Aircraft flight control surfaces are aerodynamic devices allowing a pilot to adjust and control the aircraft's flight attitude .
84-682: The North American X-15 is a hypersonic rocket-powered aircraft operated by the United States Air Force and the National Aeronautics and Space Administration (NASA) as part of the X-plane series of experimental aircraft . The X-15 set speed and altitude records in the 1960s, crossing the edge of outer space and returning with valuable data used in aircraft and spacecraft design. The X-15's highest speed, 4,520 miles per hour (7,274 km/h; 2,021 m/s),
168-525: A hypersonic speed is one that exceeds five times the speed of sound , often stated as starting at speeds of Mach 5 and above. The precise Mach number at which a craft can be said to be flying at hypersonic speed varies, since individual physical changes in the airflow (like molecular dissociation and ionization ) occur at different speeds; these effects collectively become important around Mach 5–10. The hypersonic regime can also be alternatively defined as speeds where specific heat capacity changes with
252-616: A tail in the shape of a V , and the moving parts at the back of those combine the functions of elevators and rudder. Delta wing aircraft may have " elevons " at the back of the wing, which combine the functions of elevators and ailerons. On low drag aircraft such as sailplanes , spoilers are used to disrupt airflow over the wing and greatly reduce lift. This allows a glider pilot to lose altitude without gaining excessive airspeed. Spoilers are sometimes called "lift dumpers". Spoilers that can be used asymmetrically are called spoilerons and can affect an aircraft's roll. Flaps are mounted on
336-527: A 1962 proposal, NASA considered using the B-52/X-15 as a launch platform for a Blue Scout rocket to place satellites weighing up to 150 pounds (68 kg) into orbit. In July and August 1963, pilot Joe Walker exceeded 100 km in altitude, joining NASA astronauts and Soviet cosmonauts as the first human beings to cross that line on their way to outer space . The USAF awarded astronaut wings to anyone achieving an altitude of 50 miles (80 km), while
420-459: A body's Mach number increases, the density behind a bow shock generated by the body also increases, which corresponds to a decrease in volume behind the shock due to conservation of mass . Consequently, the distance between the bow shock and the body decreases at higher Mach numbers. As Mach numbers increase, the entropy change across the shock also increases, which results in a strong entropy gradient and highly vortical flow that mixes with
504-515: A combined 13 flights which met the Air Force spaceflight criterion by exceeding the altitude of 50 miles (80 km), thus qualifying these pilots as being astronauts ; of those 13 flights, two (flown by the same civilian pilot) met the FAI definition (100 kilometres (62 mi)) of outer space . The 5 Air Force pilots qualified for military astronaut wings immediately, while
588-513: A feature called "Reaction Augmentation System" (RAS) that helped stabilize the vehicle at high altitude. The RAS was typically used for approximately three minutes of an X-15 flight before automatic power off. The alternative control setup used the MH-96 flight control system, which allowed one joystick in place of three and simplified pilot input. The MH-96 could automatically blend aerodynamic and rocket controls, depending on how effective each system
672-430: A given airspeed, level flight can only be maintained up to a certain given angle of bank. Beyond this angle of bank, the aircraft will suffer an accelerated stall if the pilot attempts to generate enough lift to maintain level flight. Some aircraft configurations have non-standard primary controls. For example, instead of elevators at the back of the stabilizers, the entire tailplane may change angle . Some aircraft have
756-494: A launch aircraft, drop, main engine start and acceleration, ballistic flight into thin air/space, re-entry into thicker air, unpowered glide to landing, and direct landing without a main-engine start. The main rocket engine operated only for a relatively short part of the flight but boosted the X-15 to its high speeds and altitudes. Without the main rocket engine thrust, the X-15's instruments and control surfaces remained functional, but
840-447: A nose-wheel carriage and two rear skids. The skids did not extend beyond the ventral fin , which required the pilot to jettison the lower fin just before landing. The lower fin was recovered by parachute. The X-15 was the product of developmental research, and changes were made to various systems over the course of the program and between the different models. The X-15 was operated under several different scenarios, including attachment to
