Discussion about the B757 replacement

Scott  Hamilton from Leeham has a post about the possible replacement of the B757.
 King5 then came out with it's own story, citing Scott.

I have to say I do not believe we will see a clean-sheet aircraft as a replacement for the B757 - at least not in the time frame Scott is mentioning. He sees a window for EIS opening in 2025, with Boeing probably being the first mover.
The reasons:
  1. Business Case for B737MAX and A320neo. The A320neo will delivered from October 2015 onwards, the B737MAX roughly two years later (July 2017 as it looks right now). If a B757 replacement would be available in 2025, announced to the public by 2020, the B737MAX-9 would be dead by then. The B757 replacement aircraft (B757R) would be more economical on all missions - not just on the longer ones. In other words: if the -MAX9 would be more economical on shorter missions, there would be no justification for launching the B757R. In the end this is the reason why we are waiting for the the re-engined versions of the narrowbodies today instead of clean-sheet aircraft: it was not possible to develop an aircraft with 20% lower cash operating cost with an tube-and-wing aircraft. A revolutionary concept, say a blended wing body with open rotors was conceived as a risk that was too high (additionally it is questionable how you want to seat the passengers in  such an aircraft, how you want to handle boarding and de-boarding, how airport layouts would have to change etc., etc.). Now, with the re-engined aircraft, the hurdle to achieve a significant improvement is even higher. But if Boeing (or Airbus - or anyone else) would be able to do so, there would be no need for the largest versions of today's narrowbody lines anymore. The A321 and the B737MAX-9 would be dead immediately for a relatively small portion of the narrowbody market (or would the B757R be a small widebody?).
  2. The engine OEM's and their Business Case(s): a B757R would need more thrust than the A321 and the B737MAX-9, even if it would be a complete carbon fibre airliner. So the PW1100G and the LEAP-1A would not fit. They could get a thrust increase, of course, but by how much. The engine competition between CFM, PW and RR, at least for the A320neo, was fierce and every fraction of SFC counted, so we can assume that the engine maker came up with the smallest possible engine core, driving up core temperatures and bypass ratio and thus thermal and propulsive efficiency, implying the most advanced cooling technology and materials . To increase thrust, even more sophisticated cooling and materials are needed. maybe CFM can borrow some more of these from the GE9X in a few years. That would enable more thrust with the same efficiency or a better SFC (through less cooling air usage) at the same thrust, showing the way for a PIP package for the LEAP-1A/B/C (and of course we can expect that PW is also looking at advanced cooling and materials). But it would not enhance thrust capabilities and SFC at the same time. To do that both engine makers (or RR of course) would have to invest in a complete new engine with a new core and possibly a complete new cycle philosophy. This would mean to take another $1 billion, after investing a lot of money in the engine line-up we currently see in development. The Business Case, for which the amount of spare parts sold is so critical, would never turn from red to black for the current LEAP and PW1000G engines, as they would depreciate in value and would be replaced too early and too fast.
I would rather see the possibility that the current largest models (-MAX9 and A321) would get
  • another stretch (adding a -MAX10 and a A322)
  • a new, larger wing for the then two largest members of the family
  • maybe using AlLi for the fuselage to save weight
  • an engine thrust increase as described above
With that, for the aircraft and engine makers the Business Case is somewhat protected, as the invest is approximately halved.

Of course, 2025 is a long time to ago and there could happen a lot - so let's wait for 2020 and see what aircraft will be announced...


  1. That is a very interesting point AeroT. As it's mostly the case, just about every airline is asking for more range, but when the aircraft gets heavy because of the major beefing up that must be accounted for on the design, some of these airlines start complaining that it was done to satisfy certain airline or carrier and not for economics of the aircraft. In the end, however, they choose range over economics (a la Lufthansa choice of not going for the 787-10 even though it was exactly what they argued for before placing an order for a different plane with a lot more range but supposedly less economical on route up to 6000nm).
    So, the big question is: How many airline would order a 757 replacement with plenty of range but equal economy to an A321NEO or B737-9Max on medium range route (3000nm or less) if the latter planes are so much cheaper to buy?

  2. Thanks, AeroTurbo : engine OEMs' business case adds to airframer logic : the 757 niche will dilute upwards (but only marginally so) into additional demand for A330/A350 vs 787, whereas downwards (to a vast majority) this niche will spur additional demand for A321 (!) vs 739 (?) and/or ER versions/stretches thereof. Btw, a special Business Case emerges for H22QR. The niche remnants (??) would hardly justify any 757R as such.

  3. It not about the 757. It is about 200-250 seats on flights up to 4500NM. Currently flown by 757, 762, A300, TU154, A310 and A330/787s because of unavailability of a suitable aircraft. EMEA, TransCon, Intra Asia and Leisure seem the biggest markets.

    Btwm the PW1100G is dimensioned to deliver up to 40.000 lbs, 20% more then the A321 maximum installed thrust. http://www.flightglobal.com/news/articles/gtf-able-to-power-twin-aisle-narrowbody-pratt-whitney-338925/

    1. With H22QR's 13 belly-position for AKH, eg three of which may be replaced with ACT, pluss with Bob Saïa's GTF @ 40+ klbs (Thank you, Mary !) we'd have near three extra flight hours worth of range ... isn't that bringing us close enough to where you want to take us, Keesje ?

    2. keesje, please take Saja's commments about the GTf delivering up to 40klbf thrust as a general comment about the GTF, not the PW1100G. This engine will definitely not be able to deliver 40klbf. The core was sized to get the best possible SFC for the thrust needed for the A320neo.

  4. Consider that Pratt claims it has a roadmap to increase the GTF fuel savings to 20-30% from 15% by the middle of the next decade, and lets assume that the LEAP guys will have a bag of ideas. Both Boeing and Airbus will continue to tweak a little here and there for maybe another 5% on their planes. This will narrow the gap to the 757 further, so the niche that you really need an 757 replacement for will get even smaller as a by-product. So whatever plane if ever fills this niche will probably also do this more as a by product than as a deliberate development.

    1. If the current gap can be "filled" by incremental engine and aircraft advancements, then one day the A321neo and maybe also the B737-9MAX can fill the B757 niche. But the market is not large enough to make a business case for a standalone B757R product. If there ever will be a true B757R, then it must be a part of the A320/B737 successor families.

    2. Agreed ! The TECHNICAL side of the picture is crystalline : it's going to be (a) derivative design(s) of existing aircraft families. COMMERCIALLY, is the primary requirement first to offer a P2P 3,500 up to 4,500 nm range capability @ 200+ pax ? or is it to do away with the infamed "757 syndrome" (a string of in-flight service plus ground turn-around inefficiencies) ?

    3. Btw, if the motto "it takes a 757 to replace a 757" is relettered slightly, why not call in all those nice and fine aircraft to undergo a facelift to H5XQR Series ... that would set quite a kick into the anthill, whilst extending the useful commercial lives of all these aircraft, with a nice boost to residual values ? Technically speaking "a piece of cake", said Adam Pilarski ! A better fate commercially speaking than P2F conversions ? Maybe AeroTurbo has up his sleeves a nice prospect for an engine revamp on top ?

  5. As I remarked, a "B757R" would be considerably larger. I don't see any version of it below 240 seats single class economy (ref: A321 in that layout at 200). Then of course a twin aisle. Today's single aisles will probably remain in production until a new technology becomes available that cannot be fitted on current single aisles, i. e. laminar flow wing or open rotor engines.