AA737-823 From United States of America, joined Mar 2000, 6116 posts, RR: 10
Reply 1, posted (7 years 1 week 5 days 7 hours ago) and read 5133 times:
Quoting Keesje (Thread starter): Second thought, maybe this forum is not the right place to even suggest rationalization / shrinking iso growing the business
I did learn from the article, though. I never really considered that ULH routes employ inherent inefficiencies.
What I want to know is why they're content with such a high degree of compromise. They start at the 15% option, which they say basically should be accomplished by someone else. Namely, the operator, making a stop for fuel, and slowing down.
Then, to achieve the 50% option, they say that maintenance will be horrendous.
Okay, those ARE two viable options, but I predict the winner of the next narrowbody generation will be the manufacturer that provides the LEAST amount of compromise from the get-go. High efficiency would also seem to include not having to remove the engine every three days for overhaul, would it not?
I exaggerate, but you get the point.
If PW or GE or the alliances (IAE or CFM) can accomplish high efficiency without penalizing the maintenance aspects, they'll fare better.
That said, I'm a mechanic, so an inherently unreliable engine sounds like a great idea to me!!!
Zkpilot From New Zealand, joined Mar 2006, 4993 posts, RR: 9
Reply 2, posted (7 years 1 week 5 days ago) and read 4933 times:
This will be the option for airfreight and over shorter distances and for Low Cost type flights (if fuel goes up more). However there are already technologies being developed..in particular HST using Hydrogen (capable of flying up to mach 8 and able to fly SYD-LHR in about 4 hours). With Hydrogen not being dependant on oil and being clean burning (provided it can be produced cleanly ie carbon neutral) then this is the future of airtravel (albeit at a higher price point than todays historically cheap economy tickets).
Art From United Kingdom, joined Feb 2005, 3485 posts, RR: 1
Reply 5, posted (7 years 1 week 4 days 17 hours ago) and read 4548 times:
Quoting Keesje (Reply 4): I think speed & comfort are moving down the priority list.
The current consumer demands (a) speed (b) a low price.
Can't work. Airlines providing both (a) and (b) operate at a loss. The answer is not to provide the consumer with what he wants, run up massive losses, refinance or dump debt through bankrupcy and and then repeat the hopeless cycle. If the consumer will not buy at a viable price, the answer has got to be to offer a lower cost service (at a lower speed) at a price that the consumer is prepared to pay.
If that means technical stops on long hauls and using props for short haul, that's good. IMO it's good because it gives the airlines a chance to conduct their business on a sound financial basis.
Fuel savings could be achieved by using lighter components and operating the engine at higher combustion temperatures, in return for a reduction in time between overhauls.
"One per cent of fuel now is probably the same as about 10-15% of maintenance costs, depending on whether you're short range or long range," says King
The RR view seems to make sense to me - run the engines hotter to use less fuel at the cost of replacing components after a shorter time.
Personally I find the idea of ultra long haul flights somewhat grotesque if they are extremely inefficient when it comes to fuel burnt. I would like to see the manufacturers turn their attention to designing long haul aircraft that require a stop for fuel. Apart from some flights across the Pacific, what routes could not be flown using aircraft with a 5000 mile range?
Stitch From United States of America, joined Jul 2005, 32728 posts, RR: 85
Reply 6, posted (7 years 1 week 4 days 17 hours ago) and read 4529 times:
I think people want convenience, more then speed.
ULH non-stops have already proven themselves to be a very niche market.
One advantage of shorter hops is the ability to use MTOW for revenue payload and not fuel. The Middle East is exceptionally well-placed to handle EU to Oceania traffic as the distances are likely within their plane's range with maximum structural payload.
Asia-North America, alas, still needs long-haul non-stops - unless the US turns Midway Island into the next Dubai.
Rheinbote From Germany, joined May 2006, 1973 posts, RR: 52
Reply 7, posted (7 years 1 week 4 days 15 hours ago) and read 4407 times:
Funny how old wisdoms need to be re-invented over and over again. Rule of thumb is that an aircraft designed for 3000NM staging two flights for a total of 6000NM would use about 30% (THIRTY - give or take) less fuel than an airplane designed for flying 6000NM non-stop.
I'm sure there'll be replies aplenty pointing out that it's actually 20% or 40%, but in any case the savings would be substantial.
Even air-refueling after 3000NM would yield a saving - including the fuel burn of the tanker aircraft! If only it wasn't too dangerous for airline operations.
In the light of this, I think flying 8000NM non-stop is a folly, more so as the 787 doesn't quite make it (yet) and the A350 is likely to run into the same problems. In terms of flight physics, both design specs are borderline. And both design specs are driven by ULH niche players.
I think propfans are a blind alley. If you REALLY want to save fuel, then limit flying to begin with. If you want to go with propeller airplanes, then limit speed to what a 'standard' turboprop can handle. Say Mach 0,65, perhaps Mach 0,70 or what have you. Beware that flying slower also means flying lower, hence more drag and more flying 'around the weather', both adding to fuel burn.
Another issue is, the larger the aircraft, the larger the prop(s). This means that from a certain threshold point the prop(s) grow so large in diameter that you run into lots of engine/airframe integration problems. Then you either have to go to smaller contra-rotating props or to smaller props driven by more engines. Both bad for reliability and maintenance cost.
Regarding Keesje's favourite twin propliner powered by A400M engines: What's the single engine safety speed?
Keesje From , joined Dec 1969, posts, RR:
Reply 8, posted (7 years 1 week 4 days 15 hours ago) and read 4387 times:
Quoting Stitch (Reply 6): Asia-North America, alas, still needs long-haul non-stops - unless the US turns Midway Island into the next Dubai.
Maybe high fuel prices are "good news" for Narita.
Transforming one of the east Siberia AF bases into a gas station with a lot of runways, douches, bathrooms, tax free and cargo facilities also might be a good idea They have space, money and sit inbetween US and Asia.
But lets stick to the topic. Open rotors are on the table again. What was learned from earlier test & can be seen in the picture on top is that blade tip noise is critical. Not using the same number of blades on the two rotors, giving them different shapes and cross sections and balancing the distance inbetween helps. As descriped in the article RR is doing tests in a big tunnel in the Netherlands to measure noise and developing models to reduce it..