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88-509: The basic design had a rectangular wing spanning almost 500 feet (150 m), was powered by 12 Pratt & Whitney JT9D engines, and had 56 wheels in the main landing gear. A total of 2,300,000 pounds (1,000,000 kg) of cargo was carried in two under-wing pods and fuselage. The RC-1 would have been roughly twice the size and mass of the Antonov An-225 Mriya , the largest aircraft built, but would have carried about five times

176-501: A ski-jump on take-off is subjected to loads of 0.5g which also last for much longer than a landing impact. Helicopters may have a deck-lock harpoon to anchor them to the deck. Some aircraft have a requirement to use the landing-gear as a speed brake. Flexible mounting of the stowed main landing-gear bogies on the Tupolev Tu-22 R raised the aircraft flutter speed to 550 kn (1,020 km/h). The bogies oscillated within

264-428: A tripod effect. Some unusual landing gear have been evaluated experimentally. These include: no landing gear (to save weight), made possible by operating from a catapult cradle and flexible landing deck: air cushion (to enable operation over a wide range of ground obstacles and water/snow/ice); tracked (to reduce runway loading). For launch vehicles and spacecraft landers , the landing gear usually only supports

352-414: A "boat" hull/floats and retractable wheels, which allow it to operate from land or water. Beaching gear is detachable wheeled landing gear that allows a non-amphibious floatplane or flying boat to be maneuvered on land. It is used for aircraft maintenance and storage and is either carried in the aircraft or kept at a slipway. Beaching gear may consist of individual detachable wheels or a cradle that supports

440-442: A 10 in (25 cm) thick flexible asphalt pavement . The 210,000 lb (95 t) Boeing 727 -200 with four tires on two legs main landing gears required a 20 in (51 cm) thick pavement. The thickness rose to 25 in (64 cm) for a McDonnell Douglas DC-10 -10 with 443,000 lb (201 t) supported on eight wheels on two legs. The heavier, 558,000 lb (253 t), DC-10-30/40 were able to operate from

528-474: A 90° angle during the rearwards-retraction sequence to allow the main wheel to rest "flat" above the lower end of the main gear strut, or flush within the wing or engine nacelles, when fully retracted. Examples are the Curtiss P-40 , Vought F4U Corsair , Grumman F6F Hellcat , Messerschmitt Me 210 and Junkers Ju 88 . The Aero Commander family of twin-engined business aircraft also shares this feature on

616-476: A forward and aft position. The forward position was used for take-off to give a longer lever-arm for pitch control and greater nose-up attitude. The aft position was used to reduce landing bounce and reduce risk of tip-back during ground handling. The tandem or bicycle layout is used on the Hawker Siddeley Harrier, which has two main-wheels behind a single nose-wheel under the fuselage and

704-585: A higher sink-rate requirement because the aircraft are flown onto the deck with no landing flare . Other features are related to catapult take-off requirements for specific aircraft. For example, the Blackburn Buccaneer was pulled down onto its tail-skid to set the required nose-up attitude. The naval McDonnell Douglas F-4 Phantom II in UK service needed an extending nosewheel leg to set the wing attitude at launch. The landing gear for an aircraft using

792-474: A higher sink-rate requirement if a carrier-type, no-flare landing technique has to be adopted to reduce touchdown scatter. For example, the Saab 37 Viggen , with landing gear designed for a 5m/sec impact, could use a carrier-type landing and HUD to reduce its scatter from 300 m to 100m. The de Havilland Canada DHC-4 Caribou used long-stroke legs to land from a steep approach with no float. A flying boat has

880-489: A light aircraft, an emergency extension system is always available. This may be a manually operated crank or pump, or a mechanical free-fall mechanism which disengages the uplocks and allows the landing gear to fall under gravity. Aircraft landing gear includes wheels equipped with solid shock absorbers on light planes, and air/oil oleo struts on larger aircraft. As aircraft weights have increased more wheels have been added and runway thickness has increased to keep within

968-403: A lower fuselage with the shape of a boat hull giving it buoyancy. Wing-mounted floats or stubby wing-like sponsons are added for stability. Sponsons are attached to the lower sides of the fuselage. A floatplane has two or three streamlined floats. Amphibious floats have retractable wheels for land operation. An amphibious aircraft or amphibian usually has two distinct landing gears, namely

