Battlin’ Pete II

10th International Submarine RaceDavid Taylor Model Basin Washington DC, Maryland

June 25, 2007

Design Team

David Hume Peter Moser- Design & Propulsion - Safety

Cale Jurin Cale Jurin - Pedals & Cables - Elevator & Controls

David Hume Peter Moser - Air Systems - Rudder & Controls

Goals

• To increase the speed obtained by Battlin’ Pete I while using the same hull form but different propulsion.

• Simplistic and robust construction. • Safe and easy control and operation. • Spend less than $100 on

construction and supplies.

Philosophy

• Mimic nature; i.e. the swimming motion of a penguin.

• Flapping foil propulsion studies led to identify strouhal number range .2~.4 for animals.

St = f a / Vwith an projected speed of 3 knots:

.3 = f (3’stroke)/ (5 ft/sec) f = .5Hz = 30 RPM target frequency

• Use leg press motion for increase in power input. (previous design had single fin with no counterforce)

Hull

• Reused hull form of Battlin’ Pete I with several modifications.

• Fiberglass hull with stainless steel tubing support frame.

• All hull extremities supported with backing plates and rubber spacers to alleviate stress concentrations.

• Buoyancy – Dock system Styrofoam – Ballasted with dive weights

Propulsion

• Hobie Mirage Drive used for foil due to flexibility (prevent stalling and separation effects) and proven effectiveness

• Controlled heaving and pitching motion

• Adjustable foot pedals to accommodate different drivers

• Sprockets and cam transmission.

ControlElevators

– Dagger boards used from small sailing craft. – Interconnected control of each fin by single

lever. – Located on forward third of hull length for

increased maneuverability.

Rudder – Plywood formed to steam lined shape of

rudders.– Utilizes a closed loop pulley system (crew shell)– Located on top of hull

Air Systems

• Two primary tanks in rack behind seat.• For exhaust vents used ventilation

cover from small inboard.• Corrugated canopy• Emergency bottle for entering/escaping. • Ratings

– Primary: 80 cubic feet– Emergency: 13 cubic feet

Safety

• Reserve buoyancy ballasted down with dive weights

• Emergency Buoy with high visibility line• Running Lights • Transparent easy opening cover• Non-skid pedals • Quick release harness • High visibility paint on all fins, stabilizers,

and elevators

Timeline

• Week 1-4 Design– Incorporate new design into original hull form – Removal of internals and dry planning/

measuring

• Week 5-17 Re-Construction/ Revisions– Collection/purchasing of materials – Measuring, cutting, welding, machining,

installing, painting, waxing.

• Week 17-19 Testing – In pool to fine tune buoyancy & stability– Controls and propulsion motion

Budget < $100• Majority of raw materials was used from scrap

piles around campus:– Aluminum mast from sailing team – Chair provided by Band Company Ward Room.

• Welding supplies and tools provided by Joe Kass (USMMA welding instructor)

• Hobie Mirage drive donated by Hobie Company• Items bought from Granger:

– Steel cable– Transparent PVC sheet– Velcro– Assorted nuts and bolts

Closing

• Learning Experience – Welding Techniques (aluminum, stainless steel,

mild steel) – Fiberglass Construction

• Modified original design continuously throughout construction

• Future modifications should include:– Hull form changes, reduce cross sectional area by

putting driver in prone position (drag reduction)– Additional drive either on top or directly behind in

tandem