Flight Performance of a Circulation Controlled STOL Aircraft

Loth, John L.; Fanucci, J.B.; Roberts, Sean

doi:10.2514/3.58647

Cited by 40 publications

(14 citation statements)

References 3 publications

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“…The gain obtained here is around 20. This compares against [2,4,7,18]. The achievement of a gain of 20 with a relatively low h CC /R CC of 6.7 per cent demonstrates that the CC slot and plenum geometry have been implemented successfully.…”

Section: Control Lift Curvementioning

confidence: 92%

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Application of circulation control for three-axis control of a tailless flight vehicle

Wilde

Crowther

Harley

2009

Proceedings of the Institution of Mechanical Engineers, Part G:

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The application of circulation control (CC) manoeuvre effectors to a tailless flight vehicle enables the possibility of providing control moments about three axes without the use of conventional control surfaces. Strong similarities exist between the use of split flap elevons and CC units used as trailing edge devices for the provision of three-axis control. Both control types can produce independent roll and pitching moments by lateral symmetric operation. Yawing moments can also be produced by simultaneous blowing from upper and lower CC slots increasing the local section axial force. An existing datasheet method for predicting the lift and pitching moment increments for plain flaps is modified to support some aspects of sizing CC devices; however, there are some significant gaps such as high fidelity models for the prediction of Coanda jet separation from the curved trailing edge, which require further research. A case study is presented in which the provision of three-axis control moments using CC is evaluated for a tailless 20 kg class gas-turbine-powered model aircraft. Wind tunnel experiments are used to demonstrate the validity of the aerodynamic design of the vehicle and the ability to produce control moments from CC sufficient to meet basic trim and manoeuvre requirements. The peak values of CC control gains achieved for δC L /δC µ is 20 and the control gain for δC D /δC µ for use as part of a 'thrust'-based yaw control scheme from blowing from both upper and lower slots is low (∼0.5); however this is sufficient to trim the case study aircraft at 8 • of sideslip at cruise conditions with 10 per cent mass flow bleed from the engine. For lateral symmetric operation of CC controls, the change in pitching moment with control lift increment has been shown to be similar for both CC and flaperon devices (dC M0 /dC L flap = −0.76 and dC M0 /dC LCC = −0.6), confirming that the underlying aerodynamic mechanism is similar.

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Section: Control Lift Curvementioning

confidence: 92%

“…Given the extensive literature on CC dating back from the 1970s [1][2][3][4][5], it is relevant to ask how the work described in this article provides an original contribution to aerospace engineering practice. Historically, the focus of CC research has been for improved high lift performance.…”

Section: Introductionmentioning

confidence: 99%

Application of circulation control for three-axis control of a tailless flight vehicle

Wilde

Crowther

Harley

2009

Proceedings of the Institution of Mechanical Engineers, Part G:

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“…The first flight demonstrator was built in 1976 by West Virginia University (WVU) and was equipped with a small retractable Coanda surface TE flap, increasing C L from 2.1 to 5.3 for a blowing momentum coefficient of 0.12 [35]. Also in the late 1970s, the CC concept was used on a modified U.S. Navy A-6 flight demonstrator achieving a lift augmentation factor of 2.2 [36].…”

Section: Circulation Controlmentioning

confidence: 99%

Application of Circulation Controlled Blades for Vertical Axis Wind Turbines

Shires

Kourkoulis

2013

Energies

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Abstract:The blades of a vertical axis wind turbine (VAWT) rotor see an inconsistent angle of attack through its rotation. Consequently, VAWT blades generally use symmetrical aerofoils with a lower lift-to-drag ratio than cambered aerofoils tailored to maximise horizontal axis wind turbine rotor performance. This paper considers the feasibility of circulation controlled (CC) VAWT blades, using a tangential air jet to provide lift and therefore power augmentation. However CC blade sections require a higher trailing-edge thickness than conventional sections giving rise to additional base drag. The choice of design parameters is a compromise between lift augmentation, additional base drag as well as the power required to pump the air jet. Although CC technology has been investigated for many years, particularly for aerospace applications, few researchers have considered VAWT applications. This paper considers the feasibility of the technology, using Computational Fluid Dynamics to evaluate a baseline CC aerofoil with different trailing-edge ellipse shapes. Lift and drag increments due to CC are considered within a momentum based turbine model to determine net power production. The study found that for modest momentum coefficients significant net power augmentation can be achieved with a relatively simple aerofoil geometry if blowing is controlled through the blades rotation.