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1056-405: A new rail line, but it would also replace Churchill as a useful commercial port. The RC-1 would have eased these concerns; building an airport at Churchill was far less expensive than a new port and railway to connect it. The Project also considered unrelated projects, including huge fish farms in the prairies fed from enormous underground warm-water aquifers, and year-round "vegetable factories" in

1144-537: A nosewheel) chassis. Landing is done on skids or similar simple devices (fixed or retractable). The SNCASE Baroudeur used this arrangement. Historical examples include the "dolly"-using Messerschmitt Me 163 Komet rocket fighter, the Messerschmitt Me 321 Gigant troop glider, and the first eight "trolley"-using prototypes of the Arado Ar 234 jet reconnaissance bomber. The main disadvantage to using

1232-457: A similar arrangement, except that the fore and aft gears each have two twin-wheel units side by side. Quadricycle gear is similar to bicycle but with two sets of wheels displaced laterally in the fore and aft positions. Raymer classifies the B-52 gear as quadricycle. The experimental Fairchild XC-120 Packplane had quadricycle gear located in the engine nacelles to allow unrestricted access beneath

1320-520: A smaller wheel near the tip of each wing. On second generation Harriers, the wing is extended past the outrigger wheels to allow greater wing-mounted munition loads to be carried, or to permit wing-tip extensions to be bolted on for ferry flights. A tandem layout was evaluated by Martin using a specially-modified Martin B-26 Marauder (the XB-26H) to evaluate its use on Martin's first jet bomber,

1408-557: A tricycle undercarriage to prevent damage to the underside of the fuselage if over-rotation occurs on take-off leading to a tail strike . Aircraft with tail-strike protection include the B-29 Superfortress , Boeing 727 trijet and Concorde . Some aircraft with retractable conventional landing gear have a fixed tailwheel. Hoerner estimated the drag of the Bf 109 fixed tailwheel and compared it with that of other protrusions such as

1496-412: Is also unique in that all four pairs of main wheels can be steered. This allows the landing gear to line up with the runway and thus makes crosswind landings easier (using a technique called crab landing ). Since tandem aircraft cannot rotate for takeoff, the forward gear must be long enough to give the wings the correct angle of attack during takeoff. During landing, the forward gear must not touch

1584-465: Is required to reduce the impact with the surface of the water. A vee bottom parts the water and chines deflect the spray to prevent it damaging vulnerable parts of the aircraft. Additional spray control may be needed using spray strips or inverted gutters. A step is added to the hull, just behind the center of gravity, to stop water clinging to the afterbody so the aircraft can accelerate to flying speed. The step allows air, known as ventilation air, to break

1672-405: Is the most common, with skis or floats needed to operate from snow/ice/water and skids for vertical operation on land. Retractable undercarriages fold away during flight, which reduces drag , allowing for faster airspeeds . Landing gear must be strong enough to support the aircraft and its design affects the weight, balance and performance. It often comprises three wheels, or wheel-sets, giving

1760-578: Is used for taxiing , takeoff or landing . For aircraft, it is generally needed for all three of these. It was also formerly called alighting gear by some manufacturers, such as the Glenn L. Martin Company . For aircraft, Stinton makes the terminology distinction undercarriage (British) = landing gear (US) . For aircraft, the landing gear supports the craft when it is not flying, allowing it to take off, land, and taxi without damage. Wheeled landing gear

1848-642: The Arctic Ocean and Hudson's Bay year-round, and a new northern deepwater port to support these ships, referred to as "Northport". This led to considerable concern in the town of Churchill, Manitoba , at that time the only major port on Hudson's Bay. Churchill was connected south by the Hudson Bay Railway , but its port was too shallow to handle the deep-hulled icebreakers being considered. Northport, considered at either Chesterfield Inlet or even Repulse Bay , would have connected to Churchill via

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1936-705: The Beriev A-40 Hydro flaps were used on the Martin Marlin and Martin SeaMaster . Hydroflaps, submerged at the rear of the afterbody, act as a speed brake or differentially as a rudder. A fixed fin, known as a skeg , has been used for directional stability. A skeg, was added to the second step on the Kawanishi H8K flying boat hull. High speed impacts in rough water between the hull and wave flanks may be reduced using hydro-skis which hold

