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Q400's "slow" Moving Props.  
User currently offlineFlyboy80 From United States of America, joined Jul 2001, 1876 posts, RR: 3
Posted (8 years 7 months 6 days 18 hours ago) and read 3806 times:

I was doing a little research, In the process, noted that the props that are used on the Q400 are often described as “slow moving.” I’m curious to know how much slower they are as opposed to earlier generation power plants. What are the benefits, Lower noise, vibration? I believe the engines on the Q400 are the PT2000? Also, when it comes to efficiency, how efficient are these engines in fuel consumption/ engine maintenance as compared to earlier models. The Q400’s “Turbo Profits” seem too good to be true, orders don’t necessarily seem to reflect that aspect however.
Thanks for the info!
Bri/EUG

16 replies: All unread, jump to last
 
User currently offlineFlyHoss From United States of America, joined Feb 2005, 598 posts, RR: 0
Reply 1, posted (8 years 7 months 6 days 18 hours ago) and read 3800 times:

I believe the engines are PWC 150A's of about 4580 (max) shaft horsepower. I don't recall what the prop rpm ranges are, though. Q does stand for quiet; generally, the slower the prop rpm, the less the noise and vibration.


A little bit louder now, a lil bit louder now...
User currently offlineBoeing7E7 From , joined Dec 1969, posts, RR:
Reply 2, posted (8 years 7 months 6 days 16 hours ago) and read 3763 times:

6 Blades allow a slightly slower spin rate which reduces noise and permits higher speed. As for the efficiency, they burn the same amount of gas in an hour as a 50 seat RJ and the block times out to 350 miles are within 10 minutes, and are identical inside of 250 miles.

If an airline wants to make money to small markets from their hubs, this is the plane to do it with.


User currently offlineStarlionblue From Greenland, joined Feb 2004, 17001 posts, RR: 67
Reply 3, posted (8 years 7 months 6 days 15 hours ago) and read 3734 times:

Quoting Boeing7E7 (Reply 2):
As for the efficiency, they burn the same amount of gas in an hour as a 50 seat RJ and the block times out to 350 miles are within 10 minutes, and are identical inside of 250 miles.

If an airline wants to make money to small markets from their hubs, this is the plane to do it with.

OT of course, but I agree completely. The love affair with RJs went a bit too far.



"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently offline320tech From Turks and Caicos Islands, joined May 2004, 491 posts, RR: 5
Reply 4, posted (8 years 7 months 6 days 10 hours ago) and read 3683 times:

The "Q" in Q400 indicates active noise suppression in the cabin. The smaller models with more conventional props are also Qsomething.

The love affair with RJs went a bit too far.

Couldn't agree more, unfortunately the travelling public often associates "propellers" with "old", "unsafe", and "slow".



The primary function of the design engineer is to make things difficult for the manufacturer and impossible for the AME.
User currently offlineBri2k1 From United States of America, joined Dec 2004, 988 posts, RR: 4
Reply 5, posted (8 years 7 months 6 days 8 hours ago) and read 3660 times:

I prefer jets when they can get out of the clouds. Flying around the northeastern US in a Dash-8, you never get out of the clouds, and the constant "ping, zing" noises from ice breaking off and hitting the fuselage gets old. For other trips, though, a turboprop ride is a lot of fun. When I fly to ONT, I try to get a flight to LAX and then take an EMB-120 over to ONT. It's a 15-minute flight for which I get 500 frequent-flier miles, and it's something out of the ordinary -- flying on a propellor-driven plane (which I'm not piloting  Smile)

I had someone who was training for the airlines once (Mesa Air I think) tell me that EMB-120s weren't very good, and the only way to fly them right was to "be able to survive a prop overspeed." I was pretty sure he was just trying to sound cool, but at the time, I didn't know much about constant-speed props, turboprop powerplants, or anything else. I guess I still don't know enough, because I don't know what to think of his comment. Does anyone have any ideas?



Position and hold
User currently offlineTbanger From Australia, joined Jul 2004, 266 posts, RR: 0
Reply 6, posted (8 years 7 months 6 days 5 hours ago) and read 3634 times:

Takeoff = 1020rpm
Climb = 900rpm
Cruise = 850rpm

I imagine these figures are only marginally lower than the 4 bladers found on the smaller Dash's. (Maybe <100rpm)

Noise is reduced jointly by the slower turn speed and also by the blended shape of the blades. The shape of the blades would also allow for less drag, hence slower speed required to provide a given thrust.