924-521: A number of similarity parameters , which allow the simplification of a nearly infinite number of test cases into groups of similarity. For transonic and compressible flow , the Mach and Reynolds numbers alone allow good categorization of many flow cases. Hypersonic flows, however, require other similarity parameters. First, the analytic equations for the oblique shock angle become nearly independent of Mach number at high (~>10) Mach numbers. Second,
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#17327723158481008-419: A number of regimes. The selection of these regimes is rough, due to the blurring of the boundaries where a particular effect can be found. In this regime, the gas can be regarded as an ideal gas . Flow in this regime is still Mach number dependent. Simulations start to depend on the use of a constant-temperature wall, rather than the adiabatic wall typically used at lower speeds. The lower border of this region
1092-432: A pilot to balance the lift and drag being produced by the wings and control surfaces over a wide range of load and airspeed. This reduces the effort required to adjust or maintain a desired flight attitude . Elevator trim balances the control force necessary to maintain the correct aerodynamic force on the tail to balance the aircraft. Whilst carrying out certain flight exercises, a lot of trim could be required to maintain
1176-428: A problem of wing warping and are easier to build into structures. An aircraft is free to rotate around three axes that are perpendicular to each other and intersect at its center of gravity (CG). To control position and direction a pilot must be able to control rotation about each of them. The transverse axis , also known as lateral axis , passes through an aircraft from wingtip to wingtip. Rotation about this axis
1260-402: A short period of time and the aircraft will return to its level flight trimmed airspeed. Except for very light aircraft, trim tabs on the elevators are unable to provide the force and range of motion desired. To provide the appropriate trim force the entire horizontal tail plane is made adjustable in pitch. This allows the pilot to select exactly the right amount of positive or negative lift from
1344-579: A similarity parameter, similar to the Whitcomb area rule , which allowed similar configurations to be compared. In the study of hypersonic flow over slender bodies, the product of the freestream Mach number M ∞ {\displaystyle M_{\infty }} and the flow deflection angle θ {\displaystyle \theta } , known as the hypersonic similarity parameter: K = M ∞ θ {\displaystyle K=M_{\infty }\theta }
1428-558: A traditional center stick between a left 3-axis joystick that sent commands to the Reaction Control System, and a third joystick on the right used during high-G maneuvers to augment the center stick. In addition to pilot input, the X-15 " Stability Augmentation System " (SAS) sent inputs to the aerodynamic controls to help the pilot maintain attitude control . The Reaction Control System (RCS) could be operated in two modes – manual and automatic. The automatic mode used
1512-400: A trimming control surface on the elevator , but larger aircraft also have a trim control for the rudder, and another for the ailerons. The rudder trim is to counter any asymmetric thrust from the engines. Aileron trim is to counter the effects of the centre of gravity being displaced from the aircraft centerline. This can be caused by fuel or an item of payload being loaded more on one side of
1596-555: Is around Mach 5, where ramjets become inefficient, and the upper border around Mach 10–12. This is a subset of the perfect gas regime, where the gas can be considered chemically perfect, but the rotational and vibrational temperatures of the gas must be considered separately, leading to two temperature models. See particularly the modeling of supersonic nozzles, where vibrational freezing becomes important. In this regime, diatomic or polyatomic gases (the gases found in most atmospheres) begin to dissociate as they come into contact with
1680-412: Is called pitch . Pitch changes the vertical direction that the aircraft's nose is pointing. The elevators are the primary control surfaces for pitch. The longitudinal axis passes through the aircraft from nose to tail. Rotation about this axis is called roll . The angular displacement about this axis is called bank. The pilot changes bank angle by increasing the lift on one wing and decreasing it on
1764-491: Is called the transonic range. Aircraft designed to fly at supersonic speeds show large differences in their aerodynamic design because of the radical differences in the behavior of flows above Mach 1. Sharp edges, thin aerofoil -sections, and all-moving tailplane / canards are common. Modern combat aircraft must compromise in order to maintain low-speed handling; "true" supersonic designs, generally incorporating delta wings, are rarer. The categorization of airflow relies on
