Helicopter With Coaxial Counter-Rotating Dual Rotors and No Tail Rotor

This invention relates to the field of aircraft, especially helicopters.

Helicopters have been known for more than sixty years but have only in the last twenty-five years become of any real value in military usage, police assistance, and rescue activities. It was quickly learned that the actions of and reactions to the forces of an overhead rotating rotor caused the body of the helicopter to rotate about the shaft driving the rotor and this problem was solved by mounting a vertical rotor at the distal end of the tail to produce a force to counteract the spinning of the body.

Many attempts have been made to employ dual rotors but none has been successful commercially without the assistance of a tail rotor to stabilize the machine and to prevent spinning of the body.

It is an object of this invention to provide a helicopter with a dual coaxial rotor system with counter-rotating rotors and no tail rotor. It is another object of the invention to provide a helicopter with no tail rotor but with rear airfoils for directional control. Still other objects will become apparent from the more detailed description which follows.

This invention relates to a helicopter having two counter-rotating horizontal rotors spaced apart vertically above the helicopter body and having a tail boom extending aft of the helicopter body to support at its distal end two pairs of air foils pivotable respectively about a horizontal axis and a vertical axis to provide directional control of the helicopter. No tail rotor is employed on this helicopter.

In specific and preferred embodiments of the invention the two rotors are fixed as to the angle of the leading edge, and operate at identical rotational speeds. The rotors are rotated by a single vertical shaft and a gear transmission that includes a planetary gear system.

The tail fin assembly includes a pair of larger vertical air foils adapted to be pivoted about horizontal axes; and a pair of smaller vertical air foils adapted to be pivoted about vertical axes.

The novel features believed to be characteristic of this invention are et forth with particularity in the appended claims. The invention itself, however, both as to its organization and method of operation, together with further objects and advantages thereof, may best be understood by reference to the following description taken in connection with the accompanying drawings in which:

FIG. 1 is a perspective schematic view of the helicopter of this invention;

FIG. 2 is a cross-sectional view of the gear transmission at 2--2 of FIG. 3;

FIG. 3 is a vertical cross-section through the propellers and gear transmission of the invention;

FIG. 4 is a top plan view of the air foil assembly on the tail boom of the helicopter;

FIG. 5 is a rear elevational view of the air foil assembly on the tail boom of the helicopter;

FIG. 6 is rear elevational view of the air foil assembly on the tail boom in straight vertical or horizontal flight;

FIG. 7 is a rear elevational view of the air foil assembly on the tail boom in a left turn; and

FIG. 8 is rear elevational view of the air foil assembly on the tail boom in a right turn.

The various features of this invention are best understood by reference to the attached drawing.

In FIG. 1 there is a perspective view of what the helicopter looks like in flight. The helicopter 10 is an open structure of steel tubing holding the necessary components together in a rigid arrangement. A pilot 11 sits in a seat 12 and rests his feet on a floor board 15 which supports control pedals for operation by the pilot's feet A control stick 14 projects upwardly between the pilot's legs and is conveniently reached by the pilot's hands. The helicopter may have skids (as shown here) or wheels, or other ground contact. A tail boom 22 extends to the rear of the helicopter and supports a pair of large air foils 23 which pivot about horizontal axes generally parallel to the tail boom 22; and a pair of small air foils 24 which pivot about vertical axes generally perpendicular to the horizontal axes.

The two rotors 17 and 18 rotate in opposite directions as shown by arrows 20 and 21 and are driven from a common vertical shaft 16, which in turn is driven by motor means 13. Preferably, there are two separate internal combustion engines, supplied by gasoline via tanks 13', both engines being connected to shaft 16 by clutches which can be separately operated to connect either engines to shaft 16. Rotors 17 and 18 are preferably substantially the same length (about 10-18 feet) and same size and shape. The two rotors have an identical unchangeable or fixed pitch. There is a CV joint 76 to provide an upper tiltable portion to main shaft 16. Transmission 19 is mounted on tiltable portion 78, as are rotors 17 and 18. Tiltable portion 78 is necessary to tilt rotors so as to direct the movement of the helicopter in its flight.

