Dash9 From Canada, joined Nov 2008, 26 posts, RR: 0 Posted (5 months 1 week 5 days 23 hours ago) and read 15626 times:
hello
AFAIK as of now the largest turboprop available on the market are the Q400 and ATR72. Bombardier has been studying a possible strech called Q400x for some time and Embraer also talked of a possible new turboprop.
What specs would a new, bigger turboprop need to succeed against an equivalent sized jet? Speed, fuel economy, comfort, range? How likely it is that it could be based on an existing / planned frame such as the A320 or Cseries?
Thegeek From Australia, joined Nov 2007, 1012 posts, RR: 0 Reply 1, posted (5 months 1 week 5 days 23 hours ago) and read 15626 times:
I think the answer to this question is no.
Turboprops, even the Q400 are much nosier than jets, so they are disliked by pax, and they're also slower so they are only useful on short routes. If they're only good for short routes, then you need to have frequency. Most of the routes in Europe which could have used such a plane now have a train service, like BCN-MAD, and even the US has the Acela.
GFFgold From Indonesia, joined Feb 2007, 398 posts, RR: 0 Reply 3, posted (5 months 1 week 5 days 22 hours ago) and read 15453 times:
I see lots more potential for smaller turboprops in the developing world where urbanisation has outstripped surface transport infrastructure and where a comparatively short journey (as the ATR flies) might take many hours or even days by road or rail. Also between adjoining islands. Note the growth of Firefly out of PEN using ATRs, and the marked increase in scheduled short hops using small props around Indonesia and the Pacific.
TSS From United States of America, joined Dec 2006, 1604 posts, RR: 6 Reply 4, posted (5 months 1 week 5 days 20 hours ago) and read 15249 times:
Quoting Dash9 (Thread starter): What specs would a new, bigger turboprop need to succeed against an equivalent sized jet? Speed, fuel economy, comfort, range?
I'd say the priorities on a new turboprop would be as follows:
1. Fuel Economy- This is a turboprop's main advantage over a similarly-sized jet. Better fuel economy = greater advantage.
2. Speed- Any propellor-driven aircraft is perceived as "slow" by the general flying public, so anything that brings turboprops and jets closer to parity in speed over short segments is a good thing.
3. Comfort- I've flown on CRJs and I've flown on a Q400, and comfort-wise there was no comparison: The Q400 won hands-down. An ad showing passengers packed into "Airline B's" CRJs versus those same passengers relaxing in comfort in "Airline A's" turboprops shouldn't be that hard to market.
4. Range- Since turboprops are only competitive with jets on shorter segments, a continent-spanning range shouldn't be a huge consideration.
Quoting Dash9 (Thread starter): How likely it is that it could be based on an existing / planned frame such as the A320 or Cseries?
Highly unlikely. Fitting two jet engines under the wings of the aforementioned aircraft is enough of a headache as it is. Now try to imagine fitting two appropriately-sized propellors on those aircraft... it wouldn't work. That leaves you with only one other choice- four (or more) engines, and a redesigned wing upon which to mount them. The redesigned wing would probably be necessary to decrease or eliminate the current amount of sweep anyway, but then that leads to other problems, etc, etc... Much easier to design an aircraft to be a turboprop from the get-go.
Able to kill active threads stone dead with a single post!
ADent From United States of America, joined Dec 2006, 521 posts, RR: 0 Reply 5, posted (5 months 1 week 5 days 20 hours ago) and read 15145 times:
Sure - when jet fuels hits $8/gallon and the fuel efficiency of a prop makes a significant difference (at least 10%, bur probably more like 33%) in the price of a ticket.
Luv2cattlecall From United States of America, joined Sep 2007, 1578 posts, RR: 2 Reply 6, posted (5 months 1 week 5 days 19 hours ago) and read 15127 times:
Quoting TSS (Reply 4): 3. Comfort- I've flown on CRJs and I've flown on a Q400, and comfort-wise there was no comparison: The Q400 won hands-down. An ad showing passengers packed into "Airline B's" CRJs versus those same passengers relaxing in comfort in "Airline A's" turboprops shouldn't be that hard to market.
Couldn't agree more! It amazes me that search sites like Priceline and Hotwire still have an "avoid turboprops" option!
Aside from their Aviation X headset, I am no fan of Bose products, but I realize how highly the general public thinks of them - for example, 99% of the people I talk to are convinced that their noise-canceling headsets will eliminate crying babies, when in reality, they make them worse.
Bombardier should find a way to get Bose to make a tiny tweak to the ANC technology - which works wonders on the Q400 - and add the tagline "enhanced with Bose noise-cancellation technology" or something along those lines.
Does Nike tend to advertise with quips about their engineering and technology, or by dropping celebrity names? There's no use trying to convince most people that current generation turboprops are nothing like what they rode 10 years ago... so just drop some fancy names and watch the SLF pay up!
When you have to breaststroke to your connecting flight...it's a crash!
Keesje From Netherlands, joined Apr 2001, 10190 posts, RR: 52 Reply 7, posted (5 months 1 week 5 days 17 hours ago) and read 14961 times:
Quoting Dash9 (Thread starter): Speed, fuel economy, comfort, range? How likely it is that it could be based on an existing / planned frame such as the A320 or Cseries?
I think ATR is working on a -900, a 100 seat Turboprop too.
A few yrs back I sketched a A320 sized (~150 seat) aircraft powered by two 11.000 shp engines. PPRUNE members helped in finetuning. It's has 3-3, APU powered electric drive to reduce noise / fuel during push back/taxiing, DLC & enough belly room for feeder services. Most high density traffic routes in the 500 million person European market are < 600nm. A 737/ A320 is made for 3000nm.
Burkhard From Germany, joined Nov 2006, 1778 posts, RR: 0 Reply 8, posted (5 months 1 week 5 days 16 hours ago) and read 14896 times:
I think that technologically the turbofan and the turboprop get clother and clother, and somehow a mantelled open rotor may be the long time solution - isn't the GTF alread more a turbo prop than a jet?
MEA-707 From Netherlands, joined Nov 1999, 3462 posts, RR: 45 Reply 10, posted (5 months 1 week 5 days 16 hours ago) and read 14837 times:
Seeing that the biggest variants of the ATR's and DHC products are the most popular and they can't stretch them much further, it would be possible if they make a clean sheet 5 abreast fuselage design, which has potential to carry 65 to 150 pax.
A nice trip back on memory lane to the 1960s (Il-18, Viscount, Connie, Electra, DC-6/7) when the last 5 abreast propliners were built or in frontline service. (NB Vanguard and Britannia were 6 abreast)
nobody has ever died from hard work, but why take the risk?
