Abstract: A rotor system for a reactive drive rotary wing maintains the rigidity of the rotor and eliminates play between flight controls and the rotor by mounting swashplate actuators to a flange rigidly secured to the mast. Apparatus and methods perform thermal management of the rotor in order to avoid bearing failure or loss of bearing preload. Methods include modulating the temperature of oil pumped over one or more of the mast bearing, swashplate bearing, and spindle bearing. The temperature of air passively or actively drawn through rotor may also be modulated to maintain bearing temperature within a predetermined range. The rotor includes structures for reducing pressure losses and drag on components due to air flow through the rotor. A rotor facilitates thermal management by oil and air flow.

Abstract: A method for equalizing rolling moments at high advance ratios is disclosed including impelling an aircraft in a forward direction at an airspeed by means of a thrust source and rotating a rotor of the aircraft at an angular velocity with respect to the airspeed effective to cause a positive total lift on each blade due to air flow over the blades in the retreating direction when the blade is moving in the retreating direction. The rotor includes an even number of blades placed at equal angular intervals around the rotor hub. One or both of cyclic pitch and rotor angle of attack are adjusted such that a rolling moment of the retreating blade due to reverse air flow is between 0.3 and 0.7 times a rolling moment on the advancing blade due to lift.

Abstract: An aircraft is disclosed having an engine and a propeller mounted to a fuselage. An empennage mounts to the aircraft and includes first and second horizontal stabilizers separated by a distance greater than the diameter of a stream tube of the propeller at the horizontal stabilizers. A rudder extends between the horizontal stabilizers and is positioned within the stream tube of the propeller. A bulkhead is positioned rearward from the cockpit and oriented perpendicular to a longitudinal axis of the airframe. A tailboom and engine are mounted to the airframe by means of the bulkhead having the engine mounted between the tailboom and a lower edge of the bulkhead. Landing gear may mount to the bulkhead proximate a lower edge thereof. Systems and methods redistribute fuel among laterally, vertically, and longitudinally opposed fuel tanks to maintain a center of gravity in a dynamically stable position.

Abstract: A rotor system is disclosed for a reactive drive rotary wing aircraft. Apparatus and methods are disclosed for mounting to the rotor hub certain controls, both electrical and mechanical, as well as fuel delivery for tipjets mounted to rotor blades. Air passively or actively drawn through rotor may feed the tipjets directly through the blades, while fuel and control is delivered along the blade to the tip thereof.

Abstract: Apparatus and methods are disclosed for manufacture of a composite rotor blade spar having non-uniform wall thickness. Tooling for manufacturing include a first mold defining a first mold surface and a second mold comprising a rigid layer and a heated layer secured to the rigid layer and defining a second mold surface. A plurality of heating elements embedded in the second mold are activated according to a plurality of different temperature progressions effective to cure portions of the uncured composite blade spar positioned between the first and second mold surfaces coextensive with each heating element of the plurality of heating elements. In some embodiments, the second mold defines a root portion and first and second branch portions. A shear web is placed between the first and second branch portions and is bonded to a blade spar skin surrounding the second mold during curing of the blade spar skin.

Abstract: A rotor blade having conduits for supporting control lines is disclosed. The control lines extend from a rotor hub to a tip jet mounted near a distal end of the rotor blade. The conduits mount within leading and trailing edge fairings mounted to a blade spar. The conduits may be supported by bulkheads secured at discrete locations along the blade spar and secured to the leading and trailing edge fairings. The conduits may also be secured to support webs secured to the leading or trailing edge fairing and extending longitudinally therealong. The conduit may have a tapered inner surface and a tapered fitting may secure to the control line to engage the tapered inner surface.

Abstract: A rotor blade assembly is disclosed including a blade spar having a duct extending therethrough and having upper and lower surfaces. A mounting structure is secured to the blade spar and defines a fluid path in fluid communication with the duct. The mounting structure likewise has upper and lower surfaces. A tip jet is secured to the mounting structure in fluid communication with the fluid path. The blade spar and mounting structure abut one another at a joint and the upper surfaces of the blade spar and mounting structure lie on a common airfoil contour extending across the joint. The lower surfaces of the blade spar and mounting structure also lie on the common airfoil contour. One or both of the blade and mounting structure include a composite material. The mounting structure may include two portions secured to one another having a distal portion of the blade spar captured therebetween.