Arms 75 connect tiltable portion 78 to hydraulic cylinders 74 for the force to tilt rotors 17 and 18 to the desired position.

In FIG. 2 there is shown the arrangement of gears in transmission 19. An external lousing 25 encloses the transmission gears. An internal housing 26 supports some of these gears. External housing 25 is rigidly connected to lower rotor 18 and turns with the rotation of that rotor. Internal housing 26 is stationary and external housing 25 rotates opposite to shaft 36 as will be seen from the following description of the gear trains in the transmission.

Around the inside wall of external housing 25 is mounted a circumferential gear rack 27. A plurality, preferably four, compound planetary gears 29 are meshed with gear rack 27. "Compound gears" in this patent application means two gears mounted coaxially on a single spindle such that both gears turn in the same direction at the same speed. Compound gears 29 in this invention comprise a lower larger gear 31 and an upper smaller gear 30 mounted on a spindle 32. Larger gears 31 are meshed with gear rack 27. Shaft 16 (in tiltable portion 78) is positioned in the center of external housing 25 and internal housing 26 extending perpendicularly upward and downward from the plane of the drawing of FIG. 2. Large driving gear 28 is rigidly attached to shaft 16, turning with the rotation of shaft 16. Drive gear 28 is meshed with the smaller upper gears 30 of compound gears 29. It may be seen by tracing he directions of movement of gears 28, 29, 30 and 32 from either selected direction of rotation of shaft 16, that shaft 16 and external housing 25 always rotate in opposite directions. Thus, when upper propeller 17 is fastened to shaft 16 and lower rotor 18 is fastened to external housing 25 the two propellers will rotate in opposite directions and will be coaxial since both are centered on shaft 16. By appropriate choice of the number of gear teeth an the size of gears 28, 30, 31 and of gear rack 27, the rotational steed of the two propellers 17 and 18 can be made the same, as is the preferred operation of this invention. It should be noted that internal housing 26 must have some gaps 33 in its side walls to permit lower large gears 31 to be spindled in internal housing 26 and also to be meshed with gear rack 27. External housing 25 is a tightly sealed enclosure around internal housing 26 and all of the gears and thereby is generally filled with oil so as to lubricate all internal moving gears, spindles, bearings, etc.

In FIG. 3 there is shown a vertical cross section through the transmission 19 and all other components between the two propellers 17 and 18. The central power component is shaft 16 which is machined with step ledges to accept bearings, gears, or other parts. There are five step ledges where the diameter of shaft 16 changes to provide a ledge for mounting components onto shaft 16. Beginning at the top of shaft 16 in FIG. 3 and moving downward there is step ledge 40 to provide a seat for mounting upper propeller 17 and fasten it rigidly to shaft 16 so as to rotate with shaft 16. A washer 64 and nut 63 are shown to engage screw threads 79 so as to clamp propeller 17 to shaft 16. A second step is at 42 to provide a ledge with screw threads 52 to receive clamp nut 53 to force the top plate 59 of internal housing 26 and upper thrust bearing 49 against third step ledge 44. Fourth step ledge 45 provides a seat for large driving gear 28 to be mounted rigidly on shaft 16 to rotate with shaft 16. A fifth step ledge 37 is the lowest of the step ledges and it provides a seat for lower thrust bearing 49 in an appropriate supporting beam 34 of the framework of the body of helicopter 10. The main bearing surface of shaft 16 is between step ledges 37 and 44. For substantially all of this length shaft 16 is enclosed in a support sleeve 46 which is immovable and is rigidly bolted or otherwise fastened to the body of helicopter 10.

