An Interview with Scot Bayless of Sierra on Aces: X Fighters

XF XF2
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Aces: X Fighters is one of the interesting prop sims on the horizon for this fall. Likely you've already read a preview in Computer Gaming World or somewhere on the net. This sim is looking hot! I know, you hear that often, but perhaps that is because the level of complexity and detail in so many sims this year has achieved new heights.

Remember too that Dynamix has been "part of the Sierra Family" since just after Red Baron. Dynamix was responsible for Aces of the Pacific, the 1946 add-on, and Aces Over Europe, so they are far from newcomers to this field. The programmer who is doing the flight model for Aces:XF work, was the flight model programmer for AOE and worked on the original conversion of the Red Baron Flight model to AOTP. Recently we had a chance to talk to the producer about this sim. Here is the result:

CSim: Scot, the life of a sim producer is a busy and stressful one. I bet you don't fly on the PC much for fun....What do you do when you need a break?

Scot: A fine question. I guess it depends mostly on what time of day we're talking about. I'm an early riser, so the 4:30 to 6:30AM slot is usually my game time. I've been playing a bit of everything lately - from Warbirds (t_rex) and a little of Jane's Long bow to Diablo, MOO2, History of the World, Dungeon Master and a sprinkling of old Sid Meier favorites.

Other times, it's usually golf or playing with my 9 month old son who's by far the most entertaining hobby I've found.

Csim: What is your role in the production of Aces: X Fighters?

Scot: In a nutshell, I'm the guy who has to make the tough calls. We've got an outstanding team on this gig. They don't need to have their hands held on the day-to-day stuff. Now that we're in full production, mostly what I do is play "keeper of the vision" to help the team stay focused on what makes X-Fighters special - and fun.

Csim: Give us some background, how did this project get started?

Scot: I left Sega in late 1994 to partner with a couple of industry veterans who'd opened a small development house in Oregon. After two years there, it was clear that things weren't working out the way we'd all hoped and I was looking around for other opportunities.

I was considering a couple of executive positions in the Bay Area when, pretty much out of the blue, my brother Graeme called me to let me know that Dynamix was looking for directors. After five minutes with Jeff Tunnell and Randy Dersham I knew I'd found a home. The chemistry was astounding. We were literally brainstorming projects in the interview.

X-Fighters was one of three or four ideas I threw at them in the course of that discussion. I said something like, "You've got this awesome sim engine. You've got one of the most flexible flight models around. Why not give people a chance to fly all those really cool planes from WWII that nobody ever puts in a sim?" I remember Randy's eyes kind of lighting up as I said it.

That was almost exactly a year ago and three weeks later I was sitting in my office at Dynamix, working on the preliminary design doc for X-Fighters.

Csim: Do you have a favorite WWII sim on the PC, and why?

Scot: Two part answer:

"Their Finest Hour" for pretty much the same reasons that CGW put it in their Hall of Fame. It broke new ground technologically, creating a more immersive air combat sim than anyone had ever done before, but more importantly, it was just plain fun to fly.

"Warbirds" because it effectively re-invented the WWII air combat sim as a huge multiplayer experience. There's a culture growing up around the game that I think a lot of people may have vaguely anticipated, but the ICI guys actually revealed. My hat's off to them.


A nice cockpit shot...

Csim: Can you tell us something about the design goals of Aces:XF?

Scot: X-Fighters has three goals:

1) Give players a fresh perspective on one of the most amazing periods in aviation history. Think about it. Between 1936 and 1945 aviation went from 150hp piston engines, doped canvas and .30 cal machine guns to 2000lb thrust axial flow jets, stressed aluminum laminar flow wings and guided missiles. I still get kind of starry-eyed when I think about it.

2) Give players a chance to find out for themselves whether all those legendary exotic planes that nearly made it into the war were really what they were cracked up to be. Imagine what it'll be like to put a P-80 up against the Go 229.

3) (and this is really the big one) Give players the chance to make their own design decisions and then try their handiwork out against other pilots. You're a boom 'n zoom fan? No problem. Slam a couple of high powered turboprops in your P-38 airframe, load that baby up with 20mm cannons and go hunting bear. Just watch your airspeed...

Csim: What areas in Aces are ground breaking?

