FlightGear v2.8.0 Released

 

August 17, 2012 – FlightGear v2.8.0 is Released

The FlightGear development team is happy to announce the v2.8.0 release of FlightGear, the free, open-source flight simulator. This new version contains many exciting new features, enhancements and bugfixes.

V2.8.0 includes improvements making FlightGear world more realistic than ever before.  Placement of random buildings and trees match the underlying terrain texture, and urban areas now have denser random buildings.  Textures can be region specific, and users can select between summer and winter textures in-sim.  An improved atmospheric scattering and terrain haze model means the lighting of the terrain is more realistic.  Finally, a new automated system is now available for scenery submissions that automatically get rolled into the scenery distribution to be enjoyed by everyone.

A very exciting new addition is “Project Rembrandt”.  This is still considered experimental and not enabled by default.  This enables real-time shadows, and support for multiple light sources such as landing lights.  Even rotating beacons illuminate the surroundings correctly.

Founded in 1997, FlightGear celebrated the 15th anniversary of it’s first official release in July.  FlightGear is developed by a worldwide group of volunteers, brought together by a shared ambition to create the most realistic flight simulator possible that is free to use, modify and distribute. FlightGear is used all over the world by desktop flight simulator enthusiasts, for University research and education, for a variety of aerospace engineering and visualization work in industry, and even for interactive exhibits in museums.

FlightGear features more than 400 aircraft, a worldwide seamless scenery database, a multi-player environment, detailed sky modelling, a flexible and open aircraft modelling system, varied networking options, multiple display support, a powerful scripting language, and an open architecture. Best of all, being open-source, the simulator is owned by the community and everyone is encouraged to contribute.

Start downloading FlightGear v2.8.0 for free from http://www.flightgear.org

FlightGear – Fly Free!

 

Some of the major changes include:

AI Traffic

  • Improved aircraft models and textures.

Flight dynamics

  • FlightGear has been synced with the JSBSim project.

Environment

  • Region-specific terrain textures are used for Europe and Hawaii. Now towns in Europe look different from towns in the USA.
  • Cities and towns now look more populated due to random 3D buildings, complete with lighting at night.
  • Scenery looks more realistic due to improved placement of random objects, buildings and trees.
  • Airport signs are now rendered in 3D, with support for double-sided signs. Full apt.dat 850 syntax is supported.
  • You can now select between summer and winter scenery in-sim.

Instruments & HUDs

  • A new flexible, 2D rendering system designed for complex instruments such as CDUs, MFDs, EICAS, HUDs and other glass cockpit interfaces. Canvas allows aircraft designers to easily build complex instruments without needing specialized C++ code.

Interface

  • Support for translation of the main menu into languages other than English.
  • A Nasal API is available allowing access to Navigation and route-manager data.

Highlighted new and improved aircraft

Project infrastructure

  • Various improvements to our scenery database make it easier than ever to add, delete or update objects to the FlightGear world.
  • The new aircraft download page allows you to easily find quality aircraft, by filtering on status indications.

Visual effects

  • Improved simulation of atmospheric light scattering with terrain haze.
  • An experimental renderer, named after the famous painter Rembrandt, is included for testing purposes. The Rembrandt rendered supports multiple light sources (landing lights, instrument lights), real-time shadows and ambient occlusion across aircraft and scenery for a much more realistic visual experience.

Other

  • Additional joysticks and rudder pedals are supported out-of-the-box:
    • InterLink Elite
    • Micorosft Xbox 360 Controller
    • Qware USB
    • Saitek Cyborg X (F.L.Y. 5)
    • Saitek Pro Flight Cessna Yoke
    • Saitek Pro Flight Cessna Trim Wheel
    • Saitek Pro Flight Cessna Rudder Pedals
    • Speedlink Defender
  • A French partial translation of The FlightGear Manual is now available.

Bug fixes

  • See our bugtracker for an extensive list of the bugs fixed in this release.

Interview: Jon Berndt

Q: How long have you been involved in FlightGear?

For over ten years. I’m the development coordinator (and occasionally accused of being the BDFL) for JSBSim. It’s been just a few months more than ten years since JSBSim became the default flight model for FlightGear – although it should be said that in these days a “default” flight model has less (or no) meaning compared to back then.

Q: What are your major interests in FlightGear?

Flight dynamics and control, but I really like the whole aspect of specifying a model in XML (and other) files – a truly data-driven simulation.

Q: What project are you working on right now?

Continued development of JSBSim. There are always things to tweak. Recently, I extended the PID (Proportional-Integral-Derivative) control component in JSBSim to support some work I have been doing.

Q: What do you plan on doing in the future?

Writing more documentation. Adding more features to JSBSim as needed. And trying to get an official v1.0 release out.

Q: Are you happy with the way the FlightGear project is going?

I really enjoy seeing the progress being made in the visuals (as a spectator) – in particular I find the Rembrandt project fascinating.

Q: What do you enjoy most about developing for FlightGear?

Since JSBSim is a standalone project, there are other applications that use it such as Outerra, OpenEaagles, and others. However, FlightGear has the longest history with JSBSim and the most active developer community. It has been both enlightening and exciting to see developers stretch the limits of JSBSim, and use it within FlightGear in ways that were not foreseen previously. For instance, the P-51D that Hal Engel has been developing over the past couple of years (or more?) is very good. Also, the recently published skydiver flight model was an instance of a commercial use of FlightGear with JSBSim that resulted in code being shared with us in the spirit of the GPL. With that said, the most exciting part for me of working with the FlightGear community is seeing the very real strengths of open source development on display, and contributing to that effort.

