FORM 2
THE PATENTS ACT 1970
(39 of 1970)
&
The Patent Rules, 2003
Complete Specification
(See section 10 and rule 13)
An Unmanned Aerial Vehicle
Bharat Forge Limited
An Indian company registered under the Indian Companies Act, 1956.
Mundhwa, Pune Cantonment, Pune - 411036, Maharashtra, India
The following specification particularly describes the invention and the manner in which it is to be performed.

Field Of The Invention:
This invention relates to unmanned aerial vehicles (UAV), particularly fixed wing UAV’s. More particularly, this invention relates to the fixed wing UAV’s which can take off on a short distance runway.
Background Of The Invention:
An unmanned aerial vehicle (UAV) or un-crewed aerial vehicle is commonly known
as a drone. It is an aircraft without a human pilot on board.
The complete system of UAV is called Unmanned Aircraft System (UAS). A UAS consists of 3 components namely, a UAV, a ground-based controller and a system of communications between the two. The UAV’s may operate with varying degree of autonomy during flight e.g. through remote control by a human operator or autonomously with the help of onboard computers. There are many types of UAVs such as fixed wing UAV, multi-rotor UAV, fixed wing hybrid vertical takeoff and landing (VTOL) UAV.
UAVs are increasingly finding newer use in today’s world. UAVs find application in transport, agriculture, surveying, photography etc. In one typical application, a UAV may be used as a platform for high or low altitude surveys, with a payload like camera system, which may serve various purposes like mapping of landslide affected

areas, 3-dimensional terrain model construction etc. Such applications require longer fly times so as to cover larger areas in one flight.
The type of UAV to be used depends on the application for which they are being chosen. When the application is such that longer fly times are required (called endurance), there is a need of Medium Altitude Long Endurance (MALE) UAVs.
Multi-rotors can be used for such operations, however they cannot cover large distances and also, cannot achieve required height/ altitude. So the survey and mapping procedure with multi-rotors is maladroit and time consuming.
Fixed wing hybrid vertical takeoff and landing (VTOL) UAVs may also be used for such surveys. But, VTOL requires additional motor, batteries, connectors and propellers which leads to increase in its weight which further leads to increase in drag. This results in high power consumption. Drag inducing structures can reduce the lift as well as speed, which leads to reduction in endurance. Also, the noise signature of this UAV is increased substantially.
The most suitable UAV for long endurance activities like aerial imaging surveys is a fixed wing UAV. A typical fixed-wing UAV has components that include a fuselage, wings, a boom, a boom connector, a tail, landing gear, a BLDC motor, propellers etc.

All these structural components are manufactured using composite materials. A fixed-wing UAV has many advantages such as high mobility, fast speed, higher endurance and safety. But, these UAVs require long runways for takeoff and landing which becomes a problem particularly in difficult-to-access areas. There are very few places where one can get uniform surfaces which can be used as runways, especially of long length, for these UAVs.
Thus, there exists a room for advancement over the existing technology which can overcome above stated drawbacks and make the fixed wing UAVs workable in difficult-to-access areas, such as hilly terrains, where uniform surfaces or long runways are unavailable.
Objects of Invention:
Some of the objects of the present invention, which at least one embodiment herein
satisfies, are now disclosed.
One object of the invention is to provide a fixed wing UAV for long endurance activities that require long fly times.
Another object of the invention is to provide a fixed wing UAV that is capable of taking-off and landing over short distances.

Yet another object of the invention is to provide a fixed wing UAV that can work in difficult or hilly terrains.
Summary Of Invention:
Present invention provides a fixed wing UAV (1) comprising an aerodynamically shaped fuselage (2); pair of wings (12, 12 A) each consisting of a flaperon (5), at least two wing connectors (18) and at least one boom connector (11); a tail (10) consisting of rudders (8) and elevators (9) as control surfaces and at least two boom connectors (11); propeller (7) with motor (26); landing gears (3, 25) with wheels (4); propulsion systems (not shown); connecting means (14, 18,) for connecting wings (12, 12A) to fuselage (2) and booms (6) for connecting tail (10) to wings (12, 12A). The key characterizing features of the UAV of the invention are i) both first detachable wing (12) and second detachable wing (12 A) have S1223 airfoil shape (13) with a taper and are each equipped with a flaperon (5) as control surface and ii) an aerodynamically shaped fuselage (2) having a curved nose portion (15), a central portion (16), and an end portion (17) and these portions are connected through smooth curvature for aerodynamic effect. The fixed wing UAV (1) of the invention is capable of flying for long endurance activities that require long fly times and is capable of taking-off and landing over short distances in difficult terrains where no runway or short runway is available. Particularly speaking, the present invention is

focused on providing a fixed wing UAV (1) which has a capability to take off and land in short take off distance of less than 10 meter and have endurance of at least 1 hour.
List of Figures:
Figure 1 shows the fixed wing UAV of the invention
Figure 2 shows the top view of the first detachable wing of the fixed wing UAV of
the invention
Figure 3 shows the perspective view of the second detachable wing of the fixed wing
UAV of the invention
Figure 4 shows front view of the aerodynamically shaped fuselage of the fixed wing
UAV of the invention
Figure 5 shows perspective view of the aerodynamically shaped fuselage of the fixed
wing UAV of the invention
Figure 6 shows exploded view of the fixed wing UAV of the invention
Figure 7 shows the Graph for induced drag parameter vs taper ratio.
List of Parts
1 – Fixed wing UAV 4 – Wheels
2 – Fuselage 5 – Flaperon
3 – Front Landing Gear 6 – Boom

