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Flight Model in Simulation Design: A Forum

  by David Zurawski

 

Playnet Q3&4

Q3) This is a good question. We are using lots of NACA reports, Wartime flight test evaluations, pilots manuals, and snippets of stuff we dig up out of the strangest places. We use ex-military sources, web collections, and libraries of the truly insane (Imagine having detailed info on the MS 405!). If you dig deep enough, you can find anything! The first part of modeling our planes is all math...areas, weights, roll inertias etc. We get that stuff from detailed construction stats and then turn it into data that our engine reads.

Then it's wind tunnel time, check to see if the math worked or if there were any errors. Then we detail the performance parameters, this is where you find out how close you are by cross referencing the way it flies in the sim with what the real aircraft's flight tests say, and what the pilots reported. Stall, spin, pre and post departure character, and any other stuff that's specific to THAT plane needs to be looked at. Sometimes it's not easy to get a plane to "sag" or "wobble", or "burble", those are very subjective terms. But that's where the factual nature of our engine is so rewarding.

Usually, if you plug in all the numbers right, and you took a LOT OF CARE in measuring and calculating the specs, the plane will act like the reports. The first few times we were kind of dumbfounded actually, and wrote it off to "luck", but it's turning out to be fairly consistent, so we're not going to complain. But again, every once in a while you run across a plane that has very little data on it, or widely flawed or even conflicting info.... Sigh, that's when you have to get the scalpel out!

Q4) Well, I'm not the most experienced producer around, but I'd have to guess that consistency is a big challenge. Getting planes to act their age together. You may model a P36 and believe it's spot on, but then you get it in the air with a A6M2 that you also think is accurate, and you say "hmmm, is this what it was REALLY like?" There's simply no-way to get all the nuances of what prop combat is like, you have to make choices and hope that they have no impact, or at best a mild impact on a model that's 20 planes down the list.

Our philosophy is simply this: Give the players the benefit of the doubt in regards to their ability. Sure there are guys out there who can't open a can of beans and talk at the same time, but they won't get flight sims no matter HOW easy you make them. The guys who love flight sims, end up staking a lot on the "feeling" that they are good combat pilots. Well, delusions aside, they ARE good combat pilots...INSIDE THE BOX. As a producer you have to give them challenging models that feel right. So they can work hard to gain experience and get better.

The level of ability of WW2 sim pilots has risen incredibly in the last 5 years. And it's a direct result of more challenging models being produced. The work that Dale Addink and Doug Balmos did on WarBirds had a huge impact on the WW2 prop sim market, and the learning curve of the WW2 flight sim IMO. Marketers and suits will say that it needs to be easy-to-fly in order to make money, and I feel that that is a mistake.

The WW2 flight sim community as a whole is smarter than they were a few years ago. These guys are looking at the NACA reports too, and don't think for a minute that they are not. Especially when it comes to "their baby", whatever plane their grandpa flew in 1944 etc. So to make a short answer long, the real challenges are consistency, and giving your audience a challenge.

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AOA

Wayward Design Q3&4

Q3) Throughout development, we have uncovered extensive research materials into the specifications and flight characteristics of all the aircraft we have modeled. This includes, in our case, detailed test-pilot reports of both allied and captured axis aircraft. During Beta test, pilots who have recently flown the actual aircraft will put the aircraft through their paces. Where this is not possible, for instance with the Me163, we will use the combined wisdom of pilots from other aircraft of similar design and performance.

Q4) Ground physics. An "impact" is by its very nature something that involves very large forces for very small amounts of time. In flight, most physics engines recalculate the physics about every 33ms. This is nowhere near being a high enough frequency for realistic ground behavior. I mean taxiing over bumpy grass, belly landing, crashing, dipping your wingtip onto the grass. We deal with this by using asynchronous and variable frequency impact physics.

Parsoft / Inertia Q3&4

Q3) There are a number of sources that we use when researching aircraft. These include independent researchers who do the work professionally, and book and web resources.

Q4) All in all, it's the conflicting information that's available. There were a great number of variations made for many of the aircraft from that time period. These include line and field modifications, which are not always noted in official and unofficial documents. When researching a particular aircraft we have to carefully compare the documentation with personal accounts from the war in order to provide the best simulation possible.

Response

I'm hesitant to say this, but based on the above statements simulation developers are faced with a dilemma. Obviously older technologies like simple "data-lookup" tables are far easier to use to convey specific flight-performance specifications.

But simulation consumers are demanding higher fidelity flight models, which by their very nature require vast amounts of "specific" data and specifications, many of which are extremely scarce if available at all. That coupled with the light-speed advance in technology makes the developers task a daunting one.

With today's high-fidelity flight models, it's no longer sufficient to simply model the aircraft's flight performance, now developers have to model the "aircraft." This includes having hard data for:

  • Surface area = Not only for the wings, but also for the horizontal stabs, rudder, ailerons, elevators and the fuselage.
  • Airfoil data = Including chord thickness, moment of inertia and airfoil data for any leading and trailing edge devices.
  • Specific object weights = How much DOES the left aileron of a P51D weigh?
  • Center of Gravity = Not only for the aircraft as a whole, but also for specific object components.
  • Degrees of throw for all control surfaces.

As you can see … simply knowing the maximums for alt, airspeed and roll just don't cut it anymore.

Go to Part IV: New Techniques

 

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