Written by Daniel Dubreuil (dany93), May 2016, with what I currently know.
Feel free to amend it.

About 2003: P51D Creation by Jim Wilson, with a YASim FDM.

Around from 2010: Hal Van Engel improvements.
Implementation (in collaboration with Jon S. Berndt) of the JSBSim FDM.
During 2010 - 2014, Hal Van Engel made this aircraft one of the most wonderful, sophisticated in FlightGear:
- FDM, stall and spin behavior (pionneer work, up to flat spin).
- Systems
- 3D
..... ?

Viewed from the FlightGear community, this aircraft was his "kid".

Hal, we miss you very much...

2015 - 2016:
Autostart implementation by githlar.
Some minor FDM modifications by Daniel Dubreuil.
Wheel spin animations,
Cockpit: fix Throttle, Mixture, Propeller pitch controls by mouse,
Checklists: fix marker locations by Daniel Dubreuil

2017 - 2018:
Significant improvements to the 3D model from Denk Padje (onox), particularly
improving the external model.
