Why are some aircraft still powered by propellers?

[Wookey]

Now that 'jet' engines are so reliable, come in all shapes and sizes (!) etc, why are some aircraft types still using propellers? Surely as there are more moving parts (gearbox, prop pitch controls etc) thery must be more expensive to maintain and possibly less economic to run?
Would appreciate some answers from the experts on this little conundrum that has been running around my brain for some time!
Hope this is in the right forum - Mods feel free to relocate if you think appropriate!

[Johnny F@rt Pants]

They are simply far more fuel economical. They are ideal for short hops where the difference in speed only makes a few minutes difference to the sector length, but the fuel saving is large, especially when these sectors are repeated several times per day.

As far as maintenance costs, I don't know, but I doubt there being a substantial difference.

[Dr Jekyll]

Most modern jet engines are turbofans of such high bypass ratio that the compressor acts largely as a propellor anyway.

[chevvron]

Yes, thermal stress caused my multiple startup/shutdown cycles would mean poorer reliability than a piston engine.

[Tu.114]

Allow me a comparison here between the F-70 and the DH8-400. However different those may look, they are rather similar in that they carry a load of 80 passengers on intra-European routes in my company and are often interchanged on several routes on shortest notice.

The Fokker does its job at M.75 and FL350. Its MTOW is dependent on certification, but ranges between 37 and 41 tons. Fuel flow in cruise is slightly below 2000 kg/h.

The DH8 on the other hand flies M.6 at FL250, which results in 60kTAS less (comparing flight plan speeds here). Its MTOW is just below 30 tons, and the fuel flow in cruise is at approx. 1150 kg/h.

So You trade in 5 minutes of flight time on a typical route in return for much lower fuel costs, reduced ATC and landing fees (those are weight dependent!). Additionally, the lower fuel consumption of the DH8 allows for strategic tankering much more often than the Fokker, making use of the fuel price differences between airfields. Even on longer routes like VIE-KIV or VIE-BSL, taking the fuel for both the inbound and outbound leg on one field is possible on the DH8 with medium passenger loads.

So a turboprop is an accountants best friend. The passengers on the other hand seem to prefer an old, beaten-up 707 to a factory-fresh DH8 judging from their looks when boarding...

[Phileas Fogg]

Not sure that I would have liked to have travelled VIE/LED/VIE on a turbo-prop though!

[The SSK]

Tu's mob have flown me BRU-VIE on Dash-8s several times, I've also done BRU-ZAG. After the first hour and a half, it begins to wear you down.

[Tu.114]

Yes, those savings come at a price - if You were seated somewhere in the vicinity of the propellers on Your flights, I do feel Your pain indeed. I usually advise passengers to select a seat in the rear of the cabin on the -400. Not only is it way quieter there than up front; one can also usually conveniently use the rear airstair for quick boarding and deboarding.

And let us not forget that there are nasty corners also in jet aircraft. Continuing the comparison between the DH8 and the F70 - while the noisy area in the DH8 is in the 1st third of the cabin, the F70 will rattle Your dentures when seated in the last few rows between the engines and top it off with a whiff from the outhouse drifting by every now and then.

[The SSK]

If I'm not mistaken, you seat your Business passengers at the front, which is where the noise is. In the heyday of mainline prop service, the F/C cabin was at the back.

I once flew London-Warsaw-London in an Il-18, about three hours each way. Outbound, I was near the front and it was just hell. On the return I grabbed a seat at the back and the difference was remarkable.

[Tu.114]

You are not mistaken, and I do agree with You that this is the least desirable location for the C class from a comfort standpoint. And this is both from the passengers and the cabin crews point of view - the galley is located in the rear as well, and many have complained already about the long ways carrying the C meals through the starving eco cabin.

