Abstract: A transmission includes a first component and a second component which are journaled for rotation relative to each other, and a locking mechanism for rotationally locking the first component and the second component relative to each other in a predetermined mutual rotation position. The locking mechanism includes a sleeve and a dog clutch, the sleeve being rotationally locked relative to the first component and the dog clutch being rotationally locked relative to the second component, the sleeve and the dog clutch being axially displaceable relative to each other for engagement of the sleeve and the dog clutch such that the first component and the second component are rotationally locked relative to each other, the sleeve and the dog clutch being engageable only in a mutual rotation position corresponding to the predetermined mutual rotation position of the first component and the second component.

Abstract: An unmanned aerial vehicle with deployable components (UAVDC) may comprise a foldable propeller blade with a locking mechanism. Foldable propeller blades may have a stowed configuration and a deployed configuration relative to the UAVDC, and the foldable propeller blades may pivot about a hinge to move between configurations. In the deployed configuration, the foldable propeller may experience forward folding forces acting upon it. The locking mechanism may lock the foldable propeller blade in the deployed configuration. The locking mechanism may keep the foldable propeller locked into place to prevent forward folding tendency.

Abstract: An aircraft includes a fuselage carrying a nacelle of the aircraft offset relative to a wing of the aircraft. The nacelle forms an air inlet fairing of a propulsion assembly. The nacelle includes a lower wall and an upper wall delimiting together a height of the nacelle. The lower wall includes an air inlet edge being contiguous with a trailing edge of the wing.

Abstract: An example method of manufacturing a wing includes providing a wing frame. The wing frame includes a primary spar, a drag spar, a plurality of transverse frame elements having at least one spar joiner, and a plurality of mounting elements. The primary spar is coupled to the drag spar via the at least one spar joiner. The method further includes placing the wing frame into a mold, wherein the mold defines a shape of the wing. The method also includes injecting the mold with an air-filled matrix material, such that the air-filled matrix material substantially encases the wing frame and fills the defined shape of the wing, and such that the plurality of transverse frame elements provide torsional rigidity to the wing.

Abstract: Systems, devices, and methods for stopping the rotation of propellers used in unmanned aerial vehicles (UAV) such as drones are disclosed. The propellers are stopped in response to sensing human touch on a surface of the UAV using capacitive sensors.

Abstract: An aircraft includes a fuselage, a wing disposed above the fuselage, a pylon connecting the wing to the fuselage, and a plurality of internal combustion engines housed in the fuselage. The pylon vertically traverses the fuselage and is fixed to an upper portion and a lower portion of the fuselage. Among the plurality of internal combustion engines, a first internal combustion engine and a second internal combustion engine are disposed bilaterally symmetrically about the pylon and are fixed to the pylon.

Abstract: The invention relates to a module of a turbomachine of longitudinal axis X, the module comprising: ?—a rotary casing (31) that rotates about the longitudinal axis and bears a propeller (2; 20, 21, 22) which is provided with a plurality of blades (32); ?—a fixed casing (48) comprising a cylindrical wall (49) extending between an inner wall (40) and an outer wall (41) of the rotary casing (31); and, ?—a system (30) for changing the pitch of the blades of the propeller, mounted around the fixed casing and comprising: a control means (55) comprising a movable body (57) that is able to move axially on said fixed casing, at least one load transfer bearing (56) comprising an inner ring (65) that is connected to the movable body (57), and an outer ring (66); and a connection mechanism (61) for connecting the outer ring (66) to the blades of the propeller.

Abstract: A propeller apparatus of an air mobility includes a housing having an inner space, where multiple slits are formed along a circumferential surface of the housing to extend in a vertical direction; a driving unit having connection portions formed to match respective ones of the slits in the housing; multiple link units configured to match the respective ones of the slits in the housing, where the link units are rotatably connected to the connection portions, respectively, of the driving unit; and multiple wing units configured to be rotated in a manner of being linked with the link units, which rotate when the driving unit moves up and down, thereby being folded to or deployed from the housing. The propeller apparatus is configured to prevent an accident due to scattering of a propeller when the air mobility falls, and to improve space utilization during storage of the air mobility.

