Chrisba320
Topic Author
Posts: 16
Joined: Mon Sep 25, 2017 4:05 pm

Narrow body hot and high performance

Thu Apr 05, 2018 6:23 pm

Hi Guys

I’m not very technically minded so what follows is based purely on the experience of a frequent traveler.

I live in Cape Town and fly to Johannesburg all the time. Almost all my flights are on the 738 or A319/320. JNB is high above sea level and I’ve had many take-offs in 35 plus degrees centigrade. To me, as a passenger, it feels like a fully loaded A319/320 gets off the ground a lot easier than a 738. I’ve had some take-off runs on the 738 that were disconcertingly long. It takes forever to get off the ground and when it eventually happens the initial climbout is slow, noisy and shuddery. Tha A320, on the other hand, uses quite a bit less runway and seems to get off the ground with much less drama. CFM56’s on the 738, of course, IAE-2500 on the A319/320.

Like I said, the above are purely subjective observations, I’d be very interested to hear from the experts on a.net what the facts are.

Cheers.
 
Chaostheory
Posts: 1080
Joined: Wed Mar 06, 2013 2:09 am

Re: Narrow body hot and high performance

Thu Apr 05, 2018 6:41 pm

The A320/321 are quite a bit better than their counterparts where field (runway/takeoff) performance is concerned. 737-800 climb performance (not synonymous with takeoff performance) isn't bad and she'll happily keep going until temps hit isa+15.

Your post makes me smile and reminds me of (happy) days on the Airbus fleet struggling to get A321s out of Khartoum with the mercury rising above 40C.
 
WkndWanderer
Posts: 222
Joined: Sat Oct 21, 2017 6:36 pm

Re: Narrow body hot and high performance

Thu Apr 05, 2018 7:15 pm

I don't think I've ever noticed much of an appreciable difference between the 738 and the A320. The 739 and the A321's are different however. The 739 obviously has a lengthy takeoff run, but what I find interesting with A321 takeoffs is that the thrust seems to be noticeably reduced relatively quickly after rotation and then the aircraft climbs pretty passively after that. I don't get that same sensation of the power getting pulled back as quickly on the 739. Some of the more "aggressive" feeling climbs I've experienced have definitely been in the 737-700 and 757.
 
spacecadet
Posts: 3166
Joined: Thu Sep 20, 2001 3:36 am

Re: Narrow body hot and high performance

Thu Apr 05, 2018 7:18 pm

Assumed temperature thrust reduction: http://www.b737.org.uk/assumedtemp.htm

Has nothing to do with absolute performance. It has to do with intentionally minimizing engine wear.

Airbuses have something similar but they call it FLEX. There may be different requirements for FLEX vs. assumed temperature reduction, though, so you may not experience one when you would experience the other.
I'm tired of being a wanna-be league bowler. I wanna be a league bowler!
 
B777LRF
Posts: 2152
Joined: Sun Nov 02, 2008 4:23 am

Re: Narrow body hot and high performance

Thu Apr 05, 2018 7:35 pm

Generally the Vref speeds on 737-8/9 are higher than an equivalent 320/321. Some of the reasons are different wing and flap/slat system, FBW and a higher AoA without risking a tail strike. On an ISA+20 day at 5000ft, the old piglet of Renton will eat up runway like it's an open buffet. Not that any 'bus will find it a walk in the park, mind, they'll be hurting for performance too. Just not quite so much,
Signature. You just read one.
 
MIflyer12
Posts: 4039
Joined: Mon Feb 18, 2013 11:58 pm

Re: Narrow body hot and high performance

Thu Apr 05, 2018 7:36 pm

OP should, at least once, experience the take-off of a fairly empty 757 on that route. Zippy!
 
UA735WL
Posts: 244
Joined: Mon Apr 09, 2012 7:08 pm

Re: Narrow body hot and high performance

Thu Apr 05, 2018 8:23 pm

Chaostheory wrote:
The A320/321 are quite a bit better than their counterparts where field (runway/takeoff) performance is concerned. 737-800 climb performance (not synonymous with takeoff performance) isn't bad and she'll happily keep going until temps hit isa+15.
.