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#17327723158481848-449: Is considered to be an important governing parameter. The slenderness ratio of a vehicle τ = d / l {\displaystyle \tau =d/l} , where d {\displaystyle d} is the diameter and l {\displaystyle l} is the length, is often substituted for θ {\displaystyle \theta } . Hypersonic flow can be approximately separated into
1932-420: Is for this reason that an MD-80 tail looks like it has a 'split' elevator system. In the canard arrangement , the elevators are hinged to the rear of a foreplane and move in the opposite sense, for example when the pilot pulls the stick back the elevators go down to increase the lift at the front and lift the nose up. The rudder is typically mounted on the trailing edge of the vertical stabilizer , part of
2016-431: Is less than Mach 1. The critical Mach number (Mcrit) is lowest free stream Mach number at which airflow over any part of the aircraft first reaches Mach 1. So the subsonic speed range includes all speeds that are less than Mcrit. The transonic speed range is that range of speeds within which the airflow over different parts of an aircraft is between subsonic and supersonic. So the regime of flight from Mcrit up to Mach 1.3
2100-616: The FAI set the limit of space at 100 kilometers (62.1 mi). On 15 November 1967, U.S. Air Force test pilot Major Michael J. Adams was killed during X-15 Flight 191 when X-15-3, AF Ser. No. 56-6672 , entered a hypersonic spin while descending, then oscillated violently as aerodynamic forces increased after re-entry. As his aircraft's flight control system operated the control surfaces to their limits, acceleration built to 15 g 0 (150 m/s ) vertical and 8.0 g 0 (78 m/s ) lateral. The airframe broke apart at 60,000 feet (18 km) altitude, scattering
2184-515: The XLR99 rocket engine, generating 57,000 pounds-force (250 kN) of thrust. The remaining 175 flights of the X-15 used XLR99 engines, in a single engine configuration. The XLR99 used anhydrous ammonia and liquid oxygen as propellant, and hydrogen peroxide to drive the high-speed turbopump that delivered propellants to the engine. It could burn 15,000 pounds (6,804 kg) of propellant in 80 seconds; Jules Bergman titled his book on
2268-425: The boundary layer . A portion of the large kinetic energy associated with flow at high Mach numbers transforms into internal energy in the fluid due to viscous effects. The increase in internal energy is realized as an increase in temperature. Since the pressure gradient normal to the flow within a boundary layer is approximately zero for low to moderate hypersonic Mach numbers, the increase of temperature through
2352-447: The bow shock generated by the body. Surface catalysis plays a role in the calculation of surface heating, meaning that the type of surface material also has an effect on the flow. The lower border of this regime is where any component of a gas mixture first begins to dissociate in the stagnation point of a flow (which for nitrogen is around 2000 K). At the upper border of this regime, the effects of ionization start to have an effect on
2436-415: The empennage . When the pilot pushes the left pedal, the rudder deflects left. Pushing the right pedal causes the rudder to deflect right. Deflecting the rudder right pushes the tail left and causes the nose to yaw to the right. Centering the rudder pedals returns the rudder to neutral and stops the yaw. The ailerons primarily cause roll. Whenever lift is increased, induced drag is also increased so when
2520-599: The rocket engine . The X-15 was built by two manufacturers: North American Aviation was contracted for the airframe in November 1955, and Reaction Motors was contracted for building the engines in 1956. Like many X-series aircraft, the X-15 was designed to be carried aloft and drop launched from under the wing of a B-52 mother ship . Air Force NB-52A, "The High and Mighty One" (serial 52-0003), and NB-52B, "The Challenger" (serial 52-0008, also known as Balls 8 ) served as carrier planes for all X-15 flights. Release of
2604-596: The space border . All five Air Force pilots flew above 50 miles and were awarded military astronaut wings contemporaneously with their achievements, including Adams, who received the distinction posthumously following the flight 191 disaster . However the other three were NASA employees and did not receive a comparable decoration at the time. In 2004, the Federal Aviation Administration conferred its first-ever commercial astronaut wings on Mike Melvill and Brian Binnie , pilots of
