Abstract:
Aircraft systems that are optimized for multiple phases of flight are disclosed. In an aspect, an in-line staged aircraft is disclosed comprising a launch vehicle and a flight vehicle which are configured to join together along a common center line and form a single air foil in the joined configuration. The flight vehicle and the launch vehicle are separable in flight. In an aspect, the flight vehicle is an unmanned aerial vehicle configured for high-altitude, long-endurance operations.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS AND PATENTS 
       [0001]    This application claims the benefit of U.S. Provisional Patent Application No. 61/735,351, filed Dec. 10, 2012, and entitled “In-Line Stages Horizontal Takeoff Vehicle”, the entire contents of which is incorporated herein by reference. 
         [0002]    The subject matter of this application is related to U.S. Pat. No. 8,528,853 and to U.S. Design Pat. No. D 677,613. 
     
    
     FIELD OF THE DISCLOSURE 
       [0003]    The present disclosure generally relates to aerospace vehicles and more particularly to multi-stage atmospheric vehicles, spacecraft, and methods of operating such vehicles. 
       BACKGROUND 
       [0004]    In aerospace generally and aviation in particular, reducing the total fuel and equipment required to achieve a desired velocity, altitude, or operational envelope has long been sought. 
         [0005]    Improving Operational Abilities 
         [0006]    A variety of approaches have been taken to improve the operational abilities of aerospace vehicles. For example, many modern airplane fuselages are configured as monocoque or semi-monocoque structures wherein the exterior surface of the fuselage is also the primary load bearing member. This increases strength of the airplane while reducing the mass required for maintaining structural integrity. Thus, more mass can be devoted to useful payload (e.g., cargo, personnel, remote sensing equipment, weaponry, navigation equipment, communications equipment, fuel, and the like). Refinement, streamlining, and use of more efficient engines and wing profiles in modern aircraft (e.g., the Boeing 747®, available from The Boeing Company of Seattle, Wash.) has enabled vehicles with a useful payload fraction of 45 to 55%. Payload fraction, the measure of payload and fuel mass compared to total vehicle mass, has nearly doubled since the days of early propeller-driven aircraft. 
         [0007]    While modern aircraft are very efficient, their design is optimized for taking off, ascending to a desired altitude, performing the required actions (e.g., crossing an ocean, surveilling an area), descending, and safely landing. Because aircraft are optimized for the entire flight path, they often do not achieve maximum efficiency during every stage of their operation. For example, an aircraft may be extremely efficient when landing, but inefficient when performing aerial surveillance from 50,000 feet. 
         [0008]    Multi-stage vehicles partially address optimizing aerospace vehicle for their entire flight path. Multi-stage vehicles have long been used to efficiently transport and deliver payloads. A typical multi-stage vehicle comprises at least two stages, stacked one on top of the other. Each stage contains engines and propellant. The upper stage(s) contain operational payloads such as the crew, remote sensing equipment, weaponry, and the like. At launch, the first stage fires, lifting the vehicle into the air. Once the first stage runs out of propellant, it is jettisoned and the second stage ignites, carrying the payload to the desired location (e.g., a low earth orbit, an apogee, and the like). By jettisoning the lower stage(s) after it ceases operation, the vehicle reduces the remaining mass that must be carried to the desired location. Thus, the vehicle may use less fuel to get to the desired location. This also enables transport of larger payloads in the upper stage. Some multi-stage vehicles, like the Saturn V (operated by the National Aeronautics and Space Administration) or the Titan family of vehicles (operated by the United States Air Force, among others) utilize expendable stages. That is, each stage of the vehicle is designed for a single use. After this use the stage is jettisoned and destroyed or abandoned. While these vehicles may be optimized for each portion of their flight path, discarding stages after a single use is costly and severely curtails operational readiness because an entire new vehicle must be constructed and assembled after each use. 
         [0009]    Other multi-stage vehicles, like the Space Shuttle (operated by the National Aeronautics and Space Administration), are partially reusable. That is, one or more stages of such vehicles are recovered and used again. While these vehicles avoid wasting the recovered stages, operational readiness is limited because of the significant processing time in between flights. Atlantis experienced the quickest turnaround of a Shuttle orbiter, as only 54 days lapsed between its launch on STS-51J and its launch on STS-61 B. Shuttle orbiter processing times were significant for many reasons, including the following: the Space Shuttle external tank (ET) was a single-use item, requiring a new ET to be built and tested for each flight; reusable portions of the Space Shuttle had to be recovered from their landing in the ocean; and the Space Shuttle was assembled and launched vertically, limiting the locations from which it could be processed and launched. 
