At this site you will find information and some add-ons (added later) for YS Flight  
Update 4 August 2016 - New tools are available listed at YSFlight Wiki


YS Flight Simulator is a flight simulator program written by Soji Yamakawa. It can be downloaded at www.ysflight.com. The simulator lacks high end graphics and  textures (although ground textures are said to be incorporated in the latest version) It has an impressive range of features : multi - aircraft air combat simulation with guns  and missiles, ground attack missions, anti-aircraft fire from the ground, network playing,  a recorder
 to play back flights, and rudimentary navigation and an autopilot.

Tutorial for creating aircraft

This tutorial is about an easier way to create aircraft for YS Flight than creating the aircraft point by point. I have created two aircraft already for YS Flight