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75-732: The McDonnell Douglas YC-15 is a prototype four-engine short take-off and landing (STOL) tactical transport. It was McDonnell Douglas ' entrant into the United States Air Force 's Advanced Medium STOL Transport (AMST) competition to replace the Lockheed C-130 Hercules as the USAF's standard STOL tactical transport. In the end, neither the YC-15 nor the Boeing YC-14 was ordered into production, although

150-715: A Fairchild A-10 , anti-tipover stabilizer struts from the Lockheed C-141 Starlifter , pumps taken from the McDonnell Douglas F-15 Eagle , Lockheed C-5 Galaxy , DC-9 and C-141 and actuators taken from the C-5 Galaxy and DC-10. In addition, the environmental cooling system was composed of components taken from the DC-9, C-141 and Boeing KC-135 . The YC-15 interior cargo hold was large, with dimensions 47 x 11.8 x 11.4 feet. The YC-15

225-566: A different Boeing aircraft ). The KC-135 was the United States Air Force (USAF)'s first jet-powered refueling tanker and replaced the KC-97 Stratofreighter . The KC-135 was initially tasked with refueling strategic bombers, but it was used extensively in the Vietnam War and later conflicts such as Operation Desert Storm to extend the range and endurance of US tactical fighters and bombers. The KC-135 entered service with

300-429: A horizontal stabilizer mounted on the fuselage near the bottom of the vertical stabilizer with positive dihedral on the two horizontal planes and a hi-frequency radio antenna which protrudes forward from the top of the vertical fin or stabilizer. These basic features make it strongly resemble the commercial Boeing 707 and 720 aircraft, although it is a different aircraft. Reconnaissance and command post variants of

375-507: A 100% increase compared to the original J57 engine. The modified tanker, designated KC-135R (modified KC-135A or E) or KC-135T (modified KC-135Q), can offload up to 50% more fuel (on a long-duration sortie), is 25% more fuel-efficient, and costs 25% less to operate than with the previous engines. It is also significantly quieter than the KC-135A, with noise levels at takeoff reduced from 126 to 99 decibels . This 27 dB noise reduction results in

450-662: A 27,000-pound (12,000 kg) payload and a 400-nautical-mile (460 mi; 740 km) mission radius. For comparison, the C-130 of that era required about 4,000 feet (1,200 m) for this load. Proposals were submitted by Bell , Boeing , Fairchild , McDonnell Douglas and the Lockheed / North American Rockwell team at this stage of the competition. On 10 November 1972, the two top bids (from Boeing and McDonnell Douglas) were selected. The companies were awarded development contracts for two prototypes each. McDonnell Douglas' prototype

525-467: A 50-foot (15 meters) obstacle within 1,500 feet (450 meters) of commencing takeoff or in landing, to stop within 1,500 feet (450 meters) after passing over a 50-foot (15 meters) obstacle. Also called STOL. STOL (Short Take Off and Landing). STOL performance of an aircraft is the ability of aircraft to take off and clear a 50-foot obstruction in a distance of 1,500 feet from beginning the takeoff run. It must also be able to stop within 1,500 feet after crossing

600-443: A 50-foot obstacle on landing. An aircraft that, at some weight within its approved operating weight, is capable of operating from a STOL runway in compliance with the applicable STOL characteristics and airworthiness, operations, noise, and pollution standards" and ""aircraft" means any machine capable of deriving support in the atmosphere A STOL aircraft is an aircraft with a certified performance capability to execute approaches along

675-467: A 50-ft (15-m) obstacle at the end of that distance and upon landing can clear the same obstacle and then land within 1,000 ft. The STOL mode of flight is one during which an airplane taking off or landing is operated at climb-out and approach speeds lower than the conventionally accepted margins of airspeed above the power-off stalling speed of the airplane. Additionally, some aircraft manufacturers market their products as STOL without providing evidence that

750-475: A Boeing or LTV receiver system and a secure voice SATCOM radio. Three of the aircraft (60-0356, -0357, and -0362) were converted to tankers from RC-135Ds, from which they retained their added equipment. KC-135Q re-engined with CFM56 engines, 54 modified. A new-built variant for France as dual-role tanker/cargo and troop carrier aircraft. 12 were built for the French Air Force with the addition of

