초록 ▼

A ducted fan type model aircraft power plant having a mounting for a one cylinder internal combustion model aircraft engine. The preferred engine utilizes a special vertically oriented carburetor. A duct is supported by a set of stators having an aerodynamic shape for straightening airflow through t

A ducted fan type model aircraft power plant having a mounting for a one cylinder internal combustion model aircraft engine. The preferred engine utilizes a special vertically oriented carburetor. A duct is supported by a set of stators having an aerodynamic shape for straightening airflow through the duct. A fan having seven identical individual replaceable blades is disposed at the front of the duct and directly driven by the engine. One stator is adapted to essentially enclose the vertical carburetor and to smoothly direct the airflow from the fan around the carburetor to the engine cylinder for cooling. The stator has an opening to the carburetor air inlet for providing air under pressure thereto. The stator shapes cooperate with the duct and aft fairings of the power plant to deliver a smooth airstream having a uniform non-turbulent flow to produce a maximum propulsive efficiency.

대표청구항 ▼

1. A power plant for model jet aircraft comprising: an approximately cylindrical duct having an internal surface; an engine mount having a forward cylindrical portion, having an external surface and an internal surface, said cylindrical portion essentially concentric with said duct and a rear en

1. A power plant for model jet aircraft comprising: an approximately cylindrical duct having an internal surface; an engine mount having a forward cylindrical portion, having an external surface and an internal surface, said cylindrical portion essentially concentric with said duct and a rear engine mounting portion; an engine having a forward projecting drive shaft and mounted on said rear portion of said engine mount having said drive shaft concentric with said forward cylindrical portion of said engine mount; a vertically oriented carburetor mounted on said engine and projecting upward through the top surface of said duct, said carburetor having controls external to said duct; primary stator means disposed forward of said carburetor for directing airflow through said duct around said carburetor and disposed between the external surface of said cylindrical portion of said mount and the internal surface of said duct for supporting said mount; a plurality of secondary stators between the external surface of said cylindrical portion of said mount and the internal surface of said duct for supporting said mount, said primary stator, said secondary stators, and said duct defining a plurality of airflow passages from the front of said duct to the rear thereof; and a multibladed fan disposed in and enclosed by the forward end of said duct, said fan mounted on said drive shaft, said fan driven by said engine to produce a generally spiralling airflow rearward through said airflow passages, said primary stator and secondary stators having an arcuate fore to aft shape for straightening said rearward airflow. 2. The power plant as defined in claim 1 in which: said external surface of said cylindrical portion of said mount includes grooves formed therein; said internal surface of said duct includes grooves formed therein; and the inner and outer edges of said stators are adapted to match said engine mount grooves and said duct grooves to thereby form a rigid assembly. 3. The power plant as defined in claim 1 in which: said engine has a vertically oriented cylinder aft of said duct. 4. The power plant as defined in claim 1 in which said airflow passages have essentially uniform cross-sectional areas whereby a set of airstreams issuing from the rear of said duct have essentially uniform transverse pressure gradients. 5. The power plant as defined in claim 1 having three of said secondary stators in which: said primary stator and said secondary stators define four of said airflow passages; said primary stator has a larger frontal area than each of said secondary stators; and said approximately cylindrical duct includes a semicylindrical lower portion thereof and an upper portion which varies from a semicylindrical shape at its forward end to a non-semicylindrical shape slightly higher at its rearward end to compensate for the larger frontal area of said primary stator. 6. The power plant as defined in claim 1 in which said cylindrical duct includes a circular shroud ring mounted thereto and surrounding said multibladed fan, said shroud ring having mounting holes for fastening to said duct by mounting screws, said holes larger in diameter than said mounting screws to permit accurate centering of said fan in said shroud ring. 7. The power plant as defined in claim 6 in which: said circular shroud ring includes a rabbetted forward edge for receiving a complementary air inlet duct to provide a smooth airflow across the joint thereby formed; and said duct includes a rabbetted rear edge for receiving a complementary airflow outlet duct to provide a smooth airflow across the joint thereby formed. 8. A power plant for model jet aircraft comprising: an essentially cylindrical duct; an engine mount having a forward cylindrical portion having an external surface and an internal surface, said cylindrical portion essentially concentric with said duct; a primary stator and a plurality of secondary stators disposed between the external surface of said cylindrical portion of said mount and the internal surface of said duct for supporting said mount, said stators also forming a plurality of airflow passages from the front of said duct to the rear thereof; an engine having a forward projecting drive shaft and mounted on the rear portion of said engine mount having said drive shaft concentric with said forward cylindrical portion of said motor mount; a multibladed fan disposed in and enclosed by the forward end of said duct, said fan mounted on said drive shaft, said fan driven by said engine to produce a generally spiralling airflow rearward through said airflow passages, said primary stator and secondary stators having an arcuate fore to aft shape for straightening said rearward airflow; said engine having a vertically oriented cylinder aft of said duct and a vertically oriented carburetor mounted on said engine and projecting upward through the top surface of said duct; said primary stator flaring outwardly from fore to aft to surround said vertically oriented carburetor for directing a uniform airflow from said fan around said engine cylinder for cooling thereof; and fairing means aft of said engine cylinder for directing said cooling airflow from said engine cylinder rearward to maintain a uniform airflow characteristic. 