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Single-blade Propeller
A single-blade propeller may be used on aircraft to generate thrust. Normally propellers are multi-blades but the simplicity of a single-blade propeller fits well on motorized gliders, because it permits the design of a smaller aperture of the glider fuselage for retraction of the power plant. The counterbalanced teetering mono-blade propeller generates fewer vibrations than conventional multi-blade configurations. Often, single blade propeller configurations are touted as having a much greater efficiency than multi-blade propellers, but this is a falsehood outside the inertial losses in spinning a heavier propeller, and the minimal additional drag from added blades. Single bladed propellers are principally used to fulfill engineering requirements that fall outside the scope of efficiency. Patents US Patent 2742095 Mechanism for balancing single blade aircraft rotorUS Patent 6619585 Helicopter single-blade rotorUS Patent 5971322- Propeller propulsion unit for aircraft in gene ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Thrust
Thrust is a reaction force described quantitatively by Newton's third law. When a system expels or accelerates mass in one direction, the accelerated mass will cause a force of equal magnitude but opposite direction to be applied to that system. The force applied on a surface in a direction perpendicular or normal to the surface is also called thrust. Force, and thus thrust, is measured using the International System of Units (SI) in newtons (symbol: N), and represents the amount needed to accelerate 1 kilogram of mass at the rate of 1 meter per second per second. In mechanical engineering, force orthogonal to the main load (such as in parallel helical gears) is referred to as static thrust. Examples A fixed-wing aircraft propulsion system generates forward thrust when air is pushed in the direction opposite to flight. This can be done by different means such as the spinning blades of a propeller, the propelling jet of a jet engine, or by ejecting hot gases f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Propeller (aircraft)
In aeronautics, an aircraft propeller, also called an airscrew,Beaumont, R.A.; ''Aeronautical Engineering'', Odhams, 1942, Chapter 13, "Airscrews". converts rotary motion from an engine or other power source into a swirling slipstream which pushes the propeller forwards or backwards. It comprises a rotating power-driven hub, to which are attached several radial airfoil-section blades such that the whole assembly rotates about a longitudinal axis. The blade pitch may be fixed, manually variable to a few set positions, or of the automatically variable "constant-speed" type. The propeller attaches to the power source's driveshaft either directly or through reduction gearing. Propellers can be made from wood, metal or composite materials. Propellers are most suitable for use at subsonic airspeeds generally below about , although supersonic speeds were achieved in the McDonnell XF-88B experimental propeller-equipped aircraft. Supersonic tip-speeds are used in some aircraft like the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Motor Glider
A motor glider is a fixed-wing aircraft that can be flown with or without engine power. The FAI Gliding Commission Sporting Code definition is: a fixed-wing aerodyne equipped with a means of propulsion (MoP), capable of sustained soaring flight without thrust from the means of propulsion. History In 1935, an occasional or auxiliary motor that could be retracted was suggested by Sir John Carden. This was incorporated into the Carden-Baynes Auxiliary that first flew on 8 August of the same year. A later version of the Budig glider was powered. Categories Most motor gliders are equipped with a propeller, which may be fixed, feathered (e.g. AMS-Flight Carat), or retractable. However jet engine-powered motorgliders are now available from some manufacturers, some of which are intended for use only as "sustainer" engines, i.e. for sustaining gliding flight rather than as self-launching aircraft. Sustainer motor gliders Sustainer motor gliders must be launched like an unpowere ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Teeter-totter
A seesaw (also sometimes known as a teeter-totter in North America) is a long, narrow board supported by a single pivot point, most commonly located at the midpoint between both ends; as one end goes up, the other goes down. These are most commonly found at parks and school playgrounds. Mechanics Mechanically, a seesaw is a lever which consists of a beam and fulcrum with the effort and load on either side. Varieties The most common playground design of seesaw features a board balanced in the center. A person sits on each end, and they take turns pushing their feet against the ground to lift their side into the air. Playground seesaws usually have handles for the riders to grip as they sit facing each other. One problem with the seesaw's design is that if a child allows himself/herself to hit the ground suddenly after jumping, or exits the seesaw at the bottom, the other child may fall and be injured. For this reason, seesaws are often mounted above a soft surface such as foa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Samara (fruit)
A samara (, ) is a winged achene, a type of fruit in which a flattened wing of fibrous, papery tissue develops from the ovary wall. A samara is a Simple fruit, simple dry fruits, dry fruit, and is Dehiscence (botany), indehiscent (not Dehiscence (botany), opening along a seam). The shape of a samara enables the wind to carry the seed further away from the tree than regular seeds would go, and is thus a form of anemochory. In some cases the seed is in the centre of the wing, as in the elms (genus ''Ulmus''), the hoptree (''Ptelea trifoliata''), and the bushwillows (genus ''Combretum''). In other cases the seed is on one side, with the wing extending to the other side, making the seed autorotation (helicopter), autorotate as it falls, as in the maples (genus ''Acer (plant), Acer'') and ash trees (genus ''Fraxinus''). There are also single-wing samara such as mahogany (genus Swietenia) which have a shape that enables fluttering. Some species that normally produce paired samaras, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
