AVSIG: Turbine P-Baron wwswsigarch.jpg (7236 bytes)

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AVSIG Discussion Sections >> Beechcraft

Dave Siciliano (ADS)
Top Gun


Reged: 05/17/04
Posts: 8469
Loc: ADS (Dallas, TX)
Re: Turbine P-Baron
      09/20/08 07:42 PM

Quote:

When Hawker/Beech re-engined the C90 King Air to make the C90GT, they replaced 550shp PT6A-21 engines with 550shp PT6A-135A engines. Why bother, you say? Because the -135A engines are derated; they are thermodynamically capable of 750shp. So they can maintain full rated power of 550shp to a much higher altitude without overtemping. This make the C90GT almost 30 kt faster, and much better climb performance.




Thanks Mase! Robert, if you have the same amount of power; you'll true out faster higher up.
According to Conklin & de Decker:

Up to about 14,000 feet at ISA, the PT6A-21 delivers its full take-off torque. At recommended cruise, this is 1,315 Ft.- Lbs per engine. Above this altitude, the engine loses torque and at 26,000 feet produces only 862 Ft.-Lbs of torque. This yields 235 KTAS for a mid-weight King Air C90A.

Just to compare the -135s: and I quote again:
At normal cruise, the PT6A-135A produced 1,520 Ft-Lbs. up to 18,000 feet. At 26,000 feet is still produces 1,170 Ft-Lbs. torque - 36% more power than the PT6A-21.

So, constant torque on the -21 up to 14,000, then, it declines. For the -135s, torque remains constant up to 18,000 feet; then, declines. This is primarily do to a better compressor.

Did this answer your question? Sorry to get into the new engine, but it shows how the same power is made to a higher altitude.

Best,

Dave

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Entire topic
Subject Posted by Posted on
* Turbine P-Baron Dave Siciliano (ADS) 03/29/08 06:09 PM
. * * Re: Turbine P-Baron Jeff Hartmann CIC   06/15/08 01:11 PM
. * * Re: Turbine P-Baron Dave Siciliano (ADS)   06/15/08 01:49 PM
. * * Re: Turbine P-Baron Curtis Sanford (SQL)   06/16/08 02:05 AM
. * * Re: Turbine P-Baron Dave Siciliano (ADS)   06/16/08 03:06 PM
. * * Re: Turbine P-Baron Ralph Jones   06/16/08 03:12 PM
. * * Re: Turbine P-Baron Tom Tyson [SUW]   06/17/08 12:18 AM
. * * Re: Turbine P-Baron Tom Tyson [SUW]   07/29/08 02:20 PM
. * * Re: Turbine P-Baron Jeff Hartmann CIC   06/15/08 04:48 PM
. * * Re: Turbine P-Baron Dave Siciliano (ADS)   06/15/08 05:00 PM
. * * Re: Turbine P-Baron Dave Siciliano (ADS)   09/19/08 08:07 PM
. * * Re: Turbine P-Baron Scott Dyer [HPN/NY]   09/19/08 09:09 PM
. * * Re: Turbine P-Baron Dave Siciliano (ADS)   09/19/08 10:48 PM
. * * Re: Turbine P-Baron Scott Dyer [HPN/NY]   09/20/08 12:02 AM
. * * Re: Turbine P-Baron Robert Mann [HPN-NY]   09/20/08 03:41 AM
. * * Re: Turbine P-Baron Dave Siciliano (ADS)   09/20/08 12:25 AM
. * * Re: Turbine P-Baron Scott Dyer [HPN/NY]   09/20/08 01:33 AM
. * * Re: Turbine P-Baron Robert Mann [HPN-NY]   09/19/08 09:37 PM
. * * Re: Turbine P-Baron Dave Siciliano (ADS)   09/19/08 10:51 PM
. * * Re: Turbine P-Baron Robert Mann [HPN-NY]   09/20/08 03:25 AM
. * * Re: Turbine P-Baron Jeff Hartmann CIC   09/19/08 09:14 PM
. * * Re: Turbine P-Baron Scott Dyer [HPN/NY]   09/19/08 09:37 PM
. * * Re: Turbine P-Baron Robert Mann [HPN-NY]   09/19/08 08:55 PM
. * * Re: Turbine P-Baron Dave Siciliano (ADS)   09/19/08 09:15 PM
. * * Re: Turbine P-Baron Rick Durden   09/19/08 08:47 PM
. * * Re: Turbine P-Baron Dave Siciliano (ADS)   09/19/08 09:15 PM
. * * Re: Turbine P-Baron Robert Mann [HPN-NY]   09/20/08 02:55 AM
. * * Re: Turbine P-Baron Dave Siciliano (ADS)   09/20/08 03:45 AM
. * * Re: Turbine P-Baron Dave Siciliano (ADS)   09/20/08 04:24 PM
. * * Re: Turbine P-Baron Robert Mann [HPN-NY]   09/20/08 04:45 PM
. * * Re: Turbine P-Baron Dave Siciliano (ADS)   09/20/08 05:50 PM
. * * Re: Turbine P-Baron Mase Taylor   09/20/08 06:09 PM
. * * Re: Turbine P-Baron Dave Siciliano (ADS)   09/20/08 07:42 PM
. * * Re: Turbine P-Baron Rick Durden   06/15/08 03:23 PM
. * * Re: Turbine P-Baron Dave Siciliano (ADS)   06/15/08 04:53 PM
. * * Re: Turbine P-Baron Dave Siciliano (ADS)   06/15/08 04:55 PM
. * * Re: Turbine P-Baron Tony Williams [MYF]   06/15/08 05:19 AM
. * * Re: Turbine P-Baron Dave Siciliano (ADS)   06/15/08 01:51 PM

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