         [0010]    Shuttle orbiters, such as Atlantis, are lifting bodies, optimized for reentering the atmosphere and landing horizontally on a runway. The Space Shuttle is not optimized for other portions of the vehicle&#39;s flight path, however, because the orbiter does not provide aerodynamic lift during takeoff. 
         [0011]    Emergence of Drone Aircraft 
         [0012]    Unmanned and armed aircraft are known as “combat drones”. Such vehicles operate autonomously or semi-autonomously, flying to or from areas of interest with little or no human direction. Such vehicles may be remotely controlled by a pilot located off board the aircraft for use in combat zones. Combat drones may be controlled from remote locations several thousand miles away from their intended target, with a lag-time, or ‘latency,’ of only a few seconds. This unmanned style of combat has increased since its introduction in the early 2000s; an estimated 6,300 combat drones are currently used by the United States across the world. 
         [0013]    Unmanned and unarmed aircraft are known as “surveillance drones”. Such vehicles may be autonomously controlled by onboard computers, may be under the remote control of an off board pilot, or may be controlled by a combination of the two. Surveillance drones may be used for surveillance by law enforcement and other government agencies within its own borders. The surveillance drone can also be used for stealth, data-gathering missions in combat zones. The elimination of a human pilot from the surveillance drone allows the aircraft to “loiter” in an area of interest for a significantly longer time than possible with an on-site human operator because the drone is not constrained by the physiological limits of a human pilot. 
         [0014]    Surveillances drones are advancing in onboard technology offered, including onboard cameras with infrared technology, heat sensors and facial recognition capabilities. 
         [0015]    Currently, the most advanced drones under development may takeoff using onboard jet engines. Once the drone reaches station altitude, the jet engine is powered-down, and the drone enters electric power mode. In electric power mode, the drone stays aloft via solar rechargeable electric battery-powered motors and propellers, and the engine provides no utility for the drone. In fact, the engine and fuel tanks are a detriment because such components have a significant mass and take up a significant amount of room within the cramped drone. Holding the dormant jet engine aloft places some drain on the drone&#39;s electric battery store. 
         [0016]    Given the foregoing, what is needed are devices and methods which facilitate optimization of an aerospace vehicle during some or all phases of flight. Devices and methods which enable land-based recovery and reintegration of staged aerospace vehicles and aircraft are also needed. In particular, facilitating such recovery and reintegration without extensive ground support equipment is desired. 
         [0017]    Additionally, devices and methods are needed which enable drones to: achieve a station altitude without an onboard jet engine or fuel tanks; reach station altitude with no power drain; and remain on station longer. 
       SUMMARY 
       [0018]    This Summary is provided to broadly introduce concepts that are described in detail below in the Detailed Description section. This Summary is not intended to identify key features or essential features of the disclosures subject matter, nor is this Summary intended as an aid in determining the scope of the disclosed subject matter. 
         [0019]    Aspects of the present disclosure meet the above defined needs by providing devices and methods which facilitate aerospace vehicles optimized for one or more phases of the vehicle&#39;s flight. In particular, such needs are met via providing and operating a multi-stage aerospace vehicle (e.g., an aircraft, a spacecraft, and the like) configured for horizontal takeoff and landing and wherein more than one stage of the vehicle provides aerodynamic lift during atmospheric flight. An aerospace vehicle&#39;s flight may include, but is not limited to the following phases: takeoff, ascent, station altitude operation, descent, and landing. 
         [0020]    As described above, multi-stage vehicles offer benefits over single stage vehicles. During a given phase of flight, multi-stage vehicles enable an aerospace vehicle to perform in a manner more closely tailored to the unique demands and opportunities of that flight phase. For example, a multi-stage vehicle such as the Space Shuttle consists of an orbiter portion designed to reduce the fuel needed to safely land. The Shuttle orbiter is configured as a lifting body, thereby enabling the orbiter to glide to a safe landing during the descent and landing phases of its flight. 
         [0021]    In an aspect, a multi-stage aircraft is provided which is optimized for multiple phases of the vehicle&#39;s flight. The multi-stage aircraft comprises a launch vehicle and a flight vehicle and may takeoff horizontally. The front portion of the launch vehicle is configured to removably connect to the rear portion of the flight vehicle such that the two portions act as a single aircraft when connected. In this manner, the multi-stage aircraft is horizontally staged. The launch vehicle and the flight vehicle may separate during flight. 
         [0022]    The launch vehicle comprises one or more engines (e.g., bi-propellant rocket engine, solid rocket motor, turbojet engine, turboprop engine, and the like) configured to provide sufficient power to enable powered flight of the multi-stage aircraft. 
         [0023]    The launch vehicle and the flight vehicle each comprise wing portions configured to provide lift during atmospheric flight. The wing portions of the launch vehicle are configured to allow the launch vehicle to fly without being connected to the flight vehicle. Similarly, the wing portions of the launch vehicle are configured to allow the flight vehicle to fly without being connected to the launch vehicle. 