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“…The initial wing/CCW system of the aircraft was redesigned throughout the effort, utilizing a circular trailing edge that folded out (increasing wing area), a drooped leading edge, higher pressure ducting for more uniform slot flow, and boundary layer suction at the hinge of the unfolding trailing edge flap that provided air for the CC blowing. 10,65 The BD-4 aircraft achieved the following design objectives with its CCW: The following CC flight demonstration was performed by the Navy in 1979, flying a CCW retrofitted Grumman A-6. 2,9 The aircraft was equipped with a completely circular non-retractable CC trailing edge, 10,34 slots that were powered by engine bleed air, 66 outboard aerodynamic fences, increased radius leading edge slats that were locked in a 25° deflected position to prevent leading edge stall, 5 a fixed Krueger leading edge flap that was added at the wing glove, wingtip jets to improve adverse yaw tendencies, 67 as well as an inverted leading edge droop added to the horizontal stabilizer to counter the increased downwash.…”

Section: West Virginia University Bd-4mentioning

confidence: 99%

Design and Performance of Circulation Control Geometries

Golden

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DESIGN AND PERFORMANCE OF CIRCULATION CONTROL FLAP GEOMETRIES Rory M. GoldenWith the pursuit of more advanced and environmentally-friendly technologies of today"s society, the airline industry has been pushed further to investigate solutions that will reduce airport noise and congestion, cut down on emissions, and improve the overall performance of aircraft. These items directly influence airport size (runway length), flight patterns in the community surrounding the airport, cruise speed, and many other aircraft design considerations which are setting the requirements for next generation aircraft. Leading the research in this movement is NASA, which has set specific goals for the next generation regional airliners and has categorized the designs that meet the criteria as Cruise Efficient Short Takeoff and Land (CESTOL) aircraft.With circulation control (CC) technology addressing most of the next generation requirements listed above, it has recently been gaining more interest, thus the basis of this research. CC is an active flow control method that uses a thin sheet of high momentum jet flow ejected over a curved trailing edge surface and in turn utilizes Coanda effect to increase the airfoil"s circulation, augmenting lift, drag, and pitching moment. The technology has been around for more than 75 years, but is now gaining more momentum for further development due to its significant payoffs in both performance and system complexity. The goal of this research was to explore the design of the CC flap shape and how it influences the local flow field of the system, in attempt to improve the performance of existing CC flap configurations and provide insight into the aerodynamic characteristics of the geometric parameters that make up the CC flap. Multiple dual radius flaps and alternative flap geometry, prescribed radius, flaps were developed by varying specific flap parameters from a baseline dual radius flap configuration that had been previously v developed and researched. The aerodynamics of the various flap geometries were analyzed at three different flight conditions using two-dimensional CFD. The flight conditions examined include two low airspeed cases with blown flaps at 60° and 90° of deflection, and a transonic cruise case with no blowing and 0° of flap deflection. Results showed that the shorter flaps of both flap configurations augmented greater lift for the low airspeed cases, with the dual radius flaps producing more lift than the corresponding length prescribed radius. The large lift generation of these flaps was accompanied by significant drag and negative pitching moments. The incremental lift per drag and moment produced was best achieved by the longer flap lengths, with the prescribed radius flaps out-performing each corresponding dual radius. Longer flap configurations also upheld the better cruise performance with the least amount of low airspeed flow, drag, and required angle of attack for a given cruise lift coefficient. The prescribed radius flaps also presented a favorable trait of keeping a ...

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Flight Performance of a Circulation Controlled STOL Aircraft

Cited by 40 publications

References 3 publications

Application of circulation control for three-axis control of a tailless flight vehicle

Application of circulation control for three-axis control of a tailless flight vehicle

Application of Circulation Controlled Blades for Vertical Axis Wind Turbines

Design and Performance of Circulation Control Geometries

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