mz said:
I wonder if you just flew a 737 slower and with those new engines, how much it would make a difference?
There's been talk of re-engined 737s and A320s as a short term intermediate step for a couple of years now, now that both Boeing and Airbus are saying they won't have a new clean sheet single aisle design in service before the mid-20s at the earliest. That's easier for Airbus than for Boeing, this would be the 737's 3rd makeover/4th generation and there isn't much space between engine cowling and ground on the Boeing jet for a larger fanned engine. The speculation was running in favour of Airbus launching a programme sometime later this year, with Boeing likely forced reluctantly following, but there was some news coverage last week suggesting the financial case may turn out to be tighter than anticipated ($.5m per annum saving on a $3m purchase premium IIRC) and throw the idea of makeovers into question.
If the makeovers do happen then it won't be with any of the engines discussed in these articles, a short term programme (which this is) needs an engine ready for the big time and these aren't. The P&W PW1000G Geared Turbofan is in the running, it is going on the Bombardier C-Series and Mitsubishi Regional Jet that are snapping at the smaller end of the 737/A320 market and Airbus already had access to the flight test data because it was tested on one of their A340s, but the other engine manufacturers have counter proposals.
Longer-term we will see a new generation of aircraft with aerodynamics pushed further and entirely new engines. The improvements in emissions aviation has committed to mean that we need engines with much lower NOx emissions, not just improvements in fuel burn and the overall improvements need every part of aviation to play its part, aerodynamics as well as engines. But not just them, even how you move aircraft on the ground, the design of flights and how ATC works have parts to play. There are systems moving into trials that will move the aircraft to the runway without engaging the main engines by using either tugs or direct drive to the undercarriage. Equally flights can be optimised in both climb and descent to eke every bit of efficiency out of the system and trials for those have been running for a couple of years now and ATC has a role to play in redesigning airspace usage, allowing that optimisation to happen on every flight as well as eliminating fuel wasters like stacking.
WRT flying slower, yes, that does reduce drag costs, but there are other factors at play. The extra length of the flight is a commercial negative if your competitors are still flying faster, the longer sector duration may create issues for crew duty times and for aircraft utilisation. The finances behind aircraft mean they need to fly as many sectors as possible in a day and if flying slower means you can't fit in even a single sector you used to be able to then the financial consequences may stop the idea dead.
