Moderators: richierich, ua900, PanAm_DC10, hOMSaR

 
AC320tech
Topic Author
Posts: 208
Joined: Mon Jul 31, 2006 6:32 am

The Long Range Playbook

Mon Sep 21, 2020 9:16 pm

Am I on the right path to thinking here about long range aircraft? I'm trying to figure out the correlation between high thrust engines and a range increase. For Airbus X models and Boeing ER or LR models Ive noticed that the MTOW and engine thrust ratings are higher than the base, non X, ER, or LR models.

Take the 777-200LR for example. The aircraft gets rewinged, reengined, structural changes, and an MTOW boost. Does the engines higher thrust work with the structural change to increase the MTOW to allow for a better fuel/payload trade-off? Do the higher thrust engines enable the aircrafts climb performance to be better, getting it to cruise altitude faster? And with the higher thrust engines, does this enable the aircraft to climb to a higher altitude right away as opposed to step climbing? Or even the 767-200 vs -200ER, the ER has higher thrust engines and higher MTOW, with the higher thrust does this allow for an MTOW increase making more room for fuel weight while the revenue payload can stay the same and thus increasing range?

Is there anything I'm missing about the correlation of high thrust to range increase?
 
GalaxyFlyer
Posts: 8070
Joined: Fri Jan 01, 2016 4:44 am

Re: The Long Range Playbook

Mon Sep 21, 2020 10:33 pm

Higher thrust will increase climb rate, but not the wing.’s optimum altitude based on TOGW minus climb burn. See B777-300 optimum level after cross weight take-off.
 
EssentialPowr
Posts: 1732
Joined: Wed Sep 06, 2000 10:30 pm

Re: The Long Range Playbook

Mon Sep 21, 2020 11:54 pm

Thrust ratings typically correlate with MGTOWs. Heavier MGTOW, more thrust capability. That effectively keeps the thrust to weight ratio constant over the sub variant range of weights, thought most operators tend to select heavier variants as they are developed. The GE90s on the original Continental 777-200s were delivered “set” at 90000 lb thrust, and have been bumped up to I believe the max at 115000 lbs to maximize range and payload. Big check to GE, big bump in capability.
 
User avatar
77west
Posts: 1015
Joined: Sat Jun 13, 2009 11:52 am

Re: The Long Range Playbook

Tue Sep 22, 2020 12:59 am

EssentialPowr wrote:
Thrust ratings typically correlate with MGTOWs. Heavier MGTOW, more thrust capability. That effectively keeps the thrust to weight ratio constant over the sub variant range of weights, thought most operators tend to select heavier variants as they are developed. The GE90s on the original Continental 777-200s were delivered “set” at 90000 lb thrust, and have been bumped up to I believe the max at 115000 lbs to maximize range and payload. Big check to GE, big bump in capability.


While it is true you can have a range of thrust options for the same engine; the GE90 on the 777-200 and -200ER is not the same engine as the GE90-115B on the -300ER and -200LR

It was derived from it but is bigger and has different internals and fan.
77West - AW109S - BE90 - JS31 - B1900 - Q300 - ATR72 - DC9-30 - MD80 - B733 - A320 - B738 - A300-B4 - B773 - B77W
 
EssentialPowr
Posts: 1732
Joined: Wed Sep 06, 2000 10:30 pm

Re: The Long Range Playbook

Tue Sep 22, 2020 1:18 am

77west wrote:
EssentialPowr wrote:
Thrust ratings typically correlate with MGTOWs. Heavier MGTOW, more thrust capability. That effectively keeps the thrust to weight ratio constant over the sub variant range of weights, thought most operators tend to select heavier variants as they are developed. The GE90s on the original Continental 777-200s were delivered “set” at 90000 lb thrust, and have been bumped up to I believe the max at 115000 lbs to maximize range and payload. Big check to GE, big bump in capability.


While it is true you can have a range of thrust options for the same engine; the GE90 on the 777-200 and -200ER is not the same engine as the GE90-115B on the -300ER and -200LR

It was derived from it but is bigger and has different internals and fan.


Different thrust ratings for different dash numbers of the same parent core is jet engine 101. The -94B vs -115B follow suit. The Cal 777-200s were bumped from 90000; not sure what the current PIP ratings are for the -94B. Specific values are negotiated on a per customer basis.
 
gloom
Posts: 558
Joined: Thu Jun 30, 2016 4:24 pm

Re: The Long Range Playbook

Tue Sep 22, 2020 5:14 am

As a short introduction, and a checklist to what affects what. Order of items matters.
For takeoff performance, you need thrust and wing area (or generally aero as a whole, if it's different to wing-and-tube)
For climb gradient you need wing and thrust (except for rare occasions when one engine fails)
For climb to cruise you need aero and thrust
For cruise, all you need is aero efficiency; modern engines have excess thrust at altitude

So, taking that back to OP question.
The lane is always trade-off - it never can take all payload and fuel into air. You need to trade fuel for payload or payload for fuel.
Back in the old days, more powerful engines managed to take more weight in the air, that raised range (for increased weight cost). See A330 classics, 777 for examples.
Last generation planes take advantage of bigger, better wing. See Boeings 787s, 777X, or Airbuses 330neo, 350. This allows them ULR with similar payload but at lower weights* and with less fuel.
Of course, this is as simple as possible, and as such it utilizes some not-so-true statements. They are here simply to avoid going too technical or over-detailed for simple understanding, please try not to prove I'm wrong. I know I am at some statements, and know exatly why. :)

Cheers, Adam

* neo/X are a bit different, since they are rebuilds of existing desings.
 
flipdewaf
Posts: 4168
Joined: Thu Jul 20, 2006 6:28 am

Re: The Long Range Playbook

Tue Sep 22, 2020 9:21 am

In a very basic sense, the further you want to fly the longer it will take you and staying in the air longer requires more fuel. Fuel weighs and so you need to add that to the weight of the aircraft hence your aircraft gets heavier.
If your aircraft is heavier it needs more thrust to stay in the air and also needs more thrust to get it up to the speed where it can fly.

Fred
Image
 
User avatar
77west
Posts: 1015
Joined: Sat Jun 13, 2009 11:52 am

Re: The Long Range Playbook

Wed Sep 23, 2020 12:40 am

EssentialPowr wrote:
77west wrote:
EssentialPowr wrote:
Thrust ratings typically correlate with MGTOWs. Heavier MGTOW, more thrust capability. That effectively keeps the thrust to weight ratio constant over the sub variant range of weights, thought most operators tend to select heavier variants as they are developed. The GE90s on the original Continental 777-200s were delivered “set” at 90000 lb thrust, and have been bumped up to I believe the max at 115000 lbs to maximize range and payload. Big check to GE, big bump in capability.


While it is true you can have a range of thrust options for the same engine; the GE90 on the 777-200 and -200ER is not the same engine as the GE90-115B on the -300ER and -200LR

It was derived from it but is bigger and has different internals and fan.


Different thrust ratings for different dash numbers of the same parent core is jet engine 101. The -94B vs -115B follow suit. The Cal 777-200s were bumped from 90000; not sure what the current PIP ratings are for the -94B. Specific values are negotiated on a per customer basis.


The 90-94B and -115B are not the same engine... if thats what you were implying. The 90-90B and 90-94B are indeed a thrust plug change, as is the -110B and -115B. But you cant bump a -90B up to a -115B
77West - AW109S - BE90 - JS31 - B1900 - Q300 - ATR72 - DC9-30 - MD80 - B733 - A320 - B738 - A300-B4 - B773 - B77W
 
EssentialPowr
Posts: 1732
Joined: Wed Sep 06, 2000 10:30 pm

Re: The Long Range Playbook

Wed Sep 23, 2020 1:45 am

77west wrote:
EssentialPowr wrote:
77west wrote:

While it is true you can have a range of thrust options for the same engine; the GE90 on the 777-200 and -200ER is not the same engine as the GE90-115B on the -300ER and -200LR

It was derived from it but is bigger and has different internals and fan.


