morrisond wrote:Actually the ACAP agrees with WIKI - if you go to 3-62 in the Boeing ACAP it shows 8,500' at ISA standard and 0 Elevation as well.
Originally I as looking at the wrong table as well (I went to the last one 3-65) and thinking 10,250' was optimistic.
Good catch, but I think we need to be specific here. There is no "wrong table" as such, only 2 different ones.
There is a table for the 25k lb thrust LEAP which shows the 737-9 take off at 0ft altitude as 10,250ft
There is ALSO a table for a high thrust variant with a 28k lb thrust LEAP which shows the 737-9 take off at 0ft altitude as 8,500ft
So we have a comparison.
Base 737-9 at 88t and 25k lb thrust at 0 ft altitude is 10,250ft
Base A321NEO at 93.5t and 33k lb thrust at 0 ft altitude is 7,250ft
High thrust 737-9 at 88t and 28k lb thrust at 0 ft altitude is 8,500ft
This of course compares the basic 737-9 with the highest thrust to an A321XLR which is 2 weight growth increments up on the basic NEO with the lowest thrust (33k lb)
The A321NEO is also available with 35k lb thrust if required - a 6% increase.
If the 737-9 12% thrust increase delivers 1,750ft better field performance, I'd expect the 321NEO's 6% increase to deliver something like 750ft, giving
High Thrust A321NEO at 93.5t and 35k lb thrust at 0 ft altitude being 6,500ft
Flightglobal state that the design intent for the high lift system is that V1 stays the same for the XLR as it is for the standard NEO
https://www.flightglobal.com/analysis/a ... 41.article
He adds that the intention with the switch to the single-slotted inboard flaps on the A321XLR is to reduce weight and complexity without exceeding the V-speeds of the original A321.
As V is constant, acceleration will be inversely proportional to mass.
The mass increase from 93.5t to 101t is 8%
Acceleration will be down 8%, and time will be up 8%
distance will be proportional to acceleration x time^2
i.e 0.92 x 1.08^2.
The increase in take-off distance will be 7%
Which means that
Base A321XLR at 101t and 33k lb thrust at 0 ft altitude is going to be (7,250ft x 1.07) = 7 750 ft
High thrust A321XLR at 101t and 35k lb thrust at 0 ft altitude is going to be (6,500ft x 1.07) = 7 000 ft
Considerably less than the 737-9 MAX, and squarely in 757-200 field performance territory
757-200 figures from here
https://www.boeing.com/resources/boeing ... 757_23.pdf
Base 757-200 at 116t and 37k lb RR 535E4 at 0ft altitude being 7,250ft
Base 757-200 at 116t and 37k lb PW 2037 at 0ft altitude being 9,500ft
High thrust 757-200 at 116t and 40k lb RR 535E4B at 0ft altitude being 6,500ft
High thrust 757-200 at 116t and 40k lb PW 2040 at 0ft altitude being 7,500ft
If the XLR calculation above is valid, that will put the XLR field performance somewhere between the RR powered 757-200 and the P+W powered 757-200.
The XLR of course flies a LOT further and therefore is disadvantaged in this comparison