         [0024]    When the launch vehicle and the flight vehicle are connected, the wing portions of the launch vehicle and the wing portions of the flight vehicle each provide lift. In an aspect, the wing portions of the launch vehicle and the wing portions of the flight vehicle create a continuous wing when the launch vehicle and the flight vehicle are connected. That is, the wing portions act as a single unit and are spaced sufficiently closely (e.g., touching, separated by inches, separated by a small distance relative to the size of the wings) that laminar flow of air is maintained over the wings. The generation of force from both stages of the multi-stage aircraft optimizes the takeoff and ascent phases of flight as compared to other multi-stage vehicles. For example, the stages of the Titan family of rockets provide no aerodynamic lifting forces during any phase of flight; such rockets may only gain altitude via propulsive forces. While the Space Shuttle orbiter is configured to provide lift, the configuration of the Space Shuttle at launch does not enable the generation of lifting forces during the takeoff and ascent phases of flight. Typical horizontal launch vehicles either mask the wings to reduce drag, losing the lift of that craft, or stack two aircraft, producing greater frontal area and drag. 
         [0025]    Upon reaching a desired altitude or position, the launch vehicle and the flight vehicle may separate. The wing portion of the flight vehicle provides lift for the now separated flight vehicle, enabling it to stay aloft. The flight vehicle comprises one or more engines configured to facilitate powered flight of the flight vehicle. The flight vehicle wing portions are configured to provide sufficient lift at a desired station altitude that one or more small engines may be used to maintain the flight vehicle&#39;s altitude. In an aspect, the flight vehicle wings provide sufficient lift and the flight vehicle engines provide sufficient power to maintain its altitude however the vehicle lacks sufficient power to takeoff without the assistance of the launch vehicle. In this manner, the flight vehicle is optimized for the station altitude operation, descent, and landing portions of the flight. Energy consumption of the flight vehicle is reduced for extended duration. 
         [0026]    After separation, the launch vehicle may descend and land horizontally on a runway. Similarly, after performing desired tasks, the flight vehicle may descend and land horizontally on a runway. Because both the launch vehicle and the flight vehicle comprise engines, they may fly to and land at any airstrip. After landing, the launch vehicle and any other compatible flight vehicle may be easily reconnected and re-equipped for another flight, enabling reusability while reducing processing time. In an aspect, the flight vehicle is equipped with engines which are sufficiently powerful to keep the flight vehicle aloft, but lack the power to allow the vehicle to take off under its own power (i.e., without being attached to the launch vehicle). 
         [0027]    In some aspects of the present disclosure, the flight vehicle is an unmanned drone. The flight vehicle may be configured as a high-altitude, long-endurance (HALE) drone. In other aspects of the present disclosure, the launch vehicle is an unmanned drone. 
         [0028]    Where the flight vehicle is a drone, the mid-flight removal of the powerful engines necessary for the flight vehicle to ascend to an operational altitude and travel to an operational area enables a higher fraction of the drone&#39;s payload to be devoted to useful equipment (e.g., cargo, personnel, remote sensing equipment, weaponry, navigation equipment, communications equipment, fuel, and the like). 
         [0029]    Further features and advantages of the present disclosure, as well as the structure and operation of various aspects of the present disclosure, are described in detail below with reference to the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0030]    The features and advantages of the present disclosure will become more apparent from the Detailed Description set forth below when taken in conjunction with the drawings in which like reference numbers indicate identical or functionally similar elements. 
           [0031]      FIG. 1  is a perspective view of a multi-stage aircraft in a separated configuration, according to an aspect of the present disclosure. 
           [0032]      FIG. 2  is a perspective view of a multi-stage aircraft in a joined configuration, according to an aspect of the present disclosure. 
           [0033]      FIG. 3  is a side view of a launch vehicle with the launch vehicle landing gear deployed, according to an aspect of the present disclosure. 
           [0034]      FIG. 4  is a perspective view of a flight vehicle, according to an aspect of the present disclosure. 
           [0035]      FIG. 5  is a side view of a multi-stage aircraft in a joined configuration with the launch vehicle landing gear deployed, according to an aspect of the present disclosure. 
           [0036]      FIG. 6  is a flowchart of a method of deploying a flight vehicle and recovering a launch vehicle, according to an aspect of the present disclosure. 
           [0037]      FIG. 7  is a perspective view of a multi-stage aircraft, in a separated configuration, according to an aspect of the present disclosure. 
           [0038]      FIG. 8  is a perspective view of a multi-stage aircraft, in a joined configuration, according to an aspect of the present disclosure. 
