Big Girtha Build Part 10, Gluing Four Fins Evenly

Three fin models stand on their own without wobbling.
Four finned models that stand vertically on the fin tips require a few extra alignment steps.

It's a bit tough to see the rear end of the root edge when gluing these fins on. You want the intersection of the root edge and trailing edge right at the end of the body tube.
Enlarge the picture and you can see small tick marks at the end of the leading edge. The pencil ticks give you one less thing to worry about before the glue sets up.

Like in previous builds, a paper strip was wrapped around the start of the leading edge.
Glue the first fin on then wrap and tape the alignment strip around the tube. This isn't really needed, but gives you another point of alignment.

TIP: To get rid of the four fin standing "wobble":

Glue on (only) three fins as normal.
The fourth fin decides if the rocket stands without wobbling.

Apply glue to the root edge of the fourth fin.
Set the fourth fin on the remaining alignment line.

While the glue is just starting to set up on the fourth fin root, stand the model on a flat even surface.
With the glue still wet you can slide the root edge up or down until all the fins are even and the rocket doesn't wobble.
It won't take much movement to get the final fourth fin edge to the right location.

To find the C/G, the model was dry fitted with engines, wadding and parachute.
The 3/16" lug center was glued on the center of gravity.

Before any paint is sprayed, erase any exposed pencil lines.