This is often stated as fact here and while I'm no expert, I have a bit of a hard time believing that an A320 could be *significantly* better than a 738- the A320 carries around a fair bit of extra weight when compared to a 737 (3rd hydraulic system, wider fuselage, larger, heavier and more numerous evacuation slides, to name a few things). The A320 wing also is a bit smaller as far as area is concerned so that doesn't bode terribly well for performance. However...

B777LRF wrote:
Some of the reasons are different wing and flap/slat system, FBW and a higher AoA without risking a tail strike.


...the increased ground clearance of the Airbus really helps it out in this respect. As is often mentioned in the endless NEO vs. MAX threads, the 737 sits rather low to the ground and therefore has to move a bit faster than the equivalent Airbus to leave the ground with its shallower rotation angle. This becomes most apparent in the longer variants, where the A321 beats the 739 handily. As far as the A320 and 738 are concerned I'd venture to say it's a wash- the A320's weight and wing disadvantage are cancelled out by the rotation angle. When it comes to the 73G and the A319 (where both fuselages are short enough to effectively rule out tailstrike issues) the 73G comes out on top due to the bigger wing and lighter weight as mentioned above. Just using DL as an example- they fly (flew?) the 73G into EYW with a 4800 foot runway even thought they operate both the 73G and A319 (granted, the 73Gs at DL are actually 73Ws with 26K engines).

I'm curious as to how FBW could lead to better takeoff performance- as far as I'm aware the A320 series doesn't have tailstrike envelope protection.


Jonas :bouncy:
"One test is worth a thousand expert opinions" -Tex Johnston
 
User avatar
MoKa777
Posts: 723
Joined: Fri Oct 21, 2016 11:47 am

Re: Narrow body hot and high performance

Thu Apr 05, 2018 9:09 pm

LOL my previous post was deleted!

For those of you who didn't see it, it was earth-shatteringly offensive...

I kid!

UA735WL wrote:
Chaostheory wrote:
The A320/321 are quite a bit better than their counterparts where field (runway/takeoff) performance is concerned. 737-800 climb performance (not synonymous with takeoff performance) isn't bad and she'll happily keep going until temps hit isa+15.
.


This is often stated as fact here and while I'm no expert, I have a bit of a hard time believing that an A320 could be *significantly* better than a 738- the A320 carries around a fair bit of extra weight when compared to a 737 (3rd hydraulic system, wider fuselage, larger, heavier and more numerous evacuation slides, to name a few things). The A320 wing also is a bit smaller as far as area is concerned so that doesn't bode terribly well for performance. However...

B777LRF wrote:
Some of the reasons are different wing and flap/slat system, FBW and a higher AoA without risking a tail strike.


...the increased ground clearance of the Airbus really helps it out in this respect. As is often mentioned in the endless NEO vs. MAX threads, the 737 sits rather low to the ground and therefore has to move a bit faster than the equivalent Airbus to leave the ground with its shallower rotation angle. This becomes most apparent in the longer variants, where the A321 beats the 739 handily. As far as the A320 and 738 are concerned I'd venture to say it's a wash- the A320's weight and wing disadvantage are cancelled out by the rotation angle. When it comes to the 73G and the A319 (where both fuselages are short enough to effectively rule out tailstrike issues) the 73G comes out on top due to the bigger wing and lighter weight as mentioned above. Just using DL as an example- they fly (flew?) the 73G into EYW with a 4800 foot runway even thought they operate both the 73G and A319 (granted, the 73Gs at DL are actually 73Ws with 26K engines).

I'm curious as to how FBW could lead to better takeoff performance- as far as I'm aware the A320 series doesn't have tailstrike envelope protection.


Jonas :bouncy:


^^ I find this particularly interesting and informative!
Never be proud. Always be grateful.
 
