Hi all,
not sure if this has been discussed before, but on a recent departure with the A220-100, I noticed that I haven't experienced such a high thrust takeoff ( i.e. being pushed back in your seat) since the B757-200. So my question is; is the A220-100/CS100 the new 757-200 in. terms of takeoff performance?

( I am aware of the significant differences in weight and use of aircraft)

Thanks

It is pretty powerful indeed, mostly due to the fact that the same engines are being used on the bigger A220-300. If it has to be powerful enough for the big one, it's therefor overpowered for the smaller one.

They were able to develop a 757-300 because the engines for the 757-200 were powerful enough to power a larger aircraft.

By the way, the 717 is pretty powerful as well. It also pushes you back in your seat on take-off, for which it needs remarkably little distance.

It has been discussed in the past. If I recall correct, the A330-200 is more powerful than the 757-200, so the new 757-200 has been around for over 20 years already.

VSMUT wrote:

It has been discussed in the past. If I recall correct, the A330-200 is more powerful than the 757-200, so the new 757-200 has been around for over 20 years already.

I thought the OP is talking about A220 rather than A330?

chonetsao wrote:

VSMUT wrote:

It has been discussed in the past. If I recall correct, the A330-200 is more powerful than the 757-200, so the new 757-200 has been around for over 20 years already.

I thought the OP is talking about A220 rather than A330?

I know that, but OP is asking about an aircraft with as great power-to-weight ratio as the 757. I'm pointing out that the A330-200 had a greater power-to-weight ratio long before the A220 did.

I am VERY doubtful about this, but this article says that the 757 has the second-highest thrust 2 weight ratio of any pax airliner, behind concorde.
https://www.flyingmag.com/story/aircraf ... n-classic/

Has the A332 or 220 or any airliner have beaten the 757 by now, and is this statement even true? I personally don't think it is..

I always assumed the noticeable take-off push in the 757 was as it had a good power to weight ratio, but was probably old enough not to have an electronic launch control which reduced thrust unless at MTOW. A newer plane might have a similar or even higher power to weight ratio, but would never use full thrust unless loaded which would dampen the perceived acceleration anyway.

Turnhouse1 wrote:

I always assumed the noticeable take-off push in the 757 was as it had a good power to weight ratio, but was probably old enough not to have an electronic launch control which reduced thrust unless at MTOW. A newer plane might have a similar or even higher power to weight ratio, but would never use full thrust unless loaded which would dampen the perceived acceleration anyway.

We don’t have “launch control” on planes, we have performance engineering.

Turnhouse1 wrote:

I always assumed the noticeable take-off push in the 757 was as it had a good power to weight ratio, but was probably old enough not to have an electronic launch control which reduced thrust unless at MTOW. A newer plane might have a similar or even higher power to weight ratio, but would never use full thrust unless loaded which would dampen the perceived acceleration anyway.

Reduced thrust for take-off was a thing long before the 757, and it was part of normal operations on the 757, as it is with pretty much any jet transport since the 70s (60s?).

Reducing thrust isn't done electronically and we don't have launch control. Takeoff thrust is simply set to the calculated value from the performance calculation, either manually or more commonly with autothrust/autothrottle.

Dear Swiss03,

Question : was your takeoff performed on a contaminated runway? Was this a short flight, e.g. Zurich-Geneva? Was the cabin rather empty?

If yes, you were lucky to experience a full power takeoff in a light plane.

hitower3 wrote:

Dear Swiss03,

Question : was your takeoff performed on a contaminated runway? Was this a short flight, e.g. Zurich-Geneva? Was the cabin rather empty?

If yes, you were lucky to experience a full power takeoff in a light plane.

On a contaminated runway, it could well have been a fixed derate.

Starlionblue wrote:

On a contaminated runway, it could well have been a fixed derate.

Dear Starlionblue,

Oh, ok - I thought that contaminated runways (e.g. snow) would often mandate a full power takeoff as per SOP, because the start-stop distance is longer.
I stand corrected then.