RayChuang From United States of America, joined Jun 2000, 7141 posts, RR: 8 Reply 12, posted (5 months 1 week 5 days 13 hours ago) and read 14161 times:
If they can figure out a way to quiet down the 8-bladed propellers properly, Keejse's proposed Turboliner with its Mach 0.7 cruising speed would be perfect for under 1,000 nautical mile routes, especially if it can duplicate the 124-seat 32.8 inch seat pitch configuration used by Southwest Airlines. It would be perfect as a shorter-range replacement of the 737-300 on Southwest's routes on the intra-California and intra-Texas markets.
Dash9 From Canada, joined Nov 2008, 26 posts, RR: 0 Reply 15, posted (5 months 1 week 5 days 13 hours ago) and read 13673 times:
Quoting Keesje (Reply 7): A few yrs back I sketched a A320 sized (~150 seat) aircraft powered by two 11.000 shp engines.
Thanks Keesje that is exactly the kind of turboprop I had in mind!
Quoting Acelanzarote (Reply 11): Are not ATR making an ATR72-600, not sure on the details
but think its somehwat larger than the AT72-500?
nope, the -600 is only an improved -500, mostly on the avionic side.
Quoting TSS (Reply 4): Fitting two jet engines under the wings of the aforementioned aircraft is enough of a headache
Understand. How about a common fuselage like the Airbus A300/310/330/340, but a custom-made wing? I'm thinking Bombardier here, since they are developping the 5-abreast Cseries, couldn't the reuse the fuselage for the Q400X project?
Captaink From Mexico, joined May 2001, 4542 posts, RR: 16 Reply 16, posted (5 months 1 week 5 days 12 hours ago) and read 13587 times:
Quoting PWMRamper (Reply 9):
Because I think the Q4's are MUCH quieter than any RJ.
THe Q400 is supposedly quite quiet. But not all RJs are loud either. I find the ERJ rather quiet on full thrust , save for the wind noise. Personally I find ERJs the perfect short flight aircraft.
Keesje From Netherlands, joined Apr 2001, 10190 posts, RR: 52 Reply 17, posted (5 months 1 week 5 days 12 hours ago) and read 13549 times:
I think the props have become more quiet. The engine I took for the Turboliner is at this moment the only modern one available > 10.000 shp (the An70 props engine seem not very quiet)
As we speak R&D (GE, RR, Airbus,Boeing) is focussing on Counter Rotating Rotors that promise an additional 5% energy effiency on top of conventional props. http://www.nlr.nl/eCache/DEF/12/623.jpg
Keesje From Netherlands, joined Apr 2001, 10190 posts, RR: 52 Reply 20, posted (5 months 1 week 5 days 11 hours ago) and read 12714 times:
Quoting BrusselsSouth (Reply 14): Actually, there's already been a large turboprop airliner : the Tupolev Tu-114.
Although very advanced, half Siberia was left with Noise induced hearing loss because of it. Its fifties technology. The worlds largest transport for some time, the Anteus, had them too.
AM744 From Mexico, joined Jun 2001, 1312 posts, RR: 0 Reply 21, posted (5 months 1 week 5 days 10 hours ago) and read 12050 times:
Quoting TSS (Reply 4): 2. Speed- Any propellor-driven aircraft is perceived as "slow" by the general flying public, so anything that brings turboprops and jets closer to parity in speed over short segments is a good thing.
Didn't the SAAB 2000 tried that one? I'm not privy on the complete story. Perhaps a better timing could help a large and fast turboprop.
Keesje From Netherlands, joined Apr 2001, 10190 posts, RR: 52 Reply 23, posted (5 months 1 week 5 days 10 hours ago) and read 11782 times:
Quoting AM744 (Reply 21): Quoting TSS (Reply 4):
2. Speed- Any propellor-driven aircraft is perceived as "slow" by the general flying public, so anything that brings turboprops and jets closer to parity in speed over short segments is a good thing.
Didn't the SAAB 2000 tried that one? I'm not privy on the complete story. Perhaps a better timing could help a large and fast turboprop.
Passenger perception is hard to stear but I think economies could do a lot. With the dense markets of Europe but also markets like RayChuang identified the flight times are so short the additional 5-15 minutes flight times are minor in the total travel time.
Aircraft like 737's and A320's are much more capable, expensive and heavy. That was acceptable when fuel was cheap, speed was king and no big props existed.
Voodoo From Niue, joined Mar 2001, 1864 posts, RR: 0 Reply 24, posted (5 months 1 week 5 days 10 hours ago) and read 11758 times:
Just tried to look for a drawing/mock-up images of the A340 IAE Superfan combo design from the '80s. Can't seem to find any with the obvious keywords. Its as if IAE/Airbus have been going through with a fine tooth comb to delete them?
UALWN From Spain, joined Jun 2009, 470 posts, RR: 1 Reply 25, posted (5 months 1 week 5 days 10 hours ago) and read 11734 times:
Quoting AM744 (Reply 21): Didn't the SAAB 2000 tried that one? I'm not privy on the complete story. Perhaps a better timing could help a large and fast turboprop.
In the 90s Crossair called their SAABs 2000 "Concordino", as they called their RJ85s "Jumbollino".
Saab2000 From Switzerland, joined Jun 2001, 1346 posts, RR: 10 Reply 26, posted (5 months 1 week 5 days 9 hours ago) and read 12347 times:
Quoting AM744 (Reply 21): Didn't the SAAB 2000 tried that one? I'm not privy on the complete story. Perhaps a better timing could help a large and fast turboprop.
I flew SAAB2000s for Crossair/SWISS for a few years and they were indeed nice airplanes.
Now I fly the CRJ-200 and honestly, there's little comparison in speed over longer routes. The CRJ has a climb speed faster than the cruise of the SAAB2000. Still, we cruised at about 360 KTAS in the SB-20 and about 460 KTAS in the CRJ. Or .64 Mach in the SB-20 and .74+ in the CRJ.
On short, east coast hops like I normally do the SB-20 would have little disadvantage in terms of absolute speed, but when ATC wants 'Max Forward Speed, you're leading the pack', the SB-20's max indicated of about 270-280 won't cut it. Yesterday we gave them 330 KIAS for a long time on the way into PHL. And on longer routes we do the CRJ has a distinct speed advantage. Some of the routes, like BOS-IND or LGA-SDF or PHL-MCI are simply not really appropriate for today's turboprop technology. But a version like Keesje's design would be awesome.
I'd love the see a modern turboprop in a large, wider-body style. The SB-20 was based on the fuselage diameter of the SAAB340 and thus was a bit narrow and claustrophobic.
The public distaste for turboprops could be eliminated with good marketing and an exceptional product with legitimately lower costs.