4 – Propeller 24 – F uselage holes for inserting wing
5 – Rudders connectors
6 – Elevators 25 – Rear landing gear

10 – Tail 26 – Motor of propeller
11 – Boom connector 25 27 – Insert pin arrangement for tail
12 – First Detachable Wing and wing

12 A – Second Detachable Wing 28 – First Vertical component of tail
13 – Airfoil shape 28 A – Second Vertical component of
14 – Insert Pin Arrangement for wing tail
and fuselage 30 29 – Horizontal component of tail
15 – Curved nose portion of fuselage 30 – Hinge line of flaperon on wing
16 – Central portion of fuselage 31 – Hinge line of rudder on tail’s
17 – End portion of fuselage vertical component
18 – Wing connectors 32 – Hinge line of elevator on tail’s
19 – Root Chord 35 horizontal component
20 – Tip Chord 33 – Full cut on wing
21 – MAC (Mean Aerodynamic 34 – Full cut on tail’s vertical Chord) component
22 – Length of fuselage 35 – Full cut on tail’s horizontal
23 – Height of fuselage 40 component

Detailed Description Of The Invention:
For applications which require longer flight times or higher endurance, i.e. flight times greater than one hour, fixed wing UAVs are the most suitable option. A typical fixed wing UAV has multiple components. The major components are a fuselage, landing gears, wheels, flaps, control surfaces, propeller, wings, tail, propulsion systems, connecting means etc.
Control surfaces are devices on UAV which allows to control and adjust UAV’s flight altitude. Some of the major control surfaces include ailerons, elevator and rudders.
Ailerons are the control surfaces situated on both the wings to control rolling movement of the UAV. They always work in opposite direction to each other to give the maximum roll movement when required. Elevators and rudders are also used as control surfaces in the UAV. Elevator is situated in the horizontal component of the tail of the UAV which provides pitch control to change the altitude of the UAV whenever required. Rudders control the yaw movement of the UAV.
However, one of the drawbacks of the fixed wing UAV is that it requires a long runway of more than 15 meters for taking off. For higher endurance application in difficult terrains where long runways or flat areas are not available, use of fixed wing

UAVs becomes challenging.
Accordingly, present invention provides a fixed wing UAV (1), as shown in Figure 1, said UAV (1) comprises an aerodynamically shaped fuselage (2); pair of wings (12, 12 A) each consisting of flaperon (5) as control surface, at least two wing connector (18) and at least one boom connector (11); a tail (10) consisting of rudders (8) and elevators (9) as control surfaces and at least two boom connector (11); propeller (7) with motor (26); landing gears (3, 25) with wheels (4); propulsion systems (not shown); connecting means (14, 18) for connecting wings (12, 12A) to fuselage (2) and booms (6) for connecting tail (10) to wings (12, 12A).
The main objective of present invention is to provide a fixed wing UAV (1) which can fly for long endurance activities that require long fly times and is capable of taking-off and landing over short distances in difficult terrains where no runway or short runway is available. Particularly speaking, the present invention is focused on providing a fixed wing UAV (1) which has a capability to take off and land in short take off distance of less than 10 meter and have endurance of at least 1 hour. Hence it is important to find out various factors that are affecting the takeoff, flight and landing of a fixed wing UAV (1).
There are various factors present which affect these parameters but only two are

significant contributors as given below:
1. Lift: The lift is the vertical force generated on the wings which helps UAV in becoming air borne. The lift generated on the wings principally depends on the shape of the wing airfoil section and the velocity of the UAV. The lift coefficient is a dimensionless coefficient that relates to the lift generated by a lifting body to the fluid density around the body, the fluid velocity and an associated reference area. A lifting body is a foil or a complete foil-bearing body such as a fixed-wing UAV.
2. Drag: This is the force which resists the movement of the UAV through air. In other words, this is the force which opposes the lift forces. The drag generated on an UAV is dependent on the friction between the air and the shape of the UAV. Thus, the drag depends on the shape and size of the wings and other structural components. The biggest drag producing component of an UAV is its fuselage. The drag coefficient is a dimensionless quantity that is used to quantify the drag or resistance of an object in a fluid environment, such as air or water. It is used in the drag equation in which a lower drag coefficient indicates the object will have less aerodynamic or hydrodynamic drag.
In order to provide a UAV which is capable of taking off in short distances, the

shape/geometry/size of the various components have to be optimized in order to increase the lift provided to the structure and reduce the drag faced by the structure. Further, higher lift and lower drag also increases the amount of time the UAV can fly without having to land for refueling or recharging.
While designing such an UAV, the prime consideration is of fluid flow around the UAV during the flight. Flow patterns of the air may be laminar or turbulent. In laminar or streamlined flow, air, at any point in the flow, moves with the same speed in the same direction at all times so that the flow appears to be smooth and regular. In turbulent flow, which is random, chaotic, fluctuating and irregular in nature, the air continuously changes its speed and direction. Turbulent flow leads to high drag. Higher surface roughness of an object causes the nature of airflow to become turbulent which creates greater friction between the fluid layers and ultimately results in greater drag. At low air speeds, the air flow splits when it meets an object and, provided the object is reasonably aerodynamic, the air flows around it, closely following object’s outline. But, if object’s shape is not aerodynamic, then air flow breaks away and becomes turbulent. Hence, it is of utmost importance that the components of the UAV have aerodynamic shape. This assists in maintaining laminar flow of the air around the shape of UAV. This results in reduction of drag which leads to faster ground speed. This ground speed helps the UAV to reach the takeoff velocity early helping the UAV to takeoff in minimum takeoff distance.