North American X-15 - Misplaced Pages Continue
2688-497: The 3 civilian pilots were eventually awarded NASA astronaut wings in 2005, 35 years after the last X-15 flight. The X-15 was based on a concept study from Walter Dornberger for the National Advisory Committee for Aeronautics (NACA) of a hypersonic research aircraft. The requests for proposal (RFPs) were published on 30 December 1954 for the airframe and on 4 February 1955 for
2772-618: The Smithsonian Air & Space Museum for display. Both surviving X-15s are currently on display at museums in the United States. In addition, three mockups and both B-52 Stratofortresses used as motherships are on display as well. During 13 of the 199 total X-15 flights, eight pilots flew above 264,000 feet (50.0 mi; 80 km), thereby qualifying as astronauts according to the US Armed Forces definition of
2856-443: The X-15 from NB-52A took place at an altitude of about 8.5 miles (13.7 km) (45,000 feet) and a speed of about 500 miles per hour (805 km/h). The X-15 fuselage was long and cylindrical, with rear fairings that flattened its appearance, and thick, dorsal and ventral wedge-fin stabilizers. Parts of the fuselage (the outer skin) were heat-resistant nickel alloy ( Inconel -X 750). The retractable landing gear comprised
2940-521: The X-15's wreckage across 50 square miles (130 km). On 8 May 2004, a monument was erected at the cockpit's locale, near Johannesburg, California . Major Adams was posthumously awarded Air Force astronaut wings for his final flight in X-15-3, which had reached an altitude of 50.4 miles (81.1 km). In 1991, his name was added to the Astronaut Memorial . The second plane, X-15-2,
3024-406: The aileron control is moved to roll the aircraft to the left, the right aileron is lowered which increases lift on the right wing and therefore increases induced drag on the right wing. Using ailerons causes adverse yaw , meaning the nose of the aircraft yaws in a direction opposite to the aileron application. When moving the aileron control to bank the wings to the left, adverse yaw moves the nose of
3108-411: The aircraft could not maintain altitude. As the X-15 also had to be controlled in an environment where there was too little air for aerodynamic flight control surfaces , it had a reaction control system (RCS) that used rocket thrusters. There were two different X-15 pilot control setups: one used three joysticks, the other, one joystick. The X-15 type with multiple control sticks for the pilot placed
3192-408: The aircraft descending if not countered. To maintain level flight requires increased positive (up) elevator to increase the angle of attack, increase the total lift generated and keep the vertical component of lift equal with the weight of the aircraft. This cannot continue indefinitely. The total load factor required to maintain level flight is directly related to the bank angle . This means that for
3276-433: The aircraft to the right . Adverse yaw is most pronounced in low-speed aircraft with long wings, such as gliders. It is counteracted by the pilot using the rudder pedals. Differential ailerons are ailerons which have been rigged such that the downgoing aileron deflects less than the upward-moving one, causing less adverse yaw. The rudder is a fundamental control surface which is typically controlled by pedals rather than at
3360-418: The airframe on hinges or tracks so they may move and thus deflect the air stream passing over them. This redirection of the air stream generates an unbalanced force to rotate the plane about the associated axis. Ailerons are mounted on the trailing edge of each wing near the wingtips and move in opposite directions. When the pilot moves the aileron control to the left, or turns the wheel counter-clockwise,
3444-452: The airstream. Some designs feature separate anti-flutter weights. (In radio controlled model aircraft, the term "control horn" has a different meaning) In the simplest arrangement, trimming is done by a mechanical spring (or bungee ) which adds appropriate force to augment the pilot's control input. The spring is usually connected to an elevator trim lever to allow the pilot to set the spring force applied. Most fixed-wing aircraft have
North American X-15 - Misplaced Pages Continue
3528-413: The bank angle to zero to fly straight. The elevator is a moveable part of the horizontal stabilizer , hinged to the back of the fixed part of the horizontal tail. The elevators move up and down together. When the pilot pulls the stick backward, the elevators go up. Pushing the stick forward causes the elevators to go down. Raised elevators push down on the tail and cause the nose to pitch up. This makes
