Birds of Prey Interview? - By Derek "Crossfire" Bond - Page 1 of 3
In recent years the flight sim community has been fed a steady diet of WWII, helo and jet sims. Fans of World War I aviation have been neglected. Not since the days of Red Baron and Fighter Corps Gold have we seen a full-fledged WWI flight sim. Developer Wings with Wires (WwW) is looking to change that with their upcoming flight sim "Birds of Prey" (BoP). If it all comes together, this looks to be a very promising sim, and definitely one to keep our eyes on.
FW: Tell us about your team. Who are the members, and what are they
responsible for in the development of Birds of Prey? I understand you guys
aren't developers in the traditional sense of the word, but simmers who felt
they can do better. Is this the case?
WWWBryan Russell from Australia is our programmer, Paulo "Nuum" Mendonca from
Brazil is our artist and primary modeler, Dave Housteau (USA) is our game
design coordinator, and Kurt "Pang" Wheaton (USA) is our flight modeler. I (Sean Baker) answer questions and drive the get-away car ;)
You could say we are not developers because this is not our full time job.
Other than that, we’re pretty much like most developers I suppose. We
certainly don’t feel that "we can do better"- quite the opposite really, we
are very humbled by the amazing work that has gone into all flight
simulators. I think it is our admiration for the other sim developers that
has inspired us to move beyond creating user mods and pushed us to create a
new title. But the main reason for us perusing this venture is our shared
belief that the OpenPlane engine is an amazing base for a new WWI flight
sim.
FW: When will the sim be released?
WWWWe are currently planning on 4th quarter 2003. Actually development is on track given the efforts we have been able to put forward. Most in the team
have had significantly less time to devote to the project than expected this
past year, mostly due to the economy and our need to focus more on our other
obligations. But, we are all feeling good about being able to return to our
prior schedule and work will again pick up pace.
FW: How will sales/distribution be handled? Will Birds of Prey be a download,
or CD? Do you plan to sell through brick-and-mortar stores? One-time charge
or monthly fee?
WWWThis will depend on many things, and we won’t know the answer until we have a good BOP alpha running. We are leaving the door open to release the game
in a way that is best for the spirit of the game. We have been building up a
strong ability to self publish if we need to.
FW: Can you predict the system requirements at this point?
WWWLike many modern flight sim games, BOP will work across a variety of system capabilities. Users will be able to set the level of detail in the world in
order to balance graphic fidelity and frame rate to suit their taste. To
best enjoy the special features of BOP, I would say you should start with a G-Force 2 card or better- currently we are developing using the G-Force 2 as a baseline. The game should run smooth with the older cards, but you will not see the full fidelity of the models. Really, BOP will be a very fun and visually appealing game even with those older technology cards running the game!
FW: Birds of Prey uses the Open Plane engine, the same used for Fighter
Squadron: Screaming Demons Over Europe. What changes if any can we expect
in terms of physics or graphics from FS:SDOE?
WWWBOP uses a completely new renderer and an updated OpenPlane file format that brings the OpenPlane engine up to state of the art. We have spent allot of
time experimenting with and perfecting the way light plays in the BOP world.
The actual models must be created in harmony with the renderer to achieve
the results we desire. The renderer can really bring different materials to life, and the models contain a large amount of information about the materials and how light should interact with them. We have also come up with some special shading techniques for creating a more realistic looking result. The polygons in the BOP models are carefully
created in just the right way to give the desired result when viewed "under the lights" of the renderer. The difference in appearance between a sharp edge and a blunt edge can make all the difference.
The physics engine will not be changed, but it will be enhanced. We will be
focusing on some of the weaker aspects of OpenPlane such as engine
performance and aircraft stability / spin entry.
FW: Can you please describe the benefits of the Open-Plane architecture?
Where does it excel? Have you encountered any limitations?
WWWThe real value of OpenPlane - and where all the hard work went- was into the open system. As most programmers know, creating a powerful open system takes
much more work and careful planning than it does to create a very specific
application. The benefit of this open system is not only for users who want
to create add-ons, but it also very much streamlines our own development. Artists and modelers can put there work directly into the game in final format with flight and damage modeling without ever needing to consult the programmer! Likewise, the programmer
can pass new features and options over to the design guys, it is a great system.
OpenPlane’s flight modeling can be best described as erroring on the side of
detail and completeness. Since OpenPlane has no idea what kind of aircraft
it will be modeling, it can make few assumptions about the flight behavior.
This makes for a very interesting and subtle flight model - you can have
much more fun experimenting with flight in the OpenPlane world. OpenPlane aircraft have those quirks like you find in real aircraft- personalities that are hard to find in other sims. The downside is that this takes more processing power (we can have less simultaneous aircraft) and the flight models rarely match published flight statistics
exactly. In essence, you can capture more of the personally of a Nieuport with OpenPlane than with other game engines, but your top speed and climb rates might be off a bit. We don’t just enter flight specs in- we work building a replica Nieuport in the simulation and
then try to make sure the weights and airfoils, etc. all work to produce the expected performance. This can be a big plus when you are trying to model aircraft with no known flight stats - we can come pretty close just knowing the weights, engine power, prop and wing airfoils, and other measurements. You could say that we are restoring flight
performance specs!
