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136-533: At the time of the ASR-9 installment, the system was a significant improvement over the S-band ASR radars being used by airports. The radar system was designed to meet, or exceed the need of a terminal Air Traffic Control Automation facility through the year 2005. The ASR-9 utilized a dual beam antenna, a dual channel antenna, a linear-wide range receiver and new digital processing equipment. The processor installed on

272-466: A "prior experience" bid, where anyone with an FAA Control Tower Operator certificate (CTO) and 52 weeks of experience could apply. This was a revolving bid, every month the applicants on this bid were sorted out, and eligible applicants were hired and sent directly to facilities, bypassing the FAA academy entirely. In the process of promoting diversity, the FAA revised its hiring process. The FAA later issued

408-545: A 19-species model. An important aspect of modelling non-equilibrium real gas effects is radiative heat flux. If a vehicle is entering an atmosphere at very high speed (hyperbolic trajectory, lunar return) and has a large nose radius then radiative heat flux can dominate TPS heating. Radiative heat flux during entry into an air or carbon dioxide atmosphere typically comes from asymmetric diatomic molecules; e.g., cyanogen (CN), carbon monoxide , nitric oxide (NO), single ionized molecular nitrogen etc. These molecules are formed by

544-536: A CTI certificate allowed a prospective controller to skip the Air Traffic Basics part of the academy, about a 30- to 45-day course, and go right into Initial Qualification Training (IQT). All prospective controllers, CTI or not, have had to pass the FAA Academy in order to be hired as a controller. Failure at the academy means FAA employment is terminated. In January 2015 they launched another pipeline,

680-471: A Gibbs free energy equilibrium program, the iterative process from the originally specified molecular composition to the final calculated equilibrium composition is essentially random and not time accurate. With a non-equilibrium program, the computation process is time accurate and follows a solution path dictated by chemical and reaction rate formulas. The five species model has 17 chemical formulas (34 when counting reverse formulas). The Lighthill-Freeman model

816-636: A Special Agent with the Office of Inspector General for the Department of Transportation and with FAA Security, is one of the most outspoken critics of FAA. Rather than commend the agency for proposing a $ 10.2 million fine against Southwest Airlines for its failure to conduct mandatory inspections in 2008, he was quoted as saying the following in an Associated Press story: "Penalties against airlines that violate FAA directives should be stiffer. At $ 25,000 per violation, Gutheinz said, airlines can justify rolling

952-499: A challenge. The experimental measurement of radiative heat flux (typically done with shock tubes) along with theoretical calculation through the unsteady Schrödinger equation are among the more esoteric aspects of aerospace engineering. Most of the aerospace research work related to understanding radiative heat flux was done in the 1960s, but largely discontinued after conclusion of the Apollo Program. Radiative heat flux in air

1088-519: A college that offered a CTI program. Before the change, candidates who had completed coursework at participating colleges and universities could be "fast-tracked" for consideration. However, the CTI program had no guarantee of a job offer, nor was the goal of the program to teach people to work actual traffic. The goal of the program was to prepare people for the FAA Academy in Oklahoma City, OK. Having

1224-459: A complete sphere or a spherical section forebody with a converging conical afterbody. The aerodynamics of a sphere or spherical section are easy to model analytically using Newtonian impact theory. Likewise, the spherical section's heat flux can be accurately modeled with the Fay–Riddell equation . The static stability of a spherical section is assured if the vehicle's center of mass is upstream from

1360-435: A converging conical afterbody. It flew a lifting entry with a hypersonic trim angle of attack of −27° (0° is blunt-end first) to yield an average L/D (lift-to-drag ratio) of 0.368. The resultant lift achieved a measure of cross-range control by offsetting the vehicle's center of mass from its axis of symmetry, allowing the lift force to be directed left or right by rolling the capsule on its longitudinal axis . Other examples of

1496-421: A few government facilities", and that humanity would never get to Mars under those rules. A Designated Engineering Representative (DER) is an engineer who is appointed under 14 CFR section 183.29 to act on behalf of a company or as an independent consultant (IC). The DER system enables the FAA to delegate certain involvement in airworthiness exams, tests, and inspections to qualified technical people outside of

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1632-483: A flight instructor (Gold Seal certification), a 50-year aviator (Wright Brothers Master Pilot Award), a 50-year mechanic (Charles Taylor Master Mechanic Award) or as a proficient pilot. The latter, the FAA " WINGS Program ", provides a lifetime series of grouped proficiency activities at three levels (Basic, Advanced, and Master) for pilots who have undergone several hours of ground and flight training since their last WINGS award, or "Phase". The FAA encourages volunteerism in

1768-429: A four-year degree or five years of full-time work experience to apply, rather than the closed college program or Veterans Recruitment Appointment bids, something that had last been done in 2008. Thousands were hired, including veterans, Collegiate Training Initiative graduates, and people who are true "off the street" hires. The move was made to open the job up to more people who might make good controllers but did not go to

1904-455: A gas in equilibrium with fixed pressure and temperature can be determined through the Gibbs free energy method . Gibbs free energy is simply the total enthalpy of the gas minus its total entropy times temperature. A chemical equilibrium program normally does not require chemical formulas or reaction-rate equations. The program works by preserving the original elemental abundances specified for

2040-572: A gas that are important to aeronautical engineers who design heat shields: Almost all aeronautical engineers are taught the perfect (ideal) gas model during their undergraduate education. Most of the important perfect gas equations along with their corresponding tables and graphs are shown in NACA Report 1135. Excerpts from NACA Report 1135 often appear in the appendices of thermodynamics textbooks and are familiar to most aeronautical engineers who design supersonic aircraft. The perfect gas theory

2176-574: A heat shield designer must use a real gas model . An entry vehicle's pitching moment can be significantly influenced by real-gas effects. Both the Apollo command module and the Space Shuttle were designed using incorrect pitching moments determined through inaccurate real-gas modelling. The Apollo-CM's trim-angle angle of attack was higher than originally estimated, resulting in a narrower lunar return entry corridor. The actual aerodynamic center of

2312-656: A mock-up of the ablative material to be analyzed within a hypersonic wind tunnel. Testing of ablative materials occurs at the Ames Arc Jet Complex. Many spacecraft thermal protection systems have been tested in this facility, including the Apollo, space shuttle, and Orion heat shield materials. Carbon phenolic was originally developed as a rocket nozzle throat material (used in the Space Shuttle Solid Rocket Booster ) and for reentry-vehicle nose tips. The thermal conductivity of

