: A low speed wind tunnel study to quantitatively evaluate the performance (lift and drag) of a circular cylinder and comparable 50% ellipse was conducted Circular cylinder performance was evaluated at slot positions of 80 deg to 135 deg, measured relative to freestream; 50% ellipse performance was measured for angles of attack between -5 deg and 30 deg Tests were conducted at three blowing coefficients, 03, 04 (optimal historically) and 05, to evaluate tailboom performance sensitivity Circulation control test results revealed optimal c1 values at an approximate 116 deg slot position, corresponding to cd values no greater than that of a smooth cylinder The 50% ellipse results revealed optimal c1 values at approximately 18 deg AOA, though associated with considerable drag For all three blowing coefficients, the circular cylinder L/D values were consistently three to four times greater than their 50% ellipse counterparts Recommendations for future NOTAR(TM) tailboom design modifications and later research are made

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Wind tunnel performance comparative test results of a circular cylinder and 50% ellipse tailboom for circulation control antitorque applications

The canard configuration offers a number of advantages over the conventional tail aft arrangement and has been successfully used since the earliest years of aeroplane flight. The canard configuration has a significant disadvantage in that the trailing tip vortices can interfere with the wing which is the main lifting surface of the aircraft. Winglets attached to the canards are a potential means of relocating the vortex to a more desirable position. The aim of this project was to visually investigate the tip vortex position improvement of the winglet on a canard. This was achieved through the use of wind tunnel testing of a model canard configuration and determining the relative change in position of the tip vortex with the addition of a winglet. The model design and development was supported by a thorough literature review of the aerodynamic benefits and design detail of winglets and the design requirements and issues on canards. Visualisation of the vortex position was achieved through the use of tuft visualisation methods. Testing of the model involved comparing the change in intensity of the canard tip vortex and downstream interference effects on the wing with the addition of winglets. The conclusion was drawn that the addition of winglets to a canard surface visibly decreased the canard tip vortex and repositioned it to the winglet tip.

Investigation into the Application of Winglets on Canards for Tip Vortex Position Improvement

Effects of a Closely Coupled Static and Oscillating Canard

: For over half a century the NPS Aerolab Low Speed Wind Tunnel located in Halligan Hall of the Naval Postgraduate school has served to provide students and facility with meaningful aerodynamic data for research and problem analysis. New data acquisition hardware was installed three years ago but never fully verified, and contained no integrated software program to collect data from the strain-gauge balance pedestal. Existing National Instruments based hardware for the NPS low-speed wind tunnel was reconfigured to obtain data from the strain-gauge pedestal. Additionally, a data acquisition software program was written in LabVIEW(C) to accommodate the hardware. The Virtual Instruments (VI) program collects and plots accurate data from all four strain gauges in real-time, producing non-dimensional force and moment coefficients. A research study on the performance of an OH-6A helicopter fuselage was conducted. NPS Aerolab wind tunnel tests consisted of drag, lift, and pitching moment measurements of the OH-6A along yaw and angle-of attack sweeps. The results of the NPS wind tunnel data were compared against testing conducted on a full-scale OH-6A helicopter in NASA Ames' 40 ft. x 80ft. wind tunnel, along with the U.S. Army's Light Observation Helicopter (LOH) wind tunnel tests. Results of current testing substantiate the LabVIEW(C) code.

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Upgrade of a LabVIEW based data acquisition system for wind tunnel test of a 1/10 scale OH-6A helicopter fuselage

Guidance and control of artillery shells using roll coupled guidance fuze is a less explored research area due to high spin rate of artillery shells during their flight. The advancement of technology in sensors and navigation available at low cost has made it possible to guide and control spinning artillery shells. Conventional guidance fuze used to guide artillery shell is roll decoupled with its spinning body due to its high spin rate. This research considers roll coupled guidance fuze at nose of 155mm artillery shell. Detailed Mathematical model of spinning projectile is developed, then Guidance through Impact Point Prediction (IPP) by ignoring aerodynamics for guidance is used to guide projectile towards target, which is implemented with proportional controller with saturation. Guidance Fuze or Precision Guidance Kit (PGK) at nose of projectile contains movable canards, controller, sensors and actuators. Controller runs the control algorithm, which controls the projectile by deflecting canards through actuators with the phase lead to improve the performance. Forces and moments of canards have been modeled with the sizing of canards surfaces. Results are analysed using Monte Carlo Method which models sensors, variations in initial conditions and aerodynamic coefficients to model different environmental conditions. Results show that correction made in trajectory by guidance algorithm reduce Circular Error Probable (CEP) and average miss distance.

Guidance and Control of a Spinning 155mm Artillery Shell

: A wind-tunnel study to find the lift and drag characteristics of a low-aspect-ratio wing/body configuration from an angle of attack (AOA) of -8 to 50 degrees was conducted A further study to find the comparative lift enhancement using the same wing/body with a close-coupled canard for wing/body angles of attack of 10, 22, 34, 40, and 48 degrees and canard deflection angles from -25 to 25 degrees was carried out It was found that a properly-located canard enhanced the lift at all tested angles of attack, compared to the baseline wing/body configuration results The lift enhancement was maximized in the post-stall regimes, reaching values up to 34% A small improvement in lift- to-drag ratio was noted at all tested angles above 10 degrees angle of attack

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John M. Kersh

Papers

Lift Enhancement Using Close-Coupled Canard/Wing Vortex Interaction