825-719: A drogue adapter on the refueling boom. Given Boeing model numbers 717-164 and 717-165. 11 surviving C-135Fs upgraded with CFM International F108 turbofans between 1985 and 1988. Later modified with MPRS wing pods. An airborne command post modified in 1984 to support CINCCENT . Aircraft 55-3125 was the only EC-135Y. Unlike its sister EC-135N, it was a true tanker that could also receive in-flight refueling. Pratt & Whitney TF33-PW-102. Retired to 309th AMARG at Davis-Monthan AFB, AZ. Note Italy has been reported in some sources as operating several KC-135s, however these are Boeing 707-300s converted to tanker configuration. As of 2020, 52 Stratotankers have been lost to accidents during

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900-470: A glideslope of 6 degrees or steeper and to execute missed approaches at a climb gradient sufficient to clear a 15:1 missed approach surface at sea level... A STOL runway is one which is specifically designated and marked for STOL aircraft operations, and designed and maintained to specified standards. Heavier-than-air craft that cannot take off and land vertically, but can operate within areas substantially more confined than those normally required by aircraft of

975-507: A sound pressure level of about 5% of the original level. The KC-135R's operational range is 60% greater than the KC-135E for comparable fuel offloads, providing a wider range of basing options. Upgrading the remaining KC-135Es into KC-135Rs is no longer in consideration; this would have cost approximately US$ 3 billion, $ 24 million per aircraft. According to USAF data, the KC-135 fleet had

1050-427: A total operation and support cost in fiscal year 2001 of about $ 2.2 billion (~$ 3.62 billion in 2023). The older E model aircraft averaged total costs of about $ 4.6 million per aircraft, while the R models averaged about $ 3.7 million per aircraft. Those costs include personnel, fuel, maintenance, modifications, and spare parts. In order to expand the KC-135's capabilities and improve its reliability,

1125-438: Is a function of the square of the minimum flying speed ( stall speed ), and most design effort is spent on reducing this number. For takeoff , large power/weight ratios and low drag help the plane to accelerate for flight. The landing run is minimized by strong brakes , low landing speed, thrust reversers or spoilers (less common). Overall STOL performance is set by the length of runway needed to land or take off, whichever

1200-407: Is achieved through the use of water injection on takeoff, as opposed to "wet thrust" when used to describe an afterburning engine . 670 US gallons (2,500 L) of water are injected into the engines over the course of three minutes. The water is injected into the inlet and the diffuser case in front of the combustion case. The water cools the air in the engine to increase its density; it also reduces

1275-679: Is critical, because many small, isolated communities rely on STOL aircraft as their only transportation link to the outside world for passengers or cargo; examples include many communities in the Canadian north and Alaska . Most STOL aircraft can land either on- or off-airport. Typical off-airport landing areas include snow or ice (using skis), fields or gravel riverbanks (often using special fat, low-pressure tundra tires ), and water (using floats ): these areas are often extremely short and obstructed by tall trees or hills. Wheel skis and amphibious floats combine wheels with skis or floats, allowing

1350-497: Is currently flying double its planned yearly flying hour program to meet airborne refueling requirements, and has resulted in higher than forecast usage and sustainment costs. In March 2009, the Air Force indicated that KC-135s would require additional skin replacement to allow their continued use beyond 2018. The USAF decided to replace the KC-135 fleet. However, the fleet is large and will need to be replaced gradually. Initially

1425-436: Is longer. Of equal importance to short ground run is the ability to clear obstacles, such as hills, on both take off and landing. For takeoff, large power/weight ratios and low drag result in a high rate of climb required to clear obstacles. For landing, high drag allows the aeroplane to descend steeply to the runway without building excess speed resulting in a longer ground run. Drag is increased by use of flaps (devices on

1500-448: Is significantly more unforgiving of pilot error in the receiving aircraft than conventional trailing hose arrangements; an aircraft so fitted is also incapable of refueling by the normal flying boom method until the attachment is removed. A cargo deck above the refueling system can hold a mixed load of passengers and cargo. Depending on fuel storage configuration, the KC-135 can carry up to 83,000 pounds (38,000 kg) of cargo. The KC-135