In the present invention, in order to achieve this, the structural design of the wings and fuselage has been optimized for achieving high lift and low drag. The main optimizing parameters associated with wing and fuselage are selection of airfoil shape for wings, wing span, wing’s taper ratio, location of control surfaces on the wings, and fuselage aerodynamic design. Numerical analysis/virtual simulations have been carried out for deciding the design parameters. Steady state simulations using CFD modelling with standard k-ἐ turbulent models have been performed for the existing design.
Multiple iterations have been carried out with different configurations of wing and fuselage to ascertain the optimum shapes for these components. During these simulations, standard air density and viscosity with respect to MSL (mean sea level) is taken for the analysis. For CFD analysis of the wing, the inlet boundary conditions with inlet air stream velocity of 23 m/s and atmospheric pressure outlet have been applied. The agreement of the analytical lifting and drag forces with numerical tools is 98%, which is fairly acceptable in design methodology.
The details of how the shapes and design of wing (12, 12A) and fuselage (2) of a fixed wing UAV (1) are finalized along with their benefits are given in following sections.

Design of the Wings of a Fixed Wing UAV: There are a number of aspects to consider, such as the airfoil shape, the taper ratio, and flaps and aileron. These are considered below in details.
1. Airfoil Shape: In an embodiment of the present invention, S1223 airfoil shape (13) is used for the wings (12, 12A). The figure 1 shows the S1223 shape (13) of wings (12, 12A). S1223 airfoil shape (13) falls in the category of NACA (National Advisory Committee for Aeronautics) and S series airfoils, which has a high camber and is capable of generating maximum lift. Use of this airfoil shape helps in increasing the lift produced on the UAV (1) which helps in short distance take off of the UAV (1). But, there is also a disadvantage associated with this airfoil shape that it generates high amount of drag which reduces its endurance. High drag forces are overcome by changing design of wings and effective use of controlling surfaces like Flaps and ailerons. In an exemplary embodiment of present invention, for wings with S1223 airfoil shape (13), aspect ratio between 8 to 12 with MAC (21) (Mean Aerodynamic Chord) length of 190 mm is maintained. The Aspect Ratio of any wing of UAV/aircraft is defined to be the square of the wing span divided by the wing area.
2. Taper Ratio: In order to use the S1223 airfoil shape (13) for wings (12, 12A) and achieve higher lift without compromising drag coefficient of the UAV, multiple

changes in the shape of the wing (12, 12A) have been tried. The inventors during the design iterations used tapered wings. Providing a taper in the wing’s (12, 12A) width leads to reduction in the wing (12, 12A) area which in turn results in reduction in the drag while keeping the lift constant. Taper ratio is the ratio of the root chord (19) and tip chord (20) lengths of wing (12, 12A). This phenomenon occurs as drag is a function of surface area of the wing (12, 12A). Various taper ratios have been tried and verified. There is an optimum taper ratio value for a wing, which has minimum induced drag parameter and maximum Oswald efficiency factor values. In one embodiment of the present invention, a taper ratio of 0.45 has been used. Taper ratio of 0.45 means that if the width of the wing at the toe (near the joint with fuselage or root chord length (19)) is 1 unit then width at the tip (i.e. tip chord length (20)) would be 0.45 units.
The inventors determined that 0.45 is an optimum taper ratio value for a wing (12, 12A) designed with S1223 airfoil shape (13), which minimizes induced drag parameter and maximizes Oswald efficiency factor values. Decreasing taper ratio below 0.45 is found to cause wing-tip stall due to higher local lift coefficients at the tip region of the wing (12, 12A). Meanwhile, increasing the taper ratio above 0.45 proportionately leads to increase in size of wing-tip vortices. Another advantage of choosing the taper ratio of 0.45 is that it reflects an elliptical lift distribution. Taper ratio of 0.45 improves the lift distribution, and reduces the bending moment at the

root of the wing (12, 12A) as its center of mass is closer to the fuselage centerline. The lift distribution results in lower lift-induced drag. The optimum value selected for taper ratio i.e. 0.45 produces least induced drag parameter of 0.01.
CFD modelling for the wing (12, 12A) has been carried out in order to understand the behavior of the S1223 airfoil section (13) with 0.45 taper ratio and taper ratio below and above 0.45. The taper ratio’s less than 0.45 and greater than 0.45 are associated with higher induced drag of more than 0.02 and it gives negative lift distribution at the tip of wing (12, 12A). This may lead to toppling effect.
Induced Drag - The wing tip vortices produce a swirling flow of air behind the wing which is very strong near the wing tips and decreases toward the wing root. The effective angle of attack of the wing is decreased by the induced flow of the vortices and varies from wing tip to wing root. The induced flow produces an additional, downstream-facing, component of aerodynamic force of the wing. This additional force is called induced drag because it faces downstream and has been "induced" by the action of the tip vortices. It is also called "drag due to lift" because it only occurs on finite, lifting wings and the magnitude of the drag depends on the lift of the wing.
Figure 7 shows graph for induced drag parameter vs wing’s (12, 12A) taper ratio for the fixed wing UAV (1) of present invention. Induced drag parameter (δ) is another

