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RR Undertakes Secret Study Into Open Rotors  
User currently offlineParapente From United Kingdom, joined Mar 2006, 1548 posts, RR: 10
Posted (5 years 9 months 1 day 6 hours ago) and read 7343 times:

Flight Global Wednesday

http://www.flightglobal.com/articles...nto-public-perception-of-open.html

There have been an increasing amount of articles surrounding the "new engines" subject. Indeed today we see the GTF taking off on an Airbus. It seems that Rolls are nearing the point (when all patents are in place) when they are going to show the World how they have managed to design a quiret Open Rotor. That they have can be in no doubt or they would not be publicly saying what they are in this and many other recent articles.

The silence from GE is deafening. I feel sure that they have gone down the same route as Rolls (and I bet they have cracked the noise issue too).

All of which is mucho bad news for Boeing and Airbus.They don't want to have to design 2 new airliners -which for open rotor they would have to. That is why we see the GTF in the air today and Boeing 737 illustrations with GTF "yesterday".

Well I have bad news for these 2 "bedfellows". When GE and RR reveal their designs -with the consumer acceptancy research -with the 25% lowered fuel consumption -they are going to have to.

43 replies: All unread, showing first 25:
 
User currently offlineNicoEDDF From Germany, joined Jan 2008, 1098 posts, RR: 1
Reply 1, posted (5 years 9 months 1 day 4 hours ago) and read 7189 times:

Open Rotor...hell yeah...nothing more sexy engine wise than that.

Regarding GE: Maybe they have not yet cracked the noise issue or rather the full performance package of noise-power-SFC trade off is not satisfying.
Why should they be so quiet if theres something to be proud of?

I could imagine that P&W is going to provide the near to mid term engine, not only for new jets but also for re-engining the huge fleet of todays NB. I venture to say that at least 10 years will pass before an open rotor concept is at a decent level of power, noise (or better silence), SFC and operating reliability to be a valuable engine. Absolut in time then for any NB replacement. And if you consider that probably the new NB airframe concept would look different from todays (at least I hope so) even more time will be for the engine OEMs to mature the engine.

But maybe...I am totaly off  Smile


User currently offlineKeesje From , joined Dec 1969, posts, RR:
Reply 2, posted (5 years 9 months 1 day 4 hours ago) and read 7149 times:

Many tests have been done during the last 12 months, including noise modelling tests in tunnels.



Two engines, the new RB282 and RB285 could become a basis of RR 'Option 15-20' which won't be an open rotor, but could also provide a core for 2 or 3 shaft 'Option 30' open rotor designs. So they are betting on 2 horses..


User currently offlinePliersinsight From United States of America, joined May 2008, 488 posts, RR: 0
Reply 3, posted (5 years 9 months 1 day 3 hours ago) and read 7063 times:

Are there any specific concerns with such engines that anyone might be aware of, e.g. icing, bird/object strikes, dangers to ground crews, core lock, wake turbulence, that would differ from conventional designs?

User currently offlineORDagent From United States of America, joined Dec 2003, 823 posts, RR: 1
Reply 4, posted (5 years 9 months 1 day 3 hours ago) and read 7050 times:

IIRC a similar concept called an unducted fan was shelved due to noise issues. Also Joe Traveler has a concept that dislikes "prop" aircraft.

User currently offlineClydenairways From Ireland, joined Jan 2007, 1222 posts, RR: 0
Reply 5, posted (5 years 9 months 1 day 2 hours ago) and read 6924 times:



Quoting ORDagent (Reply 4):
IIRC a similar concept called an unducted fan was shelved due to noise issues. Also Joe Traveler has a concept that dislikes "prop" aircraft.

Yep, i think there was both noise and vibration issues inside the cabin.


User currently offlineClydenairways From Ireland, joined Jan 2007, 1222 posts, RR: 0
Reply 6, posted (5 years 9 months 1 day 2 hours ago) and read 6897 times:


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User currently offlineParapente From United Kingdom, joined Mar 2006, 1548 posts, RR: 10
Reply 7, posted (5 years 9 months 1 day 1 hour ago) and read 6827 times:

I think you will find that RR (and GE) are more than aware of the (above mentioned) problems to be over come.What is interesting about this and recent articles is that clearly RR (at least) believe that they have overcome them.

No one (even P&W) accept that the economies of this technology are the best out there. If oil is at "peak" the $100 will return as sure as night follows day.And since energy density is critical to things that fly (as opposed to cars for instance) they will continue to be powered by fossil fuels.