3612-559: The basic principles remain. The controls (stick and rudder ) for rotary wing aircraft ( helicopter or autogyro ) accomplish the same motions about the three axes of rotation , but manipulate the rotating flight controls ( main rotor disk and tail rotor disk) in a completely different manner. Flight control surfaces are operated by aircraft flight control systems . Considered as a generalized fluid control surface, rudders, in particular, are shared between aircraft and watercraft . The Wright brothers are credited with developing
3696-432: The blunt end at the rear of the X-15 could produce as much drag as an entire F-104 Starfighter . A wedge shape was used because it is more effective than the conventional tail as a stabilizing surface at hypersonic speeds. A vertical-tail area equal to 60 percent of the wing area was required to give the X-15 adequate directional stability. Stability at hypersonic speeds was aided by side panels that could be extended from
3780-562: The boundary layer coincides with a decrease in density. This causes the bottom of the boundary layer to expand, so that the boundary layer over the body grows thicker and can often merge with the shock wave near the body leading edge. High temperatures due to a manifestation of viscous dissipation cause non-equilibrium chemical flow properties such as vibrational excitation and dissociation and ionization of molecules resulting in convective and radiative heat-flux . Although "subsonic" and "supersonic" usually refer to speeds below and above
3864-399: The commercial SpaceShipOne , another spaceplane with a flight profile comparable to the X-15's. Following this in 2005, NASA retroactively awarded its civilian astronaut wings to Dana (then living), and to McKay and Walker (posthumously). Forrest S. Petersen, the only Navy pilot in the X-15 program, never took the aircraft above the requisite altitude and thus never earned astronaut wings. Of
3948-493: The desired angle of attack. This mainly applies to slow flight , where a nose-up attitude is required, in turn requiring a lot of trim causing the tailplane to exert a strong downforce. Elevator trim is correlated with the speed of the airflow over the tail, thus airspeed changes to the aircraft require re-trimming. An important design parameter for aircraft is the stability of the aircraft when trimmed for level flight. Any disturbances such as gusts or turbulence will be damped over
4032-407: The direction of yaw. This arises initially from the increased speed of the wing opposite to the direction of yaw and the reduced speed of the other wing. The faster wing generates more lift and so rises, while the other wing tends to go down because of generating less lift. Continued application of rudder sustains rolling tendency because the aircraft flying at an angle to the airflow - skidding towards
4116-523: The first practical control surfaces. It is a main part of their patent on flying. Unlike modern control surfaces, they used wing warping . In an attempt to circumvent the Wright patent , Glenn Curtiss made hinged control surfaces, the same type of concept first patented some four decades earlier in the United Kingdom . Hinged control surfaces have the advantage of not causing stresses that are
4200-482: The first time on 25 June 1964. It reached its maximum speed of 4,520 miles per hour (7,274 km/h) in October 1967 with pilot William "Pete" Knight of the U.S. Air Force in control. Five principal aircraft were used during the X-15 program: three X-15 planes and two modified "nonstandard" NB-52 bombers: Additionally, F-100 , F-104 and F5D chase aircraft and C-130 and C-47 transports supported
4284-899: The flaps are deployed, thus acting as both a flap and a roll-control inboard aileron. Slats , also known as leading edge devices , are extensions to the front of a wing for lift augmentation, and are intended to reduce the stalling speed by altering the airflow over the wing. Slats may be fixed or retractable - fixed slats (e.g. as on the Fieseler Fi 156 Storch ) give excellent slow speed and STOL capabilities, but compromise higher speed performance. Retractable slats, as seen on most airliners, provide reduced stalling speed for take-off and landing, but are retracted for cruising. Air brakes are used to increase drag. Spoilers might act as air brakes, but are not pure air brakes as they also function as lift-dumpers or in some cases as roll control surfaces. Air brakes are usually surfaces that deflect outwards from
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#17327723158484368-420: The flow. In this regime the ionized electron population of the stagnated flow becomes significant, and the electrons must be modeled separately. Often the electron temperature is handled separately from the temperature of the remaining gas components. This region occurs for freestream flow velocities around 3–4 km/s. Gases in this region are modeled as non-radiating plasmas . Above around 12 km/s,
