J-3 Cub Lua Script Vessel Add-on for OpenOrbiter 4

Some major improvements to this add-on.

• Implemented Otto cycle model for reciprocating engine performance. Matches power and fuel consumption of an A-65 engine very well. Inputs are engine displacement volume (in cubic meters) and compression ratio.
• Implemented a momentum disk model of the propeller which translates the calculated engine power to thrust. A root finding routine solves for the air velocity exiting the propeller at a given power, which provides the thrust applied to the vessel. Delivers very appropriate levels of thrust at all flight speeds and power levels.
• A dihedral model that provides a righting moment to level the aircraft.
• Sundry improvements to aerodynamic model.

Improvements in this version:

1. Updated with mesh shifted to put CG in center of literature range for J-3
2. Improved lift and moment coefficients for USA 35B airfoil from NACA TN 219

These changes generally reduce the magnitude of elevator trim changes to maintain level flight as airspeed changes and eliminates falling-leaf hunting of angle of attack.

Considering updating the propeller mesh to improve its look and reduce poly count. Also considering 3D bouncy tires for bush flying. Stay tuned...

This is an updated version of the script. The Lua methods used for these scripts were implemented in OpenOrbiter very recently and one important one, oapi.load_mesh_global, was quickly replaced with oapi.load_meshglobal sometime in March or April it seems to match the C++ version of that method. I developed the script using the version that supports load_mesh_global, but many with newer versions of OpenOrbiter cannot read the mesh file. I have updated that method to the newer form which should remedy that problem.