Best regards,
Hendric

PatrickZ80 wrote:

It is pretty powerful indeed, mostly due to the fact that the same engines are being used on the bigger A220-300. If it has to be powerful enough for the big one, it's therefor overpowered for the smaller one.

They were able to develop a 757-300 because the engines for the 757-200 were powerful enough to power a larger aircraft.

By the way, the 717 is pretty powerful as well. It also pushes you back in your seat on take-off, for which it needs remarkably little distance.

The even more important thing with the 757 is the wing.

hitower3 wrote:

Starlionblue wrote:

On a contaminated runway, it could well have been a fixed derate.

Dear Starlionblue,

Oh, ok - I thought that contaminated runways (e.g. snow) would often mandate a full power takeoff as per SOP, because the start-stop distance is longer.
I stand corrected then.

Best regards,
Hendric

Fixed derate is full power at a lower, different rated power. Vmcg considerations dictating the derate.

VSMUT wrote:

It has been discussed in the past. If I recall correct, the A330-200 is more powerful than the 757-200, so the new 757-200 has been around for over 20 years already.

The A332 and A333 have the same MTOW of 242t, same wing and the same engine thrust.

The A321-NEO has a (very slightly) higher T/W than the 752.

hitower3 wrote:

Starlionblue wrote:

On a contaminated runway, it could well have been a fixed derate.

Dear Starlionblue,

Oh, ok - I thought that contaminated runways (e.g. snow) would often mandate a full power takeoff as per SOP, because the start-stop distance is longer.
I stand corrected then.

Best regards,
Hendric

As GalaxyFlyer says, a fixed derate is full power, with full power being "re-defined" at a lower rating than actual full power.


The explanation for why you might derate on a contaminated runway is a bit complex, but bear with me.

On a contaminated runway, Vmcg (minimum control speed in case of an engine failure on the ground) increases because of reduced surface friction. If you lose an engine below Vmcg, you may run out of yaw control authority.

V1 must always be higher than Vmcg. This leads to a problem, as a high V1 reduces the available stopping distance, which in turn can restrict your payload. On a short and/or contaminated runway, the accelerate-stop distance is typically constraining.

How to lower V1, then? By lowering Vmcg. This is done by decreasing the thrust, which decreases the yaw moment from an engine failure. Enter a fixed derate, e.g. 20%.

With our new, lower V1, the available stopping distance is increased.

This leads to the somewhat counterintuitive situation where a lower takeoff thrust setting can allow you to take more payload off the same runway.


Note: A fixed derate is not the same as assumed temperature thrust. One important difference is that if you have an engine failure with a fixed derate, you may not go to TOGA until above a certain speed.

still do not understand how change Vmin-control can change V1, which in any case controllable.

Armadillo1 wrote:

still do not understand how change Vmin-control can change V1, which in any case controllable.

Because the lowest V1 must be greater or equal that Vmc.

So suppose you are able to get a lower V1, you still have to make it artificially higher to satisfy Vmca requirements.
If you can bring down Vcma by derating the engines, you can then bring down V1.

Starlionblue wrote:

The explanation for why you might derate on a contaminated runway is a bit complex, but bear with me.

Dear Starlionblue,

Thank you very much for your extensive and insightful answer.
I might need to read it a few more times to fully understand it, though...

Best regards,
Hendric

SAAFNAV wrote:

Armadillo1 wrote:

still do not understand how change Vmin-control can change V1, which in any case controllable.

Because the lowest V1 must be greater or equal that Vmc.

So suppose you are able to get a lower V1, you still have to make it artificially higher to satisfy Vmca requirements.
If you can bring down Vcma by derating the engines, you can then bring down V1.

To quote the excellent "Understanding Takeoff Speeds" paper by Airbus (linked below):

"If an engine failure is detected after V1, the takeoff must be continued. This implies that the aircraft must be controllable on ground. Therefore, V1 is always greater than VMCG."

Vmcg is predicated on one engine at takeoff thrust and one failed. So what happens with an engine failure below Vmcg? You'd immediately set the thrust to idle, thus removing the offending yaw moment. Since the only option with an engine failure below Vmcg is to reject the takeoff, Vmcg must be lower than V1.