2448-405: A moving target with circular polarization, therefore significantly enhancing the ability to locate aircraft in various weather conditions. In addition to the enhanced detection system, six separate weather channels can be switched on to display the precipitation reflectivity measured from the vertical elevation beam. The measurements taken by the weather system are updated every 30 seconds to increase

2584-425: A new airport aid program and certain added responsibilities for airport safety. During the 1960s and 1970s, the FAA also started to regulate high altitude (over 500 feet) kite and balloon flying. By the mid-1970s, the agency had achieved a semi-automated air traffic control system using both radar and computer technology. This system required enhancement to keep pace with air traffic growth, however, especially after

2720-706: A new independent agency, the Civil Aeronautics Authority . The legislation also expanded the government's role by giving the CAA the authority and the power to regulate airline fares and to determine the routes that air carriers would serve. President Franklin D. Roosevelt split the authority into two agencies in 1940: the Civil Aeronautics Administration (CAA) and the Civil Aeronautics Board (CAB). CAA

2856-454: A nose radius of 1 meter, i.e., time of travel is about 18 microseconds. This is roughly the time required for shock-wave-initiated chemical dissociation to approach chemical equilibrium in a shock layer for a 7.8 km/s entry into air during peak heat flux. Consequently, as air approaches the entry vehicle's stagnation point, the air effectively reaches chemical equilibrium thus enabling an equilibrium model to be usable. For this case, most of

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2992-402: A nose radius of 2.34 cm, a forward-frustum half-angle of 10.4°, an inter-frustum radius of 14.6 cm, aft-frustum half-angle of 6°, and an axial length of 2.079 meters. No accurate diagram or picture of AMaRV has ever appeared in the open literature. However, a schematic sketch of an AMaRV-like vehicle along with trajectory plots showing hairpin turns has been published. AMaRV's attitude

3128-461: A particular TPS material is usually proportional to the material's density. Carbon phenolic is a very effective ablative material, but also has high density which is undesirable. The NASA Galileo Probe used carbon phenolic for its TPS material. If the heat flux experienced by an entry vehicle is insufficient to cause pyrolysis then the TPS material's conductivity could allow heat flux conduction into

3264-421: A perfect gas model, the ratio of specific heats (also called isentropic exponent , adiabatic index , gamma , or kappa ) is assumed to be constant along with the gas constant . For a real gas, the ratio of specific heats can wildly oscillate as a function of temperature. Under a perfect gas model there is an elegant set of equations for determining thermodynamic state along a constant entropy stream line called

3400-425: A report that the "bio-data" was not a reliable test for future performance. However, the "Bio-Q" was not the determining factor for hiring, it was merely a screening tool to determine who would take a revised Air Traffic Standardized Aptitude Test (ATSAT). Due to cost and time, it was not practical to give all 30,000 some applicants the revised ATSAT, which has since been validated. In 2015 Fox News levied criticism that

3536-670: A series of midair collisions—most notably the 1956 Grand Canyon mid-air collision ) prompted passage of the Federal Aviation Act of 1958 . This legislation passed the CAA's functions to a new independent body, the Federal Aviation Agency. The act also transferred air safety regulation from the CAB to the FAA, and gave it sole responsibility for a joint civil-military system of air navigation and air traffic control. The FAA's first administrator, Elwood R. Quesada ,

3672-404: A spacecraft capable of being navigated or following a predetermined course. Technologies and procedures allowing the controlled atmospheric entry, descent, and landing of spacecraft are collectively termed as EDL . Objects entering an atmosphere experience atmospheric drag , which puts mechanical stress on the object, and aerodynamic heating —caused mostly by compression of the air in front of

3808-428: A specific destination on the surface at zero velocity while keeping stresses on the spacecraft and any passengers within acceptable limits. This may be accomplished by propulsive or aerodynamic (vehicle characteristics or parachute ) means, or by some combination. There are several basic shapes used in designing entry vehicles: The simplest axisymmetric shape is the sphere or spherical section. This can either be

3944-407: A sphere-cone shape and were the first American example of a non-munition entry vehicle ( Discoverer-I , launched on 28 February 1959). The sphere-cone was later used for space exploration missions to other celestial bodies or for return from open space; e.g., Stardust probe. Unlike with military RVs, the advantage of the blunt body's lower TPS mass remained with space exploration entry vehicles like

4080-521: A stream of vaporized metal making it very visible to radar . These defects made the Mk-2 overly susceptible to anti-ballistic missile (ABM) systems. Consequently, an alternative sphere-cone RV to the Mk-2 was developed by General Electric. This new RV was the Mk-6 which used a non-metallic ablative TPS, a nylon phenolic. This new TPS was so effective as a reentry heat shield that significantly reduced bluntness

4216-411: A trailing vortex behind the entry vehicle. Correctly modelling the flow in the wake of an entry vehicle is very difficult. Thermal protection shield (TPS) heating in the vehicle's afterbody is usually not very high, but the geometry and unsteadiness of the vehicle's wake can significantly influence aerodynamics (pitching moment) and particularly dynamic stability. A thermal protection system , or TPS,

ASR-9 - Misplaced Pages Continue

4352-630: Is a set of programs to implement a suite of incremental changes to the National Airspace System (NAS). More precise Performance Based Navigation can reduce fuel burn, emissions, and noise exposure for a majority of communities, but the concentration of flight tracks also can increase noise exposure for people who live directly under those flight paths. A feature of the NextGen program is GPS-based waypoints, which result in consolidated flight paths for planes. The result of this change

4488-531: Is another entry vehicle geometry and was used with the X-23 PRIME (Precision Recovery Including Maneuvering Entry) vehicle. Objects entering an atmosphere from space at high velocities relative to the atmosphere will cause very high levels of heating . Atmospheric entry heating comes principally from two sources: As velocity increases, both convective and radiative heating increase, but at different rates. At very high speeds, radiative heating will dominate

4624-637: Is appointed for a five-year term. On March 19, 2019, President Donald Trump announced he would nominate Stephen Dickson, a former executive and pilot at Delta Air Lines , to be the next FAA Administrator. On July 24, 2019, the Senate confirmed Dickson by a vote of 52–40. He was sworn in as Administrator by Transportation Secretary Elaine Chao on August 12, 2019. On February 16, 2022, Dickson announced his resignation as FAA Administrator, effective March 31, 2022. In September 2023, President Joe Biden announced that he would be nominating Mike Whitaker to lead

