If memory serves, the Mars was a design outgrowth of the famous Consolidated Catalina PBY patrol flying boat of WWII Fame. I could be wrong, but the Martin is basically just a bigger Catalina. I know for a fact that the hourly operating cost of the Catalina in today's dollars is in the area of $8,000 to $10,000 per hour, so the Martin has to be a little more. I had to give up flying when my Piper Colt got to be more than $100 an hour to operate.