Abstract:
The invention is an aircraft that includes a flying wing having a plurality of extendable flaps mounted on the trailing edge of the flying wing. A canard is mounted on the nose of said flying wing. A system is mounted in the flying wing for providing high pressure air over the canard and the flaps. A second system is provided for controlling the flow of air over the canard to provide pitch control of the aircraft.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to the field of flying wing aircraft and, in particular, to a flying wing aircraft with lift augmentation systems. 
     2. Description of Related Art 
     Flying wing type aircraft are old in the art. They are generally characterized as having an integrated central portion (fuselage in conventional aircraft) and wings wherein both produce lift. The aerodynamic efficiency of flying wing aircraft is well established. 
     Canards are also old in the art, and some designs, such as the Russian TU-144 supersonic transport, have retractable and are only used for takeoff and landing. Also blown flaps, are old in the art. Such systems are known to greatly improve the lift of the wings. In U.S. Pat. Nos. 3,056,566 Jet Propelled Aircraft by I. M. Davidson and 5,992,792 Aircraft With Jet Flap Propulsion by K Arnason, et al. disclose aircraft with blown canards incorporating a rear mounted blown flap. Such systems are called by various names (e.g. jet flaps, blown flaps, etc.) however they simply exercise circulation control of the surrounding air to achieve lift augmentation. 
     However, none of the prior art disclose a flying wing type aircraft with a blown retractable canard, without flaps, and blown main wing flaps, wherein the pitch of the aircraft at low speed is controlled by varying the flow of air over the canard. 
     Thus, it is a primary object of the invention to provide a flying wing type aircraft with a retractable canard. 
     It is another primary object of the invention to provide a flying wing type aircraft with a retractable, circulation control canard. 
     It is a further object of the invention to provide a flying wing type aircraft with a retractable, circulation control wherein the airflow over the canard can be varied to provide pitch control. 
     SUMMARY OF THE INVENTION 
     The invention is an aircraft that includes a flying wing having a longitudinal axis, vertical axis, and a horizontal axis. The leading edge of the wing from the nose has a sweep angle of 30 to 80 degrees from the horizontal axis and may have an outboard segment with the leading edge sweep angle similarly defined of between 0 and 80 degrees as measured from a local horizontal. 
     A canard is mounted near the nose. The aircraft&#39;s canard, being generally only needed when taking off and landing is retractable. The aircraft also includes a plurality of extendable flaps mounted on the trailing edge of the flying wing. Various means for providing circulation control of the wing and the canard may be employed. In this description an air distribution system is mounted in the flying wing for providing high pressure air over the canard and the flaps as a means to increase control power and aircraft lift. The air distribution, preferably, includes a propulsion system for powering the aircraft comprises at least one turbofan engine, the propulsion system adapted to provide fan air for takeoff or fan air in combination with compressor bleed air upon landing. A ducting system is coupled to the at least one turbofan engine and is connected to a first air distribution system for directing air flow over the flaps and a second air distribution system for directing air over the canard. An air flow system is provided for controlling airflow over the canard to provide pitch control to the aircraft. 
     The novel features which are believed to be characteristic of the invention, both as to its organization and method of operation, together with further objects and advantages thereof, will be better understood from the following description in connection with the accompanying drawings in which the presently preferred embodiment of the invention is illustrated by way of example. It is to be expressly understood, however, that the drawings are for purposes of illustration and description only and are not intended as a definition of the limits of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a planform view of a flying wing type aircraft partially broken away to show the interior thereof. 
         FIG. 2  is a partial cross-sectional view of  FIG. 1  illustrating the canard actuation system. 
         FIG. 3  is a front view of the aircraft shown in  FIG. 1 . 
         FIG. 4  is a view of the aircraft shown in  FIG. 1  partially broken away to show the engines. 
         FIG. 5  is a schematic view of the system for blowing air over the flaps and canard of the aircraft shown in  FIG. 1 . 
