The world’s largest turboprop aircraft is still in active use, it is non-other than the Antonov An-22 “Antei” which is mainly used by the Russian military and is an impressive aircraft.
Why the large Antonov AN-22 Turboprop aircraft was built: Back in the USSR in the 1950s, the Soviet military required a new aircraft to help transport infantry, humanitarian aid, and its new range of BMD tanks. The current plane for this purpose was not big enough, and they needed something to remain competitive to the west.
Thus the engineers at the Antonov bureau got to work and produced a wooden prototype by 1965. It was so impressive that officials decided to show it off at the Paris Air Show that very same year.
The actual production model of the aircraft would not fly until 1969. It would replace the wood with metal and would install more up to data avionics. Improvements included a radar installed in the nose and would also have a pressurized cargo compartment (so the plane could deploy airdropped cargo in flight without affecting the cockpit crew).
It could carry 28–29 passengers and 80,000 kg (176,370 lb) maximum payload to a range of 5,000 km (3,100 mi, 2,700 nautical miles). If only carrying 45,000 kg (99,208 lb) it can fly a range of 10,950 km (6,800 mi; 5,910 nautical miles).
This is a pretty fantastic range considering the size and the scale of the aircraft.
What is unique about this aircraft is that they designed it to land on rugged unpaved airstrips (and short runways). To put this in perspective how insane this is, let’s compare it to the American C-17 Globemaster:
The An-22 needs 1,300 m (4,265 ft) of runway to take off and only 800 m (2,625 ft) to land.
The C-17 needs a runway 2,499 m (8,200 ft) to take off fully loaded, and at least 1,067 m (3,500 ft) with maximum payload.
The aircraft has counter-rotating propellers, thus dramatically improving the lifting capacity of the plane. However, these propellers significantly reduce the speed of the aircraft to only 740 km/h (460 mph, 400 knots) compared to jet engines.
The An-22 has an impressive range and tiny runway requirement.
It was able to adjust the tire pressure of each wheel depending on the surface (be it concrete, gravel, dirt, or even snow). While more modern aircraft have removed this feature, the early versions of the An-22 had this as a mandatory feature for its military use.
Back in the 1960s, they were comparable to the Douglas C-133 Cargomaster – and American large four-engine turboprop cargo aircraft. When the US military phased out that airplane, the next plane it matched to be the Boeing C-17 Globemaster III – a four-engine military transport aircraft.
The Russian government only has three An-22’s left in service (and there is one in Ukraine and one in Bulgaria) but isn’t planning on retiring them any time soon. They want to keep them operational to at least 2033, and then replace them with the bigger An-124. (simpleflying)
A turboprop aircraft or engine is said to be a turbine engine that drives an aircraft propeller.
Turboprop consists of a compressor, combustor, turbine, and a propelling nozzle. Air is drawn into the intake and compressed by the compressor. Fuel is then added to the compressed air in the combustor, where the fuel-air mixture then combusts. The hot combustion gases expand through the turbine. Some of the power generated by the turbine is used to drive the compressor. Thrust is obtained by the combusting gases, pushing toward a (vectored) surface in front of the expanding gas.
The rest is transmitted through the reduction gearing to the propeller. Further expansion of the gases occurs in the propelling nozzle, where the gases exhaust to atmospheric pressure. The propelling nozzle provides a relatively small proportion of the thrust generated by a turboprop.
In a simplest form, Turboprop aircraft have one or more gas-turbine engines connected to a gearbox that turns the propeller(s), to move the aircraft on the ground and through the air. Turboprop aircraft burn Jet-A fuel, are frequently larger than piston-powered aircraft, can carry more payload and passengers than their piston-powered counterparts and can typically fly higher than pistons, at altitudes up to 35,000 feet. Turboprop aircraft have lower operating costs than jets because they burn less fuel, but they are also slower than jets. Turboprops are an attractive option for businesses that need to fly missions requiring 600-1,000 miles of travel between general aviation airports that often have runways too short to accommodate jets. These aircraft vary in size, but the interior of a typical turboprop is the size of a large SUV, seats 6-8 people, and is often configured similar to a small office, where co-workers can meet and make productive use of time en route to a destination.
Few companies’ manufactures turboprop aircraft, they include: Cessna, Beechcraft, Piaggio, Piper, Pilatus and Socata.