Sleeve 46 supports lower propeller 18, external housing 25, and spacer support 56, all of which rotate with propeller 18. Bearings 51 in seats on the outer surface of sleeve 46 permit propeller 18 and its attachments to rotate around sleeve 46, while shaft 16 rotates within sleeve 46. The upper end of sleeve 46 is threaded on its outside surface at 47. Upper clamp nut 53 is threaded onto threaded portion 47 and bears against internal housing 26 to clamp the housing 26 tightly against lower clamp nut 53 which provides a lower seat for housing 26 and positions its gears accurately. Lower clamp nut 53 bears against washer 55 and bearing 51. The entire inner hollows of external housing 25 and support spacer 56 are filled with oil to provide lubrication of all interior parts. Oil seals 50 and 80 provide appropriate sealing to prevent oil leakage.

At the upper portion of external housing 25 there is a hub structure of block 62, cover 62, bearing 51, and oil seal 50 around shaft 16. This structure may take on various shapes and or sizes. It merely closes the top of external housing 25 while providing an access way into the interior, and also provides a seat for bearing 51.

The remaining FIGS. 4-8 show the structure and operation of the rudder means which direct the helicopter in its flight. The structure consists of a tail boom 22 extending from the aft portion of the helicopter body to support two pairs of air foils 23 and 24. Air foils 23 are intended to react to the downward flow of air from rotors 17 and 18. The air directed against air foils 23 will cause the tail boom 22 to swing right or left, and thus pointing the nose of the helicopter in the direction desired by the pilot. Air foils 24 function similarly to the tail of an airplane in that air flowing along the length of the airplane is directed against the tail surface to swing the tail right or left. Thus the combination of forces on air foils 23 and 24 direct the helicopter of this invention as the pilot wishes. The pilot, of course, operates controls to move air foils 23 and/or 24 as desired.

The general structure of this tail assembly includes a horizontal rod 71 which supports an L-shaped pivot shaft 65 at each end of rod 71. Each shaft 65 supports one air foil 23 and one air foil 24 such that the result is a pair of widely spaced air foils 23 and a pair of widely spaced air foils 24 are available to control the direction of flight. Suitable tie rods 68 and 69 connect air foils 23 and 24 to a central control lever 70. The tie rods 68 and 69 assure that both air foils 23 move identically at the same time; and both air foils 24 move identically and at the same time. Control lever 70 is moved by the pilot as he steers the helicopter. The control means includes a single hydraulic cylinder 72 at the distal end 73 of tail boom 22 to simultaneously move all air foils.

The movement of air foils 23 and 24 is shown in FIGS. 4 and 5 in dotted lines where 23R and 24R represent the extreme right hand limit of movement; and 23L and 24L show the extreme left hand limit of movement of each air foil. In FIG. 6 the position of air foils 23 and 24 is shown for upward, downward, and straight forward flight of the helicopter. In FIG. 7 the positions of air foils 23 and 24 are shown (looking from behind the helicopter) which will cause the tail to swing to the right, producing a turn to the left. In FIG. 8 the positions of the air foils 23 and 24 will cause the tail to swing to the left, producing a turn to the right. These effects of forcing the tail right or left are sometimes referred to as a yaw to the right or left.

The structure of pivot shafts 65 includes a long horizontal leg 67 and a short vertical leg 66. A more precise description of horizontal leg 67 is that it is parallel to the axis of tail boom 22. Similarly a more, precise description of vertical leg 66 is that it is perpendicular to horizontal leg 67 and lies in a plane that is parallel to the axis of tail boom 22 and includes horizontal leg 67. It is realized that the terms "horizontal" and "vertical" must take into account the earth; and that the helicopter is in different positions when flying. Nevertheless, horizontal and vertical are used here to generally represent the condition when the helicopter is resting upright on the ground.

While the invention has been described with respect to certain specific embodiments, it will be appreciated that many modifications and changes may be made by those skilled in the art without departing from the spirit of the invention. It is intended, therefore, by the appended claims to cover all such modifications and changes as fall within the true spirit and scope of the invention.