However, I have been told that surveys were held in the company and many C passengers were not willing to travel in more comfort if it meant no longer sitting up front, having the coveted 1A as a seat or - God forbid - having to board via the servants entry in the rear. Well, I am getting a bit cynical here, but still, psychology is a force to be reckoned with. Maybe this is just a freshly formed habit; I have seen several floor plans of propliners that showed the premium cabin to the rear. When those were more prevalent, passengers knew what to expect, but now that in all the jet airliners, the premium classes are up front, this habit may be hard to break.

[Smoketrails]

So am I the only one who gets excited when flying on DH8D, or any other high winged prop in matter of fact!? Love sitting next to the engine and watching the undercarriage go up and come down. And the when the aircraft is cleaned up after take off you have a fantastic unrestricted view of everything below you...

[DaveReidUK]

I once flew London-Warsaw-London in an Il-18, about three hours each way. Outbound, I was near the front and it was just hell. On the return I grabbed a seat at the back and the difference was remarkable.

I seem to recall that the Vanguard had the posh seats at the back, doubtless for the same reason.

[The SSK]

However, I have been told that surveys were held in the company and many C passengers were not willing to travel in more comfort if it meant no longer sitting up front, having the coveted 1A as a seat or - God forbid - having to board via the servants entry in the rear.

Priceless. Next time I shall request a downgrade and see what reaction I get.

[pax britanica]

I love turbo props and enjoyed every flight I made on them even if at times the comfort factor was abit lacking. Giving away my age Ive tried
Viscount , Herald , F27, DHC3(STOL) Twotters, ATR 43 and 72 F50 and Q 400.

Like an earlier contributor I love the view and the sight of that massive gear in transit.

Noise is an issue that's true and sitting at the back also means that you never have to worry about the awful prospect of a prop coming loose as 3mm of aluminium wont stop that .

TPs also make some cool noises with pitch change on take off and on finals and can do neat stuff like reversing on the runway at Anguilla WI to make sure they got to use every inch of it (and they needed to)

Also gave me a memorable trip on a Lufthansa F50 empty except for me and a couple asleep at the back from Arlanda to Templehof and the landing at Templehof on the jump seat was amazing. That crew also remarked on how pax failed to understand that their F50 was shiny and new with modern avionics (for 1993) compared to the antique, even then, jet options available (737-200 and DC9-20).

The equally friendly crew on the DHC 3 were also proud of their brand new STOL machine and again let me use a v cramped jump seat for take off from one of Washington Nationals secondary runways on a commuter flight up to JFK.

So I am big fan and hope that they will be around for along time yet serving the less glamorous but often more exciting airports. Mind you they are better ride in fair weather than the nasty stuff.

[FakePilot]

For some reason I always prefer "prop-jobs" over jets.

[DaveReidUK]

The equally friendly crew on the DHC 3 were also proud of their brand new STOL machine

You might want to check your Jane's ...

[Rwy in Sight]

They are fine aircraft - provided they allow the airline to sell cheaper tickets.

[Capetonian]

I love the sight and sound of a turboprop and enjoy flying on them despite the higher noise levels. It reminds me of the old days of flying round central Africa on Viscounts and DC3s.

They seem to have lower takeoff and landing speeds than jets and somehow that makes me feel safer, which might be completely irrational and incorrect.

[dc9-32]

Tu's mob have flown me BRU-VIE on Dash-8s several times, I've also done BRU-ZAG. After the first hour and a half, it begins to wear you down.

I once flew as crew on an Antonov AN22, Novosibirsk to Okinawa (avoiding China) and trust me, after the first 2hrs, I'd had enough but had 9 more to go :ugh:

[grollie]

Mind you not as loud as sitting in a Fat Albert/Shacketons (mind you i was paid to in those days in RAF) done trips in Viscounts Heralds F27 ATPs S360 S330 King Airs and many more and i remember those trips with fondness

[pax britanica]

Dave Reid

I was lazy and didn't check -you are of course 100% right and it was a DHC 7 , four engines for 40 odd pax and a very impressive airplane too.

Belonged to Henson Airlines and flew as Allegheny Commuter which through the convolutions of the US Airline industry is now American Airlines.