Abstract: A rotorcraft is disclosed. The rotorcraft may include an airframe, at least one engine connected to the airframe, and a rotor connected to the airframe. The rotor may include a hub, a rotor blade, and a feathering spindle connecting the rotor blade to the hub. The rotorcraft may further include a flow of oil passing proximate the feathering spindle. The flow of oil may cool the feathering spindle during take off and landing of the rotorcraft. Additionally, the flow of oil may heat the feathering spindle during travel of the rotorcraft at altitude.

Abstract: A rotor blade having a detachable fairing is disclosed. The rotor blade includes leading and trailing edge fairings secured to the blade spar and one or more control lines extending between of the fairings and the blade spar. A detachable fairing extends from one or both of the leading and trailing edge fairings toward one of the distal and proximal ends of the blade spar. The detachable fairing and blade spar form an airfoil contour. The detachable fairing may secure to a tip jet attachment fitting at a distal end of the blade spar. A mounting structure including upper and lower plates may secure near a proximal end of the blade spar and the detachable fairing may secure to both the upper and lower plates to form all or part of an airfoil contour. The mounting structure may include a spherical seat engaging a spherical surface of a hub shroud.

Abstract: A rotor system is disclosed for a reactive drive rotary wing aircraft. Apparatus and methods are disclosed for maintaining the rigidity of the rotor and eliminating play between flight controls and the rotor by mounting swashplate actuators to a flange rigidly secured to the mast. Methods are disclosed for modulating the temperature of oil pumped over one or more of the mast bearing, swashplate bearing, and spindle bearing. The temperature of air passively or actively drawn through rotor may also be modulated to maintain bearing temperature within a predetermined range. Structures for reducing pressure losses and drag on components due to air flow through the rotor are also disclosed. A rotor facilitating thermal management by oil and air flow is also disclosed. Surfaces interfacing between the swashplate and the mast and between control rods and the swashplate or pitch horn may bear a solid lubricant layer.

Abstract: Apparatus and methods for controlling yaw of a rotorcraft in the event of one or both of low airspeed and engine failure are disclosed. A yaw propulsion device, such as an air jet or a fan may be used. A pneumatic fan may be driven by compressed air released into a channel surrounding an outer portion of the fan. Power for the yaw propulsion device and other system may be provided by a hydraulic pump and/or generator engaging the rotor. Low speed yaw control may be provided by auxiliary rudders positioned within the stream tube of a prop. The auxiliary rudders may one or both of fold down and disengage from rudder controls when not in use. Apparatus for generating horizontal lift imbalance induced a tail boom positioned within the downwash of a rotor may also be used, including compressed air vents or lateral or trailing edge flaps.

Abstract: A rotor system of a reactive drive rotary wing maintains rigidity and stiffness and resists slack and backlash by mounting swashplate actuators to a flange rigidly secured to the mast, and may be monolithic therewith. A mast tilt actuator and a mast pivot may secure to the mast flange, with vibration suppressors. A shroud may provide a sealed fluid path for airflow therethrough encircling portions of the rotor hub and restricting airflow between the rotor hub and shroud. A rotor cavity, in fluid communication with blade ducts (hollow portions of the blade spars), and either or both contoured to reduce pressure losses, may assist in temperature control, and may feed into tip jets on the blades.

Abstract: A method and apparatus for enabling high speed flight in a rotorcraft are disclosed. The method may include executing a flight with a rotorcraft. The flight may include a first portion and second portion ordered sequentially. During the first portion, the rotorcraft may be flown with the rotor exclusively in autorotation. Once sufficient airspeed is obtained, the flight may transition to the second portion. Wherein, substantially all of the weight of the rotorcraft may be supported by one or more fixed wing surfaces of the rotorcraft. Thus, during the second portion, the rotor may be completely unloaded. To keep the rotor stable by turning, the rotor may be powered during the second portion by an engine of the rotorcraft by way of a prerotation system.

