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Engine Efficency At DEN  
User currently offlineFutureualpilot From United States of America, joined May 2000, 2598 posts, RR: 8
Posted (10 years 5 months 3 weeks 5 days 4 hours ago) and read 1502 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?

thanks!


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 (10 years 5 months 3 weeks 5 days ago) and read 1455 times:

Dear Futureualpilot...
xxx
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...
xxx
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.
xxx
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...
xxx
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: 19
Reply 2, posted (10 years 5 months 3 weeks 5 days ago) and read 1442 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, 1875 posts, RR: 3
Reply 3, posted (10 years 5 months 3 weeks 4 days 18 hours ago) and read 1405 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 (10 years 5 months 3 weeks 4 days 17 hours ago) and read 1394 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, 2598 posts, RR: 8
Reply 5, posted (10 years 5 months 3 weeks 4 days 17 hours ago) and read 1390 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 (10 years 5 months 3 weeks 4 days 12 hours ago) and read 1376 times:

Dear Futureualpilot...
xxx
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...
xxx
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?) -
xxx
Probably, if a reciprocating airplane could climb that high, would be efficient too.
Problem, they can't get that high to start with...
xxx
Happy contrails  Smile
(s) Skipper


User currently offlineFutureualpilot From United States of America, joined May 2000, 2598 posts, RR: 8
Reply 7, posted (10 years 5 months 3 weeks 3 days 19 hours ago) and read 1308 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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