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33-411: The seat is considered third generation and includes advanced features. For example, it senses the conditions of the ejection (airspeed and altitude) and selects the appropriate drogue and main parachute deployments to minimize the forces on the occupant. The seat is controlled by a fully redundant digital electronic sequencer which makes the decisions and initiates the appropriate seat components to allow

66-517: A 0 5 T T 0 [ ( q c P + 1 ) 2 7 − 1 ] , {\displaystyle \mathrm {TAS} =a_{0}{\sqrt {{\frac {5T}{T_{0}}}\left[\left({\frac {q_{c}}{P}}+1\right)^{\frac {2}{7}}-1\right]}},} where: Electronic flight instrument systems (EFIS) contain an air data computer with inputs of impact pressure, static pressure and total air temperature . In order to compute TAS,

99-480: A TAS meter is necessary for navigation purposes at cruising altitude in less dense air. The IAS meter reads very nearly the TAS at lower altitude and at lower speed. On jet airliners the TAS meter is usually hidden at speeds below 200 knots (370 km/h). Neither provides for accurate speed over the ground , since surface winds or winds aloft are not taken into account. TAS is the appropriate speed to use when calculating

132-625: A function of EAS and air density: T A S = E A S ρ ρ 0 {\displaystyle \mathrm {TAS} ={\frac {\mathrm {EAS} }{\sqrt {\frac {\rho }{\rho _{0}}}}}} where TAS can be calculated as a function of Mach number and static air temperature: T A S = a 0 M T T 0 , {\displaystyle \mathrm {TAS} ={a_{0}}M{\sqrt {T \over T_{0}}},} where For manual calculation of TAS in knots, where Mach number and static air temperature are known,

165-663: A specific percentage of the speed of sound. Usually passenger airliners do not fly faster than around 85% of speed of sound, or Mach 0.85. Supersonic aircraft, like the Concorde and military fighters, use the Machmeter as the main speed instrument with the exception of take-offs and landings. Some aircraft also have a taxi speed indicator for use on the ground. Since the IAS often starts at around 74–93 km/h (40–50 kn) (on jet airliners), pilots may need extra help while taxiing

198-563: Is achieved by deploying the main parachute immediately after exiting the cockpit. It is the only ejection seat that can deploy the main parachute this early in the ejection sequence. The ACES seat was originally developed and produced in Long Beach, CA by McDonnell Douglas. Weber Aircraft company also produced the seat as part of a USAF mandated "leader/follower" program. In the late 1980s the McDonnell Douglas production line

231-423: Is an important value for the pilot because it is the indicated speeds which are specified in the aircraft flight manual for such important performance values as the stall speed . These speeds, in true airspeed terms, vary considerably depending upon density altitude . However, at typical civilian operating speeds, the aircraft's aerodynamic structure responds to dynamic pressure alone, and the aircraft will perform

264-515: Is necessary to convert IAS to TAS and/or ground speed (GS) using the following method: With the advent of Doppler radar navigation and, more recently, GPS receivers, with other advanced navigation equipment that allows pilots to read ground speed directly, the TAS calculation in-flight is becoming unnecessary for the purposes of navigation estimations. TAS is the primary method to determine aircraft's cruise performance in manufacturer's specs, speed comparisons and pilot reports. From IAS,

297-452: Is not the actual speed through the air even when the aircraft is at sea level under International Standard Atmosphere conditions (15 °C, 1013 hPa , 0% humidity). The IAS needs to be corrected for known instrument and position errors to show true airspeed under those specific atmospheric conditions, and this is the CAS (Calibrated Airspeed). Despite this the pilot's primary airspeed reference,

330-589: Is temperature-dependent and pressure-dependent, according to the ideal gas law . At sea level in the International Standard Atmosphere (ISA) and at low speeds where air compressibility is negligible (i.e., assuming a constant air density), IAS corresponds to TAS. When the air density or temperature around the aircraft differs from standard sea level conditions, IAS will no longer correspond to TAS, thus it will no longer reflect aircraft performance. The ASI will indicate less than TAS when

363-435: Is the airspeed of an aircraft as measured by its pitot-static system and displayed by the airspeed indicator (ASI). This is the pilots' primary airspeed reference. This value is not corrected for installation error, instrument error , or the actual encountered air density , being instead calibrated to always reflect the adiabatic compressible flow of the International Standard Atmosphere at sea level. It uses

