away” or pivot and lay down should the axe handles get bumped during a landing or a tip over. A little more weathering and the wingtip skids will be finished! Hmmm, maybe a little dried on mud at the tip…
Be sure to stop by the MAN booth at the upcoming WRAM Show (Feb. 21 – 23) and let me know what you think of the Balsa USA Fokker Triplane. I will have it on display in the Static Competition this year.