flyboy80
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Q400's "slow" Moving Props.

Wed Dec 28, 2005 5:21 am

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!
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FlyHoss
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RE: Q400's "slow" Moving Props.

Wed Dec 28, 2005 5:28 am

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.
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Boeing7E7
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RE: Q400's "slow" Moving Props.

Wed Dec 28, 2005 7:29 am

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.
 
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Starlionblue
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RE: Q400's "slow" Moving Props.

Wed Dec 28, 2005 8:43 am

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.
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320tech
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RE: Q400's "slow" Moving Props.

Wed Dec 28, 2005 1:51 pm

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".
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bri2k1
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RE: Q400's "slow" Moving Props.

Wed Dec 28, 2005 3:46 pm

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?
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tbanger
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RE: Q400's "slow" Moving Props.

Wed Dec 28, 2005 6:25 pm

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.
 
cfalk
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RE: Q400's "slow" Moving Props.

Wed Dec 28, 2005 8:39 pm

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.
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Goldenshield
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RE: Q400's "slow" Moving Props.

Wed Dec 28, 2005 11:32 pm

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.
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2H4
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RE: Q400's "slow" Moving Props.

Wed Dec 28, 2005 11:54 pm




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.




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flyboy80
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RE: Q400's "slow" Moving Props.

Thu Dec 29, 2005 2:06 am

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.
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Ralgha
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RE: Q400's "slow" Moving Props.

Thu Dec 29, 2005 5:46 am

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.
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Goldenshield
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RE: Q400's "slow" Moving Props.

Thu Dec 29, 2005 7:28 am

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.)
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sanjet
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RE: Q400's "slow" Moving Props.

Thu Dec 29, 2005 10:50 am

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
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Ralgha
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RE: Q400's "slow" Moving Props.

Thu Dec 29, 2005 12:43 pm

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.
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Goldenshield
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RE: Q400's "slow" Moving Props.

Thu Dec 29, 2005 9:42 pm

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]
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bri2k1
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RE: Q400's "slow" Moving Props.

Fri Dec 30, 2005 7:26 am

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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