Q: Are there any “hidden features” you have worked on in FlightGear that new users may miss?

There are many features that are not hidden, but are not known about because they are not yet part of our reference manual.

Q: What is your background in Flight Simulation?

I was graduated from the University of Minnesota (as was FlightGear Development Coordinator Curt Olson). I earned a degree in Aerospace Engineering there and in 1987 I went to work for Link Flight Simulation. I wrote the flight control simulation code for the F-16 as it was migrating from an analog control system to a digital control system. In the years following that I supported the Engineering Directorate at NASA Johnson Space Center in Houston, working with flight simulators almost continuously since then. Most recently, I went to work for Sierra Nevada Corporation to do simulation and analysis work, as well as supporting some wind tunnel testing, all for the Dream Chaser lifting body project. I have been a member of the AIAA Modeling and Simulation Technical Committee along with Bruce Jackson, author of LaRCSim.

Q: What else do you enjoy doing, besides coding in C++ late at night?

I enjoy playing acoustic guitar (fingerstyle), photography, hiking along the Colorado Front Range, playing catch/fetch with my dogs, tending to a 150 gallon saltwater aquarium, and doing various home remodeling projects. But what I really need is more sleep!

Interview: Sam Clancy

Q: How long have you been involved in FlightGear?

Actively I’ve been involved with the FlightGear project since early January 2011. Simply because my old computer (which my family had had for about 5 or 6 years prior) couldn’t run FlightGear. But after we upgraded… (insert evil laugh here)

Q: What is your forum nickname?

connect is my name.

Q: What are your major interests in FlightGear?

Flying, first of all. My life dream is to become a commercial airline pilot, hopefully somewhere in Europe. I’ve taken my very first steps towards this in real life, with my “TIF” or Training Introductory Flight, but I also believe my prior experience FlightGear, and of course my continued use of FlightGear gives me a much cheaper alternative, for the time being, to gain experience.

Q: Why is it that you are interested in flight simulation or aviation in general?

The fact that it took mankind literally thousands of years to figure out how to fly, in just a century we’ve gone from the Wright Flyer all the way to the Antonov An-225, the Airbus A380, the Boeing 747, the list is endless. I think the fact we got to the moon is pretty good to.

Q: What project are you working on right now?

I think you mean projects, in my case. I’ve actually got three on the go; all of which I am collaborating on (something I love with FlightGears community spirit). They are; the Airbus A350-900XWB in co-operation with Malik Guest (tehwarlock). The Jabiru J-170 (the aircraft I completed my “TIF” or Training Introductory Flight in) with Narendran Muraleedharan (Omega Pilot/Omega95) and Project Brisbane, perhaps the most ambitious, with Lachlan Bruce (spitfirebruce21), Drew Gibson (VH-TIT/FlightGearNZ) and Malik Guest (tehwarlock).

Q: What do you plan on doing in the future?

I actually don’t know. I just hope I can develop my skills enough to contribute something really good to the FlightGear Project.

Q: Are you happy with the way the FlightGear project is going?

Overall; yes. Having come in the days of v2.0.0 and at one stage, using 0.9.0, it’s blatantly obvious the progress that has been made in the year or so I’ve been actively involved in the community.

Q: On average, how much time do you spend working with/contributing to FlightGear?

A day? Hours. Note the plural form of the word. I don’t have a number, as I’m frankly not pedantic enough to record, but I assume it’d scare me.

Q: Which of the more recent FlightGear developments do you consider most interesting/appealing?

Thorsten’s Local/Advanced Weather; I use it everytime I fly. It’s alot nicer visually then the “Global/Simple Weather” and I think it competes with FSX and REX.

Q: What do you enjoy most about developing for FlightGear?

The satisfaction you get when something works! Maybe that’s because I’m not the most technically minded, hehe.

Vertical takeoff and landing

The Harrier in Flightgear

Author: Thorsten Renk

The VTOL concept

Quite early on in the history of jet fighter aircraft, it was realized that a main vulnerability of jets is their reliance on an airbase and a runway, targets which can comparatively easily be taken out or temporarily disabled in a war, especially as the operational range of most fighters is quite limited and hence the base has to be relatively close to the front. Vertical takeoff and landing (VTOL) ability was seen as a way to overcome this problem in the 1950s, since a VTOL fighter could operate from basically anywhere.

The problem of designing a VTOL aircraft is however obvious – such an aircraft needs a thrust to weight ratio above one to lift from the ground with thrust vector pointed downward during takeoff and pointed backward during normal flight. Early designs involved planes landing on their tail (such as the Lockheed XFV-1 or the Ryan X-13 Vertijet), but these planes were difficult to control. Other designs experimented with auxiliary, downward-pointed engines, but their extra weight was found to be impractical in a fighter jet. For a long time the only truly successful design was the Harrier family achieving VTOL due to thrust vectoring nozzles. The Lockheed Martin F-35B is expected to continue the concept of a VTOL fighter in the next millenium.

In the Harrier, the jet exhaust passes through four vectoring nozzles surrounding the center of gravity of the plane. These nozzles can be vectored from zero degrees (to the rear) up to 98 degrees (down and slightly forward for deceleration in hover flight). Since there is no airstream in hover flight across any of the control surfaces, the plane is equipped with a reaction control system with a set of extra small thrusters.