The paper includes a section on the relationship between V1, derate, and Vmcg.

Source: https://www.skybrary.aero/bookshelf/books/493.pdf

hitower3 wrote:

Starlionblue wrote:

The explanation for why you might derate on a contaminated runway is a bit complex, but bear with me.

Dear Starlionblue,

Thank you very much for your extensive and insightful answer.
I might need to read it a few more times to fully understand it, though...

Best regards,
Hendric

I had to work through it quite a few times in ground school performance theory before it clicked.

IIRC, V1min is defined as Vmcg x 1.05Vmcg

IIRC the CRJ-700's T/W is up there near, if not slightly higher than the 752. I had the opportunity to fly on a CRJ7 and connect to an A332, so I got to compare both on the same day. The -700, especially from a 6500-foot runway was a little rocket and had me pushed into the seat. While the A332 is powerful, it didn't have the same seat-pressing effect as the CRJ.

N965UW wrote:

IIRC the CRJ-700's T/W is up there near, if not slightly higher than the 752. I had the opportunity to fly on a CRJ7 and connect to an A332, so I got to compare both on the same day. The -700, especially from a 6500-foot runway was a little rocket and had me pushed into the seat. While the A332 is powerful, it didn't have the same seat-pressing effect as the CRJ.

Also remember the 332 is a lot more likely to be loaded up with passengers and cargo. It will not exactly jump off the ground on a 9 to 10 hour flight. I was on a CR7 that rolled about 2100 feet on a 30 minute flight with six passengers, Plus it was maximum available thrust due to a contaminated field with the restrictions that Starlionblue had mentioned

DylanHarvey wrote:

N965UW wrote:

IIRC the CRJ-700's T/W is up there near, if not slightly higher than the 752. I had the opportunity to fly on a CRJ7 and connect to an A332, so I got to compare both on the same day. The -700, especially from a 6500-foot runway was a little rocket and had me pushed into the seat. While the A332 is powerful, it didn't have the same seat-pressing effect as the CRJ.

Also remember the 332 is a lot more likely to be loaded up with passengers and cargo. It will not exactly jump off the ground on a 9 to 10 hour flight. I was on a CR7 that rolled about 2100 feet on a 30 minute flight with six passengers, Plus it was maximum available thrust due to a contaminated field with the restrictions that Starlionblue had mentioned

That is true. The A332 flight I described was a 7.5/8hr hop and had a good amount of passengers. I'm not sure how much cargo AA carries on seasonal routes between CLT and Europe, but we were light enough for a FL370 initial cruise (380 on the return).

The CRJ flight was nearly full on a 1hr20min trip, no runway contamination and still had impressive performance. The return was probably about 3/4 full and I know it was a reduced thrust takeoff since climb thrust was set higher after rotation.

Passengers can’t make a valid comparison on performance, way too many variables that are not known. Sound isn’t a valid way to measure thrust levels.

N965UW wrote:

DylanHarvey wrote:

N965UW wrote:

IIRC the CRJ-700's T/W is up there near, if not slightly higher than the 752. I had the opportunity to fly on a CRJ7 and connect to an A332, so I got to compare both on the same day. The -700, especially from a 6500-foot runway was a little rocket and had me pushed into the seat. While the A332 is powerful, it didn't have the same seat-pressing effect as the CRJ.

Also remember the 332 is a lot more likely to be loaded up with passengers and cargo. It will not exactly jump off the ground on a 9 to 10 hour flight. I was on a CR7 that rolled about 2100 feet on a 30 minute flight with six passengers, Plus it was maximum available thrust due to a contaminated field with the restrictions that Starlionblue had mentioned

That is true. The A332 flight I described was a 7.5/8hr hop and had a good amount of passengers. I'm not sure how much cargo AA carries on seasonal routes between CLT and Europe, but we were light enough for a FL370 initial cruise (380 on the return).

The CRJ flight was nearly full on a 1hr20min trip, no runway contamination and still had impressive performance. The return was probably about 3/4 full and I know it was a reduced thrust takeoff since climb thrust was set higher after rotation.