single parameter, which represents wing efficiency in terms of induced drag. This parameter depends on only geometry of wing and is independent from angle of attack and lift coefficient. Minimum induced drag for a given lift will occur if taper ratio of wing is a minimum. The fundamental selection of taper ratio is to produce elliptical loading for minimum induced drag. From the graph of figure 7, it is evident that the induced drag parameter is lowest for 0.45 taper ratio of wing (12, 12 A) of fixed wing UAV (1) of present invention.
The stated changes in the UAV (1) design leads to increase in wing (12, 12A) loading. Further changes are required to tackle this problem of higher loads generated on the wings (12, 12A). These changes are explained in next section.
3. Flap and Aileron: In another embodiment of the present invention, to deal with this increased wing loading and to reduce the stalling speed for the wings (12, 12A) with taper ratio of 0.45, length of control surfaces i.e. ailerons has been increased so as to get more effective area of control surfaces to control the roll of the UAV (1). This leads to highly sensitive control surfaces which reduces the effect of stalling of the UAV (1)
However, increasing the length of ailerons leaves no space for the flaps. To overcome this problem, an alternative arrangement has been made which allows

aileron to be used as flaps. Length of control surfaces i.e. flap has been increased so as to get more effective area to generate extra lift in the UAV (1). A flaperon (5) on the UAV's wing (12, 12A) is a type of control surface that combines the functions of both flaps and ailerons on the same linkage. Flaperon (5) as a single control surface on each wing (12, 12A) serves both the purposes of aileron and flap. When flaperons (5) are used as flaps, the left and right flaps are actuated simultaneously and in same direction and when flaperons (5) are used as aileron, left and right ailerons are actuated simultaneously but in opposite direction. The function of using flaperon (5) as flaps and ailerons is not possible simultaneously.
Further, there exists another hurdle, i.e. position of flaperon (5), as this is going to affect the outcome. Various positions have been tried out to find optimum position which results in decreased wing loading. Finally after trying various positions, it is found that flaperons (5) are needed to be placed at the rear or trailing edge of the wing (12, 12 A). Two of the most significant parameters associated with flaperon (5) are hinge line position and flaperon span. Flaperons (5) are located near the tip of the wing, about 5-10 % of tapered wing length away from the tip. The flaperon’s (5) span has to be maintained to be about 55 to 80 % of the wingspan. Wingspan is nothing but the total wing length. In one embodiment of present invention, the flaperon (5) span is 62 % of the wing span. This value is a trade-off with the associated stick forces on wing (12, 12 A) area.

Figure 2 shows top view of first detachable wing (12) of fixed wing UAV (1) of present invention. Figure 3 shows perspective view of second detachable wing (12 A) of fixed wing UAV (1) of present invention. As shown in figures 2 and 3 of present invention, the wings (12, 12 A) with S1223 airfoil shape (13) have taper ratio of 0.45 and the flaperons (5) are present on both wings (12, 12 A).
Design of the Fuselage:
About 30% of the UAV zero-lift drag is due to the aerodynamic shape of the fuselage. While, aerodynamically designing the fuselage, the prime consideration is of fluid flow. At low air speeds, the air flow splits when it meets the fuselage and, provided it is reasonably aerodynamic, the air flows around it, closely following its outline. But, if the shape of fuselage is not aerodynamically correct, then air flow breaks away and becomes turbulent. So it is utmost necessary for a UAV to have a fuselage with good aerodynamic shape. This assists in maintaining laminar flow of the air around it. It should be noted that, generally the fuselage accommodates payload (not shown) and avionics (not shown) of an UAV hence, there is no restriction on its size but, its shape should be aerodynamic so as to minimize drag.
Hence, in the present invention, efficient aerodynamic shape of fuselage (2) has been designed. The aerodynamic design of the fuselage (2) is considered to be a major

aspect of this invention, as it is useful in keeping the drag to be relatively low (ellipsoid streamline body). The aerodynamic shape of fuselage (2) is designed with the help of numerical methods, allowed forces and moments, aerodynamic coefficients, pressure distribution and effective flow separation. Accordingly, the shape of fuselage (2) is designed after multiple design iterations in such a way that the drag coefficient for the fuselage (2) has been reduced to 0.03. This drag coefficient is significantly less in comparison with the drag generated by the whole UAV. So it can be concluded that the fuselage (2) is fully aerodynamically stable.
Using the combined effect of the wings (12, 12 A) with taper ratio 0.45 and S1223 airfoil shape, placement and use of flaperons (5) on wings (12, 12A) and unique aerodynamic design of fuselage (2), a male fixed wing UAV can be converted to short takeoff fixed wing UAV (1) and it can be used in critical territory for image mapping, survey as well as for carriage of stores.
Construction of A Fixed Wing UAV:
How and by which means all the components of fixed wing UAV (1) are manufactured and connected with each other, matters a lot, for overcoming the drawbacks stated in the Background section. Their position with respect to other components also plays a vital role.

