UND Cessna Citation II Research Aircraft

The University of North Dakota owns and operates a Cessna Citation II aircraft (N77ND) for the purpose of atmospheric research. This aircraft type has a number of design and performance characteristics which make it an ideal platform for a wide range of atmospheric studies. The Citation II is a twin-engine fanjet with an operating ceiling of 43,000 feet (13.1 km). The turbofan engines provide sufficient power to cruise at speed of up to 340 knots (175 m/s) or climb at 3300 feet per minute (16.8 m/s). These high performance capabilities are accompanied by a relatively low fuel consumption at all altitudes, giving the an on-station time of up to 4 hours or more, depending on mission type. Long wings allow it to be operated out of relatively short airstrips and to be flown at the slower speeds necessary for many types of measurements. The Citation is certified for flight into known icing conditions.

The cabin measures approximately five feet in diameter and more than 16 feet in length. The minimum flight crew is pilot, co-pilot, and data system operator. Two additional seats are available for scientific observers.

A series of structural modifications have been made to the basic airplane. These include the following: pylons under the wing tips for a variety of probes in the undisturbed air flow away from the fuselage; a heated, 5-port radome for wind measurement; and an air inlet port and manifold for air sampling inside the pressurized cabin.

Instrumentation: The research instrumentation available on the Citation is listed in the Summary of Measurement Capabilities. Typically, the equipment carried on any given research project will be a subset of this list. The installation of instruments provided by other investigators can be accommodated, subject to space, weight and electrical requirements. A variety of 19-inch racks are available to accommodate standard instruments.

Click here for a chart of Citation II's Instrumentation Specifications.

Meteorology: The basic instrumentation package measures temperature, dew point temperature, pressure, wind and cloud microphysical characteristics along with aircraft position, attitude and performance parameters. The three-dimensional wind field is derived from measurements of acceleration, pitch, roll and yaw combined with angles of attack and sideslip and indicated airspeed. The aircraft parameters are supplied by an Applanix POS-AV strap-down gyro system with integrated global positioning system (GPS). Strap-down accelerometers provide lateral and longitudinal aircraft accelerations. Turbulence intensity can be derived from differential pressure transducers and accelerometer outputs. Cloud microphysical measurements are made with an array of Particle Measuring Systems probes (FSSP, 1D-C, 2D-C) mounted on the wing-tip pylons. These probes measure both liquid water content and icing rate.

Air Chemistry and Aerosols: A number of gas and aerosol sampling instruments are available. These include fast response O3, CO2/H2O and NO/NO2 monitors, and monitors for SO2, CO and SF6. Aerosol sampling equipment includes PMS passive cavity scattering and Royco light scattering probes, a condensation nuclei counter anda MEE-type cloud condensation nuclei counter.

Remote Sensors: A forward or side-looking video camera is also used to provide a visual record of flight conditions. A Bendix-King vertical profiling forward-looking weather radar can be viewed in the cockpit and recorded on video tape.

Data Acquisition and Display: The data are sampled at various rate from 4 to 100 per sec. The sampling is controlled by the onboard computer system which also displays the data in real time in graphic and alphanumeric formats while recording them on magnetic tape. The data can also be telemetered to a ground station and displayed in real time, or data may be telemetered from the ground to the aircraft. The data system is based on a project-customized windows system to allow flexibility in data acquisition and instrumentation in order to accommodate specific research demands

Air Parcel Tracking: The data system can also run a "pointer" algorithm which can be set to track the three-dimensional advection of up to three separate air parcels. This allows the aircraft to sample in a Lagrangian frame of reference.

Field Support: When in the field, the Citation is accompanied by a mobile operations support trailer. This vehicle houses technical support facilities, including calibration equipment for on-site quality control, and computer systems. The meteorological data collected on a research flight can thus be processed and examined within a few hours.

Contact Information: For further information about the University of North Dakota's Cessna Citation II Research Aircraft please contact:

For further Information contact:
Manager, Research Facilities
Department of Atmospheric Sciences
University of North Dakota
Box 9006 University Station
Grand Forks, ND 58202
Phone: 701-777-2184
Fax: 701-777-3016
Email: citation@aero.und.edu