           [0039]      FIG. 9  is a perspective view of a multi-stage aircraft, in a separated configuration, wherein the multi-stage aircraft is configured to deploy the flight vehicle to space, according to an aspect of the present disclosure. 
           [0040]      FIG. 10  is a perspective view of a multi-stage aircraft, in a joined configuration, wherein the multi-stage aircraft is configured to deploy the flight vehicle to space, according to an aspect of the present disclosure. 
           [0041]      FIG. 11  is side view of the flight vehicle wherein the flight vehicle wings are angled upward, according to an aspect of the present disclosure. 
           [0042]      FIG. 12  is a side view of the flight vehicle wherein the flight vehicle wings are angles to facilitate altering the trajectory of the flight vehicle, according to an aspect of the present disclosure. 
       
    
    
     DETAILED DESCRIPTION 
       [0043]    The present disclosure is directed to systems and methods which facilitate aerospace vehicles optimized for one or more phases of the vehicle&#39;s flight. In particular, multi-stage aircraft are disclosed and methods of operating such aircraft are disclosed wherein the aircraft is configured for horizontal takeoff and landing and wherein more than one stage of the aircraft provides aerodynamic lift during atmospheric flight. In aspects of the present disclosure, the wings of each stage are positioned sufficiently closely (e.g., touching, separated by inches, separated by a small distance relative to the size of the wings) when the stages of the vehicle are connected such that they operate as a single wing. That is, in some aspects, the wings form a single wing and airflow remains laminar over the entirety of the joined wing. An aircraft&#39;s flight may include, but is not limited to the following phases: takeoff, ascent, station altitude operation, descent, and landing. 
         [0044]    In an aspect, such multi-stage aircraft enables the positioning of a high-altitude, long-endurance drone at a desired altitude and location while reducing the energy required to bring the drone to the desired location and increasing the payload space available for operations equipment (e.g., cargo, remote sensing equipment, weaponry, navigation equipment, communications equipment, fuel, and the like). 
         [0045]    For the purposes of this disclosure, the term “aircraft” is a single or multi-stage vehicle capable of powered or unpowered flight. The term includes, but is not limited to, aerospace vehicles, airplanes, gliders, sailplanes, spacecraft, lifting bodies, or other vehicle capable of flight. As will be appreciated by those skilled in the relevant art(s) after reading the description herein, one or more stages of the multi-stage aircraft disclosed may be configured for operation in space (e.g., suborbital operation, orbital operation, and the like). 
         [0046]    Reference may be made to the front, back, left, right, top, and bottom portions of the aircraft. For the purposes of the present disclosure, the front portion of an item described (e.g., a flight vehicle, a launch vehicle, and the like) is that portion of the item which leads during flight. The top portion of an item described is that portion of the item which appears higher than other portions when the aircraft is taxing. The left side of an item described is that portion of the item which appears on the left when the aircraft is viewed from above and its nose is pointing forward. It is understood that such terms are used to clarify the present disclosure. The present disclosure should not be limited by such usage. 
         [0047]    As will be readily apparent to those skilled in the relevant art, aspects of the present disclosure may possess right halves and left halves that are substantially identical. That is, the aircraft may be symmetrical in that the right half of the aircraft is a mirror image of the left half thereof. Accordingly, reference may be variously made to only the right side or the left side of the aircraft. It will be understood that the other side of the device, while not specifically described, is constructed and functions in a similar manner to the portions described. 
         [0048]    Referring now to  FIG. 1 , a perspective view of a multi-stage aircraft  102  in a separated configuration, according to an aspect of the present disclosure, is shown. 
         [0049]    In an aspect, aircraft  102  is optimized for multiple phases of the flight. Aircraft  102  comprises a launch vehicle  104  and a flight vehicle  106  and may takeoff horizontally. The launch vehicle front portion  108  is configured to removably connect to the flight vehicle rear portion  110  such that the two portions act as a single aircraft when connected. In this manner, aircraft  102  is horizontally staged. 
         [0050]    Launch vehicle  104  and flight vehicle  106  may separate during flight. Launch vehicle  104  and flight vehicle  106  are removably connected in a manner that facilitates in-flight transition from a joined configuration (as shown in  FIG. 2 ) to a separated configuration (as shown in  FIG. 1 ). Flight vehicle rear portion  110  is configured to approximately conform to launch vehicle front portion  108 . Thus, when aircraft  102  is in a joined configuration, flight vehicle  106  and launch vehicle  104  form a single airfoil. In an aspect, a single airfoil is formed by the positioning of launch vehicle wing portions adjacent to flight vehicle wing portions. Positioning is sufficiently close (e.g., contacting, spaced a short distance) that the wing portions act as a single airfoil. Flight vehicle rear portion  110  and launch vehicle front portion  108  may comprise connectors (not shown in  FIG. 1 ) which removably engage when aircraft  102  is in a joined configuration. In an aspect, such connectors are explosive bolts. In another aspect, the trailing edge of flight vehicle  106  wing portions may interconnect with launch vehicle front portion. 