Figure 1 shows the fixed wing UAV of current invention, said UAV (1) comprises a aerodynamically shaped fuselage (2); pair of wings (12, 12A) each consisting of flaperon (5) as control surface, at least two wing connector (18) and at least one boom connector (11); tail (10) consisting of rudders (8) and elevators (9) as control surfaces and at least one boom connector (11); propeller (7) with motor (26); landing gears (3, 25) with wheels (4); propulsion systems (not shown); connecting means (14, 18) for connecting wings (12, 12 A) to fuselage (2) and booms (6) for connecting tail (10) to wings (12, 12 A).
Figures 2 and 3 show views of the detachable wings (12, 12 A) of the UAV (1) of the present invention. In an embodiment of present invention, the wings (12, 12 A) are connected to the end portion (17) of fuselage (2) by inserting wing connectors (18) into the fuselage’s holes (24) and attaching them by an inserting pin arrangement (14). The flaperons (5) are either attached to each wings (12, 12 A) by hinge or flaperons (5) are integrally manufactured with each wing (12, 12 A). In integrally manufactured wing (12, 12 A), layers of fiber and resin are put together, then full two cuts on each wing (33) are made at flaperon’s (5) location on integrally manufactured wing (12, 12 A) and partial layers are removed from hinge line of flaperon on wing (30) using cutter blade. This has been done to create flexibility and the hinge movement. Then flaperon (5) is bent repeatedly to create smooth movement as a hinge. The wings (12, 12A) are also equipped with at least one boom connector (11)

which are used to connect tail (10) using booms (6).
The tail (10) of fixed wing UAV (1) is shown in Figure 1 and 6. In an embodiment of present invention, the tail (10) of fixed wing UAV (1) is connected to wings (12, 12 A) via booms (6), boom connectors (11) and insert pin arrangement for tail and wing (27). The tail (10) is also equipped with at least two boom connectors (11) like wings (12, 12 A). The tail (10) comprises two vertical components, namely first vertical component (28) and second vertical component (28 A) and one horizontal component (29). The horizontal component of tail (29) is connected to both first and second vertical component of tail (28, 28 A) at its end. Both first and second vertical components of tail (28, 28 A) are equipped with at least one rudder (8) and at least one boom connector (11). The horizontal component of tail (29) is equipped with at least one elevator (9). The boom connector (11) of first vertical component (28) of tail (10) of fixed wing UAV (1) is connected to one end of boom (6) with insert pin arrangement for tail and wing (27) and other end of same boom (6) is connected to boom connector (11) of first detachable wing (12) with insert pin arrangement for tail and wing (27). Similarly the boom connector (11) of second vertical component (28 A) of tail (10) of fixed wing UAV (1) is connected to one end of another boom (6) with insert pin arrangement for tail and wing (27) and other end of this same boom (6) is connected to boom connector (11) of second detachable wing (12 A) insert pin arrangement for tail and wing (27). Rudders (8) and elevators (9) are either integrally

manufactured with tail (10) or separately manufactured and then joined by hinge to tail (10). In integrally manufactured tail (10), layers of fiber and resin are put together. A full two cuts on tail’s each vertical component (34) of integrally manufactured tail (10) are made at rudder’s (8) location and partial layers are removed from hinge line of rudder on tail’s each vertical component (31) using cutter blade. This is done to create flexibility and hinge movement. Then rudder (8) is bent repeatedly to create smooth movement as a hinge. Similarly full two cuts (35) on tail’s horizontal component (29)of integrally manufactured tail (10) are made at elevator’s (9) location and partial layers are removed from hinge line (32) of elevator on tail’s horizontal component (29)using cutter blade. This is done to create flexibility and hinge movement. Then said elevator (9) is bent repeatedly to create smooth movement as a hinge.
The fuselage (2) of fixed wing UAV (1) is shown in Figure 4 and 5 of present invention. In an embodiment of present invention, fuselage (2) is having a curved nose (15) portion, a central portion (16), and an end portion (17). These portions are connected through smooth curvature for aerodynamic effect. The shape of fuselage (2) is axisymmetric with its nose (15) at front. Fuselage’s (2) shape is smoothly blended avoiding sharp edges. So fuselage (2) is provided with an ellipsoidal nose (15) which has blunt radii (NR). The Length (FL) (22) of fuselage (2) is maintained between 4 to 6 times of its height (FH) (23). Fuselage (2) of fixed wing UAV (1) is

considered as a cockpit. It is made hollow from inside. If the electric propulsion system (not shown) is used then the battery (not shown) is kept inside of nose section (15) of fuselage (2). The avionics like controller (not shown), GPS (not shown), sensors (not shown), antennas (not shown) and receiver (not shown) with required wirings (not shown) are kept inside of central portion (16) of fuselage (2). An ESC (not shown) and motor wires (not shown) are kept inside of end portion (17) of fuselage (2). A motor (26) with propeller (7) is attached to rear end of the end of portion (17) of fuselage (2). At the front end of fuselage (2) speed sensor or pitot tube (no shown) is attached. There are few holes (not shown) for wiring system (not shown) to connect various components present inside and outside of the fuselage (2). The fuselage is also equipped with holes (24) on both upper end portion (17) for inserting wing connectors (18) in to it and attaching them by an inserting pin arrangement (14).
During its operation, fixed wing UAV (1) is equipped with payload (not shown). The payload may include cameras with Gimbal, IR, Night vision and thermal capabilities. Such kind of payload will fit on outer side of fuselage (2) and provisions for these kind of payloads can be made by maintaining balance of fixed wing UAV (2). During the logistic operations, payload will be kept inside of central (16) or end (17) portion of fuselage (2). The fuselage (2) also consists of propulsion system (not shown) inside the central (16) or end portion (17). The propulsion system may be electrically