Different thrust ratings for different dash numbers of the same parent core is jet engine 101. The -94B vs -115B follow suit. The Cal 777-200s were bumped from 90000; not sure what the current PIP ratings are for the -94B. Specific values are negotiated on a per customer basis.


The 90-94B and -115B are not the same engine... if thats what you were implying. The 90-90B and 90-94B are indeed a thrust plug change, as is the -110B and -115B. But you cant bump a -90B up to a -115B


That’s why I noted “-94B VS -115B”; different cores. My guess is that there is a PIP coming for the -90B that takes it above 94000, as that particular PIP was from 2003, and aircraft get heavier as they age, and any thrust bumps are always beneficial from a performance standpoint if the costs can be justified.
 
User avatar
77west
Posts: 1015
Joined: Sat Jun 13, 2009 11:52 am

Re: The Long Range Playbook

Wed Sep 23, 2020 10:05 am

EssentialPowr wrote:
77west wrote:
EssentialPowr wrote:

Different thrust ratings for different dash numbers of the same parent core is jet engine 101. The -94B vs -115B follow suit. The Cal 777-200s were bumped from 90000; not sure what the current PIP ratings are for the -94B. Specific values are negotiated on a per customer basis.


The 90-94B and -115B are not the same engine... if thats what you were implying. The 90-90B and 90-94B are indeed a thrust plug change, as is the -110B and -115B. But you cant bump a -90B up to a -115B


That’s why I noted “-94B VS -115B”; different cores. My guess is that there is a PIP coming for the -90B that takes it above 94000, as that particular PIP was from 2003, and aircraft get heavier as they age, and any thrust bumps are always beneficial from a performance standpoint if the costs can be justified.


A PIP for the older GE90-90/94B? Why? It could probably manage 98,000 or even 100,000 technically but given no more of the 777 with this engine are on order or available, and there were not that many -200/200ER that used it, why would they PIP it? Certainly for long range, the -110/115 family has proved it worth on the models that use it.
77West - AW109S - BE90 - JS31 - B1900 - Q300 - ATR72 - DC9-30 - MD80 - B733 - A320 - B738 - A300-B4 - B773 - B77W
 
GalaxyFlyer
Posts: 8070
Joined: Fri Jan 01, 2016 4:44 am

Re: The Long Range Playbook

Wed Sep 23, 2020 2:19 pm

Look up Breguet range formula, range is a function of fuel fraction, the ratio of fuel weight to gross weight. More fuel, more weight more thrust AND aerodynamics required.you have to maintain controllability with that increased thrust.
 
EssentialPowr
Posts: 1732
Joined: Wed Sep 06, 2000 10:30 pm

Re: The Long Range Playbook

Wed Sep 23, 2020 3:45 pm

77west wrote:


A PIP for the older GE90-90/94B? Why? It could probably manage 98,000 or even 100,000 technically but given no more of the 777 with this engine are on order or available, and there were not that many -200/200ER that used it, why would they PIP it? Certainly for long range, the -110/115 family has proved it worth on the models that use it.


A thrust bump would enable those a/c to fully maximize payload on long flights. That’s what drives the PIP in the first place, particularly with the emphasis on cargo with lighter pax loads at the moment. Don’t know how the new interiors compare in weight to the new aircraft, but airframes only get heavier with age. As I stated, more thrust capability is always an asset if it can be obtained at a reasonable cost. The additional temp capability of the thrust increase can also be conversely used to increase time on wing by retaining the previous thrust level while operating with wider temp margins provided by the new upper temperature limit.

How much thrust can be installed on those aircraft from a single engine perspective becomes an issue, but I’m guessing there’s sufficient margin for 100,000 lbs thrust per engine...
Last edited by EssentialPowr on Wed Sep 23, 2020 4:11 pm, edited 1 time in total.
 
flipdewaf
Posts: 4168
Joined: Thu Jul 20, 2006 6:28 am

Re: The Long Range Playbook

Thu Sep 24, 2020 2:10 am

EssentialPowr wrote:
Pls delete above 2 posts....

Flip, I’m good with everything I’m said. It’s all there, I don’t think you are what you claim. Technical people can typically write technically,
I can but it doesn’t come naturally to me, I tend, in my current role (I work in research) to communicate via presentation if I can. I am a story teller.
EssentialPowr wrote:
and I think you have a gross conceptual error about part 121 takeoff performance,
what do you think my error is?

I don’t know the regs per se, when we were doing performance calculations on designs at uni we used the Stamford course notes (which I guess were based on part121? ) but I did my degree in the UK and so there may have been differences. The performance calcs done were based on acc-stop and acc-go to determine balanced field. Minimum control speed for engine out for both aerodynamic direction control (rudder) and from the tyres. Of course there is wind and the addition of rotation times and climb to screen height ( which for some reason was 35ft ...except when it was50....) acc distance + rotate distance + transition distance + climb to screen heigh .

Interestingly when going through the control sizing I was shocked at how regularly the cross wind landing limitation came as the sizing factor on the tail.

Once it’s finished the takeoff phase the climb out needs to occur with one engine inop. Not sure if this is still the case in the regs but my notes have differing requirements based on number if engines. 2.4% being the climb gradient for a 4 engine aircraft, always seemed weird that the requirements were different based on number of engines.

Of course added to that there is local cinditions: wind, temp, density. In the world of fundamental calculations for these things they can be derived from various ISA tables/models. I have a ISA + 0 table I use for my performance models, I have toyed with the idea of deriving it so that deviations can be modelled.

I have mentioned in the past that I would like to add a takeoff performance calculator to my model so it’s probably worth looking back at my notes.

EssentialPowr wrote:
particularly if you are the guy claiming what makes it safe out not.... with absolute ZERO parameters defined.
seeing as the parameters required are proprietary information should that stop a discussion? Or should we make reasonable guesses?
EssentialPowr wrote:
Do I think I know more that you? Yep. (Just trying to help answer your questions!)

so you assume you know more than me just like you believe I assume I know more than YouTube fanboys? Interesting...
EssentialPowr wrote:

Want to chat about CRM now? Love to hear a YouTube fanboy!
Then go to YouTube.

My limit on CRM is what it means and why it’s implemented ( it should be implemented in more offices) I have not used it in practice or have more than a rudimentary understanding, I have to say it doesn’t interest me that much.

Fred


Sent from my iPhone using Tapatalk
Image
 
flipdewaf
Posts: 4168
Joined: Thu Jul 20, 2006 6:28 am

Re: The Long Range Playbook

Thu Sep 24, 2020 2:11 am

EssentialPowr wrote:
Pls delete above 2 posts....

Flip, I’m good with everything I’m said. It’s all there, I don’t think you are what you claim. Technical people can typically write technically,
I can but it doesn’t come naturally to me, I tend, in my current role (I work in research) to communicate via presentation if I can. I am a story teller.
EssentialPowr wrote:
and I think you have a gross conceptual error about part 121 takeoff performance,
what do you think my error is?

I don’t know the regs per se, when we were doing performance calculations on designs at uni we used the Stamford course notes (which I guess were based on part121? ) but I did my degree in the UK and so there may have been differences. The performance calcs done were based on acc-stop and acc-go to determine balanced field. Minimum control speed for engine out for both aerodynamic direction control (rudder) and from the tyres. Of course there is wind and the addition of rotation times and climb to screen height ( which for some reason was 35ft ...except when it was50....) acc distance + rotate distance + transition distance + climb to screen heigh .

Interestingly when going through the control sizing I was shocked at how regularly the cross wind landing limitation came as the sizing factor on the tail.

