Posted by Florian Wardell | 9 comments
Interview with X-Plane creator Austin Meyer
Austin Meyer is a busy man. His sentences rarely go beyond five words, he never uses punctuation and seems to have developed a particular relationship with his caps lock key. But Austin Meyer is a living legend in the simulation community. After all, he spent the last decade competing with Microsoft’s longest-running franchise, Flight Simulator. His creation, X-Plane, is now the only major sim currently under development - last year, the ACES studio, responsible for Microsoft’s product, filed for chapter 11 and left the flight simulation scene. Now that he remains the sole player in a game that used to be driven by competition, Austin focuses on fine tuning X-Plane, on targeting other platforms and preparing the next major release – X-Plane 10 – which is set to burry Microsoft’s Flight Simulator once and for all.
TechHaze: Tell us more about yourself. How did you get in aviation and flight simulation?
Austin Meyer: Back in 1988 or so, after I had gotten my instrument rating in the calm and friendly skies of Columbia, SC, i found myself in San Diego, CA, working for duPont Aerospace, a small aerospace tech firm working on some excellent but unusual designs that I cannot discuss in detail. (Though I will say that one of the projects that they were working on is the well-known NASP, or National Aerospace Plane… a single-stage aircraft that can, in theory, take off from a runway and fly clear to orbit. Tony duPont, the president of duPont aerospace and my boss at the time, was the founder of the ingenious NASP concept. While the Space Shuttle and other conventional rockets use rocket engines to blast up to their 18,000 mph orbital speed, doing most of their acceleration in space where there is no air to slow them down, the NASP breathes air to run it’s engines, so it must do most of it’s acceleration in the atmosphere. This use of the oxygen in the atmosphere makes the vehicle much more efficient, but it also means that the aircraft must be flying at many many thousands of miles per hour in the air, which makes the plane hot! Circulating the cool fuel through the skin of the NASP to keep it from melting is one of the possible ways that this hypersonic flight might be achieved. I must admit I am not sure why the craft would not use well-insulated tiles like the Space Shuttle does… certainly those one-of-a-kind, hand-fitted, thick, always-coming-unglued tiles are expensive and a constant hassle for the Space Shuttle… of course, ciculating fuel to keep the skin cool has it’s drawbacks too! The SR-71 Blackbird uses it’s cool fuel to keep it’s skin from melting, and in fact is limited to much lower speeds than Mach 3 when it is almost out of fuel because there is no fuel left to absorb the heat! Open the SR-71 in X-Plane and rather than seeing a red LINE on the airspeed indicator to indicate maximum allowable speed, there is a whole red ARC! That big red region is the speed range that you can only operate in if you have enough fuel in the tanks to soak up the heat from atmospheric friction! Now you know.).
Anyway, enough about the NASP… that summer in 1988 or so in San Diego I took an instrument currency flight to keep my IFR skills up and had a hell of a time getting up to speed in the crowded, fast-paced, hectic ATC system of San Diego after the relative slow and laid-back ATC operations in my home state of South Carolina. After finally getting my IFR skills up to speed after about 3 or 4 flights, I decided that I wanted an instrument trainer to keep my IFR skills up on the personal computer. Microsoft Flight Sim was running on the little baby Macintoshes back then, but there were a few things I wanted done differently and I know MS would not change the sim just to suit me…. so I started a flight sim called, at the time, “Archer-II IFR”. I used it to keep up my instrument currency.
A Bachelors degree of Aerospace Engineering at Iowa State University soon followed and during my engineering studies there I expanded “Archer-II IFR” to be able to simulate most any airplane imaginable by simply plugging in the blueprints for that airplane, and letting the sim then figure out how the plane should fly based on those blueprints. I used the sim to test out various aircraft designs I had conceived (result: Cessna, Piper, Lancair and Mooney do just fine without me… my designs were too difficult to fly safely) and I renamed the sim to “X-Plane”, in honor of the series of aircraft tested at Edwards in the 60′s and continuing through today.
TH: You’ve been developing X-Plane for more than a decade now. How has Laminar research evolved in terms of market share since your FAA certification and the closure of ACES studios? Have any of the ACES developers shown interest in joining your team? Do you have data on what OS your customers use? Is there a majority of Mac users in the X-Plane community?
AM: No ACES people have contacted me. I don’t know my market share but I do know that X-Plane sales have been steadily increasing over the years, and we have around 100,000 desktop users, and 500,000 iPhone/iPod/Palm users, right now, with that number growing rapidly. Amongst desktop, maybe half and half Mac and Windows, with totally negligible Linux… like less than 2%.