All in all, the VTOL ability comes at a price – engine maintenance is difficult (the wings have to come off), the plane is difficult to fly and pilots have described it as ‘unforgiving’ and the accident rate has been comparatively high. Nevertheless, the Harrier has been considered a successful fighter design.

Vertical takeoff

Let’s explore the Harrier in Flightgear! For any VTOL design, weight is a critical consideration. The plane will lift only if the thrust-to-weight ratio is above one, thus with a full fuel and weapons load, the plane is too heavy to lift. For this reason, whenever feasible, the plane is actually used in STOL (short takeoff and landing) mode with thrust only partially vectored down and lift provided partially by aerodynamical lift and partially by downward thrust. In this case, we’d like to do a VTOL takeoff though. With full fuel loadout and two AIM-9L missiles, the plane is still able to lift from the deck of USS Carl Vinson.

After doing my preflight checks, I vector the thrust about 83 degrees down (the Harrier sits on the gear with the nose pointed up, so if I vector 90 degrees down the plane moves backward on takeoff, which is very dangerous). After releasing the parking brakes, the thrust is slowly increased and the thrust vector corrected such that the plane doesn’t move – now thrust points exactly down. I then increase the thrust until the plane lifts from the deck (this means almost full throttle for the takeoff load), and then, a few meters above the ground vector the thrust very slightly backward to accelerate.

The Harrier has a tendency to lift the nose at this point, so I am very careful to push the nose down early on. As the plane accelerates, I vector the thrust more and more back and retract the gear, and within a few seconds the plane accelerates to above 100 kt and less and less downward thrust is needed. At around 240 kt, I vector the thrust completely back and the Harrier reacts like a normal fighter jet.

The Harrier in flight

It is important to remember to reduce thrust at this point – the Harrier has a very powerful engine due to the need to lift, but it is also a very fuel-consuming engine, and in horizontal flight with full thrust it won’t go anywhere before the tanks are empty.

Once in the air, the Harrier is a fairly typical older-generation fighter jet – it has a high roll rate, a fairly small turn radius and can climb quickly to high altitude. Lacking an afterburner, it is (despite the powerful engine) not a supersonic plane. Also, without thrust vectoring the plane doesn’t handle too well at slow airspeeds and cannot compete with swept-wing designs like the F-14b. However, thrust vectoring can be used in maneuvering to suddenly decelerate the plane by vectoring the thrust forward or to achieve a very tight turn radius.

The Harrier can also land like a conventional fighter jet, in this case vectoring the thrust about 45 degrees down acts like extra flaps – the plane slows down as the backward thrust is reduced and gets extra lift from the downward thrust component.

The current cockpit of the Flightgear Harrier could clearly use some attention, it has rather basic texturing, not all instruments are implemented and all in all it tends to be the least realistic visual element in the scene.

In flight planning, it is important to remember that unlike a conventional landing, a vertical landing involves a prolonged period of full thrust, and thus (especially during practice of the VTOL approach) about 20 to 25%% of the total fuel load should be available for the landing.

Not a helicopter

Despite some similarities to helicopter flight, it should be remembered that the Harrier is not a helicopter and reacts somewhat differently. First of all, torque generated by the main rotor is a big issue for helicopters and needs to be compensated for, but torque is absent for a jet engine – the Harrier does not in itself develop a tendency to yaw when lifting off the ground.

However, the roll stability is dramatically different in hover flight. One can think of a helicopter as the mass of the helicopter body hanging underneath the lifting rotor. Thus, when the body of the helicopter starts to roll, it has a tendency to swing like a pendulum underneath the rotor, but the roll doesn’t grow by itself. In contrast, the Harrier is a mass balanced upon a column of lifting thrust, so any roll tendency will not lead to a pendulum motion but will be self-reinforcing, and if it is not corrected will lead to an unstable condition.

An unstable situation however is worse in the Harrier than in a helicopter since a helicopter pilot has more options – since a helicopter pilot can use the cyclic control to tilt the rotor to the side and well as forward/backward (and so also fly the helicopter sideways or backward). The Harrier can vector thrust only backward or down, but not to the side, i.e. it can not easily be flown sideways and has limited control over unstable situations.

Finally, on a more prosaic note, the view down is much worse in the Harrier than in many helicopter cockpits. For all these reasons, it is safer to land with a small forward velocity (which can quickly be reduced on the ground) than to touch down actually without any forward velocity.

Vertical landing

I fly pretty much a conventional approach till about 10 miles distance to the carrier. At this point I reduce the airspeed to 250 kt and start to get flaps out. I put throttle to idle and vector the nozzles down to 90 degrees. As the plane slows down due to drag, about below 200 kt the aerodynamical lift reduces significantly and I keep increasing throttle to compensate. Below 150 kt, I extend the gear. As the carrier gets closer, I aim to reduce the airspeed to about 50 kt – since the Carrier moves with about 15 kt, that gives me some 35 kt relative motion to the carrier, enough to keep the approach stable. I vector thrust slightly forward and backward from the 90 degree position to adjust airspeed and monitor throttle to control my descent rate.

At 50 kt airspeed, there is no significant aerodynamical lift left, so the plane hovers under almost full thust slowly towards the carrier. It is important to monitor both airspeed and descent rate at this point – if the airspeed drops too much, the reduction of the small remaining lift component means that I descend too fast and get below the flight deck. In addition, in this stage of the approach wind gusts are felt quite badly and can ruin the whole approach if the plane does not have enough forward motion.