Abstract: An aircraft propulsion system comprises a vertical lift propulsor mounted within a wing of the aircraft. The vertical propulsor comprises an electric motor comprising a rotor mounted to a plurality of propulsor blades, the motor further comprising a stator. The rotor is provided radially outwardly of the stator.

Abstract: An accelerating ducted propeller system for propelling boats offers enhanced performance, having the front end of the nozzle disposed at a radial distance (H) between 0.045D and 0.082D from the inner radius of the nozzle, where D is the inner diameter of the nozzle. The front end of the chord of the axial profile of the nozzle has a larger radius than the rear end of the chord with respect to the axis of rotation of the propeller. The inner surface of the nozzle at the axial distance (J) of 0.025D from the rear end of the output edge of the nozzle is at a radial distance from the inner radius of the nozzle of more than 0.0040D and less than 0.0300D. The radial difference between the inner radius of the nozzle and the outer radius of the profile of the nozzle is less than 0.092D.

Abstract: Systems, apparatuses, and methods are provided herein for providing aerial animal food delivery. In one embodiment, a system for providing aerial animal food delivery comprises: an unmanned aerial vehicle, an animal food container coupled to the unmanned aerial vehicle, the animal food container being configured to hold animal food during transport by the unmanned aerial vehicle, and a central computer system communicatively coupled to the unmanned aerial vehicle, the central computer system being configured to: instruct the unmanned aerial vehicle to travel to a service location at a service time with the animal food container and instruct a release of the animal food from the animal food container in an unpackaged form at the service location such that the animal food is accessible to and edible by one or more animals upon release.

Abstract: A propeller which can be folded and stowed in compact form and then deployed for powered flight is disclosed. The deployable propeller has two or more blades, and each blade is composed of multiple segments which are disengaged when stowed and then interlock when deployed to form an efficient blade. The segmented deployable propeller retains all effective area to the spinner radius.

Abstract: A propeller includes a hub coaxially surrounding a longitudinal axis. A ring shroud coaxially surrounds the longitudinal axis and is spaced radially from the hub. At least one propeller blade is fixedly attached to both the hub and ring shroud and extends radially therebetween for mutual rotation therewith. At least one stub blade has a first stub end radially spaced from a second stub end. The first stub end is fixedly attached to a selected one of the hub and ring shroud. The second stub end is cantilevered from the first stub end and is radially interposed between the first stub end and the selected one of the hub and ring shroud.

Abstract: A portable speaker system includes: a waterproof enclosure; a wireless communication element enclosed within the waterproof enclosure, the wireless communication element able to receive audio data from a mobile device; a pair of speakers enclosed within the waterproof enclosure that are able to generate an audio output based on the audio data received from the mobile device; and a set of connection ports located within a first recessed area of the waterproof enclosure, the first recessed area including a flexible cover that is able to expose the first recessed area when in an open position and form a waterproof seal with the waterproof enclosure when in a closed position.

Abstract: An aeronautical vehicle that rights itself from an inverted state to an upright state has a self-righting frame assembly has an apex preferably at a top of a central vertical axis. The apex provides initial instability to begin a self-righting process when the vehicle is inverted on a surface. A lift and stabilization panel extends across an upper portion of said frame to provide lift, drag and/or stability. A propulsion system can be located within a central void of the frame assembly and oriented to provide a lifting force. An electronics assembly is also carried by the self-righting frame for receiving remote control commands and is communicatively interconnected to the power supply for remotely controlling the aeronautical vehicle to take off, to fly, and to land on a supporting surface. The frame provides self-righting functionality and protection of elements carried therein.

