During the Second World War, the Americans used airplanes with four propellerdri

Question

During the Second World War, the Americans used airplanes with four propellerdriven engines in bombing raids, with two engines mounted on each wing, one nearer the fuselage, and one toward the end of the wing. One type of airplane, the Flying Fortress, was famous for its ability to land safely even after suffering severe damage; in particular, it could land with only one engine out of the four remaining. Suppose that this airplane lost three of its four engines. Would it be easier to fly with

• one of the engines nearest the wingtip, or

• one of the engines nearest the fuselage

remaining? Why?

In another case, one such airplane lost hydraulic power, and could no longer steer the airplane in the normal way. However, the pilot landed it safely by adjusting the power supplied to the engines (all of which were undamaged). How could a pilot steer the airplane simply by adjusting engine power?

Explanation / Answer

A number of aircraft have been claimed to be the fastest propeller-driven aircraft. This article presents the current record holders for several sub-classes of propeller-driven aircraft that hold recognized, documented speed records. Fédération Aéronautique Internationale (FAI) records are the basis for this article.[1] Other contenders and their claims are discussed, but only those made under controlled conditions and measured by outside observers. Pilots during World War II sometimes claimed to have reached supersonicspeeds in propeller-driven fighters during emergency dives, but these speeds are not included as accepted records.

Aircraft that use propellers as their prime propulsion device constitute a historically important subset of aircraft, despite inherent limitations to their speed. Aircraft powered by piston engines get virtually all of their thrust from the propeller driven by the engine. A few piston engined aircraft derive some thrust from the engine's exhaust gases, and there are certain hybrid types like the Motorjet that use a piston engine to drive the compressor of a jet engine, which supplies the primary thrust (although some types also have a propeller powered by the piston engine for low speed efficiency). All aircraft prior to World War II (except for a tiny number of early jet aircraft and rocket aircraft) used piston engines to drive propellers, so all Flight airspeed records prior to 1944 were necessarily set by propeller-driven aircraft. Rapid advances in first liquid-fueled rocket engine-powered aircraft - with a 623 mph record set in October of 1941 by a German example — and axial-flow jet engine technology during World War II meant that no propeller-driven aircraft would ever again hold an absolute air speed record. Shock wave formation in propeller-driven aircraft at speeds near sonic conditions, impose limits not encountered in jetaircraft.

Jet engines, particularly turbojets, are a type of gas turbine configured such that most of the work available results from the thrust of the hot exhaust gases. High bypass turbofans that are used in all modern commercial jetliners, and most modern military aircraft, get most of their thrust from the internal fan, which is powered by a gas turbine;turboprop engines are similar, but use an external propeller rather than an internal fan. The hot exhaust gas from a turboprop engine can give a small amount of thrust, but the propeller is the main source of thrust.

The Tupolev Tu-114, a large aircraft with four turboprop engines, has a maximum speed of 870 km/h (540 mph, Mach 0.73).[2] The 11,000 kW (15,000 hp) Kuznetsov NK-12 turboprop engines designed for the Tupolev Tu-95 (and used to power the derivative Tu-114) are the most powerful turboprops ever built and drive large contra-rotating propellers. This engine-propeller combination gives the Tu-114 the official distinction of being the fastest propeller-driven aircraft in the world, a record it has held since 1960.[1][3]

Probably the fastest aircraft ever fitted with an operating propeller was the experimental McDonnell XF-88B, which was made by installing an Allison T38 turboshaft engine in the nose of a pure jet-powered XF-88 Voodoo. This unusual aircraft was intended to explore the use of high-speed propellers and achieved supersonic speeds.[4] This aircraft is not considered to be propeller-driven since most of the thrust was provided by two jet engines.

An oft-cited contender for the fastest propeller-driven aircraft is the XF-84H Thunderscreech. This aircraft is named in Guinness World Records, 1997, as the fastest in this category with a speed of 1,002 km/h (623 mph, Mach 0.83).[5] While it may have been designed as the fastest propeller-driven aircraft, this goal was not realized due to its inherent instability.[6] This record speed is also inconsistent with data from the National Museum of the United States Air Force, which gives a top speed of 837 km/h (520 mph, Mach 0.70),[7] slower than the Tu-114.

The more "traditional" class of propeller-driven aircraft are those powered by piston engines, which include nearly all aircraft from the Wright brothers up through World War II. Today piston engines are used almost exclusively on light, general aviation aircraft. The official speed record for a piston plane is held by a modified GrummanF8F Bearcat, the Rare Bear, with a speed of 850.24 km/h (528.31 mph) on 21 August 1989 at Las Vegas, Nevada United States of America.[8][9]

The FAI record for the fastest piston-powered aircraft over a long-distance circuit is the 2000-km record of 720.13 km/h (447.47 mph) set on 22 May 1948 by Jacqueline Cochran in a P-51C. (She also holds the 100-km record of 755.67 km/hr, set in December 1947.) Higher speed records exist; some are unofficial and some were officially-timed one-way trips aided by tailwinds. Examples of the latter: a B-29 averaged 725 km/hr from Burbank to Floyd Bennett Field (3957 km in 5.455 hours) on 11 December 1945, and Joe DeBona averaged 904 km/hr from Los Angeles LAX to New York Idlewild (3981 km in 4.405 hours) in a P-51 on 30 March 1954.

so it is clear that we can suppose to fly without any engine

it may be possible to land safely with not harmed engines

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