         [0051]    In another aspect, such connectors are reusable and may be reengaged in-flight or in between flights. Connectors may be hydraulic clamps, grapplers, and the like. 
         [0052]    Launch vehicle  104  and flight vehicle  106  each comprise wing portions configured to provide lift during atmospheric flight. The wing portions of launch vehicle  104  are configured to allow launch vehicle  104  to fly without being connected to flight vehicle  106 . Similarly, the wing portions of flight vehicle  106  are configured to allow flight vehicle  106  to fly without being connected to launch vehicle  104 . 
         [0053]    In an aspect, launch vehicle  104  is configured as a blended body vehicle and comprises launch vehicle wings  112  (labeled, for clarity, as launch vehicle wings  112   a  and  112   b  in  FIG. 1 ). Launch vehicle wings  112  may have a moderate or low aspect ratio. Where launch vehicle wings  112  have such aspect ratios, aircraft  102  may still comprise a combined airfoil with a high aspect ratio (as shown in  FIG. 1 ) while enabling flight vehicle wings  114  (labeled, for clarity, as flight vehicle wings  114   a  and  114   b  in  FIG. 1 ) to have high aspect ratio wings optimized for high-altitude, long-endurance flight. 
         [0054]    Where flight vehicle  106  is a high-altitude, long-endurance drone, it may be configured for optimal operation during the station altitude phase of flight. Flight vehicle may be configured as a flying wing. In such an aspect, flight vehicle wing  114  encompasses a substantial portion of flight vehicle structure. 
         [0055]    Flight vehicle wings  114  may be configured for optimal operation during the station altitude operation phase of flight. At high altitudes, long, slender wings are often preferable because of their high aerodynamic efficiency, large wing area, and low drag. However, such wings tend to be very flexible and fragile. Flight vehicle  106  may maintain the large wing area of a vehicle with long slender wings via incorporation of two airfoils. Flight vehicle  104  may comprise two flight vehicle wings  114 . In an aspect, flight vehicle wings  114  are configured as swept back airfoils. In another aspect, such as the aspect depicted in  FIG. 4 , flight vehicle wings  114  are configured as flying wings. 
         [0056]    Flight vehicle wings  114  may have a thickness which enables payloads to be housed within the wing. Such a design is akin to flying wing aircraft. 
         [0057]    In order to increase rigidity, lower flight vehicle wing  114   a  and upper flight vehicle wing  114   b  may be joined at the tip portions of such flight vehicle wings  114 . Structural advantage is provided by the “truss” structure form where the upper and lower wings join as a triangle or joined wing configuration. Flight vehicle  106  may further comprise a strut  116 . Strut  116  is configured to increase structural integrity of flight vehicle. Strut may interconnect lower flight vehicle wing  114   a  and upper flight vehicle wing  114   b.  A first portion of strut  116  is connected to the top of lower flight vehicle wing  114   a.  A second portion of strut  116  is connected to the bottom of upper flight vehicle wing  114   b.    
         [0058]    Flight vehicle wings  114  may be arranged in a backwards stagger configuration. In another aspect, flight vehicle wings  114  may be arranged in a forward stagger configuration or upper flight vehicle wing  114   b  may be positioned directly above lower flight vehicle wing  114   a.    
         [0059]    In other aspects, flight vehicle wings  114  and launch vehicle wings  112  may have different aspect ratios (e.g., low, moderate, and high), wing sweeps (e.g., swing-wing, forward swept, swept, straight, and the like), or multiple wings (e.g., biplane). As will be appreciated by those skilled in the relevant art after reading the description herein, flight vehicle wing  114  and launch vehicle wing  112  configurations may be chosen to enable desired operational capabilities and may be optimized for both joined configuration functionality and separated configuration functionality. 
         [0060]    As will be appreciated by those skilled in the relevant art after reading the description herein, flight vehicle  106  and launch vehicle  104  may further comprise control surfaces (not labeled, for clarity, in  FIG. 1 ) adapted for, for example, atmospheric flight. 
         [0061]    Referring now to  FIG. 2 , a perspective view of multi-stage aircraft  102  in a joined configuration, according to an aspect of the present disclosure, is shown. 
