PT-41
by Pat Matthews

1/20 PT-41 Torpedo Boat (Scratchbuilt)

Some photos of my 1:20 scratch built r/c PT-41... still some work to do, but at least it's recognizable now! More complete info at http://www.geocities.com/patspt41/

Update 29/03/06;

At long last, completed the PT-41 model- mostly required construction of the twin 50's and their vacuum-formed turrets, and a few other details. She sits atop a replica of the steel I-beam cradles that Elco shipped each PT on, as deck cargo on tankers. The model represents PT-41, MacArthur's ride out of the Philippines, as delivered new from Elco to the USN in July 1941. This is about the only time period where you should see the big hull numbers on the bow. Shortly after delivery, she was repainted overall dark grey. She was repainted again, overall green, at the start of hostilities. As delivered, she was not yet fitted with several items that appeared later- aerials, and 30 caliber MG's on pipe mounts.

Power is from a pair of 8.4v NiMH packs in parallel, through three independent ESC's to Graupner 8.4v Speed 600's driving Octura props. A micro-computer (Parallax BS-1) interfaces the 2 channel radio to the rudder and three ESC's, allowing four operating modes:

• Slow Ahead: The Speed 600 motors draw significant current, even when just turning over. To save on battery power, only the center motor is activated up to 50% throttle.
• All Ahead Full: After 50% throttle, the two outboard motors are ramped up on their own curve, until at 100% throttle, all three are running at full speed. The transition is smooth and effective.
• Slow Astern: Again to conserve battery power, and to avoid swamping, only the center motor is activated in reverse, and only to a maximum of 50% power at full throttle.
• Turn In Place: At zero throttle, turning the wheel will cause increasing amounts of counter-rotation of the outboard motors. Port helm causes a left-hand spin, starboard helm spins to the right.

All "scale" parts are scratch-built, except for the props and the US flag. Original Elco drawings from NARA were used, along with extensive 3D CAD to create hull and cabin lines. Hull is dual-diagonal planked in 1/32" basswood and covered in 1/2 ounce glass. Many parts were custom laser cut for accuracy and to save my sanity.