2024-667: The Boeing 747 , flying long multi-hour flights from the oil fields in Alaska to California. However, the sortie rates of commercial aircraft are based on customer preferences on what times they want to fly, not the actual ability of the aircraft. Assuming much shorter routes and 24-hour operation, sortie rates on the order of 18 to 20 flights a day seemed possible. This greatly reduced the number of aircraft that were needed to provide any particular level of service. With these two concepts, it appeared that existing cargo conversions of aircraft like

2112-697: The Boeing 747 . It subsequently powered the Boeing 767 , Airbus A300 and Airbus A310 , and McDonnell Douglas DC-10 . The enhanced JT9D-7R4 was introduced in September 1982 and was approved for 180-minute ETOPS for twinjets in June 1985. By 2020, the JT9D had flown more than 169 million hours. Production ceased in 1990, to be replaced by the new PW4000 . The JT9D was developed from the STF200/JTF14 demonstrator engines. The JTF14 engine had been proposed for

2200-677: The C-5 Galaxy program but the production contract was awarded to the General Electric TF39 . The engine's first test run took place in a test rig at East Hartford, Connecticut, with the engine's first flight in June 1968 mounted on a Boeing B-52 E which served as a JT9D flying testbed . In 1968, its unit cost was $ 800,000, $ 7 million today. The JT9D introduced advanced technologies in structures, aerodynamics, and materials, which included titanium alloys and nickel alloys , to improve fuel efficiency and reliability compared to

2288-561: The Martin Marlin , the Martin M-270, was tested with a new hull with a greater length/beam ratio of 15 obtained by adding 6 feet to both the nose and tail. Rough-sea capability can be improved with lower take-off and landing speeds because impacts with waves are reduced. The Shin Meiwa US-1A is a STOL amphibian with blown flaps and all control surfaces. The ability to land and take-off at relatively low speeds of about 45 knots and

2376-702: The Martin XB-48 . This configuration proved so manoeuvrable that it was also selected for the B-47 Stratojet . It was also used on the U-2, Myasishchev M-4 , Yakovlev Yak-25 , Yak-28 and Sud Aviation Vautour . A variation of the multi tandem layout is also used on the B-52 Stratofortress which has four main wheel bogies (two forward and two aft) underneath the fuselage and a small outrigger wheel supporting each wing-tip. The B-52's landing gear

2464-500: The Pratt & Whitney JT3D earlier turbofan. The engine featured a single-stage fan, a three-stage low-pressure compressor, and an eleven-stage high-pressure compressor coupled to a two-stage high-pressure turbine and four-stage low-pressure turbine. The JT9D-3, the earliest certified version of the engine, weighed 8,470 lb (3,840 kg) and produced 43,500 lbf (193 kN) thrust. Pratt & Whitney faced difficulties with

2552-418: The landing gear , the total amount of cargo that could be carried was dramatically increased. This allowed the gear to be placed on the wings as on traditional designs, instead of the complex fuselage-mounted systems normally found on heavy lifters. This led to a further modification by placing two sets of gear on either side of each cargo pod, for a total of eight sets of main landing gear, further spreading out

2640-547: The $ 15 million required for a full design study. History, in the form of the 1973 oil crisis , ended these plans. The approximate doubling of jet fuel prices during the period from 1973 to 1974 rendered the RC-1 no longer competitive with a pipeline. No further work on the design appears to have been carried out. The Alaskan fields would ultimately be served by the Trans-Alaska Pipeline System . The RC-1

2728-403: The 747 would result in airlift prices just below the current price of crude. This was not particularly practical, but given the great improvements over initial concepts, further studies followed. The first of these considered adaptations of the existing 747F freighters, removing the jet fuel from the wings due to the short range (relying instead on tanks in the fuselage and tail). With the load on

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2816-638: The Arctic. With these changes in place, Boeing was once again ready to present the new RC-1 design to the developers of the Prudhoe Bay oil fields . By this time several successful attempts had been made by the SS ; Manhattan to force transit of the Northwest Passage in 1969 and 1970, but the "icebreaker tanker" was considered too risky to consider for continuous operations. In 1972 Boeing