TH: How has the company itself changed? Do you still write most of the code, and how many people do you work with?
AM: We have about 6 people now that contribute to airplanes, navdata, code and the like. I write maybe half the code now, more or less. But I do none of the art… We have people contributing art now (airplanes) that far exceed anything I could ever do!
TH: X-Plane gained a fair amount of exposure thanks to your iPhone apps. Tell us, what gave you the idea to port your simulator to a phone? Was coding for the iPhone very different than for computers? How much of X-Plane’s foundation did you use in the iPhone apps?
AM: My tech support and biz-admin guy, Randy Witt, convinced me to go to the iPhone, and we have sold about 500,000 units or so on the phone ever since. Coding is not that different from desktop, just a bit different. Ben Supnik coded the teeny bits that were different between desktop and iPhone. We grabbed bits of code from the desktop, and dragged them over to the phone.
TH: What do you think about the iPad? Are you planning on releasing iPad specific apps?
AM: Huh-huh! Ask me again on April 3, when it comes out. I may have some secrets about certain projects just completed behind the scenes, but lets just say to keep your eyes open on April 3.
TH: What process do you use in order to code for both Linux, Mac, iPhone and PC? What OS do you originally code on and why?
AM: I started on Mac cause it is a million times better than Windows. Then we just added bits of code to handle the same stuff (joystick, sound, etc) for Windows and Linux. Basically, about 15 year ago, I could choose Direct3D or OpenGL to do my graphics. Direct3D was what Microsoft was pushing, and would only work on Microsoft products. All the gaming companies were using Direct3D, because it was what Microsoft was declaring as the the standard for them… But only for Windows! OpenGL was the graphics engine that Apple was using. And linux. And SGI. And it could work on Windows, even though Mircosoft did not include the latest OpenGL drivers with Windows when they sold it! So, almost all the Windows developers bet on Direct3D. I bet on OpenGL, and used that. As a result, here we are, 15 years later, and the people that use Direct3D can support Windows only. But, with OpenGL, I support Windows, Mac, Linux, Palm OS, Google Android OS, and oh yes: iPhone and iPodOS which are also OpenGL. So having X-Plane in OpenGL let me move over to iPod and iPhone very quickly. The port was done in 2 weeks, to be very exact. And you saw that i have moved 500,000 units on the iPhone and iPod since. I get $7 from each of those sales, and have moved 500,000 units in the last year and a half, so get out your calculator, do some math, and see if i made the right choice to bet against Microsoft 15 years ago.
TH: One of the key arguments regarding the X-Plane vs. Flight Simulator battle is the superiority of your flight dynamics engine, which relies on the blade element theory. How does this lead to better flight dynamics? If the flight model relies on the visual model, wouldn’t you need it to be incredibly precise in order to fly realistically, and therefore require a lot of processing power?
AM: Yes, more processing power is required to run my flight model, for sure! No question of it. Here is how the model works:
1. Element Break-Down
Done only once during initialization, X-Plane breaks the wing(s), horizontal stabilizer, vertical stabilizer(s), and propeller(s) (if equipped) down into a finite number of elements. The number of elements is decided by the user in Plane-Maker. Ten elements per side per wing or stabilizer is the maximum, and studies have shown that this provides roll rates and accelerations that are very close to the values that would be found with a much larger number of elements.
2. Velocity Determination
This is done twice per cycle. The aircraft linear and angular velocities, along with the longitudinal, lateral, and vertical arms of each element are considered to find the velocity vector of each element. Downwash, propwash, and induced angle of attack from lift-augmentation devices are all considered when finding the velocity vector of each element.
Propwash is found by looking at the area of each propeller disk, and the thrust of each propeller. Using local air density, X-Plane determines the propwash required for momentum to be conserved.
Downwash is found by looking at the aspect ratio, taper ratio, and sweep of the wing, and the horizontal and vertical distance of the “washed surface” (normally the horizontal stabilizer) from the “washing surface” (normally the wing), and then going to an empirical look-up table to get the degrees of downwash generated per coefficient of lift.
3. Coefficient Determination
The airfoil data entered in Part-Maker is 2-dimensional, so X-Plane applies finite wing lift-slope reduction, finite-wing CLmax reduction, finite-wing induced drag, and finite-wing moment reduction appropriate to the aspect ratio, taper ratio, and sweep of the wing, horizontal stabilizer, vertical stabilizer, or propeller blade in question. Compressible flow effects are considered using Prandtl-Glauert, but transonic effects are not simulated other than an empirical mach-divergent drag increase. In supersonic flight, the airfoil is considered to be a diamond shape with the appropriate thickness ratio; pressures behind the shock waves are found on each of the plates in the diamond-shaped airfoil and summed to give the total pressures on the foil element.