UA735WL
Posts: 244
Joined: Mon Apr 09, 2012 7:08 pm

Re: Narrow body hot and high performance

Thu Apr 05, 2018 9:17 pm

MoKa777 wrote:
LOL my previous post was deleted!

For those of you who didn't see it, it was earth-shatteringly offensive...

I kid!


Did you see the one immediately after yours? :bigthumbsup: :checkeredflag:

MoKa777 wrote:
^^ I find this particularly interesting and informative!


Glad I could help. It's rather nice (and unfortunately rare) to have a civil discussion on this site nowadays. :wave:

Jonas :bouncy:
"One test is worth a thousand expert opinions" -Tex Johnston
 
User avatar
MoKa777
Posts: 723
Joined: Fri Oct 21, 2016 11:47 am

Re: Narrow body hot and high performance

Thu Apr 05, 2018 10:28 pm

UA735WL wrote:
MoKa777 wrote:
LOL my previous post was deleted!

For those of you who didn't see it, it was earth-shatteringly offensive...

I kid!


Did you see the one immediately after yours? :bigthumbsup: :checkeredflag:

MoKa777 wrote:
^^ I find this particularly interesting and informative!


Glad I could help. It's rather nice (and unfortunately rare) to have a civil discussion on this site nowadays. :wave:

Jonas :bouncy:


Gasp! No, I did not! Well, it must have been bad for my comment to also be removed. Flamebait by association! Haha

It is nice to have a civil discussion. Given the topic of said discussion, it is so much nicer! Let's hope it stays that way.
Never be proud. Always be grateful.
 
Chaostheory
Posts: 1080
Joined: Wed Mar 06, 2013 2:09 am

Re: Narrow body hot and high performance

Thu Apr 05, 2018 11:58 pm

UA735WL wrote:
Chaostheory wrote:
The A320/321 are quite a bit better than their counterparts where field (runway/takeoff) performance is concerned. 737-800 climb performance (not synonymous with takeoff performance) isn't bad and she'll happily keep going until temps hit isa+15.
.


This is often stated as fact here and while I'm no expert, I have a bit of a hard time believing that an A320 could be *significantly* better than a 738- the A320 carries around a fair bit of extra weight when compared to a 737 (3rd hydraulic system, wider fuselage, larger, heavier and more numerous evacuation slides, to name a few things). The A320 wing also is a bit smaller as far as area is concerned so that doesn't bode terribly well for performance. However...



It is an undisputable fact.

Whilst the 738 may have a lower empty weight, the different wing design (important to note not inferior), slightly lower thrust engines and most importantly limited rotation angle (higher aoa=more lift) really does impede it versus the A320 during takeoff. Assuming 75t TOW, depending on flap config, the 737 requires a 10-15knots higher vr than the A320. You need more runway to reach that higher takeoff speed (well duh!). Look it up in the performance charts if you don't believe me. FPPMs, AFMs and FCOMs have all the information you need. Even with isa+25 temps where I work, the A320 is rarely field limited.

The A320s performance really is quite remarkable when you take into account the 80s design wing. Those BAE wing designers knew a thing or two about field performance and they put the experience garnered through the A300 development into the A320.
 
AA737-823
Posts: 5334
Joined: Wed Mar 01, 2000 11:10 am

Re: Narrow body hot and high performance

Fri Apr 06, 2018 1:07 am

You've brought up the A319 in the original picture; it's important to consider that the 319 is significantly less aircraft than the bigger brother 320/738.
I've always found the 319 and 737-700 to be pretty sprightly in takeoff and initial climb.
Otherwise, both aircraft families are pretty similar in performance. Until you get to the 739/321, which is a bit of a different conversation.
Others have covered all the other topics I initially thought of, except to point out that the engine manufacturer (which was brought up in the OP) has very little to do with anything; when you ask an A320 to give you 22,000 pounds of thrust, it will do so, whether it has CFMs or IAEs installed.
 
