Seagliders are autonomous underwater vehicles that move throughout the water by changing the internal buoyancy of the vehicle to have the vehicle rise and fall in the water. When the vertical motion from the change of buoyancy is in conjunction with the wings from the sea glider, a horizontal motion is also created. By only having to change the buoyancy to propel the vehicle forward, the operating range is greatly increased relative to that of a more conventional craft using a propeller or some other form of active propulsion. While the range of a seaglider is larger than many alternative crafts, the seaglider configuration is slow; with operating speeds of around 1-2 kts. This is problematic for the United States Navy’s purposes, as they would like to be able to get measurements of the water conditions in locations far away, without having to wait an extended amount of time for the data. In the past, it was only practical to launch a seaglider close to the location where the water conditions will be monitored, which means a deployment ship must be sailed close to the location in question. For the Navy’s purposes, this isn’t ideal because they might be trying to obtain these measurements in a hostile environment, or in a time sensitive scenario such as a search and rescue mission. The Navy recognized a need to find a way to quickly deploy a seaglider without putting their personnel and other equipment in harms way. The Naval Research Laboratory (NRL) has determined that a flying seaglider would solve this deployment issue. The seaglider could be launched from a ship from a safe location, fly towards the measurement location, and then submerge itself in the water to take its readings. This set-up poses its own unique problems, as landing a small aircraft in potentially rough water conditions is difficult to do without the aircraft breaking apart. Currently, the NRL is experimenting with different parachute configurations to allow the aircraft to land in the ocean at a relatively slow speed of 20 ft/sec. The NRL tasked North Carolina State University’s Aerospace Engineering Aircraft Senior Design Teams with the task of creating an experimental flying seaglider with new and unique parachute configurations.

Vehicle Requirements

• Use the fuselage that was defined by the NRL and make no major modifications that would alter its hydrodynamic sensitive design.

• Use symmetric airfoils with no incidence angle.

• Pusher configuration, with a single folding propeller.

• Removable pod or pods, containing the rocket casing and parachute system.

• Must be able to detach from fuselage for sea-gliding capability

• In-flight deployable parachute that will allow for a nose down landing.

• Use Aerotech 38 mm (240 or 360 sized) reloadable casing for rocket propulsion. Detachable nose to allow for sacrifical urethane nose cone.

Testing Requirements

Water Testing

• Capable of operating for 30 minutes in the water with dummy motor/batteries.

• Operate at a maximum depth of 5 meters. (Conceptually 100 meters)

• Demonstrate a neutrally buoyant state in the water.

• Alter buoyancy engine setting to demonstrate downwards gliding.

• Alter buoyancy engine setting to demonstrate upwards gliding.

• Vehicle be usable for flight after water testing.

Flight Testing

• Launch from a rail system using rocket propulsion to a velocity past stall speed (35 kts+).

• Demonstrate stable flight at a cruise of 60 kts.

• Flight duration of 10 minutes at full power.

• Deploy parachute in-flight, to allow for a descent rate of 20 ft/sec in a nose down configuration.

• Land on the sacrificial urethane molded nose cone onto the ground.

• Demonstrate removable rocket and parachute pod/pods.