Clearly RR are not yet able to let all the cats out of the bags -so I guess not a thread that can go far -yet. But I for one am really interested to see just what they have come up with -and indeed what type of aircraft design would suit them best.

Much as I applaud Easy Jet for trying I cannot take their open rotor design seriously. I am sure they did it just to give Boeing and Airbus a prod in the right direction!


User currently offlineAA777223 From United States of America, joined Feb 2006, 1227 posts, RR: 6
Reply 8, posted (5 years 9 months 23 hours ago) and read 6687 times:

Well, I guess they were secret until you blew the lid off the top on the internet, haha!


Sic 'em bears
User currently offlineKeesje From , joined Dec 1969, posts, RR:
Reply 9, posted (5 years 9 months 9 hours ago) and read 6464 times:

As you can see the design of PW in the eightes had a similar number of blades in the front and rear rotor. You won't see that in later designs.

The diameters of the rotors, shapes and profiles of the blades of current designs are much more optimized with the help of advanced fluid dynamics.

Maybe more noise becomes more acceptable in the total trade-offs if oil hits $200 /barrel. New wing tail configurations are developped to shield of noise.

Environmental pressure will rise too. The polar bears don't die because of noise around our hubs.


User currently offlineImperialEagle From United States of America, joined Jan 2006, 2429 posts, RR: 23
Reply 10, posted (5 years 9 months 8 hours ago) and read 6386 times:
Support Airliners.net - become a First Class Member!



Quoting Parapente (Reply 7):
to give Boeing and Airbus a prod in the right direction!

It won't be the first time an engine manufacturer has created a situation that forces the airframe manufacturers (kicking and screaming) to change. It just doesn't happen often. Obviously RR is going to "scare their mule" but good.




Maybe more noise becomes more acceptable in the total trade-offs if oil hits $200 /barrel. New wing tail configurations are developped to shield of noise.

Environmental pressure will rise too. The polar bears don't die because of noise around our hubs[/quote]

As usual "Keesje" is right on top of it.
Even at a slow pace we all knew this type of design would continue to evolve.
Perhaps "Keesje" will give us an updated airframe example of his design to see what the finnished product might look like------------?



"If everything seems under control, you're just not going fast enough!"
User currently offlineKeesje From , joined Dec 1969, posts, RR:
Reply 11, posted (5 years 9 months 8 hours ago) and read 6370 times:



Quoting ImperialEagle (Reply 10):
Perhaps "Keesje" will give us an updated airframe example of his design to see what the finnished product might look like------------?

You have a good nose.. last yr I was working on something with Henry Lam & then we got busy with other things. It still on the to do list. Sneak preview :



User currently offlineRevelation From United States of America, joined Feb 2005, 12286 posts, RR: 25
Reply 12, posted (5 years 9 months 4 hours ago) and read 6201 times:



Quoting Parapente (Reply 7):
Clearly RR are not yet able to let all the cats out of the bags

Yet they seem to have the need to say something, since everyone can see the PW GTF demonstrator flying around on the A340 prototype.



Inspiration, move me brightly!
User currently offlineParapente From United Kingdom, joined Mar 2006, 1548 posts, RR: 10
Reply 13, posted (5 years 9 months 4 hours ago) and read 6146 times:

Re Revelation. I am sure you are right. The GTF offers Boeing/Airbus the (very) easy way out (particularly in a recession). RR are tying to ensure that the World knows that there ia a far more efficient technology just around the corner (clearly one that Easy Jet wants and thats not to be sniffed at if you are a European at least). But as Keesje so amply shows (and indeed Boeings Muppet jets) real improvement will require a new and totally integrated approach. I don't imagine that RR is in any particular hurry, just as long as B & A don't go for the "quick fix" short term option.

User currently offlinePar13del From Bahamas, joined Dec 2005, 6987 posts, RR: 8
Reply 14, posted (5 years 9 months 3 hours ago) and read 6102 times:



Quoting Parapente (Thread starter):
All of which is mucho bad news for Boeing and Airbus.They don't want to have to design 2 new airliners -which for open rotor they would have to. That is why we see the GTF in the air today and Boeing 737 illustrations with GTF "yesterday

Unless I missed something, both OEM's have said that they were not building new narrow body a/c because engine technology had not yet risen to a point to make the current model inefficient, with an increase in the 10-20% range.

Airbus in modifying their A320 to include the PW offering is a project under consideration, Boeing has since said they would look at the B-737 also, somehow I don't see this as them not being interested in offering products, if you were talking about GE not offering an engine for the A-350 then I would agree.