Abstract: An aircraft (40). The aircraft (40) comprises a propulsion system comprising a pair of internal combustion engines (10) each driving an electrical power generator (56), each electrical power generator (56) being electrically coupled to a plurality of electrically driven propulsors (46). The propulsors (46) are located forward of a leading edge (45) of the wings (44) such that an airstream generated by the propulsors flows over the wings (44) in use. Each internal combustion engine (10) and electrical generator (56) is mounted on a respective wing (44) outboard of a centre of thrust (70) of the propulsors (46) on that wing (44).

Abstract: An airplane comprises a twin-deck fuselage in which an upper deck support structure is utilized for carry-through of a mid-mount main wing box. The main landing gear of the airplane is mounted to the fuselage and is stowed in a non-pressurized area below the main wing box (enabled due to an optimized wing box geometry). A pressurized passageway/cargo/galley complex separates the main landing gear box and the main wing box. The upper deck is continuous, while the lower deck is separated by the wheel wells into two distinct fore and aft areas (for either cargo or passengers). The airplane further comprises an integrated vertical fin and an aft-extended pressurized deck area for reduced double-deck wetted area. More specifically, the double-deck pressurized fuselage structure is extended to form a blending structure to which a structural box of the vertical fin is attached.

Abstract: Aircraft comprising a single wing suspended under a closed sided chassis. The wing spar is mounted to the sides that enclose and channel the airflow over and under the wing to provide lift. Airflow is provided by a source located in front of the wing by means of either propeller, ducted fan or similar devise. Engines mounted on a rotational engine mount can provide downward thrust to lift front of craft to obtain an angle great enough for lift-off Once aircraft has sustained-angle for lift off engine(s) rotate to produce airflow parallel to wing for flight. Rudders mounted behind the air source and prior to the wing provide steering.

Abstract: An airplane comprises a twin-deck fuselage in which an upper deck support structure is utilized for carry-through of a mid-mount main wing box. The main landing gear of the airplane is mounted to the fuselage and is stowed in a non-pressurized area below the main wing box (enabled due to an optimized wing box geometry). A pressurized passageway/cargo/galley complex separates the main landing gear box and the main wing box. The upper deck is continuous, while the lower deck is separated by the wheel wells into two distinct fore and aft areas (for either cargo or passengers). The airplane further comprises an integrated vertical fin and an aft-extended pressurized deck area for reduced double-deck wetted area. More specifically, the double-deck pressurized fuselage structure is extended to form a blending structure to which a structural box of the vertical fin is attached.

Abstract: The present invention features a screw propeller system for use in a machine including a watercraft or an aircraft. The system features two or more screw propellers installed in the machine. Each screw propeller comprises an axle with a spiral blade disposed on the axle, and a tube hub. A differential and disc-brake device is operatively connected to each the first screw propeller and the second screw propeller. The differential and disc-brake device functions to steer the machine.

Abstract: Systems, method, devices and apparatus are provided for reducing drag and increasing the flight efficiency characteristics of aircraft and airships including hybrid aircraft utilizing distributed boundary layer control and propulsion devices. Boundary layer control includes passive systems such as riblet films and boundary layer propulsion devices having a divided and distributed propulsion system disposed in the curved aft sections of aircraft and airships including hybrid aircraft susceptible to boundary layer drag due to degree of curvatures, speed and density of the surrounding air. Distributed propulsion devices include constructing propellers and riblets from shape memory alloys, piezoelectric materials and electroactive polymer (EAP) materials to change the shape and length of the distributed propulsion device.

Abstract: The system includes a keel fitting that can be rigidly attached directly to the keel of the hang glider. It also includes two elongated frame members symmetrically mounted on opposite sides of the keel fitting. At least one electrical motor is mounted on each frame member and there are at least two propellers, each in driving engagement with a corresponding one of the electrical motors. The system further includes an electrical power unit mounted on the back of the pilot. The electrical power unit includes at least one battery and a pilot-actuated control circuit to vary the electrical power supplied to the electrical motors. The system gives the pilot the capability of taking off from a flat terrain. Once airborne, the system is not operated and the hang glider can then be used as an unpowered one.

