The OSpray 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 OSpray name combines the OS for Oklahoma State, and the unique spelling of the bird osprey (a raptor found in aquatic regions) to represent the spray generated when the airplane is performing its mission.  The OSpray finished in second place at the contest.

Specification List: 


  • Wingspan:        6.45 ft
  • Wing Area:       5.2 sq ft
  • Aspect Ratio:    8
  • Airfoil:               SD7062 flapped


  • Length:        4 ft
  • Width:        0.422 ft
  • Height:        0.58 ft


  • Motor:        Graupner 3300-6 with MEC gearbox 1.82:1
  • Controller:   Astro 204D
  • Fuel:           16 Sanyo CP-1300SCR NiCd
  • Propeller:    18x12


  • Retractable boom
  • Composite landing gear
  • Molded wing and tail construction
  • Conformal water tank designed for fast loading and draining


  • Take off distance at full gross:    120 ft.

Water Delivery System:


One of the key features of the design of the OSpray 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.  Using the dynamic pressure from the ram air was calculated to be only marginally effective.  In order to decrease the water drain time, the OSpray 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 under 15 seconds.  This eliminated the need for the OSpray to slow down to dump the water.

Team Info: 

The OSU Orange design team was led by a Chief Engineer, and divided into three primary groups: Aerodynamics/Stability and Control, Propulsion, and Structures

Chief Engineer: Matt Stutzman

Aerodynamics / Stability and Control:

  • Jamie Zink (Lead)
  • Daniel Holland
  • Mak Sin Nee


  • Stephanie Shaw (Lead)
  • Ralph Iasiello
  • Greg Seefeldt


  • Jason Slaton (Lead)
  • Ali Akbar
  • Gitogo Churu
  • David Eudey
  • Robert Fischer
  • Nate Harris
  • Thomas Hays
  • Tiffany Ice
  • Jerod Matlock
  • Myrriah Rowden
  • Jon Weeks

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)

Contest Summary: 

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 Orange 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

Complete Rules

Official Contest Summary

Results Summary: 
  • Report Score:     80.53
  • Flight Score:       11.95
  • RAC:                  6.71
  • Total Score:        143.49
  • Overall Place:     2nd

The following sponsors contributed to the project.  The OSU Orange OSpray team greatly appreciates their support, and considers them members of our team.  Without their support, the project would not have been possible.

Brian Davis
Hideaway Pizza
Ken and Brenda Coulter
Ken and Jane Matlock
L. Andrew Maciula
Michael Heusser
Monroe and Naomi Yoder
NASA Oklahoma Space Grant Consortium
OSU Student Government Association
Robert Austin

Design, Build, Fly