4760-465: Is at 400,000 feet (122 km), the main heating during controlled entry takes place at altitudes of 65 to 35 kilometres (213,000 to 115,000 ft), peaking at 58 kilometres (190,000 ft). At typical reentry temperatures, the air in the shock layer is both ionized and dissociated . This chemical dissociation necessitates various physical models to describe the shock layer's thermal and chemical properties. There are four basic physical models of

4896-506: Is based upon a single ordinary differential equation and one algebraic equation. The five species model is based upon 5 ordinary differential equations and 17 algebraic equations. Because the 5 ordinary differential equations are tightly coupled, the system is numerically "stiff" and difficult to solve. The five species model is only usable for entry from low Earth orbit where entry velocity is approximately 7.8 km/s (28,000 km/h; 17,000 mph). For lunar return entry of 11 km/s,

5032-448: Is elegant and extremely useful for designing aircraft but assumes that the gas is chemically inert. From the standpoint of aircraft design, air can be assumed to be inert for temperatures less than 550 K (277 °C; 530 °F) at one atmosphere pressure. The perfect gas theory begins to break down at 550 K and is not usable at temperatures greater than 2,000 K (1,730 °C; 3,140 °F). For temperatures greater than 2,000 K,

5168-466: Is lower than other high-heat-flux-ablative materials, such as conventional carbon phenolics. PICA was patented by NASA Ames Research Center in the 1990s and was the primary TPS material for the Stardust aeroshell. The Stardust sample-return capsule was the fastest man-made object ever to reenter Earth's atmosphere, at 28,000 mph (ca. 12.5 km/s) at 135 km altitude. This was faster than

5304-528: Is pre-bonded to the aeroshell's structure thus enabling construction of a large heat shield. Phenolic-impregnated carbon ablator (PICA), a carbon fiber preform impregnated in phenolic resin , is a modern TPS material and has the advantages of low density (much lighter than carbon phenolic) coupled with efficient ablative ability at high heat flux. It is a good choice for ablative applications such as high-peak-heating conditions found on sample-return missions or lunar-return missions. PICA's thermal conductivity

5440-446: Is slowly reduced such that chemical reactions can continue then the gas can remain in equilibrium. However, it is possible for gas pressure to be so suddenly reduced that almost all chemical reactions stop. For that situation the gas is considered frozen. The distinction between equilibrium and frozen is important because it is possible for a gas such as air to have significantly different properties (speed-of-sound, viscosity etc.) for

5576-615: Is that many localities experience huge increases in air traffic over previously quiet areas. Complaints have risen with the added traffic and multiple municipalities have filed suit. As a result of the March 10, 2019 Ethiopian Airlines Flight 302 crash and the Lion Air Flight 610 crash five months earlier, most airlines and countries began grounding the Boeing 737 MAX 8 (and in many cases all MAX variants) due to safety concerns, but

ASR-9 - Misplaced Pages Continue

5712-457: Is the barrier that protects a spacecraft during the searing heat of atmospheric reentry. Multiple approaches for the thermal protection of spacecraft are in use, among them ablative heat shields, passive cooling, and active cooling of spacecraft surfaces. In general they can be divided into two categories: ablative TPS and reusable TPS. Ablative TPS are required when space craft reach a relatively low altitude before slowing down. Spacecraft like

5848-412: Is the only way of expending this, as it is highly impractical to use retrorockets for the entire reentry procedure. Ballistic warheads and expendable vehicles do not require slowing at reentry, and in fact, are made streamlined so as to maintain their speed. Furthermore, slow-speed returns to Earth from near-space such as high-altitude parachute jumps from balloons do not require heat shielding because

5984-453: Is typically better than that of a spherical section. The vehicle enters sphere-first. With a sufficiently small half-angle and properly placed center of mass, a sphere-cone can provide aerodynamic stability from Keplerian entry to surface impact. (The half-angle is the angle between the cone's axis of rotational symmetry and its outer surface, and thus half the angle made by the cone's surface edges.) The original American sphere-cone aeroshell

6120-490: The Columbia was upstream from the calculated value due to real-gas effects. On Columbia ' s maiden flight ( STS-1 ), astronauts John Young and Robert Crippen had some anxious moments during reentry when there was concern about losing control of the vehicle. An equilibrium real-gas model assumes that a gas is chemically reactive, but also assumes all chemical reactions have had time to complete and all components of

6256-482: The Airline Deregulation Act of 1978 phased out the CAB's economic regulation of the airlines. A nationwide strike by the air traffic controllers union in 1981 forced temporary flight restrictions but failed to shut down the airspace system. During the following year, the agency unveiled a new plan for further automating its air traffic control facilities, but progress proved disappointing. In 1994,

6392-506: The Boeing 737 MAX , following the crash of Ethiopian Airlines Flight 302 . Re-entry Atmospheric entry (sometimes listed as V impact or V entry ) is the movement of an object from outer space into and through the gases of an atmosphere of a planet , dwarf planet , or natural satellite . There are two main types of atmospheric entry: uncontrolled entry , such as the entry of astronomical objects , space debris , or bolides ; and controlled entry (or reentry ) of

6528-621: The Department of Commerce assumed primary responsibility for aviation oversight. In fulfilling its civil aviation responsibilities, the U.S. Department of Commerce initially concentrated on such functions as safety regulations and the certification of pilots and aircraft. It took over the building and operation of the nation's system of lighted airways, a task initiated by the Post Office Department . The Department of Commerce improved aeronautical radio communications—before

6664-642: The G77 Fortran compiler. A non-equilibrium real gas model is the most accurate model of a shock layer's gas physics, but is more difficult to solve than an equilibrium model. The simplest non-equilibrium model is the Lighthill-Freeman model developed in 1958. The Lighthill-Freeman model initially assumes a gas made up of a single diatomic species susceptible to only one chemical formula and its reverse; e.g., N 2 = N + N and N + N = N 2 (dissociation and recombination). Because of its simplicity,

6800-592: The Galileo Probe with a half-angle of 45° or the Viking aeroshell with a half-angle of 70°. Space exploration sphere-cone entry vehicles have landed on the surface or entered the atmospheres of Mars , Venus , Jupiter , and Titan . The biconic is a sphere-cone with an additional frustum attached. The biconic offers a significantly improved L/D ratio. A biconic designed for Mars aerocapture typically has an L/D of approximately 1.0 compared to an L/D of 0.368 for

6936-480: The Soyuz ), or unbounded (e.g., meteors ) trajectories. Various advanced technologies have been developed to enable atmospheric reentry and flight at extreme velocities. An alternative method of controlled atmospheric entry is buoyancy which is suitable for planetary entry where thick atmospheres, strong gravity, or both factors complicate high-velocity hyperbolic entry, such as the atmospheres of Venus , Titan and