As mentioned, you can't get a valid comparison from the cabin. For starters, almost all take-offs use reduced thrust.

Any airliner, especially a twin, has gobs of excess thrust, but you never really use it. On a ferry flight with no payload, you'd typically use reduced thrust.

The only time I really felt that ultimate power was during base training. A330 with no pax or cargo. Only about 20 tonnes of fuel. Touch and goes with TOGA. Talk about rocketship. You were at 800 feet and reducing thrust before you could blink.

But again, that kind of performance is available in any airliner.

Starlionblue wrote:

N965UW wrote:

DylanHarvey wrote:

Also remember the 332 is a lot more likely to be loaded up with passengers and cargo. It will not exactly jump off the ground on a 9 to 10 hour flight. I was on a CR7 that rolled about 2100 feet on a 30 minute flight with six passengers, Plus it was maximum available thrust due to a contaminated field with the restrictions that Starlionblue had mentioned

That is true. The A332 flight I described was a 7.5/8hr hop and had a good amount of passengers. I'm not sure how much cargo AA carries on seasonal routes between CLT and Europe, but we were light enough for a FL370 initial cruise (380 on the return).

The CRJ flight was nearly full on a 1hr20min trip, no runway contamination and still had impressive performance. The return was probably about 3/4 full and I know it was a reduced thrust takeoff since climb thrust was set higher after rotation.

As mentioned, you can't get a valid comparison from the cabin. For starters, almost all take-offs use reduced thrust.

Any airliner, especially a twin, has gobs of excess thrust, but you never really use it. On a ferry flight with no payload, you'd typically use reduced thrust.

The only time I really felt that ultimate power was during base training. A330 with no pax or cargo. Only about 20 tonnes of fuel. Touch and goes with TOGA. Talk about rocketship. You were at 800 feet and reducing thrust before you could blink.

But again, that kind of performance is available in any airliner.

You can make pretty much any aircraft a rocket ship. If you firewall a 77W you’d think you were going to get some impressive performance. Why use 3000 feet of a 15,000 runway when you have no performance limitations and you can derate comfortably

DylanHarvey wrote:

Starlionblue wrote:

N965UW wrote:

That is true. The A332 flight I described was a 7.5/8hr hop and had a good amount of passengers. I'm not sure how much cargo AA carries on seasonal routes between CLT and Europe, but we were light enough for a FL370 initial cruise (380 on the return).

The CRJ flight was nearly full on a 1hr20min trip, no runway contamination and still had impressive performance. The return was probably about 3/4 full and I know it was a reduced thrust takeoff since climb thrust was set higher after rotation.

As mentioned, you can't get a valid comparison from the cabin. For starters, almost all take-offs use reduced thrust.

Any airliner, especially a twin, has gobs of excess thrust, but you never really use it. On a ferry flight with no payload, you'd typically use reduced thrust.

The only time I really felt that ultimate power was during base training. A330 with no pax or cargo. Only about 20 tonnes of fuel. Touch and goes with TOGA. Talk about rocketship. You were at 800 feet and reducing thrust before you could blink.

But again, that kind of performance is available in any airliner.

You can make pretty much any aircraft a rocket ship. If you firewall a 77W you’d think you were going to get some impressive performance. Why use 3000 feet of a 15,000 runway when you have no performance limitations and you can derate comfortably

Rocketships indeed. Here's the A380 showing off. https://youtu.be/DaueROcGyeA

I remember being a passenger departing from KATL on a NW 75 back in the day. However they crunched their speeds up front: I was in a state of surprise, and inadvertently blurted "Holy @$#@!" out loud as it seemed that from spool to Vr... felt like mere seconds, jumping off a long, dry runway. She got homesick to the angels faster than the Lancair I had flown a week prior. Perhaps I was lucky enough to experience the requisite full-power T/O?

