Re: How and when the modern propeller jet planes invented?

Greetings Janette:

References: History Of Aviation - 50 of the greatest aircraft in the history of flight
Note: there is a typographical error on this web site. The Vickers Viscount first flew in
1948 not 1968. It entered airline service in 1953 as noted.

http://www.whom.co.uk/s quelch/bb_aviate.htm

The Epic of Flight- The Jet Age
Time-Life Books, Alexandria, Virginia, USA, 1982

The world's first turbine-powered airliner, the “prop-jet” or “turboprop” Vickers Viscount
was a milestone in air transport. It first flew in July 1948, and entered service with British
European Airways in January 1953. Early doubts about turbine engines were swept away
with orders from operators in 48 countries. Over three- quarters of the 445 built
were sold abroad, a significant customer being Capital Airlines of the USA.
The Viscount's four Rolls-Royce Darts enabled it to carry 65 people at 330 mph
over 1800 miles. You can find pictures of the Vickers Viscount, which was developed in the
United Kingdom, on the following web site:

http://www.airliners.net/

The turboprop engine is an effort to combine the best features of turbojet and propeller
aircraft. The turbojet is more efficient at high speeds and high altitudes; the propeller is
more efficient at speeds under 400 mph and below 30,000 feet. The turboprop uses a gas
turbine to turn a propeller. Its turbine uses almost all the engine's energy to turn its
compressor and propeller, and it depends on the propeller for thrust, rather than on the
high-velocity gases going out of the exhaust. Strictly speaking, the turboprop is not a jet.

The gas turbine can turn a propeller with twice the power of a reciprocating engine.
Reduction gears slow the propeller below the turbine's rpm, and this must be done because
of the limitations of propellers. That is, no propeller is capable of withstanding the forces
generated when it is turned at the same rate as that of the gas turbine. Even so, the
turboprop engine receives fairly extensive use in military and civilian aviation circles.

The major disadvantages of turbojets have been the high fuel consumption and poor
performance at low power setting, low speeds, and low altitudes. In modern times
turboprop and turbofan developments have greatly improved aircraft turbine engines in
these areas.

Best regards, Your Mad Scientist
Adrian Popa