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UAV Flight Tests @ A&M

From 2000 – present the Flight Mechanics Laboratory and Flight Simulation Laboratory in collaboration with the Center for Mechanics and Control has conducted six major UAV flight testing programs, for a variety of AFRL, NASA, and private corporations.  One of the UAVs tested is fully autonomous, with an auto-takeoff, auto-glide, and auto-land capability, while the others are semi-autonomous.  Two of the UAVs are dedicated sensor testbeds, two are dedicated control law and system testbeds, and two are dedicated control effector testbeds.  Each program and vehicle is described below.


Flight test :Autonomous Aeriel Refueling Demonstrations


To validate and demonstrate the Autonomous Air Refueling System (AARS), composed of the VisNav relative navigation sensor, and the Reference Observer Tracking Controller (ROTC) control laws, both developed by our team, we conducted the following flight test program.  The program is being conducted from 3 April 2006 – 31 October 2007 at the Flight Mechanics Laboratory, under sponsorship from FRL/MN and Boeing, under sub-contract to StarVision Technologies.  Fight testing of the first vehicle began in June 2006, and is still proceeding.  To date, more than 10 validation and verification flights of the tanker and receiver have been conducted.  The first air-to-air docking of the tanker aircraft and the receiver aircraft, without human supervision or intervention, is scheduled for 2nd Quarter 2007.


Visnav Flight Test 2006-07

UAV Proximity GNC using VisNav: Experimental Demonstrations, 2006.


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

Phase II flight Demonstration:

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

BUCKEYE autonomous parafoil UAV

This flight test program supported the NASA X-38 program by assessing the capability of various guidance and control algorithms for gliding re-entry into Earth’s atmosphere.  A second broad objective was to develop and validate the use of the autonomous Buckeye vehicle as a hazard avoidance testbed.  A total of 52 flights were conducted from 2000 – 2004 at the Flight Mechanics Laboratory.  Specific technical objectives were to evaluate heading control algorithms, targeting capability, and to validate the wind alignment and estimation performance attained by these guidance algorithms. 


Additional testing was conducted to quantify navigational errors (including actual deviations from the de-sired trajectory, biases, noise, and the like) achieved during simulated terminal phase maneuvering with the Buckeye vehicle.  A V& V effort was conducted to compare data from Buckeye flights to simulator predictions of its performance, and to extrapolate the findings to the X-38 vehicle in its terminal maneuvering.  This was done using system and parameter identification techniques to extract stability and control derivatives. 


BUZZARD Reconnaissance and Surveillance UAV

The Texas Buzzard is UAV platform capable of long duration flight, suitable as a sensor testbed, and also for competition in the 2nd annual AUVSI UAV competition.  It began life as a RnR Products Inc. SB-XC sailplane model, but the Flight Mechanics Laboratory converted it into a motor glider by installing an O.S. FS-70 engine and landing gear.  A Piccolo autopilot was installed to provide an autonomous waypoint navigation capability


For sensors, the Buzzard has a video imaging and recording system with a GPS overlay system which allows location and heading information to be referenced to the recorded video for post-flight processing.  The onboard imaging system includes a small (11.6 gms) Panasonic CX161 CCD color video camera. This camera has 330 TV lines resolution, 5 lux and 52 degree lens.  The camera is mounted in the bottom of the UAV, pointed downward.  A GPS video overlay board OSD-GPS by Intuitive Circuits uses a separate 12 channel GPS system (PICO-GPS-SS from U-Nav) and overlays the current coordinates and speed of the vehicle onto the video image.  Finally, this image is recorded on-board using a Sony DCR-IP1 Micro MV digital video recorder for on ground analysis.

Our team won Best Technical Presentation, tied for 3rd Place Overall, and won the Safety Award  in the 2004 AUVI UAV Compeition, which is the first year that we competed.


MAXDRONE Controls and Systems Testbed UAV

This BAI Maxdrone, owned by Texas A&M University, was one of two produced in the early 1990s, and is slightly larger than the currently available BAI Dragon Drone used by the USN.  The Maxdrone was given to the Flight Mechanics Laboratory as a gift from Lockheed Martin.  It is a high performance UAV ideally suited to a controls and systems testbed, due to its large internal volume and payload capacity.  The wings are manufactured with fiberglass/foam sandwich construction, and the fuselage is plywood/foam and fiberglass. Hatches and cowls are constructed of fiberglass.  The Maxdrone is currently in flyable storage at the Flight Mechanics Laboratory .



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