charged battery operated or fuel ignition type.
In an embodiment of the present invention, the control surfaces i.e. rudders (8), elevators (9) and flaperons (5) are operated through the linkage connected to servo motors (not shown). The precise or desired movement of these control surfaces is controlled with help of controller (not shown) by providing power and signals. These servo motors are working on electric power. In the fixed wing UAV (1), when Flaperons (5) are used as flaps, the left and right flaps are actuated simultaneously and in same direction and when flaperons (5) are used as aileron, left and right ailerons are actuated simultaneously but in opposite direction. The function of using flaperon (5) as flaps and ailerons are not possible simultaneously. Rudder (8) are actuated simultaneously and in same direction. Elevators (9) deflection leads to lift of the UAV (1). Hence, tail (10) is capable of synchronous and differential deflecting.
Wheels (4) are attached to both rear (25) and front (3) landing gears with nut and bolts arrangement and these landing gears (3, 25) are attached to fuselage (2) with nut and bolts arrangement. The front landing gear (3) is attached to bottom of central portion (16) of fuselage (2) while the rear landing gears (25) are attached to bottom of end portion (17) of fuselage (2).
Example Of The Invention

In an exemplary embodiment, fixed wing UAV (1) having size of 1.95 x 0.580 x 1.280 meter shown in Figure 1 has been developed. The said UAV (1) comprises a aerodynamically shaped fuselage (2), pair of wings (12, 12 A) each consisting of flaperon (5) as control surface, at least two wing connectors (18) and at least one boom connectors (11), tail (10) consisting of at least two rudders (8) and at least one elevator (9) as control surfaces and at least two boom connectors (11), propeller (7), landing gears (3, 25) with wheels (4), propulsion systems (not shown), connecting means (14, 18) for connecting wings (12, 12 A) to fuselage (2) and booms (6) for connecting tail (10) to wings (12, 12 A).
The wings (12, 12 A) are connected to end portion (17) of fuselage (2) by inserting wing connectors (18) in to fuselage’s holes (24) and attaching them by an inserting pin arrangement (14) for wing and fuselage. The wings (12, 12 A) with S1223 airfoil shape (13) have taper ratio of 0.45 and the flaperons (5) are present on wings (12, 12 A). The flaperons (5) are placed near the rear or trailing edge or tip of the each wing (12, 12 A). The flaperons (5) are located near tip of wing at a distance of about 5-10 % of tapered wing length. The flaperons (5) are integrally manufactured with each wing (12, 12 A). In integrally manufactured wing (12, 12 A), layers of fiber and resin are put together, then full two cuts on each wing (33) are made at flaperon’s (5) location on integrally manufactured wing (12, 12 A) and partial layers are removed from hinge line of flaperon on wing (30) using cutter blade. This has been done to

create flexibility and the hinge movement. Then flaperon (5) is bent repeatedly to create smooth movement as a hinge. The wings (12, 12 A) have total wing span of 1.85 meter while each wing (12, 12A) have a wing span of 0.925 m. The flaperon’s (5) span is 62 % of the span of corresponding wing (12, 12A). The aspect ratio of wings (12, 12 A) is 10. The Mean Aerodynamic Chord length (21) of wing (12, 12 A) is 190 mm. For these wings (12, 12 A) least induced drag parameter is 0.01 due to taper ratio of 0.45.
The tail (10) of fixed wing UAV (1) is connected to wings (12, 12 A) via booms (6), boom connectors (11) and insert pin arrangement for tail and wing (27). The tail (10) is also equipped with at least two boom connectors (11) like wings (12, 12 A). The tail (10) comprises two vertical components, namely first vertical component (28) and second vertical component (28 A) and one horizontal component (29). The horizontal component of tail (29) is connected to both first (28) and second (28 A) vertical component of tail (28) at its end. Each first and second vertical components of tail (28, 28 A) is equipped with one rudder (8) and one boom connector (11). The horizontal component of tail (29) is equipped with one elevator (9). The boom connector (11) of first vertical component (28) of tail (10) of fixed wing UAV (1) is connected to one end of boom (6) with insert pin arrangement (27) for tail and wing and other end of same boom (6) is connected to boom connector (11) of first detachable wing (12) with insert pin arrangement for tail and wing (27). Similarly the