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7072-611: The V-2 , stabilization and aerodynamic stress were important issues (many V-2s broke apart during reentry), but heating was not a serious problem. Medium-range missiles like the Soviet R-5 , with a 1,200-kilometer (650-nautical-mile) range, required ceramic composite heat shielding on separable reentry vehicles (it was no longer possible for the entire rocket structure to survive reentry). The first ICBMs , with ranges of 8,000 to 12,000 km (4,300 to 6,500 nmi), were only possible with

7208-608: The William J. Hughes Technical Center near Atlantic City, New Jersey , for support and research, and the Mike Monroney Aeronautical Center in Oklahoma City, Oklahoma , for training. The FAA has nine regional administrative offices: The Air Commerce Act of May 20, 1926, is the cornerstone of the U.S. federal government 's regulation of civil aviation. This landmark legislation was passed at

7344-648: The fuselage of an aircraft , but was prevented by supervisors he said were friendly with the airline. This was validated by a report by the Department of Transportation which found FAA managers had allowed Southwest Airlines to fly 46 airplanes in 2006 and 2007 that were overdue for safety inspections, ignoring concerns raised by inspectors. Audits of other airlines resulted in two airlines grounding hundreds of planes, causing thousands of flight cancellations. The House Transportation and Infrastructure Committee held hearings in April 2008. Jim Oberstar , former chairman of

7480-408: The giant planets . The concept of the ablative heat shield was described as early as 1920 by Robert Goddard : "In the case of meteors, which enter the atmosphere with speeds as high as 30 miles (48 km) per second, the interior of the meteors remains cold, and the erosion is due, to a large extent, to chipping or cracking of the suddenly heated surface. For this reason, if the outer surface of

7616-419: The isentropic chain . For a real gas, the isentropic chain is unusable and a Mollier diagram would be used instead for manual calculation. However, graphical solution with a Mollier diagram is now considered obsolete with modern heat shield designers using computer programs based upon a digital lookup table (another form of Mollier diagram) or a chemistry based thermodynamics program. The chemical composition of

7752-411: The 1960s had already brought the agency into the field of civil aviation security. In response to the hijackings on September 11, 2001, this responsibility is now primarily taken by the Department of Homeland Security . The FAA became more involved with the environmental aspects of aviation in 1968 when it received the power to set aircraft noise standards. Legislation in 1970 gave the agency management of

7888-548: The 70° sphere-cone entry vehicles sent by NASA to Mars other than the Mars Science Laboratory (MSL). SLA-561V begins significant ablation at a heat flux of approximately 110 W/cm , but will fail for heat fluxes greater than 300 W/cm . The MSL aeroshell TPS is currently designed to withstand a peak heat flux of 234 W/cm . The peak heat flux experienced by the Viking 1 aeroshell which landed on Mars

8024-417: The ASR-9 a technological advantage when compared to previously installed ASR systems; the radar systems before the ASR-9 had not been able to reject ground clutter when transmitting with the upper beam. Federal Aviation Administration The Federal Aviation Administration ( FAA ) is a U.S. federal government agency within the U.S. Department of Transportation which regulates civil aviation in

8160-400: The ASR-9 are nearly identical; however, a minimal displacement in height between the two beams causes a coverage change of approximately four degrees elevation. The upper beam on the ASR-9 is used primarily for short range reception, while the lower beam was mainly used for transmitting as well as long range reception. A combination of beam displacement, as well as a sharp underside cut off, gave

8296-420: The ASR-9 was far more advanced than processors that had been used on previous models. Some of the major areas that the digital processor was superior to earlier versions, the use of an optimum clutter filter bank, a fine-grained ground mapping threshold and mean level thresholding on the weather bands. Combining all of the upgraded components, the ASR-9 provided a significantly improved ability to detect aircraft in

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8432-448: The ASR-9's radar processor will ultimately enhance the amount of weather data the computer can process, leading to an even greater weather surveillance range of up to one hundred twenty nautical miles. The antenna used on the ASR-9 was a state of the art horned shaped reflector that forms two cosecant-squared beams to allow high elevation gain, as well as coverage up to forty-two degrees in elevation coverage. The two beams that pulse from

8568-576: The ASR-9, it was primarily to upgrade the aging ASR-4, -5 and -6 radar equipment at locations that did not receive the previous version, the ASR-8. The ASR-9 monitoring system was formally designated by the FAA to be used as a Primary Radar replacement, as well as a live weather condition monitor utilized from the Air Traffic Control tower. ASR-9 was the first Radar System to enable the detection of

8704-634: The Apollo mission capsules and 70% faster than the Shuttle. PICA was critical for the viability of the Stardust mission, which returned to Earth in 2006. Stardust's heat shield (0.81 m base diameter) was made of one monolithic piece sized to withstand a nominal peak heating rate of 1.2 kW/cm . A PICA heat shield was also used for the Mars Science Laboratory entry into the Martian atmosphere . An improved and easier to produce version called PICA-X

8840-787: The Apollo-CM. The higher L/D makes a biconic shape better suited for transporting people to Mars due to the lower peak deceleration. Arguably, the most significant biconic ever flown was the Advanced Maneuverable Reentry Vehicle (AMaRV). Four AMaRVs were made by the McDonnell Douglas Corp. and represented a significant leap in RV sophistication. Three AMaRVs were launched by Minuteman-1 ICBMs on 20 December 1979, 8 October 1980 and 4 October 1981. AMaRV had an entry mass of approximately 470 kg,

8976-676: The DC-X also served as the basis for an unsuccessful proposal for what eventually became the Lockheed Martin X-33 . Non- axisymmetric shapes have been used for crewed entry vehicles. One example is the winged orbit vehicle that uses a delta wing for maneuvering during descent much like a conventional glider. This approach has been used by the American Space Shuttle and the Soviet Buran . The lifting body

9112-504: The Earth under the influence of Earth's gravity , and are slowed by friction upon encountering Earth's atmosphere. Meteors are also often travelling quite fast relative to the Earth simply because their own orbital path is different from that of the Earth before they encounter Earth's gravity well . Most objects enter at hypersonic speeds due to their sub-orbital (e.g., intercontinental ballistic missile reentry vehicles), orbital (e.g.,

