Big John wrote in message . ..
Robert

The Beech 18/ C-45/ AT-11 were the same 'basic' airplane.

The first 40 built in the late 30's had 330 HP Jacobs with P & W 450
HP engines in the Military C-45/AT-11/etc.

I got some time in the C-45.with the 450 HP P & W engines.

Your R680 is the 300 HP Lycoming (Model HRE). Didn't find any mention
of this engine in the early D-18's but may have been a proto or first
engine before they went to the 330 Jake?


Don't forget that the early aircraft certified under TC's 630 and
A684 could have been powered by Wright 760's....

Craig C.