         FIG. 6  is a cross-sectional view the canard taken along the line  5 - 5  in  FIG. 1  illustrating the airflow about the canard when the canard is blown. 
         FIG. 7  is a cross-sectional view of one of the flaps at the trailing edge of the wing. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to  FIGS. 1-5 , the flying wing aircraft, is generally designated by numeral  10  and has longitudinal axis  11 A, vertical axis  11 B and a horizontal axis  11 C. The aircraft  10  includes a nose end  12 , tail end  13  with an overall length  15 . The right and left inner leading edges  16 A and  16 B extend back from the nose end  12  over a distance  17  at a sweep angle  18 , of between 30 and 80 degrees. The distance  17  is about 40 to 60 percent of the total length  15  of the aircraft. The left and right outer leading edges  16 C and  16 D A have a sweep angle  22 , of between 0 and 80 degrees as measured from a local horizontal. 
     Mounted in proximity to the left and right inner leading edges  16 A and  16 B are right and left canards  24 A and  24 B having Coanda effect airfoil cross-sections (see  FIG. 5 ). The canards  24 A and  24 B have an axis of rotation  25 A and  25 B, respectively and an actuation system  26  that retract the canards to form part of the leading edge  16 A and  16 B or the canards may be retracted onto the wing surface. The actuation system  26  will be subsequently discussed. The canards  24 A and  24 B have a downward angle  28 A or upward angle  28 B of between 0 and 20 degrees (see  FIG. 3 ). 
     The left and right inner trailing edges  30 A and  30 B include inboard trailing edge flaps  32 A and  32 B, while the outer left and right outer trailing edges  34 A and  348  include outboard trailing edge flaps  36 A and  36 B. External of the outboard flaps  36 A and  36 B are split rudders  38 A and  38 B. Referring particularly to  FIG. 5 , the outer left flap  36 A has a pivot axis  39  and actuator(s)  40 . All the flaps are similar. 
     Again referring to  FIGS. 1-7 , the left and right inner trailing edges  30 A and  30 B extends forward from the tail end  13  over a distance  42 , which is between 15 and 40 percent of the length  15 , at a forward sweep angle  44  of between 0 and 45. The left and right outer trailing edge portions  34 A and  34 B are generally parallel to the left and right outer leading edges  30 A and  30 B, respectively. 
     Mounted within the flying wing are four turbofan engines  46 A,  46 B  46 C and  46 D. However, while four engines are shown, the aircraft could only have other propulsion systems and corresponding quantities. The four engines  46 A- 46 D have inlet ducts  48  and exhaust ducts  49  all on the top surface of the aircraft. The engines  46 A- 46 B have compressor sections  50 A,  50 B,  50 C and  50 D and fan sections  51 A,  51 B,  51 C and  51 D. 
     A pressurized air distribution system, indicated by numeral  52 , is installed in the aircraft  10 . The distribution system  52  is divided into two halves  52 A and  52 B. Distribution system  52 A includes lines  53 A and  53 B coupled to the fan sections  50 A and  50 B of the engines  46 A and  46 B which included pressure regulator shut off valves  54 A and  54 B mounted therein. The lines  53 A and  538  connect to a distribution duct  55 , which provides high pressure air to ducts  56 A and  56 B and  56 C. 
     At takeoff, the engines are at full power and there is sufficient air at high enough pressure level that only fan air is necessary. However, upon landing, where the engines are at a reduced power setting, additional air from the compressor sections of the engine is provided to maintain pressure levels. Thus coupled to the distribution duct  55  are lines  59 A and  59 B, having control pressure regulator valves  60 A and  608  mounted therein, which are connected to the compressor section  51 A and  51 A of the engines  46 A and  46 B. Therefore, upon landing, the valves  60 A and  60 B are opened. 
