Comments for Sentry Aircraft Cylinders

Comment on why is turbine made to cool down before switching off the aircraft engine? by Kasey C

Kasey C — Thu, 02 Feb 2012 18:23:30 +0000

Turbine runs at THOUSANDS of degrees. If you let it cool too fast you shorten its life by messing with the metallurgy. Rapid cooling means the existing single-piece crystal can fracture into multiple pieces thus can develope crack along the “seams”.

The “cool down” does NOT fix creep. Creep happens over a period of time as result of repeated stress.

—
Kasey C, PC guru since Apple II days
Computer: pen for people who have bad handwriting.

Comment on why is turbine made to cool down before switching off the aircraft engine? by ³ ɱẫɳ ợƒ ɱ¥şŧƹ╓ƴ --------------------- éáŧ ɱƹ±áº«é

³ ɱẫɳ ợƒ ɱ¥şŧƹ╓ƴ --------------------- éáŧ ɱƹ±áº«é — Thu, 02 Feb 2012 17:38:14 +0000

Another reason to allow a turbine to idle down and cool is to prevent the bearings from ‘coking’ when the engine stops.

Comment on why is turbine made to cool down before switching off the aircraft engine? by skipper747

skipper747 — Thu, 02 Feb 2012 16:55:38 +0000

You could immediately shut down turbine engines if they were at idle during approach and landing. But in practice, as they are used i.e. during landing roll (reverse thrust) they need to be stabilized – After landing, in a 747, before shut down of the inboard engines (during taxi) we wait 2 minutes to cool off the turbine so to stabilize the temperature of the turbine blades and exhaust – to prevent creep -

Comment on How long an aircraft can fly if one engine fail during a flght over an ocean? by desperatehotelier

desperatehotelier — Mon, 30 Jan 2012 00:58:33 +0000

The A 340 is not a twin engine aircraft. Its a quad… The tein engine aircraft operating transatlantic flights are A 310 and 330, B 757, 767 and 777. All these twin engine aircraft have to be “ETOPS” certified. It stands for “Extended Twin Engine Operations”.

In case on an engine failure, an aircraft can fly up to 180 minutes on one remaining engine but has to divert as soon as possible. On transatlantşc flights, you always have an airport around in such a case….

The 3 or 4 engine aircraft are exepmt form this rule. They can fly on 3 engines for as long as they want if tey opt to do so… Recently a British Airways B 747 flew from Seattle to London on 3 engines only….

For more info visit: http://en.wikipedia.org/wiki/ETOPS

Comment on How long an aircraft can fly if one engine fail during a flght over an ocean? by Jose Rafael I

Jose Rafael I — Mon, 30 Jan 2012 00:18:17 +0000

Well I’m pretty sure one engine can hold the plane up for some time, at least enough for the pilot to reboot the other engine

Comment on How long an aircraft can fly if one engine fail during a flght over an ocean? by IceTrojan

IceTrojan — Mon, 30 Jan 2012 00:16:35 +0000

Yes.. in fact, they’re designed to. Most are certified to fly up to 180 minutes on one engine.

Google “ETOPS” for more information.

Comment on how is density related to an aircraft engine being able to produce more or less thrust during a hot/cold day? by captsead0nkey

captsead0nkey — Thu, 26 Jan 2012 08:20:59 +0000

Ok, no one answered the question of density.
Humidity is water vapor that is suspended in an airmass.
Water Vapor molecules are less dense than air molecules, meaning that the more water vapor (humidity) air has the less dense it is. Density is mass per volume, so the more mass it has the more dense, meaning the drier the air has more higher the density. Temperture is related to volume and pressure, so the higher the temperture, the more volume, and less pressure. so if mass is constant, and volume is increased (higher temp), the less dense it is. This is why cold, dry days have the highest density, and usually pressure will be much higher than hot days.

In physics, Force = Mass x Acceleration, so the more mass a volume of air has the more force is can produce when accelertion is constant. This is how an engine can produce more power when flying in cold dry air, as the air has more mass, and the acceleration (combustion) of the engine is constant, the more power it can create.

Comment on how is density related to an aircraft engine being able to produce more or less thrust during a hot/cold day? by silk101

silk101 — Thu, 26 Jan 2012 07:27:25 +0000

When the air is more dense (at lower altitudes) the engine is more efficient. This means the engine is slightly less efficient when the air is less dense.

Comment on how is density related to an aircraft engine being able to produce more or less thrust during a hot/cold day? by Ask Dr. Dingo

Ask Dr. Dingo — Thu, 26 Jan 2012 07:19:10 +0000

Folks! It is the atmospheric pressure we are talking about for low or high engine thrust….

The equation for calculating the thrust of an engine with the same pressure both inside and outside of the engine is F = (me/te x Ve) – (mi/ti x Vi), where me is an amount (mass) of the gas exiting the engine and te is the amount of time it takes for all of this mass of gas to pass through a given area. Ve is the velocity of this exiting gas, mi is an amount (mass) of the air just before it enters the front of the engine, and ti is the time it takes for this mass to pass through a given area. Vi is the velocity of the entering air. To make the terms more understandable, the terms with the subscript “e” refer to events and amounts relating to the exit of gas. The terms with the subscript “i” refer to events and amounts relating to the intake of gas.

In other words, the total thrust created is the force of the gas being ejected out of the back of the engine minus the force of the gas entering at the front.

Agreed that dense or cold air is thick but we should not forget that hot air expands rapidly. So, a dense air volume entering the engine will effect an efficient combustion. And that’s why, not only the aircraft engines, in automobiles also it is advisable to run it idle for a couple of minutes before accelerating so that the better combustion takes place later.

Further, one of my relative who flies a Gulfstream V often says that during a rough weather encounter or in a bad weather where the outside temperature is too low and humidity is higher his engine sound changes and power drops to a level that he can sense it (i.e. without looking at the instruments)!

Comment on how is density related to an aircraft engine being able to produce more or less thrust during a hot/cold day? by deepseteyes

deepseteyes — Thu, 26 Jan 2012 07:17:07 +0000

guy no.1 answer is OK but just add a few nice to know which I happen to know during my B737 re-currency course.
A good example of thrust is your back to a wall and you kick the wall to propel yourself forward that is thrust and the wall behind you is the air now think of it being dense or thin the thrust will be lessen isn’t it?