why does a cover on a jet engine in a passenger plane open up on landing?

Answer 1

There's a few right answers but lets do the whole cycle.
Coming in for a landing the pilot reduces power, upon landing the landing gear has a micro switch which allows the pilot to put the engine into reverse thrust. The micro switch is a safety device which prevents the engines being able to go into reverse thrust mode until the landing gear makes contact with the runway, thus preventing the airplane from falling out of the air.
When you think about a very heavy airplane coming in for a landing at 140+kts the pilot wants to bleed off as much speed possible without stalling just prior to the gear making contact with the runway so it doesn't require as much breaking power to bring the aircraft to a stop.
Landings are the hardest part of flying. Lots of thing are going on most people aren't even aware of.
On approch the pilot needs to reduce power and slow the plane down plus add some flaps as the plane needs more lift at slower speeds, all the time keeping on line with the runway and on the glideslope. If at any time the pilot feels the approch isn't safe he well go to full power and bring his air speed up and bleed off the flaps retract his gear and do a go around (missed approch) and do it again. No biggie, just being safe.

Answer 2

This cover, called a "cowling" slides forward to expose a duct that runs around the periphery of the engine. This duct is called a "fixed cascade". When the fixed cascade is open, the bypass air is prevented from being blown out the back of the engine and insteaad, is blown forward through the fixed cascade which reverses the engine's thrust. A fixed cascade type thrust reverser is used on high-bypass turbofan engines.

There is another type of thrust reverser used. It is called the "blocker", the "clamshell", or the "bucket" type. These three terms all represent the same type. This type of thrust reverser is used on either low-bypass turbofans or turbojet engines. It has two "blockers" on the back side of the engine that extend off the back of the engine, and join together to prevent exhaust air from being blown out the back of the engine. The exhaust air slams into the blockers and is blown forward. A fixed cascade wouldn't work on a turobjet because there is no bypass air. On a low-bypass turbofan the engine may not get enough thrust from the bypass air for a fixed cascade to be effective.

Virtually all large jet engines manufactured within the past couple of decades are high-bypass turbofans. They develop a lot more thrust for any specific fuel flow compared to a turbojet, they are a lot quieter, and compared to a turbojet that develops an identical amount of thrust, they weigh less.

Answer 3

The simplest and most correct answer would be the redirection of the engine's thrust. The thrust is pushed back in normal flight, and re-directed forward to aid the slowing of the plane. This 'reverse thrust' only contributes to a small percent of the stopping power of most large aircraft. The brakes would do the rest.

Answer 4

Aerodynamics, it helps slow down the jet by creating a resistance to the velocity of the wind & speed. It also helps control the direction of the airplane, left/right. The G-Force is
sometimes strong, pending on wind condition(s). This also applyes to the tail rudder, we just don't see it operating as a passenger.

Answer 5

That's a thrust reverser. It's used to slow down the plane without using the brakes. This keeps brake wear to a minimum and prevents overheating.

Answer 6

It's called a "thrust reverser" and serves to redirect the thrust of the engine in the opposite direction, thereby slowing the aircraft down.

Answer 7

these r known as thrust reversers which deploy the engine covering so that they close the engine exhaust ad direct the engine pwr forward to minimize the break wear and hence increase the braking life

Answer 8

reverses the airflow through the engine in order to act as a brake

Answer 9

Its an air flap used to create drag, they are putting on the brakes.

Answer 10

wind resistance to help stop the plane.