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396-650: Is the pilot's primary airspeed reference when operating below transonic or supersonic speeds. Indicated airspeed measured by pitot-tube can be approximately expressed by the following equation delivered from Bernoulli's equation . NOTE: The above equation applies only to conditions that can be treated as incompressible. Liquids are treated as incompressible under almost all conditions. Gases under certain conditions can be approximated as incompressible. See Compressibility . The compression effects can be corrected by use of Poisson constant . This compensation corresponds to equivalent airspeed (EAS) . where: The IAS

429-600: The Goodrich Corporation . In 2018, UTC acquired Rockwell Collins, Inc. and combined it with UTC Aerospace Systems to form Collins Aerospace. Today the ACES seat product line continues to be manufactured by Collins Aerospace Specialty Seating in Colorado Springs, Colorado & Collins Aerospace Universal Propulsion Co. Fairfield, California. Indicated airspeed Indicated airspeed ( IAS )

462-636: The 103 lb small female aircrew gets a similar acceleration to the 245 lb male pilot. The seat has been updated over the years through pre-planned product improvement programs to include digital sequencing, additional redundancy, enhance stability, limb restraints, structural upgrading, and passive head/neck restraints. The ACES II seat ejection injury rate is one of the lowest in the world as proven in over 600 live ejections. Back injury rates occur in only 1% of ACES ejections compared to 20% to 40% in most other ejection seats. The A-10, F-15, F-117, B-1, and B-2 use connected firing handles that activate both

495-450: The ASI, shows IAS (by definition). The relationship between CAS and IAS is known and documented for each aircraft type and model. The aircraft's pilot manual usually gives critical V speeds as IAS, those speeds indicated by the airspeed indicator. This is because the aircraft behaves similarly at the same IAS no matter what the TAS is: E.g. A pilot landing at a hot and high airfield will use

528-570: The Mach speed. Mach incorporates the above data including the compressibility factor. Modern aircraft instrumentation use an air data computer to perform this calculation in real time and display the TAS reading directly on the electronic flight instrument system . Since temperature variations are of a smaller influence, the ASI error can be estimated as indicating about 2% less than TAS per 1,000 feet (300 m) of altitude above sea level. For example, an aircraft flying at 15,000 feet (4,600 m) in

561-461: The actual speed that the aircraft uses compared to the ground. This is usually connected to a GPS or similar system. Ground speed is just a pilot aid to estimate if the flight is on time, behind or ahead of schedule. It is not used for takeoff and landing purposes, since the imperative speed for a flying aircraft always is the speed against the wind. The Machmeter is, on subsonic aircraft, a warning indicator. Subsonic aircraft must not fly faster than

594-564: The air data computer must convert total air temperature to static air temperature. This is also a function of Mach number: T = T t 1 + 0.2 M 2 , {\displaystyle T={\frac {T_{\text{t}}}{1+0.2M^{2}}},} where In simple aircraft, without an air data computer or machmeter , true airspeed can be calculated as a function of calibrated airspeed and local air density (or static air temperature and pressure altitude, which determine density). Some airspeed indicators incorporate

627-463: The air density decreases due to a change in altitude or air temperature. For this reason, TAS cannot be measured directly. In flight, it can be calculated either by using an E6B flight calculator or its equivalent. For low speeds, the data required are static air temperature , pressure altitude and IAS (or CAS for more precision). Above approximately 100 knots (190 km/h), the compressibility error rises significantly and TAS must be calculated by

660-433: The aircraft changes altitude, IAS varies considerably from true airspeed (TAS), the relative velocity between the aircraft and the surrounding air mass. Calibrated airspeed (CAS) is the IAS corrected for instrument and position error . An aircraft's indicated airspeed in knots is typically abbreviated KIAS for " Knots -Indicated Air Speed" (vs. KCAS for calibrated airspeed and KTAS for true airspeed ). The IAS

693-475: The aircraft on the ground. Its range is around 0–93 km/h (0–50 kn). True airspeed The true airspeed ( TAS ; also KTAS , for knots true airspeed ) of an aircraft is the speed of the aircraft relative to the air mass through which it is flying. The true airspeed is important information for accurate navigation of an aircraft. Traditionally it is measured using an analogue TAS indicator , but as GPS has become available for civilian use,