User currently offlineCfalk From , joined Dec 1969, posts, RR:
Reply 7, posted (8 years 7 months 6 days 3 hours ago) and read 3614 times:

Quoting Bri2k1 (Reply 5):
When I fly to ONT, I try to get a flight to LAX and then take an EMB-120 over to ONT

There is a huge difference between an old turkey like the EMB-120 and a Dash-8-400. That's like comparing a DC-9-10 to a B717.


User currently offlineGoldenshield From United States of America, joined Jan 2001, 5970 posts, RR: 14
Reply 8, posted (8 years 7 months 6 days ago) and read 3577 times:

Quoting Cfalk (Reply 7):
There is a huge difference between an old turkey like the EMB-120 and a Dash-8-400.

It may be an 'old' turkey, but it plenty of performance for it's size.



Two all beef patties, special sauce, lettuce, cheese, pickles, onions on a sesame seed bun.
User currently offline2H4 From United States of America, joined Oct 2004, 8955 posts, RR: 60
Reply 9, posted (8 years 7 months 6 days ago) and read 3572 times:
AIRLINERS.NET CREW
DATABASE EDITOR




Quoting Tbanger (Reply 6):
Noise is reduced jointly by the slower turn speed and also by the blended shape of the blades.



...Don't forget the noise cancellation system used in the cabin:



The Q Series is equipped with the revolutionary new system called NVS that reduces sound and vibration at their sources - even vibrations below the audible threshold. The system works effectively by reducing the vibrations in the fuselage, thus stopping much of the noise from entering the cabin to begin with. The benefit is most dramatic in the seats closest to the arc of the propellers, but is also very noticeable throughout the cabin.

NVS is unique to the Q Series and is the world's first application of this technology in an airliner cabin.

How does it work?

The majority of noise and vibration in a turboprop cabin is caused by the 'pulses' of air that hit the side of the aircraft fuselage, created by the turning of the propeller. This in turn causes the fuselage to vibrate, and transmit both noise and vibration into the cabin.

The NVS system reduces this fuselage vibration through leading edge active control technology.








The diagram below illustrates the peaks of energy created by the air pulses, and the reduction in these peaks through the use of the active control technology.








During flight, microphones concealed throughout the cabin transmit noise information to a special on-board computer that also receives the propeller speed. The computer continually analyzes this information and signals devices called Active Tuned Vibration Absorbers (ATVAs) mounted on the fuselage frames. The ATVAs then produce out-of-phase counter vibrations, so that the original vibrations are significantly reduced.










...From http://www.q400.com/q400/en/quiet.jsp.




2H4





Intentionally Left Blank
User currently offlineFlyboy80 From United States of America, joined Jul 2001, 1876 posts, RR: 3
Reply 10, posted (8 years 7 months 5 days 21 hours ago) and read 3540 times:

My brother works at skywest, and he's telling me the EMBs they operate are the "hot and high" version, and at this, hey can't even make it EUG-PDX without a three seat weight restiction.
bri/eug


User currently offlineRalgha From United States of America, joined Nov 1999, 1614 posts, RR: 6
Reply 11, posted (8 years 7 months 5 days 18 hours ago) and read 3477 times:

Quoting Bri2k1 (Reply 5):
I had someone who was training for the airlines once (Mesa Air I think) tell me that EMB-120s weren't very good, and the only way to fly them right was to "be able to survive a prop overspeed." I was pretty sure he was just trying to sound cool, but at the time, I didn't know much about constant-speed props, turboprop powerplants, or anything else. I guess I still don't know enough, because I don't know what to think of his comment. Does anyone have any ideas?

He's just trying to sound cool. A prop overspeed in any turboprop would be quite exciting. It's not like it's common though.

Quoting Cfalk (Reply 7):
There is a huge difference between an old turkey like the EMB-120 and a Dash-8-400.

Yes, but the Brasilia is probably the best performing turboprop airliner after the Q400. Faster than any of the other turboprop airliners, and most turboprops overall. It's also built like a tank, it'll take just about anything thrown at it. The only bad part about its flying characteristics is having to adjust the rudder trim after most power changes.

Quoting Flyboy80 (Reply 10):
My brother works at skywest, and he's telling me the EMBs they operate are the "hot and high" version, and at this, hey can't even make it EUG-PDX without a three seat weight restiction.