Abstract: A propeller for an aircraft is disclosed. The propeller has an odd number of unequally circumferentially spaced blades. The propeller may be provided as part of a contra-rotating propeller arrangement and/or aft of a pylon on an aircraft. The propeller has been found to reduce noise levels and to be efficient.

Abstract: An aircraft with a fuselage and two aerodynamic wings, which each accommodate at least two propeller drives spaced a apart from each other in the wingspan direction, each with a propeller rotational axis, wherein the aircraft has a controller for activating the propeller drives, wherein in one operating mode of the controller for generating propulsion, the propeller drives are activated in such a way that the outer section of a propeller secured to the respective propeller rotational axis is moved from the top down on the side facing the fuselage.

Abstract: A vehicle including at least one bladder for containing a fuel as liquid and gas at a predetermined pressure, with a bladder outlet arranged to releasing fuel from the bladder and to maintain the fuel in the bladder at the predetermined pressure, the fuel provides thrust to the vehicle upon combustion, the fuel-filled bladder providing initial structural integrity of the vehicle. In an exemplary embodiment, the vehicle is an unmanned anal vehicle. A combustion chamber and thermoelectric conversion module can generate electricity for a propellor and battery from the fuel supply. Internal vapor pressure is maintained until the fuel bladder is empty.

Abstract: Methods for minimizing the effects of pylori induced disturbances of the airflow at the propeller blades (2) of propeller propulsion devices (3) attached to an aircraft component (5) by means of upstream pylons (4), comprising steps of injecting fluid on the zone of the propeller blades (2) from the rear part of said pylons (4) for minimizing the effects of said disturbances detected through the values of a first set of parameters such acoustic pressure and vibration in the aircraft structure and vibration in the propeller blades (2) that are obtained continuously or according to models linked to one or more parameters of a second set of parameters indicative of the aircraft flight conditions such as flight altitude, flight speed propulsion power, propeller rotation speed obtained from a tachometer signal, ambient temperature of the air. The invention also refers to systems for implementing said methods.

Abstract: The invention relates to a segmented aerial vehicle with gasbags filled with an energy medium. It refers in particular to an aerial vehicle having interlinked gasbags and/or one big gasbag. This one gasbag or these interlinked gasbags are filled with an energy medium the specific weight of which is approximately the one of air. The energy medium of the gasbags provides energy to the eccentrically placed controllable engines fixed at the segments. The vector thrust produced by the engines and by the vehicle's envelope under excess compression provide sufficient dynamic lift to have the proposed invention fly in a stable and controllable way all in carrying a defined payload, Inside segmented interconnected airbags are placed interconnected segmented gasbags.

Abstract: A roadable aircraft may be registered and driven as a motorcycle on the roadways, does not require that any parts be “left behind” at the airport when configuring to roadable use and does not require removing portions of the aircraft and towing them behind. A foldable and collapsible wing comprises a number of wing ribs, which are hinged to a main forward spar. To fold for road usage, the wing ribs fold about a hinge fitting to collapse against the wing spar. To maintain tension on the wing skin (to prevent flutter) tensioning bladder(s) may be used to keep the fabric taut. Once retracted and folded, the wings align with tail booms to form a compact and aerodynamic package. The ductless fan may be provided with a center-mounted extraction fan ducted to inlets along the fuselage to draw low energy air in toward the fuselage and thus prevent boundary layer separation.

Abstract: A propulsor apparatus for a mobile platform, for example an aircraft is provided. The propulsor apparatus includes an aerodynamically shaped propeller duct that houses at least a portion of a turboprop engine, and fully houses a propeller driven by the engine. Inside the propeller duct is a circumferential ring that closely surrounds the propeller such that only a small clearance is provided between the outermost tips of the propeller blades and an inner surface of the circumferential ring. The circumferential ring includes sound deadening material that attenuates noise generated by the tip vortices created at the outermost tips of the propeller blades. The propeller duct and circumferential ring are supported by a plurality of structural rods that couple to structure of the mobile platform, for example to the spars within a wing of an aircraft. The apparatus and method significantly reduces the noise associated with a turboprop engine.