     Duct  56 A connects to distribution channel  61 A, which distributes air over the left outboard flap  36 A and part of inboard flap  32 A via slot  57  (see  FIG. 6 ). Duct  56 B connects to distribution channel  61 B, which distributes air over the left inboard flap  32 A. Duct  56 C distributes air to distribution channel  61 C via a flow control valve  62  and pivoting connection  64  to left canard  24 A (see  FIG. 5 ) The valve  62  is used to control the airflow over left canard  24 A, which exits slot  63  in the distribution channel  61 C to very the lift produced thereby (see  FIG. 6 ). 
     The distribution system  50 B includes lines  72 A and  72 B coupled to the fan sections  51 C and  51 D of the engines  46 C and  46 D which include pressure regulator shut off valves  73 A and  73 B mounted therein. The lines  72 A and  72 B connect to a distribution duct  74 , which provides high pressure air to ducts  76 A and  76 B and  76 C. 
     As previously stated, at takeoff, the engines are at full power and there is sufficient air at high enough pressure level that only fan air is necessary. However, upon landing, where the engines are at a much reduced power setting, it is necessary to provide additional air from the compressor sections of the engine to maintain pressure levels. Thus coupled to the distribution duct  74  are lines  79 A and  79 B, having control pressure regulator valves  80 A and  80 B mounted therein, which are connected to the compressor section  50 C and  50 D of the engines  46 C and  46 D. Therefore, upon landing, the valves  80 A and  808  are opened. 
     Duct  76 A connects to distribution channel  81 A, which distributes air over the trailing edge outboard flap  36 B and part of flap  32 B. Duct  76 B connects to distribution channel  81 B, which distributes air over the left inboard flap  32 B. Duct  76 C distributes air to distribution channel  81 C via a flow control valve  82  and pivoting connection  84  to right canard  24 B. The valve  82  is used to control the airflow over right canard  24 B to very the lift produced thereby. 
     Thus at takeoff, the right and left canards  24 A and  24 B are extended. With all engines  46 A- 46 D at full power, compressor bleed air is not required and valves  60 A,  60 B and  80 A,  80 B are closed since the engines are at full power. Valves  54 A,  54 B and  73 A and  73 B are open. Valves  62  and  82  are open and modulating airflow to the canards  24 A and  24 B. After takeoff, the left and right canards  24 A and  24 B are no longer required and are retracted and valves  54 A,  54 B and  73 A,  73 B are closed. Upon approach to and landing, the left and right canards  24 A and  24 B are again extended. Because the power produced by the engines  46 A- 46 D is greatly reduced, the valves,  53 A,  53 B and  73 A and  73 B are again opened as well as valves  60 A,  60 B and  80 A,  80 B, because both fan and compressor air flow is needed. A crossover duct  86  having flow control valve  87  therein connects duct  56 C to duct  76 C and is opened should an engine failure occur. 
     It should be noted that airflow for the flaps and canard can be provided by an auxiliary power unit coupled to an air pump or an electric motor driving an air pump could also be used. However, air extracted from the propulsion system is presently preferred. 
     Referring back to  FIG. 2 , the canard actuation system  26  includes two ball screw actuators  90  and  92  each having motors  94  and  96  pivotally attached to aircraft structure  98 . Each actuator  90  and  92  have screw shafts  100  and  102 , which engage nut members  106  and  108  rotatably mounted on the canards  24 A and  24 B. Thus rotation of the screw shafts  100  and  102  will cause the canards to extend or retract. For purposes of illustration the canard  24 A is shown extended and the canard  24 B are always extended and retracted in unison. It should also be noted that other actuation systems may be used. 
     While the invention has been described with reference to a particular embodiment, it should be understood that the embodiment is merely illustrative as there are numerous variations and modifications which may be made by those skilled in the art. Thus, the invention is to be construed as being limited only by the spirit and scope of the appended claims. 
     INDUSTRIAL APPLICABILITY 
     The invention has applicability to the aircraft manufacturing industries.