bgi
You don't want the clunk to fall forward into the front of the tank. I have seen more than a few crashes on take off only to find the clunk in the front of the tank.

I make my clunk lines so that they are 1/8 to 1/4" from the rear of the tank. The line should be able to swing around without hittind the rear of the tank. I will then hold the tank level and rotate it like the plane would be rolling and watch the clunk, it should touch all four sides of the tank without binding up.

You will most likely not be in a 90° vertical dive very long. The plane runs out of altitude real fast coming straight down. If you did have enough altitude and came straight down at full power chances are very good the the plane would flutter and not make it out alive with or without the motor running.

DEG