User currently offlineKeesje From , joined Dec 1969, posts, RR:
Reply 15, posted (5 years 9 months 3 hours ago) and read 6046 times:



Quoting Par13del (Reply 14):
Airbus in modifying their A320 to include the PW offering is a project under consideration, Boeing has since said they would look at the B-737 also, somehow I don't see this as them not being interested in offering products, if you were talking about GE not offering an engine for the A-350 then I would agree.

I think the airlines have been putting pressure on the industry to come up with (20%) better aircraft. The 737 and A320 are cash cows for Airbus and Boeing with enormous backlogs.

The industry is putting all their resources on A320F, A350, A380, 787, A400, 747-8, 777 upgrade, A330F, GTF, CSeries, MRJ, Superjet, MS-21.

Disagreement between OEMS and airlines is growing IMO. A&B said after 2020, airlines asked ASAP & don't agree it is only possible in 2020.

Bombardier might become the winner, the Cseries provides a good platform for 150 seats. A lighter airframe optimized for 150 seats <4hr flights & GTF could convince airlines.


User currently offlineAirbusA6 From United Kingdom, joined Apr 2005, 2006 posts, RR: 0
Reply 16, posted (5 years 9 months 2 hours ago) and read 5977 times:

In a world where tubes with 2 fans under the wings is the norm, and selling in incredible numbers, it will be a mega brave decision for A and B to go for something radically different...

Funnily, if MDD had still been in business, then they would have found it much easier to install the open rotor engine, and perhaps we would be looking forward to the DC9 for the 21st century, the open rotor powered MD100!



it's the bus to stansted (now renamed national express a4 to ruin my username)
User currently offlineAlessandro From , joined Dec 1969, posts, RR:
Reply 17, posted (5 years 9 months 2 hours ago) and read 5955 times:

Perhaps on cargohaulers, but I doubt make it to the passenger planes.
Yakovlev and Tupolev also got a bunch of paperplanes with open rotors.


User currently offlinePar13del From Bahamas, joined Dec 2005, 6987 posts, RR: 8
Reply 18, posted (5 years 9 months 2 hours ago) and read 5947 times:



Quoting Keesje (Reply 15):
Bombardier might become the winner, the Cseries provides a good platform for 150 seats. A lighter airframe optimized for 150 seats <4hr flights & GTF could convince airlines.

You may be right, but I will have to see that to believe it, OEM's presently want to upsize everything, they are for the most part looking to abandon the 100-150 seat market, or at least have their a/c optimized for the higher end. It would certainely take an airline with brass to abandon their A320 / B737 fleet, but you never know, stranger things have happened.


User currently offlineAreopagus From United States of America, joined Sep 2001, 1369 posts, RR: 1
Reply 19, posted (5 years 9 months 1 hour ago) and read 5872 times:

So what's next -- an open propeller rotor driven by a turbocompound engine?

User currently offlinePlanemaker From Tuvalu, joined Aug 2003, 6076 posts, RR: 34
Reply 20, posted (5 years 9 months 1 hour ago) and read 5826 times:



Quoting Parapente (Reply 7):
If oil is at "peak" the $100 will return as sure as night follows day.

Oil is not at peak... far from it. However, oil has been near peak production. However, if politicians show some true leadership we could quite quickly move away from our oil addiction. I am hopeful but I am not holding my breath.



Nationalism is an infantile disease. It is the measles of mankind. - A. Einstein
User currently offlineImperialEagle From United States of America, joined Jan 2006, 2429 posts, RR: 23
Reply 21, posted (5 years 8 months 4 weeks 1 day 20 hours ago) and read 5645 times:
Support Airliners.net - become a First Class Member!



Quoting Keesje (Reply 11):
Sneak preview :

Oooooooh----I want to see more. I'll have to pay attention so I won't miss them!



"If everything seems under control, you're just not going fast enough!"
User currently offlineDocLightning From United States of America, joined Nov 2005, 19278 posts, RR: 58
Reply 22, posted (5 years 8 months 4 weeks 1 day 20 hours ago) and read 5605 times:

People keep talking about "public opinion" and "public acceptance" of these designs.

Huh? Back in the late '90's when the 772ER started to fly, ETOPS became a concern and a topic of public debate. During this time VS bought A340's in lieu of the 777 because Branson wanted a marketing campaign of "4 engines 4 long haul."

Turns out that the public didn't care much. The 777 won the game. And I mean by a lot.

When Joe Traveler buys a ticket aboard an airline to fly from A to B and shows up at the airport, he may or may not have an opinion of the plane. If he doesn't want to fly it, then he has two options: he can refuse to board and forfeit his ticket or he can fly aboard the plane and swallow his pride.