         [0062]    Aircraft  102  may be configured to takeoff and fly to a desired station location and altitude in the join configuration shown in  FIG. 2  before entering the separated configuration shown in  FIG. 1 . Flight vehicle  106  may comprise one or more engines  202 . Engine  202  may be propeller-driven engine, such as a turboprop engine or electrically driven propeller. Propeller-driven engines may be configured for quiet operation, enabling deployment of unmanned, drone flight vehicles  106  into hostile areas of interest. In other aspects, engine  202  may be a rocket engine, turbojet engine, turboprop engine, or the like. 
         [0063]    Engine  202  may remain inactive until flight vehicle  106  detaches from launch vehicle  104 . In another aspect, engine  202  activates prior to separation and may provide additional power for flight and separation of flight vehicle  106  and launch vehicle  104 . 
         [0064]    When the launch vehicle  104  and the flight vehicle  106  are connected, the wing portions of launch vehicle  104  and the wing portions of flight vehicle  106  each provide lift. The generation of force from both stages of aircraft  102  optimizes the takeoff and ascent phases of flight as compared to other multi-stage vehicles. For example, the stages of the Titan family of rockets provide no aerodynamic lifting forces during any phase of flight; such rockets may only gain altitude via propulsive forces. While the Space Shuttle orbiter is configured to provide lift during the landing phase, it does not generate lifting forces during the takeoff and ascent phases of flight. 
         [0065]    Upon reaching a desired altitude or position, launch vehicle  104  and flight vehicle  106  may separate. The wing portion of flight vehicle  106  provides lift for the now separated flight vehicle  106 , enabling it to stay aloft. Flight vehicle  106  may comprise one or more engines configured to facilitate powered flight. Flight vehicle wing portions are configured to provide sufficient lift at a desired station altitude that one or more small engines may be used to maintain flight vehicle&#39;s altitude. In an aspect, the flight vehicle wings provide sufficient lift and the flight vehicle engines provide sufficient power to maintain its altitude however the vehicle lacks sufficient power to takeoff without the assistance of launch vehicle  104 . In this manner, flight vehicle  106  is optimized for the station altitude operation, descent, and landing portions of the flight. 
         [0066]    After separation, launch vehicle  104  may descend and land horizontally on a runway. Similarly, after performing desired tasks, flight vehicle  106  may descend and land horizontally on a runway. Because both launch vehicle  104  and flight vehicle  106  comprise engines, they may fly to and land at any airstrip. After landing, launch vehicle  104  and flight vehicle  106 , or any other compatible vehicle, may be easily reconnected and re-equipped for another flight, enabling reusability while reducing processing time. 
         [0067]    Referring now to  FIG. 3 , a side view of launch vehicle  104  with launch vehicle landing gear  302  deployed, according to an aspect of the present disclosure, is shown. 
         [0068]    Launch vehicle  104  comprises one or more main engines (e.g., rocket engine, turbojet engine, turboprop engine, and the like) configured to provide sufficient power to enable powered flight of aircraft  102  (not shown in  FIG. 3 ). 
         [0069]    The main engine may be an air-breathing system, such as a turbojet engine. In such aspects, an intake  202  is provided on launch vehicle  104  front. Intake  202  is configured to channel atmosphere into the main engine. Main engine exhaust exits launch vehicle  104  via one or more exhaust ports  204 . Exhaust port  204  may be configured to reduce its radar and thermal signature. In another aspect, exhaust port  204  may be gimbaled, to assist launch vehicle maneuverability. In yet another aspect, exhaust port  204  has a variable geometry, configured to optimize the efficiency of the main engine at various thrust levels. 
         [0070]    In the joined configuration, aircraft  102  may weigh more than the combined airframe can lift utilizing launch vehicle  104  main engines. In order to facilitate takeoff of aircraft  102  in a joined configuration, launch vehicle  104  may further comprise assist motors  206  (labeled, for clarity, as assist motors  206   a  and  206   b  in  FIG. 3 ). Assist motors  206  operate in a fashion similar to Rocket-Assisted Take Off systems, also known as JATO, RATO, and RATOG systems. Typically, cargo planes, such as the C-130 (available from Lockheed Martin of Bethesda, Md.) or drones such as the BQM-74 (available from Northrop Grumman of West Falls Church, Va.) are launched by operating such vehicle&#39;s main engines at full thrust and firing attached rocket motors during takeoff, in order to provide additional thrust. In an aspect of the present disclosure, assist motors  206  are solid rocket motors. During takeoff, the main engines are operated at full thrust and assist motors  206  are fired in order to provide additional takeoff thrust. Assist motors  206  may be modular, enabling rapid replacement of spent assist motors  206 . 