GST From United Kingdom, joined Jun 2008, 463 posts, RR: 0 Reply 27, posted (5 months 1 week 5 days 9 hours ago) and read 12284 times:
Quoting Dash9 (Reply 15): Understand. How about a common fuselage like the Airbus A300/310/330/340, but a custom-made wing? I'm thinking Bombardier here, since they are developping the 5-abreast Cseries, couldn't the reuse the fuselage for the Q400X project?
The trouble is that Turboprops usually operate shorter segments, and therefore cruise at lower altitudes with higher external air pressures as the norm. Taking a stock turbofan aircraft fuselage will only hinder this really, as you will have a skin that is optomised to be carrying extra pressure loadings, in addition to the higher cruise mach of the turbofan fuselage. This means extra weight in the excess skin thickness and supporting structure due to these. There will also be an element of the fuselage performing better aerodynamically at the higher mach, as that would be its primary design point. You may therefore need to redesign the nose and tailcone profiles to get an optomised profile for the lower speed. I think you will be better getting either a stretched prop plane's fuselage, or scrath designing one if you want to maintain as much of the efficiency benefits the engines give you.
Quoting Captaink (Reply 16):
THe Q400 is supposedly quite quiet. But not all RJs are loud either. I find the ERJ rather quiet on full thrust , save for the wind noise. Personally I find ERJs the perfect short flight aircraft.
I live very close to the flight path of Belfast City Airport, and all day hear Q400s, Embraer 195s, A320s, and 737s flying in and out. The Q400 is by a huge way the quietest sofar as I can gauge.
Gliding is to power flying as seduction is to rape.
LongHauler From Canada, joined Mar 2004, 1937 posts, RR: 20 Reply 28, posted (5 months 1 week 5 days 9 hours ago) and read 12103 times:
Old habits are hard to overcome ... other than the usual readers on here.
A friend of mine recently said she "flew on an old propeller plane to Halifax." I doubted her until she said it was a cheap flight on Porter Airlines. Obviously a Q400.
Her final words were "next time I will play extra to fly on a jet!".
I tried to explain that the Q400 is every bit as advanced as most jets flying, but that was falling on deaf ears. And this lady is not uneducated nor unworldly, she is the Editor of one of the large magazines published in Toronto!
Public perception!
On average, more people are killed yearly by falling coconuts (150), than by sharks (10).
Keesje From Netherlands, joined Apr 2001, 10190 posts, RR: 52 Reply 29, posted (5 months 1 week 5 days 9 hours ago) and read 12153 times:
Quoting LongHauler (Reply 28): Her final words were "next time I will play extra to fly on a jet!".
Current RJ's (props) are also unpopular because of small cabins, very limitted carry luggage and noise.
I think wider seats, light (roof top windows) a nicely curved cabin, large bins, introduction pricing and a consistent "sparing the environment campaign" could do a lot..
In the end schedule, price and FF programs are the main drivers..
Rampart From United States of America, joined Aug 2005, 1755 posts, RR: 11 Reply 30, posted (5 months 1 week 5 days 8 hours ago) and read 11618 times:
Quoting Saab2000 (Reply 26): On short, east coast hops like I normally do the SB-20 would have little disadvantage in terms of absolute speed, but when ATC wants 'Max Forward Speed, you're leading the pack', the SB-20's max indicated of about 270-280 won't cut it. Yesterday we gave them 330 KIAS for a long time on the way into PHL. And on longer routes we do the CRJ has a distinct speed advantage. Some of the routes, like BOS-IND or LGA-SDF or PHL-MCI are simply not really appropriate for today's turboprop technology.
That, I'm afraid, is the Achilles heel for this concept, much as I'd like to see a revival of sensible turboprops. If regional jets are said to be a burden on that air traffic flow at the major airports (don't know if that's true except for numbers of them that might be more rational with consolidated larger capacity), large turboprops would slow the net flow for everyone. What would be the solutions? Dedicated turboprop altitudes or lanes?
Manfredj From United States of America, joined Mar 2007, 913 posts, RR: 0 Reply 31, posted (5 months 1 week 5 days 8 hours ago) and read 11262 times:
I think this is an interesting thread. I'll chime in with my favorite, which has already been mentioned. I think SAAB has(d) some of the best products out there. The 2000, had it been marketed correctly, would have been a great success in the US. Unfortunately its life was primarily limited to the European market.
From what I've heard it's a wonderful, comfortable aircraft to fly and be flown in. The CRJ/ERJ/SAAB 2000 have very close perfomance figures when all is said and done.
Only problem is, we have made another one of those decisions (mentally) that a like sized turbojet is the superior choice. The truth of the matter is, made correctly, the turboprop would make a fine large transporter. SAAB proved this in many ways with the 2000. Again, had this aircraft been marketed correctly, it could have led to much more interesting projects.
Fanofjets From United States of America, joined Apr 2000, 1736 posts, RR: 4 Reply 32, posted (5 months 1 week 5 days 8 hours ago) and read 11236 times:
Quoting OtnySASLHR (Reply 18): think that the Saunders Roe might have been bigger:-
Nice picture of the SARO Princess! There is also some great footage of that aircraft on YouTube. Saunders-Roe had an even larger turbojet-powered version of the graceful Princess on the drawing board:
The "newest" proposed large passenger turboprop I could find was this design by Lockheed from the late 1970s; I took the picture from a 1980 book and added the color:
IMissPiedmont From United States of America, joined May 2001, 5621 posts, RR: 52 Reply 33, posted (5 months 1 week 5 days 8 hours ago) and read 11152 times:
Quoting BrusselsSouth (Reply 14): Actually, there's already been a large turboprop airliner : the Tupolev Tu-114.
It was indeed noisy but there is yet to be an aircraft made that is more fun to watch.
Though my eyes could see I still was a blind man, though my mind could think I still was a madman
Rampart From United States of America, joined Aug 2005, 1755 posts, RR: 11 Reply 34, posted (5 months 1 week 5 days 7 hours ago) and read 10517 times:
Quoting Fanofjets (Reply 32):
(There are more "paper airplanes in my Webshots album, which I will soon expand and transfer to Flickr.)
dlberek, aka fanofjets
Great collection of "paper airplanes"! I've had you "bookmarked" for some time now, and now I know you on A.net. I've always loved the Republic Rainbow. What an elegant craft.
Off topic, but if you ever find any pictures of early DH Comet concepts, let us know. There were some weird Comet concepts out there, but I can only vaguely recall from aviation magazines 30 years ago.
THe Q400 is supposedly quite quiet. But not all RJs are loud either. I find the ERJ rather quiet on full thrust , save for the wind noise. Personally I find ERJs the perfect short flight aircraft.
I live very close to the flight path of Belfast City Airport, and all day hear Q400s, Embraer 195s, A320s, and 737s flying in and out. The Q400 is by a huge way the quietest sofar as I can gauge.