[Smoketrails]

I once flew as crew on an Antonov AN22, Novosibirsk to Okinawa (avoiding China) and trust me, after the first 2hrs, I'd had enough but had 9 more to go*

Lucky B*st*rd!:)

[Talkdownman]

The turboprops are also the controllers friend when it comes to speed versatility. Generally they can keep ATC spacing speeds for longer and later and decelerate much more quickly. At a place like London City for example it was always easier to put the turboprop ahead of the turbojet which wanted to slow down earlier. Conversely if you stuffed a turboprop up too tight behind a turbojet it could disc-up the props and give you minimum safe approach speed in seconds. If a turbojet is stuffed-up too tight behind a turboprop the prop can more readily minimise runway occupancy and make the first exit.

[Tarq57]

Talkdownman, by that rationale, I guess you'd consider the venerable quadrapuff to be in the turboprop category?:E

[Talkdownman]

quadrapuff? If that's four hair dryers, then no.

[Phileas Fogg]

Two screws are better than four blow jobs :)

[dubbleyew eight]

point of order.

there is not a single aircraft in the world powered by a propeller.
they are powered by the engine that drives the propeller. :=

[Tu.114]

Talkdownman - indeed, a turboprop can brake rather quickly. On occasion, this catches (inexperienced?) controllers out cold though. On approach, us getting a bit close to the preceding jet for his liking, the director once had us (flying a DH8-300) "Reduce now to minimum approach speed". Well, if this is what he wants, this is what he gets: a reduction from 160ish to about 105 kIAS within an instant.

Followed about 15 seconds later by the polite question if we would mind speeding up again a little bit for the benefit of the succeding traffic...

[Phileas Fogg]

I recall riding the RHS of a DHC6 into LGW one morning with a screaming headwind, it seemed like it took forever and a day just to fly across the staff car park, asked if we could expedite a quick exit at "Charlie" we expedited an even quicker exit at "Bravo".

The DHC7 was even more fun, in crosswind conditions they'd land across St. Mawgan's 300' wide runway. :)

[Super VC-10]

Of course, the biggest advantage (as a pax) with a prop or turboprop aircraft is that you can tell that the engine is working.:ok: Best flight I ever had was in a DH89B, four wings, two piston engines, one take-off and five landings! :D

[studentpilotmcuk]

I remember my first ever flight on a prop aircraft. My family and myself were flying Humberside to Toronto via Schipol. We were on a Shorts 360 Air UK and then Canadian Pacific DC10.

Having traveled extensively in Europe I can say that I prefer the jets to props any day. Although I do have fond memories of the Shorts 360 and the F27

[Talkdownman]

At LHR the Brymon Dash 7 simply wanted to know whereabouts to vacate and invariably touched down in the 'block' containing the turn-off. On 09L this usually had to be Block 9 with one behind over the numbers, but when it was quiet it would fly the length of the runway touching down as close to the stand as possible. (I recall a lady slightly over-cooked it one day and just came to a halt at the 09L stop-end for 19/27...I believe a bit of beta sorted it out)

[Hartington]

Wasn't there a DC9 derivative that had an "open rotor" fitted (port side?) for testing at one point? The point being that I've always thought that the fan of a jet could be referred to as a "shrouded propeller" if you're willing to strech a point.:confused:

[AdamFrisch]

It was called the UDF - Unducted Fan. Noisy, but saved a lot of fuel. Unfortunately the development was an oil crisis child and coincided with massively reducing oil prices which killed it off. For now. It will come back.

There is basically no way of increasing efficiency without increasing the fan size of fanjets. We're almost at the limit today with the Trents and the GEnx - the airplane makers have to incorporate bigger and bigger fan casings under the wings, increasing the landing gear height and adding structural weight and in the future it will become impractical to encase that big fan. So the unducted fan - basically a glorified turboprop - will come back.

Moving lost of air slower is always more efficient than moving less volume faster. So the bigger you can make a fan, the more efficient it will be.