Systems and methods are provided for applying cold spray erosion protection to an airfoil. One embodiment is a method for applying an abrasion coating to a fiber-reinforced composite substrate. The method includes applying a bond layer to the fiber-reinforced composite substrate by emitting, with a supersonic nozzle of a High Pressure Cold Spray (HPCS) system, a first gas stream including a first metal powder at a first speed below supersonic speed. The method further includes applying a cold spray deposit layer to the bond layer by emitting, with the supersonic nozzle, a second gas stream including a second metal powder at a second speed above supersonic speed.

Sounds are generated by an aerial vehicle during operation. For example, the motors and propellers of an aerial vehicle generate sounds during operation. Disclosed are systems, methods, and apparatus for actively adjusting the shape of a propeller blade of an aerial vehicle during operation of the aerial vehicle. For example, the propeller blade may have one or more joints that adjust to alter the shape of the propeller blade. The altered shape of the propeller blade causes the propeller to generate different frequencies of sound as it rotates. By altering multiple propeller blades of the aerial vehicle, the different sounds generated by the different propeller blades may effectively cancel or reduce the total sound generated by the aerial vehicle, and/or alter the total frequency generated.

Sounds are generated by an aerial vehicle during operation. For example, the motors and propellers of an aerial vehicle generate sounds during operation. Disclosed are systems, methods, and apparatus for actively adjusting the shape of a propeller blade of an aerial vehicle during operation of the aerial vehicle. For example, the propeller blade may have one or more joints that adjust to alter the shape of the propeller blade. The altered shape of the propeller blade causes the propeller to generate different frequencies of sound as it rotates. By altering multiple propeller blades of the aerial vehicle, the different sounds generated by the different propeller blades may effectively cancel or reduce the total sound generated by the aerial vehicle, and/or alter the total frequency generated.

Systems and methods to improve controllability of an aerial vehicle responsive to degraded operational conditions are described. For example, one or more propeller blades of an aerial vehicle may be modifiable between two or more configurations. The configurations may include a low torque configuration suitable for normal operational conditions, and a high torque configuration suitable for degraded operational conditions. Various aspects or portions of a propeller blade may be modified to increase torque generated by the propeller blade due to drag or air resistance. The additional generated torque may then be used as a source of additional torque to improve controllability of the aerial vehicle responsive to degraded operational conditions.

Systems and methods to improve controllability of an aerial vehicle responsive to degraded operational conditions are described. For example, one or more propeller blades of an aerial vehicle may be modifiable between two or more configurations. The configurations may include a low torque configuration suitable for normal operational conditions, and a high torque configuration suitable for degraded operational conditions. Various aspects or portions of a propeller blade may be modified to increase torque generated by the propeller blade due to drag or air resistance. The additional generated torque may then be used as a source of additional torque to improve controllability of the aerial vehicle responsive to degraded operational conditions.

This invention describes a rotating wing that provides lift to an aircraft and that is driven by autorotation. It is a naturally stable rotating wing as it does not generate torque and is very safe because it uses autorotation at all times to drive its blades. The design of the blades allows you to use the autorotation in two different ways. The first dependent on the airflow created by moving the aircraft from one place to another and which provides a cruise flight mode and the second independent of the aircraft's movement from one place to another to provide a static flight mode that includes the ability to take off and land vertically, as well as hover at a static point in the air.

A preceramic resin formulation comprising a polycarbosilane preceramic polymer, an organically modified silicon dioxide preceramic polymer, and, optionally, at least one filler. The preceramic resin formulation is formulated to exhibit a viscosity of from about 1,000 cP at about 25° C. to about 5,000 cP at a temperature of about 25° C. The at least one filler comprises first particles having an average mean diameter of less than about 1.0 μm and second particles having an average mean diameter of from about 1.5 μm to about 5 μm. Impregnated fibers comprising the preceramic resin formulation are also disclosed, as is a composite material comprising a reaction product of the polycarbosilane preceramic polymer, organically modified silicon dioxide preceramic polymer, and the at least one filler. Methods of forming a ceramic matrix composite are also disclosed.

A preceramic resin formulation comprising a polycarbosilane preceramic polymer, an organically modified silicon dioxide preceramic polymer, and, optionally, at least one filler. The preceramic resin formulation is formulated to exhibit a viscosity of from about 1,000 cP at about 25° C. to about 5,000 cP at a temperature of about 25° C. The at least one filler comprises first particles having an average mean diameter of less than about 1.0 μm and second particles having an average mean diameter of from about 1.5 μm to about 5 μm. Impregnated fibers comprising the preceramic resin formulation are also disclosed, as is a composite material comprising a reaction product of the polycarbosilane preceramic polymer, organically modified silicon dioxide preceramic polymer, and the at least one filler. Methods of forming a ceramic matrix composite are also disclosed.

A propeller having a plurality of blades extending radially outward from a hub, the blades forming a loop. Each loop having an intake portion, an exhaust portion and a tip portion extending radially outward from the hub and a gap between the intake root and the exhaust root. The tip portion of each of the blades is 30%-75% of the blade, the tip portion beginning at a first deviation from zero of the roll value and extending to 90 degrees, wherein roll value is zero in a plane parallel to the hub axis, and wherein the blades have a vertical angle between −45 degrees and 45 degrees throughout.

A propeller having a plurality of blades extending radially outward from a hub, the blades forming a loop. Each loop having an intake portion, an exhaust portion and a tip portion extending radially outward from the hub and a gap between the intake root and the exhaust root. The tip portion of each of the blades is 30%-75% of the blade, the tip portion beginning at a first deviation from zero of the roll value and extending to 90 degrees, wherein roll value is zero in a plane parallel to the hub axis, and wherein the blades have a vertical angle between −45 degrees and 45 degrees throughout.