9248-419: The FAA and Boeing had colluded on recertification test flights, attempted to cover up important information and that the FAA had retaliated against whistleblowers. SpaceX CEO Elon Musk criticized the FAA as moving too slowly, after a 2020 launch of a Starship prototype rocket violated the company's license. Musk said the agency's regulations are tailored for "a handful of expendable launches per year from

9384-474: The FAA announced it will allow airlines to expand the passengers use of portable electronic devices during all phases of flight, but mobile phone calls would still be prohibited (and use of cellular networks during any point when aircraft doors are closed remains prohibited to-date). Implementation initially varied among airlines. The FAA expected many carriers to show that their planes allow passengers to safely use their devices in airplane mode , gate-to-gate, by

9520-834: The FAA called the Air Traffic Organization , (ATO) was set up by presidential executive order. This became the air navigation service provider for the airspace of the United States and for the New York (Atlantic) and Oakland (Pacific) oceanic areas. It is a full member of the Civil Air Navigation Services Organisation . The FAA issues a number of awards to holders of its certificates. Among these are demonstrated proficiencies as an aviation mechanic (the AMT Awards),

9656-483: The FAA declined to ground MAX 8 aircraft operating in the U.S. On March 12, the FAA said that its ongoing review showed "no systemic performance issues and provides no basis to order grounding the aircraft." Some U.S. Senators called for the FAA to ground the aircraft until an investigation into the cause of the Ethiopian Airlines crash was complete. U.S. Transportation Secretary Elaine Chao said that "If

9792-441: The FAA discriminated against qualified candidates. In December 2015, a reverse discrimination lawsuit was filed against the FAA seeking class-action status for the thousands of men and women who spent up to $ 40,000 getting trained under FAA rules before they were abruptly changed. The prospects of the lawsuit are unknown, as the FAA is a self-governing entity and therefore can alter and experiment with its hiring practices, and there

9928-514: The FAA identifies an issue that affects safety, the department will take immediate and appropriate action." The FAA resisted grounding the aircraft until March 13, 2019, when it received evidence of similarities in the two accidents. By then, 51 other regulators had already grounded the plane, and by March 18, 2019, all 387 aircraft in service were grounded. Three major U.S. airlines-- Southwest , United , and American Airlines —were affected by this decision. Further investigations also revealed that

10064-432: The FAA proposed to fine Southwest $ 10.2 million for failing to inspect older planes for cracks, and in 2009 Southwest and the FAA agreed that Southwest would pay a $ 7.5 million penalty and would adopt new safety procedures, with the fine doubling if Southwest failed to follow through. In 2014, the FAA modified its approach to air traffic control hiring. It launched more "off the street bids", allowing anyone with either

10200-431: The FAA shifted to a more step-by-step approach that has provided controllers with advanced equipment. In 1979, Congress authorized the FAA to work with major commercial airports to define noise pollution contours and investigate the feasibility of noise mitigation by residential retrofit programs. Throughout the 1980s, these charters were implemented. In the 1990s, satellite technology received increased emphasis in

10336-450: The FAA when acting under the authority of a DER appointment; a DER has no federal protection for work done or the decisions made as a DER. Neither does the FAA provide any indemnification for a DER from general tort law . "The FAA cannot shelter or protect DERs from the consequences of their findings." A DAR is an individual appointed in accordance with 14 CFR 183.33 who may perform examination, inspection, and testing services necessary to

10472-532: The FAA's development programs as a means to improvements in communications, navigation, and airspace management. In 1995, the agency assumed responsibility for safety oversight of commercial space transportation, a function begun eleven years before by an office within DOT headquarters. The agency was responsible for the decision to ground flights after the September 11 attacks . In December 2000, an organization within

10608-458: The FAA. Qualifications and policies for appointment of Designated Airworthiness Representatives are established in FAA Order 8100.8 , Designee Management Handbook . Working procedures for DERs are prescribed in FAA Order 8110.37 , Designated Engineering Representative (DER) Handbook . Neither type of DER is an employee of either the FAA or the United States government. While a DER represents

10744-446: The FAA. Whitaker previously served as deputy administrator of the FAA under President Barack Obama . The FAA has been cited as an example of regulatory capture , "in which the airline industry openly dictates to its regulators its governing rules, arranging for not only beneficial regulation, but placing key people to head these regulators." Retired NASA Office of Inspector General Senior Special Agent Joseph Gutheinz , who used to be

10880-733: The Federal Aviation Administration as it became one of several agencies (e.g., Federal Highway Administration, Federal Railroad Administration, the Coast Guard, and the Saint Lawrence Seaway Commission) within DOT. The FAA administrator no longer reported directly to the president, but instead to the Secretary of Transportation. New programs and budget requests would have to be approved by DOT, which would then include these requests in

11016-475: The International Community (commonly abbreviated as CANIC) is a notification from the FAA to civil airworthiness authorities of foreign countries of pending significant safety actions. The FAA Airworthiness Directives Manual, states the following: 8. Continued Airworthiness Notification to the International Community (CANIC). The FAA issued a CANIC to state the continued airworthiness of

11152-533: The Lighthill-Freeman model is a useful pedagogical tool, but is too simple for modelling non-equilibrium air. Air is typically assumed to have a mole fraction composition of 0.7812 molecular nitrogen, 0.2095 molecular oxygen and 0.0093 argon. The simplest real gas model for air is the five species model , which is based upon N 2 , O 2 , NO, N, and O. The five species model assumes no ionization and ignores trace species like carbon dioxide. When running

11288-488: The TPS bondline material thus leading to TPS failure. Consequently, for entry trajectories causing lower heat flux, carbon phenolic is sometimes inappropriate and lower-density TPS materials such as the following examples can be better design choices: SLA in SLA-561V stands for super light-weight ablator . SLA-561V is a proprietary ablative made by Lockheed Martin that has been used as the primary TPS material on all of

11424-517: The United States and surrounding international waters . Its powers include air traffic control , certification of personnel and aircraft , setting standards for airports, and protection of U.S. assets during the launch or re-entry of commercial space vehicles. Powers over neighboring international waters were delegated to the FAA by authority of the International Civil Aviation Organization . The FAA

11560-442: The accuracy. The Federal Aviation Administration has chosen different 35 sites around the United States to receive a Weather Systems Processor (WSP) upgrade to be added to the existing ASR-9's. This new processor monitored Doppler wind velocity, enabling the detection of low-altitude wind shear around airports. The Weather Systems Processor also improved the ASR-9's accuracy of precipitation reflectivity measurements taken by eliminating