1575-674: The Air Education and Training Command (AETC). All AFRC KC-135s and most of the ANG KC-135 fleet became operationally-gained by AMC, while Alaska Air National Guard and Hawaii Air National Guard KC-135s became operationally-gained by PACAF. AMC managed 396 Stratotankers, of which the AFRC and ANG flew 243 in support of AMC's mission as of May 2018. The KC-135 is one of a few military aircraft types with over 50 years of continuous service with its original operator as of 2009. Israel

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1650-735: The KC-X program with a request for proposal (RFP). KC-X was the first phase of three acquisition programs meant to replace the KC-135 fleet. On 29 February 2008, the US Defense Department announced that it had selected the EADS / Northrop Grumman "KC-30" (to be designated the KC-45A ) over the Boeing KC-767. Boeing protested the award on 11 March 2008, citing irregularities in the competition and bid evaluation. On 18 June 2008,

1725-597: The Langley Research Center , were tested at Armstrong, using an NKC-135A tanker loaned to NASA by the Air Force. Winglets are small, nearly vertical fins installed on an aircraft's wing tips. The results of the research showed that drag was reduced and range could be increased by as much as 7 percent at cruise speeds. Winglets are now being incorporated into most new commercial and military transport/passenger jets, as well as business aviation jets. NASA also has operated several KC-135 aircraft (without

1800-690: The Mojave Airport in California. Block 40.6 allows the KC-135 to comply with global air-traffic management . The latest block upgrade to the KC-135, the Block 45 program, is online with the first 45 upgraded aircraft delivered by January 2017. Block 45 adds a new glass cockpit digital display, radio altimeter, digital autopilot, digital flight director and computer updates. The original, no longer procurable, analog instruments, including all engine gauges, were replaced. Rockwell Collins again supplied

1875-753: The Pratt & Whitney JT8D-17 widely used on the Boeing 727 and Douglas DC-9 . The YC-15 borrowed components from other McDonnell Douglas aircraft, with its nose gear coming from the Douglas DC-8 and the nose section and cockpit being derived from the Douglas DC-10 . Parts borrowed from other aircraft included the Universal Aerial Refueling Receptacle Slipway Installation (UARRSI), taken from

1950-626: The United States that were used for scheduled passenger airline operations but are now no longer in existence. Cruise -efficient short takeoff and landing (CESTOL), is an aircraft with both very short runway requirements and high cruise speeds (greater than Mach 0.8). Many different definitions of STOL have been used by different authorities and nations at various times and for a myriad of regulatory and military purposes. Some accepted definitions of STOL include: short takeoff and landing: ( DOD / NATO ) The ability of an aircraft to clear

2025-670: The de Havilland Canada Dash-7 , are designed for use on prepared airstrips; likewise, many STOL aircraft are taildraggers , though there are exceptions like the PAC P-750 XSTOL , the Quest Kodiak , the de Havilland Canada DHC-6 Twin Otter and the Peterson 260SE . Autogyros also have STOL capability, needing a short ground roll to get airborne, but capable of a near-zero ground roll when landing. Runway length requirement

2100-1003: The 309th AMARG at Davis-Monthan AFB by September 2009 and replaced with R models. Test-configured KC-135E. 55-3132 NKC-135E "Big Crow I" & 63-8050 NKC-135B "Big Crow II" used as airborne targets for the Boeing YAL-1 Airborne Laser carrier. KC-135As modified to carry JP-7 fuel necessary for the SR-71 Blackbird, 56 modified, survivors to KC-135T. 4 JC/KC-135As converted to Rivet Stand (Later Rivet Quick ) configuration for reconnaissance and evaluation of above ground nuclear test (55-3121, 59–1465, 59–1514, 58–0126; 58-0126 replaced 59-1465 after it crashed in 1967). These aircraft were powered by Pratt & Whitney J57 engines and were based at Offutt AFB , Nebraska . KC-135As and some KC-135Es re-engined with CFM56 engines, more than 417 converted Receiver-capable KC-135R Stratotanker; eight modified with either