Scot: The obvious answer is the aircraft design component of the game. It's something nobody's really tried in a WWII air combat sim. It's one thing to offer vehicle design in a fictional context where internal consistency and game balance are the only issues you have to deal with. Doing the same thing in a well documented historical situation is far more challenging. We've put tremendous effort into researching the technologies of the period and their effects on the flight and combat characteristics of the planes that used them.

The somewhat subtler answer has to do with the technology behind the game. Aces: the X-Fighters uses Dynamix's newest sim engine, the one being used to develop "Earthsiege 3" and "Fear". It's 3D card support, multiplayer capabilites and tremendously flexible open architecture put it far ahead of anything else I've seen.

XF Cockpit

Csim: What aircraft will we be flying?

Scot: As you might imagine, the list is still a bit fluid, so forgive me if I don't give you a definitive answer. I can say, though, that, in addition to the usual complement of well known fighters, the list of player flyable airframes will definitely include the following:

Csim: X Fighters seems to be an interesting mix of history and "what if?" Tell us about the "what if" factor and how its modelled in the sim.

Scot: This has been simultaneously the most exciting and most difficult part of the project. Starting with the Sierra ProPilot flight model, which was exceptionally robust to begin with, we've gone far beyond what it was originally designed to do. We've had to literally rewrite parts of the model in order to extend its already considerable dynamic range.

We're also making a deliberate choice in the aircraft designer portion of the game to couch the player's understanding of the predicted performance of a design in the knowledge of the period. All of the predictive computations are based on Von Mises' landmark text from 1936. This book was actually a classified document under the 3rd Reich and represented the state of the art in aeronautical engineering at the time.

That's the good news. The bad news is that Von Mises wasn't always right. There were aspects of fluid dynamics that were poorly understood in the 30's and 40's and made for some unexpected behaviors when planes went from the drawing board to the wind tunnel. In game terms, the net effect of this is that the player will need to develop, through experience, an intuitive sense of how to "read" the performance predictions.

The other aspect of "what if" has to do with the course of the war. One of the things I've always found frustrating about slavishly accurate historical simulations is the sense that, no matter what I do, things will come out the same in the end. While this may be true in the real world, it doesn't necessarily make for a good game.

What we do in X-Fighters is steer the war on the basis of your squadron's performance. If you make a strong showing for the RAF in 1940, you'll see victory in the Battle of Britain and find yourself contributing to the Allied bombing campaign over Europe. Blow it, and you'll be intercepting ground attack missions and strafing landing craft in Operation Sea Lion. X-Fighters isn't so much about recreation of historical events as it is a recreation of historical conditions. What happens after that is up to you...

Csim: Will X Fighters use the RBII engine or has a new engine been developed? What about 3d hardware?

Scot: X-Fighters is based on our newest sim engine (see above) and, yes, we do offer native support for the most popular 3D chipsets. Performance is awesome. As long as we're not blowing the texture cache, we can push tremendous frame rates on fast chipsets like the 3DFX.

Csim: What level of detail will we see in the terrain and ground objects?

Scot: This is always a tough one to answer because there are so many axes to the question. The short answer, though, is that we're modeling a huge chunk of the Western Front (from just east of Penzance to just east of Berlin and just north of Dijon to just south of Odense) on 128 meter intervals. We're using mip-mapped, lit, shaded, textured terrain with a highest level of detail that give us a resolution of 1/2 meter per pixel. Ground objects are textured at considerably higher detail.

The effect of this is extraordinary. When you're flying down in the mud, you can actually "see" how high you are above the ground. I think this is the first time I've ever been able to fly within 50 feet of the dirt without having to watch my altimeter constantly.

Csim: What level of detailing will we see in avionics? For example, will prop pitch be adjustable in the appropriate aircraft?

Scot: From the outset, one of our secondary design goals has been to give players the most realistic cockpits anyone has ever seen in a WWII flight sim. The cockpits are 3D objects that include the wings and other visible surfaces of the aircraft. The instruments have been carefully researched and, to the extent possible, accurately reflect the performance and capabilities of the real thing.

This kind of cuts both ways, though. For example, many of the earlier fighters didn't have an artificial horizon. They used separate pitch, heading and roll indicators. In X-Fighters, that's what you'll see.