11696-579: The aftermath of the Southwest Airlines inspection scandal, a bill was unanimously approved in the House to tighten regulations concerning airplane maintenance procedures, including the establishment of a whistleblower office and a two-year "cooling off" period that FAA inspectors or supervisors of inspectors must wait before they can work for those they regulated. The bill also required rotation of principal maintenance inspectors and stipulated that

11832-645: The airways. In 1936, the Bureau itself took over the centers and began to expand the ATC system. The pioneer air traffic controllers used maps, blackboards, and mental calculations to ensure the safe separation of aircraft traveling along designated routes between cities. In 1938, the Civil Aeronautics Act transferred the federal civil aviation responsibilities from the Commerce Department to

11968-407: The amount of ground clutter picked up by the radar sweeps. The WSP provided a velocity imagery, as well as full resolution reflectivity that extends all the way to the end of the ASR-9's monitor range of sixty nautical miles. The WSP sweep images are updated every 4.8 seconds, with a range of fifteen nautical miles where the processors operate the wind shear algorithms. Launching the upgrade program for

12104-442: The apparatus were to consist of layers of a very infusible hard substance with layers of a poor heat conductor between, the surface would not be eroded to any considerable extent, especially as the velocity of the apparatus would not be nearly so great as that of the average meteor." Practical development of reentry systems began as the range, and reentry velocity of ballistic missiles increased. For early short-range missiles, like

12240-422: The atmospheric entry returns to the same body that the vehicle had launched from, the event is referred to as reentry (almost always referring to Earth entry). The fundamental design objective in atmospheric entry of a spacecraft is to dissipate the energy of a spacecraft that is traveling at hypersonic speed as it enters an atmosphere such that equipment, cargo, and any passengers are slowed and land near

12376-469: The case of the Galileo probe's entry into Jupiter's atmosphere, the shock layer was mostly in equilibrium during peak heat flux due to the very high pressures experienced (this is counterintuitive given the free stream velocity was 39 km/s during peak heat flux). Determining the thermodynamic state of the stagnation point is more difficult under an equilibrium gas model than a perfect gas model. Under

12512-402: The center of curvature (dynamic stability is more problematic). Pure spheres have no lift. However, by flying at an angle of attack , a spherical section has modest aerodynamic lift thus providing some cross-range capability and widening its entry corridor. In the late 1950s and early 1960s, high-speed computers were not yet available and computational fluid dynamics was still embryonic. Because

12648-426: The committee, said its investigation uncovered a pattern of regulatory abuse and widespread regulatory lapses, allowing 117 aircraft to be operated commercially although not in compliance with FAA safety rules . Oberstar said there was a "culture of coziness" between senior FAA officials and the airlines and "a systematic breakdown" in the FAA's culture that resulted in "malfeasance, bordering on corruption". In 2008

12784-418: The convective heat fluxes, as radiative heating is proportional to the eighth power of velocity, while convective heating is proportional to the third power of velocity. Radiative heating thus predominates early in atmospheric entry, while convection predominates in the later phases. During certain intensity of ionization, a radio-blackout with the spacecraft is produced. While NASA's Earth entry interface

12920-524: The development of modern ablative heat shields and blunt-shaped vehicles. In the United States, this technology was pioneered by H. Julian Allen and A. J. Eggers Jr. of the National Advisory Committee for Aeronautics (NACA) at Ames Research Center . In 1951, they made the counterintuitive discovery that a blunt shape (high drag) made the most effective heat shield. From simple engineering principles, Allen and Eggers showed that

13056-564: The dice and taking the chance on getting caught. He also said the FAA is often too quick to bend to pressure from airlines and pilots." Other experts have been critical of the constraints and expectations under which the FAA is expected to operate. The dual role of encouraging aerospace travel and regulating aerospace travel are contradictory. For example, to levy a heavy penalty upon an airline for violating an FAA regulation which would impact their ability to continue operating would not be considered encouraging aerospace travel. On July 22, 2008, in

13192-571: The downing of Malaysia Airlines Flight 17 , the FAA suspended flights by U.S. airlines to Ben Gurion Airport during the 2014 Israel–Gaza conflict for 24 hours. The ban was extended for a further 24 hours but was lifted about six hours later. The FAA Reauthorization Act of 2018 gives the FAA one year to establish minimum pitch, width and length for airplane seats, to ensure they are safe for passengers. The first FAA licensed orbital human space flight took place on November 15, 2020 , carried out by SpaceX on behalf of NASA. The administrator

13328-449: The end of 2013. Devices must be held or put in the seat-back pocket during the actual takeoff and landing. Mobile phones must be in airplane mode or with mobile service disabled, with no signal bars displayed, and cannot be used for voice communications due to Federal Communications Commission regulations that prohibit any airborne calls using mobile phones. From a technological standpoint, cellular service would not work in-flight because of

13464-543: The founding of the Federal Communications Commission in 1934, which handles most such matters today—and introduced radio beacons as an effective aid to air navigation. The Aeronautics Branch was renamed the Bureau of Air Commerce in 1934 to reflect its enhanced status within the Department. As commercial flying increased, the Bureau encouraged a group of airlines to establish the first three centers for providing air traffic control (ATC) along

13600-447: The gas and varying the different molecular combinations of the elements through numerical iteration until the lowest possible Gibbs free energy is calculated (a Newton–Raphson method is the usual numerical scheme). The data base for a Gibbs free energy program comes from spectroscopic data used in defining partition functions . Among the best equilibrium codes in existence is the program Chemical Equilibrium with Applications (CEA) which

13736-432: The gas have the same temperature (this is called thermodynamic equilibrium ). When air is processed by a shock wave, it is superheated by compression and chemically dissociates through many different reactions. Direct friction upon the reentry object is not the main cause of shock-layer heating. It is caused mainly from isentropic heating of the air molecules within the compression wave. Friction based entropy increases of

13872-648: The gravitational acceleration of an object starting at relative rest from within the atmosphere itself (or not far above it) cannot create enough velocity to cause significant atmospheric heating. For Earth, atmospheric entry occurs by convention at the Kármán line at an altitude of 100 km (62 miles; 54 nautical miles) above the surface, while at Venus atmospheric entry occurs at 250 km (160 mi; 130 nmi) and at Mars atmospheric entry at about 80 km (50 mi; 43 nmi). Uncontrolled objects reach high velocities while accelerating through space toward

14008-408: The heat load experienced by an entry vehicle was inversely proportional to the drag coefficient ; i.e., the greater the drag, the less the heat load. If the reentry vehicle is made blunt, air cannot "get out of the way" quickly enough, and acts as an air cushion to push the shock wave and heated shock layer forward (away from the vehicle). Since most of the hot gases are no longer in direct contact with