2175-430: The 707, and is structurally quite different from the civilian airliner. Boeing gave the future KC-135 tanker the initial designation Model 717. In 1954 USAF's Strategic Air Command (SAC) held a competition for a jet-powered aerial refueling tanker. Lockheed Corporation 's tanker version of the proposed Lockheed L-193 airliner with rear fuselage-mounted engines was declared the winner in 1955. Since Boeing's proposal

2250-592: The 707. In 1954, the USAF placed an initial order for 29 KC-135As, the first of an eventual 820 of all variants of the basic C-135 family. The first aircraft flew in August 1956 and the initial production Stratotanker was delivered to Castle Air Force Base , California , in June 1957. The last KC-135 was delivered to the USAF in 1965. Developed in the early 1950s, the basic airframe is characterized by 35-degree aft swept wings and tail , four underwing-mounted engine pods,

2325-463: The Air Force, only a few KC-135s would reach these limits by 2040, when some aircraft would be about 80 years old. A later 2005 Air Force study estimated that KC-135Es upgraded to the R standard could remain in use until 2030. In 2006, the KC-135E fleet was flying an annual average of 350 hours per aircraft and the KC-135R fleet was flying an annual average of 710 hours per aircraft. The KC-135 fleet

McDonnell Douglas YC-15 - Misplaced Pages Continue

2400-703: The C-X Task Force formed to develop the required strategic aircraft with tactical capability. The C-X program selected a proposal for an enlarged and upgraded YC-15 that was later developed into the C-17 Globemaster III . The Lockheed C-130 Hercules would be further improved into the C-130J and remains in service. After the flight test program, the two aircraft were stored at the AMARC , located at Davis-Monthan Air Force Base . One aircraft (72-1875)

2475-627: The KC-135 Stratotanker in service with Regular Air Force SAC units from 1957 through 1992 and with SAC-gained ANG and AFRES units from 1975 through 1992. Following a major USAF reorganization that resulted in the inactivation of SAC in 1992, most KC-135s were reassigned to the newly created AMC. While AMC gained the preponderance of the aerial refueling mission, a small number of KC-135s were also assigned directly to United States Air Forces in Europe (USAFE), Pacific Air Forces (PACAF) and

2550-412: The KC-135's wings. The pods allow refueling of U.S. Navy, U.S. Marine Corps and most NATO tactical jet aircraft while keeping the tail-mounted refueling boom. The pods themselves are Flight Refueling Limited MK.32B model pods, and refuel via the probe and drogue method common to Navy/Marine Corps tactical jets, rather than the primary " flying boom " method used by Air Force fixed-wing aircraft. This allows

2625-655: The KC-135Q model received the CFM56 engines, it was redesignated the KC-135T model, which was capable of separating the main body tanks from the wing tanks where the KC-135 draws its engine fuel. The only external difference between a KC-135R and a KC-135T is the presence of a clear window on the underside of the empennage of the KC-135T where a remote controlled searchlight is mounted. It also has two ground refueling ports, located in each rear wheel well so ground crews can fuel both

2700-452: The KC-97, the mixed gasoline/kerosene fuel system was clearly not desirable and it was obvious that a jet-powered tanker aircraft would be the next development, having a single type of fuel for both its own engines and for passing to receiver aircraft. The 230 mph (370 km/h) cruise speed of the slower, piston-engined KC-97 was also a serious issue, as using it as an aerial tanker forced

2775-469: The RC-135As on-board photo-mapping systems. Later re-engined with Pratt & Whitney TF33 engines and a cockpit update to KC-135E standards in 1990 and were retired to the 309th AMARG at Davis-Monthan AFB , AZ in 2007. Air National Guard and Air Force Reserve KC-135As re-engined with Pratt & Whitney TF33-PW-102 engines from retired 707 airliners (161 modified). All E model aircraft were retired to

2850-759: The US Government Accountability Office sustained Boeing's protest of the selection of the Northrop Grumman/EADS's tanker. In February 2010, the US Air Force restarted the KC-X competition with the release of a revised request for proposal (RFP). After evaluating bids, the USAF selected Boeing's 767-based tanker design, with the military designation KC-46 , as a replacement in February 2011. The first KC-46A Pegasus