4452-508: The formation of strong shocks around aerodynamic bodies means that the freestream Reynolds number is less useful as an estimate of the behavior of the boundary layer over a body (although it is still important). Finally, the increased temperature of hypersonic flow mean that real gas effects become important. Research in hypersonics is therefore often called aerothermodynamics , rather than aerodynamics . The introduction of real gas effects means that more variables are required to describe
4536-410: The forward wing. When applying right rudder in an aircraft with dihedral the left hand wing will have increased angle of attack and the right hand wing will have decreased angle of attack which will result in a roll to the right. An aircraft with anhedral will show the opposite effect. This effect of the rudder is commonly used in model aircraft where if sufficient dihedral or polyhedral is included in
4620-479: The full state of a gas. Whereas a stationary gas can be described by three variables ( pressure , temperature , adiabatic index ), and a moving gas by four ( flow velocity ), a hot gas in chemical equilibrium also requires state equations for the chemical components of the gas, and a gas in nonequilibrium solves those state equations using time as an extra variable. This means that for nonequilibrium flow, something between 10 and 100 variables may be required to describe
4704-508: The fuselage (in most cases symmetrically on opposing sides) into the airstream in order to increase form-drag. As they are in most cases located elsewhere on the aircraft, they do not directly affect the lift generated by the wing. Their purpose is to slow down the aircraft. They are particularly useful when a high rate of descent is required. They are common on high performance military aircraft as well as civilian aircraft, especially those lacking reverse thrust capability. Trimming controls allow
4788-490: The heat transfer to a vehicle changes from being conductively dominated to radiatively dominated. The modeling of gases in this regime is split into two classes: The modeling of optically thick gases is extremely difficult, since, due to the calculation of the radiation at each point, the computation load theoretically expands exponentially as the number of points considered increases. Flight control surface Development of an effective set of flight control surfaces
4872-480: The left aileron goes up and the right aileron goes down. A raised aileron reduces lift on that wing and a lowered one increases lift, so moving the aileron control in this way causes the left wing to drop and the right wing to rise. This causes the aircraft to roll to the left and begin to turn to the left. Centering the control returns the ailerons to the neutral position, maintaining the bank angle . The aircraft will continue to turn until opposite aileron motion returns
4956-413: The lift force, which is perpendicular to the wings, in the direction of the intended turn by rolling the aircraft into the turn. As the bank angle is increased, the lifting force can be split into two components: one acting vertically and one acting horizontally. If the total lift is kept constant, the vertical component of lift will decrease. As the weight of the aircraft is unchanged, this would result in
5040-595: The local speed of sound respectively, aerodynamicists often use these terms to refer to particular ranges of Mach values. When an aircraft approaches transonic speeds (around Mach 1), it enters a special regime. The usual approximations based on the Navier–Stokes equations , which work well for subsonic designs, start to break down because, even in the freestream, some parts of the flow locally exceed Mach 1. So, more sophisticated methods are needed to handle this complex behavior. The "supersonic regime" usually refers to
5124-400: The main engines and auxiliary power units (APUs). Additional tanks for helium and liquid nitrogen performed other functions; the fuselage interior was purged with helium gas, and liquid nitrogen was used as coolant for various systems. The X-15 had a thick wedge tail to enable it to fly in a steady manner at hypersonic speeds. This produced a significant amount of base drag at lower speeds;
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#17327723158485208-400: The other. This differential lift causes rotation around the longitudinal axis. The ailerons are the primary control of bank. The rudder also has a secondary effect on bank. The vertical axis passes through an aircraft from top to bottom. Rotation about this axis is called yaw . Yaw changes the direction the aircraft's nose is pointing, left or right. The primary control of yaw is with