Once it’s finished the takeoff phase the climb out needs to occur with one engine inop. Not sure if this is still the case in the regs but my notes have differing requirements based on number if engines. 2.4% being the climb gradient for a 4 engine aircraft, always seemed weird that the requirements were different based on number of engines.

Of course added to that there is local cinditions: wind, temp, density. In the world of fundamental calculations for these things they can be derived from various ISA tables/models. I have a ISA + 0 table I use for my performance models, I have toyed with the idea of deriving it so that deviations can be modelled.

I have mentioned in the past that I would like to add a takeoff performance calculator to my model so it’s probably worth looking back at my notes.

EssentialPowr wrote:
particularly if you are the guy claiming what makes it safe out not.... with absolute ZERO parameters defined.
seeing as the parameters required are proprietary information should that stop a discussion? Or should we make reasonable guesses?
EssentialPowr wrote:
Do I think I know more that you? Yep. (Just trying to help answer your questions!)

so you assume you know more than me just like you believe I assume I know more than YouTube fanboys? Interesting...
EssentialPowr wrote:

Want to chat about CRM now? Love to hear a YouTube fanboy!
Then go to YouTube.

My limit on CRM is what it means and why it’s implemented ( it should be implemented in more offices) I have not used it in practice or have more than a rudimentary understanding, I have to say it doesn’t interest me that much.

Fred


Sent from my iPhone using Tapatalk
Image
 
flipdewaf
Posts: 4168
Joined: Thu Jul 20, 2006 6:28 am

Re: The Long Range Playbook

Thu Sep 24, 2020 2:11 am

EssentialPowr wrote:
Pls delete above 2 posts....

Flip, I’m good with everything I’m said. It’s all there, I don’t think you are what you claim. Technical people can typically write technically,
I can but it doesn’t come naturally to me, I tend, in my current role (I work in research) to communicate via presentation if I can. I am a story teller.
EssentialPowr wrote:
and I think you have a gross conceptual error about part 121 takeoff performance,
what do you think my error is?

I don’t know the regs per se, when we were doing performance calculations on designs at uni we used the Stamford course notes (which I guess were based on part121? ) but I did my degree in the UK and so there may have been differences. The performance calcs done were based on acc-stop and acc-go to determine balanced field. Minimum control speed for engine out for both aerodynamic direction control (rudder) and from the tyres. Of course there is wind and the addition of rotation times and climb to screen height ( which for some reason was 35ft ...except when it was50....) acc distance + rotate distance + transition distance + climb to screen heigh .

Interestingly when going through the control sizing I was shocked at how regularly the cross wind landing limitation came as the sizing factor on the tail.

Once it’s finished the takeoff phase the climb out needs to occur with one engine inop. Not sure if this is still the case in the regs but my notes have differing requirements based on number if engines. 2.4% being the climb gradient for a 4 engine aircraft, always seemed weird that the requirements were different based on number of engines.

Of course added to that there is local cinditions: wind, temp, density. In the world of fundamental calculations for these things they can be derived from various ISA tables/models. I have a ISA + 0 table I use for my performance models, I have toyed with the idea of deriving it so that deviations can be modelled.

I have mentioned in the past that I would like to add a takeoff performance calculator to my model so it’s probably worth looking back at my notes.

EssentialPowr wrote:
particularly if you are the guy claiming what makes it safe out not.... with absolute ZERO parameters defined.
seeing as the parameters required are proprietary information should that stop a discussion? Or should we make reasonable guesses?
EssentialPowr wrote:
Do I think I know more that you? Yep. (Just trying to help answer your questions!)

so you assume you know more than me just like you believe I assume I know more than YouTube fanboys? Interesting...
EssentialPowr wrote:

Want to chat about CRM now? Love to hear a YouTube fanboy!
Then go to YouTube.

My limit on CRM is what it means and why it’s implemented ( it should be implemented in more offices) I have not used it in practice or have more than a rudimentary understanding, I have to say it doesn’t interest me that much.

Fred


Sent from my iPhone using Tapatalk
Image
 
flipdewaf
Posts: 4168
Joined: Thu Jul 20, 2006 6:28 am

Re: The Long Range Playbook

Thu Sep 24, 2020 2:13 am

EssentialPowr wrote:
Pls delete above 2 posts....

Flip, I’m good with everything I’m said. It’s all there, I don’t think you are what you claim. Technical people can typically write technically,
I can but it doesn’t come naturally to me, I tend, in my current role (I work in research) to communicate via presentation if I can. I am a story teller.
EssentialPowr wrote:
and I think you have a gross conceptual error about part 121 takeoff performance,
what do you think my error is?

I don’t know the regs per se, when we were doing performance calculations on designs at uni we used the Stamford course notes (which I guess were based on part121? ) but I did my degree in the UK and so there may have been differences. The performance calcs done were based on acc-stop and acc-go to determine balanced field. Minimum control speed for engine out for both aerodynamic direction control (rudder) and from the tyres. Of course there is wind and the addition of rotation times and climb to screen height ( which for some reason was 35ft ...except when it was50....) acc distance + rotate distance + transition distance + climb to screen heigh .

Interestingly when going through the control sizing I was shocked at how regularly the cross wind landing limitation came as the sizing factor on the tail.

Once it’s finished the takeoff phase the climb out needs to occur with one engine inop. Not sure if this is still the case in the regs but my notes have differing requirements based on number if engines. 2.4% being the climb gradient for a 4 engine aircraft, always seemed weird that the requirements were different based on number of engines.

Of course added to that there is local cinditions: wind, temp, density. In the world of fundamental calculations for these things they can be derived from various ISA tables/models. I have a ISA + 0 table I use for my performance models, I have toyed with the idea of deriving it so that deviations can be modelled.

I have mentioned in the past that I would like to add a takeoff performance calculator to my model so it’s probably worth looking back at my notes.

EssentialPowr wrote:
particularly if you are the guy claiming what makes it safe out not.... with absolute ZERO parameters defined.
seeing as the parameters required are proprietary information should that stop a discussion? Or should we make reasonable guesses?
EssentialPowr wrote:
Do I think I know more that you? Yep. (Just trying to help answer your questions!)

so you assume you know more than me just like you believe I assume I know more than YouTube fanboys? Interesting...
EssentialPowr wrote:

Want to chat about CRM now? Love to hear a YouTube fanboy!
Then go to YouTube.

My limit on CRM is what it means and why it’s implemented ( it should be implemented in more offices) I have not used it in practice or have more than a rudimentary understanding, I have to say it doesn’t interest me that much.

Fred


Sent from my iPhone using Tapatalk
Image
 
EssentialPowr
Posts: 1732
Joined: Wed Sep 06, 2000 10:30 pm

Re: The Long Range Playbook

Mon Sep 28, 2020 1:01 am

Flipdewaf, from the “Boeing considering 757-plus and 767 x x” topic:

“Can you show it or is this conjecture based on all engines operating takeoffs witnessed?

With all engines operating and higher thrust the excess thrust is huge hence the meme about being a rocketship. However in the critical instance of one engine inoperative the higher span wise loading and high lift induced drag phase at takeoff means that this advantage is negated.

As the A321 is effectively limited by rotation angle at takeoff then the relatively high wing loading is of less importance to takeoff distance, the jet here is effective control of pitch and the FBW system of the A32x has allowed significant improvements to the ability to safely manage this to a higher angle.

The impact of the safety critical case is more limiting to the 757 than the A321 and personally I’m only flying airlines that calculate takeoff distances based on safety not fanboys wooping at YouTube videos.

