,
17 tweets,
11 min read
Read on Twitter
Mark's entry-level guide to #JetEngines.
Why jets? Good fuel economy, relatively simple & highly reliable, relatively small dimensions.
They burn very cleanly the highly energetic Jet Fuel (similar to diesel fuel).
Why jets? Good fuel economy, relatively simple & highly reliable, relatively small dimensions.
They burn very cleanly the highly energetic Jet Fuel (similar to diesel fuel).
However, obtaining good parameters requires high tech alloys & manufacturing, especially turbine blades.
Turbojet: high power up to about Mach 3. Common on fast military aircraft. Long and slender; one exhaust nozzle, often adjustable diameter. Very loud. Often equipped with afterburners.
Turbofan: good fuel economy at subsonic speed. Prolific on medium- and long-range airliners & freighters. Short and chunky; two concentric rings of exhaust. Typically well noise-abated.
Turboprop: good fuel economy at medium speeds. Prolific on small and medium passenger aircraft, and high performance small aircraft. Small engine with large exhausts and propeller.
Turboshaft: high power in small package. Commonly used in helicopters.
Ramjets and scramjets don't have a rotating turbine; instead they rely on flow of air and shape of internal passages. This makes them able to handle hypersonic flight - but they can't start from standstill.
Notable exceptions and other uses:
BAE Harrier II VTOL fighter uses turbofan engine to get separate exhaust for the front nozzle pair, to be able to take off and land vertically.
BAE Harrier II VTOL fighter uses turbofan engine to get separate exhaust for the front nozzle pair, to be able to take off and land vertically.
Russian Tu-95 subsonic long range bomber uses turboprops rather than turbofans. Due to contra-rotating propellers is exceptionally loud.
The civilian Concorde used turbojets with afterburners for their good handling of Mach 2 speeds. Its supercruise was very fuel efficient.
The fast supersonic SR-71 used turbojets that had ramjet component, allowing it to cruise at well above Mach 3. Significant portion of air was re-routed around the turbo part and dumped right into the afterburner.
Gas turbine engines (closely related to turboshafts) are commonly used for propulsion & power generation - both stationary and marine.
Gas turbine engines (closely related to turboshafts) are sometimes used to power vehicles like M4 Abrams, for the sake of high energy in compact package.
M1* Abrams, thanks @DongDiddleDop
Example of turboprop: DRACO, the high performance bush plane. Short take-off & landing, good speed & range for a small plane. Custom built from PZL Wilga, with Pratt & Whitney PT6A-28 engine.
h/t @87flying
h/t @87flying
If you see flame, it's afterburner!
Optional section in some turbojet engines behind turbine section, just before tailpipe. Some 50...60% more power at v. high fuel consumption.
Used for takeoff, combat and crossing the Mach 1 barrier. Note the "shock diamonds"
h/t @Lawnpupper
Optional section in some turbojet engines behind turbine section, just before tailpipe. Some 50...60% more power at v. high fuel consumption.
Used for takeoff, combat and crossing the Mach 1 barrier. Note the "shock diamonds"
h/t @Lawnpupper