         [0071]    Launch vehicle  104  may comprise deployable landing gear (labeled, for clarity, as landing gear  302   a - 302   c  in  FIG. 3 ). Launch vehicle landing gear  302  may be configured to support aircraft  102  in a joined configuration during takeoff. In some embodiments, launch vehicle landing gear  302  may be configured to support aircraft  102  in a joined configuration during landing. Such a configuration may be desirable where flight vehicle  106  does not comprise landing gear and aircraft  102  mission must be aborted. Such landing gear enables recovery of landing gear-less flight vehicles. 
         [0072]    Referring now to  FIG. 4 , a perspective view of flight vehicle  106 , according to an aspect of the present disclosure, is shown. 
         [0073]    Aircraft  102  may be designed to deliver a portion of the device, namely flight vehicle  106 , to an operational area so that flight vehicle  106  may carry out a mission (e.g., surveillance, transportation, and the like). One or more portions of flight vehicle  106  may be configured to carry a payload. Flight vehicle wings  114  may comprise payload areas suitable for fuel, observation equipment, and the like. Flight vehicle wings may comprise central portions  404  (labeled, for clarity, as central portions  404   a  and  404   b  in  FIG. 4 ). Central portion  404  may be significantly thicker than other portions of flight vehicle wing  114 , creating a volume suitable for accommodating payloads. 
         [0074]    Flight vehicle  106  may comprise payload pods  402  (labeled, for clarity, as payload pods  402   a, b  in  FIG. 4 ). Payload pod  402  may house removable, deployable, or other payloads. In an aspect, payload pod  402  houses engine  202 . In another aspect, one or more payload pods  402  may comprise a door, enabling payloads to be exposed to the surrounding environment or released after the door is opened. 
         [0075]    Referring briefly now to  FIG. 5 , a side view of aircraft  102  in a joined configuration with landing gear  302  deployed, according to an aspect of the present disclosure, is shown. 
         [0076]    In a joined configuration, the centerline of lower flight vehicle wing  114   a  and launch vehicle wings  112  overlap, creating a single airfoil. In this configuration, intake  202  is exposed to the atmosphere and may feed air to launch vehicle  104  main engines. The joined wing drone stage of  FIGS. 4 and 5  offer a high altitude long endurance drone that also features a truss type structure for light weight and durability during launch operations. The truss type triangulated wings offer strength for the thin airfoil of a sail plane in a short wingspan. A folding propeller system may further reduce drag during launching operations. 
         [0077]    Referring now to  FIG. 6 , a flowchart of a flight vehicle deploying process  600 , according to an aspect of the present disclosure, is shown. 
         [0078]    Aircraft  102  may be utilized in a variety of ways and to achieve a variety of operational objectives. Aircraft may be used to deliver flight vehicle  106 , configured as an unmanned drone to a specified station altitude and area such that flight vehicle may carry out reconnaissance in an operational area. 
         [0079]    Process  600 , which utilizes aircraft  102 , a launching airstrip, launch rail or catapult and a recovery airstrip, begins at step  602  and immediately proceeds to step  604 . Process  600  encompasses a delivery flight path of launch vehicle  104 . Process  600  is suitable for delivering flight vehicle  106  to a release location and a release altitude where it may begin high-altitude, long-endurance flight operations. Such flight vehicle  106  may be optimized for high-altitude, long-endurance flight operations and unable to efficiently reach the release location and release altitude from takeoff without the aid of launch vehicle  104 . In another aspect, flight vehicle  106  is unable to takeoff in the separated configuration. 
         [0080]    In step  604 , aircraft  102  is launched from the launching airstrip or rail launcher. Aircraft  102  is configured to takeoff horizontally, therefore aircraft  102  may be launched from a runway or launcher designed for vehicles if the size and flight characteristics of aircraft  102 . For example, where aircraft  102  weighs the same as a Cessna® 150 (available from Cessna Aircraft Company of Wichita, Kans.) and requires a similar amount of runway distance to takeoff, aircraft  102  may be launched from civilian or government runways designed for Cessna  150  airplanes. Aircraft  102  takeoff may be assisted by assist motors  206 . In another aspect, takeoff is powered solely by launch vehicle  104  main engines. In another aspect, engine  202  and launch vehicle  104  main engines are engaged in order to facilitate takeoff. 
         [0081]    In step  606 , aircraft  102  is airborne and in the joined configuration. Aircraft  102  travels to a desired release location. The release location is an area where flight vehicle  106  will separate from launch vehicle  104 . The transit of step  606  may occur under the sole power of launch vehicle  104  main engines. 
         [0082]    In step  608 , Aircraft  102  has arrived at the release location and then travels to the release altitude. Release altitude is an altitude where flight vehicle  106  may operate. 