Fred”

Your attempt to draw a conclusion on single engine performance with no parameters defined, referencing some terms in a disjointed fashion doesn’t prove anything let alone allow for comparison. As I mentioned previously, all part 121 takeoffs are predicated on an engine failure so if you’re “Only flying airlines that calculate distances based on safety” then you must not understand that concept to have attempted to make that point. If you don’t have access to performance data, picking out a couple of parameters to attempt to make a point is not even close to valid analysis.
 
flipdewaf
Posts: 4168
Joined: Thu Jul 20, 2006 6:28 am

Re: The Long Range Playbook

Mon Sep 28, 2020 6:07 am

Oh! So you’re saying one can not determine the takeoff performance from the information we have publicly available. So we cannot say that the 757 is better based on evidence such as YouTube, you are indeed proving point. Thanks.

Fred


Sent from my iPhone using Tapatalk
Image
 
EssentialPowr
Posts: 1732
Joined: Wed Sep 06, 2000 10:30 pm

Re: The Long Range Playbook

Mon Sep 28, 2020 6:26 am

flipdewaf wrote:
Oh! So you’re saying one can not determine the takeoff performance from the information we have publicly available. So we cannot say that the 757 is better based on evidence such as YouTube, you are indeed proving point. Thanks.

Fred

Sent from my iPhone using Tapatalk


So there was no point whatsoever to be made from your post? Hopefully it won’t get repeated 3 times?
Last edited by EssentialPowr on Mon Sep 28, 2020 6:42 am, edited 1 time in total.
 
flipdewaf
Posts: 4168
Joined: Thu Jul 20, 2006 6:28 am

Re: The Long Range Playbook

Mon Sep 28, 2020 6:30 am

The fact that you didn’t understand it is neither here nor there as to whether actually just explained it well. M
Thanks.


Sent from my iPhone using Tapatalk
Image
 
EssentialPowr
Posts: 1732
Joined: Wed Sep 06, 2000 10:30 pm

Re: The Long Range Playbook

Mon Sep 28, 2020 6:34 am

flipdewaf wrote:
The fact that you didn’t understand it is neither here nor there as to whether actually just explained it well. M
Thanks.


Sent from my iPhone using Tapatalk


Ok, just explain Your comment: “The impact of the safety critical case is more limiting to the 757 than the A321 and personally I’m only flying airlines that calculate takeoff distances based on safety not fanboys wooping at YouTube videos.”

What?? Can you prove your statement? Do we need to alert Boeing to issue an AD on the 757 for a larger vertical tail? How did you validate your claim? What exactly is a “safety critical case”, and once you figure that out, how is the 757 “more limiting” than the A321? Did you inform the 757 operators about your claim? How was the 757 design robust enough to have blended winglets added, as it relates to span wise flow, and certainly bending moments?
 
flipdewaf
Posts: 4168
Joined: Thu Jul 20, 2006 6:28 am

Re: The Long Range Playbook

Mon Sep 28, 2020 2:14 pm

EssentialPowr wrote:
flipdewaf wrote:
The fact that you didn’t understand it is neither here nor there as to whether actually just explained it well. M
Thanks.


Sent from my iPhone using Tapatalk


Ok, just explain Your comment: “The impact of the safety critical case is more limiting to the 757 than the A321 and personally I’m only flying airlines that calculate takeoff distances based on safety not fanboys wooping at YouTube videos.”

What?? Can you prove your statement? Do we need to alert Boeing to issue an AD on the 757 for a larger vertical tail? How did you validate your claim? What exactly is a “safety critical case”, and once you figure that out, how is the 757 “more limiting” than the A321? Did you inform the 757 operators about your claim? How was the 757 design robust enough to have blended winglets added, as it relates to span wise flow, and certainly bending moments?


Wow, maybe you should ask that in the actual thread...

Fred
Image
 
EssentialPowr
Posts: 1732
Joined: Wed Sep 06, 2000 10:30 pm

Re: The Long Range Playbook

Mon Sep 28, 2020 3:11 pm

flipdewaf wrote:

Wow, maybe you should ask that in the actual thread...

Fred


You had mentioned in This thread before it was deleted that I should review any of your postings if I had questions, so I did as you asked.

An explanation of your comment: “The impact of the safety critical case is more limiting to the 757 than the A321 and personally I’m only flying airlines that calculate takeoff distances based on safety not fanboys wooping at YouTube videos.”

IS valid, per your request.
 
User avatar
kitplane01
Posts: 1905
Joined: Thu Jun 16, 2016 5:58 am

Re: The Long Range Playbook

Wed Sep 30, 2020 5:06 am

In a mathematical sense, range is a formula based on fuel fraction, lift/drag ratio, etc.

But I was under the impression that it was easier for planes to get a higher lift/drag ratio at higher speeds in thinner air. That's *why* airliners climb so high. And bigger engines can produce the same thrust at higher altitude in thinner air.
 
gloom
Posts: 558
Joined: Thu Jun 30, 2016 4:24 pm

Re: The Long Range Playbook

Wed Sep 30, 2020 6:12 am

kitplane01 wrote:
In a mathematical sense, range is a formula based on fuel fraction, lift/drag ratio, etc.

But I was under the impression that it was easier for planes to get a higher lift/drag ratio at higher speeds in thinner air. That's *why* airliners climb so high. And bigger engines can produce the same thrust at higher altitude in thinner air.


Well, not really. Again, simplified since I don't want the math to kick in too much.

The plane cruises in the air. Let's assume we have an idea to go all the way on constant indicated, where lift to drag is optimum. The higher you go, you keep speed to air at optimum. However, since you go in thinner air, the speed to reference outside will increase, as you need to go faster to maintain dynamic pressure on wings and speedometer. Thta's roughly the difference between IAS and TAS. It's worth 2% (more or less) every 1.000ft. And it's working up until the point where Mach effects kick in (you go constant Mach from that point).

You are not right in pointing out same thrust from engines at higher. The amount of thrust is more or less equal to amount of fuel and air (since they're used to prduce thrust). When going higher, the thrust also reduces, since air flow is also reduced. There used to be Java applet available where different engines were simulated, I remember going over CFM56 rated 23.500lbs sea level. At 737CL max altitude (F370) there was something like 5700 lbs remaining. So, the altitude affects engines quite much.

Since the drag at high is lower, you don't need full thrust. You only need minimal excess to maintain speed (wind change etc) at altitude, while most of takeoff thrust is to accelerate/climb out. Plus, higher-bypass engines seem to have higher thrust at altitude, giving same thrust at lower RPM.

So, to sum up: you get higher true/ground speed at same indicated airspeed when flying higher. The engine will use more or less same thrust and fuel flow to maintain same indicated. You will have enough thrust to maintain speed at altitude, since drag at altitude will be significantly lower, thus offseting lower thrust produced.

Yeah, as simple as it gets. Hope I nailed it.

Cheers,
Adam

PS. For a given frame (and weight, and a little more), you have an optimum IAS speed, where lift to drag is optimum. You would want to be as close to that optimum speed, when going for a range/minimum costs. In most conditions, the plane will go a bit faster, to offset with time spent on route. But the speeds mentioned above will be more-or-less the same for a given type.
 
flipdewaf
Posts: 4168
Joined: Thu Jul 20, 2006 6:28 am

Re: The Long Range Playbook

Wed Sep 30, 2020 10:21 am

EssentialPowr wrote:
flipdewaf wrote:

Wow, maybe you should ask that in the actual thread...

Fred


You had mentioned in This thread before it was deleted that I should review any of your postings if I had questions, so I did as you asked.

An explanation of your comment: “The impact of the safety critical case is more limiting to the 757 than the A321 and personally I’m only flying airlines that calculate takeoff distances based on safety not fanboys wooping at YouTube videos.”

IS valid, per your request.


oh ok.

