Biomimetic mechanism for micro aircraft

A biomimetic pitching and flapping mechanism including a support member, at least two blade joints for holding blades and operatively connected to the support member. An outer shaft member is concentric with the support member, and an inner shaft member is concentric with the outer shaft member. The mechanism allows the blades of a small-scale rotor to be actuated in the flap and pitch degrees of freedom. The pitching and the flapping are completely independent from and uncoupled to each other. As such, the rotor can independently flap, or independently pitch, or flap and pitch simultaneously with different amplitudes and/or frequencies. The mechanism can also be used in a non-rotary wing configuration, such as an ornithopter, in which case the rotational degree of freedom would be suppressed

Method and System for Determining Relative Displacement and Heading for Navigation

A system and method for determining a location of a mobile object is provided. The system determines the location of the mobile object by determining distances between a plurality of sensors provided on a first and second movable parts of the mobile object. A stride length, heading, and separation distance between the first and second movable parts are computed based on the determined distances and the location of the mobile object is determined based on the computed stride length, heading, and separation distance

Investigation of the use of uniaxial comb-shaped Galfenol patches for a guided wave-based magnetostrictive phased array sensor

This paper investigates the use of uniaxial comb-shaped Fe-Ga alloy (Galfenol) patches in the development of a Magnetostrictive Phased Array Sensor (MPAS) for the Guided Wave (GW) damage inspection technique. The MPAS consists of six highly-textured Galfenol patches with a preferred orientation and a Hexagonal Magnetic Circuit Device (HMCD). The Galfenol patches individually aligned to distinct azimuthal directions were permanently attached to a thin aluminum plate specimen. The detachable HMCD encloses a biasing magnet and six sensing coils with unique directional sensing preferences, equivalent to the specific orientation of the discrete Galfenol patches. The preliminary experimental tests validated that the GW sensing performance and directional sensitivity of the Galfenol-based sensor were significantly improved by the magnetic shape anisotropy effect on the fabrication of uniaxial comb fingers to a Galfenol disc patch. We employed a series of uniaxial comb-shaped Galfenol patches to form an MPAS with a hexagonal sensor configuration, uniformly arranged within a diameter of 1”. The Galfenol MPAS was utilized to identify structural damage simulated by loosening joint bolts used to fasten the plate specimen to a frame structure. We compared the damage detection results of the MPAS with those of a PZT Phased Array Sensor (PPAS) collocated to the back surface of the plate. The directional filtering characteristic of the Galfenol MPAS led to acquiring less complicated GW signals than the PPAS using omnidirectional PZT discs. However, due to the detection limit of the standard hexagonal patterned array, the two array sensors apparently identified only the loosened bolts located along one of the preferred orientations of the array configuration. The use of the fixed number of the Galfenol patches for the MPAS construction constrained the capability of sensing point multiplication of the HMCD by altering its rotational orientation, resulting in such damage detection limitation of the MPAS

Guided wave phased array sensor based on a Galfenol flake-epoxy composite patch with unique circular comb pattern

This paper investigates a study of the use of a Fe-Ga alloy (Galfenol) flake-epoxy composite patch with a circular comb shape for Magnetostrictive Phased Array Sensors (MPAS) used for Structural Health Monitoring (SHM) applications based on the ultrasonic Guided Wave (GW) inspection technique. Galfenol materials have demonstrated a variety of beneficial properties for transducer developments such as high magneto-mechanical coupling, low hysteresis loss, moderate magnetostriction and saturation magnetization, and steel-like manufacturability. However, typical Galfenol materials exhibit anisotropic magnetostrictive characteristics that are disadvantageous for a wide range of applications to the GW SHM, especially phased array technology. To overcome the limitation of the Galfenol materials for the service of the GW phased array approach, we developed the Galfenol composite patch based on the circular comb pattern to improve the directional GW sensing performance using the shape anisotropic effect of the magnetostrictive material. The GW MPAS used in this work consists of a magnetostrictive composite patch directly bonded to a waveguide structure and a non-contact and azimuthally rotatable Hexagonal Magnetic Circuit Device (HMCD) including a biasing magnet and six sensing coils with predetermined directional sensing preferences. Although the GW signals obtained from the MPAS using the Galfenol composite patch were weak, the experimental results validated that the proposed MPAS was capable of detecting GWs using the flake-epoxy composite material and exhibited the obvious directional sensing characteristics. There are only six sensing coils in the HMCD, but the MPAS can acquire additional GW signal data in the Galfenol composite patch by simply altering the rotational orientation of the HMCD, leading to effective array imaging results by suppressing unwanted shadow images induced by the side lobe effect of the directional wavenumber filtering method