As far as limitations, there are some- some we must stay within and some we
can move beyond. OpenPlane will never support huge fur-balls with many
dozens of aircraft in close proximity, but it can certainly support the
quantity BOP needs to have in order to realize it's game concept. There is no limit to how many aircraft can be in the BOP world at any one time. The only limiting factor is how many aircraft can be in very close proximity.
Right now aircraft tend to be over-stable in certain areas of their flight
envelope, we are looking into what might be causing this. Aircraft tend to
recover from spin situations too easily- we have been able to determine that
all the right things are happening to get the aircraft where it should go- it is only just after this point that the aircraft seem to "fly" a bit too well. I’m sure we will find the issue and
update the OpenPlane engine with the solution.
FW: How do you go about testing for flight model fidelity? Are the planes
built, then tested to see where they fall in respect to the real aircraft?
In case there may be some discrepancy between the results in the simulation
and what you had expected given real-world data, how do you handle that?
Have you been taken by surprise once you've flown a newly-built model?
WWW Fortunately the hard part has already been done for us! The OpenPlane engine is the basis of our flight model physics and aerodynamics. Originating from PC flight sim pioneer Eric Parker (Hellcats over the Pacific, A10 Attack!),
and brought forward to "Fighter Squadron: Screamin' Demons over Europe" by
Michael Harrison and his team-OpenPlane is a well-proven engine. Inertia Games tuned the OpenPlane engine for Radio Controlled flight in the Ripmax R/C Simulator title. Wings With Wires is adding more properties to OpenPlane that will highlight the attributes peculiar to World War One flight, such as the gyroscopic effects of rotary
engines. But that doesn't mean that the modeling is easy.
OpenPlane models the physics of flight by generating the forces that act on
each component of an aircraft. So, we need to feed it things like the actual
area of the horizontal stabilizers, their weight, the amount of deflection
of the elevator, the coefficients of lift, drag, and moment of that whole
assembly, the center of gravity of that assembly, it's aspect ratio, the angle of incidence relative to the fuselage, the Oswald's efficiency factor, well, I'm getting carried away.
Suffice it to say that this is a partial list of properties just for the
horizontal stabilizers! Then we do the same thing with every other component
of the aircraft, and set the proportions correctly between components as
well. After all is done, we do an actual weight and balance as any engineer
would, to determine the proper center of gravity of that particular
aircraft. Too far forward, and the plane may not turn fight very well - too far aft and the plane will be unstable in pitch, more likely to spin! Incidentally, not all planes were set up alike, and we have the ability to let pilots and riggers determine some aspects of
the flight model for themselves. FM's will also be affected by the rigors of combat, and suffer from fatigue and battle wounds. Careful with that old crate!
We also have modeled the airfoils carefully from known dimensions. We take
the unique coefficients of the airfoils and apply them to the various lifting surfaces of the plane - wings and stabilizers, as well as the fuselage and even the undercarriage! This is one really exciting aspect of OpenPlane, the fact that the airfoil section is influencing your airspeed in a hard turn or a steep dive, or in straight level flight. This largely affects the differing flight characteristics from plane to plane. The airfoil for a Spad XIII is
radically different that the Fokker Dr. 1, for example, and the flight models of these planes will demand that they be flown in striking similarity to their real life counterparts!
Once the aircraft is put together with everything as close to historical
specifications as we can possibly determine, we go fly it! We begin to
critically evaluate whether the plane's flight model matches what we know
about it historically. Was this plane known as being unstable in pitch? If
we've put in all the right stuff, chances are that it will be in OpenPlane.
If it's not, we can begin to do the tweaking that mirrors real life aircraft
design. Are we properly balanced and rigged? This is where the trial and error, or the art
- if you will, comes into play. This usually involves minor adjustments to
angle of incidence, control throw, and weight distribution. We also have a
unique partnership with Memorial Flight in France, who will be helping to guide our FM design process. Who better to turn to when modeling the Fokker than someone who is flying one?
One thing that is missing from our calculations is tables - tables of rate
of climb, rate of turn, top speed, stall speed, etc. OpenPlane models the
components themselves, so rate of climb is determined by the actual forces
that act on the airplane; things like horsepower, total weight, propeller
pitch, lift, and drag to put it simply. Turn rate will depend on forces like
lift, drag, moment, center of gravity, control surface deflection, and not
on a table that determines how fast that rate should be. Of course this
means that an awful lot of flying will be going on in the process of design, which is probably what makes the whole job so enjoyable.
Finally, the aircraft need to be evaluated against each other, again - to
see if they match what we know - or think we know about them from history.
We may be in for some surprises as well!
