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Distributed Flow Control Technologies


Hingeless Control Effector UAV Phase I

There has been a growing research effort to achieve effective hinge-less flight control, spurred on by advances in fluidic control. Under sponsorship of an STTR Phase I from AFRL through Aeroprobe Corporation, our team has worked for several years in developing hinge-less flight control technologies, and we first expanded the flight envelop to angles-of-attack as high as 25 degrees by embedding Synthetic Jet Actuators (SJA) close to the leading edge of the wing in order to manipulate/eliminate the size of the separation over the wing. The control is achieved through oscillatory blowing and suction along a slot positioned close to the leading edge and parallel to it.

Flow Control With SGFs - Theory, Experiment and Flight Demo

Top left part of the figure demonstrates the wind-tunnel implementation of the technique. To achieve hinge-less pitch control at low alpha we developed a Synthetic Gurney Flap (SGF) technology based on blowing from slots positioned very close to the leading edge (top right in the figure).

We subsequently implemented the SGF on a 9 ft. wing span UAV in order to replace the conventional ailerons with hingeless roll control means (bottom left in the figure).

SGF Actuation Phase I Results

One of the UAV wings with the implemented SGF is shown in Figure 3. It is important to notice that the original aileron, which spanned the entire wing length/span was replaced with only a 4 in. wide SGF. With these SGFs we test flew the vehicle 8 times, and were able to achieve considerable roll rates entirely hingelessly, as shown in Figure 4.

SJA Phase II

Hingeless Control Effector UAV Phase II

The Phase II program is conducted under an STTR Phase II from AFRL through Aeroprobe Corporation.  Our team implemented full leading and trailing edge hingeless control technologies (leading edge SJS and trailing edge SGF) on the wings of our Extra 300 UAV. Figure 1 shows the wing with the details of the installed hingeless actuators.

Figure 2 shows the Extra 300 UAV wing (without its exterior skin installed) in the test section  of our 3’x4’ test section closed-loop tunnel, where preliminary testing of the integrated wing is being conducted. After this, the entire assembled vehicle will be tested in the Aerospace Engineering, Oran Nicks 7’x10’ test section wind tunnel under realistic flight conditions.

The flight test program for Phase II is currently underway, with the preliminary test flights nearing completion.  For Phase II, the control of the non-conventional, hingeless actuators is being seamlessly integrated with the conventional control surfaces, such as the elevator and rudder. Two different flight control systems will be used for the test program: Piccolo Pro and the Athena Guide Star. 

SJA Phase II : SGF Actuation

Video Demonstration Links:

The flight test videos can be seen by clicking here >>

For More Information Contact

Dr. John Valasek, Dr. John Junkins, Dr. Othon K. Rediniotis.

Click Here for Info on Morphing Actuators:

Publications (Archival Journal Publications and Reports) :

  1. Puneet Singla, Kamesh Subbarao and John L. Junkins. "Direction-dependent learning approach for radial basis function networks," IEEE Transactions on Neural Networks, 18:203–223, January 2007.
  2. Lund, David W., Pollock, Thomas L., Valasek, John, Ward. Donald T., Hur, Gi-Bong, and Wilkey, John, "Flight Tests of an Unmanned Powered Parachute: A Validation Tool for GN&C Algorithms - Stage II," Final Report, NASA Johnson Space Center, November 2003.
  3. Junkins, J. L., Ward, D. T., and Valasek, John, "Vision-Based Navigation and Adaptive Control of Nonlinear Dynamical Systems," Progress Report for July 1997-September 1998, ONR Research contract N00014-97-0938, October, 1998

Publications (Conference):

  1. Singla, P., Subbarao, K., Rediniotis, O., and Junkins, J., “Intelligent Radial Basis Function Networks For Multi-Resolution Modeling: Application to Synthetic Jet Actuation and Flow Control,” 42nd AIAA Aerospace Sciences Meeting and Exhibit, Reno, Nevada, 5-8 January 2004.
  2. Traub, L., Miller, A., Singla, P., Tandale, M., Junkins, J., and Rediniotis, O., “Distributed Hingeless Flow Control and Rotary Synthetic Jet Actuation,” 42nd AIAA Aerospace Sciences Meeting and Exhibit, Reno, Nevada, 5-8 January 2004.
  3. Junkins, J. L., Singla, P., Griffith, D. T., and Henderson, T., “Orthogonal Global/Local Approximation in N-dimensions: Applications to Input-Output Approximation,” 6th Conference on dynamics and Control of Systems and Structures in Space, cinque-Terre, Italy, July 2004.
  4. Tandale, Monish D., and Valasek, John, " Structured Adaptive Model Inversion Control to Simultaneously Handle Actuator Failure and Actuator Saturation,” AIAA-2003-5325, AIAA Guidance, Navigation, and Control Conference, Austin, TX, 11-14 August 2003
  5. Gunnam, K., Hughes, D., Junkins, J. L., and Khetarnaraz, N., “A Vision Based DSP Embedded Navigation Sensor,” IEEE Journal of Sensors, Vol. 2, October 2002, pp. 428–442.




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