2904-643: The Great Plains Project to study economic development of the Canadian west and north. The Project was tasked with considering only "big picture" developments, ones that were just within the capabilities of existing technology. As part of this project, the known mineral and potential oil and gas deposits in the Canadian Arctic Archipelago were considered for development. Shipping the products proved to be an enormous problem;

2992-437: The Great Plains Project, was the use of methane for fuel instead of jet fuel. Due to aerodynamic control considerations, the fuselage of the RC-1 had to be very large, yet carried almost nothing. This left enormous room for fuel tankage, and the use of methane, hydrogen, or other lightweight fuels was a natural consideration. As the Canadian group was also interested in using the RC-1 to haul liquified natural gas , using this as

3080-553: The JT9D design during the Boeing 747 test program. Engine failures during the flight test program resulted in thirty aircraft being parked outside the factory with concrete blocks hanging from the pylons, awaiting redesigned engines. Boeing and Pratt & Whitney worked together in 1969 to solve the problem. The trouble was traced to ovalization, in which stresses during takeoff caused the engine casing to deform into an oval shape resulting in rubbing of high-pressure turbine blade tips. This

3168-416: The aircraft can be landed in a satisfactory manner in a range of failure scenarios. The Boeing 747 was given four separate and independent hydraulic systems (when previous airliners had two) and four main landing gear posts (when previous airliners had two). Safe landing would be possible if two main gear legs were torn off provided they were on opposite sides of the fuselage. In the case of power failure in

3256-414: The aircraft cost, but 20% of the airframe direct maintenance cost. A suitably-designed wheel can support 30 t (66,000 lb), tolerate a ground speed of 300 km/h and roll a distance of 500,000 km (310,000 mi) ; it has a 20,000 hours time between overhaul and a 60,000 hours or 20 year life time. Wheeled undercarriages normally come in two types: The taildragger arrangement

3344-436: The aircraft flew the return flight, taking a set of now-emptied pods from a previous aircraft with it. As they explored the concept, it became clear that the offline loading greatly improved turnaround times for any cargo, including oil. Further, custom pods allowed them to ship any sort of cargo on the same aircraft. This led to the question as to where these pods should be located. An obvious solution would be to load them into

3432-418: The aircraft for mating. To achieve the required sortie rate needed to make the "flying pipeline" concept work, Boeing designed an airport around the aircraft. This featured three parallel runways that would operate at the same time. Aircraft landed on the two outer runways, and then taxied along large operational aprons at either end of the runways. Here they dropped their cargo pods and picked up empty ones for

3520-444: The aircraft to return to for another load more rapidly than if it flew all the way to California, meaning that a single aircraft could deliver more cargo in a given time. This had been noticed in the earlier studies, but the full impact had not been appreciated. This led naturally to the second issue, involving the sortie rate of the aircraft. In the initial calculations they had assumed similar sortie rates as commercial aircraft like

3608-405: The aircraft's huge fuselage. However, this would require the nose or tail to open, adding some complexity. It was noticed early on that it could be loaded much faster if the cargo was placed under the wings instead; the cargo containers could be driven up to either side of the aircraft at the same time. As soon as this was considered another major advantage became clear; by locating the pods closer to

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3696-421: The airlift concept. It was noticed early on that two important factors had not been fully considered earlier. One was that an aircraft flying from Alaska to California would be flying right over some of the best developed shipping lanes available. By offloading as early as possible to some other mode of transport—tankers or pipelines—the amount of fuel burned would be greatly reduced. More importantly, this freed

3784-470: The airstream, it is called a semi-retractable gear. Most retractable gear is hydraulically operated, though some is electrically operated or even manually operated on very light aircraft. The landing gear is stowed in a compartment called a wheel well. Pilots confirming that their landing gear is down and locked refer to "three greens" or "three in the green.", a reference to the electrical indicator lights (or painted panels of mechanical indicator units) from

3872-576: The ends of the two outer runways for takeoff. This would reduce sortie rates. Likewise, at the loading end of the route, the aircraft would land downwind, load, and takeoff upwind. Empty weight was 985,000 pounds (447,000 kg), almost twice that of the Antonov An-225 , the largest and heaviest aircraft to be built, at 285,000 kilograms (628,000 lb). Data from Taylor, 1973 General characteristics Performance Pratt %26 Whitney JT9D The Pratt & Whitney JT9D engine

