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@Uvicsubmarine

PROJECT

Hull Design

Characteristics

  • Divisible hull: Current flight regulations stipulate luggage must be smaller than 130 cm in linear dimensions. The ability to transport the hull as carry-on luggage, instead of in shipping containers, drastically reduces cost.

  • Horizontal seams: In this arrangement, the entire FWD Top section doubles as the pilot’s escape hatch. If the seam were in the vertical plane, then an escape hatch would have to be cut through intersecting seams, and the hull’s side. A side hatch is unfavorable because asymmetry creates imbalance and limits where controls can be mounted.

  • Standardized internal component mounts:  This allows components to be easily removed for maintenance and transportation and replaced with new UVSRC designs.

  • Hull material and structure: A fiberglass hull on which components are mounted via the standardized internal component mounts. Mounting directly to the hull saves space.

Above: the excess is being removed from the nose cone after molding

Propulsion System

Characteristics

•          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.

 

•          Support structure: An aluminum frame attached to the hull at many points connects all parts of propulsion system. This allows propulsion system testing from outside of the submarine, providing flexibility to the testing process.

 

•          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. The 2018 submarine design implemented a Kort-Nozzle Propulsion System, that increased propeller blades efficiency by elimination of cavitation, and redirection of fluid flow to a concentrated direction.  This design also allows a rudder placed aft of the propeller blades.

Steering-Control System

Characteristics

•          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.

 

•          Kort Nozzle and support:  The nozzle is placed around the propeller blades to funnel as much fluid mass flow as possible, and to reduce propeller-induced cavitation and thus increase propulsion efficiency.

A nozzle also enables an attachment point for the rudder. The nozzle itself will be supported by four fins that attach to the propeller cone through the use of fasteners. The Kort nozzle composition consists of four 3-D printed PLA pieces which the pieces to be fiberglass coated. The fiberglass coating allows precise nozzle profile to reduce drag. 

 

•          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 handle bar is attached to a pivoting plate that directs push/pull cables to the rudder and dive planes accordingly.

Stability-Buoyancy System

Characteristics

•          Air diaphragms: Placed throughout the length of the submarine, these add positive buoyancy to counter-act the submarine’s negative buoyancy. The air diaphragm’s volume will be calculated by analyzing the buoyancy forces required to balance the overall weight of the vessel.

 

•          PVC foam pockets: These create positive buoyancy, and counterweights create a low center of gravity. The low center of gravity ensures stability and increases propulsion efficiency. Lead pockets form the counterweights as they are easily formed and mounted to the submarine’s hull.

 

•          Buoyancy compensating device: It is common for submarines to lose weight as air is released from the air tanks. A BCD ensures a proper submarine level by accounting for this change in mass.

 

•          Air tank selection: This includes the design and configuration of an air supply system. This includes the main air tank for the pilot while operating the submarine, and two pony tanks; one to meet the competition requirements, and the other to supply the BCD with air. Working with the master diver, the stability and buoyancy team will ensure that the air supplies meet all requirements for the competition.

Safety Release System

Characteristics

•          Safety buoy: Minimizes risk of driver injuries. A high-visibility surface-marker buoy allows the driver to signal for help, if necessary. The 2018 submarine’s safety buoy design had a net buoyancy of positive 500 grams, and attached to the submarine via a 10m long, 5mm diameter, highly-visible floating line stored on a reel for easy release. The line between the reel and buoy passes through a tube to prevent snags. The reel is externally mounted to the buoy. The cage and reel assembly are fastened to the submarine’s hull to provide a strong bond between hull and line; because the line is used to recover a sunken submarine. The buoy is mounted inside the hull with its outer boundary flush against the hull surface to attain a smooth fluid flow over the hull. 

 

•          Dead man’s switch: Using a “dead man’s handle” clutch (akin to bicycle brakes) the safety buoy releases automatically if the pilot is incapacitated and unable to squeeze on the clutch handle. An override mechanism eases operation while the submarine is behind the starting line.

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