Chassis Types 
- Year of introduction: 2004
- Meaning: A low-pressure area immediately to the side of and behind an object moving through the air. If you've ever been in a car on the freeway and felt a slight push as you drove past a big rig, you were crossing the threshold of its slipstream. The term "A-11" is meant to imply that the jet was designed after, and to evoke the image of, the Fairchild-Republic A-10 Warthog II.
- Role: Amphibious, small, extremely maneuverable, extremely fast personal jet
- Chassis description: Small, no cockpit. Front canard, stubby wings, and twin vertical stabilizers after the fashion of an A-10 Thunderbolt II.
- Engine: Chassis has a supercharging intake and rectangular exhaust, and supports a small engine mounted in the fuselage.
- Seating: 1+1 (pilot and passenger)
- Models: A-11 Slipstream II
- Historical note: The SSII holds the current SL airspeed record at about Mach 0.51.
- Year of introduction: 2005
- Meaning: Anserinae, the subfamily of waterfowl geese are identified with. Geese are graceful both in the water and in the air, but they can be extremely aggressive when provoked! That isn't to say that aircraft built on the Anser platform are "mean" - the aggressive part is really the speed.
- Role: Amphibious ultralight personal aircraft. Both fixed- and rotary-wing aircraft have been built on this platform.
- Chassis description: Spherical cockpit, tapering conical tail section. Fixed landing gear. Engine can be mounted in various configurations.
- Engine: Usually a single VHI-T5-RH or variant, either built into a superstructure or mounted on a pylon.
- Seating: Usually pilot-only, but there is no hard restriction about passengers.
- Models: G-1 Cygnus autogyro, U-1 Skylark
- Year of introduction: None; this is a testbed for the time being
- Meaning: Calm, peaceful, prosperous times.
- Role: Amphibious multirole jet with VTOL and extended hovering capabilities. Can be used for peaceful exploration, but capable of carrying ordnance. The "R" in R-1 Halcyon stands for Recon.
- Chassis description: Forward cockpit terminating in a "bottlenose" shape. Fuselage mostly resembles a U.S. F-1x series fighter, except that there is a very stout, bulbous section just aft of the cockpit. This contains the lift jet.
- Powerplant: Twin high-output engines (forward thrust) and one high-output lift jet (VTOL, hover).
- Seating: Pilot only
- Wings: Variable geometry
- Ordnance: GAU-8/A cannon in development, others TBD
- Models: R-1 Halcyon
 Accipiter
- Year of introduction: 2006
- Successor to the Halcyon
- Meaning: Members of family Accipitridae (birds of prey, particularly goshawks and sparrowhawks)
- Role: Amphibious multirole jet with VTOL and extended hovering capabilities. Can be used for peaceful exploration, but capable of carrying ordnance. The "R" in R-5 Accipiter stands for Recon.
- Chassis description: Forward cockpit terminating in cone. Fuselage mostly resembles a U.S. F-1x series fighter, except that there is a very stout, bulbous section just aft of the cockpit. This contains the lift jet.
- Powerplant: Twin high-output engines (forward thrust) and one high-output lift jet (VTOL, hover).
- Seating: Pilot and co-pilot
- Wings: Variable geometry
- Ordnance: Terra Combat System, Callahan Combat Control (pending a fix from the CCC folks)
- Models: R-5 Accipiter
 Nimbus
- Year of introduction: 2007
- Meaning: A variety of cloud
- Role: Amphibious fixed wing jet.
- Chassis description: Forward cockpit terminating in cone. Fuselage reminiscent of various general aviation aircraft.
- Powerplant: Twin VHI-T105-RH
F-16
- Year of introduction: 2007
- Role: Fast attack jet.
- Chassis description: Highly detailed, attachment-based, developed from 3-views of the F-16.
- Powerplant: Single F00-PW-200
 Sculpted Amphibious Hull - Year of introduction: 2009
- Role: Avocet Seaplane & Exocet Autogyro
- Chassis description: Seaplane hull with provisions for repositionable gear. Low wing design inspired by Beriev 103 seaplane. Tailplane and dual vertical stabilizers connected to fuselage with twin booms in order to allow lower mounting of engine & propeller.