3960-410: The entire aircraft. In the former case, the beaching gear is manually attached or detached with the aircraft in the water; in the latter case, the aircraft is maneuvered onto the cradle. Helicopters are able to land on water using floats or a hull and floats. For take-off a step and planing bottom are required to lift from the floating position to planing on the surface. For landing a cleaving action

4048-451: The era. The fuselage was large and roughly the size of a wide-body airliner (although relative to the length, it appeared to be a narrow-body design), with a T-tail at the end. The dozen engines were distributed evenly along the wings, with each side having four engines on the outer sections, and two between the cargo pods and fuselage. To lower runway loads, the aircraft used a massive landing gear arrangement with 56 wheels. The majority of

4136-412: The fuel for the aircraft (natural gas is mostly methane) was an obvious choice. Methane burns much cleaner than jet fuel, and would greatly extend the engine life while also reducing the need for maintenance. It would also eliminate the need to fly fuel to the northern sites, they could simply generate their fuel in-place. In order to match the capacity and economics of a 48-inch (1.2 m) oil pipeline,

4224-418: The fuselage for attaching a large freight container. Helicopters use skids, pontoons or wheels depending on their size and role. To decrease drag in flight, undercarriages retract into the wings and/or fuselage with wheels flush with the surrounding surface, or concealed behind flush-mounted doors; this is called retractable gear. If the wheels do not retract completely but protrude partially exposed to

4312-424: The fuselage lower sides as retractable main gear units on modern designs—were first seen during World War II, on the experimental German Arado Ar 232 cargo aircraft, which used a row of eleven "twinned" fixed wheel sets directly under the fuselage centerline to handle heavier loads while on the ground. Many of today's large cargo aircraft use this arrangement for their retractable main gear setups, usually mounted on

4400-438: The fuselage. The 640 t (1,410,000 lb) Antonov An-225 , the largest cargo aircraft, had 4 wheels on the twin-strut nose gear units like the smaller Antonov An-124 , and 28 main gear wheels. The 97 t (214,000 lb) A321neo has a twin-wheel main gear inflated to 15.7 bar (228 psi), while the 280 t (620,000 lb) A350 -900 has a four-wheel main gear inflated to 17.1 bar (248 psi). STOL aircraft have

4488-603: The hull out of the water at higher speeds. Hydro skis replace the need for a boat hull and only require a plain fuselage which planes at the rear. Alternatively skis with wheels can be used for land-based aircraft which start and end their flight from a beach or floating barge. Hydro-skis with wheels were demonstrated as an all-purpose landing gear conversion of the Fairchild C-123 , known as the Panto-base Stroukoff YC-134 . A seaplane designed from

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4576-471: The hydrodynamic features of the hull, long length/beam ratio and inverted spray gutter for example, allow operation in wave heights of 15 feet. The inverted gutters channel spray to the rear of the propeller discs. Low speed maneuvring is necessary between slipways and buoys and take-off and landing areas. Water rudders are used on seaplanes ranging in size from the Republic RC-3 Seabee to

4664-402: The landing gear usually consists of skis or a combination of wheels and skis. Some aircraft use wheels for takeoff and jettison them when airborne for improved streamlining without the complexity, weight and space requirements of a retraction mechanism. The wheels are sometimes mounted onto axles that are part of a separate "dolly" (for main wheels only) or "trolley" (for a three-wheel set with

4752-433: The loads. Using this many landing gear on a swept wing would produce considerable problems when the aircraft tried to turn on the ground. It was possible to use steerable landing gear legs for this, but only at the cost of added complexity. An easier solution was to simply use a straight wing so the landing gear were in a line. However, this would limit the design to slower speeds below about Mach 0.7 (see wave drag ). This

4840-415: The low-speed lift was likewise greatly increased. Further, the rectangular planform allowed the twin wing spars to be single pieces, and all of the engines, landing gear and cargo could be attached directly to the spar. With a swept wing this would place considerable torque loads on the point where the wings met the fuselage. In most other aspects the design was relatively similar to other cargo aircraft of

