A Very Magnetic Tiger Moth
Moth broken down and ready to box (at left). Yes, all of those pieces (above) fit in the box! Note that the original packing material is used to keep parts from moving around and chafing each other.
have done this too many times, until this sim- ple idea struck me: after one side is set up, simply place another magnet on top of the tape you already covered the first magnet with. They automatically will orient them- selves to be of proper polarity—in a hurry! Now, put epoxy in the other sides’ holes
and put the pieces together and blue painter’s mask tape them to hold them to- gether until the other side sets up. 10. Flying wires and their keepers: For
the flying wire attachments under the low- er wing I used ¹⁄₃₂-inch soft aluminum rod and mane braiding rubber bands. The short course: the flying wires are anchored under the wing with a pair of small black horse mane braiding rubber bands that are at- tached to split rings of soft aluminum rod. I found that my daughter’s horse mane braid- ing bands worked great, so if you know a horsewoman you know where to find them. The rubber bands allow you to string the
wires and keep them taut. They also con- tribute to the shock absorption equation. I used the existing holes through the lower wings to run the flying wires with uphol- stery thread, but reinforced the hole areas— both sides—with plastic shipping tape and epoxy lined the holes with a toothpick. At the other end of each wing’s flying wire
run, the wires are attached to fishing tackle barrel swivels that are hooked to ¹⁄₃₂-inch soft aluminum rod keepers. The flying wire keepers go through holes on the rear cabane
struts and are looped around and epoxied to their own super magnets. Both keeper mag- nets are centered under the rear wing hold down magnet. This gives great holding power for flight,
but for a crash, or to take apart, they slide off and move toward their respective wing’s cabane strut holes. This allows the flying wires enough slack to unhook from the soft aluminum rod hooks. Three magnets, each on top of the other assisted by the magnet in the upper wing equals four magnets with poles aligned. There is no way you can easily separate them from this stack, unless a sideways force is applied to the two that act as flying wire keepers, and, even then, it takes some doing. The result is a very secure system that can be detached for removing the wings, with the soft aluminum open hooked ends providing some of the crashworthiness. 11. Stabs: The vertical stab is modified by
gluing a small diameter 1mm carbon fiber rod to the bottom of the existing tab. I found that gluing a thin piece of balsa to the foam, first, helped. I then sanded it even thinner and grooved it for the CF rod. The CF rod ex- tends a little forward of the slot so that when the horizontal stab assembly is held down by its super magnet, it holds the front of the vertical stab in place. This idea is borrowed from the Airtronics Olympic 650, which was a great break-down sailplane which I con- verted to electric power. It accompanied our
PHOTO: SUSAN BARNES
family on many road trips when our kids were young. One super magnet is put into the under-
side of the horizontal stab at its forward end. This lines up with a super magnet that is put into the ¹⁄₄-inch balsa fuselage span- ner. The force of these two magnets keeps the front of the stabilizer assembly in place. Now we just have to anchor the back end. Borrowing again from the Olympic 650
design, the rudder, after being freed up and then re-hinged, either with real hinges or Blenderm tape, will carry the load of an- choring the rear of the stabilizer assembly. We need structural strength here, because the final anchor for this unit will be a Robart style micro hinge that is embedded in the rudder, below the current hinge, which goes forward into a hole where the fuselage sides come together at the tail. The hole for the slightly cut-off Robart
hinge is filed into the foam with a sharp tipped round file and then epoxy lined, us- ing a toothpick, for strength. But the half that points forward is not epoxied into the fuselage’s receiving hole. It must be able to slide in and out as the tail assembly is at- tached or taken off. Only the rudder half of the hinge is epoxied in place. To put the stabilizer unit onto the model,
the front half of the Robart hinge is put into the fuselage tail socket, first, and then the stab assembly is lowered until the super magnet, at the front of the horizontal stab,
Boxed Tiggie!A simple cut-out in a paper towel tube (above) captures both the tail and the wing tips, while the middle of the fuselage is held in place using a #64 rubber band, which, in turn, is hooked to the box using a large paper clip. The free end of the rubber band and the paper clip are anchored with plastic shipping tape. Dick thanks Jon and Susan Barnes for permission to use their excellent in-flight photos of the ElectriFly Tiger Moth (at right). His flying field was snowed in at the time. Jon was the pilot and Susan the photographer. Excellent work, Team Barnes!
58 APRIL 2012
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