2925-593: The USAF from formally retiring them. The final KC-135E, tail number 56-3630 , was delivered by the 101st Air Refueling Wing to the 309th Aerospace Maintenance and Regeneration Group (AMARG) at Davis–Monthan Air Force Base in September 2009. The second modification program retrofitted 500 aircraft with new CFM International CFM56 (military designation: F108) high-bypass turbofan engines produced by General Electric and Safran . The CFM56 engine produces approximately 22,500 lbf (100 kN) of thrust, nearly

3000-499: The USAF in 1957; it is one of nine military fixed-wing aircraft with over 60 years of continuous service with its original operator. The KC-135 was supplemented by the larger McDonnell Douglas KC-10 Extender . Studies have concluded that many of the aircraft could be flown until 2030, although maintenance costs have greatly increased. The KC-135 is to be partially replaced by the Boeing KC-46 Pegasus . Starting in 1950

3075-563: The USAF operated the world's first production aerial tanker, the Boeing KC-97 Stratofreighter , a gasoline fueled piston-engined Boeing Stratocruiser (USAF designation C-97 Stratofreighter ) with a Boeing-developed flying boom and extra kerosene (jet fuel) tanks feeding the boom. The Stratocruiser airliner itself was developed from the Boeing B-29 Superfortress bomber after World War II . In

McDonnell Douglas YC-15 - Misplaced Pages Continue

3150-496: The YC-15 flew short landing approaches at only 87 kn at a 6 degree glide slope yielding a sink rate of 15.4 feet per second, compared with normal approaches that were made at about 127 kn with a typical 8-12 feet per second sink rate. For short landings, the touch down aim-point was only about 300 feet from the runway end. Pilots of the YC-15 tested both no-flare and with-flare landing techniques in STOL mode. Because of slow actuation of

3225-586: The YC-15's basic design would be used to form the successful McDonnell Douglas (later Boeing) C-17 Globemaster III . In 1968, the USAF started work on a series of prototype proposals, which would lead to both the AMST project and the Light Weight Fighter . The official Request for proposal (RFP) was issued in January 1972, asking for operations into a 2,000-foot (610 m) semi-prepared field with

3300-583: The aircraft has undergone a number of avionics upgrades. Among these was the Pacer-CRAG program (compass, radar and GPS) which ran from 1999 to 2002 and modified all the aircraft in the inventory to eliminate the Navigator position from the flight crew. The fuel management system was also replaced. The program development was done by Rockwell Collins in Iowa and installation was performed by BAE Systems at

3375-402: The aircraft meets any accepted definition. Boeing KC-135 The Boeing KC-135 Stratotanker is an American military aerial refueling tanker aircraft that was developed from the Boeing 367-80 prototype, alongside the Boeing 707 airliner. It has a narrower fuselage and is shorter than the 707. Boeing gave the aircraft the internal designation of Model 717 (number later assigned to

3450-882: The aircraft was deemed too expensive to repair and was stored at Palmdale. In 2008, the aircraft was moved by road to Edwards AFB, where it is now on display at the Air Force Flight Test Center Museum's "Century Circle" display area, just outside the base's west gate. The other airframe (72–1876), which had remained on Celebrity Row at the AMARC for many years, was destroyed in place in April 2012. Data from The Observer's Book of Aircraft. General characteristics Performance Related development Aircraft of comparable role, configuration, and era Related lists STOL Many fixed-wing STOL aircraft are bush planes , though some, like

3525-775: The aircraft, including the RC-135 Rivet Joint and EC-135 Looking Glass aircraft were operated by SAC from 1963 through 1992, when they were reassigned to the Air Combat Command (ACC). The USAF EC-135 Looking Glass was subsequently replaced in its role by the U.S. Navy E-6 Mercury aircraft, a new build airframe based on the Boeing 707-320B. All KC-135s were originally equipped with Pratt & Whitney J57-P-59W turbojet engines, which produced 10,000 lbf (44 kN) of thrust dry, and approximately 13,000 lbf (58 kN) of thrust wet . Wet thrust

