This article is about a flight simulator. For experimental aircraft, see X-plane.

X-Plane, produced by Laminar Research, is a flight simulator for personal computers, notable for its high degree of sophistication and customizability.

Unlike other simulators, which use precalculated tables of data, which they refer to and tweak according to atmospheric conditions etc., X-Plane incorporates blade element theory, a technique developed to analyse propellor behaviour. It involves breaking an airfoil down into several pieces, and then by reference to its velocity, calculating the forces exerted on it. X-Plane applies this to the entire aircraft, treating the fuselage, wings, tail and control surfaces as slowly-rotating propellors. The advantage of this over 'traditional' flight simulators is that, in theory, no performance data need ever be gathered from the real aircraft - all you have to do is enter the craft's geometry, mass, engine position and power, and X-Plane models the performance all by itself.

X-Plane has even been used as an aid in designing concept aircraft, such as the Carter Copter, and a look around the Registry at X-Plane.org will reveal hundreds of completely imaginary aircraft made by people ranging from aerospace engineers, to school children.

One of the greatest accolades that X-Plane has is that it is fully certified by the American FAA for flight training. But don't think you'll get your pilot's licence on your desktop; hours are only valid when taken in a full motion simulator, run by four copies of X-Plane tied together. Nonethless, as the X-Plane website gleefully points out, Microsoft Flight Simulator is under the games section of Microsoft.com - X-Plane is good enough to be used as the real thing.

X-Plane was largely developed using the Apple Macintosh computer with Mac OS X, but is cross-compiled to the Windows operating system as well and should, although it is not recommended, run on Mac OS 9. Also available is a Linux version, although as it is being tweaked and compiled by a different programmer (who is only fifteen), the Linux releases tend to be later than the Mac and Windows versions. The 3D graphics are fully based on the cross-platform OpenGL libraries.

X-Plane 8, the newest version of the simulator, has significant improvements in aircraft design and, most importantly, scenery graphics. Instead of the 'chessboard' style terrain mapping used in version seven, where lines had to run in set directions, version eight now has a new system which allows totally irregular polygons to be created. The code is also actually more efficient, so doublings of frame rates from version seven using 'generation seven' scenery have been reported. On the other hand, the new 'generation eight' scenery is far more detailed - it actually has the capability to place buildings and roads according to actual street maps and this obviously impacts on the frame rate. Unfortunately, the new scenery also uses display lists - a method of pre-loading scenery for rapid output - and, although this works fine with Windows, Macs - always a key market for X-Plane - seem to have trouble with them - they use more RAM per display list, and hence spend more time trying to retrieve them. The solution that X-Plane's creator Austin Meyer has decided upon is quite simple: write new display list managers for the Mac version, replacing the ineffectual ones. Although, due to publishing pressures, X-Plane has already gone final without the new display list managers, much work is being done on them - often in partnership with Apple, and they should be available in a version to come.

External link

• X-Plane homepage
• X-Plane.org Download heaps of planes; has an extensive webboard; an invaluable community resource!
• category at ODP