boom connector (11) of second vertical component (28 A) of tail (10) of fixed wing UAV (1) is connected to one end of another boom (6) with insert pin arrangement (27) for tail and wing and other end of this same boom (6) is connected to boom connector (11) of second detachable wing (12 A) using insert pin arrangement (27) for tail and wing. Rudders (8) and elevators (9) are either integrally manufactured with tail (10) or separately manufactured and then joined by hinge to tail (10). In integrally manufactured tail (10), layers of fiber and resin are put together. A full two cuts on tail’s each vertical component (34) of integrally manufactured tail (10) are made at rudder’s (8) location and partial layers are removed from hinge line of rudder on tail’s each vertical component (31) using cutter blade. This has been done to create flexibility and the hinge movement. Then rudder (8) is bent repeatedly to create smooth movement as a hinge. Similarly full two cuts on tail’s horizontal component (35) of integrally manufactured tail (10) are made at elevator’s (9) location and partial layers are removed from hinge line of elevator on tail’s horizontal component (32) using cutter blade. This has been done to create flexibility and the hinge movement. Then said elevator (9) is bent repeatedly to create smooth movement as a hinge. The tail (10) of fixed wing UAV (1) is connected to wings (12, 12 A) via booms (6) and boom connectors (11). The size of tail (10) is 0.25 x 0.15 x 0.6 meter.
The fuselage (2) of fixed wing UAV (1) is shown in Figure 4 and 5 of present invention. Fuselage (2) is having a curved nose (15) portion, a central portion (16),

and an end portion (17). These portions are connected through smooth curvature for aerodynamic effect and avoiding sharp edges. The shape of fuselage (2) is axisymmetric with its nose (15) at front. The ellipsoidal nose (15) of fuselage (2) has blunt radii (NR) ranging from R10 to R2000 mm. The length of fuselage (FL) (22) is four times of its height (FH) (23). The fuselage (2) is hollow from inside. Due to such aerodynamic design, the drag coefficient for the fuselage (2) has been reduced to 0.03. The battery of electric propulsion system (not shown) which is used to fly the UAV (1) is kept inside of nose section (15) of fuselage (2). The avionic like controller (not shown), GPS (not shown), sensors (not shown), antennas (not shown) and receiver (not shown) with required wirings (not shown) are also kept inside of central portion (16) of fuselage (2). An ESC (not shown) and motor wires (not shown) are kept inside of end portion (17) of fuselage (2). A motor (26) with propeller (7) is attached to rear end of end portion (17) of fuselage (2). At the front end of fuselage (2) speed sensor or pitot tube (not shown) is attached. There are few holes (not shown) for wiring system (not shown) to connect various components present inside the fuselage (2). The fuselage (2) is also equipped with holes (24) on both of its upper end portion (17) for inserting wing connectors (18) in to it and attaching them by an inserting pin arrangement (14). The size of fuselage (2) is 0.14 x 0.18 x 0.7 meter.
The control surfaces i.e. rudders (8), elevators (9) and flaperons (5) are operated

through the linkage connected to servo motors (not shown). The precise or desired movement of these control surfaces is controlled with help of controller (not shown) by providing power and signals. These servo motors are working on electric power. The servo motors used works on 5V. There is an arrangement made to keep these servo motors on or near its respective control surface. Each control surface have its own servo motor. In the fixed wing UAV (1), when flaperons (5) are used as flaps, the left and right flaps are actuated simultaneously and in same direction and when flaperons (3) are used as aileron, left and right ailerons are actuated simultaneously but in opposite direction. The function of using flaperon as flaps and ailerons are not possible simultaneously.
Wheels (4) are attached to both front (3) and rear (25) landing gears with nut and bolts arrangement and these landing gears (3, 25) are attached to fuselage (2) with nut and bolts arrangement. The front landing gear (3) is attached to bottom of central portion (16) of fuselage (2) while the rear landing gears (25) are attached to bottom of end portion (17) of fuselage (2).
The designed fixed wing UAV (1) can carry a maximum takeoff weight (including payload) of up to 8 kg. The UAV (1) of present invention was flight tested. The takeoff distance from zero till the UAV (1) leaves the ground was less than 15 meters without using flaperons (5). Incorporating flaperons (5) in the UAV (1), further

reduces the distance below 8 meters for takeoff weight (including payload) of 6 kg while the takeoff distance reduces below 10 meters for takeoff weight (including payload) of 8 kg. The UAV (1) has endurance of 1 hour and it also has very high glide ratio i.e. 1:16.
All components of fixed wing UAV (1) are made of Carbon Fiber Reinforced Polymers (CFRP) material. Resin infusion is used as manufacturing method to produce all components of fixed wing UAV (1). Few components of fixed wing UAV (1) mainly an aerodynamically shaped fuselage (2), first and second detachable wing (12, 12 A), tail (10) and pair of booms (6) are made as single piece from Carbon Fiber Reinforced Polymers (CFRP) material and using resin infusion method. In exemplary embodiment, fuselage (2) is manufactured in single piece. Each detachable wing (12, 12 A) is manufactured in single piece. The tail (10) is manufactured in single piece. Each boom (6) is manufactured in single piece.
The fixed wing UAV (1) of the present invention has capability to perform autonomous flight. Hence, it has controller (not shown) with the receiver on board as well as the telemetry link for communication and feedback of telemetry data. The controller is programmed before flight for way point navigation and fly by wire modes. The precise or desired movement of control surfaces (5, 8, and 9) is controlled with help of controller by providing power and signals to servo motors.