         [0083]    In step  610 , aircraft  102  transitions from the joined configuration to a separated configuration. After aircraft has arrived at the release location and altitude, connectors on flight vehicle  106  and launch vehicle  104  are actuated and flight vehicle  106  and launch vehicle  104  separate. Separation may be accomplished in a variety of ways. In an aspect, engine  202  remains inactive until connectors actuate. Then, engine  202  is activated and flight vehicle  106  maneuvers away from launch vehicle  104  under power. In another aspect, engine  202  activates prior to separation and may provide additional power for flight and separation of flight vehicle  106  and launch vehicle  104 . The wing portion of the flight vehicle  106  provides lift for the now separated flight vehicle  106 , enabling it to stay aloft. 
         [0084]    After separation, flight vehicle  106  may maneuver away and carry out its designed mission in an area of interest. In some aspects, after completing its mission, flight vehicle  106  flies back to a recovery airstrip. In other aspects, flight vehicle  106  is expendable and therefore does not return to a recovery airstrip. 
         [0085]    In step  612 , launch vehicle  104  is recovered. After separation, launch vehicle  104  may leave the release area, travel to a recovery airstrip, and land horizontally. Launch vehicle  104  may land at a runway or capture device configured to support aircraft of similar weight and landing requirements (e.g., runway length). 
         [0086]    In aspects where both launch vehicle  104  and flight vehicle  106  comprise engines, they may fly to and land at the same recovery airstrip. After landing, launch vehicle  104  and flight vehicle  106  or other compatible flight vehicle may be easily reconnected and re-equipped for another flight, enabling reusability while reducing processing time. 
         [0087]    Process  600  ends at step  614 . 
         [0088]    Referring now to  FIGS. 7 and 8 , perspective view of another configuration of aircraft  102 , in separated and joined configurations, respectively, according to aspects of the present disclosure, are shown. Variants may be short endurance or weapon capable. 
         [0089]    Multiple aspects of flight vehicle  106  may be utilized with a single launch vehicle  104  aspect. Launch vehicle  104  may be utilized with flight vehicles of  FIGS. 1-5  as well as flight vehicles of  FIGS. 7-12 . Flight vehicle  106  may be configured such that flight vehicle body  702  may carry larger payloads. In another aspect, flight vehicle  102  may be configured for orbital or suborbital trajectories.  FIGS. 7 and 8  reflect a configuration for an extremely small unmanned supersonic combat aircraft. They are area ruled to operate at supersonic speeds when joined, and the weapon stage contributes wing area which reduces the size of the carrier aircraft. The weapon stage could be configured to engage ground or air targets. By offering the smallest possible combat craft, cost and radar signature are reduced to enable swarm attacks against radar defenses. 
         [0090]    Referring now to  FIGS. 9-12 , perspective views of aircraft  102 , wherein aircraft  102  is configured to deploy flight vehicle  106  to space, according to aspects of the present disclosure, are shown. 
         [0091]    Flight vehicle  106  may be configured for operation in space. Flight vehicle  106  may be launched from launch vehicle  104  which may be configured to interface with other flight vehicles  104 , such as a high-altitude, long-endurance drone or missiles. 
         [0092]    Flight vehicle  106  may comprise enlarged elevons or rotatable wings  1002  (labeled, for clarity as rotatable wings  1002   a  and  1002   b  if  FIGS. 9-12 ). Rotatable wings  1002  allow the body geometry of flight vehicle  106  to be altered during operation, thereby facilitating maneuvers, aerobraking and the like. As shown in  FIG. 11 , rotatable wings  1002  may be positioned in an aero-braking orientation, increasing drag on flight vehicle  106 , thereby reducing velocity on reentry. Elevons may be hinged at an angle to impart yaw during roll for turns. 
         [0093]    While various aspects of the present disclosure have been described above, it should be understood that they have been presented by way of example and not limitation. It will be apparent to persons skilled in the relevant art(s) that various changes in form and detail can be made therein without departing from the spirit and scope of the present disclosure. Thus, the present disclosure should not be limited by any of the above described exemplary aspects, but should be defined only in accordance with the following claims and their equivalents. 
         [0094]    In addition, it should be understood that the figures in the attachments, which highlight the structure, methodology, functionality and advantages of the present disclosure, are presented for example purposes only. The present disclosure is sufficiently flexible and configurable, such that it may be implemented in ways other than that shown in the accompanying figures. As will be appreciated by those skilled in the relevant art(s) after reading the description herein, certain features from different aspects of the present disclosure may be combined to form yet new aspects of the present disclosure. 
         [0095]    Further, the purpose of the foregoing Abstract is to enable the U.S. Patent and Trademark Office and the public generally and especially the scientists, engineers and practitioners in the relevant art(s) who are not familiar with patent or legal terms or phraseology, to determine quickly from a cursory inspection the nature and essence of this technical disclosure. The Abstract is not intended to be limiting as to the scope of the present disclosure in any way.