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726-523: The canopy jettison systems, and the seat ejection. Both handles accomplish the same task, so pulling either one suffices. The F-22, WB-57, and F-16 have only one handle located between the pilot's legs, due to cockpit space limitations. The minimal ejection altitude for ACES II seat in inverted flight is about 140 feet (43 m) above ground level at 150 KIAS . The seat performance is in accordance with MIL-S-9479 as tailored for each aircraft application. Excellent terrain clearance performance under 250 KEAS

759-456: The difference between total pressure and static pressure, provided by the system, to either mechanically or electronically measure dynamic pressure . The dynamic pressure includes terms for both density and airspeed. Since the airspeed indicator cannot know the density, it is by design calibrated to assume the sea level standard atmospheric density when calculating airspeed. Since the actual density will vary considerably from this assumed value as

792-423: The expression may be simplified to T A S = 39 M T {\displaystyle \mathrm {TAS} =39M{\sqrt {T}}} (remembering temperature is in kelvins). Combining the above with the expression for Mach number gives an expression for TAS as a function of impact pressure , static pressure and static air temperature (valid for subsonic flow): T A S =

825-420: The following speeds can also be calculated: On large jet aircraft the IAS is by far the most important speed indicator. Most aircraft speed limitations are based on IAS, as IAS closely reflects dynamic pressure. TAS is usually displayed as well, but purely for advisory information and generally not in a prominent location. Modern jet airliners also include ground speed (GS) and Machmeter . Ground speed shows

858-448: The importance of such air-measuring instruments has decreased. Since indicated , as opposed to true , airspeed is a better indicator of margin above the stall , true airspeed is not used for controlling the aircraft; for these purposes the indicated airspeed – IAS or KIAS (knots indicated airspeed) – is used. However, since indicated airspeed only shows true speed through the air at standard sea level pressure and temperature,

891-669: The international standard atmosphere with an IAS of 100 knots (190 km/h), is actually flying at 126 knots (233 km/h) TAS. To maintain a desired ground track while flying in the moving airmass, the pilot of an aircraft must use knowledge of wind speed, wind direction, and true air speed to determine the required heading. See also wind triangle . At low speeds and altitudes, IAS and CAS are close to equivalent airspeed (EAS). ρ 0 ( E A S ) 2 = ρ ( T A S ) 2 {\displaystyle \rho _{0}(EAS)^{2}=\rho (TAS)^{2}} TAS can be calculated as

924-408: The range of an airplane. It is the speed normally listed on the flight plan, also used in flight planning, before considering the effects of wind. The airspeed indicator (ASI), driven by ram air into a pitot tube and still air into a barometric static port, shows what is called indicated airspeed (IAS). The differential pressure is affected by air density . The ratio between the two measurements

957-405: The same IAS to fly the aircraft at the correct approach and landing speeds as when landing at a cold sea level airfield, even though the TAS must differ considerably between the two landings. Whereas IAS can be reliably used for monitoring critical speeds well below the speed of sound this is not so at higher speeds. An example: Because (1) the compressibility of air changes considerably approaching

990-462: The same when at the same dynamic pressure. Since it is this same dynamic pressure that drives the airspeed indicator, an aircraft will always, for example, stall at the published indicated airspeed (for the current configuration) regardless of density, altitude or true airspeed. Furthermore, the IAS is specified in some regulations, and by air traffic control when directing pilots, since the airspeed indicator displays that speed (by definition) and it

1023-413: The seat to fly through the air and safely descend the aircrew to the ground. The sequencer includes a crash data recorder that contains ejection information that can be later analyzed during crash investigations to understand the dynamics of the ejection as well as loads on the aircrew during the event. The seat propulsion system is specially designed with technology to compensate for aircrew weight so that

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1056-445: The speed of sound, and (2) the speed of sound varies considerably with temperature and therefore altitude; the maximum speed at which an aircraft structure is safe, the never exceed speed (abbreviated V NE ), is specified at several differing altitudes in faster aircraft's operating manuals, as shown in the sample table below. Ref: Pilot's Notes for Tempest V Sabre IIA Engine - Air Ministry A.P.2458C-PN For navigation, it

1089-647: Was relocated from Long Beach, CA to Titusville, FL. The Weber Aircraft ACES production line eventually closed as USAF needs for ejection seats declined. In the late 1990s, Boeing and McDonnell Douglas merged with the combined company retaining the Boeing name. In 1999, Goodrich acquired the ACES product line from Boeing and eventually relocated the production line to Colorado Springs to the Aircraft Manufactures Inc. (AMI) facility owned by Goodrich. In 2012, United Technologies Corporation (UTC) acquired

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