Advantages Of The Invention
1. The addition of flaperon (5) as a control surface on a tapered wing having S1223 airfoil section (13) with taper ratio 0.45 results in reducing the takeoff distance of the UAV substantially. Using the above combination of inventive design modifications, the takeoff distance for a fixed wing UAV can be reduced below 10 meter.
2. Another advantage of this design of short take-off Fixed wing UAV (1) is high glide ratio which is 1:16. Normally, UAV having glide ratio of 1:15 are considered as good gliders. This means, while in flight when the propulsion is switched off, the craft travels at least 15 units for the descent of 1 unit.
3. A Fixed Wing UAV (1) with aerodynamically designed fuselage (2), wings (12, 12 A) with S1223 airfoil shape (13) and 0.45 taper ratio, and using flaperons (5) takes off at short distance which makes it useful in the areas where flat terrain is not available for takeoff.
The technical advancement of this invention lies in providing aerodynamically designed fuselage (2) along with use of flaperon (5) on tapered wing (12, 12 A) having taper ratio 0.45 so that UAV (1) can takeoff at short distance i.e. below 10 meters. Furthermore, this system uses an innovative step-wise combination of: a) aerodynamic shape of fuselage; b) tapered wing; and c) use of flaperon; to achieve a

short distance takeoff.
Although this specification describes this invention in relation to short distance takeoff, it is to be understood that the same invention, without departing from its inventive concept, can be used in short distance landing.
While this detailed description has disclosed certain specific embodiments of the present invention for illustrative purposes, various modifications will be apparent to those skilled in the art which do not constitute departures from the spirit and scope of the invention as defined in the following claims, and it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the invention and not as a limitation.

We claim:
1. A fixed-wing unmanned aerial vehicle (UAV) (1) comprising:
- afuselage (2);
- a first detachable wing (12) connected to said fuselage (2);
- a second detachable wing (12 A) connected to said fuselage (2);
- a propulsion system consisting of a battery and a propeller (7) with motor (26), said propeller (7) with motor (26) connected to rear end of said fuselage (2);
- a tail (10) connected to both said first detachable wing (12) and said second detachable wing (12 A) using pair of booms (6), wherein said tail (10) is equipped with rudders (8) and elevator (9);
- a front landing gear (3) having wheel (4) connected to bottom of said fuselage (2);
- a rear landing gear (25) having pair of wheels (4) connected to bottom of said fuselage (2); and
characterized in that said both first detachable wing (12) and second detachable wing (12 A) have S1223 airfoil shape with taper and are each equipped with a flaperon (5).
2. The fixed-wing UAV as claimed in claim 1, wherein said flaperons (5) are
placed near the rear or trailing edge of said wing (12, 12 A) and are located at
a distance of about 5-10 % of tapered wing length from tip of wing (12, 12 A).

3. The fixed-wing UAV (1) as claimed in claims 1-2, wherein said flaperon’s (5) span is in between 55 to 80 % of wings span preferably said flaperon’s span is 62% of wings span.
4. The fixed-wing UAV as claimed in claims 1-3, wherein said both first detachable wing (12) and second detachable wing (12 A) have taper ratio of 0.45.
5. The fixed-wing UAV (1) as claimed in claims 1-4, wherein said both first detachable wing (12) and second detachable wing (12 A) have aspect ratio in the range of 8 to 12 preferably 10.
6. The fixed-wing UAV (1) as claimed in claims 1-5, wherein said both first detachable wing (12) and second detachable wing (12 A) have Mean Aerodynamic Chord length (21) of 190 mm.
7. The fixed-wing UAV (1) as claimed in claims 1-6, wherein said each first detachable wing (12) and second detachable wing (12 A) have wing span of 0.925 meters.
8. The fixed-wing UAV as claimed in claims 1-7, wherein said both first detachable wing (12) and second detachable wing (12 A) are equipped with at least two wing connectors (18) and at least one boom connector (11).
9. The fixed-wing UAV as claimed in claims 1-8, wherein said fuselage (2) has a

curved nose portion (15), a central portion (16), and an end portion (17), and said central portion (16) is connected to said nose portion (15) on one side and to said end portion (17) on the other side through smooth curvature.
10. The fixed-wing UAV as claimed in claims 1-9, wherein an ellipsoidal nose of curved nose portion (15) of said fuselage (2) has blunt radii ranging from R10 to R2000 mm.
11. The fixed-wing UAV as claimed in claims 1-10, wherein the length (22) of said fuselage (2) is four times of height (23) of said fuselage (2).
12. The fixed-wing UAV (1) as claimed in claims 1-11, wherein said first and second detachable wings (12, 12 A) are connected to both sides of said upper end portion of fuselage (17) by inserting said wing connectors (18) of each wing (12, 12 A) in to fuselage’s holes (24) present at both sides of said upper end portion of fuselage (17) and attaching said wing connectors (18) by an inserting pin arrangement (14) with fuselage (2).
13. The fixed-wing UAV (1) as claimed in claims 1-12, wherein said boom connector (11) of first vertical component (28) and second vertical component (28 A) of tail (10) is used to connect said boom connectors (11) of said first detachable wing (12) and said second detachable wing (12 A) respectively using booms (6) and insert pin arrangement (27).
14. The fixed wing UAV (1) as claimed in claims 1-13, wherein said UAV (1)

carry a takeoff weight up to 8 kg including payload and the takeoff distance from zero till said UAV (1) leaves the ground is less than 10 meters.