As to controlling the pitch of your prop, it turns out that virtually all of the propeller-driven aircraft in use by 1940 used constant speed props. Pilots typically had very little direct control of pitch and, partly as a concession to game play, we decided to model all props as constant speed.

Csim: How advanced is the flight modelling?

Scot: We've got some pretty savvy aviation guys here. Our principal flight model engineer did the flight models for both "Aces Over the Pacific" and "Aces Over Europe". The ProPilot flight model is a major update of the flight model developed by Sublogic for their line of civilian flight sims, a model that's been respected for years for its fidelity. In short, our model's as accurate as we know how to make it.

I think, however, that a lot of inexperienced players will be surprised at how twitchy some of these planes are. For years, flight sims have trained people to think of high performance WWII fighters as kind of "air cars" that you just point at a target.

In truth, they were far more demanding than that. Every airframe had its own quirks and instabilities and X-Fighters will reflect that (assuming you have all the realism settings turned on).

Csim: Will the AI pilots use the same flight model as the virtual pilot?

Scot: Yes they will and there are some other things we're doing with the AI that I think will surprise a lot of people. Because of the huge variety of airframes and configurations in the game, we couldn't use the traditional approach of writing specific AI for each plane. Instead, we're using techniques that are still hot news in the academic community. Hint: check out Carnegie-Mellon's website.

Csim: Physics modelling is another area where technology is improving, and Activision/Parsoft have done some great work there. What will Aces give us in this area?

Scot: Aside from real projectile physics, ground physics, low altitude turbulence, foggy clouds, real flight model effects of damage, real weapon penetration and damage effects, debris from damaged aircraft, highly realistic visual and fatigue effects of extended periods at high g's? Hmmm... not much. ;)

Csim: Other than suspension of disbelief the area that keeps virtual pilots coming back for more is identifying with the pilots they fly. How will X Fighters involve the player personally?

Scot: In X-Fighters campaign, you're a squadron commander. You fly with your boys, mission after mission, watching them learn to survive or watching them make the mistake that kills them. They have faces and names. They have unique skills and styles of combat. They learn from their errors and improve over time. You're responsible for assigning them their positions in the squadron, for decorating them, for promoting them, for replacing them when they're killed.

Obviously, this is a bit of a departure from the typical "player as one of the rank and file" approach. We felt very strongly that the interplay of resources and technology with the skill and daring of individual pilots was brought much more sharply into focus by casting the player in the role of commander. It's a hard job, but a compelling one.

Csim: An aircraft designer module is bound to add loads of interest and entertainment value. Tell us more about this feature in X Fighters?

Scot: In short, the designer lets you make the high level decisions that real aircraft designers were faced with. What kind of airframe do we use? What skin do we put on it? How rugged should it be? How many hardpoints should it have? What kind of propulsion should we use? How much fuel? What kind of weapons? Where should we mount them? How much ammo? Self-sealing fuel tanks? Non-strategic materials?

The list is a long one and the number of possible choices is astronomical. We don't burden the player with arcane engineering issues like propeller geometery, but we give him more than enough flexibility to pursue his personal philosophy of air combat. Whether you're into heavily armored gun platforms or supremely agile eggshells, you can put your personal theories to the test.

Csim: The designer feature is integrated with the pilots performance in the sim. How is this implemented?

Scot: The currency you use in the campaign is "influence". Put simply, it's a measure of how Fighter Command rates your squadron's performance and virtually everything you do in command of your squadron costs you some of that influence. Requisitioning a new pilot, replacing a pilot you don't like, decorating a pilot (which then earns you a little extra influence each week), repairing planes, replacing planes, recommending changes in air doctrine all come with some influence cost. In short, you earn influence by flying successful missions and spend it keeping yourself and your pilots in the air.

In the campaign, the designer is available at any time. You can design whatever you like, whenever you like, but to be able to *implement* a design, you need to accumulate enough influence with Fighter Command to get them to build what you've cooked up. The influence cost of pitching a design to the big boys depends on the newness of the technologies and components it uses as well as the simple quantities of those components.

The net effect of all this is that simple mods like switching a couple of MG's for cannons or moving up to a slightly more powerful engine can be really easy to get approved, but talking Fighter Command into building a new fighter based on a recently developed airframe loaded with the very latest jet engines and brace of brand new 55mm guns is likely to take every last bit of pull you've got!

