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Engine Efficency At DEN  
User currently offlineFutureualpilot From United States of America, joined May 2000, 2613 posts, RR: 7
Posted (11 years 7 months 1 day 2 hours ago) and read 1919 times:

As we know, jet engines are designed to run more efficently at higher altitudes, so my question is, when a/c fly into DEN, or maybe SLC, or another airport up high like that, is there a significant enough altitude gaiun that the engines are more efficent than say at LAX, or maybe LAS? Also, would this save a lot for UA flying out of DEN and DL flying out of SLC on their fuel costs?


Life is better when you surf.
7 replies: All unread, jump to last
User currently offlineB747skipper From , joined Dec 1969, posts, RR:
Reply 1, posted (11 years 7 months 23 hours ago) and read 1872 times:

Dear Futureualpilot...
I am afraid you have a misunderstanding of the "original" facts about jet planes.
Efficiency of AIRPLANES (I did not say ENGINES)...
This is for CRUISE, not for takeoff and landing...
Very low altitudes, i.e. below 12,000 feet, RECIPROCATING powered planes...
Medium altitudes, i.e. 10,000 to 25,000 feet, TURBOPROP airplanes...
Higher altitudes, i.e. 25,000 to 35,000 feet, TURBOFAN jet powered planes...
Highest altitudes, i.e. above 35,000 feet, TURBOJET (non-fan) powered planes.
Now if you talk about the "efficiency" of a jet airliner for takeoff and landing, say from DEN or SLC... or BOG... nope... sea level is BEST FOR ALL AIRPLANES...
My dear friend, when you read, or hear something, you must also think about it then fully understand the information provided...
Your being with us here in Tech.Ops. will teach you a lot... but, pay attention.
Happy contrails -
(s) Skipper

User currently offlineNudelhirsch From Germany, joined Oct 2003, 1438 posts, RR: 18
Reply 2, posted (11 years 7 months 23 hours ago) and read 1859 times:

Maybe a bit different...

I heard, that on crz an upward pitch of 3° is held to fly mor efficient.
Pix of crz look like the pitch-angle is more, maybe 5-10°...
Feeling is never a type of measure, but feeling is like 0°
Seeing cabin from inside is actually like 3-5°...(see feeling...no real measure....)

What's all that about?

THX for help!

Putana da Seatbeltz!
User currently offlineFlyboy80 From United States of America, joined Jul 2001, 1897 posts, RR: 3
Reply 3, posted (11 years 7 months 17 hours ago) and read 1822 times:

There is also slightly less friction at DEN which usually required aircraft to take longer runway space when landing... you should at least know that... as far as engines, I think they really "Whip the ponnies" on aircraft out of DEN.
If Im correct, lifting devices tend to be more efficient at lower altitudes. however they still work at higher altitudes, and with less friction you can moved much faster with the same amount of power.

User currently offlineIllini_152 From United States of America, joined Jan 2001, 1000 posts, RR: 2
Reply 4, posted (11 years 7 months 16 hours ago) and read 1811 times:

Exactly- with the same ammount of power. At higher altitudes there is less air available, so the engine will also be putting out less power than at sealevel.

Happy contrails - I support B747Skipper and Jetguy
User currently offlineFutureualpilot From United States of America, joined May 2000, 2613 posts, RR: 7
Reply 5, posted (11 years 7 months 16 hours ago) and read 1807 times:

I was way off in my original thoughts! Thanks for the answers everyone, and especially skipper! I didnt consider the extra "umph" it would take for them being at higher altitudes.

Life is better when you surf.
User currently offlineB747skipper From , joined Dec 1969, posts, RR:
Reply 6, posted (11 years 7 months 11 hours ago) and read 1793 times:

Dear Futureualpilot...
Thinking about a simple way to explain why jets are efficient...
First, they can climb at high altitude...
Then at high altitude - for a given KIAS then move at a very high TAS...
Exemple - for a 727...
Say a 727 flies at sea level, indicating 300 kts KIAS...
At sea level, standard conditions, its true airspeed is... 300 Kts...
Its total fuel flow will be 9000 lbs per hour... 9000 lbs to cover 300 NM...
Now let's climb it to say, FL 310...
Still flying at same 300 KIAS... therefore still 9000 lbs fuel flow...
But now its TAS will be 480 kts...
So to cover 480 NM, the aircraft will burn 9000 lbs - that is EFFICIENT...
(and much more economical, right?) -
Probably, if a reciprocating airplane could climb that high, would be efficient too.
Problem, they can't get that high to start with...
Happy contrails  Smile
(s) Skipper

User currently offlineFutureualpilot From United States of America, joined May 2000, 2613 posts, RR: 7
Reply 7, posted (11 years 6 months 4 weeks 1 day 18 hours ago) and read 1725 times:

Once again, thank you Skipper! You always provide excellent answers! I've got the idea now, and with all the knowledge here in tech/ops I might just get it!  Laugh out loud

Life is better when you surf.
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