- Engine is mounted in pusher configuration with above centerline thrust. Intake is mounted as high as possible to avoid sucking in water on bad water landings.
Engine Types - Role: Ultra-small jets
- Twin-screw intake charge pre-compressor
- Afterburner manifold
- Used in: A-11 Slipstream II
- Role: Heavy-duty powerplant for recon/attack jets
- Used in: R-1 Halcyon
- Role: Ultralight jets
- N1 turbine: 8-stage axial
- N2 turbine: 3-stage axial
- Afterburner (the RH stands for reheater)
- Used in U-1 Skylark ultralight
- More powerful derivative used in G-1 Cygnus autogyro
- Can be connected to a driveshaft to run a transmission, as in the Cygnus, which is VTOL capable
- Role: Heavy-duty powerplant for recon/attack jets
- Used in: R-5 Accipiter
- Role: Fast-start, high-output lift engine
- Based on VHI-T5-RH
- N1 turbine: 10-stage axial
- N2 turbine: 3-stage axial
- Afterburner (the RH stands for reheater)
- R-5 Halcyon & R-1 Accipiter use this for their lift engines
- Role: Powerplant for small jets
- Scaled down version of the VHI-T107-RH
- Used in: V-1 Nimbus
- Role: Propeller driven aircraft
- 550 cubic inches (9.01 liters) of displacement
- Six cylinders, horizontally opposed ("boxer")
- Direct fuel injection (GDI) with lean-of-peak operation
- Idle fuel flow 1.8GPH
- Full throttle fuel flow 10.2GPH
- Full throttle + turbocharger fuel flow 25.8GPH (if equipped)
- Constant speed prop, manifold pressure (throttle), and mixture are on a full-authority digital engine control (FADEC) connected to a single power lever
- VHI IO-550-TC model is turbocharged. Bypass is open at all throttle settings up to 100%. At 110%, the bypass closes & the turbo engages. Fuel consumption below this point is the same as naturally aspirated. Maximum power and engine torque are both increased by about 35% with the turbocharger engaged. With 550 cubic inches pushing the hot section, this turbocharger spools up very quickly!
- Archduke 5-5 is equipped with two normally aspirated IO-550s. Avocet and Exocet use one turbocharged IO-550-TC.
- Newer versions have hydrolock protection. They will shut down if the vehicle breaches the surface of the water by more than one meter.
- Based on the Pratt & Whitney model of the same name
- Used in the F-16
- Significantly derated vs. the real life model since a supersonic aircraft would be quite lethal to the pilot in Second Life
- Sounds exactly the same and has an afterburner
- Particle accelerator used in the VIIPS jetpack
- Four distinct thrust levels
Valen Vehicle Dynamics Engines
- Developed 2003-2004
- Initial release: Slipstream, 2/2004
- Physics enhancements: Afterburner
- Smooth controls
- Vehicle status checks
- Head-up display
- Second release: Slipstream II, 4/2004
- Physics enhancements: Lift and stall forces, somewhat smoother afterburner
- Stall horn and glidepath system
- Some minor control refinements
- Afterburner now variable, and with better spoolup/spooldown simulation
- Developed 2004-2005
- Currently used in the R-1 Halcyon prototype
- Physics enhancements: Better stalling behavior, engine efficiency calculations, better acceleration calculations, smoother afterburner (which was backported to the Slipstream), etc
- Multimode operation support added (for example, forward flight vs. VTOL)
- Preliminary (i.e. somewhat working) support for mouselook control, including some interesting trig
- Some other features related to the operation of jet aircraft
- The U-1 Skylark ultralight is based on Halcyon (VVDE II) code, but is intended to be much simpler than the Halcyon; parts of the Halcyon codebase that didn't make sense in an ultralight are not present in the Skylark
- Developed in August 2005
- Formerly deployed in the G-1 Cygnus autogyro, which has since been replaced by the Cygnus II
- Significant further refinements to the VVDE II engine
- Throttle now increments/decrements repeatedly if you hold down PageUp/PageDown
- Autogyro-specific physics and voice controls added
- Inherits stall horn system from Slipstream and Halcyon
- Cygnus II autogyro gets further updates to this engine for significantly better rotor and other airfoil simulation
- Reentrant Integration Physics
- Extension to VVDE II+
- Currently deployed in the G-1 Cygnus II Gyrocopter
- Uses reentrant (not quite recursive) signaling between independent processes, propagating and integrating physical information over time rather than instantaneously
- Inspired by studying the operation of neurons