Compared to a carrier landing in the F-14b, it feels as if the Harrier approaches the flight deck centimeter by centimeter, although at this point there are about 20 kt relative motion. I keep the nose of the Harrier level with the horizon and pull it up to 8 degrees only after I am above the flightdeck – this effectively vectors thrust forward and kills my remaining airspeed, this in turn reduces lift and combined with a slight decrease in throttle lets me touch down with a forward motion of less than 10 kt, which I kill by applying brakes while I push the throttle quickly to idle to let the plane settle down firmly and avoid being thrown by a sudden gust.

As can be seen here, the Harrier rests in a slightly unusual configuration with the nose pointing upward.

Clearly, the Harrier is not one of the most detailed aircraft available in Flightgear. However, it provides a good, solid hands-on understanding of the advantages and problems of the VTOL concept. Other versions of the Harrier can be found in the Flightgear UK hangar. The above screenshots have been made with the development version of Flightgear using lightfield shading and the environment-sensitive detailed water shader.

Mountain-flying in the French Alps

Author: Thorsten Renk

Altiports

If you are up for some challenging approaches and tricky landings while you like to enjoy spectacular scenery, here is a good suggestion for a destination – try visiting the French altiports.

Altiports are small airfields for small aircraft and helicopters located high up in the mountains, often serving a ski resort. The runway is usually short and quite steeply sloped (in the case of Courchevel, the slope is a solid 18.5%), and all landings are done uphill with no go-around procedure. Since the alitports are by no means in the mountain summit region, the approaches must be done in the confined regions of a valley, which means they are usually curved and somewhat dangerous. As a rule, no navaids are available, thus altiports can only operate in good weather – all this adds up to a challenge. In fact, the History Channel program ‘Most Extreme Airports’ ranks Courchevel as the 7th most dangerous airport in the world, and once you do your first approach, you will quickly discover why.

Flying the French Alps is significantly more interesting by using the highly detailed custom scenery which is available for free under a Creative Commons Attribution-ShareAlike 3.0 here. There are six altiports in the French Alps, L’Alpe d’Huez, Courchevel, La Rosiére, Mégève, Méribel and Valloire, along with a number of airfields in the valleys. The first two of these, L’Alpe d’Huez (LFHU) and Courchevel (LFLJ), have been modelled in detail for the custom scenery and are available from the PAF team hangar here. This package also contains a detailed model of Grenoble Le Versoud Aerodrome (LFLG) which is a good place to take off for a first look at Courchevel or L’Alpe d’Huez.

Here is a picture of the layout of L’Alpe d’Huez as it appears in Flightgear:

The challenges of mountain-flying

Beginners are probably better off with a powerful turboprop STOL aircraft like the de Havilland DHC-6 ‘Twin Otter’ which has the climb rate to pull out of dangerous situations, but the real challenge is better experienced in a small aircraft like the Robin DR-400. With a constant pitch single propeller and no retractable gear, this plane is, especially when passengers and baggage are on board, seriously taxed to climb over the high mountain ridges which in many cases reach above 11.000 ft.

The fuel and payload menu item allows to adjust both the fuel level in the tanks as well as any additional weight on board. Asymmetric weight distribution in JSBSim is in fact taken into account properly, if for instance the copilot weight is reduced in flight, the plane starts to roll.

Here, a DR-400 is lined up for takeoff in Courchevel with L’Alpe d’Huez as destimation. Since the airport is at an altitude of about 6500 ft, it is important to adjust the mixture properly to the altitude in order to get the full engine power for takeoff.

Once the engine is running at full power, the brakes are released and the plane accelerates quickly down the steeply sloped runway, becoming airborn halfway. Departing from Courchevel, it becomes readily apparent why the altiport is challenging and why there is no go-around procedure available.

On the direct way, the high ridges of the Vanoise National Park with elevations well above 9000 ft have to be crossed – with the fully loaded DR-400, this is a slow climb over snow-covered mountains.

Snowcover in Flightgear can be generated by shader effects with a user-controlled snowline. Since the shader effect does not place snow on steep slopes, the outcome looks very compelling.

However, also the lower valleys during the descent to L’Alpe d’Huez have a lot to offer.

This is the final approach, aiming between rocky cliffs. At this point there is still a chance to break off.

The final moments – we are committed to a landing now. The trick is to aim low and reach the threshold in level flight, then pull up to follow the slope of the runway, let gravity develerate the plane and let it touch down softly (if you try a normal approach on a runway with such a steep slope, you will break the gear) and not throttle back engine too fast, because the plane still needs to reach the top of the runway, and once the plane comes to a halt on the slope, the engine often is not powerful enough to get it moving again.

All went well – time to enjoy the company of the other pilots and have a coffee before heading back to Courchevel.

In bad weather, things can be much worse. If the valley is cloud-filled, there is no choice but to turn back if no good view of the airport is possible early on. And in gusty crosswinds, hitting the runway just right is a challenge on its own.

The beauty of mountain flying

However, once one masters the challenges of high-altitude flight and navigating in the confines of valleys, flying the Franch Alps in nice weather is primarily a good way to see spectacular scenery. Let’s head back to Courchevel!

Here, the DR-400 accelerates down the sloped runway of L’Alpe d’Huez – going down, airplanes accelerate much faster than one is used to on level runways, so we can get airborn in just a few moments.

Leaving L’Alpe d’Huez, the village and ski resort becomes visible. The winding road up from the valley is actually a popular mountain stage of the Tour de France.

The vicinity of L’Alpe d’Huez has deep valleys, spectacular cliffs and Canyons and steep, rocky mountain faces – one can fly through the valleys or high above the mountain ridges.

