Leeham News and Analysis
There's more to real news than a news release.
Leeham News and Analysis
- Boeing CEO promises company is turning around…again April 24, 2024
- Solid start for stand-alone GE Aerospace despite cuts to LEAP output April 23, 2024
- SPEEA, Boeing at impasse over safety program, union says April 23, 2024
- Better transparency needed on Boeing’s 1Q earnings call April 22, 2024
- Bjorn’s Corner: New engine development. Part 4. Propulsive efficiency April 19, 2024
PW Media Day 1: next gen GTF to cut fuel costs 10%-15% over today’s GTF
We’re at the Pratt & Whitney media days today and tomorrow. This is the Technology at PW panel. Participants are:
Alan Epstein, engineer and moderator. (AE)
Michael Winter, chief technologists (MW)
Graham Webb, MRJ, CSeries and EJet engines. (GW)
Jimmy Kenyon, advanced military programs. (JK)
All information is paraphrased.
GW: At $4/gal, over 60% of cost to an airline is for fuel. Engines must cut these costs. A380 and 787 consume less than 3 liters per passenger, about that of a compact car.
GTF is certified [on CSeries]. GTF now on five airframes with 12 sub-types. The engine reduces fuel and maintenance costs, reduced emissions. Fuel savings now demonstrated at 16% less than today’s engines.
Next generation of GTF will further reduce fuel burn by 10%-15%.
MW: The noise footprint will stay predominately within the airport boundaries, using 2,000 fewer foils, about half of our competitor’s engine. Emissions are about 50% below current regulations and working with NASA toward 88% below current levels.
Current bypass ratio about 13:1 and currently testing with NASA 15:1 and 18:1.
375% improvement in efficiency since the days of the Whittle jet engine.
We have the most advanced cooling system in the industry and we are exploring inserting advanced materials into the engines when there is real benefit to the customer.
JK: We’re seen similar trends to improve efficiency in military as with commercial. The Department of Defense is the biggest user of energy in the country, with about 80% in engines.
The military has seen really tight budgets in recent years. There is more than just a cost issue, it’s also an energy security issue (Iraq, Afghanistan challenges). There is a real interest in cutting energy usage and aviation being such a large part, it is a natural place to look.
The strategy considers places where you have to fly farther and/or stay on station longer. We’re working on technology to provide fuel management and efficiency to reduce costs, fly father and stay on station longer.
We’re working with USAF to obtain 25% improvement in fuel efficiency on next engines, and with Navy to also improve efficiency, and leveraging work in the commercial arena to improve thermal efficiency.
AE: Are you a one-trick pony? What have you got besides the gear?
GW: We have advanced fan module, bringing forward light weight fan cases, the next generation combustor, advanced core, state-of-the-art high pressure turbine and high speed low pressure turbine, all of which designed for the very high speeds. There are control system enhancements, working on next gen of the fan-drive gear system, short inlets for enhanced efficiency.
GE engines faces challenge from PW, RR GTF technology
The recent announcement by Rolls-Royce that their future engines will contain gearboxes has put GE and its CFM partner SAFRAN under considerable pressure.
GE/SAFRAN were together with Rolls-Royce proponents to go directly from Direct-Drive turbofans to Open Rotor designs for the next generation aircrafts. This left Pratt & Whitney as the only major engine manufacturer promoting high by-pass ratio geared turbofans as a better alternative for these aircrafts. With the Rolls-Royce announcement of Advance for 2020 (Carbon fanned tri-shaft) and Ultrafan (Geared big fan) for 2025, this has all changed. Suddenly Pratt & Whitney has strong support in their strategy and GE/SAFRAN stand out as loners.
By honing key technologies in their traditional two shaft turbofans GE, and GE/SAFRAN in CFM, have built a market leading position in all thrust classes, Regional (CF34), Single Aisle (CFM56) and Dual Aisle (CF6, GEnx, GE90). Their declared next step was Open Rotor for future Single Aisle while keeping Direct-Drive for larger engines.
Airbus and Snecma continue to research open rotor technology. Aviation Week has this story.
Now this solid position is threatened. The geared architecture has won the future regional market (CSeries, MRJ, E-Jet E2 goes PW GTF), market parity on the A320neo family and the 757 replacement studies by Boeing (dubbed NAS, New Airplane Study) will not go Open Rotor as Open Rotor only works up to M 0.75 and the 757 replacement will likely fly over 4,000nm, necessitating higher cruise speed. The NAS will thereby favor a geared turbofan instead of Open Rotor. Why not Direct-Drive? There are two major reasons:
- A geared design allows higher by-pass ratios and thereby higher propulsive efficiency without the engine being too heavy from its large low pressure turbine needed to drive a high BPR fan.
- A geared design can allow the big fan to rotate slowly and with a low pressure ratio. This creates a low noise engine, a very important feature for aircrafts operating out of noise troubled airports.
GE/SAFRAN has shown with their CFM LEAP project that they can match the efficiency levels of a geared engine like Pratt & Whitney’s GTF, using its superior hot section technology to achieve the high efficiency. It cannot achieve the low noise levels of a geared fan however; engine noise stands in direct relation to fan rotational speed and pressure ratio.
It will thereby be the environmental factors that will put the most stress on GE/SAFRAN’s present strategy. Having lost the regionals to the geared camp, will it also lose the next generation short/medium haul? It will be interesting to watch the GE/SAFRAN over the next 18 months: does it change strategy or not? If one goes by the recent words of GE Aviation President David Joyce (who spoke at last week’s opening of their Indiana LEAP factory), he thinks his present line-up is fine for a 757 replacement, and he sees no urgent need for new developments.
By Leeham Co EU
Rolls-Royce plans for new single-aisle, twin-aisle airplane engines
Rolls-Royce may not be at a cross road but it’s certainly at a fork in the road.
RR sought to be a dual-source supplier for the Boeing 777X, competing with GE Aviation for the privilege; it was generally a given that GE would be a provider. The question was whether it would be the sole supplier or share the platform with another. Pratt & Whitney withdrew, concluding the business case wasn’t there for its proposed big Geared Turbo Fan. RR stayed in the competition, assured by Boeing that it wasn’t a stalking horse to GE.
But GE won the position as exclusive supplier, much to RR’s consternation.
Next, the future of the Airbus A350-800, powered exclusively by RR, is in serious doubt. The backlog is now down to a mere 46 as customer after customer, encouraged by Airbus, up-gauged to the A350-900 and -1000 sub-types. While RR is also the exclusive supplier on each of these models, and the engines are largely common, there has been substantial investment by Rolls on the -800’s application. If the -800 is canceled (as many industry observers believe it will be), RR’s investment is largely down the drain. How does Airbus “make good” to RR for this?
Odds and Ends: Rolls follows Pratt with GTF technology; Airbus’ challenge;
Rolls-Royce and GTF: Rolls-Royce today said it will pursue technology for its next big engine that follows the Geared Turbo Fan technology of Pratt & Whitney’s smaller design.
Aviation Week has this story and Bloomberg has this one.
RR says the engine will be ready around 2020, which is just about the time Emirates Airlines would like to see an engine that is 10% more efficient than today’s technologies, for the Airbus A380.
Airbus’ challenge: Reuters has a think-piece about the challenge Airbus faces in the heart-of-the-market twin-aisle sector occupied by the A330 and A350. Bloomberg discusses the A350 challenge in its report of Airbus Group earnings.