Abstract: Various embodiments of an aerial vehicle with propulsion system and a protective frame is disclosed. The propulsion system has an air intake side and air outlet side. The protective frame surround both the intake and outlet side of the propulsion system to protect at least some components of the propulsion system from obstacles and other aerial vehicles. In some embodiments, the propulsion system includes one or more rotors or propellers. In some embodiments, protective frame also surrounds the radial ends of the rotor or propeller.

Abstract: The present invention pertains to a solar cell module comprising at least one photovoltaic element encapsulated between a front layer on its light receiving surface side and a back layer, said front layer comprising at least one layer comprising a tetrafluoroethylene (TFE) polymer [polymer (F)], said polymer (F) comprising: recurring units derived from TFE; and from 15 to 25% wt of recurring units derived from at least one perfluoromonomer [monomer (CM)] chosen among: (i) perfluoroalkylvinylethers complying with formula CF2?CFORf1, in which Rf1 is a C1-C6 perfluoroalkyl, e.g. —CF3, —C2F5, —C3F7; and/or (ii) perfluoro-oxyalkylvinylethers complying with formula CF2?CFOX0, in which X0 is a C1-C12 perfluorooxyalkyl having one or more ether groups, like perfluoro-2-propoxy-propyl; and (iii) mixtures thereof. Still objects of the invention are a process for the manufacture of the solar cell module as above defined and its use for producing current to external sources, e.g. for powering a fixed-wing aircraft.

Abstract: An aircraft comprises an airframe, an electric propulsion system, a number of battery pods, and an engagement system. The number of battery pods has a physical connector system. The engagement system is attached to the airframe and is capable of engaging the physical connector system to connect the number of battery pods to the airframe.

Abstract: An unmanned air vehicle for military, land security and the like operations includes a fuselage provided with foldable wings having leading edge flaps and trailing edge ailerons which are operable during ascent from launch to control the flight pattern with the wings folded, the wings being deployed into an open unfolded position when appropriate. The vehicle is contained within a pod from which it is launched and a landing deck is provided to decelerate and arrest the vehicle upon its return to land.

Abstract: According to the present invention, at least the symmetric external parts (9G, 9D) of the front lower wing (9) have a sweep forward (?a), the lift generated by the rear upper wing (10) is greater than the lift generated by the front lower wing (9), the rear upper wing (10) is in direct contact with the rear upper parts of the fuselages (2G, 2D), and the propulsion system (11, 12, 13) comprises at least one turboprop engine having at least one propeller and is carried by the internal part (10I) of the rear upper wing (10), the axis.(l-l) of the propulsion system lying in the longitudinal mid-plane (L-L).

Abstract: An engine for use in operating an aircraft is disclosed, the engine comprising a decomposition chamber configured to decompose into at least one combustible constituent element a first chemically unstable substance in the presence of a catalyst, wherein the decomposition of the first chemically unstable substance releases a first amount of heat; a first turbine configured to accept the constituent elements and the first amount of heat from the decomposition chamber and thereby rotate; a compressor rotationally connected to the first turbine, and configured to compress air when the first turbine rotates; and a combustion chamber configured to accept the compressed air and constituent elements and combust the combination, substantially regardless of an altitude above sea level and ambient air pressure, and output the combustion products into a power turbine, causing it to rotate, whereby the rotation of the first turbine and/or the power turbine rotate a propeller rotationally coupled to the first and power tur

Abstract: A system for utilizing the slower boundary layer and aircraft wake to improve propulsive efficiency for buoyant and semi-buoyant aircraft is described. By ingesting air through an annular inlet located at the aft portion of the aircraft and accelerating it via an embedded ducted fan, maximum propulsive efficiency may be obtained, without the excessive losses due to viscous drag forces experienced in vehicles utilizing long ducts drawing air from inlets placed further forward. The method also reduces the acoustic signature when compared to unshrouded stem propellers or freestanding ducts.

