In the Spring 2005 Issue of
My Wife Calls it an OBSESSION !!!!
Part 2: Bristol Hydra
"The Bristol Hydra is a 16-cylinder, twin row, twin overhead camshaft, poppet valve unit with the two rows of cylinders in line to allow for the camshafts. There are only two valves per cylinder, which are operated by the overhead cams through bucket tappets. I had seen the Bristol Hydra when I had first visited the Industrial Museum and had been fascinated by its complete difference to any of the other engines. It had been returned to the collection at the Rolls-Royce Heritage Trust so that I had an opportunity to study it in more detail."
Images of Brian Perkins' Hydra model engine.
Aero Engine Drawings by Frank Munger
Low Bypass Turbofan Engines
Following the development and application of the centrifugal and axial-flow
turbojet engines manufacturers continued development of a second-generation of
jet engine, the low bypass turbofan. This arrangement is one where some of the
air from the low-pressure front fan is “by-passed” outside of the “hot” core,
but within the casing of the engine, before being mixed with the hot airflow at
the jet efflux. The bypass ratios (BPR) of these engines are usually values up
to 1:1. To allow the turbofan engine to meet various flight demands, it was
found that a twin-shaft design would allow the low-pressure (LP) turbine,
driving the front fan and low-pressure (LP) compressor, to reach its optimum
operating speed, while the high-pressure (HP) turbine, driving the high-pressure
(HP) compressor, could then find its own optimum operating speed. Three-shaft
turbofans (e.g. the RB.199), have an added Intermediate (IP) compressor and (IP)
turbine.
Torquemeters
When
the use of planetary propeller reduction gears became more widespread in the
early 1930s, it did not take long for someone to realize that with all those
equal and opposite reactions going on inside the nose case, some might lend
themselves to measuring torque. With this knowledge and a little math a pilot
could tell exactly how much power was being delivered to the propeller in real
time.
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