When designing the modular system, there were some design decisions to be made. Here we state the reasons for out choices.
Sizes of modules
Although the design is in theory scalable to almost any size, it must be considered that … In order to standardize for manufacture, restrictions on allowed sizes was made.
The chosen diameter options are:
- 2.75-inch (70 mm), as it is commonly used for missiles (and is wide enough to accommodate standard certified 54 mm amateur rocket motors from Kosdon/AT, Animal, Aerotech)
- 5.0-inch (127 mm), fitting for manpads.
- 12.75-inch (324 mm), standard for light torpedoes
- 21-inch (533 mm), as it is the standard diameter for heavy torpedoes.
Materials of modules
The most common materials for rockets… missiles… torpedoes…
…basalt fiber,
Connections between modules
Requirement analysis showed that in-the-field assembly of modules was highly preferable, thus each module needing to fully proof against water, sand and other elements of nature, hence no open connectors/sockets between modules, requiring wireless communications between modules.
…inductive links
Data bus
Deciding on a data bus
Considering the physical layer, such as voltage, current, line code, signal reflections,
A standard data bus is preferable compared to a proprietary data bus, due to many factors;
- availability of lower cost electronic components
- lesser design time
- larger talent pool
Thus existing data buses / protocols were evaluated for this project:
- RS-422
- RS-485
- Arinc-429
- MIL-STD 1553
- MIL-STD 1553B
- MIL-STD 1760
- H009 + 16PP194 (aka Weapons Mux aka WMUX) [predecessor to MIL-STD-1553, from the mid-1970s]
- MMSI
- I2C (+ SMBus)
- SPI
- SpaceWire
- CAN
- BITBUS
- Time Triggered Ethernet (TTE): very low latency, high accuracy, low complexity and cost and a flexible network topology
- RapidIO
- SRIO
- NGSIS
- UART