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Question About Turbo-props

Thu Jul 12, 2001 7:18 am

Why is it that whenever I fly a Dash-8, the engines sound like they are just above idle even during take-off, yet when I fly in any other turbo-prop (such as the Beech 1900), the engines scream?
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Joined: Thu Jun 21, 2001 11:07 am

RE: Question About Turbo-props

Thu Jul 12, 2001 12:57 pm

From my understanding of Turboprops is their are two basic designs. One, being where the prop is connected directly to its own independent turbine. And two, where the prop is connected to the camshaft through a reduction gear box. One of these is louder than the other, but which one I don't know. Look up pratt-whitney.com, Look at the PW100 and the PT6A-large for more details.
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RE: Question About Turbo-props

Thu Jul 12, 2001 4:08 pm

have you taken into consideration that the newer dash 8's coming out have noise, and vibration dampening?

The ATR keeps the vibration to a minimum, but it can get loud at times, especially when the prop is set at a high RPM, and the turbine is near 100 percent N1, as in takeoff

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T prop
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RE: Question About Turbo-props

Thu Jul 12, 2001 4:29 pm

What you're hearing is the propellers. For a Dash 8 100 series with it's 13 foot diameter props max NP is 1200 rpm, in a climb rpm it's 1050 and in cruise they turn only 900 rpm.

I don't remember what the exact RPMs are for the smaller Beechcraft props but I think they run in the vicinity of 2200 rpm.

The difference in rpm's of these two aircrafts props makes them sound the way they do.

BTW the Dash8 400's props turn 1020 rpm for T/O and 850rpm in cruise. Slow turning props are what helps make them as quiet as they are.

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