PT Gunboat PT-61 Model specs

PT-61 Model - Specifications

Note: This model is under construction and specs may change. (Updated April. 14, 2017)

Basic Model as Recieved

This kit was purchased used (partially started). It also came with the accessory kit. Most of the accessories parts were not usable because of either poor manufacturing, lack of details, or not conforming to photos of the real boats. Running gear parts that were used are: Three propellers, shafts, stuffing boxes (outer covering), and rudders and posts. The rudders were significantly reduced in size, but slightly larger than what would be scale sizes. All new shaft supports were machined.

The model is the "Frank's Mosquito Boat Hobbies" Dumas kit for the PT-65, Elco, 77 foot hull. It is 1/20 scale. The parts used are: Hull, deck, superstructure shell, lower turret tubs, turret flanged rings, inner turret rings, and turret seats, and forward hatch.

All of the other parts That were in the base kit and accessory kit were not used and had to be made from scratch. This includes the smoke generator, vents, hatches, upper gun tubs, and all rub rails and deckwork.

Parts and Materials

Excluding the electronics and running gear (motors, props, rudders, etc.) the parts and materials varied. Some pieces (like the Bofors guns) were built of using several different materials. Below outlines the origins of various parts of the model:

Parts from the Dumas kit: Hull, Deck, Turret Bases (2).

The vast majority of materials used on this model is Styrene. This is in several forms, mostly sheet Styrene but also shapes (rounds, rods, tubing, etc.) were used.

Brass and copper were used in several places where strength was needed.

Wood was sparsley used in a few places. This is where some lightweight strength was needed.

3D Manufactured parts were used for the machine guns, mounts, ammo belts, and ammo boxes.

Model figure kits (plastic) were used to make the crew. Some of the crew members were made from resin where some of the kit figures were used to make molds.

Internal Electronics - Motors/Running Gear

Like the real PT boats, the model has three function propellers and three rudders. The motors are identified as follows: "1" left (port) motor; "2" center motor; "3" right (starboard) motor, all identified as looking down from the rear (aft) of the boat.

Motor 2 (center motor) has a 9.6V, 5,000 mhr nimh battery, fuse, and ESC. This motor is a "Master Airscrew" MA3550 7.2V 6A motor. The motor runs forward only via a servo driven switch. The fuse is 20A. This motor probably turns at least 12,000 RPM and is usually turned on when the other motors are at full speed giving an even accelleration. The pickup in speed is quite noticable.

Motors 1 & 3 (outside motors) each have their own 8.4V, 5,000 mhr nimh battery, fuse, and ESC. These two motors are Maubuchi RS540BA 12V. The two ESCs are Hobbywing Quicrun 1060 brushed waterproof units rated at 60A forward. The fuses are 20A. These motors are rated at 1,000 RPM per volt giving 8,400 RPM at full voltage.

Radio Control
     The radio control is a classic Ace Nautical Commander Gold Series 7 channel (5 usable channels) system. It is set on channel 69 (75.570 mhz).

     Both the transmitter and reciever have been modified to use shorter, base loaded antennas. The transmitter antenna is about 12-inches long and is removable via a BNC connector. The reciever antenna is about 8-inches long.

     The transmitter has been modified to have all of the channel slides-sticks on the front. This was done by removing the slide control channels from the side to the front below the throttle sticks.

     The two motor control "Throttle sticks" operate the left (port) and right (starboard) motors as each motor has its own speed controller (ESC). A center slide turns the middle motor off and on (no speed control). The rudder tiller operates all three rudders in unison. There is one spare channel which is currently not used.

     In this configuration the boat is brought up to speed by increasing the two throttle sticks gradually to full speed. Then the center motor switch is turned to on giving the boat more speed.

Cooling Upgrade

On another test run on February 21 2016, the center motor (high speed forward only) had overheated. This test run was longer than the previous one. A cooling coil was added to this motor and custom fittings made and installed through the bottom of the hull for water pick up.

At the same time the 3300 mah battery for the center motor was replaced with a 5000 mah battery, significantly increasing the run time for high speed forward.

Weapons

The weapons for this boat are: Two dual 50 caliber BMGs in the turrets; six dual 50 caliber BMGs aligned along the deck; two 40mm Bofors, one for and one aft. The original dual 50s contained in the accessory kit for the model are of a low quality and too heavy for the boat. New parts will have to be made.

The additional dual 50 BMGs and the 40mm guns were purchased from HR Products. They are of a very poor quality and too heavy for the boat. New parts will have to be made most likely out of resin.

Additional Details

Additional details are added to the model, and most will be scratch built. Figures will be made using Tamiya 1/20 scale car racing figures. They will be modified to reflect the proper uniforms and/or typical attire used on PT Boats of the period.