Quiet inside the passenger cabin and quiet on the ground under the flight-path are two entirely different things. The back of a Q400 isn't bad, but the direct noise plus vibration induced noise is very tiring anywhere in the vicinity of the prop's.
N1120A From United States of America, joined Dec 2003, 24124 posts, RR: 86 Reply 38, posted (5 months 1 week 5 days 6 hours ago) and read 9519 times:
Quoting Keesje (Reply 7): A 737/ A320 is made for 3000nm
Not really. That they don't really have that capability in real life is added to by the fact that they were engineered for short as well as medium haul. While a fast prop would be better up to about 1000nm, those two are still competitive on shorter routes.
Quoting PWMRamper (Reply 9):
Quoting Thegeek (Reply 1):
Turboprops, even the Q400 are much nosier than jets
Are you including the Q400 in that statement?
Because I think the Q4's are MUCH quieter than any RJ.
How many jets actively include noise and vibration reducing technology, in addition to the rest of the engineering? The Q400 is one of the quietest aircraft out there to fly.
Quoting BrusselsSouth (Reply 14): Actually, there's already been a large turboprop airliner : the Tupolev Tu-114.
Ah the Bear. I was going to mention her. Extremely fast too.
Quoting AM744 (Reply 21): Didn't the SAAB 2000 tried that one? I'm not privy on the complete story. Perhaps a better timing could help a large and fast turboprop.
The 2000's biggest problem was its early introduction. She was launched at the height of RJ mania and before the collapse of the world economy under the weight of high oil prices. The other thing is that the 2000s is both smaller and more thirsty than the Q400.
GST From United Kingdom, joined Jun 2008, 463 posts, RR: 0 Reply 39, posted (5 months 1 week 5 days 6 hours ago) and read 9492 times:
Quoting Robsaw (Reply 37): Quiet inside the passenger cabin and quiet on the ground under the flight-path are two entirely different things. The back of a Q400 isn't bad, but the direct noise plus vibration induced noise is very tiring anywhere in the vicinity of the prop's.
I also fly Q400 very regularly between Belfast City and Manchester, and do not think that next to the props is any more uncomfortable than near the engines on a CRJ or such, Personally taking an "average" internal and external noise the Q400 would work out quiter than or equal to just about all others.
Quoting N1120A (Reply 38): Given what happened with the Comet, I would be wary of any aircraft with a different window design.
How exactly is adding a row of coonventional windows along the roof that much different to adding them along the sides? It is unlikely that they would make some far out innovation in rooftop windows, they dont need to be big to let in light.
[Edited 2009-08-31 12:41:14]
Gliding is to power flying as seduction is to rape.
FlyDeltaJets87 From United States of America, joined Aug 2006, 4824 posts, RR: 38 Reply 41, posted (5 months 1 week 5 days 5 hours ago) and read 9054 times:
Given what happened with the Comet, I would be wary of any aircraft with a different window design.
Quoting GST (Reply 39): How exactly is adding a row of coonventional windows along the roof that much different to adding them along the sides? It is unlikely that they would make some far out innovation in rooftop windows, they dont need to be big to let in light.
It shouldn't have much of an impact, so long as the rest of the fuselage is properly strengthened. The Comet had problems because they used windows with square edges instead of rounded ones. The idea of using square windows on planes was so that they wouldn't resemble portholes on ships. This was fine when aircraft weren't pressurized. But Square edges are stress concentration points and the constant pressurization and depressurization weakened the metal (metal fatigue) and thus the results with the Comets. Rounded windows allow the shear flow to do just that "Flow" without concentrating at any one point.
Timz From United States of America, joined Sep 1999, 5458 posts, RR: 6 Reply 42, posted (5 months 1 week 5 days 5 hours ago) and read 8488 times:
The only point of the turboprop would be to burn less fuel per seat, right? No other advantage, for anyone?
So how much fuel would it save on a given trip? Nobody here seems to know. Does anyone even know how much fuel a Vanguard would save compared to a 737/A320? If any?
Viscount724 From Switzerland, joined Oct 2006, 11635 posts, RR: 13 Reply 44, posted (5 months 1 week 5 days 4 hours ago) and read 8185 times:
Quoting MEA-707 (Reply 10): (NB Vanguard and Britannia were 6 abreast)
However the majority of Vanguards built, the 23 operated by AC, had much more spacious 5-abreast seating in Y class. BEA's (the only other customer) were 6-abreast.
Quoting GhYHZ (Reply 22): Loftleiðir Icelandic Airlines operated a stretched version of this, the CL-44J which had 189 seats.
For a while, their CL-44Js were the largest aircraft in service on transatlantic routes.
Saab2000 From Switzerland, joined Jun 2001, 1346 posts, RR: 10 Reply 45, posted (5 months 1 week 5 days 4 hours ago) and read 8015 times:
Quoting Timz (Reply 42): The only point of the turboprop would be to burn less fuel per seat, right? No other advantage, for anyone?
Vastly better runway performance is another huge advantage. The CRJ-200 uses a lot of runway when heavy.
We can use RWY 8 in PHL when somewhat light in an easterly operation if we have dry runways. As soon as the runway is wet forget it. A turboprop would rarely be restricted in such cases.
A 100+ passenger turboprop would probably be viable in and out of runways most jets (excluding Avro/BAe-146 variants) simply cannot do. LCY is the obvious example in Europe and Aspen, Colorado is the clear US example.
GST From United Kingdom, joined Jun 2008, 463 posts, RR: 0 Reply 46, posted (5 months 1 week 5 days 4 hours ago) and read 7792 times:
Quoting Timz (Reply 42): So how much fuel would it save on a given trip? Nobody here seems to know.
Surely you realise without very specific information on loadings, aircraft profiles, engine types, speeds used etc etc it is impossible to quantify this.
Gliding is to power flying as seduction is to rape.
Prebennorholm From Denmark, joined Mar 2000, 5192 posts, RR: 55 Reply 48, posted (5 months 1 week 5 days 2 hours ago) and read 6596 times:
One problem with turboprop planes is that they don't go so high. At least they will have very limited climb capability at high altitude.
The whole idea of turboprop advantages is that the propeller tips are kept at subsonic speed. It puts an effective ceiling on thrust in the thin air at FL300 or higher.
The Tu-114 did it. But if I'm not mistaken, then at least during climb and fast flight at altitude its propeller tips went supersonic. And that was the main reason why it was the absolutely most noisy airliner this world has ever seen, both external and internal noise.
Turboprops are best when allowed to fly at FL250 or lower. It will create a terrible ATC headache in most of Europe and North America if a significant part of 737/320 replacements would be limited to such low altitudes.