Enroute to Courchevel, we leave the high ridges behind and cross to the Vanoise Park in the vicinity of Modane.

Descending again, Courchevel becomes visible (just to the left of the screenshot) while the lower valleys vanish in afternoon fog.

Final impressions

Of course, one of the must-see destinations in the vicintiy is Mt. Blanc, towering at 15.781 ft above most cloud development. Its rocky lower slopes and steep cliffs make for some really spectacular scenery, and especially at sunrise or sunset, the view from the summit is spectacular.

As the sun goes down, the last clouds light up over L’Alpe d’Huez which is to be closed over the night. High time to get back to Grenoble.

Developing Computer Vision Algorithms with FlightGear

Ocean Debris

On March 12, 2012 suspected Japanese tsunami debris was discovered washed up on the beaches of Long Beach, CA.  On March 11 a deserted fishing vessel was spotted off the coast of British Columbia; by March 24 it had drifted within 120 miles of the coastline.  For many years NOAA.gov has been monitoring an every growing area in the North Pacific dubbed the “Great Pacific Garbage Patch” that appears to be collecting and concentrating all manner of plastic debris from all over the world.  Whether you are a dedicated environmentalist, or a person that leans more towards managing and sustaining the Earth’s valuable resources indefinitely, or are simply annoyed at having to photoshop garbage out of your pristine vacation pictures; the rapidly increasing amounts of trapped ocean debris should be a concern for everyone.  How does any of this relate to the FlightGear simulator?  Please read on!

 

What is “Computer Vision?”

Computer vision is a broad field that involves processing real world images or video to try to automatically extract data or intelligence.  Applications range from identifying items or features of interest (such as facial recognition) to extracting geometry and physically locating or reconstructing the layout of a scene to manipulating images in clever or useful ways.  In many ways computer vision is a fascinating and magical   area.  We all have seen software programs that can identify every picture of our Aunt Tina on our computer after we’ve identified her face in one or two pictures.  There are computer vision systems that can track people or objects that move through a network of many camera views; computer vision systems can estimate your head orientation and even figure out what direction you are looking or what object you are looking at..  Computer vision software can recognize cars, read printed text, and scan for subtle features hidden in images — and because these programs are automated, they can run around the clock and process vast amounts of imagery.  They never get fatigued, they never get bored, and they never start day dreaming about their weekend plans.

Developing a Computer Vision Application

Writing an application to do computer vision is similar to writing any other application.  The basic cycle of edit, compile, test, repeat exists like with any other program.  Computer vision algorithms apply logical rules and procedures to the image data in consistent ways to accomplish their tasks.  There really isn’t any magic, even though the results do seem magical when they outperform the abilities or pace of a human.  However, it can be a challenge to develop some computer vision applications if you do not have good access to the kind of imagery you plan to ultimately be processing.

As you can imagine, computer vision applications must deal with huge volumes of data.  Often they process live video data from multiple cameras and that data may need to be associated with other data sources in real time — something that may not be possible to test in a lab with prerecorded video.

Imagine you are developing an application which will process aerial imagery to extract some data (i.e. facial recognition) or locate and track items of interest (i.e. a big chunk of debris in the ocean.)  It could very likely be the case that you do not have much sample video to test with.  In the case of ocean debrid, it may be that you do have video from the correct altitude or taken at the correct air speed, or with the correct camera field of view or camera angle.  However, computer programs are most efficiently developed in the lab with repeatable test data and not in the field with whatever random imagery the day offers — this can lead to a disconnect between what imagery is needed for effective testing and what imagery is available.

Hunting and Tracking Ocean Debris


For several years I have been involved with a company that develops UAV’s and remote sensing and tracking systems for marine survey and research use.  One of our primary partners is NOAA.gov.  NOAA has a keen interest in understanding, tracking, and ultimately cleaning up debris in the ocean.  With the Japanese Tsunami last year, the issue of debris accumulating in our oceans has become even more important and critical, yet there is no effective strategy available for locating and removing debris from the ocean.

A satellite can survey huge areas, but not at the detail to identify specific pieces of debris.  A manned aircraft can fly at several hundred kts and cover a wide area at a low enough altitude to spot individual pieces of debris, but there is nothing you can do when debris is located.  A ship travels very slowly and has a very narrow range of view for onboard spotters.  A ship might do 10 kts (give or take) and with binoculars a human might be able to spot debris one or two miles away — if they are looking in the right direction at the exact moment a swell lifts the debris up into view in front of the nearer swells.  The upper decks of a ship offer some height for observing debris, but swells hide objects more than they reveal them.   You have to be looking in the right direction at the right time to even have a chance to spot something.  In addition to all the other challenges of ship-board debris spotting, the rolling/pitching motion of the ship makes the use of binoculars very difficult and very fatiguing.

The following two pictures were taken seconds apart.  Can you spot the debris in the first image?  In the second? (You can click on them to see the full size version.)

  

A UAS offers numerous advantages over a human operator searching from the highest deck of a ship.  The UAS offers a much higher altitude perspective looking downward so that swells and waves can’t hide objects.  The UAS offers faster speeds to visually cover more area in the same amount of time.  The UAS can carry a variety of image sensors including IR cameras or multi-spectral cameras which offer increased ability to reliably detect certain types of objects under a variety of conditions.  Add computer vision software to process the UAV’s imagery and an effective debris location and tracking system begins to emerge.

The UAS has limited range though; and if a significant object is detected, it has no ability to tag or recover the object.  Thus it is important to combine UAV operations with a ship in the vicinity to support those UAV operations and be able to take action when something is found.

