RC sub FAQs
Note: The original WPCPU (introduced around March 2006) was
renamed Dynamic Diving WPCPU "DD-WPCPU" to distinguish it from
Static Diving WPCPU "SD-WPCPU"(with ballast system).
1. What are the advantages of the rectangular water-tight-containers(WTC)? Why are Puremtc's
Rectangular WTCs(such as WPCPUs) have several advantages:
1. Reliable waterproofing. The drawing below explains the waterproofing mechanism of a
typical rectangular WTC.
WTC in the drawing is divided into 2 levels(top and bottom level). They are separated by a board(shown as
red in the drawing) The rectangular WTC is sealed by a piece of Gasket such as a rubber pad and a cover
at the bottom. Electronics such as receiver, ESC or other delicate equipments are located in the
top level. Battery, or other heavier objects are housed in the lower level. By housing the heavier objects
in the lower level, it lowers down the center of the gravity of the container and helps keep the WTC
stable(right side up). The rectangular WTC has 2 waterproofing mechanisms.
a) The gasket(rubber pad) at the bottom. b) Since the opening(gasket) side is at the bottom, even if cover and gasket
fail to stop water from coming in, air will still be trapped in the top level of the container. This will keep the
electronics and other delicate equipments dry in the event of mechanism a) failure or other type of leaking from the
bottom of the container. This is similar to a flipping over boat with air trapped inside the hull. Note: Top
side is permanently sealed, air can not escape from the top part of the container.
2. More compact. The reason that rectangular WTCs are more compact is simple. Almost all electronic
equipments(receiver, servo, ESC..) are rectangular. This allows them to be housed more compactly inside
rectangular containers than containers with other geometrical shapes.
3. Easy access to equipments inside. As shown in the above drawing, the rectangle WTC is sealed by a gasket and
a cover at the bottom. Once the gasket or cover is open, all equipments can be easily accessed. This makes maintenance
and repairment easy.
2. What are the advantages of modular design? Why do Puremtc's WPCPUs adopt such design?
A WTC that consists of several modules has several advantages:
1) Leak isolation. For example, a WPCPU consists of 3 modules. They are servo module, receiver module, and
motor module. If any one of them leaks, it will not spread to other modules.
2) More flexible placement. Different modules can be placed in different locations inside a submarine
or a ship hull.
3. How are WPCPUs constructed? What are the advantages of WTC constructed by this method?
WPCPU are assembled from computer-numerical-control(CNC) cut plastic boards.
Rectangular WTCs constructed this way have several advantages:
a) Accuracy. WTCs constructed this way do not have problems such as warping, shrinkage, dent, and
other problems typically associated with injection molding or vacuum forming. Computer-numerical-control(CNC)
cutting ensures certain degree of accuracy.
b) Size customization. Since no molding process is involved, the dimension of the WTC can be quickly
customized for fitting different sub, ship hulls, or applications.