3600-543: The body tanks and wing tanks separately. Eight KC-135R aircraft are receiver-capable tankers, commonly referred to as KC-135R(RT). All eight aircraft were with the 22d Air Refueling Wing at McConnell AFB , Kansas, in 1994. They are primarily used for force extension and Special Operations missions, and are crewed by highly qualified receiver capable crews. If not used for the receiver mission, these aircraft can be flown just like any other KC-135R. The Multi-point Refueling Systems (MPRS) modification adds refueling pods to

3675-471: The choice of landing on snow/water or a prepared runway. A number of aircraft modification companies offer STOL kits for improving short-field performance. A STOLport is an airport designed with STOL operations in mind, normally having a short single runway. STOLports are not common but can be found, for example, at London City Airport in London , United Kingdom . There were also several STOLports in

3750-511: The first batch of replacement planes was to be an air tanker version of the Boeing 767 , leased from Boeing . In 2003, this was changed to contract where the Air Force would purchase 80 KC-767 aircraft and lease 20 more. In December 2003, the Pentagon froze the contract and in January 2006, the KC-767 contract was canceled. This move followed public revelations of corruption in how the contract

3825-454: The flight test program, a "refanned" Pratt & Whitney JT8D-209 was tested in No. 1 nacelle of 72–1876, and a CFM International CFM56 was tested in the No. 1 nacelle of 72–1875. In addition, a new wing with increased chord and span was flown on 72–1875. The YC-15 met specifications under most, but not all, conditions. It was a very good STOL plane for its size. At a gross weight of 149,300lbs,

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3900-574: The jet exhaust downwards, while the rest of the exhaust passed through the flap and then followed the downward curve due to the Coandă effect . Although the effects had been studied for some time at NASA, along with similar concepts, until the introduction of the turbofan the hot and concentrated exhaust of existing engines made the system difficult to use. By the time of the AMST project, engines had changed dramatically and now provided larger volumes of less-concentrated and much cooler air. The YC-15 prototype

3975-498: The late 1970s and early 1980s. The modified tanker, designated the KC-135E, was 14% more fuel-efficient than the KC-135A and could offload 20% more fuel on long-duration flights. Only the KC-135E aircraft were equipped with thrust reversers for aborted takeoffs and shorter landing roll-outs. The KC-135E fleet has since either been retrofitted as the R-model configuration or placed into long-term storage ("XJ"), as Congress has prevented

4050-534: The major avionic modules, with modification done at Tinker AFB . The KC-135Q variant was modified to carry JP-7 fuel necessary for the Lockheed SR-71 Blackbird by separating the JP-7 from the KC-135's own fuel supply (the body tanks carrying JP-7, and the wing tanks carrying JP-4 or JP-8 ). The tanker also had special fuel systems for moving the different fuels between different tanks. When

4125-554: The mission, the Navy and Marine Corps not having fitted their aircraft with flying boom receptacles since the USAF boom system was impractical for aircraft carrier operations. Crews also helped to bring in damaged aircraft which could sometimes fly while being fed by fuel to a landing site or to ditch over the water (specifically those with punctured fuel tanks). KC-135s continued their tactical support role in later conflicts such as Operation Desert Storm and current aerial strategy. SAC had

4200-598: The model number 717-166. All four RC-135As ( Pacer Swan ) were modified to partial KC-135A configuration in 1979. The four aircraft (serial numbers 63-8058, 63-8059, 63-8060 and 63-8061 ) were given a unique designation KC-135D as they differed from the KC-135A in that they were built with a flight engineer's position on the flight deck. The flight engineer's position was removed when the aircraft were modified to KC-135 standards but they retained their electrically powered wing flap secondary (emergency) drive mechanism and second air conditioning pack which had been used to cool

4275-411: The newer jet-powered military aircraft to slow down to mate with the tanker's boom. Like its sibling, the commercial Boeing 707 jet airliner , the KC-135 was derived from the Boeing 367-80 jet transport "proof of concept" demonstrator, which was commonly called the "Dash-80". The KC-135 is similar in appearance to the 707, but has a narrower fuselage and is shorter than the 707. The KC-135 predates