5292-420: The previously-operated Space Shuttle ; various reusable spacecraft in development such as SpaceX Starship and Rocket Lab Electron ; and (theoretical) spaceplanes . In the following table, the "regimes" or "ranges of Mach values" are referenced instead of the usual meanings of "subsonic" and "supersonic". The subsonic speed range is that range of speeds within which, all of the airflow over an aircraft
5376-405: The program Ninety Seconds to Space to describe the total powered flight time of the aircraft. The X-15 reaction control system (RCS), for maneuvering in the low-pressure/density environment, used high-test peroxide (HTP), which decomposes into water and oxygen in the presence of a catalyst and could provide a specific impulse of 140 s (1.4 km/s). The HTP also fueled a turbopump for
5460-457: The program. The 200th flight over Nevada was first scheduled for 21 November 1968, to be flown by William "Pete" Knight. Numerous technical problems and outbreaks of bad weather delayed this proposed flight six times, and it was permanently canceled on 20 December 1968. This X-15 (56-6670) was detached from the B-52 and then put into indefinite storage. The aircraft was later donated to
5544-401: The rudder. Ailerons also have a secondary effect on yaw. These axes move with the aircraft and change relative to the earth as the aircraft moves. For example, for an aircraft whose left wing is pointing straight down, its "vertical" axis is parallel with the ground, while its "transverse" axis is perpendicular to the ground. The main control surfaces of a fixed-wing aircraft are attached to
5628-455: The set of Mach numbers for which linearised theory may be used; for example, where the ( air ) flow is not chemically reacting and where heat transfer between air and vehicle may be reasonably neglected in calculations. Generally, NASA defines "high" hypersonic as any Mach number from 10 to 25, and re-entry speeds as anything greater than Mach 25. Among the spacecraft operating in these regimes are returning Soyuz and Dragon space capsules ;
5712-437: The state of the gas at any given time. Additionally, rarefied hypersonic flows (usually defined as those with a Knudsen number above 0.1) do not follow the Navier–Stokes equations . Hypersonic flows are typically categorized by their total energy, expressed as total enthalpy (MJ/kg), total pressure (kPa-MPa), stagnation pressure (kPa-MPa), stagnation temperature (K), or flow velocity (km/s). Wallace D. Hayes developed
5796-420: The stick. It is the primary means of controlling yaw—the rotation of an airplane about its vertical axis. The rudder may also be called upon to counter-act the adverse yaw produced by the roll-control surfaces. If rudder is continuously applied in level flight the aircraft will yaw initially in the direction of the applied rudder – the primary effect of rudder. After a few seconds the aircraft will tend to bank in
5880-400: The tail plane while reducing drag from the elevators. A control horn is a section of control surface which projects ahead of the pivot point. It generates a force which tends to increase the surface's deflection thus reducing the control pressure experienced by the pilot. Control horns may also incorporate a counterweight which helps to balance the control and prevent it from fluttering in
5964-600: The tail to increase the overall surface area, and these panels doubled as air brakes. Before 1958, United States Air Force (USAF) and NACA officials discussed an orbital X-15 spaceplane , the X-15B that would launch into outer space from atop an SM-64 Navaho missile. This was canceled when the NACA became NASA and adopted Project Mercury instead. By 1959, the Boeing X-20 Dyna-Soar space-glider program
6048-470: The temperature of the flow as kinetic energy of the moving object is converted into heat. While the definition of hypersonic flow can be quite vague and is generally debatable (especially due to the absence of discontinuity between supersonic and hypersonic flows), a hypersonic flow may be characterized by certain physical phenomena that can no longer be analytically discounted as in supersonic flow. The peculiarities in hypersonic flows are as follows: As
6132-752: The thirteen flights, only two – flights 90 and 91, piloted by Walker – exceeded the 100 km (62 mi) altitude used by the FAI to denote the Kármán line . fatal Killed in the crash of X-15-3 Died in a group formation accident on June 8, 1966. Other configurations include the Reaction Motors XLR11 equipped X-15, and the long version. Data from General characteristics Performance Aircraft of comparable role, configuration, and era Related lists Hypersonic speed In aerodynamics ,