Visual Challenges of Computer Vision in a Marine Environment

 

As with any computer vision application, narrowing the scope and focus of the application as much as possible makes solving the problem easier.  Using the example of a UAV flying over the ocean and collecting imagery from a camera looking straight down, then the camera frame will always be completely filled with a straight-down view of the ocean surface.  We assume we don’t have to deal with the horizon, sky, or clouds or nearby coastline.  The result is that the ocean for the most part is some shade of blue — that is convenient.  Anything that is not blue is not ocean and then becomes highly interesting.  But despite limiting the scope of the problem in this way, the computer vision application still has to deal with several significant challenges: 1. Sun glint — the sun reflecting back at us off the water.  2. Windy days in excess of 12-15 kts produces breaking waves, foam, and even streaking (lines of foam) on the water.  Visually, sun-glint and foam impair our ability to spot objects in the water.

Why use FlightGear instead of real camera imagery?

FlightGear generates realistic views of the earth and offers complete control over the altitude, speed, camera orientation, and field of view of a simulated flight.  In addition, FlightGear can provide flight telemetry data and other data that is useful for testing or simulating real world environments.  We can also control the time of day, clouds, wind, precipitation and fly missions anywhere we like.  With FlightGear’s scripting engine, it’s possible to stage static or dynamic scenarios to create the sort of test cases we expect to be able to ultimately handle.  Of course only a small slice of computer vision applications relate to processing aerial imagery, but as UAV’s begin to attract the attention of more and more civilian and private organizations, the need for automatically processing huge volumes of imagery data will only increase.

FlightGear “Synthic Imagery” vs. real world camera imagery

 

As FlightGear continues to develop and evolve, the quality and realism of it’s graphics also are improving.  In the most recent version we have taken significant strides forward in drawing realistic ocean scenes that include accurate coloring, accurate rendering of different sea states and types of waves, very realistic sun glint, realistic sea foam (the result of breaking waves on windy days), and even rolling wake and foam created by large ships.  The quality of FlightGear ocean scenes can now (in many cases) make them almost indistinguishable from real camera imagery.

What is OpenCV?

OpenCV is a library of data structures and functions that offers most basic image processing tasks, as well as many of the more common advanced functions.  OpenCV provides the building blocks a developer needs in order to start writing a computer vision application.  OpenCV runs on Linux, Windows, Mac, and even Android.

How to connect an image processing application to FlightGear in “real time”.

Disclaimer: the nuts and bolts that I explain in this section are focused on the Linux platform.  These same tools are likely available on other platforms and may be leveraged in the same (or similar) ways to accomplish the same thing — but outside Linux your mileage may vary as they say.

I know how to capture a portion of my desktop as a movie and save it to a file.  My computer vision application knows how to read a movie file and process it frame by frame.  What is missing is that I want to be able to do this in real time without having to fly and save the video and the process it later.  My basic strategy is to first create a unix file system “fifo”, then write the captured video to this fifo, and simultaneously read from the other end of the fifo into my computer vision application.

  1.  Start FlightGear at your simulated camera resolution.  I have a cheap web cam that does basic vga (640×480) video, so using that as my “standard” I can run: “fgfs –geometry=640×480” to launch flightgear with the correct window size.  Next I drag the FlightGear window into the upper left corner of my screen so it is in a known location.
  2. Make your fifo if it doesn’t already exist.  For instance: “mkfifo /tmp/ffmpeg-fifo.avi”
  3. Start up the computer vision application:  “my-vision-app –infile /tmp/ffmpeg-fifo.avi”
  4. Start up the ffmpeg desktop movie capture utility (I have a little script I setup so I don’t have to remember all these options every time):  “ffmpeg -f alsa -i default -f x11grab -s 640×480 -r 15 -b 200k -bf 2 -g 300 -i :0.0+1,58 -ar 22050 -ab 128k -acodec libmp3lame -vcodec mjpeg -sameq -y /tmp/ffmpeg-fifo.avi”

That’s all it takes and the computer vision application is up and processing live FlightGear generated imagery.  One thing I discovered with fifo’s.: it seems to work best to start the reader (the CV app) before starting the writer (ffmpeg).  This way the buffers don’t fill up and cause delays.

Results

Here is a snapshot of the anomaly detection and tracking in action:

The original image:

The image partitioned into water vs. not-water.

Dilating the mask (connects the noisy dots):

Eroding the dilated mask (to shink it back to approximately the original size and location in the image):

The final composite image showing the detected blob on top of the original frame:

Lastly, here is a youtube video showing all the pieces working together.  In FlightGear: I have created a random debris field scattered across an area of open  ocean about 6nm x  6nm.  I have added a downward looking camera to my test aircraft.  Then I built a route that flew several “transacts” (straight line paths) through the debris field.  I used the above mentioned procedure to feed the live FlightGear imagery into my computer vision algorithm that detects and tracks anomalies.  The debris you tend to see from the air looks very small — usually just a few pixels at best in your image, so the algorithm needs careful tuning to avoid false positives and missing objects.

Please watch this video in full screen resolution so you can see the specks of debris and the tracking algorithm in action!

Interview: Christian Schmitt

Q: What is your forum/IRC nickname?

Surprise: it’s papillon81. Yes, I’m that guy 🙂

Q: How long have you been involved in FlightGear?

