Jet engines
Jet engines move the airplane forward with a great force that is produced by a tremendous thrust and causes the plane to fly very fast.
All jet engines, which are also called gas turbines, work on the same principle. The engine sucks air in at the front with a fan. A compressor raises the pressure of the air. The compressor is made with many blades attached to a shaft. The blades spin at high speed and compress or squeeze the air. The compressed air is then sprayed with fuel and an electric spark lights the mixture. The burning gases expand and blast out through the nozzle, at the back of the engine. As the jets of gas shoot backward, the engine and the aircraft are thrust forward. As the hot air is going to the nozzle, it passes through another group of blades called the turbine. The turbine is attached to the same shaft as the compressor. Spinning the turbine causes the compressor to spin.
Turning off the engines in flight
Can fighter jets switch engines off and on midair? If so, how long is the restart process?
David Tussey, former US Navy A-7E pilot and T-2 instructor, explains on Quora;
‘Well you could, theoretically, but you wouldn’t want to do that. Jet fighters tend to fall out of the sky when the engines aren’t running.
‘I flew the A-7E for the USN. It had one engine so no, you can’t turn the engine off… ever.
‘Let’s talk the time it takes to do an in-flight relight.
‘Once when I was an instructor in the T-2C “Buckeye” I was on an early FAM (Familiarzation) flight. I was in the back of course. One of the maneuvers was a power off stall, designed to instil confidence in the aerodynamics of the aircraft. The procedure was to carefully retard one engine at a time to idle, then hold altitude until the plane stalls and recover by lowering the nose to increase airspeed. Maneuver complete.
‘So, as we began the maneuver, the student inadvertently took both throttles and promptly shut down both engines. Unfortunately, the T-2C was designed so that the back seat could not start the engines; it was physically impossible to move the throttles around the shutoff detent.
T-2 instructor recalls scary in-flight relight
‘There we were, both engines shut down, as the Instructor Pilot I was unable to affect a restart, we were slow in preparation for the maneuver, and somewhat low, about 12,000 feet.
‘Fortunately, I was able to talk the student through the relight procedure. It took about a minute because he was unfamiliar with the procedure. One very scary minute until we relit one engine and moved it to full power. And we lost about 7000 feet. Then we relit the other engine.
‘So…about a minute.’
Tussey concludes;
‘That was scary, and afterwards there was a mod made to the aircraft to allow the back-seat instructor to move a bar that would block the front seat from shutting down the engines.’
Photo by Photographer’s Mate 2nd Class Daniel J. McLain / U.S. Navy
