Rolls-Royce tests 'game-changing' greener UltraFan engine
bbc.com
bbc.com
I suspect that the ability to handle pure Sustainable aviation fuel (SAF) is the critical improvement here, but the article doesn’t provide the context that:
- current engines can only run with 5% SAF
- airlines are trying to get as much SAF as they can but struggle to find more at an affordable price
- how much SAF we could make based on current food trends and what is blocking us from reaching that level.
The announcement phrased as it is makes sense for professionals, which is why I understand RR PR department has phrased it that way, but the BBC shouldn’t expect its readers to know all that.
Suppose you want to reduce carbon emissions by 50% but SAE cost 40% more. Replacing half your fuel with SAE = 0.5 * 140% + 0.5 * 100% = fuel costs go up by 20% and ticket prices go up by half that or 10%.
If instead you reduce total fuel need by 10%. 10% engines + 40% SAE + 50% normal = 50% carbon savings. But you’re paying 0.1 * 0% + 0.4 * 140% + 0.5 * 100% = 6% more on fuel and ticket prices only go up 3%.
On top of that you don’t need to carry as much fuel which further increases efficiency or let’s you increase cargo capacity.
Winglets cut fuel consumption by 4-6% and literally changed the game.
I’m not sure that 10% would justify switching to a new engine, a new airplane type, and investing in re-qualifying all your pilots. I remember hearing hesitation around RISE and braced wings. Those would “only” save 20% fuel but required too many changes to be adopted before planes needed to be replaced.
On the other hand, working with a different fuel but with a similar power package, that could presumably be adopted before 2030, if the savings are indeed almost an order of magnitude of carbon footprint. This is why I think the article should have said a lot more about the supply chain and price of SAF.
Retrofitting winglets on an airliner costs a million+ upfront and grounds the plane for a week.
It’s not to the level of buying a new plane, but this is not a few hours work on the tarmac between two flights, they’re not airfoils off of wish you glue onto your rust bucket.
Try 14+ days for commercial aircraft.
Edit: this is answered down thread, seems it's more complicated than that.
Just to add - 10% increase on the state of the art is nothing small!
[1] - https://www.gov.uk/government/news/royal-air-force-completes...
There seems to be issue with the relative portion of octanes, so it cannot be used in large portion in both car and aviation: I remember reading something about lead in petrol and “knocking”, ie the air-petrol mix exploding too early. I’m assuming that this engine handles that problem better, somehow. Given that lead is still in aviation gas, that would be beneficial in many ways.
If McDonald's and other similar food joints of the world were be able to power not just trucks, but also airlines with used cooking oil, this would be something :)
Oh, and a 10% efficiency improvement over the current most efficient turbine engine, nice. This may be a bigger feat of engineering than the use of SAF, but looks less catchy.
There are still sources of vegetable oil to be had, but they are not used oil.
https://pledgetimes.com/the-odyssey-of-recycling-cooking-oil...
Biodiesel is barely carbon-neutral if you're lucky; often it produces more carbon dioxide than you'd emit if you just used all the fuel directly, instead of fueling the agricultural machines, fertilizer factories, etc [1].
When all the harvesters and presses become 100% powered with renewables, direct production of biodiesel may make sense.
[1]: https://theconversation.com/biofuels-turn-out-to-be-a-climat...
Apparently this new engine is 10% more efficient, and also runs on “Sustainable Aviation Fuel” (SAF). I did some quick searching, and this source claims that SAF can reduce carbon emissions by “up to 80%”, and that this improvement might represent 65% of the necessary decarbonization of the aviation industry [1].
[1]: https://www.iata.org/en/programs/environment/sustainable-avi...
Given the expected price point of the car brand, they can afford very interesting exploration in the EV space. They’ve revealed some prototypes but haven’t really owned the space the way they could: silent, heavy, and stately with surprising power if needed—EVs are a perfect match for their brand.
RR is the leading airplane engine manufacturer with Honeywell and Pratt & Witney. GE & Safran contribute a lot too, but usually for specialized (military) applications. Unless something goes wrong, this engine could easily equip the majority of Boeing and Airbus that fly in 2030. I’d agree with your implicit assumption that it could be on 80% the commercial aviation.
I’m not sure what their source is but it says this is the commercial market, excluding military and private aviation.
1. https://www.statista.com/statistics/1099835/global-aircraft-...
Does this imply retrofitting existing planes with the new engine? Is that a common task / how expensive is it? I can’t find any info online.
Not sure what fitting a different engine type would do to the (re)certification/airworthiness though, that might introduce a whole other bunch of bureaucratic difficulties.
Re-engining is a medium program requiring recertification (as lots of ancillary components need to be replaced to match, and the physical properties of the plane almost always change e.g. shape, size, and weight will change the plane aerodynamics), hence they generally include minor frame updates (e.g. A320neo), but can also require pretty major redesigns (737-NG, 737-MAX).
Plus it's common for the engine to be customised to the frame e.g. the CFM LEAP 1A is the variant for the A320 neo, the 1B for the 737 MAX, and the 1C for the COMAC C919. Similarly, the A220, A320neo, Embraer E2 and Irkut C21 all use different models of the PW1000G family.
As in switching an A320neo from P&W to CFM, not switching an A320 to a LEAP that’s never been an engine option.
GE and Safran is CFM (https://en.wikipedia.org/wiki/CFM_International), in late 2021 CFM claimed they had 72% of the narrowbody market. Literally all the 737 MAX mess was so they could re-engineer it for the LEAP and avoid falling too far behind the A320neo, and the CFM56 remains extremely popular despite its age.
Also things might get quite weird if RISE is a success.
Very roughly a plane emits CO2 equivalent of using 1MW of electricity per passenger in economy. So an intercontinental return flight can be equivalent to a whole's years worth of electricity usage....
But just to put things in perspective; all of aviation contributes up to only 2.5% of all global emissions (both direct and indirect).
A model turbofan might have a bypass ratio of 10, aka for every kilo of air going through the core 10 are pushed around it by the fan.
That applies to all airliners e.g. the reason for the 737 max’s issues is that the plane is very low to the ground, so it didn’t have room under the wings for modern turbofans.
The 2nd and 3rd gen 737 (Classic and NG) worked around it with peculiar flattened nacelles (they’re circular on every other plane), and moving some of the components to the sides (from their usual position at the bottom).
For the Max Boeing wanted even wider engines, and there was no way to flatten things further, so they moved the engines forwards and using long struts (check out comparison pics from the side).
The result however is that the thrust vectors are different than on “normal” 737 giving the aircraft a tendency to pitch up in certain conditions, which is what the MCAS was supposed to automatically remedy.
For reference, the original 737 had engines with a width of ~1m (40 inches), the second generation (“classic”) had fans 1.5m (60in) in diameter, the 737-NG is a minor bump to 1.55m (61in).
The Max’s CFM Leap has a 1.76m (70in) fan. And that’s a specially reduced and less efficient version, on the 320neo the same engine has a 2m (78in) fan.
https://aviationweek.com/aerospace/aircraft-propulsion/rolls...
Notable: The fan is driven through gearing from the low-pressure turbine stage.
> ... with its power gearbox and Advance3-based core, represents a radical shift away from the traditional three-shaft designs that have been the hallmark of Rolls-Royce’s large engine configurations since the 1960s.
> Newby says. “For example, we’ve developed a new way of rapidly developing software which we’re going to use on the Pearl 10X [business jet engine].
Now that sounds scary.