On the other hand, I would like to see real expert judgements of how much fuel efficiency could be gained on a modern 150 seat turboprop flying 500nm or more at FL250 compared to a 737 or 320 flying at FL350.
Modern turbofan planes win enormously in economy because they can cruise pretty fast up there where the air is thin and drag is low at high speed. And they can get up there pretty fast. Turboprop planes will at least have to struggle for much longer time to get up there.
In cruise the engines are there to overcome drag. Drag is very much the same 5.5 to 6% of the weight of the plane whether it is cruising at Mach 0.8 at FL350 or Mach 0.6 at FL250. But in the later case you will spend more time and energy overcoming that drag.
Therefore the turboprop has to be a lot more efficient to overcome that extra drag and still come out as a total winner on flights where most of the time is spent in level cruise at optimal altitude.
I'm not so sure that the turboprop really will come out favorably at longer ranges. But I am sure that if they become many, then they will cramp the lower flight levels to an unbearable degree.
But one thing is sure: Turboprops have a fantastic thrust at sea level. Nothing can compete with that. Therefore they are the obvious choise when runways are short.
Always keep your number of landings equal to your number of take-offs, Preben Norholm
Dw747400 From United States of America, joined Aug 2001, 1025 posts, RR: 1 Reply 50, posted (5 months 1 week 5 days ago) and read 5538 times:
Quoting Prebennorholm (Reply 48): One problem with turboprop planes is that they don't go so high.
The problem with cruise altitude probably won't be that big of an issue on short flights. For example, with a reasonably full payload (150 pax and 5000 pounds of cargo) a 757-200, a very good climber, still has an optimum flight level of FL190-FL280 on flights under 250nm. Even on 500nm flights, where the aircraft could see a slight benefit in the high 30's, ATC frequently keeps aircraft lower.
The space between 10,000 feet and FL250 is often the least congested, at least in the US. Of course, it still has its problems--more weather, conflicts between low altitude enroute traffic and high altitude traffic approaching terminal airports, etc.
Turboprops also have the unique ability to operate with (relative) efficiency at low altitudes. In some cases, particularly in the northeast, the ability to fly below 12,000 feet can reduce delays significantly. This is horribly inefficient for a 737, but a next-gen turboprop might be able to pull it off.
That said, I do agree that altitude limits cause one problem for turboprops: limited flexibility. Whereas a 737 can fly IAD to PHL and then go on to DEN, such a trip would put a turboprop out of its element. Not only would the low speeds increase leg times, but lines of storms, turbulence, and other issues would be a real pain at FL250.
Kappel From Suriname, joined Jul 2005, 3003 posts, RR: 8 Reply 52, posted (5 months 1 week 4 days 14 hours ago) and read 4761 times:
Quoting Robsaw (Reply 37): Quiet inside the passenger cabin and quiet on the ground under the flight-path are two entirely different things. The back of a Q400 isn't bad, but the direct noise plus vibration induced noise is very tiring anywhere in the vicinity of the prop's.
Indeed, and the same can be said about CRJ's. Sitting in the back next to an engine, or in the front of a CRJ700/900 makes a HUGE difference (same as all jets with tail mounted engines).
Sphealey From United States of America, joined May 2005, 297 posts, RR: 0 Reply 53, posted (5 months 1 week 4 days 14 hours ago) and read 4651 times:
The word "ever" (and its counterpart "never") has to be balanced against the price of oil and competing liquid fuels. Should - or perhaps when - oil reaches back up to and past $200/bbl there will be many things done/tradeoffs made that seem unlikely or undesirable today.
Keesje From Netherlands, joined Apr 2001, 10190 posts, RR: 52 Reply 54, posted (5 months 1 week 4 days 13 hours ago) and read 4657 times:
Quoting Thegeek (Reply 51): Perhaps I've been unlucky and sat near the prop
Props tend to make noise that can be tiring. I think the short trips, where props can be effective, are full of action / disturbances anyway. So I tend to believe a higher noise level is acceptable then on medium / long haul flights. How exhausted can you get in an hour..
Seeing the R&D that seems to go on on counter rotating open rotors I wouldn't be surprized if a next generation of turbo props has those. They promise a 5% better energy eficiency
(Ref. http://www.nlr.nl/smartsite.dws?id=12618) and reduced torque.
Rolls-Royce expressed confidence this week that the open rotor concept can be viable, asserting that it will "comfortably meet Stage 4 noise requirements." Speaking in Washington at the Eco-Aviation conference presented by ATW and Leeham Co., Strategic Marketing Manager-Future Programs Paul Randall said the open rotor is "the true game-changer" and could provide a 25%-30% fuel efficiency gain over turbofans powering narrowbodies today and be 10%-15% more fuel efficient than advanced turbofans that may come on line in the next decade.
Captaink From Mexico, joined May 2001, 4542 posts, RR: 16 Reply 55, posted (5 months 1 week 4 days 13 hours ago) and read 4554 times:
Quoting GST (Reply 27):
I live very close to the flight path of Belfast City Airport, and all day hear Q400s, Embraer 195s, A320s, and 737s flying in and out. The Q400 is by a huge way the quietest sofar as I can gauge.
I don't doubt that, but I was referring more to the passenger's perspective. With the RJ's engines usually way at the back you get the DC9 effect, that is you hear very little unless you are in the washroom.
By the way, there is an area I can think of that Props beat jets any day, and that is in the Caribbean. Jets have been tried, but to fly 100nm flights all day, nothing beats the Dash 8, which has proven over the years to be the airplane of choice.
I used to work for a company that handled Caribbean Star, and in the morning we would have a flight, #792, that does POS/GND/SVD/SLU/DOM/ANU/SKB/SXM/BVI, can you imagine an ERJ or a CRJ doing that? The longest of those flights is about 30min on a prop.
EMB170 From United States of America, joined Nov 2007, 480 posts, RR: 0 Reply 56, posted (5 months 1 week 4 days 13 hours ago) and read 4561 times:
Keesje, it's a nice drawing...I have one question, though. If you're designing a propliner in the 140-160 seat range category, the FAA/JAA would probably mandate that you have mid-cabin emergency exits underwing (at least 2 and possibly 4). Would that be possible with the props outside the window or would that be too dangerous?
Can passenger jets fly as fast as my feet do? Let's find out...
9252fly From Canada, joined Sep 2005, 906 posts, RR: 0 Reply 57, posted (5 months 1 week 4 days 10 hours ago) and read 4377 times:
What are the chances of Bombardier going ahead with a DH4 stretch,is it a plug too much? Would the maximum seating capacity be 90 seats? Seems the economics would be good based on CASM. Perhaps 100 seats would be the largest we will see a new generation of turbo-props designed to. Is there demand for a turbo-prop with that capacity today,it's something Bombardier could build but what's the point if no one orders it.
