Mr. Ryan Barnhart Profile

Ryan Barnhart

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Proceedings Article | 28 March 2012 Paper

Steerable Adaptive Bullet (StAB) piezoelectric flight control system

Ron Barrett, Ryan Barnhart, Richard Bramlette

Proceedings Volume 8341, 83410Z (2012) https://doi.org/10.1117/12.915056

KEYWORDS: Actuators, Control systems, Aerodynamics, Weapons, Acquisition tracking and pointing, Missiles, Patents, Atmospheric modeling, Wind measurement, Electronics

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This paper outlines a new class of piezoelectric flight control actuators which are specifically intended for use in guided hard-launched munitions from under 5.56mm to 40mm in caliber. In March of 2011, US Pat. 7,898,153 was issued, describing this new class of actuators, how they are mounted, laminated, energized and used to control the flight of a wide variety of munitions. This paper is the technical conference paper companion to the Patent. A Low Net Passive Stiffness (LNPS) Post Buckled Precompressed (PBP) piezoelectric actuator element for a 0.40 caliber body, 0.50 caliber round was built and tested. Aerodynamic modeling of the flight control actuator showed that canard deflections of just ±1° are more than sufficient to provide full flight control against 99% atmospherics to 2km of range while maintaining just 10cm of dispersion with lethal energy pressure levels upon terminal contact. Supersonic wind tunnel testing was conducted as well as a sweep of axial compression. The LNPS/PBP configuration exhibited an amplification factor of 3.8 while maintaining equivalent corner frequencies in excess of 100 Hz and deflection levels of ±1°. The paper concludes with a fabrication and assembly cost analysis on a mass production scale.

Proceedings Article | 28 March 2012 Paper

Piezoelectric Low Net Passive Stiffness (LNPS) flutter test vane

Ryan Barnhart, Ronald Barrett

Proceedings Volume 8341, 834115 (2012) https://doi.org/10.1117/12.914986

KEYWORDS: Actuators, Aerodynamics, Wind measurement, Ferroelectric materials, Power supplies, Fourier transforms, Kinematics, Aerospace engineering, Nomenclature, Instrument modeling

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This paper outlines the design, fabrication and testing of a new, high performance piezoelectrically driven aircraft flutter test vane. This flutter test vane utilizes low-net passive stiffness (LNPS) actuator configurations to produce deflection amplification ratios on the order of 5:1 while maintaining full blocked moment generation capability. With an order of magnitude lower weight than conventional vanes, the LNPS flight flutter test vane is capable of producing larger amplitude structural deflections with smaller force levels because vane forcing waveforms, frequencies and phasing can be very exactingly controlled with respect to each other. The paper covers the fundamental driving theories behind the device, actuator geometry, test article layout, fabrication and testing. This device was wind tunnel tested at airspeeds up to 110 ft/s with excellent correlation between theory and experiment. Experimental tests show an improvement in angular deflection and delta lift forces from approximately ±1.8 deg. and 0.45 lb_f to ±8.5 deg. and 1.45 lb_f, respectively. The flutter test vane consumes only 1W of peak power at max. actuation frequency, drastically reducing the impact of electrical power supply lines on the modal mass of the wing. This paper describes the modeling, testing and evaluation of the adaptive flutter test vane and quantifies the implications on the current state of flight flutter testing.

Proceedings Article | 10 April 2010 Paper

Post-buckled precompressed (PBP) solid state adaptive rotor

Ronald Barrett, Ryan Barnhart

Proceedings Volume 7643, 764323 (2010) https://doi.org/10.1117/12.847344

KEYWORDS: Actuators, Unmanned aerial vehicles, Aerodynamics, Missiles, Solid state physics, Mechanics, Solid state electronics, Performance modeling, Resistance, Nulling interferometry

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This paper is centered on a new actuation philosophy executed on an old rotor design. An adaptive rotor employing twist-active piezoelectric root actuators was used as a testbed to investigate the new branch of structural mechanics devoted to low- and zero-net passive stiffness (ZNPS) structures. One of the more common methods to achieve zero net passive stiffnesses in structures is to employ "negative" springs: that is, mechanisms which when combined with the baseline structure null the passive stiffness of the total structural element. This paper outlines the application of such a system via a Post-Buckled Precompression (PBP) technique at the end of a twist-active piezoelectric rotor blade actuator. The basic performance of the system is handily modeled by using laminated plate theory techniques. A dual cantilevered spring system was used to increasingly null the passive stiffness of the root actuator along the feathering axis of the rotor blade. As the precompression levels were increased, it was shown that corresponding blade pitch levels also increased. The PBP cantilever spring system was designed so as to provide a high level of stabilizing pitch-flap coupling and inherent resistance to rotor propeller moments. Experimental testing showed pitch deflections increasing from just 8° peak-to-peak deflections at 650 V/mm field strength to more than 26° at the same field strength with design precompression levels. Dynamic testing showed the corner frequency of the linear system coming down from 63 Hz (3.8/rev) to 53Hz (3.2/rev). Thrust coefficients manipulation levels were shown to increase from 0.01 to 0.028 with increasing precompression levels. The paper concludes with an overall assessment of the actuator design and conclusions on overall feasibility.

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