9. The power plant as defined in claim 8 in which: said vertically oriented carburetor includes a forwardly directed carburetor air opening; and said primary stator includes an opening in the forward surface thereof communicating with said carburetor air opening for directing pressurized air from said fan into said carburetor. 10. The power plant as defined in claim 8 in which: said engine includes a rearwardly directed exhaust tube; and said fairing means includes a portion enclosing said exhaust tube and said rear portion of said engine mount to maintain a uniform rearward airflow. 11. The power plant as defined in claim 8 in which: said primary stator includes a cutaway portion adjacent to the top internal surface of said duct; and said vertically oriented carburetor has an upper portion thereof relieved to form a narrow web; whereby airflow from said fan passes through said cutaway portion of said primary stator and around said narrow web to supply cooling air to the front of said cylinder. 12. A power plant for model jet aircraft comprising: an essentially cylindrical duct having an internal surface; an engine mount having a forward cylindrical portion, having an external surface and an internal surface, said cylindrical portion essentially concentric with said duct and a rear engine mounting portion; a primary stator and a plurality of secondary stators disposed between the external surface of said cylindrical portion of said mount and the internal surface of said duct for supporting said mount, said stators also forming a plurality of airflow passages from the front of said duct to the rear thereof; an engine having a forward projecting drive shaft and mounted on said rear portion of said engine mount having said drive shaft concentric with said forward cylindrical portion of said engine mount; a multibladed fan disposed in and enclosed by the forward end of said duct, said fan mounted on said drive shaft, said fan driven by said engine to produce a generally spiralling airflow rearward through said airflow passages, said primary stator and secondary stators having an arcuate fore to aft shape for straightening said rearward airflow; said fan having a multiplicity of identical individual blades, each blade having an arcuate base portion, said base portion including a cylindrical boss having a concentric opening therethrough, wherein said arcuate bases are adapted to be assembled to form a circular outer hub, a pair of blade mounting inner hub discs, each having a multiplicity of cylindrical studs distributed uniformly around the periphery of a face thereof, and an essentially hemispherical spinner hub wherein said multiplicity of blades is clamped between said pair of inner hub discs with said cylindrical studs inserted into said cylindrical boss openings, with said pair of inner hub discs bolted to a rear surface of said spinner hub and concentric therewith to securely clamp said blades between said pair of inner hub discs. 13. The power plant as defined in claim 12 in which said multibladed fan assembly is attached to said drive shaft by a concentric hexagonal socket head bolt, said head bolt thereby providing a connection for a hexagonal end starting bar for starting of said engine. 14. The power plant as defined in claim 12 in which said spinner hub includes a flat peripheral portion suitable for engagement by a starter belt for starting of said engine. 15. A power plant for model jet aircraft comprising: an essentially cylindrical duct having an internal surface and an external surface; an engine mount having a forward cylindrical portion having an external surface and an internal surface, said cylindrical portion essentially concentric with said duct and a rear engine mounting portion for mounting an engine, having a forward projecting drive shaft, on said rear portion of said engine mount having said drive shaft concentric with said forward cylindrical portion of said engine mount in which said engine has a vertically oriented cylinder aft of said duct and a vertically oriented carburetor, having carburetor controls, mounted on said engine forward of said cylinder, said duct having a top surface having an opening therethrough to permit said carburetor to project upward through said top surface of said duct with said carburetor controls external to said duct, said carburetor having a forwardly directed air opening; a primary stator and a plurality of secondary stators disposed between said external surface of said cylindrical portion of said mount and said internal surface of said duct for supporting said mount essentially concentric with said duct, said stators also forming a plurality of airflow passages from the front of said duct to the rear thereof, each of said passages defining a volume through which air may flow, said primary stator having a forward surface and flaring outwardly from said forward surface fore to aft around said vertically oriented carburetor; and a multibladed fan disposed in and enclosed by the forward end of said duct, said fan to be mounted on the drive shaft of said engine and to be driven thereby to produce a generally spiralliy airflow rearward through said airflow passages, said primary stator and secondary stators having an arcuate fore to aft shape for straightening said rearward airflow, and said flared primary stator directing a uniform airflow around said engine cylinder for cooling thereof and said primary stator having an opening through said forward surface for communicating with said carburetor air opening for directing pressurized air from said fan into such carburetor, said airflow passages formed by said primary stator and secondary stators are arranged to equalize said volumes of said passages to produce a set of airstreams issuing from the rear of said duct having essentially uniform cross-sectional areas and essentially equal transverse pressure gradients. 16. The power plant as defined in claim 15 in which said cylindrical duct includes a circular shroud ring surrounding said multibladed fan, said shroud ring adjustably mounted to said duct to permit accurate centering of said fan in said shroud ring. 17. The power plant as defined in claim 16 in which said multibladed fan includes a multiplicity of identical individual blades, each blade having an arcuate base portion, said base portions adapted to be assembled to form a circular outer hub. 18. The power plant as defined in claim 15 in which said primary stator and said secondary stators have a cross-sectional airfoil shape with sharp leading edges thereof.