6216-541: The trailing edge on the inboard section of each wing (near the wing roots). They are deflected down to increase the effective curvature of the wing. Flaps raise the maximum lift coefficient of the aircraft and therefore reduce its stalling speed. They are used during low speed, high angle of attack flight including take-off and descent for landing. Some aircraft are equipped with " flaperons ", which are more commonly called "inboard ailerons" . These devices function primarily as ailerons, but on some aircraft, will "droop" when
6300-418: The wing design, primary roll control such as ailerons may be omitted altogether. Unlike turning a boat, changing the direction of an aircraft normally must be done with the ailerons rather than the rudder. The rudder turns (yaws) the aircraft but has little effect on its direction of travel. With aircraft, the change in direction is caused by the horizontal component of lift, acting on the wings. The pilot tilts
6384-424: The wings fly at a higher angle of attack , which generates more lift and more drag . Centering the stick returns the elevators to neutral and stops the change of pitch. Some aircraft, such as an MD-80 , use a servo tab within the elevator surface to aerodynamically move the main surface into position. The direction of travel of the control tab will thus be in a direction opposite to the main control surface. It
6468-518: Was a critical advance in the development of aircraft. Early efforts at fixed-wing aircraft design succeeded in generating sufficient lift to get the aircraft off the ground, but once aloft, the aircraft proved uncontrollable, often with disastrous results. The development of effective flight controls is what allowed stable flight. This article describes the control surfaces used on a fixed-wing aircraft of conventional design. Other fixed-wing aircraft configurations may use different control surfaces but
6552-400: Was achieved on 3 October 1967, when William J. Knight flew at Mach 6.7 at an altitude of 102,100 feet (31,120 m), or 19.34 miles. This set the official world record for the highest speed ever recorded by a crewed, powered aircraft, which remains unbroken. During the X-15 program, 12 pilots flew a combined 199 flights. Of these, 8 pilots flew
6636-549: Was an unpowered glide flight by Scott Crossfield , on 8 June 1959. Crossfield also piloted the first powered flight on 17 September 1959, and his first flight with the XLR-99 rocket engine on 15 November 1960. Twelve test pilots flew the X-15. Among these were Neil Armstrong , later a NASA astronaut and the first man to set foot on the Moon, and Joe Engle , later a commander of NASA Space Shuttle missions. In
6720-450: Was at controlling the aircraft. Among the many controls were the rocket engine throttle and a control for jettisoning the ventral tail fin. Other features of the cockpit included heated windows to prevent icing and a forward headrest for periods of high deceleration. The X-15 had an ejection seat designed to operate at speeds up to Mach 4 (4,500 km/h; 2,800 mph) and/or 120,000 feet (37 km) (23 miles) altitude, although it
6804-532: Was fed separately to the pilot. The initial 24 powered flights used two Reaction Motors XLR11 liquid-propellant rocket engines, enhanced to provide a total of 16,000 pounds-force (71 kN) of thrust as compared to the 6,000 pounds-force (27 kN) that a single XLR11 provided in 1947 to make the Bell X-1 the first aircraft to fly faster than the speed of sound . The XLR11 used ethyl alcohol and liquid oxygen . By November 1960, Reaction Motors delivered
6888-427: Was never used during the program. In the event of ejection, the seat was designed to deploy fins, which were used until it reached a safer speed/altitude at which to deploy its main parachute. Pilots wore pressure suits, which could be pressurized with nitrogen gas. Above 35,000 feet (11 km) altitude, the cockpit was pressurized to 3.5 psi (24 kPa; 0.24 atm) with nitrogen gas, while oxygen for breathing
6972-421: Was rebuilt after a landing accident on 9 November 1962 which damaged the craft and injured its pilot, John McKay . The new plane renamed X-15A-2 , had a new 28 -in. fuselage extension to carry liquid hydrogen. It was lengthened by 2.4 feet (73 cm), had a pair of auxiliary fuel tanks attached beneath its fuselage and wings, and a complete heat-resistant ablative coating was added. It took flight for
7056-507: Was to become the USAF's preferred means for launching military crewed spacecraft into orbit. This program was canceled in the early 1960s before an operational vehicle could be built. Various configurations of the Navaho were considered, and another proposal involved a Titan I stage. Three X-15s were built, flying 199 test flights, the last on 24 October 1968. The first X-15 flight
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