T/W ratios are one thing. The wing on the 75? I can't imagine any other airliner (even lightly loaded at TOGA) doing this:

https://youtu.be/ddusBoFNr-s?t=19

rjsampson wrote:

I remember being a passenger departing from KATL on a NW 75 back in the day. However they crunched their speeds up front: I was in a state of surprise, and inadvertently blurted "Holy @$#@!" out loud as it seemed that from spool to Vr... felt like mere seconds, jumping off a long, dry runway. She got homesick to the angels faster than the Lancair I had flown a week prior. Perhaps I was lucky enough to experience the requisite full-power T/O?

T/W ratios are one thing. The wing on the 75? I can't imagine any other airliner (even lightly loaded at TOGA) doing this:

https://youtu.be/ddusBoFNr-s?t=19

Indeed short. But again, any airliner can be a rocketship.

747. https://youtu.be/bl-vigh_Afg
767. https://youtu.be/FnklcClSgts

I don’t if it’s still true, but there was a requirement to do a rated power take-off on some schedule to ensure it was available. I’ve done them on light airplanes only because it was scheduled.

Smokiest 767 I’ve ever seen !

GalaxyFlyer wrote:

I don’t if it’s still true, but there was a requirement to do a rated power take-off on some schedule to ensure it was available. I’ve done them on light airplanes only because it was scheduled.

Yes, that is still true. At the airline at which I work, there will periodically be an annotation on our flight paperwork, "Accomplish full thrust takeoff."

I do not know what the interval is; dictated by Maintenance Control.

This requirement does not take into account stage length or load so if the aircraft is lightweight and environmental conditions are favorable, yes, you will experience impressive takeoff and climb performance.

e38

Twin engine aircraft have so much excess thrust. Derates can you be in order of 20+ percent in a lot of instances. You do not need to come close to firewall and a 77W at MTOW.

I had the chance to work on the A221, once, and I was very interested in what it’s characteristics would be like. I don’t recall it accelerating forcefully, but did so quickly (short flight) and initial climb did ‘feel’ steep... wether it really way, I don’t know. Sound wise, once at cruise, I couldn’t tell if it was much quieter than the A31 I just got off... again, sound is a perception and is related to different characteristics of a specific flight, such as altitude.

As a FA, I’ve noticed certain performance characteristics from specific fleet types, so I find this subject rather interesting. For example, it’s not uncommon to have a very long takeoff roll on the 737-900ER (imagine that) when using a long runway at a major airport. Same can be said for the 757-300 on a mid-con flight from LAS or a Hawaiian islands flight from LAX. There are just so many variables at play. Personally, The MD90 always felt typically aggressive to me on takeoff because the rotation characteristics- a pronounced nose up and perception of a steep initial climb- that may or may not be the case, and from my limited technical knowledge, I’d wager its not ‘actually’ “out climbing” another modern twin, necessarily. And, for what it’s worth, my own anecdotal experience after spending so many hours on these different airplanes, in different parts of the cabin and in different conditions, is the A319 imparts the most often highest sense of physical force when the engines are set to takeoff power over most conditions. Again, this could be actually true or simply due to the number of circumstances that influence our perception of “power.”

I couldn’t tell you how many hundreds of 757 flights I’ve worked in the last five years alone- there are different perceptions wether you are seated in the front, mid, or back. The only thing perception wise I can attest is the rotation and initial climb. This may be due to aerodynamics of the aircraft, especially at certain weights: a momentary feeling of a strong weightless pull upward, which I’ve always imagined is, at least in part, due to the wing. That said, when I think of the 757 I actually think of how lovely she taxis versus the the 320 and 737 variants, such a nice ride to and from the runway, makes me sleepy just writing about it.

The most powerful takeoffs I’ve ever experienced, again from my individual personal perception, have been the A332, and to a lesser extent A333, as seated in the very back. These are trans Atlantic flights- the power perception comes from the exhaust flow blast against the fuselage and a subsequent and noticeable forceful vibration of cabin equipment, especially the shaking of ceiling panels and overhead bins. Of course, these perceptions are just that and could be due to a number of things other than actual real ‘power’ such as the engineering & construction of the cabin interior modules...etc.

