The Black Stallion was designed to compete in the 2003/2004 AIAA/Cessna/ONR Design/Build/Fly contest, held in Wichita, KS in April of 2004. The aircraft was designed for a simulated aerial fire-fighting mission. The mission objective was to load up to 4L of water as quickly as possible, and then fly a prescribed course while dumping water through an orifice no greater than 0.5 inches in diameter. Flight score depended on the amount of water carried, and how quickly the entire mission could be completed. Aircraft were subject to several design constraints such as runway length, storage size, battery type and size, motor type, etc. The Black Stallion finished in first place at the contest.
- Wingspan: 6.6 ft.
- Wing Area: 5.56 sq. ft.
- Aspect Ratio: 7.83
- Airfoil: SD 7062
- Length: 4 ft.
- Width: 8 in.
- Height: 4 in.
- Motor: Graupner 3300-6 Brush with MEC 1.72:1 superbox
- Controller: Astro 204D
- Fuel: 16 CP-1300SCR NiCd batteries
- Propeller: 20x13
- Empty Weight (without batteries): 6.65 lb
- Battery Weight: 1.2 lb
- Payload Weight: 8.8 lb (4 L of water)
- Gross Weight: 16.65 lb
- Retractable boom with custom machined valve for water dumping
- Composite landing gear
- All molded construction
- Take off distance at full gross: 120 ft.
- Maximum climb rate full gross: 7.5 ft/sec
- Stall Speed at full gross: 24 ft/sec
- Maximum speed: 80 ft/sec
Water Delivery System:
One of the key features of the design of the Stallion is the retractable boom, water delivery system. The contest score depended largely upon how fast the mission could be completed, but the rules dictated that water dumping could only be done on the downwind leg. The rules also dictated that the water tanks could not be pressurized to accelerate the draining of water. In order to decrease the water drain time, the Stallion took advantage of gravity head. Drain time for the tank alone through a 0.5 in diameter orifice was approximately 30 seconds. With the addition of the boom, head pressure increased at the orifice such that the drain time dropped to approximately 15 seconds. This eliminated the need for the Stallion to slow down to dump the water.
The OSU Black design team was led by a Chief Engineer, and divided into three primary groups: Aerodynamics/Stability and Control, Propulsion, and Structures.
Chief Engineer: Aaron Sattre
Aerodynamics / Stability and Control:
- Robert Austin (Lead)
- Kyle Manahan
- Derek Nightingale
- Blair Lyons (Lead)
- Fred Beartrack
- Luke Smith
- Mike Ward
- John Dill (Lead)
- Matt Adair
- Shane Armstrong
- Cheng Chan Lee
- Cheng Yau Lee
- Susan Mattingly
- Michael Owens
- Kerry Turner
Pilot: Dan Bierly
Flight test pilot: Ronnie Lawhon
Spotter: Ronnie Lawhon
Faculty Advisor: Dr. Andrew S. Arena, Jr.
Assistant: Joe Conner
*(The above team roster does not include all people involved in the project)
The 2004 DBF profile involved two different missions. The mission that had the highest difficulty factor, and was worth the most points, was the fire-fighting mission. In that mission, the aircraft had to be loaded with water, take-off, fly a specific course dumping water in a prescribed area, land, and repeat. The "Fire Fight" score was calculated as: 2 * Lbs_Water / Mission_Time. Since mission time was so critical, the OSU Black team focused on methods for loading, and dumping water as quickly as possible. As described above, both the loading method, and dumping method relied on the use of gravity head. On the aircraft, that required a retractable boom of almost 2 ft. The boom connected to the center of the tank through a valve, and extended deep into the tail when retracted with a high-torque servo. The ferry mission was a mission where no payload was carried, and the plane had to simply fly 4 laps. It was worth very few points.
Overall score was calculated by multiplying flight score by written report score, and then dividing by RAC.
RAC was a "Rated Aircraft Cost" which penalized many aspects of the design. It included penalties for design parameters such as; aircraft empty weight, engine power, wing area, etc. A link to the complete rules may be found below.
- Avoiding "slosh" as the tank was draining, and changing the vehicle cg.
- Loading and dumping water as quickly as possible
- 120ft. runway limit
- Brushed electric motor and NiCd battery requirement
- Aircraft had to fit stowed in a 4ft x 2ft x 1ft box
- Wichita crosswinds
- Report Score: 94.9
- Flight Score: 12.1
- RAC: 6.74
- Total Score: 170.46
- Overall Place: 1st
The following sponsors contributed to the project. The OSU Black Stallion team greatly appreciates their support, and considers them members of our team. Without their support, the project would not have been possible.
Ken and Brenda Coulter
Ken and Jane Matlock
L. Andrew Maciula
Monroe and Naomi Yoder
NASA Oklahoma Space Grant Consortium
OSU Student Government Association
"It's rgh man!"
-Kerry Turner, in response to a question at the contest about what purpose did the retractable boom serve.