4928-417: The lower corners of the central fuselage structure. The prototype Convair XB-36 had most of its weight on two main wheels, which needed runways at least 22 in (56 cm) thick. Production aircraft used two four-wheel bogies, allowing the aircraft to use any airfield suitable for a B-29. A relatively light Lockheed JetStar business jet, with four wheels supporting 44,000 lb (20 t), needed

5016-504: The main gear struts lengthened as they were extended to give sufficient ground clearance for their large four-bladed propellers. One exception to the need for this complexity in many WW II fighter aircraft was Japan's famous Zero fighter, whose main gear stayed at a perpendicular angle to the centerline of the aircraft when extended, as seen from the side. The main wheels on the Vought F7U Cutlass could move 20 inches between

5104-489: The main gears, which retract aft into the ends of the engine nacelles . The rearward-retracting nosewheel strut on the Heinkel He 219 and the forward-retracting nose gear strut on the later Cessna Skymaster similarly rotated 90 degrees as they retracted. On most World War II single-engined fighter aircraft (and even one German heavy bomber design ) with sideways retracting main gear, the main gear that retracted into

5192-611: The nacelle under the control of dampers and springs as an anti-flutter device. Some experimental aircraft have used gear from existing aircraft to reduce program costs. The Martin-Marietta X-24 lifting body used the nose/main gear from the North American T-39 / Northrop T-38 and the Grumman X-29 from the Northrop F-5 / General Dynamics F-16 . When an airplane needs to land on surfaces covered by snow,

5280-444: The nosewheel/tailwheel and the two main gears. Blinking green lights or red lights indicate the gear is in transit and neither up and locked or down and locked. When the gear is fully stowed up with the up-locks secure, the lights often extinguish to follow the dark cockpit philosophy; some airplanes have gear up indicator lights. Redundant systems are used to operate the landing gear and redundant main gear legs may also be provided so

5368-722: The outset with hydro-skis was the Convair F2Y Sea Dart prototype fighter. The skis incorporated small wheels, with a third wheel on the fuselage, for ground handling. In the 1950s hydro-skis were envisaged as a ditching aid for large piston-engined aircraft. Water-tank tests done using models of the Lockheed Constellation , Douglas DC-4 and Lockheed Neptune concluded that chances of survival and rescue would be greatly enhanced by preventing critical damage associated with ditching. The landing gear on fixed-wing aircraft that land on aircraft carriers have

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5456-496: The payload. The RC-1 was designed in the early 1970s. The rapid increase in jet fuel prices after 1973 caused the project to become uneconomical. The RC-1 concept traces its history to an informal question asked of Boeing engineer Marvin Taylor. A friend who worked in the oil exploration business asked Taylor about the possibility of airlifting crude oil out of the newly discovered Alaska North Slope fields to refineries in

5544-556: The pilot's canopy. A third arrangement (known as tandem or bicycle) has the main and nose gear located fore and aft of the center of gravity (CG) under the fuselage with outriggers on the wings. This is used when there is no convenient location on either side of the fuselage to attach the main undercarriage or to store it when retracted. Examples include the Lockheed U-2 spy plane and the Harrier jump jet . The Boeing B-52 uses

5632-410: The pods was accomplished on a set of parallel railway tracks, two tracks on either side of the aircraft. The front and back halves of the pods were positioned at the end of the tracks on loaders, with the pods below the line of the wings. The aircraft would taxi into position between the rails, and the loaders would then raise the pods into position for locking onto the spars. They would then drive towards

5720-405: The return flight. Two such transfer stations were located at either end, in order to maintain the required sortie rate. The aircraft weight was so reduced after unloading that a downwind takeoff was trivially accomplished, saving the time and fuel needed to taxi to the upwind end of the middle runway. In cases of very high winds, the center runway would be used as a taxiway to return the aircraft to

5808-513: The runway loading limit . The Zeppelin-Staaken R.VI , a large German World War I long-range bomber of 1916, used eighteen wheels for its undercarriage, split between two wheels on its nose gear struts, and sixteen wheels on its main gear units—split into four side-by-side quartets each, two quartets of wheels per side—under each tandem engine nacelle, to support its loaded weight of almost 12 t (26,000 lb). Multiple "tandem wheels" on an aircraft—particularly for cargo aircraft , mounted to

