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raymar

CJ2 v1.1 performance is near book perfect - FL450 400kts 672 lb/hr

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Yep, I think we finally have a high performance Citation with HD textures inside and out.

 

This is using the recent Carenado v1.1 CJ2 with a minimal tweak of an additional 2% thrust scalar so I could use the CJ2+ detailed performance charts. I will rerun the same test with a plain vanilla scalar - no changes - to compare the results.

 

UPDATE: Same flight test with no changes to scalar - Pure v1.1 FL450 389 kts, 643 lb/hr ISA -56C, all else same.

 

This is really good news to those that have been waiting for a small Citation with solid performance. No more eye candy here - this one is ready to go to work for the Virtual Airlines.

 

I am using most of our latest community mods to show the captured performance numbers. The Flight Info box tells the full story.

 

FL450 ISA temp -56 deg C Takeoff with full fuel, step climbs at FL290, FL350, FL410 just to check speeds and fuel flow. Steps climbs are not required in the CJ2.

 

 

Full details can be posted if requested.

 

Just imagine, we now have a modern corporate jet with HD textures that cruises 400 kts at FL450 with 4+ hours of cruise time remaining. Looks great, flies even better, and book performance.

 

Our community mods enhance the single pilot flight sim experience. Almost no head down time required. Clickspots and popups galore.

 

Best Regards,

 

Summary here:

400 kt at FL450_1024.JPG

CJ2+  400 kt FL450 chart_a.jpg

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The step climb info is:

 

14:02 min to FL290 423 kts TAS, 1317 lb/hr Fuel Flow

FL350 413 kts TAS, 1017 lb/hr FF

FL410 406 kts TAS, 787 lb/hr FF

 

Regards,

 

Ray

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Ray what did you adjust the Thrust Scalar to??

 

NM just re-read your post, brain not working.........

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Hi Ray,

 

Look'n good - the only issue I see - if I understand it correctly - is that you are at 102.4% N1 and the chart says 94.8% ??? We knew N1 was off though... From my limited testing - I found the default pretty close to the charts as well - when running at 102.4%... If I get some time - I may load this FDE up in Air Wrench and take a look around (I'm no expert though) - as I'm curious...

 

Regards,
Scott

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Hi Ray,

 

Look'n good - the only issue I see - if I understand it correctly - is that you are at 102.4% N1 and the chart says 94.8% ??? We knew N1 was off though... From my limited testing - I found the default pretty close to the charts as well - when running at 102.4%... If I get some time - I may load this FDE up in Air Wrench and take a look around (I'm no expert though) - as I'm curious...

 

Regards,

Scott

Scott,

 

Because we do not have the detailed cruise charts like the CJ2+ for our CJ2, I bumped up the scalar to match the CJ2+ thrust (needed an additional 2% to go from 2400 to 2490 static thrust).

 

It turns out that is not a good idea because we don't know how the FADEC in the CJ2+ is managing the engines and the two planes have different engines, not just slightly different thrust levels.

 

Our CJ2 Williams-Rolls engines are designed for Wide Open Throttle applications (WOT) or let's just call it FULL THRUST for high speed cruise performance. If you can get the full 100% (102.4% N1 RPM) then that is the goal.

 

In effect, you could simply replace the FAN % RPM column that I used with the (1) footnote - MAXIMUM CRUISE THRUST and be safe.

 

For an unlimited climb to high level cruise, I use FULL THRUST and maintain a climb rate/speed that avoids overspeed.

 

Until we find something better to use, I suggest using the CJ2 Flight Planning Guide charts along with the Carenado provided data in the docs folder. All this has is a Gross Weight of the A/C, Flight Levels every 2,000 feet, and KTAS with the associated lb/hr total fuel burn for both engines.

 

I am going to keep the thrust scalar at the v1.1 level to avoid confusing the community and then everyone should be on the same page when comparing performance results - which appear to be outstanding.

 

I am attaching the High Speed Cruise table from the CJ2 FPG for those that may not have it.

 

Regards,

 

Ray

FPG High Cruise.jpg

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Seems like the speeds are near perfect for both High Speed Cruise and Long Range Cruise. The Fuel Flows are not as close, but are acceptable.

 

I found at full throttle (book recommended) Fast Cruise the speeds are really, really close to book, but, the Fuel Flows are about 8 - 9 % lower than book.

 

At Long Range cruise settings (typically Mach .58 - .60) the Fuel Flows are a lot closer to book.

 

I adjusted the Fuel Flow Scalar from 1.75 to 1.85 (ran tests at 1.80 also)and found that to be the best balance between the two.

 

Direct climb to the upper Flight Levels is a really enjoyable after flying the S550 S/II.

 

I am recording the flight data and making an Excel chart to view the results. I am also snapping a screen shot of the FLT INFO box window at each recording point - boy what a nifty feature this has turned out to be.

 

Bottom line. Good Strong performance and plenty close enough to book to enjoy.

 

Regards,

 

Ray

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Hi Ray,

 

Look'n good - the only issue I see - if I understand it correctly - is that you are at 102.4% N1 and the chart says 94.8% ??? We knew N1 was off though... From my limited testing - I found the default pretty close to the charts as well - when running at 102.4%... If I get some time - I may load this FDE up in Air Wrench and take a look around (I'm no expert though) - as I'm curious...

 

Regards,

Scott

Hello Scott,

 

I now have the official AFM Performance charts for the CJ2. Just as I suspected the full thrust 102.4% rpm is called out for fast cruise. I reran all my speed and FF tests from FL270 - FL450 for high cruise and a few cases for Long Range Cruise. The base v1.1 is near spot on for Speed and no more than about 5% low for Fuel Flow. Plenty close enough for most folks.

 

Take a look at this FL390 page.

 

Regards,

 

Ray

FL390 example.JPG

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Hi Ray,

 

Great stuff !!! I do like being fairly realistic...

 

That means our flight planning should be close - close enough for me anyway...

:wink:

 

Regards,

Scott

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Guys

 

I read this thread with interest but I think I have missed something.  There is talk here of having N1 readings of 100%+ but I can't get anything above 98%.  Is there something I need to do to achieve those higher N1 readings?

 

Regards

 

Jim Mclean

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Guys

 

I read this thread with interest but I think I have missed something.  There is talk here of having N1 readings of 100%+ but I can't get anything above 98%.  Is there something I need to do to achieve those higher N1 readings?

 

Regards

 

Jim Mclean

I had to calibrate my Saitek throttle. Using FSUIPC it was easy peasy. Yes, the Williams-Rolls Engines in the CJ2 are designed to spin at 102.4% at altitude - no limit.

 

Regards,

Ray

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