Csim: Will virtual pilots be able to share the aircraft they create with others?

Scot: Yep. We're externalizing aircraft designs so you can move them around as you see fit. Of course, *I'm* not giving away my pet designs...

Csim: Integration of the ground war with the air war adds a lot of depth to the newer simulations. What approach have you taken in this area?

Scot: In X-Fighters, the ground war is definitely there, but it's always treated as a context for the Air War, rather than something you interact with in any intimate way. The types of mission you fly and the construction of those missions is dependent both on the state of the ground war and on the air doctrine in effect on both sides of the conflict at the time. For example, if your side's air doctrine is focused on tactical bombing and the other side is big on air superiority and you're currently supporting the defense of Germany, you're going to draw a lot of close support missions in the Rhineland opposed by sweeps and intercepts.

Csim: Can you tell us about the command structure for a squadron leader? Will we be able to use the radio when that technology is developed during the course of the war? How much control will the squadron leader have over his flight?

Scot: One of the things that sets X-Fighters apart is the degree to which you interact with your squadron mates. You issue commands to pilots with simple key-based commands, but what you'll hear is your voice issuing a verbal order to the pilot(s) in question.

The granularity of your command over the squadron is at the section level. This is a bit of a fiction since the Germans used a 3 plane kette, but we decided that for game play purposes it made sense to standardize.

Csim: How will a pilot become a squadron leader? Once achieved, will we also have the ability to structure or plan our flights?

Scot: In the original spec for X-Fighters, we'd planned to let you grow into the role of squadron commander, but we eventually realized that by doing so we deprived you of one of the most interesting parts of the game until you were halfway through the war. So now you start the game in command of the squadron and have responsibility for everthing from training pilots to supplying aircraft to recommending theater wide changes in air doctrine.

Csim: Will we see a wind model in the sim?

Scot: Yep. Wind and turbulence are both modeled. We still haven't decided whether we'll include vortex effects from heavies, though I suspect they'll be there.

Csim: How will new technologies impact X Fighters? Will we see surround sound, force feedback, support for vr headsets?

Scot: Some of this is still up in the air. The big issue here is schedule hit vs impact on the player community. If I had infinite resources at my disposal, we'd support every I/O device known to man, but I don't. We'll probably support the major force feedback sticks. Headsets and surround sound? We'll see.

Csim: What can we expect for later add on scenarios?

Scot: This really depends on a lot of things I can't predict right now, but I hope to see at least an eastern front add on. One of the things we discovered in the course of our research for X-Fighters is the fact that the Russians were very much at the forefront of aviation in the late 30's. If a few decisions had gone differently we might well have seen Soviet domination of the air very early on. I'd love to explore that.

Csim: Janes and iMagic have begun shipping their sims with spiral bound manuals, a BIG improvement in my mind. Will we see this trend with Sierra also?

Scot: Don't know yet. It's something I really want to do, but there's some really cool stuff I want to include in the manual that I'd even sacrifice a spiral binding to keep. Guess we'll see...

Csim: What do you feel is the coolest feature of X Fighters?

Scot: For me, it's unquestionably the notion of, "I build a plane. You build a plane. We get up to 10,000 ft and find out who the big dog is." Looks like a lot of people here at Dynamix agree, they keep stopping me in the hallway and asking me when they can start blasting each other on the local net.

Csim: If you had all the time and talent in the world, what would you do when Aces: XF is complete?

Scot: Already working on it. I hate being mysterious, but all I can really say at this point is that it's very cool, uses our 3D technology in some pretty ambitious ways, explores an area of serious simulation that's been largely ignored and offers lots of opportunities for deep play and personal engagement. This one's gonna take a while though, so don't expect to see it right on the heels of X-Fighters.

Csim: Sounds cool.. geez, I hate mysteries! So how soon can we expect to see Aces:XF?

Scot: For mostly strategic reasons, we recently moved the ship date out to the first quarter of next year.

Csim: Aaarrgh! Ah well.. thanks Scot, and best of luck!!

Scot: You're more than welcome. And feel free to pass on this e-mail address to your readers. The team would love to hear what they have to say.

[email protected]

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Last Updated August 30th, 1997

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