Approximate Performance of Periodic Hypersonic Cruise Trajectories for Global Reach

This paper develops the analytical framework to compare the approximate performance of periodic hypersonic cruise trajectories with previously proposed hypersonic trajectory profiles for global reach. Specifically, range, \DeltaV and payload carrying capacity are evaluated for various trajectory types to illustrate the enhanced performance achieved by flying periodic hypersonic cruise trajectories with existing hypersonic vehicle aerodynamic, propulsion, and structures technology. Analytical results reveal that periodic hypersonic cruise trajectories achieve better fuel consumption savings over long distances (ß20,000 km) than other trajectory types proposed for high-speed flight. A 20+% improvement in fuel consumption savings is possible for a Mach 10 vehicle with a modest L/D=4, and a curve-fitted rocket-based combined cycle engine model. Nomenclature a = Speed of sound A = Area Research Engineer y Assistant Professor, Senior Member AIAA. z Graduate Research Assistant, Stude..

Dynamic Stability of Mission Oriented Hypersonic Waveriders

The longitudinal dynamic stability characteristics of a caret-wing/wedge (CWW) waverider, without engine integration, is explored. Hypersonic piston theory is used to derive analytical stability derivatives and coefficients. These stability coefficients are incorporated into the linearized equations of motion for longitudinal dynamics. The stability and control characteristics of the system dynamics are investigated over a variety of mission trajectories including ascent, steady-state cruise and periodic cruise. Nomenclature A = Area a = Wedge width a sub = Speed of sound at subscript section b = Caret-wing width c = Caret-wing width ¯ c = Caret-wing width F = Force vector I y = Y-axis moment of inertia l t = X-axis length to tail quarter chord M = Mach number n = Surface normal vector p = X-axis rotation rate p sub = Pressure q = Y-axis rotation rate q sub = Dynamic pressure r = Z-axis rotation rate r = Position vector S = Surface area Graduate Research Assistant,..

Moveable Cowl Control for Increased Hypersonic Performance

A novel concept of a moveable cowl is introduced for improving the performance of integrated hypersonic waverider designs. These vehicle designs are typically computed at one design Mach number. Thus, off-design performance suffers because of flow spillage at the engine inlet. A moveable cowl can be used to track shock on lip conditions to capture off-design flow. In this paper the concept of a moveable cowl is discussed to control local and global effects of hypersonic waveriders. Specifically, a simple caret-wedge configuration is used to study the on/off design performance and the pitch control sensitivity of a moveable cowl. Nomenclature M = Mach number P o = Total Pressure r = Cowl lip radius T = Temperature T o = Total Pressure x o = Initial x-coordinate of cowl lip y o = Initial y-coordinate of cowl lip fi = Shock angle fl = Specific heat ratio ffi = Shock stand-off distance = Sonic line angle ` = Flow Deflection Angle ` ffl = Sum of previous flow deflection angles..

Approximate Performance of Periodic Hypersonic Cruise Trajectories for Global Reach

This paper develops the analytical framework to compare the approximate performance of periodic hypersonic cruise trajectories with previously proposed hypersonic trajectory profiles for global reach. Specifically, range, \DeltaV and payload carrying capacity are evaluated for various trajectory types to illustrate the enhanced performance achieved by flying periodic hypersonic cruise trajectories with existing hypersonic vehicle aerodynamic, propulsion, and structures technology. Analytical results reveal that periodic hypersonic cruise trajectories achieve better fuel consumption savings over long distances ( 20,000 km) than other trajectory types proposed for high-speed flight. A 20+% improvement in fuel consumption savings is possible for a Mach 10 vehicle with a modest L/D=4, and a curve-fitted rocket-based combined cycle engine model. Nomenclature a = Speed of sound A = Area A = Vector term c = Exhaust velocity CD = Drag coefficient CL = Lift coefficient D = Drag E = Range/Mass..