4350-462: The same size. Derived from short takeoff and landing aircraft. short takeoff and landing aircraft (STOL), heavier-than-air craft, capable of rising from and descending to the ground with only a short length of runway, but incapable of doing so vertically. The precise definition of an STOL aircraft has not been universally agreed upon. However, it has been tentatively defined as an aircraft that upon taking off needs only 1,000 ft (305 m) of runway to clear

4425-959: The tanker equipment installed) as their famed Vomit Comet zero-gravity simulator aircraft. The longest-serving (1973 to 1995) version was KC-135A, AF Ser. No. 59-1481 , named Weightless Wonder IV and registered as N930NA. Between 1993 and 2003, the amount of KC-135 depot maintenance work doubled, and the overhaul cost per aircraft tripled. In 1996, it cost $ 8,400 per flight hour for the KC-135, and in 2002 this had grown to $ 11,000. The Air Force's 15-year estimates project further significant cost growth through fiscal year 2017. KC-135 fleet operations and support costs were estimated to grow from about $ 2.2 billion in fiscal year 2003 to $ 5.1 billion (2003 dollars) in fiscal year 2017, an increase of over 130 percent, which represented an annual operating cost growth rate of about 6.2 percent. The USAF projected that E and R models have lifetime flying hour limits of 36,000 and 39,000 hours, respectively. According to

4500-625: The tanker to refuel two receivers at the same time, which increases throughput compared to the boom drogue adapter. A number of KC-135A and KC-135B aircraft have been modified to EC-135, RC-135 and OC-135 configurations for use in several different roles (although these could also be considered variants of the C-135 Stratolifter family). The KC-135R has four turbofan engines, mounted under 35-degree swept wings, which power it to takeoffs at gross weights up to 322,500 pounds (146,300 kg). Nearly all internal fuel can be pumped through

4575-455: The tanker's flying boom , the KC-135's primary fuel transfer method. A boom operator stationed in the rear of the aircraft controls the boom while lying prone, viewing through a window at the bottom of the tail. Both the flying boom and operator's station are similar to those of the previous KC-97. A special shuttlecock-shaped drogue, attached to and trailing behind the flying boom, may be used to refuel aircraft fitted with probes. This apparatus

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4650-601: The thrust reversers, testing at Edwards AFB showed the plane was unable to consistently stop in “hot-and-high” conditions in the required 2000 feet. However, the seeds of the AMST program's demise had already been sown. In March 1976, the Air Force Chief of Staff, Gen. David C. Jones , asked the Air Force Systems Command to see if it was possible to use a single model of the AMST for both strategic and tactical airlift roles, or alternatively, if it

4725-537: The turbine gas temperature, which is a primary limitation on many jet engines. This allows the use of more fuel for proper combustion and creates more thrust for short periods of time, similar in concept to " War Emergency Power " in a piston-engined aircraft. In the 1980s, the first modification program retrofitted 157 Air Force Reserve (AFRES) and Air National Guard (ANG) tankers with the Pratt & Whitney TF33-PW-102 turbofan engines from 707 airliners retired in

4800-433: The wings) and by a forward slip (causing the aeroplane to fly somewhat sideways through the air to increase drag). Normally, a STOL aircraft will have a large wing for its weight. These wings often use aerodynamic devices like flaps, slots , slats , and vortex generators . Typically, designing an aircraft for excellent STOL performance reduces maximum speed, but does not reduce payload lifting ability. The payload

4875-470: Was already flying, the KC-135 could be delivered two years earlier and Air Force Secretary Harold E. Talbott ordered 250 KC-135 tankers until Lockheed's design could be manufactured. In the end, orders for the Lockheed tanker were dropped rather than supporting two tanker designs. Lockheed never produced its jet airliner, while Boeing would eventually dominate the market with a family of airliners based on

4950-459: Was awarded, as well as controversy regarding the original leasing rather than outright purchase agreement. The then Secretary of Defense Rumsfeld stated that that move would in no way impair the Air Force's ability to deliver the mission of the KC-767, which would be accomplished by implementing continuing upgrades to the KC-135 and KC-10 Extender fleet. In January 2007, the U.S. Air Force launched