The excess thrust available per unit weight compared to the A321 in normal day to day operations (all engines operating) is is negated more than it is with the A321 when when calculating using the one engine inoperative case.
i.e. the difference between available thrust and drag divided by the weight is greater in the one engine vs two engines operating scenario in the 757 than it is in the A321 at their estimated climb out speeds. This is primarily due to wing geometries.

If you would like to read more then please see the Aircraft Conceptual Design Synthesis from Cranfield university or Aircraft Design:Synthesis and Analysis from Stamford university.

gloom wrote:
kitplane01 wrote:
In a mathematical sense, range is a formula based on fuel fraction, lift/drag ratio, etc.

But I was under the impression that it was easier for planes to get a higher lift/drag ratio at higher speeds in thinner air. That's *why* airliners climb so high. And bigger engines can produce the same thrust at higher altitude in thinner air.


Well, not really. Again, simplified since I don't want the math to kick in too much.

The plane cruises in the air. Let's assume we have an idea to go all the way on constant indicated, where lift to drag is optimum. The higher you go, you keep speed to air at optimum. However, since you go in thinner air, the speed to reference outside will increase, as you need to go faster to maintain dynamic pressure on wings and speedometer. Thta's roughly the difference between IAS and TAS. It's worth 2% (more or less) every 1.000ft. And it's working up until the point where Mach effects kick in (you go constant Mach from that point).

You are not right in pointing out same thrust from engines at higher. The amount of thrust is more or less equal to amount of fuel and air (since they're used to prduce thrust). When going higher, the thrust also reduces, since air flow is also reduced. There used to be Java applet available where different engines were simulated, I remember going over CFM56 rated 23.500lbs sea level. At 737CL max altitude (F370) there was something like 5700 lbs remaining. So, the altitude affects engines quite much.

Since the drag at high is lower, you don't need full thrust. You only need minimal excess to maintain speed (wind change etc) at altitude, while most of takeoff thrust is to accelerate/climb out. Plus, higher-bypass engines seem to have higher thrust at altitude, giving same thrust at lower RPM.

So, to sum up: you get higher true/ground speed at same indicated airspeed when flying higher. The engine will use more or less same thrust and fuel flow to maintain same indicated. You will have enough thrust to maintain speed at altitude, since drag at altitude will be significantly lower, thus offseting lower thrust produced.

Yeah, as simple as it gets. Hope I nailed it.

Cheers,
Adam

PS. For a given frame (and weight, and a little more), you have an optimum IAS speed, where lift to drag is optimum. You would want to be as close to that optimum speed, when going for a range/minimum costs. In most conditions, the plane will go a bit faster, to offset with time spent on route. But the speeds mentioned above will be more-or-less the same for a given type.


When I was at uni one of the lecturers explained that the way he likes to think about why airliners fly high is that it isn't to do with drag so much as it is speed (its all connected of course but bear with me).
You can fly at the same drag at low altitudes as you can at high altitudes, its just that when you do it at high altitudes you go faster/further whilst doing it. I find it a useful way to think of it because whilst to a certain degree drag might be the enemy the goal is more about specific range.

Fred
Image
 
gloom
Posts: 558
Joined: Thu Jun 30, 2016 4:24 pm

Re: The Long Range Playbook

Wed Sep 30, 2020 11:02 am

Fred,

I was thinking among same lines. TAS increase in high, or lower drag in high (at same TAS) are two ways of thinking about very same physics. Simplified, and both need to be separate (either describe speed increase, or drag - not both, and I seem to have failed that separation above) but true enough.

Cheers,
Adam
 
User avatar
kitplane01
Posts: 1905
Joined: Thu Jun 16, 2016 5:58 am

Re: The Long Range Playbook

Wed Sep 30, 2020 7:49 pm

gloom wrote:
kitplane01 wrote:
In a mathematical sense, range is a formula based on fuel fraction, lift/drag ratio, etc.

But I was under the impression that it was easier for planes to get a higher lift/drag ratio at higher speeds in thinner air. That's *why* airliners climb so high. And bigger engines can produce the same thrust at higher altitude in thinner air.


Well, not really. Again, simplified since I don't want the math to kick in too much.

The plane cruises in the air. Let's assume we have an idea to go all the way on constant indicated, where lift to drag is optimum. The higher you go, you keep speed to air at optimum. However, since you go in thinner air, the speed to reference outside will increase, as you need to go faster to maintain dynamic pressure on wings and speedometer. Thta's roughly the difference between IAS and TAS. It's worth 2% (more or less) every 1.000ft. And it's working up until the point where Mach effects kick in (you go constant Mach from that point).

You are not right in pointing out same thrust from engines at higher. The amount of thrust is more or less equal to amount of fuel and air (since they're used to prduce thrust). When going higher, the thrust also reduces, since air flow is also reduced. There used to be Java applet available where different engines were simulated, I remember going over CFM56 rated 23.500lbs sea level. At 737CL max altitude (F370) there was something like 5700 lbs remaining. So, the altitude affects engines quite much.

Since the drag at high is lower, you don't need full thrust. You only need minimal excess to maintain speed (wind change etc) at altitude, while most of takeoff thrust is to accelerate/climb out. Plus, higher-bypass engines seem to have higher thrust at altitude, giving same thrust at lower RPM.

So, to sum up: you get higher true/ground speed at same indicated airspeed when flying higher. The engine will use more or less same thrust and fuel flow to maintain same indicated. You will have enough thrust to maintain speed at altitude, since drag at altitude will be significantly lower, thus offseting lower thrust produced.

Yeah, as simple as it gets. Hope I nailed it.

Cheers,
Adam

PS. For a given frame (and weight, and a little more), you have an optimum IAS speed, where lift to drag is optimum. You would want to be as close to that optimum speed, when going for a range/minimum costs. In most conditions, the plane will go a bit faster, to offset with time spent on route. But the speeds mentioned above will be more-or-less the same for a given type.


Consider two engines. (1) can produce 20,000 lbs thrust and (2) can produce 30,000 lbs thrust. Given equivalent technology and such, (2) is able to ingest 50% more air. Now suppose that we only want 10,000 lbs thrust, engine (2) can do so in a less dense atmosphere. Both engines require about the same weight of air, but (2) can ingest more volume of air because it's a bigger engine.

And then (as others have said) if your cruise at a constant indicated air speed, but at a higher true air speed (because thinner air) you will go further per unit of fuel.



hey are able to consume enough air even at lower air densities.
 
EssentialPowr
Posts: 1732
Joined: Wed Sep 06, 2000 10:30 pm

Re: The Long Range Playbook

Thu Oct 01, 2020 1:06 am

flipdewaf wrote:
EssentialPowr wrote:
flipdewaf wrote:

Wow, maybe you should ask that in the actual thread...

Fred


You had mentioned in This thread before it was deleted that I should review any of your postings if I had questions, so I did as you asked.

An explanation of your comment: (statement 1) “The impact of the safety critical case (what impact??) is more limiting (what limit??) to the 757 than the A321 and personally I’m only flying airlines that calculate takeoff distances based on safety (takeoff distances per Part 121 are based on many variables for each specific takeoff, Requiring all climb limits to be met for the particular conditions!) not fanboys wooping at YouTube videos.”

IS valid, per your request.


oh ok.

(Statement 2) The excess thrust available per unit weight compared to the A321 in normal day to day operations (all engines operating) is is negated more (“negated more?? What??) than it is with the A321 when when calculating using the one engine inoperative case.
i.e. the difference between available thrust and drag divided by the weight is greater in the one engine vs two engines operating scenario in the 757 than it is in the A321 at their estimated climb out speeds. This is primarily due to wing geometries.

If you would like to read more then please see the Aircraft Conceptual Design Synthesis from Cranfield university or Aircraft Design:Synthesis and Analysis from Stamford university.