Looking forward to working more A220 flights and “feeling” the characteristics of that plane. I would love to sit in the back, behind the wings, to compare engine exhaust sound versus, say, the A319...which is pretty loud!

Experienced something similar a few years back on a KLM 777-300 between DPS - SIN. Flight was full, but the take-off thrust did feel pretty solid & way more than a regular 777 take off roll. Not sure if there were any Runway limitations being enforced that day, but it certainly did feel like he was going all out that evening.

quarryking wrote:

Experienced something similar a few years back on a KLM 777-300 between DPS - SIN. Flight was full, but the take-off thrust did feel pretty solid & way more than a regular 777 take off roll. Not sure if there were any Runway limitations being enforced that day, but it certainly did feel like he was going all out that evening.

You could have been runway limited, which would have pushed up the thrust level. The runway at DPS is "only" 3000m, which is a bit on the short side for that kind of operation.

DylanHarvey wrote:

Twin engine aircraft have so much excess thrust. Derates can you be in order of 20+ percent in a lot of instances. You do not need to come close to firewall and a 77W at MTOW.

In fact, launching a lightly loaded 77W at TOGA (due MEL / windshear mitigation / bit of fun) into a busy airspace with a low initial level-off is a sure-fire way of ending up having a little pleasantry-free chat with the CP if you don't know what you're doing and haven't briefed the crap out of it...
Proper threat.


To repeat what's been said several times, a passenger will rarely feel the true thrust/weight ratio on an airliner, especially on widebodies which use deeper derates more often.

It bears repeating, but a heavy B739 at full thrust will accelerate and climb more strongly, in some cases, than a lightly loaded 752 on a derated takeoff. Not a pilot, but I think this statement is correct.

LCDFlight wrote:

It bears repeating, but a heavy B739 at full thrust will accelerate and climb more strongly, in some cases, than a lightly loaded 752 on a derated takeoff. Not a pilot, but I think this statement is correct.

Maybe

GalaxyFlyer wrote:

LCDFlight wrote:

It bears repeating, but a heavy B739 at full thrust will accelerate and climb more strongly, in some cases, than a lightly loaded 752 on a derated takeoff. Not a pilot, but I think this statement is correct.

Maybe

Well I would think "definitely," as the same could be said when comparing TO performance of any two aircraft: Comparing the first at full thrust, to the second at derated thrust. (How must thrust will be derated on the second aircraft?)

How “lightly” is lightly? How much of a derate applied? Is “full” thrust full or at reduced setting or full at the derate? Remember “full” means at the rating, so you can have “full” derate 1 or wash out the derates. Is the 757 so light, the TO is based on reduced thrust on the derate power. And nobody in the back will know any of this.

GalaxyFlyer wrote:

How “lightly” is lightly? How much of a derate applied? Is “full” thrust full or at reduced setting or full at the derate? Remember “full” means at the rating, so you can have “full” derate 1 or wash out the derates. Is the 757 so light, the TO is based on reduced thrust on the derate power. And nobody in the back will know any of this.

Exactly.

744SPX wrote:

The Learjet 31 (and earlier 23) takes the cake for civilian aircraft, and that includes the Concorde.

Apparently, flying those early Learjets wasn't worth the T/W ratio. There's a user on this forum, tb727. His color commentary is quite... interesting (as are the hundred+ posts that followed)

viewtopic.php?t=774999

Buckle up. Apparently, those were terrible airplanes.

GalaxyFlyer wrote:

How “lightly” is lightly? How much of a derate applied? Is “full” thrust full or at reduced setting or full at the derate? Remember “full” means at the rating, so you can have “full” derate 1 or wash out the derates. Is the 757 so light, the TO is based on reduced thrust on the derate power. And nobody in the back will know any of this.

Yes I was just driving for the same point you made, which is passengers can't feel the "aircraft performance" from the passenger cabin. Because it's not very common that pilots are using the max performance. And it's even less common that passengers sit in two different types, both doing max performance, and can accurately compare.

Humans are not very good at inertial guidance anyhow. But yes, if you are in a 752 or A220-100 doing max performance in a light plane, it's going to be spectacular.