Helicopter engines

Ignition sequence of a helicopter engine. Hot gases (yellow) are injected through two burners and the flame propagates so that all 18 burners are eventually ignited. (From Boileau, M., Ignition of two-phase flow combustors. PhD, Institut National Polytechnique de Toulouse and CERFACS, 2007.)... 

As the performance of structural adhesives has unproved, so has the ability for the helicopter engineers to operate under tighter design tolerances. This enables an enhanced performance to be obtained from the re-optimised structures. One example is the EHlOl helicopter, which has a significantly improved lifting capacity, over the older Sea King, without the need for an increased rotor diameter or number of blades. The overall construction of the EH 101 Merlin helicopter can be seen in the following schematic (Fig. 73). 

The turboprop engine has a power turbine instead of the nozzle as seen in Figure 4-2. The power turbine drives the propeller. The unit shown schematically is a two-shaft unit, this enables the speed of the propeller to be better controlled, as the gasifier turbine can then operate at a nearly constant speed. Similar engines are used in helicopter drive applications and many have axial flow compressors with a last stage as a centrifugal compressor as shown in Figure 1-14. 

Russian-American aeronautical engineer Igor Sikorsky makes the first successful tethered helicopter flight. 

The inability of the engine to produce a useful propulsive force at zero or low flight speeds necessitates the use of an auxiliary power plant to initially accelerate the vehicle to the required take-over speed of the ramjet. Such auxiliary power is also required for controlled landing of the vehicle. As a consequence the ramjet engine is not well-suited for conventional aircraft applications (with the exception of the helicopter) and the principal application of the engine appears to be further restricted to missiles or other similar vehicles of a one-flight expendable nature ... 

The readiness with which many organizations and individuals collaborated with each other and with the Science Service made possible tests on an imusually large scale, and the principle of insect control by thermal aerosol fogs has been developed and perfected rapidly. It has taken only 5 years to progress from a mere idea to practical use with helicopters and jet engines. 

Helicopter down wash has been successful in a very limited number of cases. To be successful. Ihe fog must he very shallow, and the air above the fog, bolh dry and warm, fixhausl plumes from jet engines have had some success in a number of European airports, notably at Orly (Paris). 

Carbon fibres are manufactured from rayon and polyacrylonitrile. Carbon fibres can be heated up to 1500°C and contains up to 95% of elemental carbon. Graphite fibres can be heated above 2500 C with 99% carbon. The formation of carbon fibres from polyacrylonitrile is outlined in Fig. 1 -34. Carbon fibres are used in the aerospace industry, in compressor blade to jet engines, helicopter rotor- blades, aircraft fuselage structures, golf-club shafts, cross-bows for archery and in high speed reciprocating parts in loom. 

Helicopters usually have a lower productivity in terms of the cost of operation. They tend to lift less material for a given cost and distance travelled, (less payload per engine horsepower)... 

Helicopters have been traditionally favoured for use in this part of Australia given their inherent advantages in manoeuvrability and ease of operation in built-up areas. A helicopter is generally less cost effective than a fixed-wing aircraft in terms of payload to engine horsepower (Tables 6.3 and 6.4), but is able to perform productively where its performance characteristics can be used to advantage. 

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