More commonly known as the EMB-120ER (as opposed to the RT). PDX to EUG isn't long enough to allow a takeoff at max weight, so that can sometimes hurt the payload capacity depending on how much fuel is required. Also, with the new CG system the FAA implemented, the aft-galley Brasilias are restricted due to CG rather than weight. Pretty stupid really since they flew fine under the old system. How many people they can take depends on how many bags are in the back, and how heavy the airplane is empty. I've been able to sit in the jumpseat with all the seats in back filled after the new weight/CG system was started. We fit all the desired bags in too. It all depends.



09 F9 11 02 9D 74 E3 5B D8 41 56 C5 63 56 88 C0
User currently offlineGoldenshield From United States of America, joined Jan 2001, 5970 posts, RR: 14
Reply 12, posted (8 years 7 months 5 days 16 hours ago) and read 3451 times:

Quoting Ralgha (Reply 11):
PDX to EUG isn't long enough to allow a takeoff at max weight, so that can sometimes hurt the payload capacity depending on how much fuel is required.

PDX-EUG is landing weight restricted; the payload would be hurt much worse on a long flight. Besides that, there is more than enough room between MZFW and MLDW to take extra gas, should it be needed. Heck, I've done LAX-ONT roundtripped, with ONT as the alternate going back to LAX, and both legs with a full load (numbers-wise.)



Two all beef patties, special sauce, lettuce, cheese, pickles, onions on a sesame seed bun.
User currently offlineSanjet From Canada, joined Mar 2005, 180 posts, RR: 0
Reply 13, posted (8 years 7 months 5 days 13 hours ago) and read 3416 times:

Quoting Tbanger (Reply 6):

Takeoff = 1020rpm
Climb = 900rpm
Cruise = 850rpm

I imagine these figures are only marginally lower than the 4 bladers found on the smaller Dash's. (Maybe <100rpm)

On the 100's we take off at 1200RPM
Climb= 1050 or 900 (depending on type of climb)
Cruise= 900



Will Fly For Food!
User currently offlineRalgha From United States of America, joined Nov 1999, 1614 posts, RR: 6
Reply 14, posted (8 years 7 months 5 days 11 hours ago) and read 3396 times:

Quoting Goldenshield (Reply 12):
PDX-EUG is landing weight restricted; the payload would be hurt much worse on a long flight. Besides that, there is more than enough room between MZFW and MLDW to take extra gas, should it be needed. Heck, I've done LAX-ONT roundtripped, with ONT as the alternate going back to LAX, and both legs with a full load (numbers-wise.)

You guys should round trip the fuel far more often than you do. It would save a ton of money with the 40+ cent difference in fuel prices between some of the airports.



09 F9 11 02 9D 74 E3 5B D8 41 56 C5 63 56 88 C0
User currently offlineGoldenshield From United States of America, joined Jan 2001, 5970 posts, RR: 14
Reply 15, posted (8 years 7 months 5 days 2 hours ago) and read 3336 times:

Quoting Ralgha (Reply 14):
You guys should round trip the fuel far more often than you do.

It depends on the mission required on the next leg. In many cases, it's just cheaper to buy the gas, rather than pay for a small amount of gas, and a hefty call-out fee. Also, on some legs, we can't round-trip the fuel with a full payload on shorter segments like LAX-SAN without dipping into payload. Part of our job is to give you the most payload to play with, on top of balancing fuel requirements and costs, and since there isn't a large price difference (as is now, but before, there was a large difference) between LAX and SAN, in this case, then there is no point to tanker it through.

Of course, there will always be guys on both sides of the spectrum: those that don't care how much the fuel costs, and those who do, and are willing to save as much money as possible—even at the expense of paying passengers.

[Edited 2005-12-29 14:05:50]


Two all beef patties, special sauce, lettuce, cheese, pickles, onions on a sesame seed bun.
User currently offlineBri2k1 From United States of America, joined Dec 2004, 988 posts, RR: 4
Reply 16, posted (8 years 7 months 4 days 16 hours ago) and read 3240 times:

Quoting Cfalk (Reply 7):
There is a huge difference between an old turkey like the EMB-120 and a Dash-8-400. That's like comparing a DC-9-10 to a B717.

That's quite true, but the USAir Dash 8's I was referring to are not the -400 series. USAirways Express operates the 100, 200, and 300 series, but I've only flown on their -100 series, and they really couldn't get above the clouds from PHL-SYR!



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