Acording to my mail correspondence it must have been in 2007/2008 when I became an active part. I was unsatisfied with the state of EDDF in the FG scenery (no buildings, lightpoles everywhere), so I teamed up with a guy who had already started some work there. I ended up creating all of the terminal buildings and improving the airport layout. In those days, not many pilots were flying there. This changed in the months afterwards, which was a big boost of motivation, too.

Q: What are your major interests in FlightGear?

My main interest is clearly the scenery and technology connected with it, like GIS. I started to create some custom scenery, like Helgoland, and after I was granted direct access to the mapserver database, I was able to proxy-commit other peoples work, that started to come in. IMHO, the best FDM or aircraft models are useless if you don’t have a nice place to fly, takeoff and land 🙂 So this area is what motivates me the most.

I do also maintain the Gentoo packages (ebuilds) for the GIT versions of FG, SG and TerraGear. All these can be found in the Gentoo Gamerlay repo.

Q: What project are you working on right now?

Some months ago I was fed up of FG being unable to read apt.dat 850 data. So I started digging into the terragear code. Having no experience with C++, it was a steep learning curve, but to my own surprise I was able to convert the original TG parser to read the runway data and other features from the new format files. I started to implement as many features I was able to. Luckily, Pete was already working on the taxiways and surface features. So we teamed up and eventually merged our work together. Since then it has become a really great project to learn and improve FG along the way for me. I hope it will be put into use for the next scenery version. Before that can happen, we need more testers and bug reports (hint! hint! hint!) 🙂

Q: What do you plan on doing in the future?

I will continue to work on Terragear, commit some improvements to the Concorde (my favorite plane in FG) and take care of merge requests. I’d also like to dive more into the FG/SG code and do some adjustments here and there. We’ll see what else the future might bring 🙂

Q: Are you happy with the way the FlightGear project is going?

I’m actually very happy with it. The improvements from 2 years ago up to now are breathtaking. Sometimes it is just amazing what features people start to work on, like Project Rembrandt right now. Also, the work that went into the weather and shader system recently is amazing.

Q: What do you enjoy most about developing for FlightGear?

The fact that we support each other and have a strong community with many very capable people from completely different backgrounds. Knowing that you can build on the work of others and that there is a helping hand in case of problems. Personally I like the FG IRC channel a lot.

Q: What advice can you give to new developers who want to get started on their first aircraft/new feature/Nasal script?

They should first of all have some experience with FG in general, meaning, they should have used the program for some time. We often have people asking questions that they could answer for themselves just by USING FG a bit with different aircraft for a bit longer than just a day or so. If they identify an area where they want to start developing, they should get in contact with the maintainer(s) and seek advice before investing many hours of work.

Advanced Weather v1.4 in Flightgear 2.6+

Part I: Convective clouds

Author: Thorsten Renk

The screenshots shown in the following use shaders, textures and scenery which are for various reasons (incompatible license, too recent development,…) not part of the official Flightgear 2.6 release. However, these are available for download and every feature works with Flightgear 2.6. The following packages need to be installed in addition to get to see the same: lightfield shader package v1.1, Juneau custom scenery, and textures from regional textures v0.1.

An integrated weather system

Without a doubt, clouds, haze and fog are the most easily noticed features of weather in a flight simulation, followed by winds. Advanced Weather v1.4 is however more than a tool to draw clouds and set wind parameters – it is a system with a (limited) understanding what the weather which it currently tries to render is, and it aims to simulate features of atmospheric physics.

This means that different weather phenomena tie together – winds and terrain influence the way cloud formation is taking place, cloud formation and the formation of thermal updrafts is connected, and weather is always understood as part of a large-scale weather pattern involving high and low pressure systems.

At the same time, clouds and atmospheric haze also influence the atmospheric light (and now also the scenery) in an essential way – strong fogging changes the color of sunrises to a blue-grey, wave patterns on the ocean follow the wind strength and direction and rain causes visibly wet runways. Let us have a look at how this works in fair weather.

The formation of convective clouds

Fair weather is typically characterized by convective cloud development: The sun heats the terrain and the air layer just above, thus warm air rises up in ‘bubbles’ and forms thermals, as the air rises, it expands and cools and eventually the moisture condenses into droplets, forming the characteristic, cauliflower-shaped Cumulus clouds. Cumulus clouds are the most common example of clouds formed by pronounced vertical motion of air.

As every glider pilot looking for thermals has to learn quickly, the formation of convective clouds depends on many different factors. The terrain type is crucial – while rock or concrete surfaces heat well in sunshine and may easily lead to well-developed thermals and cloud formation, open water or ice is much less likely to heat up in sunshine and seed Cumulus formation. High points in the terrain mark the spots where the bubbles of warm air are most likely to lift off the ground. Another important factor is the time of the day: The sun needs sufficient time to heat the terrain, therefore Cumulus formation is densest around noon, but the thermal updrafts are strongest in the afternoon, and while pronounced Cumulus clouds are unlikely to form in the morning, the thermal energy accumulated over a day may still give rise to well-developed clouds in the evening.

Let’s follow the development of convective clouds during a day in Juneau (Alaska). At sunrise, only very few clouds form, and they are transient, whispy phenomena (click to enlarge images):

Later in the day, the cloud formation is somewhat stronger. Note how clouds tend to form over mountain peaks, but do not form over open water. Also, no strong cloud development occurs over Taku glacier in the upper left, despite its high altitude, as the ice surface does not heat well in the sun.

At noon, the thermal updrafts become stronger and consequently the clouds become more well-defined. While in the morning the upward motion of air rarely exceeds 0.5 m/s, around noon this becomes rather 1 m/s, to strengthen even more in the afternoon.

