Strathpeffer
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A Future For Big Turboprops?

Mon May 28, 2007 10:17 pm

Yesterday, whle waiting for my flight from LHR to ABZ, I was wondering whether we might expect to see a new breed of large turboprops in the future.

Given a background of increasing fuel prices and growing pressure to cut carbon emissions (fairly or otherwise, the air transport industry is under increasing scrutiny from the green lobby), an aircraft family seating 80 to 130 passengers and optimised for stages of 1-2 hours would seem to offer advantages.

What do you think?

PJ
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Glareskin
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RE: A Future For Big Turboprops?

Mon May 28, 2007 10:20 pm

There are still rumors for the next generation 737 / A320 to come with the unducted fan.
http://www.airliners.net/discussions/tech_ops/print.main?id=164698
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Strathpeffer
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RE: A Future For Big Turboprops?

Mon May 28, 2007 10:28 pm

Yes, I saw that and that was what put me on the trainline of thought.

I wondered whether there was some subtle difference between the UDF and a 'normal' turboprop - wouldn't a UDF plane be as fast as a current turbofan? What about fuel burn? There is also the advantage that TP technology is proven in service.

That's why I was think about really short hops - the kind where the speed tradeoff would be less noticeable and airlines are already using fast props like Saab 2000s or Dash 8 400s.

PJ
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srbmod
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RE: A Future For Big Turboprops?

Mon May 28, 2007 10:47 pm

Pundits thought that the regional jet had killed the turboprop, but this was when was still cheap. The 50 seat regional jet is a nearly dead market as a result of higher operating costs cutting into margins that are getting thinner and thinner due to increased oil prices and competition in some markets.

I think that anything larger than the ATR-72 and Dash 8-400 isn't really going to fly even in today's market place. Anything larger than those a/c aren't going to appeal to passengers regardless of any claims of being more environmentally friendly than a 737 or A320. Unfortunately, any airliner with propellers (regardless of it being a 19 seater, a 30 seater, a 50 seater or a 70 seater) has a negative impression with some fliers, as they equate propellers=old, which for us plane nuts know isn't exactly the case.

In the case of a number of airlines, ditching their turboprops for regional jets was more of a prestige thing than an economic thing. Small towns love saying "We have non-stop jet service to XYZ" (Flashbacks to the early days of the jets there when having jet service to your airport was a big deal) as it gives the impression that you won't have to fly on some rattletrap turboprop (Which is probably not the case in most instances) to fly to here.

One advantage regional jets have over the larger turboprops is that you can park more of them in the same amount of space. The way the parking spaces were set up on some of the gates on C when I was working there about 7 years back, you could park 3 or even 4 CRJ-200s in the same amount of space used to handle 1 ATR-72 flight.
 
Poitin
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RE: A Future For Big Turboprops?

Mon May 28, 2007 11:03 pm

[quote=Glareskin,reply=1]There are still rumors for the next generation 737 / A320 to come with the unducted fan.


I think one should look at the unducted fan as a turbo prop. The problem with these beasts is the noise they make. The NASA tests about 20 years ago on unducted fan engines showed good performance and terrible noise, but since that time the active noise cancellation (ANC) technology has advanced from earphones to systems that can reduce noise on the inside of the airframe such as in the Q400. The A400M, although a military aircraft, will have ANC, which may make the A400M a good place to start in designing the next generation of short haul aircraft.

Take a good look at the A400M specs to see what I mean

http://www.airbusmilitary.com/specifications.html

http://www.airbusmilitary.com/performance.html
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Strathpeffer
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RE: A Future For Big Turboprops?

Mon May 28, 2007 11:35 pm

Quoting Poitin (Reply 4):
The problem with these beasts is the noise they make.

I thought the noise problem with UDFs was outside the aircraft - this cannot be so easily controlled yet, or can it?

PJ

[Edited 2007-05-28 16:36:54]
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TheSorcerer
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RE: A Future For Big Turboprops?

Tue May 29, 2007 12:01 am

The SAAB 2000 had some sort of noise control system, didn't it?
Some sort of signal generator that went at a frequency which cancelled out the vibrations from the engines, or something along those lines.

Am I the only to remember that?  Smile

thanks

Dom
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philb
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RE: A Future For Big Turboprops?

Tue May 29, 2007 2:10 am

I saw the MD-80 UDF demonstrator at Farnborough and, from the outside, it wasn't particularly noisy - the problem was internal noise and some vibration down the back end due to the proximity of the contra rotating blades to the airframe.

A mid or overwing mounting could do away with those problems.
 
Poitin
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RE: A Future For Big Turboprops?

Tue May 29, 2007 2:22 am

Quoting Strathpeffer (Reply 5):
Quoting Poitin (Reply 4):
The problem with these beasts is the noise they make.

I thought the noise problem with UDFs was outside the aircraft - this cannot be so easily controlled yet, or can it?



Quoting Philb (Reply 7):
I saw the MD-80 UDF demonstrator at Farnborough and, from the outside, it wasn't particularly noisy - the problem was internal noise and some vibration down the back end due to the proximity of the contra rotating blades to the airframe.

A mid or overwing mounting could do away with those problems.

I think Philb is correct, but I have flown in enough turboprops to know that they are NOISY inside. The MD-80 UDF was very noisy for the reasons he gives.

All that said, go take a flight in a Q400 which has ANC and see just how quiet it can be. In sort, the noise can be controlled, but it must also be controlled for the turboprop to become popular.

I expect the A400M to be an important design for those reasons.
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