UA735WL
Posts: 244
Joined: Mon Apr 09, 2012 7:08 pm

Re: Narrow body hot and high performance

Fri Apr 06, 2018 4:27 am

Chaostheory wrote:
UA735WL wrote:
Chaostheory wrote:
The A320/321 are quite a bit better than their counterparts where field (runway/takeoff) performance is concerned. 737-800 climb performance (not synonymous with takeoff performance) isn't bad and she'll happily keep going until temps hit isa+15.
.


This is often stated as fact here and while I'm no expert, I have a bit of a hard time believing that an A320 could be *significantly* better than a 738- the A320 carries around a fair bit of extra weight when compared to a 737 (3rd hydraulic system, wider fuselage, larger, heavier and more numerous evacuation slides, to name a few things). The A320 wing also is a bit smaller as far as area is concerned so that doesn't bode terribly well for performance. However...



It is an undisputable fact.

Whilst the 738 may have a lower empty weight, the different wing design (important to note not inferior), slightly lower thrust engines and most importantly limited rotation angle (higher aoa=more lift) really does impede it versus the A320 during takeoff. Assuming 75t TOW, depending on flap config, the 737 requires a 10-15knots higher vr than the A320. You need more runway to reach that higher takeoff speed (well duh!). Look it up in the performance charts if you don't believe me. FPPMs, AFMs and FCOMs have all the information you need. Even with isa+25 temps where I work, the A320 is rarely field limited.

The A320s performance really is quite remarkable when you take into account the 80s design wing. Those BAE wing designers knew a thing or two about field performance and they put the experience garnered through the A300 development into the A320.


All valid points, and I'm sure you have more experience than I do regarding 320 takeoff performance. I will admit that I'd be interested in seeing the difference in takeoff distance for the two types when loaded to the same *payload* instead of the same weight. It would seem to me that a 738 loaded to 75t is actually more loaded a bit more heavily (read: more pax and bags) than a 75t A320, mainly because the aforementioned heavier OEW of the Airbus (and it stands to reason that a more heavily loaded airplane will need a bit more runway...well, duh :mrgreen: ). A comparison of the two airplanes both loaded with the same amount of pax and fuel would be interesting (I'll admit that I don't have access to the kind of data needed to put together such an analysis). It's a bit of a moot point, especially since there are very few routes that actually utilize the full performance characteristics of either one of these rather capable airplanes.
"One test is worth a thousand expert opinions" -Tex Johnston
 
T54A
Posts: 124
Joined: Mon Oct 19, 2015 11:47 am

Re: Narrow body hot and high performance

Fri Apr 06, 2018 5:30 am

There is no simple answer to this. The Boeing might be using a lower flap setting (5) on the day which would have a longer ground roll but improved climb. I have flown A319's and when I sat in the jumpseat of a full B738 out of JNB the other day, I was very impressed with climb performance. Homesick angle was the thought I had. Both machines would be using max Assumed/Flex Temp, so you will never really get a true idea of what machine is capable of.
T6, Allouette 3, Oryx, King Air, B1900, B727, B744, A319, A342/3/6 A332/3
 
grjplanes
Posts: 147
Joined: Thu Oct 27, 2005 5:52 am

Re: Narrow body hot and high performance

Fri Apr 06, 2018 7:27 am

MIflyer12 wrote:
OP should, at least once, experience the take-off of a fairly empty 757 on that route. Zippy!


Maybe there's a specific reason why we don't really see 757 operations in South Africa...?

Interesting topic though, especially as it's pretty much a good comparison, both types on the exact same route out of JNB. Having watched countless take-offs at JNB it's quite interesting to see the longer take-off rolls of the 737-800s...even on shorter sectors like JNB-DUR.

The Air Zimbabwe 767-200ER usually looks to me to have a much shorter take-off roll and steep climb, of course on short JNB-HRE route...and I guess it's mostly fairly empty also
 
Chaostheory
Posts: 1080
Joined: Wed Mar 06, 2013 2:09 am

Re: Narrow body hot and high performance

Fri Apr 06, 2018 8:29 am

grjplanes wrote:
MIflyer12 wrote:
OP should, at least once, experience the take-off of a fairly empty 757 on that route. Zippy!


