Serious simulators: X-plane and 747-400 precision simulator

Flight Journal, Oct 1999 by Lert, Peter

Desktop computer-flight simulation packages continue to proliferate in almost bewildering variety. As I've mentioned before, they range from airborne "first-person shooters" through reasonably good mass-market flightsimulation products such as Microsoft Flight Simulator and Pro Pilot to the recently released FLY! to very pricey dedicated instrument-flying trainers such as Elite and On Top. The latter two products are so good that the FAA accepts their use for up to 10 hours of required instrument training for a pilot's license. Unfortunately, many of these software packages are in the $300and-up class, while the additional hardware required to qualify them as FAAaccepted personal-computer aviationtraining devices ("PCATDs") can add thousands more.

There are, however, a couple of remarkable products that defy any attempt to be categorized (or, more accurately, that have established unique niches of their own). One is X-plane from Laminar Research; the other is 747-400 Precision Simulator from Aerowinx. Each has engendered a worldwide user community; each is heavily supported on the Web. Considering their capabilities, each is a very good deal at $199. Furthermore, at press time, the newest version of X-plane had been temporarily discounted to an astonishing $129.

In this era of over-hyped software products developed and released (usually late) by big, heavily financed teams of programmers, these two programs are almost unique in that each is the work-perhaps the lifework!-of a single individual.

X-plane, or, "Austin MeyersInternational Man of Mystery"

X-plane has been called many things. The epithet "ultimate desktop flight simulator" is hardly exaggerated. "Stealth simulator" might be another good description, since the program is hardly known at all outside its large and wildly enthusiastic user community; as far as I know, it's not advertised anywhere except on the Internet.

Go to www.x-plane.com, however, and you'll find yourself on the threshold of a flight-simulation experience that I've only begun to explore after hours of fascinating experimentation. X-plane developer Austin Meyers modestly states on the opening screen that "X-plane is the world's most comprehensive flight simulator and the most realistic flight simulator available for personal computers." Thus far, I've found no reason to refute his claim.

Let me look at these two assertions separately. In terms of "most comprehensive," it's not just that 30-odd aircraft, ranging from homebuilts to helicopters to the X-15, are shipped with the current version 5.0 of X-plane (although as far as I know, that's more than you'll get as standard with any other product); rather, it's that the X-plane package includes an additional application called "PlaneMaker" that allows even a newbie to input the design parameters of any existing (or imagined) aircraft with a minimum of effort or technical expertise. Earlier versions of Xplane displayed aircraft as rather blocky polygons, but more recent ones (that require the hottest razzle-dazzle graphics cards) render them beautifully in 3D. In fact, if you have a bitmap of your favorite paint scheme or airline livery, PlaneMaker will accept that, too. Needless to say, since X-plane has been around for a few years, there's a plethora of related websites (all linked through the x-plane.com site) that offers hundreds of aircraft developed by users around the world. The current version of the system also includes a utility to update aircraft developed for earlier releases.

PlaneMaker works equally well, of course, with airplanes that presently exist only in your imagination-as long as you've written down some basic design information. A sub-module, PartMaker, allows you to input such factors as size and location of control surfaces and the performance characteristics of the airfoils used on your aircraft's wings (or, if applicable, props or rotor blades). In fact, the system's flexibility and accuracy allow it to be used to explore not only the performance but also the flying qualities of both existing and imaginary airplanes. It's not just a flight simulator; it's also a sophisticated aeronautical-engineering tool. To aid this application, the system includes a "black box" mode that allows you to store, download and analyze any of the parameters used or calculated by the flight model.

This leads right to Austin's second assertion: "... the most realistic flight simulator available for personal computers." Most mass-market flight simulators use relatively simple flight models that are often a compromise between the various aircraft modeled, sometimes corrected only for size and mass. I can think of at least one such product in which a business jet flies "just like a Cessna 172, except it reacts slower and the performance numbers are different." By contrast, X-plane uses a flight model "engine" that's just as sophisticated as those used by the big aircraft companies. While Austin keeps some of the details proprietary, his disquisition in the X-plane manual on how his flight model works reveals that he used such techniques as finite element analysis, multipart velocity determination and coefficient calculations, including the classic "Prandtl-Glauert rule" as well as Mach-number factors to build up all the forces on the airplane; and that's even before he gets down to the basic Newtonian calculations of what those forces are going to do to the aircraft. As he says in the manual, "... now do the whole thing over again at least 15 times per second. Aren't computers great? Now that you know, we have to kill you ...." The included bibliography suggests that as well as being one hell of a programmer, Austin has gone out and gotten himself a very thorough grounding in aerodynamics. I might add that the model is so sophisticated that it works equally well when dealing with the wild and wacky aerodynamics of rotarywing aircraft, including the V-22 Osprey tilt-rotor as well as a whole bunch of helicopters. Want a real challenge? Try landing one of the helos on the deck of X-plane's Navy frigate with the weather set nasty enough to provide big seas and a nice pitch and roll to the landing deck!