Question: Where is the horizontal thrust line on the VMAR Chipmunk 40 ARF removeable firewall?

Answer: The VMAR Chipmunk 40 ARF horizontal thrust line is 1-13/32" down from the top of the firewall.

Better Answer: The VMAR Chipmunk 40 ARF horizontal thrust line is 1-13/32" down from the top of the firewall. It can also be estimated by locating the cowl correctly on the fuselage and then drawing the horizontal thrust line so that it appears to pass midway through the crankshaft hole in the front of the cowl.