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PT6 turboprop question

PostPosted: Tue Mar 01, 2011 10:28 pm
by snippyfsxer
Hi, this question is probably directed at "Crossfire"

I'm wondering about 'Climb Thrust' on the King Air that you fly.  How do you go about setting Climb power...do you always use Maximum available, meaning you have your needles right under the red lines for torque, Ng, and ITT

As you guessed, this question refers to the PT6A-35's on the new RealAir Royal Turbine Duke.  On these engines, the Redline Torque is 1250 lbs, and the max RPM is 2200.  After takeoff, I know that we would typically pull the RPMs back to 2000.  Now, assuming that my temps are within the green, what would be a good place to put the Torque?

(nfortunately, due to copyright reasons, the Perf charts that accompanied the original Piston Duke, are not available for reference in the Royal Turbine conversion)

Re: PT6 turboprop question

PostPosted: Wed Mar 02, 2011 5:08 am
by -Crossfire-
When I set climb power, I pull the torque back slightly (just so when I pull the props back, the torque won't go near or past red line).  Then I'll set props to 1900 RPM.

Other than that, as you climb, just keep increasing power to maintain the torque close to redline, providing  ITT and N1 are still within limits.

Re: PT6 turboprop question

PostPosted: Wed Mar 02, 2011 8:17 am
by snippyfsxer
[quote]When I set climb power, I pull the torque back slightly (just so when I pull the props back, the torque won't go near or past red line).

Re: PT6 turboprop question

PostPosted: Wed Mar 02, 2011 11:24 am
by C
[quote]
I have one more question, concerning descent in a GA turboprop.

Re: PT6 turboprop question

PostPosted: Thu Mar 03, 2011 1:46 am
by -Crossfire-
In a King Air with 4-bladed props (or any 4-blade turboprop), you can't decend at idle, because you'll be doing about 5000 or 6000 feet per min.

Re: PT6 turboprop question

PostPosted: Thu Mar 03, 2011 11:00 am
by C
[quote]In a King Air with 4-bladed props (or any 4-blade turboprop), you can't decend at idle, because you'll be doing about 5000 or 6000 feet per min.

Re: PT6 turboprop question

PostPosted: Thu Mar 03, 2011 5:35 pm
by snippyfsxer
Okay then, a 3 degree descent it is...

Just finished a flight descending at this angle, at close to Vmo (on this plane it is 235 kias), and was surprised to find it took about 900 ft-lbs for what averaged out to around 1300 fpm.  I would have thought a lot less power would be required.

Even though this plane didn't come with the kind of charts that I would have liked, I did manage to find some performance info elsewhere online for the PT6A-35 and was amazed to find that when I matched the torque and RPM settings to the chart at Standard conditions, that the fuel flow was within a tenth of a gallon. may two tenths of a gallon at most.

Re: PT6 turboprop question

PostPosted: Fri Mar 04, 2011 2:50 pm
by snippyfsxer
On a plane such as this, during the approach, when is it customary to move the prop levers fully forward?

Re: PT6 turboprop question

PostPosted: Fri Mar 04, 2011 3:47 pm
by C
[quote]On a plane such as this, during the approach, when is it customary to move the prop levers fully forward?

Re: PT6 turboprop question

PostPosted: Fri Mar 04, 2011 7:05 pm
by snippyfsxer
Thanks,

okay, but one more pestering question.

Re: PT6 turboprop question

PostPosted: Sat Mar 05, 2011 10:43 am
by -Crossfire-
[quote]Thanks,

okay, but one more pestering question.

Re: PT6 turboprop question

PostPosted: Sat Mar 05, 2011 2:12 pm
by snippyfsxer
[quote]
Make sense?