Abstract: Single engine aircrafts, spot light, seaplanes, ultra-light planes, gyro-planes, power parachutes, trikes, airship etc commonly use fixed pitch low efficiency propellers that generate unbalancing torque. Pilots need to make offset turning to anti-torque. The subject novel anti torque coaxial counter rotation Bi-Prop Rotor fill out the empty of such variable and reversible thrust anti-torque propulsion device. The Bi-Prop Rotor comprises an on axis driving compact unobvious gear box; 2 sets multiple blades prop-rotors with variable pitch push rods and bearing-plate assemblies, co-axial tandem mounted at both sides of the gear box; a set sliding bridge mechanism that synchronized the tandem prop-rotors blade pitch turning; and a driving pulley chain or bell driving system. When engine power up the driving pulley, the primary prop-rotor mounted with the pulley rotates, and drives the gear box.

Abstract: A turboprop having at least one propeller formed by a set of variable pitch blades. In the invention, each blade is swivel-mounted on a rotary support and carries a gearwheel meshing with an actuator annulus rotating on said rotary support and coupled to a control annulus via an epicyclic mechanism.

Abstract: The invention described here offers a low-cost method of remote flight control suitable for use in toy airplanes and ornithopters (flapping-wing aircraft). To accomplish this, the aircraft is powered by a reversible electric motor. The propeller or flapping wing produces a torque force, which is dependent upon the direction of motor rotation. This torque force is used to bank the aircraft and cause a turn. In the case of an airplane, a reversible-pitch propeller enables the propeller to produce thrust in either rotational direction. In the case of an ornithopter, the torque force results from an asymmetrical motion of the wings. By reversing the motor direction, the asymmetry is reversed and the ornithopter turns in the opposite direction. This control method reduces costs, because unlike other toy aircraft control systems, it provides full directional control of the aircraft without the need for any servo or actuator in addition to the drive motor.

Abstract: A radio-controlled electrically-powered model flying wing aircraft having a pusher propeller at the rear wing root powered by an electric motor mounted in a streamlined electric motor housing that extends into the wing and blends smoothly into the wing surface at the center wing chord. The motor housing, motor and propeller extend beyond the wing trailing edges to ensure efficient propeller operation and to reduce propeller-induced noise. A battery is secured in a resilient pouch and protected completely inside the wing root, serviceable from the bottom wing surface by removing a quick release flap. Major structural elements are composed of impact resistant, flexible, and resilient materials.

Abstract: Propeller-driven aircraft (30) comprising an engine (31) providing mechanical engine power for rotating a propeller (32), an engine limiting unit (35), an engine control unit (37) for controlling the mechanical engine power of the engine (31), a system (36) for measuring the airspeed and providing information concerning the airspeed to the engine limiting unit (35), wherein the engine limiting unit (35) automatically reduces the mechanical engine power at airspeeds below a certain first airspeed value (V1).

Abstract: In order to provide a compact, high-performance drive device for aircraft, in particular for power gliders, which comprise a propeller which is driven by a motor, preferably by an electric motor, and the blades (6) of which can be tilted towards the propeller shaft (15) by way of a joint and in the tilted-out position pass through a running gap (5) for the propeller formed between the nose (4) of the aircraft and the fuselage (2) by displacement of the said nose, in which the generally minimal conditions of space are utilized in an optimum manner and which ensures the necessary aerodynamic properties of the aircraft, the invention proposes that the motor (10) should be arranged in front of the propeller in the space bounded by the nose (4). In this way, the interior of the aircraft as far as the running gap (5) for the propeller is made available for the pilot or the aircraft passengers, so as to ensure optimum use of the said interior and the length of the aircraft can be kept short.

Abstract: A funnel strip is added to a rotary airfoil, which utilizes the Bernoulli principle to increase the velocity of air over the suction side of the rotating airfoil to increase the lift. The device is applicable to thrust-producing devices, such as propellers, as well as to wind-powered devices.