Abstract: A rotorcraft may include an airframe and a rotor connected to the airframe. The rotor may include a plurality of blades defining ducts along the length thereof and vents in fluid communication with the ducts. Flow from through the vents may be controlled by valves with piezoelectric actuators. The valves may be adjusted to achieve a lift profile suited for an operational mode such as vertical, autorotative, or unloaded flight. The lift profile may vary along the length of the blade and may vary cyclically with rotation of the blade. The lift profile may be chosen to approximate a figure of merit for the rotor suitable for a given operational mode.

Abstract: A method and apparatus for reducing roll of rotorcraft landing in autorotation may include executing a flight with a rotorcraft. The flight may include first, second, and third portions ordered sequentially. During the first portion, the rotorcraft may be flown with the rotor exclusively in autorotation. During the second portion, the rotorcraft may be flown with the rotor powered at least partially by an engine of the rotorcraft, which may increase the rotational speed of the rotor. During the third portion, the rotorcraft may be flown with the rotor exclusively in autorotation. The flight and the third portion may terminate simultaneously with a touch down of the rotorcraft. Kinetic energy stored in the rotor during the second portion, during the third portion, bring the ground speed of the rotorcraft to substantially zero before touching down.

Abstract: A method and apparatus for reducing flapping loads imposed on a rotor are disclosed. The method may include flying a rotorcraft comprising an airframe, a rotor, a mast extending to connect the rotor to the airframe, a tilt mechanism, at least one sensor, and a computer system. The computer system may obtain in real time, from the at least one sensor, data characterizing at least one flapping load experienced by the rotor during the flying. Using the data, the computer system may issue at least one command to the tilt mechanism. In response to the command, the tilt mechanism may reorient the mast with respect to the airframe. This reorienting may lower the flapping load experienced by the rotor.

Abstract: A method and apparatus for optimized crossing of natural frequencies of a rotorcraft rotor are disclosed. The method may include flying a rotorcraft comprising an airframe, a rotor, a mast extending to connect the rotor to the airframe, a tilt mechanism, and a computer system. The computer system may identify during the flying, an impending crossing of a natural frequency of the rotor. In preparation for the crossing, the computer system may issue at least one command to the tilt mechanism. In response to the command, the tilt mechanism may reorient the mast with respect to the airframe. That reorientation quickly results in a change to the rotational speed of the rotor, moving it quickly across the natural frequency. The reorientation may also prevent the rotor from experiencing any significantly deleterious flapping loads during the crossing of the natural frequency.

Abstract: A rotor system is disclosed for a reactive drive rotary wing aircraft. Apparatus and methods are disclosed for maintaining the rigidity of the rotor and eliminating play between flight controls and the rotor by mounting swashplate actuators to a flange rigidly secured to the mast. Methods are disclosed for modulating the temperature of oil pumped over one or more of the mast bearing, swashplate bearing, and spindle bearing. The temperature of air passively or actively drawn through rotor may also be modulated to maintain bearing temperature within a predetermined range. Structures for reducing pressure losses and drag on components due to air flow through the rotor are also disclosed. A rotor facilitating thermal management by oil and air flow is also disclosed. Surfaces interfacing between the swashplate and the mast and between control rods and the swashplate or pitch horn may bear a solid lubricant layer.

Abstract: The rotorcraft may include an airframe, at least one engine connected to the airframe, and a rotor connected to the airframe. The rotor may include a hub, a rotor blade, and a feathering spindle connected to the hub. The rotor blade may have a root and a tip and form a conduit extending in the radial 5 direction from the root to the tip. The root may comprise a wall forming a hollow circular cylinder. The hollow circular cylinder may form a portion of the conduit. A plurality of bolts may be distributed circumferential within the wall of the root. The plurality of bolts may extend in the radial direction from the wall of the root to secure the rotor blade to the feathering 10 spindle.

Abstract: Apparatus and methods for controlling yaw of a rotorcraft in the event of one or both of low airspeed and engine failure are disclosed. A yaw propulsion provides a yaw moment at low speeds. The yaw propulsion device may be an air jet or a fan. A pneumatic fan may be driven by compressed air released into a channel surrounding an outer portion of the fan. The fan may be driven by hydraulic power. Power for the yaw propulsion device and other system may be provided by a hydraulic pump and/or generator engaging the rotor. Low speed yaw control may be provided by auxiliary rudders positioned within the stream tube of a prop. The auxiliary rudders may one or both of fold down and disengage from rudder controls when not in use.