FlightGear
By Chris Hodge (26 May 2007)
INTRO
he open source
software movement has created a number of impressive products that
reach a level of quality rivaling professional software. These
products often begin as one person's graduate school project, but
continue to develop with volunteer input from many people over the
course of years. The best of them reflect a lot of hard work and
pride on the part of the contributors, and the fruits of these
efforts are a boon to the rest of us. Even if we don't have a serious
need these products, they give us a chance to dabble in things
without having to spend a lot of money on a professional grade
software package. Some of my favorites in this category are the
Firefox browser, the GIMP (Photoshop alternative), Inkscape (a
vector-graphics drawing application), and Audacity (digital recording
and editing).
FlightGear is a feature-rich, multi-platform, open source flight
simulator that has been under development for over 10 years. A full
history and philosophy of the project is available at their web site,
www.flightgear.org,
so I won't try to tell the whole story. I'll simply give a quote from
that site sums up the spirit of the project:
"FlightGear is a free flight simulator project. It is being developed through the gracious contributions of source code and spare time by many talented people from around the globe. Among the many goals of this project are the quest to minimize short cuts and "do things right", the quest to learn and advance knowledge, and the quest to have better toys to play with."
I have only recently decided to give FlightGear a try, and I can tell
you it is a very impressive effort, and it deserves more attention
from the flightsimming community. You don't have to be an
anti-corporate radical, or someone who can't abbreviate Microsoft
without using a dollar sign, to be an open source enthusiast; many
flightsimmers who are quite happy with the offerings from Microsoft
will find that FlightGear is an worthwhile complement to the
commercial product, and that the two can coexist peacefully together
on one hard drive.
If I have not yet piqued your curiosity enough to make you rush off to the FlightGear download page, consider another motivation: performance. It is a stated intention of the developers that eye candy should not compromise performance. Your mileage may vary, but on my system (2.2 GHz Athalon processor, 1 GB RAM, 512 MB ATI graphics card) FlightGear flies dramatically more smoothly than FS2004 (not to mention FSX). There is absolutely no hesitation when I pan the view around. I have noticed microstutters on a few occasions, but overall I don't give a second thought to frame rates. Still another reason to consider FlightGear: if you have another computer in the house besides your flightsim computer, maybe an older system, why not see how FlightGear will run on it? It won't cost you anything beyond the inconvenience of a large download.
While reading the following comments, it is important to keep in mind
that work on FlightGear is ongoing. Many limitations mentioned below
will probably be addressed at some point, if they have not already
been addressed. This review is based on version 0.9.10, the most
recent version available with a Windows installer. However, this
version was made using source code that is about a year old. There
has been much development since then, but since these guys have day
jobs and families, they have not had the manpower to put together a
more recent install package. For those who want to put in some extra
effort, it is possible to get more recent versions (see the web site
for details), but the procedure may be a bit too complex for the
casual simmer.
THE BASE PACKAGE
Downloading the product is easy, although at 135 MB this could be a challenge for those with slow Internet service. Once downloaded, the installation is straightforward. Installations for other platforms are available, though I have not tried them.
With the base package you get the simulator, a wizard called FGRun
for configuring flights, an assortment of planes, and scenery for the
San Francisco area. Also included is extensive documentation in pdf
form. The default planes are a nice mixture of GA, airliner, and
military jets, some warbirds, one helicopter, an R/C plane, and a UFO
(!). Additional planes, and scenery for the entire world is also
available for download separately.
The sim itself has a menu driven interface, and can be launched directly from a command prompt. But most users will use FGRun program to set up flight parameters. FGRun is a GUI where you specify airplane, location, weather and time, as well as some other options. When you click the Run button it will fire off the simulator. This two-part interface takes some getting used to, because while some options, such as weather and location, can be changed within the simulator, others, such as airplane you are flying, cannot be changed without exiting the sim.
Startup time for FGRun is negligible. As for FlightGear itself, let
me say that if you've gotten into the habit of taking the dog for a
walk while FSX loads a flight, you're in for a pleasant surprise: the
actual simulator will be up and running much faster than you are used
to.
FlightGear includes some sophisticated features such as the ability to fetch real world weather, multiplayer support, and a landable aircraft carrier off the coast of San Francisco. There is a HUD (heads up display) that displays in the appropriate place in military jet cockpits, but you can also invoke a full screen version of it while flying any airplane. Finally, there's a little bit of AI traffic included, as well as a rudimentary text-based ATC.
Many major brand joysticks are supported. If yours is not, it might take some minor hacking to make it work, but there is an included utility to assist you. The GUI offers no ability to customize button assignments, but if you want you can edit the .xml file that defines the behavior of your stick. I use a Saitek Evo without any customization, and it works well.
A nice feature is how the mouse works. The right mouse button toggles
the mouse through three modes: standard, mouse yoke, and view
panning. This flexibility enables one handed flying, for when you
want to sneak a flight while talking on the phone, or (as in my case)
holding a baby.