5025-686: Was delivered to the U.S. Air Force on 10 January 2019. Two export users of the KC-135, the French Air and Space Force and the Republic of Singapore Air Force took deliveries of Airbus A330 MRTTs as replacements for their Stratotankers. Original production version powered by four Pratt & Whitney J57s , 732 built. Given the Boeing model numbers 717-100A, 717-146 and 717-148. Test-configured KC-135A. Airborne command post version equipped with turbofan engines, 17 built. Provided with in-flight refueling capability and redesignated EC-135C. Given

5100-640: Was designated YC-15. McDonnell Douglas's design incorporated a supercritical wing , the result of NASA research carried out by the already famous Richard Whitcomb . This wing design dramatically lowers transonic wave drag by as much as 30% compared to more conventional profiles, while at the same time offering excellent low-speed lift. Most contemporary aircraft used swept wings to lower wave drag, but this led to poor low-speed handling, which made them unsuitable for STOL operations. The design team also chose to use externally blown flaps to increase lift. This system uses double-slotted flaps to direct part of

5175-675: Was initially purchased to support SAC bombers, but by the late 1960s, in the Southeast Asia theater, the KC-135 Stratotanker's ability as a force multiplier came to the fore. Midair refueling of F-105 and F-4 fighter-bombers as well as B-52 bombers brought far-flung bombing targets within reach, and allowed fighter missions to spend hours at the front, rather than a few minutes, which was usual due to their limited fuel reserves and high fuel consumption. KC-135 crews refueled both USAF and Navy/ Marine Corps aircraft; though they would have to change to probe and drogue adapters depending upon

5250-671: Was offered KC-135s again in 2013, after turning down the aging aircraft twice due to expense of keeping them flying. The IAF again rejected the offered KC-135Es, but said that it would consider up to a dozen of the newer KC-135Rs. Besides its primary role as an inflight aircraft refueler, the KC-135, designated NKC-135, has assisted in several research projects at the NASA Armstrong Flight Research Center at Edwards Air Force Base , California. One such project occurred between 1979 and 1980 when special wingtip " winglets ", developed by Richard Whitcomb of

5325-471: Was on 26 August 1975. The second prototype followed in December. They were tested for some time at McDonnell Douglas as the Boeing entry was not ready until almost a year later. In November 1976, both designs were transferred to Edwards Air Force Base for head-to-head testing, including lifting heavy loads like tanks and artillery from dirt airfields at Graham Ranch, off the end of Runway 22. In Phase II of

5400-475: Was possible to develop non-STOL derivatives of the AMST for the strategic airlift role. This led to a series of studies that basically stated that such a modification was not easy, and would require major changes to either design to produce a much larger aircraft. The increasing importance of the strategic vs. tactical mission eventually led to the end of the AMST program in December 1979. Then, in November 1979,

5475-490: Was subsequently moved to the nearby Pima Air & Space Museum in 1981, but was returned to flying status by McDonnell Douglas in 1996; it was first reflown on 11 April 1997. On 16 April 1997, the aircraft was ferried to Long Beach, California to support the C-17 program. On 11 July 1998, the aircraft suffered a massive failure of the No. 1 engine during flight and made an emergency landing at Palmdale, California. On inspection,

5550-509: Was the first aircraft to offer pilots a heads up display. It was especially designed to help with short field landings, showing the pilot the horizon, flight path scale, airspeed indexer and touchdown point. Two YC-15s were built, one with a wingspan of 110 feet (34 m) (#72-1876) and one of 132 feet (40 m) (#72-1875). Both were 124 feet (38 m) long and powered by four Pratt & Whitney JT8D-17 engines, each with 15,500 pounds-force (69,000  N ) of thrust. The first flight

5625-404: Was the first jet powered aircraft to use externally blown flaps. For later prototypes, there were several modifications including a computer on the YC-15 was devised that would calculate the best flap angle for various flight conditions given the current gross weight. Together these modifications offered a reduction in approach speed of 10 kn. For the YC-15, four engines were used, versions of

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