Who's Online

We have 1455 guests online

Live Traffic Feed

Life in the Skies

'A Local Bestseller!'

What Tony says
(See here)
and Book Launch video here
 
What others say

Les Posen
(See
here)

Yvonne Lee
(See
here)

Louisa Lim & Allan Koay
(See
here)

Aireen Omar, Asran & Bo Lingam
(See
here)

38 Readers' Comments
(See here)

Get an autographed copy here

AMAZON.COM  -  To Order, please Click here 

(eBook) Kindle edition - please Click here

Latest Comment

Thunderstorms and th
Hi Captain Lim, I would like to know if there ha

What happens if I ge
I have seen a comment from a Flight attendant that

What are the eyesigh
Captain, I am in class 11 in India and want to bec

What are the eyesigh
PLEASE stop asking about your eyes!!! Read the art

Vomiting on long hau
I have traveled a lot (almost 2 million miles) the

Can you become an ai
Hi captain , I had an accident 15 yrs ago and ha

Does a jet aircraft
Reading through the comments was both entertaining

Does a jet aircraft
So many nonsense here... Earth isn't flat. Period.

What are the cruisin
"how in the hell can you reach JFK if you leave fr

What are the eyesigh
tjsoihsdojfsioufs f post

Paperback Version

 For Local Availability - Check Here
 
Home
About engine thrust reverser and effect of rain water on jet engines
Flying - General
Written by Capt Lim   
Tuesday, 20 January 2015 10:00
 
Jet Engine Thrust Reverser

Dear Captain Lim

My question is about thrust reversers - I am a light aircraft and glider pilot in the UK and I understand that when the thrust reversers are deployed on modern engines, the flaps cut off the direction of the air in the engine, the cowl opens and the air flow is directed forward.

Now when a commercial aircraft is landing, conventional wisdom dictates the engines should be at idle in the flare or very soon after touchdown. If this is the case, the fan blades will be wind-milling and not generating thrust, so why a need for reversers. The only reason I can think of when they must use them is, where engine power is above idle?

Does this mean that the engines are kept above idle in the flare so benefit of reversal can be achieved when the aircraft lands.

My final question - Why the rain water in the air doesn’t extinguish the combustion of a jet engine? Is it because the engine is too hot?

Many thanks

Regards

Simon

Hi Simon,

Let me review the operation of thrust reversers again to clear any doubts that you may have (see also a previous similar question and answer here)

On a Rolls Royce engine, when the pilot selects the reverser thrust on landing, he has to bring the engines to idle power first before he can re-engage the reversers. When the reverse is then selected, there are blocker doors in the engine that deflect the air flow from the thrust forward. On the full re application of the reverse thrust levers, around 25 to 30 percent of the thrust would be available to help slow down the plane. (See diagram below)

 

During this process, power is now increased again from idle. Hence the increase in noise as the reversers is selected.

Your next question – why rain water does not extinguish the combustion of a jet engine?

Well, in aviation term, the extinguishing of the combustion of a jet engine is known as a flame out.

Flameouts are generally rare and rain water is unlikely to be the cause. While it can affect the function of a jet engine, it typically does not really have a significant effect.

In general, only very intense storms can affect the engine behavior and aircraft will usually avoid thunderstorms of this nature anyway.

The amount of water in the large volume of air entering an engine is still relatively small in most storms. The high temperature in the engine's combustion chamber quickly evaporates this level of water into steam that has little influence on the engine's power output.

The high bypass engine removes the rain water from the airflow before it reaches the combustion section. Hence the water is carried through the engine without ever entering the combustion chamber. The design of a jet engine allows it to remove most of water that it will ever ingest while flying through a storm. Whatever remaining water will be evaporated and can easily be handled by a jet engine. (See video below)

Interestingly, effect of water on a jet engine was noted in the Qantas Flight 32 that landed in Singapore on 4 Nov 2010. The flight suffered an uncontained engine failure four minutes after it took off from the Singapore Changi Airport

After landing, the crews were unable to shut down the No 1 engine as the electrical wiring from the cockpit were severed by the disintegrating turbine disc.

Fire services were called upon to douse out the combustion (flame) in the engine. Initially they used water from the fire truck to spray onto the No 1 engine but all the three attempts failed (see photos from changiairportgroup.com site below) to shut down the engines until about 3 hours later when it was doused by fire retardant from the foam tender truck.
 
 
Spraying water to douse the QF A380 No 1 engine
 Changi Airport (changiairportgroup.com) 


Rolls-Royce Engine Water Ingestion Test

Trackback(0)

TrackBack URI for this entry

Comments (0)

Subscribe to this comment's feed

Write comment

smaller | bigger

busy
 

Paperback Version

 For Local Availability - Check Here

Recommended By..


LIFE IN THE SKIES

'A Local Bestseller!'

Recommended by

Patrick Smith
Boston USA
(See
here)

Capt Meryl Getline
ex-United Airlines USA
(See
here)

Capt Doug Morris
Canadian Airlines
(See
here)

Capt  Robert J Boser
ex-United Airlines USA
(See
here)

38 Readers' Comments
(See here)

Get an autographed copy here

AMAZON.COM  -  To Order, please Click here 

(eBook) Kindle edition - please Click here

View Book Launch video here

Follow me

@CaptKHLim

Like What You Read?


If you like what you read, more stories are found in my book LIFE IN THE SKIES (Preview here) and you can purchase a copy here. To check for any latest updates or postings, you can follow my Twitter at @CaptKHLim or Facebook here

MH 370 Interviews

Click here to View

10 Most Popular Posts



Disclaimer | Privacy
2004 - 2011 © AskCaptainLim.com | Site Concept by eQuilec.com