The Journey of Flight.pdf - Valkyrie Cadet

Chapter Chapter Chapter Chapter Chapter
15
bjectives
Identify at least two heavy-lift helicopters.
Identify at least two light-lift helicopters.
Define STOL and VSTOL.
Helicopters
Helicopters
The helicopter has only been with us since the end of World War II. We have already mentioned
many of its uses in agriculture, heavy lifting and hauling, and other commercial uses. Today, the big
push in civil aviation helicopters is into the executive/business aviation fields.
Helicopters have always had several drawbacks, which have made them unattractive to civilian
operators. These shortcomings include high maintenance costs, vibrations and high noise levels, and
slow cruise speeds. Advances in technology have reduced all of these shortcomings and have practically
eliminated some of them.
Turbine engines with greater power for a given weight have increased the range, speed and payload
in modern helicopters. Better engineering has produced gearboxes with fewer moving parts and gears
that run with a closer fit. This has reduced noise and vibration and has lowered maintenance costs as
well. New bearings and bushings have further reduced the noises and vibrations, and more soundproofing
has been added to the engine compartment and cabin.
Building them out of fiberglass reduced maintenance costs on the rotor. The latest trend is toward
the use of composite materials in rotor blades. The composites have the advantage of being much
stronger and lighter than earlier materials.
Militar Militar Militaryyyyy Militar Militar
Throughout this part, we have said that the category an aircraft is placed into depends entirely upon
its use. Using this logic, there are only two US helicopters that are limited strictly to military use– the
Bell AH-1 HueyCobra and AH-64 Apache.
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