THE VISUAL EXPERIENCE
You can tell from these screen shots that no, FlightGear will not replace MSFS for most people who appreciate ultimate visual realism. The graphics both inside and outside the plane generally do not measure up to FS2004 (certainly not FSX), but given the performance gain, it's not a bad trade off. On the other hand, there are a few features, such as aircraft self-shadowing, and curvature of the earth at high altitudes, that Microsoft achieved only with their latest release. Also, they have one feature that has yet eluded Microsoft: sloped runways.
Clouds are rendered fairly well. The overcast effect is convincing
from below or above, though you will find it is paper-thin when you
pass through it. Other clouds are rendered in 3D. The ground textures
can look surprisingly good at times from altitude, but the
transitions from one landclass to the next are rather abrupt. Autogen
is sparse and fairly crude, but it helps give a sense of altitude.
Airport lighting and runway textures, however, are pretty good.
The scenery files include SRTM terrain data as well as vmap0 data for lakes, rivers, roads, etc. The airports that I have visited are reasonably well represented. There are frequent minor glitches, such as roads running through the edges of lakes, but there's enough good information for VFR flying.
Making changes to the environment is easier in FlightGear than in MSFS. For example, one can decrease or increase the atmospheric haze in increments, without pausing the flight, by pressing the z/Z key. Weather and time of day changes can also be made without pausing the sim, and take effect almost instantly.
THE FLYING EXPERIENCE
Of course, flying is what it is all about. The fact is I find this sim is very fun to fly. The lower degree of eye candy makes the motion very smooth. By and large, the virtual cockpits (for those models that have them) have good visibility, and the gauges are easy to read and move fluidly. Many of the planes have clickable spots in the VC, adding to the realism. If you like to fly outside of the plane, among the several outside views is a chase plane view that banks with your plane. To me this is a more exciting and immersive way to watch yourself fly. There is also a more traditional spot view that does not bank, as well as two tower views (one follows the plane, one is fixed).
To really test the flying experience, I did a fair bit of pattern
flying. For my money (so to speak), if you find it satisfying just
flying the pattern over and over again, then you have a good
simulator. FlightGear passes this test easily. When you are on final
approach, dealing with the altitude, airspeed, and power equation
while compensating for a crosswind, you feel the magic of flying.
After landing, you'll find yourself wanting to go up again and try to
do it better.
Another intriguing feature is that there are several approaches to flight modelling available in the sim. I have to confess I haven't experimented with the different options yet, so I can't say too much about this capability. Also, they have designed things so that it is much easier to tweak flight models. Practically everything about the model is configured with xml files, which you can edit if you want to fine tune the performance.
I fly mostly GA, so that's where I've spent most of my time. I've
enjoyed flying the Cessna 172, and the Piper Cherokee, and the add-on
Seneca. The Cub is fun to fly, but hard to land; it tends to float
forever. I did try out some of the military jets, as well as the
Citation II, and found them a lot of fun. The F-16 and P-51 models are
especially well done. The 737 is one of the weaker models, not even
having a 3D cockpit. However, there are more tubeliners available for
downloading from the FlightGear site.
The sloped runways are a delight to behold. Seeing them makes one realize what we've been missing all these years. I have not yet found an airport with slope significant enough to make takeoffs and landings a challenge, but I'm sure there's some out there. It's an interesting experience to release the brakes and find yourself rolling backwards!
Among the weaknesses in the flying experience is ground handling and
sound. A good landing is handled well, but a near crash can produce
unexpected results. The sound is OK, but doesn't provide as much
feedback as one might wish. For example, throttle changes are not
always detectable by ear for many of the planes. Some aircraft are
better than others in this respect, so this is not an inherent
limitation of the sim. Also, there is no collision detection with the
auto-generated scenery objects, and you might discover that you can
land just fine on water without floats.
For something completely different, try the R/C plane. This could be a valuable training tool if you ever want to fly real radio control planes, as it helps you get used to the reverse control when the model is flying towards you.
EXPANDING
Adding scenery is simple, though it does require large downloads. Each 10 by 10 degree scenery file can be as much as 100 MB or more. You will need additional software to untar the files; I recommend 7-Zip (also open source!). Directions for where to put the files are in the documentation, just be sure you let FGRun know where the files are (you need to go back to the first panel of FGRun). Adding aircraft is as simple as unzipping the main folder into the data/aircraft directory.
SUMMARY
FlightGear is a fun, feature packed flight simulation package that is good out of the box, but also open to unlimited expansion. A word of caution, though: remember that this is a work in progress, and the work of volunteers. You will run into some glitches, some quirks, and some outright bugs. Therefore, you will do well to approach this with a generous, adventurous spirit whenever you hit any obstacles. For example, I couldn't get it to work well in game mode with my ATI card (possibly the hardware or driver's fault). But I discovered that I can get it to run really well in windowed mode with a full screen option (which hides the title bar); this gives me essentially the same thing as long as I hide the Windows task bar. If you're really stumped, there is also a forum on the FlightGear web site where you can get questions answered.Finally, I would like to make a pitch to our great community of freeware add-on developers to look into FlightGear. It would be great if even just a small fraction of them put their creativity towards making more FlightGear planes and scenery.
Chris Hodge
http://simflyer.blogspot.com/