Maybe there's a specific reason why we don't really see 757 operations in South Africa...?

Interesting topic though, especially as it's pretty much a good comparison, both types on the exact same route out of JNB. Having watched countless take-offs at JNB it's quite interesting to see the longer take-off rolls of the 737-800s...even on shorter sectors like JNB-DUR.

The Air Zimbabwe 767-200ER usually looks to me to have a much shorter take-off roll and steep climb, of course on short JNB-HRE route...and I guess it's mostly fairly empty also


The 757 was redundant with the A300 already in SAA's fleet. Just as good a performer but a much more versatile aircraft.

You have to remember flaps are very draggy and their use restricts climb performance. The 762 is, as far as I know, the only Boeing jet approved for zero flap takeoff.
 
BoeingGuy
Posts: 5363
Joined: Fri Dec 10, 2010 6:01 pm

Re: Narrow body hot and high performance

Fri Apr 06, 2018 4:22 pm

Chaostheory wrote:
grjplanes wrote:
MIflyer12 wrote:
OP should, at least once, experience the take-off of a fairly empty 757 on that route. Zippy!


Maybe there's a specific reason why we don't really see 757 operations in South Africa...?

Interesting topic though, especially as it's pretty much a good comparison, both types on the exact same route out of JNB. Having watched countless take-offs at JNB it's quite interesting to see the longer take-off rolls of the 737-800s...even on shorter sectors like JNB-DUR.

The Air Zimbabwe 767-200ER usually looks to me to have a much shorter take-off roll and steep climb, of course on short JNB-HRE route...and I guess it's mostly fairly empty also


The 757 was redundant with the A300 already in SAA's fleet. Just as good a performer but a much more versatile aircraft.

You have to remember flaps are very draggy and their use restricts climb performance. The 762 is, as far as I know, the only Boeing jet approved for zero flap takeoff.


I think you mean the Flaps 1 setting, which is leading edge slats only. Flaps 0 is Flaps and slats up. However, you are correct about the 762. Someone posted recently that the 757-200 was also approved for Flaps 1 takeoff, but the 767-200 is like you mention.

Remember the 737 can do both assumed temperature and fix derate takeoffs. I wouldn’t draw conclusions about airplane performance based on takeoff roll. They could be doing a higher derate.

The 737-800 has no problem getting off SNA’s short runway and then flying to SEA or ORD so it’s a pretty good performer.
 
Ryanair01
Posts: 282
Joined: Fri Dec 27, 2013 9:27 pm

Re: Narrow body hot and high performance

Sat Apr 14, 2018 8:28 pm

The 737-800 has a larger than normal tail strike risk because of the stretch fuselage and low landing gear, which requires a slower more shallow rotation. That means you need to be going faster, which equals more runway. At a low level airport like SNA it makes very little difference, but at somewhere like JNB which is hot and high the impact is somewhat exaggerated.

Who is online

Users browsing this forum: BravoOne, EYKD, zknzf and 16 guests

Popular Searches On Airliners.net

Top Photos of Last:   24 Hours  •  48 Hours  •  7 Days  •  30 Days  •  180 Days  •  365 Days  •  All Time

Military Aircraft Every type from fighters to helicopters from air forces around the globe

Classic Airliners Props and jets from the good old days

Flight Decks Views from inside the cockpit

Aircraft Cabins Passenger cabin shots showing seat arrangements as well as cargo aircraft interior

Cargo Aircraft Pictures of great freighter aircraft

Government Aircraft Aircraft flying government officials

Helicopters Our large helicopter section. Both military and civil versions

Blimps / Airships Everything from the Goodyear blimp to the Zeppelin

Night Photos Beautiful shots taken while the sun is below the horizon

Accidents Accident, incident and crash related photos

Air to Air Photos taken by airborne photographers of airborne aircraft

Special Paint Schemes Aircraft painted in beautiful and original liveries

Airport Overviews Airport overviews from the air or ground

Tails and Winglets Tail and Winglet closeups with beautiful airline logos