Misc Tail Const Photos

Not much variety here as I have been building all of my tail surfaces essentially the same way since the design of the original Mustang (Snaggletooth) series. The first photos in black and white are of the original 1973 molded Mustang tail surfaces construction. This tail set was lighter than I build today, the whole set with horns and hinges weighing 1 3/8oz ready to install. I just finished another set of the same surfaces which weighed 1 7/8oz. When I built the second set, the main differences in construction were to use narrower spruce spar caps and a thinner laser cut spar web assembly. It should have been lighter, but.... the original set was built with water thinned Tightbond which is probably one of the lightest possible adhesives. My new set was built, of course, with CA which doesn't lose much of its weight as it instantly cures. I am convinced that CA added 1/2oz to the tail surfaces and probably 3 to 4 ozs to the airplane as a whole. So, will I return to Tightbond? Nope, I'll just live with some increase in weight and try to reduce weight elsewhere. My bellcrank mount, for example, is lighter and stronger.

All of my stabs are built essentially the same with built up spars. Stab spar construction is basically a 1/4"x1/8" balsa web with 1/16"x3/16" spruce spar caps. The elevator horn is lightened, bushed and bound to the bare spar cap before any other parts are added. With the new Snaggletooth, I thinned the spruce spar caps to 1/16"x1/8" and used a laser cut three piece spar web assembly of 1/16" balsa to save weight. I did add short auxiliary stub spars at the stab point of maximum thickness for a little extra strength. This airplane is designed for modern .65s where the original airplane was designed for a 46. still, with a lighter main spar assembly, I expected to see a weight saving and was disappointed. I considered using carbon tape instead of spruce for my spar caps but decided on spruce. The carbon is light and very strong but in tension only. The spruce is strong in both compression and tension. Also these stabs were/are very light already and with their relatively thick airfoiled sections, very strong. The rest of the tail surface construction is 6lb 1/16" balsa sheet.

My emphasis lately has been in the shaping of the base of the vertical fin to match the fuselage with little or no "puddy". The Sea Furys used 1/32" balsa fillets. Even these can sometimes be avoided by adding a bit of shape to the bottom of the vertical fin.

Anyway, this is how I do it.