AM744 From Mexico, joined Jun 2001, 1312 posts, RR: 0 Reply 58, posted (5 months 1 week 4 days 8 hours ago) and read 4253 times:
Quoting LongHauler (Reply 28): Old habits are hard to overcome ... other than the usual readers on here.
A friend of mine recently said she "flew on an old propeller plane to Halifax." I doubted her until she said it was a cheap flight on Porter Airlines. Obviously a Q400.
Her final words were "next time I will play extra to fly on a jet!".
I tried to explain that the Q400 is every bit as advanced as most jets flying, but that was falling on deaf ears. And this lady is not uneducated nor unworldly, she is the Editor of one of the large magazines published in Toronto!
Public perception!
A previous job required frequent travel to Manzanillo (ZLO) and my coworkers disliked Aeromar's (VW) ATR-42 for the mere fact of being a turboprop, so lots of propaganda is in order if the concept is ever to take off.
TSS From United States of America, joined Dec 2006, 1604 posts, RR: 6 Reply 59, posted (5 months 1 week 4 days 8 hours ago) and read 4253 times:
Quoting Thegeek (Reply 51): When I've been on a Q400 it seemed noisier than a jet. Perhaps I've been unlucky and sat near the prop. I suppose a 717 is noisy near the engines too.
Quoting EMB170 (Reply 56): Keesje, it's a nice drawing...I have one question, though. If you're designing a propliner in the 140-160 seat range category, the FAA/JAA would probably mandate that you have mid-cabin emergency exits underwing (at least 2 and possibly 4). Would that be possible with the props outside the window or would that be too dangerous?
Why not kill two birds with one stone and have the lavatories installed just ahead of the mid-cabin point and in line with the props, thereby eliminating seats in the loudest area of the cabin? Then fit the required emergency exits just behind the lavs and directly under the wings.
Able to kill active threads stone dead with a single post!
FlyDeltaJets87 From United States of America, joined Aug 2006, 4824 posts, RR: 38 Reply 60, posted (5 months 1 week 4 days 8 hours ago) and read 4223 times:
Quoting EMB170 (Reply 56): Keesje, it's a nice drawing...I have one question, though. If you're designing a propliner in the 140-160 seat range category, the FAA/JAA would probably mandate that you have mid-cabin emergency exits underwing (at least 2 and possibly 4). Would that be possible with the props outside the window or would that be too dangerous?
There are mid cabin emergency exits under the wing in Reply 7. The safety demo and safety card would need to clearly show the escape route being away (aft) from the props.
GST From United Kingdom, joined Jun 2008, 463 posts, RR: 0 Reply 61, posted (5 months 1 week 4 days 7 hours ago) and read 4149 times:
Quoting Captaink (Reply 55): I don't doubt that, but I was referring more to the passenger's perspective. With the RJ's engines usually way at the back you get the DC9 effect, that is you hear very little unless you are in the washroom. Big grin
Not my experience with numerous Q400 flights, but having said that I havent ridden a DC9 so cant comment on that comparison.
Quoting EMB170 (Reply 56): Keesje, it's a nice drawing...I have one question, though. If you're designing a propliner in the 140-160 seat range category, the FAA/JAA would probably mandate that you have mid-cabin emergency exits underwing (at least 2 and possibly 4). Would that be possible with the props outside the window or would that be too dangerous?
I remember flying on the Jetstream 31 and seeing that it has overwing exits behind the props, and from what I dee, mid fuselage emergency exits are not uncommon among props, even if this example is a dinky one in comparison to the hypothetical large prop. It is also worth noting that in the event of the emergency exits needing to be used, either A) the aircraft is largely intact and flight crew would have been able to kill the power, and by the time pax are unstrapped, doors open and clambering out, the props may not be spinning fast if at all. Otherwise B) following an undercarriage collapse/more serious incident, it is likely that a prop strike with the ground will have occured and the spinny wheels of death stopped forcefully.
Quoting AM744 (Reply 58):
A previous job required frequent travel to Manzanillo (ZLO) and my coworkers disliked Aeromar's (VW) ATR-42 for the mere fact of being a turboprop, so lots of propaganda is in order if the concept is ever to take off.
Basically we need the exact opposite of the marketing airlines did in the 1950s/60s trying to persuade the public that jets were indeed safe, and getting people away from the "in prop we trust" mood, and that no, just because you couldnt see what pushed the plane forewards, it was no less real with a jet than a propeller.
Gliding is to power flying as seduction is to rape.
Brilondon From Canada, joined Aug 2005, 1560 posts, RR: 0 Reply 62, posted (5 months 1 week 4 days 7 hours ago) and read 4068 times:
Quoting 9252fly (Reply 57): What are the chances of Bombardier going ahead with a DH4 stretch,is it a plug too much? Would the maximum seating capacity be 90 seats? Seems the economics would be good based on CASM. Perhaps 100 seats would be the largest we will see a new generation of turbo-props designed to. Is there demand for a turbo-prop with that capacity today,it's something Bombardier could build but what's the point if no one orders it.
I'm no engineer, but I would think that maybe there may be an issue with the wing and economies of scale. You could only get so big and then you start getting into structural issues around the wing and performance issues. The original intention of the Dash 8 was to be able to operate into smaller airports. Once you get so big you end up losing the primary focus of the aircraft and its purpose. These are just my thoughts not facts so cut me up all you like if I am wrong in my assessment of the situation.
GST From United Kingdom, joined Jun 2008, 463 posts, RR: 0 Reply 63, posted (5 months 1 week 4 days 6 hours ago) and read 4036 times:
Quoting Brilondon (Reply 62):
I'm no engineer, but I would think that maybe there may be an issue with the wing and economies of scale. You could only get so big and then you start getting into structural issues around the wing and performance issues. The original intention of the Dash 8 was to be able to operate into smaller airports. Once you get so big you end up losing the primary focus of the aircraft and its purpose. These are just my thoughts not facts so cut me up all you like if I am wrong in my assessment of the situation.
You are not wrong in that assessment generally. It is worth noting though that the Dash 8 is an old design, but that its wing in various guises has been sucessfully used on numerous design iterations of the aircraft. I do not know if it has had any improvement to its aerofoil or its profile over the different Dash aircraft (I put that question to a Bombardier engineer at their Belfast plant, but he either diddnt know or couldnt say, although Belfast builds Q400 fuselages but I dont think does anything with the wings). I do think that given that the current wing is a 10 year old design at the very least, that small improvements can and will deffinately be made to make a new stretch work competitavely on the market, with relatively little work needing to be done to reoptomise the structure etc.
Gliding is to power flying as seduction is to rape.
