Asobo Cessna Citation Model 700 Longitude Performance and Flight Dynamics Modifications Project Version 1.82
Featuring Optional OnAir Virtual Airline Compatible Installation Package

Please check out the chatter and follow the progress of this project on the offical MSFS 2020 Forum:
https://forums.flightsimulator.com/t/cessna-citation-longitude-flight-dynamics-modification-project

Version 1.82 Changes:

• Fixes an Asobo bug in the panel configuration files borrowed from the Aviator's Livery (used to address the gear warning and to implement the altitude call-outs) that was causing users of version 1.81b, who after having reinstalled the default Longitude and installing 1.81b, to no longer be able to see the external / tail registration number for the Longitude, or for any Longitude third party Liveries. If you are not having issues with your prior version of the Longitude mod, through version 1.81, you don't need this update, but this fix will be carried forward into future updates to ensure stability and to avoid this bug recurring.

Version 1.81b Changes:

• Should resolve the issue for those who have had problems with installation of 1.81 with the Longitude no longer showing up in the aircraft selection menu. There are no changes other than updating the layout.json file. If you have not experienced issues with this, there is no need to download and install this version. If you have problems seeing the Longitude or have CTD issues after installing 1.81b, try removing the mod, then delete the default Longitude from within the sim using the content manager, then reinstall the default longitude using the content manager, then reinstall the mod as instructed. 

Version 1.81 Changes:

•  Reverts flaps lift coefficient back to prior values in response to Asobo's March 02, 2021 hotfix correcting Asobo's UK update error. This update will restore proper take-off, approach, and landing speeds after the Asobo hotfix.

Version 1.80 Changes:

• Significant changes to engine parameters to achieve improved, "on the numbers", climb performance at various aircraft weights. Aircraft should follow Cessna spec climb profiles (300 IAS to intercept Mach 0.8 - 457 to 460 KIAS for high speed climb, for example). The aircraft should be able to intercept M0.8 and hold this speed for a climb of approx. 23 minutes to FL430 at MTOW and 16 minutes to FL430 at a takeoff weight of 33k lbs. Climb profile used in Cessna's testing for high speed climb is 290 KIAS to 10k feet (unrestricted climb), 300 KIAS to intercept with M0.8 (at approx. FL300) and hold M0.8 to cruise altitude.   
• Adjusted engine thrust output as a function of N1 to bring this much closer to real world published N1 / performance results. The range of N1 values needed to maintain specific airspeeds, in particular at cruise, is quite narrow. This update improves performance to replicate this more narrow band of N1 vs thrust performance. 
• Adjusted PID values for autothrottle to improve speed capture and hold speeds in general and with narrower N1 / thrust banding. There will be more/faster throttle lever movements and adjustments, especially at lower altitudes and airspeeds. This is somewhat experimental at this time.   
• Adjusted aircraft lift paramaters to bring aircraft closer to real world V-speeds.
• Further adjustments to stall speed boundaries and aoa limits. However, achieving realistic stall performance at the manufacturer tested speeds has not been possible without disrupting other significant aspects of aicraft performance - the sim doesn't read all values in the lift coeffiecient aoa table entries which makes this effort somewhat limited.
• Slightly increased elevator authority to increase pitch control, especially at lower speeds like during takeoff and approach. 
• Corrected flaps lift coefficient after Asobo update from Feb. 16, 2021. 
• Corrected missing altitude alert callouts in OnAir version.

Please see version notes in the included install_readme file for a list of all changes made since project inception and a list of open items / known issues.

Installation:

• Download the .zip file and extract to desktop or other location of choice.
• Please read and follow the installation instructions in the included Install_ReadmeV1.81.txt file carefully.

Installation Note:
To confirm correct installation, when in the livery selection menu for the Longitude in MSFS2020, the default Asobo Longitude livery will display the following in the variant area "FDE Fix V1.82" or "FDE Fix V1.82 OnAir" depending on the install version you choose. This will help you quickly identify whether installation of the package was successful and identify package version - this will only affect the default Asobo livery listing and not other liveries, however the performance modifications will be applied to all livery versions.

The Cessna Citation Model 700 Longitude Performance and Flight Dynamics Modifications Project:
After reading user comments on the forums regarding the Cessna Citation Longitude model from Asobo concerning major autopilot problems, inaccurate weights, fuel load, fuel consumption, handling, etc... and due to my own poor experience and frustration with Asobo's starting efforts, I started work on revising a wide variety of parameters in the configuration files borrowed from the Cessna CJ4 model to match the specifications for the Longitude. I modified the default layout.json file for the Longitude to bypass the encrypted configuration files and point to copied versions of non-encrypted files from the CJ4. These files have all been heavily modified and with a fair amount of guesswork I've been able to produce a working version of the Longitude that is more docile in handling and produces performance numbers that much more closely match the real-world specs. I'm not a Longitude pilot, so my modifications are based on comments on forum topics from those who fly the type, and generous contributions of real world C700 aircraft performance charts, flight manuals, and checklists from fellow flight-sim enthusiasts who also fly IRL for a living. Input from type-rated pilots with knowledge of the aircraft handling and envelope will always be greatly valued.

NOTE: My adjustments are generally focused on performance and handling. Any issues with the G5000 suite and avionics in general are not the subject of this modification. If Asobo chooses to decrypt the xml files associated with the type, a motivated person could presumably start modifying and improving the avionics suite much like has been done with the CJ4 and other un-encrypted aircraft.

I have modified a great many variables and parameters in the available configuration files. I would greatly appreciate feedback on handling, control sensitivies, or other performance related parameters from knowledgable sources so I can continue to improve and update these modifications. If I missed something or you find a performance "glitch" please let me know.

Contribution credit and acknowledgements can be found in the Install_ReadmeVX.XX file included.