14144-444: The hot shock layer gas away from the heat shield's outer wall (creating a cooler boundary layer ). The boundary layer comes from blowing of gaseous reaction products from the heat shield material and provides protection against all forms of heat flux. The overall process of reducing the heat flux experienced by the heat shield's outer wall by way of a boundary layer is called blockage . Ablation occurs at two levels in an ablative TPS:

14280-538: The issuance of certificates. There are two types of DARs: manufacturing, and maintenance. Specialized Experience – Amateur-Built and Light-Sport Aircraft DARs Both Manufacturing DARs and Maintenance DARs may be authorized to perform airworthiness certification of light-sport aircraft. DAR qualification criteria and selection procedures for amateur-built and light-sport aircraft airworthiness functions are provided in Order 8100.8. A Continued Airworthiness Notification to

14416-438: The molecules within the wave also account for some heating. The distance from the shock wave to the stagnation point on the entry vehicle's leading edge is called shock wave stand off . An approximate rule of thumb for shock wave standoff distance is 0.14 times the nose radius. One can estimate the time of travel for a gas molecule from the shock wave to the stagnation point by assuming a free stream velocity of 7.8 km/s and

14552-505: The object, but also by drag. These forces can cause loss of mass ( ablation ) or even complete disintegration of smaller objects, and objects with lower compressive strength can explode. Reentry has been achieved with speeds ranging from 7.8 km/s for low Earth orbit to around 12.5 km/s for the Stardust probe. Crewed space vehicles must be slowed to subsonic speeds before parachutes or air brakes may be deployed. Such vehicles have high kinetic energies, and atmospheric dissipation

14688-481: The outer surface of the TPS material chars, melts, and sublimes , while the bulk of the TPS material undergoes pyrolysis and expels product gases. The gas produced by pyrolysis is what drives blowing and causes blockage of convective and catalytic heat flux. Pyrolysis can be measured in real time using thermogravimetric analysis , so that the ablative performance can be evaluated. Ablation can also provide blockage against radiative heat flux by introducing carbon into

14824-569: The overall budget and submit it to the president. At the same time, a new National Transportation Safety Board took over the Civil Aeronautics Board's (CAB) role of investigating and determining the causes of transportation accidents and making recommendations to the secretary of transportation. CAB was merged into DOT with its responsibilities limited to the regulation of commercial airline routes and fares. The FAA gradually assumed additional functions. The hijacking epidemic of

14960-479: The presence of ground clutter, or weather clutter such as torrential rains. The new and improved processor on the ASR-9 also enhances the ability to detect hazardous weather conditions that could affect flight, landing and take off of various aircraft. A new solid state design and Remote Maintenance Monitoring significantly improved the overall availabilities of the ASR-9, as well as lowering the monthly operation costs. When Westinghouse first started development of

15096-588: The promotion of aviation safety. The FAA Safety Team, or FAASTeam, works with Volunteers at several levels and promotes safety education and outreach nationwide. On March 18, 2008, the FAA ordered its inspectors to reconfirm that airlines are complying with federal rules after revelations that Southwest Airlines flew dozens of aircraft without certain mandatory inspections. The FAA exercises surprise Red Team drills on national airports annually. On October 31, 2013, after outcry from media outlets, including heavy criticism from Nick Bilton of The New York Times ,

15232-409: The rapid speed of the airborne aircraft: mobile phones cannot switch fast enough between cellular towers at an aircraft's high speed. However, the ban is due to potential radio interference with aircraft avionics. If an air carrier provides Wi-Fi service during flight, passengers may use it. Short-range Bluetooth accessories, like wireless keyboards , can also be used. In July 2014, in the wake of

15368-515: The same committee sent before a meeting to discuss air traffic control privatization noted a 35-year legacy of failed air traffic control modernization management, including NextGen. The letter said the FAA initially described NextGen as fundamentally transforming how air traffic would be managed. In 2015, however, the National Research Council noted that NextGen, as currently executed, was not broadly transformational and that it

15504-451: The same thermodynamic state; e.g., pressure and temperature. Frozen gas can be a significant issue in the wake behind an entry vehicle. During reentry, free stream air is compressed to high temperature and pressure by the entry vehicle's shock wave. Non-equilibrium air in the shock layer is then transported past the entry vehicle's leading side into a region of rapidly expanding flow that causes freezing. The frozen air can then be entrained into

15640-430: The shock layer between the shock wave and leading edge of an entry vehicle is chemically reacting and not in a state of equilibrium. The Fay–Riddell equation , which is of extreme importance towards modeling heat flux, owes its validity to the stagnation point being in chemical equilibrium. The time required for the shock layer gas to reach equilibrium is strongly dependent upon the shock layer's pressure. For example, in

15776-447: The shock layer contains a significant amount of ionized nitrogen and oxygen. The five-species model is no longer accurate and a twelve-species model must be used instead. Atmospheric entry interface velocities on a Mars–Earth trajectory are on the order of 12 km/s (43,000 km/h; 27,000 mph). Modeling high-speed Mars atmospheric entry—which involves a carbon dioxide, nitrogen and argon atmosphere—is even more complex requiring

15912-589: The shock layer thus making it optically opaque. Radiative heat flux blockage was the primary thermal protection mechanism of the Galileo Probe TPS material (carbon phenolic). Early research on ablation technology in the USA was centered at NASA 's Ames Research Center located at Moffett Field , California. Ames Research Center was ideal, since it had numerous wind tunnels capable of generating varying wind velocities. Initial experiments typically mounted

16048-399: The shock wave dissociating ambient atmospheric gas followed by recombination within the shock layer into new molecular species. The newly formed diatomic molecules initially have a very high vibrational temperature that efficiently transforms the vibrational energy into radiant energy ; i.e., radiative heat flux. The whole process takes place in less than a millisecond which makes modelling

16184-408: The space shuttle are designed to slow down at high altitude so that they can use reuseable TPS. (see: Space Shuttle thermal protection system ). Thermal protection systems are tested in high enthalpy ground testing or plasma wind tunnels that reproduce the combination of high enthalpy and high stagnation pressure using Induction plasma or DC plasma. The ablative heat shield functions by lifting

16320-471: The spherical section geometry in crewed capsules are Soyuz / Zond , Gemini , and Mercury . Even these small amounts of lift allow trajectories that have very significant effects on peak g-force , reducing it from 8–9 g for a purely ballistic (slowed only by drag) trajectory to 4–5 g, as well as greatly reducing the peak reentry heat. The sphere-cone is a spherical section with a frustum or blunted cone attached. The sphere-cone's dynamic stability

