Skade RP-1 Autonomous Aerial Vehicle
David Tecker, Jackson Ernst, Ronan Paulsen
Skade RP-1 is an unmanned cargo aircraft design to service the Amundsen-Scott South Pole research base during their winter months. To meet the scientists and researcher’s needs at the station, we will be utilizing a 5700lb cargo capacity to deliver fresh food supplies, maintenance parts/equipment, and personal supplies, and more. Currently, there are no deliveries to the South Pole due to the -60°C average temperature, continuous darkness, and high winds that may exceed 150kts at certain altitudes. Continental missions are impractical due to seaports such as McMurdo Station being iced in. This necessitates a 19 hour intercontinental mission that spans over 6000 miles to the South Pole and back with no refueling.
To satisfy our primary stakeholders (National Science Foundation and the United States Antarctic Program), we developed Skade RP-1 with fuel efficiency and payload capacity as leading drivers of the design. The aircraft sports a high aspect ratio top mounted wing with twin Garrett TFE731-2 turbofan engines mounted underneath it. This gives us the most room for our cargo compartment and cargo door. The cargo bay is 20ft by 4ft by 4ft which allows us to fit up to five 4 ft square pallets to hold the cargo. These pallets can be loaded and dropped from the rear split cargo door shown in the image below. Cargo will be dropped using a low altitude parachute extraction system (LAPES) which will require the aircraft to descend to near ground level and have the parachutes pull the cargo out to be dropped to the ground.
For this evolution of our design, we wanted to specify key parameters of the systems of the aircraft and allocate space for them. The most important for our mission is fitting the fuel we need for the 6000 nautical mile round trip mission. Shown in green, the fuel tanks take up most of the wing as well as additional space above the cargo bay. A total capacity of 1740 gallons gives us a 10% margin to account for internal structures and fuel system components. To control the aircraft we are implementing a fully autonomous flight control system that will be capable of completing the mission including takeoff, cargo drop, and landing. To add redundancy and alleviate some of the risks with an autonomous flight there will be a maintained satellite connection to the aircraft that in addition to GPS data will allow an operator to make mission adjustments as needed during the flight. As a final failsafe, ground stations will be established both at Christchurch and the South Pole to allow remote piloting of the aircraft if needed to perform the more critical maneuvers of takeoff, cargo drop, and landing.
We validated our system performance by creating a time-step simulation to model each phase of flight. Our standard mission, as seen from the plots above, shows that we can perform all phases of the mission with fuel left over to account for wind, mission delays, and other unforeseen events.
Because the budget of our customer is limited and the mission range is notably long, many design decisions were made to increase fuel efficiency, thus decreasing the fuel cost and fuel volume onboard. This driving factor lead our system toward a cruise lift to drag ratio (L/D) of 27 and cruise speed of 339 kts. This L/D value is markedly large compared to other transport jets, but is necessary to maintain a low fuel cost of $0.63 per pound cargo. Comparetively, the LC-130 that currently operates in Antarctica can deliver cargo for around $2.00 per pound cargo. Using aircraft cost models based on historical data, we are estimating the unit cost to be $60,000,000 with 5 airplanes produced, but this value can be significantly reduced if we target additional customers and increase production.
40,000 – 55,000 ft