R2rho From Germany, joined Feb 2007, 961 posts, RR: 1 Reply 64, posted (5 months 1 week 4 days 4 hours ago) and read 3946 times:
Oil will tell....
In any case, we are seeing a first step in this direction with the proposed Q400X stretch and the all-new 70-90 seat a/c that ATR is planning.
As for a 100+ seater, likely 5 or 6 abreast prop, it will have to wait. But oil is already back at 75$ and will come back to its "natural" level of 100$ soon enough, bringing attention back to turboprops.
Props don't necessarily have to be slow - the Tu-95 / 114 already proved that decades ago. Sure it's noisy, but it's 1950's technology, I wonder what we would be capable of today.... Even the A400M will be able to cruise at M 0.70 - not bad for a Western prop.
M 0.70 is not that much slower than the 0.78 of the A320 and 737, and on your average short-haul flight you won't notice the difference.
Of course, that potential future airplane may not be a prop in the classical sense. It could have counter-rotating props, or propfans like the An-70. But even a fast classic prop could do the job well enough on short sectors. I certainly think that, with every $ that oil increases, the incentive to build such an airplane does so too.
Prebennorholm From Denmark, joined Mar 2000, 5192 posts, RR: 55 Reply 65, posted (5 months 1 week 4 days 3 hours ago) and read 3906 times:
Quoting R2rho (Reply 64): Props don't necessarily have to be slow - the Tu-95 / 114 already proved that decades ago. Sure it's noisy, but it's 1950's technology, I wonder what we would be capable of today....
The Tu-114 was pretty fast because it had supersonic propeller tips.
The Tu-114 was very noisy because it had supersonic propeller tips.
There are some natural laws which are hard to bend.
Quoting R2rho (Reply 64): Even the A400M will be able to cruise at M 0.70 - not bad for a Western prop.
Is M=0.70 for A400M max cruise or economic cruise speed? I don't know, but I doubt that it is economic cruise. We should compare economic cruise speeds.
But even if we settle for M=0.55 to 0.60, then is shouldn't be a show stopper. If there is a significant economic gain, then some of that money could be used on speeding up check-in queues, security queues, and sometimes also baggage reclaim. And even 1500nm flights could often be faster than today.
Always keep your number of landings equal to your number of take-offs, Preben Norholm
R2rho From Germany, joined Feb 2007, 961 posts, RR: 1 Reply 66, posted (5 months 1 week 3 days 16 hours ago) and read 3687 times:
Quoting Prebennorholm (Reply 65): The Tu-114 was pretty fast because it had supersonic propeller tips.
The Tu-114 was very noisy because it had supersonic propeller tips.
There are some natural laws which are hard to bend.
Sure, but look at those old propellers. They're pretty conventional. Surely, a modern advanced scimitar bladed prop (which delays supersonic entry of the tips, thereby allowing for faster turning props without going supersonic) could do better - that is, for a similar speed, much less noise.
Furthermore, AFAIK the Tu's prop tips only go supersonic at max speed or at high-altitude max cruise speed. Otherwise they're subsonic (correct me if I'm wrong though).
For reference, the A400M props turn at 842rpm max, and have a tip speed of 290 m/s at M 0.68. I think the Tu-95 turns around 750-800rpm.
Quoting Prebennorholm (Reply 65): Is M=0.70 for A400M max cruise or economic cruise speed? I don't know, but I doubt that it is economic cruise. We should compare economic cruise speeds.
Hard to say. airbusmilitary.com states "cruise speed range" from 0.68-0.72, whatever that means. But their typical ferry mission shows a speed of around 400knots.
R2rho From Germany, joined Feb 2007, 961 posts, RR: 1 Reply 68, posted (5 months 1 week 3 days 5 hours ago) and read 3372 times:
Quoting Timz (Reply 67): Because it turns fewer revs/minute, you mean? Or because it's smaller?
Sorry if the numbers I put up were confusing, I was trying to say that at what seems to be a similar rotation speed of 800rpm, the Tupolev props tend to go supersonic, while the A400M's more advanced props don't.
I've forgotten a lot of my aerodynamics, but IIRC the scimitar blades make the tip "see" a lower Mach number than if the prop were straight, which delays the formation of a shock wave. Basically the same principle as with swept wings, except those are easier to design because the velocity vector is only in one direction. With props you have a rotational velocity component plus a forward velocity, hence the complex shape that results.
Prebennorholm From Denmark, joined Mar 2000, 5192 posts, RR: 55 Reply 70, posted (5 months 1 week 3 days 2 hours ago) and read 3293 times:
Quoting R2rho (Reply 66): Sure, but look at those old propellers. They're pretty conventional. Surely, a modern advanced scimitar bladed prop (which delays supersonic entry of the tips, thereby allowing for faster turning props without going supersonic) could do better - that is, for a similar speed, much less noise.
Absolutely correct, dear R2rho. Scimitar shaped blades are the way to go to get the most speed out of prop planes.
Quoting R2rho (Reply 66): For reference, the A400M props turn at 842rpm max, and have a tip speed of 290 m/s at M 0.68.
Quoting R2rho (Reply 66): airbusmilitary.com states "cruise speed range" from 0.68-0.72, whatever that means. But their typical ferry mission shows a speed of around 400knots.
Now I tried to convert 400knots into Mach number, Assuming M=1 is 1100 km/h at FL250, then forward speed of the plane = Mach 0.67.
You tell us that 842rpm = tip speed 290 m/s = Mach0.68 - which I haven't checked, but it seems to be very good figures, which I have every reason to trust. But that speed is the propeller tip within the propeller disk.
Now we have the data to calculate the true airspeed of the propeller tip. Let us for simplicity assume that plane speed and rotational speed of the propeller tips are both M=0.675. Then when combining the two speeds we get the the true airspeed of the tips.
In this very slightly simplified calculation we simply multuply M=0.675 by the square root of two. The result is M=0.955. To that we can add a few percent of accelleration of the air on the front side of the propeller blade, and we can see that we are at the very limit when we want to avoid sound barrier bangs from the propellers.
From this data we can also read that when the A400M can cruise at M=0.72 without supersonic propellerl tips, then it has to be with a tip pitch somewhat more than 45 degrees, and it has to be with rpm slightly lower than the maximum 842 rpm.
This also tells us that M=0.72 is a fantastic achiement and the absolute cruise speed limit of any tuboprop plane when avoiding supersonic propeller noise.
Quoting Viscount724 (Reply 69): The Tu-114's unusual (for a turboprop) swept wings were a significant factor in its high speed.
That is very correct, dear Viscount. An additional reason for the rather high sweep back on the Tu-114 is also the unusual wing airfoil section. For simplicity is has no leading edge slats or any other leading edge high lift devices. But the wing airfoil section is shaped almost like "fixed slats", which of course improves low speed performance (takeoff and landing).