But if this design is as economical as it sounds, he's going to quickly find that if he wants to fly, he's going to be flying on planes with open rotors.

Now, what I don't get is why an open rotor is so much more efficient than a ducted one.


User currently offlineZWZWUnited From United States of America, joined Jun 2008, 197 posts, RR: 0
Reply 23, posted (5 years 8 months 4 weeks 1 day 19 hours ago) and read 5550 times:

With many aircraft manufacturers shying away from rear-mounted engines, would it be possible to have a UDF engine under wing? Could these engines be limited in this sense (only fuselage mounted)?

~Tim  Smile



Drop it like its hott!
User currently offlineDocLightning From United States of America, joined Nov 2005, 19278 posts, RR: 58
Reply 24, posted (5 years 8 months 4 weeks 1 day 19 hours ago) and read 5518 times:



Quoting ZWZWUnited (Reply 23):
With many aircraft manufacturers shying away from rear-mounted engines, would it be possible to have a UDF engine under wing? Could these engines be limited in this sense (only fuselage mounted)?

An airliner is designed to be as economical as possible. If it turns out that the UDF offers enough of an advantage to offset the increased costs of rear-mounted engines, then that's where they'll put them.

But remember, turboprops have a fan diameter that is similar to that of a 1st generation high bypass ratio turbofan. The engines are mounted above the wing to give them enough ground clearance on those little planes. The props extend both above and below the wing and this causes no serious problem.

In the case of the UDF, the engine could be mounted below the wing with the fan projecting ahead of the wing. The sweep of the fan could very well extend above the plane of the wing.

Now, if the UDF uses a rear-mounted rotor like the GE prototype from the '80's, then this would not be an option.


25 ZWZWUnited : That is what I was getting at. Do they tend to lean towards rear-mounted rotors? Would they be able to efficiently engineer a forward-mounted rotor?
26 DocLightning : Ask RR. I don't think they're in much of a talking mood, though.
27 Lightsaber : So true. I know RR is seriously looking into GTF concepts. Open rotors have their place. On relatively short missions. (e.g., within Europe.) But the
28 DocLightning : Good point. What do you do about a fan blade failure? I mean, I guess turboprops don't have a containment ring, either... You mean, this is why all n
29 MD-90 : They wouldn't because they need aircraft that size. They just wouldn't be Boeings or Airbuses if they didn't offer them.
30 AirbusA6 : It's also worth noting that both RR and GE have invested heavily in wide bodied engines recently (Trent 900, 1000 & XWB, GE90-115, GEnX etc) whereas
31 Parapente : As Airbus A6 states on a typical 2 -3 hour flight the speed differental in a non issue. But really the only point is whether A&B wish to design new ai
32 Phollingsworth : It is really more like .78 to .72 or 0.06 Mach. The real issue with the open rotor is not the long segment lengths but the inability of the ATM to ha
33 Revelation : I agree 100%. I would have guessed (3). Thanks for the wonderful tutorial! With regard to containment, it seems with the open rotor, we'll have to se
34 ContnlEliteCMH : I'm thinking like you are. The wildcard in all of this is the GTF's performance and reliability but we're much closer to knowing that now! I'm seriou
35 Lightsaber : WIth open rotors, its going to be an issue that drives engine placement. Its about blade energy. On the larger turbofans/GTF, an un-contained blade w
36 Leezyjet : Wasn't Branson's marketing campaign, it was an Airbus slogan and as VS was the launch customer for the A346, adopted it too. If it had been a VS slog
37 DocLightning : Ah. I didn't know that. Still, when I board one, I do everything I can to ensure that I'm not sitting right next to the prop. If it's going to come s
38 Post contains links Tdscanuck : I'm not sure that's a requirement...turboprops have thrown blades through the cabin before, so I'm not sure we can realistically enforce that require
39 Lightsaber : You know, almost no engine engineers (excluding myself) will sit next to the engines... 1/3rd of a rotor went right through the cabin once and a moth
40 Post contains links and images Keesje : I avoid some hot high rpm things 2 rows back too.. FYI this disk is visiting its brother in the the other engine cutting the belly like butter
41 Lightsaber : Thank you for that statement. Otherwise I would be suspicious of a failure at idle (the only way to partially escape and stay in its own nacelle). I'
42 Revelation : Thanks for your comments, Tom. Yep, I can imagine this is the way it'd go. It'd be cool to see a computer simulation of blade seperation in an open ro
43 Lightsaber : Due to the extreame bypass ratios , new designs would be required. Why retrofit an MD-80? They already consume 25% more fuel than a 738 (not to menti
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