4. Force Build-Up
Using the coefficients just determined in step 3, areas determined during step 1, and dynamic pressures (determined separately for each element based on aircraft speed, altitude, temperature, propwash and wing sweep), the forces are found and summed for the entire aircraft. Forces are then divided by the aircraft mass for linear accelerations, and moments of inertia for angular accelerations.
5. Get Back to Work
The process is repeated from step 2, and the whole thing is run over again at least 15 times per second. Aren’t computers great?
TH: Your fantastic flight dynamics engine has earned X-Plane FAA approval. Tell us more about how X-Plane can be used thanks to this license.
AM: The FAA is so much less discriminating than customers, that it is amazing. The requirements to get certified at the basic levels are very low! The framerate has to be like 10 fps or so, and the flight dynamics do not have to be accurate (!) for the lower levels of certification! X-Plane goes a thousand times farther than what the FAA requires, and the customers demand a thousand times more than the FAA standards for them to be happy. The FAA requires that if the joystick is unplugged, the simulator alert the user, and refuse to let you try to fly! That is actually the toughest hurdle we had to pass! I am not kidding! And obviously, that is an absurdly low hurdle to jump over.
TH: What most serious virtual pilots will look for in a simulator is realism, but how do you measure it? I imagine you haven’t been able to fly the Space Shuttle, but have you received feedback from real astronauts? The blade element theory implies that if a C-172 flies realistically in X-Plane, anything that has been accurately modeled will do too, but do you sometimes fly the real aircrafts, just to be sure?
AM: I have over 2,000 hours in a few dozen different planes, including a very small handful I have owned myself, and yes I have measured the real performance in real planes countless times, comparing it to the sim, to assure accuracy. The performance of the space shuttle is very well documented, and X-Plane holds to the documentation I have found well enough to get a pretty good feel for what the real shuttle is like to fly.
TH: Tell us about you real life flight experience. Your Columbia 400, if I’m not mistaken, was destroyed a few years ago, as a hangar collided. Have you replaced it? Have you ever been in tricky or dangerous situations?
AM: It was damaged a bit, not even close to destroyed. I got another one just exactly like it to replace it, simply because i did not want to wait for the thing to get fixed.. I had too much flying to do to go see customers in the custom-sim and FAA-cert areas, which are higher price-point. I have had a landing gear shake like a rough engine once, and a turbocharger pipe came off in flight, thus cutting engine power a bit.
TH: X-Plane 10, of course, is already on everyone’s mind. Amongst the most requested features are a better GUI, less numerous but far more accurate airplanes with more system depth, a real ATC system that’s at least as good as the one in FSX, and more accurate landclass. Which ones of these features are on your list? Do you have an ETA for X-Plane 10?
AM: All of them are on my list except the new GUI. I think the gui that we have now is perfect. I love it, and cannot imagine anything easier. Of course some will say I am wrong, so my statement to them is exceedingly simple: put up or shut up! Show me the beef! Show me a better UI than what I have now, and, if it is still as powerful, allowing the flexibility of what I have now, then I will sure give extremely serious consideration to using it!
But, if someone just wants to show me icons for a few pre-canned situations, like they have in Microsoft Flight Simulator, and say “see how easy it is? You should use that!”, then of course I should not use that GUI, because it does not allow the flexibility of X-Plane, which lets you set any parameter at any time in the flight.
Regarding X-Plane 10: unsure, but shooting for the top of next year!
TH: Add-ons for X-Plane are less numerous than for Flight Simulator, but they’re catching up in terms of quality. Any favorites that you use regularly?
AM: No, but that is only because I am so busy coding that I just don’t have the time to fly other people’s add-ons. But, of course, I think it is great that people are doing add-ons, and I want to encourage people to do more add-ons, and help with that in any way that I can!
TH: You’re well known for X-Plane, but let’s not forget that you also have other projects. In an interview with Tim Morgan, you mentioned the desire to build a Death Star. Any updates on this, as well as Space Combat?
AM: They are always on hold… forever on hold! I am always so busy with X-Plane i never seem to find time for anything else!
TH: In the 15 years that you have been developing X-Plane, what do you consider to be your most important breakthrough and feature addition?
AM: I don’t know! The most important things I did were not feature additions, but were done right the start. Those things are:
- Use OpenGL (which lets me run on so many different platforms that people can get x-plane for all sorts of devices).
- Use blade element theory (which gives such an excellent flight model for so many different airplanes).
- Start my own business with my own money, not any investor’s money (so me and my sub-contractors get all the profit. Not investors).
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