Moderators: richierich, ua900, PanAm_DC10, hOMSaR
ArcticFlyer wrote:Part of the turboprop vs. turbofan debate is controlled by what passengers want to fly in. Jets are seen as modern and safe while turboprops are seen as antiquated "puddle-jumpers" regardless of the fact that there is absolutely no data to back up these perceptions. Several years ago I flew for an RJ operator in the northeast and our shortest route was PHL-ABE (45 nm I think). On such a short flight there is absolutely no difference in flight time on a jet vs. a turboprop, but trip fuel and therefore cost will be much higher. The only reason we flew routes like that was because uninformed passengers want jets.
On a larger scale, note that PT and C5 were strictly turboprop operators as recently as 10 years ago but now they're both all-jet. I think QX is the only "regional" still flying turboprops (Q400s in their case) in the USA.
GalaxyFlyer wrote:Very empty RJ above F400, certainly no CRJ.
GalaxyFlyer wrote:Very empty RJ above F400, certainly no CRJ.
kalvado wrote:WHat is the usual cruise of a turboprop? Service ceiling is an official number from the datasheet - easy to find, easy to verify...
ArcticFlyer wrote:GalaxyFlyer wrote:Very empty RJ above F400, certainly no CRJ.
Very true, spoken from experience. Mid-high 20s was our typical domain; even 310 was a struggle. Did 370 once but that was on an empty repo flight so it really doesn't count.kalvado wrote:WHat is the usual cruise of a turboprop? Service ceiling is an official number from the datasheet - easy to find, easy to verify...
When I was flying the DHC-8 we typically cruised in the low 20s on flights longer than about an hour. Max certified altitude was FL250 but that was due to not having drop-down oxygen masks for the pax, not a performance limitation. I think it could have gone quite a bit higher but due to mach effects there really would have been no benefit in doing so; once we were above the mid-teens TAS pretty much stayed the same and fuel flow only improved marginally.
Jackonicko wrote:How much more environmentally friendly is a modern turboprop than an equivalent sized turbofan-powered airliner in terms of environmental impact?
Roughly 30% lower fuel burn per passenger seat/mile?
Lower flying and less likely to contrail?
Lower flying and releasing emissions at a 'better' height?
A better 'neighbour' in terms of noise?
Is there an environmental argument for making greater use of turboprops for short haul?
How do the new generation of Open Rotor Fans/Unducted fans/Propfans compare?
Any thoughts?
What am I missing?
kalvado wrote:what about "above the weather" part - can you comment?
GalaxyFlyer wrote:Very empty RJ above F400, certainly no CRJ.
ArcticFlyer wrote:kalvado wrote:what about "above the weather" part - can you comment?
It all depends on where you're flying. In Alaska or Northern Canada the low 20s is plenty to get you above 99% of the bad weather even in the summer; I can remember only once in several years being faced with a line of thunderstorms (south of Fairbanks) that we couldn't outclimb and was dense enough to make it challenging to pick our way through. On the other hand, even FL370 is nowhere near high enough to get above the buildups I routinely see crossing the Great Plains during the summer months and we're usually too heavy to even make it to FL370 anyway.
Technically there is no reason a turboprop couldn't be designed to fly higher, in fact I think the Saab 2000 goes up into the low 30s. As evidenced by the type's meager sales (63 over 7 years of production), there simply isn't a large market for such an airplane. Turboprops will never be as fast as jets making them unsuitable for longer flights, while for shorter routes where they might make economic sense they suffer (at least in America) from passenger bias in favor of jets as I have stated in prior posts.
Nicoeddf wrote:GalaxyFlyer wrote:Very empty RJ above F400, certainly no CRJ.
I have been doing 400 and 410 in the CR9 with reasonable loads (2:20h block times, 28 tons ZFW, about 33 tons TOW. No issue.
GalaxyFlyer wrote:Nicoeddf wrote:GalaxyFlyer wrote:Very empty RJ above F400, certainly no CRJ.
I have been doing 400 and 410 in the CR9 with reasonable loads (2:20h block times, 28 tons ZFW, about 33 tons TOW. No issue.
“No CRJ” was a blanket statement in error, huge difference in perf for the 700/900 than the the original 200. My brief experience was in the 850 corporate version, which was a dog, perhaps worse than the -200.
kalvado wrote:As far as I remember, service ceiling is a significant factor. Dash-8 and ATR are limited below FL300, while RJ can go over FL400.
gloom wrote:kalvado wrote:As far as I remember, service ceiling is a significant factor. Dash-8 and ATR are limited below FL300, while RJ can go over FL400.
Are you aware it's not a powerplant limit, but a general choice of aerodynamic efficiency vs payload vs range?
There are turboprops able to go way above F300. Dash8 and ATR are optimized for short hops.
Cheers,
Adam
kalvado wrote:What is reasonably achievable if someone has some loose change of couple $10Bs? Reasonable for, say, NYC-FL service with longer trip with "it's green!" slogan? How would operational economics look like?
Would a FL450 ceiling be feasible and beneficial?
Jackonicko wrote:How much more environmentally friendly is a modern turboprop than an equivalent sized turbofan-powered airliner in terms of environmental impact?
Roughly 30% lower fuel burn per passenger seat/mile?
Lower flying and less likely to contrail?
Lower flying and releasing emissions at a 'better' height?
A better 'neighbour' in terms of noise?
Is there an environmental argument for making greater use of turboprops for short haul?
How do the new generation of Open Rotor Fans/Unducted fans/Propfans compare?
Any thoughts?
What am I missing?
kalvado wrote:Well, a bigger picture:
I am pretty sure that, should turboprop operation be actually cheaper than turbofan, we would see at least some "Fly green! Save the planet and pay less!" operations even with current types. There is definitely some cohort to bite on such approach, and NYC-CHI may be a reasonable range without good ground competition. Why it doesn't happen?