5896-432: The same basic system to haul ore instead of oil. This provided the impetus to develop the ultimate RC-1 concept. To carry ore, which couldn't simply be pumped into tanks in the aircraft, the team started considering using drop-off pods that would be loaded "offline" at the sides of the airports. The pods would then be hauled to the aircraft for flight to a railhead. There, they would be dropped off and emptied onto trains while

5984-570: The same being considered for the Alaska Pipeline and Mackenzie Valley Pipeline , the system required 50 aircraft (about 15 of those being spares) each carrying about 8,000 barrels of oil and flying 24 hours a day. The aircraft were estimated to cost $ 72 million each (equivalent to $ 398 million in 2023 dollars), and fly for between 1 and 1½ cents per ton-mile. The Project was delighted by the RC-1 proposal, and several well-publicized stories about it followed. They were particularly interested in

6072-538: The same thickness pavements with a third main leg for ten wheels, like the first Boeing 747 -100, weighing 700,000 lb (320 t) on four legs and 16 wheels. The similar-weight Lockheed C-5 , with 24 wheels, needs an 18 in (46 cm) pavement. The twin-wheel unit on the fuselage centerline of the McDonnell Douglas DC-10 -30/40 was retained on the MD-11 airliner and the same configuration

6160-418: The sea lanes were ice-free for only a few months a year, and building a railhead to even the closest suitable shore point would still require hundreds of miles of rail to be laid over tundra . A pipeline would have to cross both land and water, and was likewise considered extremely difficult to build. The Project team became aware of Boeing's work with the 747F, and contacted them about the possibility of using

6248-451: The south. Taylor's back-of-the-envelope calculations demonstrated such a system would cost many times the market price of the oil. A series of injunctions against the Trans-Alaska Pipeline System imposed in April 1970 created the possibility that the oil from these fields would be stranded. Among a variety of potential solutions being offered, Boeing started a much more serious evaluation of

6336-508: The takeoff dolly/trolley and landing skid(s) system on German World War II aircraft—intended for a sizable number of late-war German jet and rocket-powered military aircraft designs—was that aircraft would likely be scattered all over a military airfield after they had landed from a mission, and would be unable to taxi on their own to an appropriately hidden "dispersal" location, which could easily leave them vulnerable to being shot up by attacking Allied fighters. A related contemporary example are

6424-494: The two spars. The cylinders were mated to aerodynamic fairings while being prepared on the ground, depending on whether they were going to be on the front or rear of the wing. The wing itself had a "plug" section that locked on onto the pods. When combined on the wing the result was a single streamlined pod about 150 feet (46 m) long, about the same length as a 707 . The pods could carry approximately 2,000 barrels of oil or 500,000 pounds (230,000 kg) of other cargo. Loading

6512-422: The vehicle on landing and during subsequent surface movement, and is not used for takeoff. Given their varied designs and applications, there exist dozens of specialized landing gear manufacturers. The three largest are Safran Landing Systems , Collins Aerospace (part of Raytheon Technologies ) and Héroux-Devtek . The landing gear represents 2.5 to 5% of the maximum takeoff weight (MTOW) and 1.5 to 1.75% of

6600-685: The water suction on the afterbody. Two steps were used on the Kawanishi H8K . A step increases the drag in flight. The drag contribution from the step can be reduced with a fairing. A faired step was introduced on the Short Sunderland III. One goal of seaplane designers was the development of an open ocean seaplane capable of routine operation from very rough water. This led to changes in seaplane hull configuration. High length/beam ratio hulls and extended afterbodies improved rough water capabilities. A hull much longer than its width also reduced drag in flight. An experimental development of

6688-534: The way that it allowed them to have market flexibility; the RC-1 could reach pipelines in Cochrane, Ontario , any one of the existing pipe heads in Alberta , or any point between. If market demands changed, they could simply ship the gas to a different location, thereby avoiding the cycling of prices seen between the various points on the pipeline network. The Project also studied tankers and freighters able to drive

6776-419: The wheels were located on eight legs with six wheels each, four to a side spread along the underside of the wings to distribute the loads. The nose gear used a single leg with eight wheels, itself the size of a 747's main gear. Fully deployed, the gear required a 400 feet (120 m) wide runway, but if the aircraft was unloaded, the outer gear could be raised to allow landings on existing commercial runways. This