- Some realistic behaviors (and interactions between behaviors) tend to emerge from this system on their own, rather than having to be specifically coded; others still have to be coded, but are greatly simplified (and naturally less "arthritic" as the system increases in complexity)
- VVDE III's vehicle physics code is based loosely on the X-Plane physics model, which is described here (I don't use blade element theory)
- VVDE III attempts to calculate aircraft physics up to 4 times per second
- Ideally physics are calculated 20 or more times a second, but LSL runs very slowly, so this is not currently practical
- Throttle, pitch, roll, and yaw are ramped, rather than changed instantaneously, for a much more realistic feel than the "stepped" behavior of the stock vehicle system
- Available engine thrust is factored into the actual thrust generated, so thrust is not fully available until engines are actually finished starting up
- Engines take time to spool up and down, rather than instantaneously jumping between thrust levels
- Lift is calculated, although it is damped above a certain point in order to eliminate the necessity of adding trim controls
- Drag is calculated based on lift, airspeed, air density, and front cross sections that have been precalculated for forward-facing surfaces
- Gravitational effects on the aircraft are calculated and affect velocity (particularly at high pitch angles) and cause the aircraft to drop if it is below stall speed
- Inertial effects, such as speed loss on sharp maneuvering, are calculated
- "Emergent" effects, such as stall, tip stall, and ground effect are calculated
- Control surface effectiveness is calculated
- Sum of rotational force is handled by the vehicle system
- Sum of linear force (up to 40 m/sec on each axis) is handled by the vehicle system
- The remaining linear force (anything above 40 m/sec) is handled separately, meaning that the aircraft can travel much faster than the 40 m/sec afforded by the stock vehicle system
- Certain effects are "smoothed" against recent values, in order to avoid computational flutter, although it can still get nasty in sims with poor script execution
- Low Realism disables some of these effects, particularly those that might be challenging for a new pilot, and those that could become hazardous and unpredictable while flying through sims that have poor script execution
- VVDE III had a monolithic (single-threaded) physics engine
- This was split into two threads for better performance and improved control response in situations where scripts are running slowly
- Some processes try to run at 4FPS (particularly where they need to stay in sync with other threads), others run faster
- Aircraft systems support architecture put into place for handling things like fuel consumption
- VHI Nav-Tac HUD reworked to support systems architecture, and given a multi-page MFD
- Further refinements made to physics modeling
- "Skins" system put into place, enabling airframes to bear multiple skins (this is used in the Nimbus)
- Support for tricolor AOA gauge, originally implemented in the F-16 and then implemented in the Nav-Tac HUD
VVDE 4.5
- First implementation of VHI X-Guard, which momentarily turns the vehicle physics off during sim crossing (original idea by Francis Chung)
- X-Guard turns on above 40 knots to help prevent the usual way SL spazzes out on sim border crossing - it's off below 40 knots. It can also be completely turned off, or forced to run at all speeds. In automatic mode it will activate even below 40 knots if it detects that the scripts are running slowly (which would indicate bad sim performance.)
- X-Guard crosses more slowly the more avatars you are carrying.
- Several control system & physics refinements
- Support for Reentrant Integration Physics version 2 (used in autogyros)
- Various code cleanups
- Several scripts were merged to take advantage of the higher memory limit now available
- A bunch of control surface scripts were removed & had their functionality implemented in other scripts to cut down on the number of total scripts
- Guest/copilot support is a bit better developed. Control can be given and taken at will during use, and you can get out of the aircraft after you give control to a friend & let them fly it without you. At this time, dual control is still not available due to this bug. (Please log in at the JIRA and vote for it!)
- A bug affecting power off glide & other physical behaviors after engine stoppage was found & squashed
- Reverse thrust up to 20% is allowed to assist in slowing descent during a steep approach to landing
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VHI Technical