I have been working on version 4.5 of my flight physics & simulation system. Sim border handoff behavior seems to be a little better these days and I've heard there will soon be a release that will optimize sim handoffs a little bit.

Here is a preview of what I'm working on:

• Almost every prim in the chassis is sculpted. This allows me to save a few prims, which in turn lets me do things like adding more detail and moving control surfaces.
  
• All scripts have been switched over to the new, exponentially faster Mono scripting engine.
• Physics engine runs at 20FPS instead of 4 (although it will run slower if the sim is busy.)
• Several scripts have been merged, in order to take advantage of the much higher memory limits now available.
• Physics system has far better granularity. Allows handling different power/lift configurations much more easily, so there isn't a ton of customized code in each different model of airplane. Less custom code = easier to port upgrades to older models, and less fiddling about to get new models up and running.
• Support for version 2 of my Reentrant Integration Physics (RIP) system. One of the planned aircraft is an autogyro, and RIP will be used for the rotary wing. RIP version 1 was used in the Cygnus autogyro. Version 2 will be lots more accurate, partially because I've spent more time messing with autogyros in X-Plane. I'd love to get some time in a real one, but no one around here has one.
  
• Many scripts have been removed from moving parts & their function has been migrated to other scripts, taking advantage of llSetLinkPrimitiveParams().
• Large reduction in number of scripts has made border crossing more reliable.
• System added to assist border crossing; it is somewhat aggressive but increases survivability at high speeds. It can be on, off, or auto (active above a set airspeed.) Even with three avatars in the airplane, I've experienced few problems in testing, except in sims that were having trouble. And that's doing 160 knots. Good luck surviving anything over 60 knots without this system!
  
• Travel at high speed is marginally smoother.
• Bug affecting power-off glide after engine stoppage squashed.
• Aerodynamics tuned to be a little more realistic. (I keep flying more different airplanes in the real world, and I learn a little something new with each one.)
• A couple bugs in the Nav-Tac HUD have been squashed.
• Probably more stuff I've forgotten about.