Reinforcing the tail with triangle stock

Here’s the tail detail from the Bingo 20 plan.


It shows the horizontal stabilizer glued to the top of the fuselage, and the vertical fin glued to the top of the stabilizer, with no extra reinforcements on either part.  I’ve changed my mind several times over the years on the question of whether or not to reinforce the vertical stabilizer.  If you bump the tail as you’re putting the plane in the car the fin may break off.  Worse yet, if you break it while taking it out of the car, you have to just put it back in and go home.  So if you reinforce both sides of the fin with triangle stock it can take a little bit of knocking around without breaking.  This seems like a good idea, but what if you really bump the fin hard, but it doesn’t break off because of the triangle stock, so it breaks the whole tail off instead?  For a few years I subscribed to this logic and I simply glued the fins on my planes with medium CA, with no extra reinforcements.

That was back when I used to build planes in the basement, and I had to go up a narrow staircase, around a corner, past the dining room furniture, and out a door with a spring loaded storm door to get to my van.  I broke a few vertical fins off in those days, and I felt pretty smart.  Nowadays I don’t have to go through such a maze, usually.  I just go out one door and into the car, so for the past several years I’m back to reinforcing tails with triangle stock.  So let’s get back to the Bingo 20 I’m building now.  Here are the tail parts ready for assembly.


When I hold the fin in place it looks like the Monokote is lined up properly.


I’ve cut two pieces of triangle stock to the correct length.  I could install them like this:


But I think it would look better if I taper the ends and install them like this:


I covered each piece with a little strip of Monokote.


Then I attached the horizontal stabilizer to the airplane with medium CA glue.  You could also do this with epoxy or Titebond if you want to wait.  When the plane crashes, usually the tail survives unscathed, so using super strong glue for the fuselage joint seems unnecessary.


Next the fin and triangle stock are held in place and a line is drawn around the triangle stock with a fine point Sharpie marker.


Here’s what it looks like with the stick removed.


The next thing to do is to cut the Monokote away with a very sharp blade to expose some wood for gluing.  You have to cut well within the line so you don’t see the damage after everything is assembled.  After the film is trimmed the line can be erased with acetone and a paper towel.


Then the fin is carefully glued into place with medium CA and held up straight with a square to make sure it isn’t leaning to one side.


The triangle stock is glued into place on both sides with medium CA.


It could be said that on a plane such as the Bingo it would be more appropriate to make little reinforcing blocks to continue the lines of the turtle deck on each side of the fin.  However, given the angle of this turtle deck, the blocks would be only about a quarter inch long, so that’s no good.  The Bingo is just a knock-about sport plane so I’m not going to get too worried about how the tail looks.

Incidentally, the fin on this plane is nice and strong now.  I know this because after I took the last photo I was fumbling with the camera and I dropped the plane on the floor.  The entire tail broke off, but the fin-to-stabilizer joint stayed strong and suffered no damage.  So I glued the tail back on, and now it’s ready for equipment installation.