6864-423: The wings reduced, cargo could be carried along the spans or in the wing tanks. With these changes, in mid-summer 1970 Boeing presented a plan that could deliver oil for $ 1.50 to $ 2.00 a barrel (equivalent to $ 9.08 to $ 12.11 in 2023 dollars). The oil companies were not interested. At the time, a barrel sold for about $ 3 (equivalent to $ 18.17 in 2023 dollars). In 1970 Canadian Prime Minister Pierre Trudeau started

6952-499: The wings was raked forward in the "down" position for better ground handling, with a retracted position that placed the main wheels at some distance aft of their position when downairframe—this led to a complex angular geometry for setting up the "pintle" angles at the top ends of the struts for the retraction mechanism's axis of rotation. with some aircraft, like the P-47 Thunderbolt and Grumman Bearcat , even mandating that

7040-424: The wingtip support wheels ("pogos") on the Lockheed U-2 reconnaissance aircraft, which fall away after take-off and drop to earth; the aircraft then relies on titanium skids on the wingtips for landing. Some main landing gear struts on World War II aircraft, in order to allow a single-leg main gear to more efficiently store the wheel within either the wing or an engine nacelle, rotated the single gear strut through

7128-479: Was able to offer the RC-1 as a replacement, allowing trans-shipment to any suitable port, railhead or pipeline. In these latest studies, costs were between 86 cents and $ 1.02 per barrel. By this point Boeing had invested about $ 500,000 of their own money in the RC-1 study series. With interest from both Canada and the US, the Great Plains Project was confident they would be able to gather a group of companies willing to fund

7216-445: Was common during the early propeller era, as it allows more room for propeller clearance. Most modern aircraft have tricycle undercarriages. Taildraggers are considered harder to land and take off (because the arrangement is usually unstable , that is, a small deviation from straight-line travel will tend to increase rather than correct itself), and usually require special pilot training. A small tail wheel or skid/bumper may be added to

7304-455: Was perfectly acceptable for short-haul role, where the cruise times were so short that added speed would have little actual effect on round-trip times. By limiting themselves to speeds not much greater than propeller transports, the engineers were free to select a wing designed solely for low-speed high-lift performance. The result looked much more like the wing from a 1930s airliner than a modern jet aircraft. A final consideration, especially for

7392-427: Was primarily intended for short-haul flights, between 500 and 1,000 miles (800 and 1,610 km), with rapid turnaround at the ends. This reduced the need for high cruising speeds. The low-speed concept allowed the design to dispense with several features normally found on jet aircraft, notably the sweptback wing . By using a conventional rectangular wing, the high-speed drag was greatly increased (see wave drag ) but

7480-449: Was solved by strengthening the engine casing and adding yoke-shaped thrust links. JT9D engines powering USAF Boeing E-4 A airborne command posts were designated F105 . All variants have the same number of compressor and turbine stages. Data from Pratt & Whitney Related development Comparable engines Related lists Landing gear Landing gear is the undercarriage of an aircraft or spacecraft that

7568-567: Was the first high bypass ratio jet engine to power a wide-body airliner . Its initial application was the Boeing 747-100 , the original "Jumbo Jet". It was Pratt & Whitney 's first high-bypass-ratio turbofan. The JT9D program was launched in September 1965 and the first engine was tested in December 1966. It received its FAA certification in May 1969 and entered service in January 1970 on

7656-467: Was used on the initial 275 t (606,000 lb) Airbus A340 -200/300, which evolved in a complete four-wheel undercarriage bogie for the heavier 380 t (840,000 lb) Airbus A340-500/-600. The up to 775,000 lb (352 t) Boeing 777 has twelve main wheels on two three-axles bogies, like the later Airbus A350 . The 575 t (1,268,000 lb) Airbus A380 has a four-wheel bogie under each wing with two sets of six-wheel bogies under

7744-438: Was useful for ferrying and service flights. Cargo was carried in wing-mounted pods, each consisting of a cylinder 26 feet (7.9 m) in diameter and about the same length as a semi-trailer . This size was selected to allow them to carry standard 8 by 8 feet (2.4 by 2.4 m) cargo containers in a 2-by-2 arrangement, the same as the 747F. Each aircraft would carry four such pods, two on either side, one each in front and behind

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