Fred


There is absolutely no specific claim in all that mass of words let alone any Mathematical proof in either statement. What weights? What thrust ratings? Min unstick speeds? 1st stage climb performance? Second stage climb performance? Single engine go around? Max percentage of max gross weight off a given runway and conditions?


Both statements are Extremely vague, broad brush claims at best, and seem to be written to imply knowledge that isn’t there.

I’d also offer that Mexico City to ATL for ex, Delta uses 737-800s and 757-200s out of a high altitude airport situated in a lot of terrain, not an A321 despite having both types on the property.
Last edited by EssentialPowr on Thu Oct 01, 2020 1:29 am, edited 1 time in total.
 
LH707330
Posts: 2498
Joined: Fri Jun 15, 2012 11:27 pm

Re: The Long Range Playbook

Thu Oct 01, 2020 1:07 am

gloom wrote:
kitplane01 wrote:
In a mathematical sense, range is a formula based on fuel fraction, lift/drag ratio, etc.

But I was under the impression that it was easier for planes to get a higher lift/drag ratio at higher speeds in thinner air. That's *why* airliners climb so high. And bigger engines can produce the same thrust at higher altitude in thinner air.


Well, not really. Again, simplified since I don't want the math to kick in too much.

The plane cruises in the air. Let's assume we have an idea to go all the way on constant indicated, where lift to drag is optimum. The higher you go, you keep speed to air at optimum. However, since you go in thinner air, the speed to reference outside will increase, as you need to go faster to maintain dynamic pressure on wings and speedometer. Thta's roughly the difference between IAS and TAS. It's worth 2% (more or less) every 1.000ft. And it's working up until the point where Mach effects kick in (you go constant Mach from that point).

You are not right in pointing out same thrust from engines at higher. The amount of thrust is more or less equal to amount of fuel and air (since they're used to prduce thrust). When going higher, the thrust also reduces, since air flow is also reduced. There used to be Java applet available where different engines were simulated, I remember going over CFM56 rated 23.500lbs sea level. At 737CL max altitude (F370) there was something like 5700 lbs remaining. So, the altitude affects engines quite much.

Since the drag at high is lower, you don't need full thrust. You only need minimal excess to maintain speed (wind change etc) at altitude, while most of takeoff thrust is to accelerate/climb out. Plus, higher-bypass engines seem to have higher thrust at altitude, giving same thrust at lower RPM.

So, to sum up: you get higher true/ground speed at same indicated airspeed when flying higher. The engine will use more or less same thrust and fuel flow to maintain same indicated. You will have enough thrust to maintain speed at altitude, since drag at altitude will be significantly lower, thus offseting lower thrust produced.

Yeah, as simple as it gets. Hope I nailed it.

Cheers,
Adam

PS. For a given frame (and weight, and a little more), you have an optimum IAS speed, where lift to drag is optimum. You would want to be as close to that optimum speed, when going for a range/minimum costs. In most conditions, the plane will go a bit faster, to offset with time spent on route. But the speeds mentioned above will be more-or-less the same for a given type.

This is a great explanation of the phenomena at play without getting too far into the weeds. One thing I think you might have backwards though is this one: "Plus, higher-bypass engines seem to have higher thrust at altitude." Most higher-bypass engines also have larger fans and a lower fan pressure ratio, hence a more severe thrust lapse and less thrust at altitude than a lower-BPR engine of the same thrust. For a given fan RPM though, they should have more thrust, because a bigger fan will push more air, so I think your comment was half right.
 
flipdewaf
Posts: 4168
Joined: Thu Jul 20, 2006 6:28 am

Re: The Long Range Playbook

Thu Oct 01, 2020 5:54 am

EssentialPowr wrote:
flipdewaf wrote:
EssentialPowr wrote:

You had mentioned in This thread before it was deleted that I should review any of your postings if I had questions, so I did as you asked.

An explanation of your comment: (statement 1) “The impact of the safety critical case (what impact??) is more limiting (what limit??) to the 757 than the A321 and personally I’m only flying airlines that calculate takeoff distances based on safety (takeoff distances per Part 121 are based on many variables for each specific takeoff, Requiring all climb limits to be met for the particular conditions!) not fanboys wooping at YouTube videos.”

IS valid, per your request.


oh ok.

(Statement 2) The excess thrust available per unit weight compared to the A321 in normal day to day operations (all engines operating) is is negated more (“negated more?? What??)

Is reduced easier for you to understand?
EssentialPowr wrote:
than it is with the A321 when when calculating using the one engine inoperative case.
i.e. the difference between available thrust and drag divided by the weight is greater in the one engine vs two engines operating scenario in the 757 than it is in the A321 at their estimated climb out speeds. This is primarily due to wing geometries.

If you would like to read more then please see the Aircraft Conceptual Design Synthesis from Cranfield university or Aircraft Design:Synthesis and Analysis from Stamford university.

Fred


There is absolutely no specific claim in all that mass of words let alone any Mathematical proof in either statement. What weights?
There is a very specific claim but you need to brush up on your communication skills to be able to read it.
EssentialPowr wrote:
What thrust ratings?
Min unstick speeds?
1st stage climb performance? Second stage climb performance? Single engine go around? Max percentage of max gross weight off a given runway and conditions?

whilst you are right in that these things all need to be taken in to account when doing the takeoff checks does in no way detract from the fact that climb performance is an important part of that and the geometries of the aircraft (mainly aspect ratio) play a significant part in determining the excess thrust and therefore determining climb rate.

EssentialPowr wrote:


Both statements are Extremely vague, broad brush claims at best, and seem to be written to imply knowledge that isn’t there.

Agree, operation knowledge is not my thing at all. It’s the fundamentals that I do...
EssentialPowr wrote:


I’d also offer that Mexico City to ATL for ex, Delta uses 737-800s and 757-200s out of a high altitude airport situated in a lot of terrain, not an A321 despite having both types on the property.
Sounds reasonable to me, B757 appears to have better hot and high performance, it would be silly not to.

Fred


Sent from my iPhone using Tapatalk
Image
 
EssentialPowr
Posts: 1732
Joined: Wed Sep 06, 2000 10:30 pm

Re: The Long Range Playbook

Thu Oct 01, 2020 3:14 pm

flipdewaf wrote:
EssentialPowr wrote:
flipdewaf wrote:

oh ok.

(Statement 2) The excess thrust available per unit weight compared to the A321 in normal day to day operations (all engines operating) is is negated more (“negated more?? What??)

Is reduced easier for you to understand?
EssentialPowr wrote:
than it is with the A321 when when calculating using the one engine inoperative case.
i.e. the difference between available thrust and drag divided by the weight is greater in the one engine vs two engines operating scenario in the 757 than it is in the A321 at their estimated climb out speeds. This is primarily due to wing geometries.

If you would like to read more then please see the Aircraft Conceptual Design Synthesis from Cranfield university or Aircraft Design:Synthesis and Analysis from Stamford university.

Fred


There is absolutely no specific claim in all that mass of words let alone any Mathematical proof in either statement. What weights?
There is a very specific claim but you need to brush up on your communication skills to be able to read it.
EssentialPowr wrote:
What thrust ratings?
Min unstick speeds?
1st stage climb performance? Second stage climb performance? Single engine go around? Max percentage of max gross weight off a given runway and conditions?

whilst you are right in that these things all need to be taken in to account when doing the takeoff checks does in no way detract from the fact that climb performance is an important part of that and the geometries of the aircraft (mainly aspect ratio) play a significant part in determining the excess thrust and therefore determining climb rate.

EssentialPowr wrote:


Both statements are Extremely vague, broad brush claims at best, and seem to be written to imply knowledge that isn’t there.