Abstract: An aircraft (10) having turboprop propulsion has a plurality of gas turbine engines (11), each with a two stage reduction gearbox (30,41) with the engine output shaft (17,17A) inline with the propeller drive output shaft (19,51) to drive a propeller (12) in front of the engine in a tractor mode of propulsion. The input gear reduction stage (20) and output gear reduction stage (21) share a plurality layshafts (22,38) mounted in fixed circularly-spaced relation to each other about the axis of the output shafts in the mechanical housing in the aircraft. Each layshaft of said plurality of layshafts has a layshaft first end toward the rear, input end of the gearbox, and a layshaft second end toward the output, front end of the gearbox. The layshaft gears are arranged to avoid any net thrust loading of the layshafts. Spur (26) and double helical (27) are used in FIG. 4, while spur gears 37 and 48 are used in FIG. 6 with suitable helix settings to neutralize end thrust on layshaft 38.

Abstract: The device for lift and to reduce forward resistance of aircraft consists of a converging input duct of truncated-cone-shaped or truncated-pyramid-shaped, arranged lengthwise inside the fuselage and inclined to the longitudinal axis, with the larger opening coinciding with the front fuselage contour or periphery of maximum cross-section, and reducing in bore backwards so that its generatrix or lower side coincides with the lower surface of the fuselage parallel to the aircraft's longitudinal axis and the generatrix or upper edge forms an acute angle with the aircraft's longitudinal axis. The narrowest end of the duct discharges into the input of the turbofan, UHD, etc. type drive engines which discharge through a rear outlet duct facing backwards with the rear end curved slightly downward.

Abstract: A propeller propulsion unit for aircrafts in general including a rotation shaft driven by a motor, the unit including a single-blade propeller and a counterweight that are connected to the shaft, the counterweight being arranged in a substantially diametrical position with respect to the single blade in order to balance the moment generated by centrifugal force and being variably offset with respect to the axis of the blade in order to balance the moment generated by the traction force of the single-blade propeller.

Abstract: An apparatus and method for reducing noise within the fuselage of a propeller driven aircraft. In one embodiment the propeller blades are spaced apart and in front of an offset inlet. The inlet provides air to a gas turbine engine powering the propeller, and also to a scavenge duct. The propeller blades and inlet are spaced apart such that during cruise conditions for the aircraft, the trailing edge of the propeller blades are spaced apart from the inlet by more than one-fourth of the chord length of the propeller blades, and less than about the chord length of the propeller blades. This spacing reduces the aerodynamic interaction between the propeller blades and a bubble of partially stagnated air in front of the inlet. In another embodiment, the scavenge duct is constructed such that it flows an increased amount of air, thus allowing the inlet duct to flow an increased amount of air.

Abstract: An airboat propelling system is provided wherein a propeller is rotated by a hollow driven shaft. A further embodiment is provided wherein two propellers are rotated in opposite directions by counter-rotating coaxial hollow driven shafts. Floating stiffener bearings positioned between the coaxial hollow driven shafts suppress flexion and protect the opposing surfaces of the shafts. These innovative techniques permit a minimization of size and weight, as well as a reduction in rotational speed of the propellers, maximizing efficiency and decreasing noise.

Abstract: A method and apparatus to balance propeller blades including, but not limited to, those used on model aircraft provides relocation of the propeller's center mounting hole to the propeller's center of mass by installation of appropriate eccentric bushings into the center mounting hole, and preferably into an oversize center mounting hole that has been created in the propeller hub. Both spanwise and chordwise propeller balance can be made with this eccentric bushing method.

Abstract: A propeller for fluid propulsion (such as air or water) comprises a pair of substantially rigid blades. The blades are mounted for rotation about respective, separate, parallel rotation axes, with the axes being also substantially parallel to the longest dimension of the blades. The blades each define a plate that is oppositely helically twisted along the longest blade dimension compared with the other blade. The blades are positioned together in synchronously opposite, rotatable condition, with the rotating blades passing by each other in closely spaced relation without physical contact. A tubular housing encloses the rotating blades in closely-spaced relation between the housing and blades. Such a blade system can provide a high velocity jet of large mass at relatively low rotational speed.