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@Uvicsubmarine

PROJECT

Hull - Chinook III

This year the team chose to build a second submarine hull - Chinook III. Building the new hull allowed our team to accomplish four things: 

  • Firstly, the majority of our team was able to gain and expand their knowledge about how to make a fibreglass hull. We initially built our first submarine two years ago when the majority of our members were in the final semesters of their degree. Upon their graduation, it left a lack of practical knowledge among our team on how to build a hull. Over the course of the nine layups it took to build our new hull, we not only were able to assemble comprehensive documentation but also gain practical experience with fibreglass that will serve us well as we build our third hull in 2021. 

  • Secondly, building this new hull has also made it safer for our pilots to race. Chinook II has a plethora of snagging hazards attached throughout the inside of the hull made primarily of steel and wood (due to budget constraints) that are starting to wear from all the time they have spent underwater making it dangerous for our pilots if they were to catch themselves.

  • Third, the building of a new hull will allow us to map out a new hatch system. While the previous four-part submarine is effective (and super cool), we have found through working on the submarine underwater that it is not the most practical. Some sections (especially the front piece) are extremely buoyant and difficult to bring down to a submarine underwater and attach. Chinook III will have only 2 hatches, a human hatch for the pilot to enter and exit, and a safety hatch that will double as the safety buoy

  • Finally, building Chinook III would allow us to implement a modular mounting system, uniting the propulsion, safety release and dive plane systems into one piece. This system allows us to modify and improve these mechanical systems as a whole, making it easier to transfer the system between submarines and modify it for our new submarine next year.

Propulsion System

  • Propulsion mechanism: A conventional crank and pedal system with easily detached toe covers. This streamlined and simplified propulsion system production and allows easy implementation of future improved designs. The pedals span less than 30cm in diameter to minimize hull clearance. An adjustable shoulder brace allows accommodation of a variety of drivers’ sizes.  This brace allows the best, not smallest, driver to operate the submarine.  The pedal sprocket connects to a gearbox via a chain and a smaller sprocket to increases gear ratio and output shaft rotation speed.

 

  • Gearbox: Consists of a bevel gear train to transfer the rotation of shafts 90 degrees from the pedal mechanism to the output shafts. Within the gearbox, one input bevel gear receives power from the chain drive system. This then rotates two output bevel gears in the opposite rotational direction, each connected to their respective output shafts. The output shafts are concentric to each other, with one inserted within the other to have two counter-rotating set of propeller blades as the power-generation mechanism. The overall gear ratio will range from 1:3 to 1:7. Gearbox efficiency and hull drag calculations will determine the final ratio.

 

  • Propeller blades: Consists of 3-D printed PETG plastic material with reinforced carbon fiber layers. Each set of blades directly couples to their corresponding shaft for counter-rotational propulsion. A cone with decreasing diameter reduces the submarine’s stern weight and creates a more hydrodynamic water flow throughout the submarine’s aft. This year we have updated our blade design to be more efficient and produce less pressure drag. This update will entail the 3D printing of nine new blades which will then be press-fitted with an aluminum shaft and wrapped in carbon fibre. The blades will continue to be mounted into two contra-rotating hubs.

  • Thrust Block: This year we will be adding a thrust block to the propulsion system. The thrust block is designed to mount the Propulsion and Steering systems together on a single entity, allowing us to remove it as one piece. In the short term, this will allow us to remove the two systems from the submarine facilitating machining and maintenance. In the long term, it will allow us to mount the Propulsion and Steering systems directly into future submarine hulls we produce, regardless of the shape of the hull.

Control Surfaces

  • Rudder:  Placed aft of the propeller blades. When the submarine turns, it pivots its center of gravity; therefore, a rudder aft of the propeller blades attains higher turning moment due to its distance from the center of gravity. The velocity of the water behind the propeller blades is also greater than the velocity around the submarine, thus allowing for a higher velocity distribution across the rudder surface area, which then increases the lifting forces induced by the rudder. The rudder’s material composition consists of an EPS foam inner core and a hard fiberglass shell that allows for a light, yet strong, rudder capable of sustaining high velocities without deforming.

 

  • Diving planes:  Placed at the submarine’s aft, they generate lift forces for diving and elevating the submarine. Current designs utilize a low-drag, high-lift force NACA 0021 spaded profile. A spaded dive plane design reduces propeller-induced cavitation and drag. The dive planes’ material composition matches the rudders material composition.

 

  • Steering and Control: Mimics motorcycle controls, utilizing side-to-side handlebar motions to control the rudder and pedals for propulsion and a rotating handlebar to control the submarine’s dive planes. The handlebar is attached to a pivoting plate that directs push/pull cables to the rudder and dive planes accordingly.

Weight Rail System

At our last competition, the International Submarine Races in Maryland, DC, in 2019 we calibrated our submarine using bags of weight and foam attached to the inside of the hull above the propulsion system and below the steering system. While this system was somewhat effective, it was easy for the weight to shift and the submarine to lose stability. An integrated weight system using rail down the centre line of the submarine will allow us to attach weights to the submarine and lock them down ensuring our calibration and securing our materials to not be lost. Additionally, we will attach the dive tank along the rail and run any cable underneath it to make the inside of the hull smoother and more comfortable for the pilot. 

Electrical

After the success of last year’s electronic depth controller, the team is pivoting to concentrate on developing new systems to capture and log more data on the submarine state during operation. The system will record the submarine’s depth, hull speed, attitude, acceleration, shaft RPM and control surface angle. The data will be collected by an onboard computer, which will be displayed to the pilot on an integrated display, and stored on an SD card for further review and analysis. Collecting and displaying this data will not only allow the pilot to perform better during the races, but will also allow us to test and validate new designs and optimizations, and help inform design decisions for future submarines. To integrate these new features, the previous year’s system will be re-built using a more powerful microcontroller, new printed circuit board, custom-made battery pack, additional bulkhead connectors and overhauled software.

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