Agree, operation knowledge is not my thing at all. It’s the fundamentals that I do...
EssentialPowr wrote:


I’d also offer that Mexico City to ATL for ex, Delta uses 737-800s and 757-200s out of a high altitude airport situated in a lot of terrain, not an A321 despite having both types on the property.
Sounds reasonable to me, B757 appears to have better hot and high performance, it would be silly not to.

Fred


Sent from my iPhone using Tapatalk


Your very vague and unsupported claim is this: “The impact of the safety critical case is more limiting to the 757 than the A321 and personally I’m only flying airlines that calculate takeoff distances based on safety not fanboys wooping at YouTube videos.”

You have used nothing but generalities, no parameters whatsoever, and now completely contradict yourself. If the “B757 appears to have better hot and high performance”, why would airlines that have both types utilize the 757 it if “the safety critical case is more limiting to the 757 than the A321”, because as we have covered, in any Part 121 takeoff an engine failure is ASSUMED??
 
flipdewaf
Posts: 4168
Joined: Thu Jul 20, 2006 6:28 am

Re: The Long Range Playbook

Thu Oct 01, 2020 3:22 pm

EssentialPowr wrote:
flipdewaf wrote:
EssentialPowr wrote:
Is reduced easier for you to understand?


There is absolutely no specific claim in all that mass of words let alone any Mathematical proof in either statement. What weights?
There is a very specific claim but you need to brush up on your communication skills to be able to read it.

whilst you are right in that these things all need to be taken in to account when doing the takeoff checks does in no way detract from the fact that climb performance is an important part of that and the geometries of the aircraft (mainly aspect ratio) play a significant part in determining the excess thrust and therefore determining climb rate.


Agree, operation knowledge is not my thing at all. It’s the fundamentals that I do...
Sounds reasonable to me, B757 appears to have better hot and high performance, it would be silly not to.

Fred


Sent from my iPhone using Tapatalk


Your very vague and unsupported claim is this: “The impact of the safety critical case is more limiting to the 757 than the A321 and personally I’m only flying airlines that calculate takeoff distances based on safety not fanboys wooping at YouTube videos.”

You have used nothing but generalities, no parameters whatsoever, and now completely contradict yourself. If the “B757 appears to have better hot and high performance”, why would airlines that have both types utilize the 757 it if “the safety critical case is more limiting to the 757 than the A321”??

Read it however you want. The performance in the second segment climb phase is more limited by having one engine inop in the 757 than in the A321. The fact that it starts from a higher level (because of a higher level of excess thrust per unit weight at (max operating weights) when all engines are operating

I have at no point contradicted myself. Like you said absolutely correctly you need to put figures on it and when you look at the publicly available data in the ACAPs you can see that there is crossover between the models. I have at no point said that the A321 has better field performance than the 752.

Fred
Image
 
EssentialPowr
Posts: 1732
Joined: Wed Sep 06, 2000 10:30 pm

Re: The Long Range Playbook

Thu Oct 01, 2020 5:57 pm

flipdewaf wrote:
EssentialPowr wrote:
flipdewaf wrote:
Sounds reasonable to me, B757 appears to have better hot and high performance, it would be silly not to.

Fred


Sent from my iPhone using Tapatalk


Your very vague and unsupported claim is this: “The impact of the safety critical case is more limiting to the 757 than the A321 and personally I’m only flying airlines that calculate takeoff distances based on safety not fanboys wooping at YouTube videos.”

You have used nothing but generalities, no parameters whatsoever, and now completely contradict yourself. If the “B757 appears to have better hot and high performance”, why would airlines that have both types utilize the 757 it if “the safety critical case is more limiting to the 757 than the A321”??

Read it however you want. The performance in the second segment climb phase is more limited by having one engine inop in the 757 than in the A321. The fact that it starts from a higher level (because of a higher level of excess thrust per unit weight at (max operating weights) when all engines are operating

I have at no point contradicted myself. Like you said absolutely correctly you need to put figures on it and when you look at the publicly available data in the ACAPs you can see that there is crossover between the models. I have at no point said that the A321 has better field performance than the 752.

Fred


Your claims and quotes:

First claim: “The impact of the safety critical case is more limiting to the 757 than the A321 and personally I’m only flying airlines that calculate takeoff distances based on safety not fanboys wooping at YouTube videos.” (On What Basis do you make that claim? What parameters??)

Second statement: “Sounds reasonable to me, B757 appears to have better hot and high performance, it would be silly not to.“ (Engine loss is assumed!)

Third statement: “I have at no point said that the A321 has better field performance than the 752.“ (You implied the 757 was “more limited” yet make some takeoff safety claim? What?)

Complete contradiction; it doesn’t appear you have a decent concept of performance, specifically takeoff performance, and yet make claims implying expertise that simply isn’t substantiated. You offered for me to review any of your posts, I did, and it was apparent you’re trying to condense others’ thoughts into a meritless claim. This is a technical forum, so be prepared for feedback and maybe double check what you claim...
 
flipdewaf
Posts: 4168
Joined: Thu Jul 20, 2006 6:28 am

The Long Range Playbook

Thu Oct 01, 2020 6:09 pm

EssentialPowr wrote:
flipdewaf wrote:
EssentialPowr wrote:

Your very vague and unsupported claim is this: “The impact of the safety critical case is more limiting to the 757 than the A321 and personally I’m only flying airlines that calculate takeoff distances based on safety not fanboys wooping at YouTube videos.”

You have used nothing but generalities, no parameters whatsoever, and now completely contradict yourself. If the “B757 appears to have better hot and high performance”, why would airlines that have both types utilize the 757 it if “the safety critical case is more limiting to the 757 than the A321”??

Read it however you want. The performance in the second segment climb phase is more limited by having one engine inop in the 757 than in the A321. The fact that it starts from a higher level (because of a higher level of excess thrust per unit weight at (max operating weights) when all engines are operating

I have at no point contradicted myself. Like you said absolutely correctly you need to put figures on it and when you look at the publicly available data in the ACAPs you can see that there is crossover between the models. I have at no point said that the A321 has better field performance than the 752.

Fred


Your claims and quotes:

First claim: “The impact of the safety critical case is more limiting to the 757 than the A321 and personally I’m only flying airlines that calculate takeoff distances based on safety not fanboys wooping at YouTube videos.” (On What Basis do you make that claim? What parameters??)

Second statement: “Sounds reasonable to me, B757 appears to have better hot and high performance, it would be silly not to.“ (Engine loss is assumed!)

Third statement: “I have at no point said that the A321 has better field performance than the 752.“ (You implied the 757 was “more limited” yet make some takeoff safety claim? What?)

Complete contradiction; it doesn’t appear you have a decent concept of performance, specifically takeoff performance, and yet make claims implying expertise that simply isn’t substantiated. You offered for me to review any of your posts, I did, and it was apparent you’re trying to condense others’ thoughts into a meritless claim. This is a technical forum, so be prepared for feedback and maybe double check what you claim...

No, I implied that it was more limiting as the excess trust per unit weight we impacted more for the 757 than for the A321 in the case of engine failure. so the relative performance between the models on the all engines operating scenario is not wholly indicative of that of the engine out. The fact that you wanted to pick an argument about it says more about you than me.

It’s a fair criticism that I could have communicated that better.

Fred


Sent from my iPhone using Tapatalk I
Image
 
EssentialPowr
Posts: 1732
Joined: Wed Sep 06, 2000 10:30 pm

Re: The Long Range Playbook

Thu Oct 01, 2020 7:21 pm

flipdewaf wrote:
EssentialPowr wrote:
flipdewaf wrote:
Read it however you want. The performance in the second segment climb phase is more limited by having one engine inop in the 757 than in the A321. The fact that it starts from a higher level (because of a higher level of excess thrust per unit weight at (max operating weights) when all engines are operating

I have at no point contradicted myself. Like you said absolutely correctly you need to put figures on it and when you look at the publicly available data in the ACAPs you can see that there is crossover between the models. I have at no point said that the A321 has better field performance than the 752.