But that airfoil section is horrible compared to modern airliners when it comes to high subsonic Mach numbers. It was compensated by excessive sweep back related to actual speed performance.
The US cousin to the Tu-114 / Tu-95 is the B-52. It also has no leading edge devices, while it has a "normal" wing airfoil section which is suitable for high subsonic speed. It compensates for the lack of leading edge devices with a very large wing area, and consequently low wing loading - and very large trailing edge flaps.
I think that there was a little difference in design philosophy between the two plane.
The Tu-95 was supposed to fly so fast that subsonic fighters of the 50'es couldn't catch it before they ran out of fuel. (Same philosophy as the Tu-16 and the B-47, but with vastly expanded unrefuled range).
The B-52 was supposed to fly so high up that fighters (subsonic or supersonic) couldn't reach it, or at least couldn't maneuver in the thin air in case they managed to get up there. The combination of low wing loading and jet engines made the high altitude possible.
Both philisophies are of course totally outdated today.
Always keep your number of landings equal to your number of take-offs, Preben Norholm
Rampart From United States of America, joined Aug 2005, 1755 posts, RR: 11 Reply 71, posted (5 months 1 week 3 days 1 hour ago) and read 3262 times:
Quoting FlyDeltaJets87 (Reply 60): Quoting EMB170 (Reply 56):
Keesje, it's a nice drawing...I have one question, though. If you're designing a propliner in the 140-160 seat range category, the FAA/JAA would probably mandate that you have mid-cabin emergency exits underwing (at least 2 and possibly 4). Would that be possible with the props outside the window or would that be too dangerous?
There are mid cabin emergency exits under the wing in Reply 7. The safety demo and safety card would need to clearly show the escape route being away (aft) from the props.
The Convair turboprops (and pistons?), the Britannia, HS 748, YS-11 all seem to have managed with an over-wing exit.
GFFgold From Indonesia, joined Feb 2007, 398 posts, RR: 0 Reply 72, posted (5 months 1 week 3 days ago) and read 3212 times:
Quoting Saab2000 (Reply 26): The public distaste for turboprops could be eliminated with good marketing and an exceptional product with legitimately lower costs.
Firefly in Malaysia marketed on 'putting the fun back into flying' and I think that could be developed further. Also, if your new turboprops are more comfortable inside, service is more personal and attentive, and you suggest that the customer is getting something tangible back from the saving in operating cost (and not just the airline's shareholders) then I don't think it is such a hard sell.
R2rho From Germany, joined Feb 2007, 961 posts, RR: 1 Reply 73, posted (5 months 1 week 2 days 14 hours ago) and read 3042 times:
Quoting Prebennorholm (Reply 70): You tell us that 842rpm = tip speed 290 m/s = Mach0.68 - which I haven't checked, but it seems to be very good figures, which I have every reason to trust. But that speed is the propeller tip within the propeller disk.
Actually those numbers are also quoted from airbusmilitary.com
Thanks for doing the further calculations, they give a pretty good idea of where the A400M lies, and therefore what a modern prop could achieve.
AirbusA6 From United Kingdom, joined Apr 2005, 1193 posts, RR: 0 Reply 74, posted (5 months 1 week 2 days 13 hours ago) and read 2992 times:
The rise of the LCC carriers espeically FR, shows that passengers are prepared to put up with a lot, for cheap prices, so surely a slightly slower, but much more economical aircraft fits in perfectly with their ethos? Or would the slower times mean that each plane would do less cycles per day, and hence lose it's economic benefit?
FlyBE have expanded rapidly with Q400s (soon they will gave 60) and I'm not aware of terrible public reaction?
it's the bus to stansted (now renamed national express a4 to ruin my username)
RayChuang From United States of America, joined Jun 2000, 7141 posts, RR: 8 Reply 75, posted (5 months 1 week 1 day 2 hours ago) and read 2609 times:
I think thanks to modern technology, a turboprop airliner's perception as "slow and noisy" will so be going the way of the dodo bird.
Keejse's Turboliner design proves that you can build a turboprop airliner that seats about the same as the 124-seat configuration that Southwest Airlines uses for the 737-300/700, but cruises at a very impressive Mach 0.7 (fast for a turboprop airliner), have very low noise (thanks to modern scimitar-shaped propellers in a eight-blade configuration to reduce supersonic blade noise), and burn fuel at around 20% lower rate on a per seat basis than a 733/73G. Like I said earlier, since some of Southwest's most important routes are the intra-California and intra-Texas routes, this could means substantial fuel savings these high-frequency flights, where because of the relatively short flight distances means flight travel time won't be much different than now with the 733/73G.
Hasnt Southwest always taken a specifically 737 subtypes only fleet policy for money saving? I doubt that anything but revolutionary fuel savings would get them to introduce a new type/type family into their fleets. But if anything would yield those savings in the near term it would pretty much deffinately be a turboprop.
Gliding is to power flying as seduction is to rape.
RayChuang From United States of America, joined Jun 2000, 7141 posts, RR: 8 Reply 78, posted (5 months 1 week 9 hours ago) and read 2265 times:
GST,
The big problem for Southwest nowadays is that with the high cost of fuel, the 737-300/700 has started to become less economical to fly on the shorter intra-California and intra-Texas routes, both of which are highly-patronized by a lot of business passengers.
This is where Keejse's Turboliner in a circa 125-130 seat configuration makes a lot of sense, especially when the fuel burn could be 20% lower than a 733/73G. That's very large fuel savings, savings that is more than enough to justify the cost of buying a new plane type.
Jambrain From United Kingdom, joined Sep 2008, 174 posts, RR: 11 Reply 79, posted (5 months 1 week 7 hours ago) and read 2171 times:
Quoting Prebennorholm (Reply 48): In cruise the engines are there to overcome drag. Drag is very much the same 5.5 to 6% of the weight of the plane whether it is cruising at Mach 0.8 at FL350 or Mach 0.6 at FL250. But in the later case you will spend more time and energy overcoming that drag
What do you mean?
Energy = Force x Distance
Same force 2x the speed needs 2x the power for 0.5x the time (i.e. same Energy)
Jets need to fly high to be efficient as jet SFC is terrible at low % power / RPM so they fly high to find thin air that reduces the thrust until it matches the drag.
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That, I'm afraid, is the Achilles heel for this concept, much as I'd like to see a revival of sensible turboprops. If regional jets are said to be a burden on that air traffic flow at the major airports (don't know if that's true except for numbers of them that might be more rational with consolidated larger capacity), large turboprops would slow the net flow for everyone. What would be the solutions? Dedicated turboprop altitudes or lanes?
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