1:72 Ocasní plochy pro C-123 Provider

The Provider and its tall tail surface

The C-123 came about by converting an unpowered cargo glider into a powered machine and it carried from that origin an unusually massive vertical surface with a high-set rudder. The tail is one of the most conspicuous features of this aircraft and at the same time one of the places where older kits most often fall short in shape and in the depth of the control surface recesses. A replacement part therefore solves exactly the section the eye notices first on a finished model.

A casting against a pressed part in a small scale

In 1:72 scale the difference between the two technologies is most visible on the trailing edges. An injection mold needs a certain minimum thickness at the end of a surface for the cavity to fill at all, and the edge therefore stays blunt. Casting has no such limitation and the edge can run out to real sharpness. That is paid for in weight: resin is heavier than plastic and a replacement tail shifts the center of gravity rearwards. On a model with a nose gear that means adding ballast to the nose, otherwise the finished machine will sit down on its tail skid.

Metal for what cannot be cast

The photo-etched fret covers the elements that are meant to be really thin. A metal part carries a thickness that is unattainable for a casting at this scale, but it behaves differently: it bends in one movement and a second attempt tires the groove.

The fitting procedure

The original surface is cut off with a saw, the mating surface is leveled on a board with abrasive paper and the joint is glued with cyanoacrylate glue. Dry testing before gluing pays off, because the angle can no longer be adjusted once it has dried.