16456-483: The spherical section was amenable to closed-form analysis, that geometry became the default for conservative design. Consequently, crewed capsules of that era were based upon the spherical section. Pure spherical entry vehicles were used in the early Soviet Vostok and Voskhod capsules and in Soviet Mars and Venera descent vehicles. The Apollo command module used a spherical section forebody heat shield with

16592-524: The urging of the aviation industry, whose leaders believed the airplane could not reach its full commercial potential without federal action to improve and maintain safety standards. The Act charged the Secretary of Commerce with fostering air commerce, issuing and enforcing air traffic rules, licensing pilots , certifying aircraft, establishing airways, and operating and maintaining aids to air navigation. The newly created Aeronautics Branch, operating under

16728-455: The vehicle, the heat energy would stay in the shocked gas and simply move around the vehicle to later dissipate into the atmosphere. The Allen and Eggers discovery, though initially treated as a military secret, was eventually published in 1958. When atmospheric entry is part of a spacecraft landing or recovery, particularly on a planetary body other than Earth, entry is part of a phase referred to as entry, descent, and landing , or EDL. When

16864-409: The war. The application of radar to ATC helped controllers in their drive to keep abreast of the postwar boom in commercial air transportation. In 1946, meanwhile, Congress gave CAA the added task of administering the federal-aid airport program, the first peacetime program of financial assistance aimed exclusively at development of the nation's civil airports. The approaching era of jet travel (and

17000-479: The word "customer" properly applies to the flying public, not those entities regulated by the FAA. The bill died in a Senate committee that year. In September 2009, the FAA administrator issued a directive mandating that the agency use the term "customers" to refer to only the flying public. In 2007, two FAA whistleblowers , inspectors Charalambe "Bobby" Boutris and Douglas E. Peters, alleged that Boutris said he attempted to ground Southwest after finding cracks in

17136-402: Was 21 W/cm . For Viking 1 , the TPS acted as a charred thermal insulator and never experienced significant ablation. Viking 1 was the first Mars lander and based upon a very conservative design. The Viking aeroshell had a base diameter of 3.54 meters (the largest used on Mars until Mars Science Laboratory). SLA-561V is applied by packing the ablative material into a honeycomb core that

17272-624: Was a former Air Force general and adviser to President Eisenhower . The same year witnessed the birth of the National Aeronautics and Space Administration (NASA), which was created in response to the Soviet Union (USSR) launch of the first manmade satellite. NASA assumed NACA's aeronautical research role. In 1967, a new U.S. Department of Transportation (DOT) combined major federal responsibilities for air and surface transport. The Federal Aviation Agency's name changed to

17408-418: Was controlled through a split body flap (also called a split-windward flap ) along with two yaw flaps mounted on the vehicle's sides. Hydraulic actuation was used for controlling the flaps. AMaRV was guided by a fully autonomous navigation system designed for evading anti-ballistic missile (ABM) interception. The McDonnell Douglas DC-X (also a biconic) was essentially a scaled-up version of AMaRV. AMaRV and

17544-644: Was created in August ;1958  ( 1958-08 ) as the Federal Aviation Agency, replacing the Civil Aeronautics Administration (CAA). In 1967, the FAA became part of the newly formed U.S. Department of Transportation and was renamed the Federal Aviation Administration. The FAA's roles include: The FAA operates five "lines of business". Their functions are: The FAA is headquartered in Washington, D.C. , and also operates

17680-657: Was developed by SpaceX in 2006–2010 for the Dragon space capsule . The first reentry test of a PICA-X heat shield was on the Dragon C1 mission on 8 December 2010. The PICA-X heat shield was designed, developed and fully qualified by a small team of a dozen engineers and technicians in less than four years. PICA-X is ten times less expensive to manufacture than the NASA PICA heat shield material. A second enhanced version of PICA—called PICA-3—was developed by SpaceX during

17816-544: Was just sufficiently understood to ensure Apollo's success. However, radiative heat flux in carbon dioxide (Mars entry) is still barely understood and will require major research. The frozen gas model describes a special case of a gas that is not in equilibrium. The name "frozen gas" can be misleading. A frozen gas is not "frozen" like ice is frozen water. Rather a frozen gas is "frozen" in time (all chemical reactions are assumed to have stopped). Chemical reactions are normally driven by collisions between molecules. If gas pressure

17952-438: Was never any guarantee of a job in the CTI program. In August 2023 The New York Times published an investigative report that showed overworked air traffic controllers at understaffed facilities making errors that resulted in 46 near collisions in the air and on the ground in the month of July alone. A May 2017 letter from staff of the U.S. House of Representatives Committee on Transportation and Infrastructure to members of

18088-498: Was possible. However, the Mk-6 was a huge RV with an entry mass of 3,360 kg, a length of 3.1 m and a half-angle of 12.5°. Subsequent advances in nuclear weapon and ablative TPS design allowed RVs to become significantly smaller with a further reduced bluntness ratio compared to the Mk-6. Since the 1960s, the sphere-cone has become the preferred geometry for modern ICBM RVs with typical half-angles being between 10° and 11°. Reconnaissance satellite RVs (recovery vehicles) also used

18224-499: Was responsible for ATC, airman and aircraft certification, safety enforcement, and airway development. CAB was entrusted with safety regulation, accident investigation, and economic regulation of the airlines. The CAA was part of the Department of Commerce. The CAB was an independent federal agency. On the eve of America's entry into World War II , CAA began to extend its ATC responsibilities to takeoff and landing operations at airports. This expanded role eventually became permanent after

18360-604: Was the Mk-2 RV (reentry vehicle), which was developed in 1955 by the General Electric Corp. The Mk-2's design was derived from blunt-body theory and used a radiatively cooled thermal protection system (TPS) based upon a metallic heat shield (the different TPS types are later described in this article). The Mk-2 had significant defects as a weapon delivery system, i.e., it loitered too long in the upper atmosphere due to its lower ballistic coefficient and also trailed

18496-483: Was written by Bonnie J. McBride and Sanford Gordon at NASA Lewis (now renamed "NASA Glenn Research Center"). Other names for CEA are the "Gordon and McBride Code" and the "Lewis Code". CEA is quite accurate up to 10,000 K for planetary atmospheric gases, but unusable beyond 20,000 K ( double ionization is not modelled). CEA can be downloaded from the Internet along with full documentation and will compile on Linux under

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