Fred


Your claims and quotes:

First claim: “The impact of the safety critical case is more limiting to the 757 than the A321 and personally I’m only flying airlines that calculate takeoff distances based on safety not fanboys wooping at YouTube videos.” (On What Basis do you make that claim? What parameters??)

Second statement: “Sounds reasonable to me, B757 appears to have better hot and high performance, it would be silly not to.“ (Engine loss is assumed!)

Third statement: “I have at no point said that the A321 has better field performance than the 752.“ (You implied the 757 was “more limited” yet make some takeoff safety claim? What?)

Complete contradiction; it doesn’t appear you have a decent concept of performance, specifically takeoff performance, and yet make claims implying expertise that simply isn’t substantiated. You offered for me to review any of your posts, I did, and it was apparent you’re trying to condense others’ thoughts into a meritless claim. This is a technical forum, so be prepared for feedback and maybe double check what you claim...



No, I implied that it was more limiting as the excess trust per unit weight we impacted more for the 757 than for the A321 in the case of engine failure. so the relative performance between the models on the all engines operating scenario is not wholly indicative of that of the engine out. The fact that you wanted to pick an argument about it says more about you than me.

It’s a fair criticism that I could have communicated that better.

Fred

Sent from my iPhone using Tapatalk I


Now this is a new, shifted comment that directly contradicts the earlier comment:

“No, I implied that it was more limiting as the excess trust per unit weight we impacted more for the 757 than for the A321 in the case of engine failure. so the relative performance between the models on the all engines operating scenario is not wholly indicative of that of the engine out.“

What the heck does that mean? You’ve talked yourself in to multiple complete contradictions as you’re trying to defend technically meritless comments.

Your other comment, “No, I implied that it was more limiting as the excess trust per unit weight we impacted more for the 757 than for the A321 in the case of engine failure” is, again, a nonsense statement without any parameters defined and since you comment the 757 has better hot and hi performance than the A321 that is a complete contradiction to this statement and the “new” one quoted above!

If you claim expertise while making these types of assertions, a technically competent response would be required but it isn’t possible as there were multiple nonsense comments. I don’t think your knowledge base is very solid as rehashes of others’ comments or presentations is NOT independent technical analysis, and that result clearly shows.
Last edited by EssentialPowr on Thu Oct 01, 2020 7:36 pm, edited 1 time in total.
 
flipdewaf
Posts: 4168
Joined: Thu Jul 20, 2006 6:28 am

Re: The Long Range Playbook

Thu Oct 01, 2020 7:35 pm

EssentialPowr wrote:
flipdewaf wrote:
EssentialPowr wrote:

Your claims and quotes:

First claim: “The impact of the safety critical case is more limiting to the 757 than the A321 and personally I’m only flying airlines that calculate takeoff distances based on safety not fanboys wooping at YouTube videos.” (On What Basis do you make that claim? What parameters??)

Second statement: “Sounds reasonable to me, B757 appears to have better hot and high performance, it would be silly not to.“ (Engine loss is assumed!)

Third statement: “I have at no point said that the A321 has better field performance than the 752.“ (You implied the 757 was “more limited” yet make some takeoff safety claim? What?)

Complete contradiction; it doesn’t appear you have a decent concept of performance, specifically takeoff performance, and yet make claims implying expertise that simply isn’t substantiated. You offered for me to review any of your posts, I did, and it was apparent you’re trying to condense others’ thoughts into a meritless claim. This is a technical forum, so be prepared for feedback and maybe double check what you claim...



No, I implied that it was more limiting as the excess trust per unit weight we impacted more for the 757 than for the A321 in the case of engine failure. so the relative performance between the models on the all engines operating scenario is not wholly indicative of that of the engine out. The fact that you wanted to pick an argument about it says more about you than me.

It’s a fair criticism that I could have communicated that better.

Fred

Sent from my iPhone using Tapatalk I


Now this is a new, shifted comment that directly contradicts the earlier comment:

“No, I implied that it was more limiting as the excess trust per unit weight we impacted more for the 757 than for the A321 in the case of engine failure. so the relative performance between the models on the all engines operating scenario is not wholly indicative of that of the engine out.“

What the heck does that mean? You’ve talked yourself in to multiple complete contradictions as you’re trying to defend technically meritless comments.
Your other comment, “No, I implied that it was more limiting as the excess trust per unit weight we impacted more for the 757 than for the A321 in the case of engine failure” is, again, a nonsense statement without any parameters defined and since you comment the 757 has better hot and hi performance than the A321 that is a complete contradiction (again, based on nonsense in any case).

If you claim expertise while making these types of assertions, a technically competent response would be required but it isn’t possible as there were multiple nonsense comments. I don’t think your knowledge base is very solid as rehashes of others’ comments or presentations is NOT independent technical analysis, and that result clearly shows.

If you don’t understand I can take it to a level you may understand. What is you technical knowledge level?

Fred


Sent from my iPhone using Tapatalk
Image
 
EssentialPowr
Posts: 1732
Joined: Wed Sep 06, 2000 10:30 pm

Re: The Long Range Playbook

Thu Oct 01, 2020 7:38 pm

flipdewaf wrote:
If you don’t understand I can take it to a level you may understand. What is you technical knowledge level?

Fred


Sent from my iPhone using Tapatalk


Yes, please do.

Explain it as technically and concisely as possible:

“The impact of the safety critical case is more limiting to the 757 than the A321 and personally I’m only flying airlines that calculate takeoff distances based on safety”

in Conjunction with:

“No, I implied that it was more limiting as the excess trust per unit weight we impacted more for the 757 than for the A321 in the case of engine failure. so the relative performance between the models on the all engines operating scenario is not wholly indicative of that of the engine out.“

And:

“Sounds reasonable to me, B757 appears to have better hot and high performance, it would be silly not to.“

What is your proof of ANY of these, let alone the fact they contradict each other...
Last edited by EssentialPowr on Thu Oct 01, 2020 7:43 pm, edited 1 time in total.
 
flipdewaf
Posts: 4168
Joined: Thu Jul 20, 2006 6:28 am

Re: The Long Range Playbook

Thu Oct 01, 2020 7:42 pm

EssentialPowr wrote:
flipdewaf wrote:
If you don’t understand I can take it to a level you may understand. What is you technical knowledge level?

Fred


Sent from my iPhone using Tapatalk


Yes, please do.

Explain it as technically and concisely as possible:

“The impact of the safety critical case is more limiting to the 757 than the A321 and personally I’m only flying airlines that calculate takeoff distances based on safety”

in Conjunction with:

“No, I implied that it was more limiting as the excess trust per unit weight we impacted more for the 757 than for the A321 in the case of engine failure. so the relative performance between the models on the all engines operating scenario is not wholly indicative of that of the engine out.“

I asked what level you need not how concise...


Sent from my iPhone using Tapatalk
Image
 
EssentialPowr
Posts: 1732
Joined: Wed Sep 06, 2000 10:30 pm

Re: The Long Range Playbook

Thu Oct 01, 2020 7:44 pm

Flip

Again,
“ Yes, please do. Explain it as technically and concisely as possible”

My qualifications and experience aren’t the issue. These are your claims, so please demystify this... had you that level of competence about which you ask, your claims probably wouldn’t have been made in the first place, and now the pause to try to find some way to defend the them? Ok.
 
User avatar
lightsaber
Moderator
Posts: 22676
Joined: Wed Jan 19, 2005 10:55 pm

Re: The Long Range Playbook

Fri Oct 02, 2020 5:00 am

Thread deteriorated to personal attacks.
10 months without TV. The best decision of my life.

Who is online

Users browsing this forum: No registered users and 22 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