No, the Brodak .40 will not project out beyound the bottom of the cowling. You can cut it really pretty tight though. I did a seperate hopening for the venturi and the head, about 3/8 inch beyond the venturi before I started the head opening. I made the base of it the same width as the venturi opening, then just flaired it to meet the diameter of the head and made the opening in the bottom of the cowl the same size and shape of the head plus about 1/8 inch. You do need an opening back under the fuel tank area for air to be drawn out though. I made mine oval shapped about 1 3/4 inches wide and 2 1/4 inches long pretty well centered under the fuel tank. NOrmal theroy is about twice the area for air to exit as to leave. It doesn't show I I am really tightly cut around the motor so more exhaust lets it work well with no issues. The plane will come out just a tad nose heavy. I emailed Randy and he recommended 2 7/8 to 3 1/8 inch back from the leading edge of the wing at the fuse. I had to use a chip muffler to get it there and have the tank, about 4.5 ounce mounted at the back of the tank compartment with the Brodak .40. btw, an APC 10X5 is a good starting point prop. I'm going to try to get it to and 11X4 if I can get a gentle enough break from the engine. I'm flying on 63 ft lines with about a 9800 rpm launch with the 10X5 and muffler pressure. I know, but I seem to be the only guy on the planet that has trouble with stuff without pressure. Anyway, no overheat issues with powermaster 10-22 fuel and that combo.
Good luck, its a nice flying bird. I have 2 more in hte works, one more arf with an Aerotiger .36 and then a full build I'll finish during the winter for the aerotiger.
bob branch
Topic: Vector 40 ARF question (Read 1192 times)