Yet a few hours later, the number of clouds decreases again as the thermal irradiation by the sun weakens, but then typically fewer but stronger thermals with larger cap clouds are found.

Towards sunset, there is still significant thermal energy left to lead to sizeable cloud development, although the number of clouds as well as the typical strength of thermals is decreasing again. During the night, the development of convective clouds breaks more or less down completely as there is no thermal energy from the sun available.

Interaction of convective clouds, wind and the terrain

Wind meeting a terrain barrier corresponds to an upward-moving airflow, and hence is able to alter the development pattern of convective clouds in an essential way. Consider the following scene above Maui (Hawaii) in the absence of winds. Clouds rim the peak of Haleakala, but do not actually reach all the way up to the mountaintop (note also that due to the different latitude of Hawaii, there is far more thermal energy coming from the sun than in Juneau, leading to a much higher overall density of clouds):

With 20 kt winds coming from the north, the picture changes quite drastically: clouds are now pushed up all the way to the summit of Haleakala by the rising air, whereas the falling air south of the crater creates a lee effect in which convective clouds disappear. The vegetation pattern of Maui reflects these prevaling conditions – while moist air is carried up all the way to the summit of Haleakala, it rains off and irrigates the northern slopes of the mountain, leading to a bright green forest belt. The southern slopes on the other hand see typically falling air and dissolving clouds, and are consequently much drier.

Convective clouds in flight

If the appropriate option is selected, thermals are automatically generated along with Cumulus clouds so that thermal soaring is possible. Combined with the effect of ridge lift, this can make for rather realistic mountain soaring conditions in which a good degree of skill is required to stay in the air.

But the detailed interplay between convection and the terrain leads to interesting scenes also in other planes. Around noon, the peaks of high mountains are often covered in rather dramatic clouds piling up against the slopes.

Further down, the altitude of the cloudbase is no longer determined by the terrain but by the air layers.

And yet, the terrain elevation and the change between land and water imprint a pronounced pattern onto the distribution of density, shape and size of convective clouds.

Convection may also occur due to vertical instabilities in upper air layers, leading to the development of Altocumulus clouds, or at even higher altitudes Cirrocumulus clouds. Here’s an example of the development of Altocumulus fields at 15.000 ft. At such high altitudes, the clouds are no longer influenced by the terrain underneath, but rather by the properties of the air layers between which the Altocumuli form. For instance, Altocumulus development may be caused by the instabilities associated with an approaching cold front, and may thus signal the danger of severe thunderstorms in the near future. The Advanced Weather offline weather generation automatically includes this and other rules of large-scale weather patterns.

Next: Layered clouds, haze, fog and precipitation

FlightGear v2.6.0 Released

Also available in: NederlandsEspañolFrançaisPortuguêsRomână

 

The FlightGear development team is happy to announce the v2.6.0 release of FlightGear, the free, open-source flight simulator. This new version contains many exciting new features, enhancements and bugfixes. Major improvements from v2.4.0 include reduced AI aircraft load times, easier graphics tuning, more sophisticated AI aircraft and improved usability.

Founded in 1997, FlightGear is developed by a worldwide group of volunteers, brought together by a shared ambition to create the most realistic flight simulator possible that is free to use, modify and distribute. FlightGear is used all over the world by desktop flight simulator enthusiasts, for research in Universities and for interactive exhibits in museums.

FlightGear features more than 400 aircraft, a worldwide scenery database, a worldwide multi-player environment, detailed sky modelling, a flexible and open aircraft modelling system, varied networking options, multiple display support, a powerful scripting language and an open architecture. Best of all, being open-source, the simulator is owned by the community and everyone is encouraged to contribute.

Start downloading FlightGear v2.6.0 for free from FlightGear.org

FlightGear – Fly Free!

Some of the major changes include:

Aircraft operations:

  • At selected airports, FlightGear can automatically start at an appropriate parking spot based on the size and type of your aircraft.
  • At airports which support this feature, a visual display of the taxi route on the ground guides you to the active runway, while following the correct taxiways.

AI system

  • To reduce stuttering during model loading and take further advantage of multi-core CPUs, MP and AI aircraft models are now loaded in a background thread.
  • To reduce load times still further, only the parts of the aircraft currently visible are loaded from disk.
  • AI and multiplayer aircraft are no longer silent objects, they can produce sounds just like the main aircraft.

AI Traffic

  • Many new and updated AI aircraft and liveries. Over 80 airlines now populate the virtual skies.
  • The range at which AI aircraft are displayed is now configurable, allowing you to tune FlightGear for best performance.
  • AI controlled pilots have received extensive landing training and now make a more realistic approach and vacate the runway when able.
  • The simulator now assigns an available parking position on startup.

Flight dynamics

  • The JSBSim flight dynamics model received a major overhaul.

Environment

  • The Local Weather package has been further integrated with the FlightGear core, and has been renamed “Advanced Weather”. New rendering techniques allow more detailed clouds with no performance impact. High altitude clouds are rendered more realistically, and clouds move with the wind without impacting performance.

Interface

  • New replay system. Video-player like controls, including slow motion and fast forward. Pilots can now take over the aircraft at any time during a replay. Great for training particular flight phases such as approach over and over again.
  • Aircraft status ratings are displayed in the FlightGear launcher, allowing you to see at a glance the FDM, model, systems and cockpit quality for rated aircraft.
  • Multiplayer settings can be accessed in-sim. You can now choose your callsign, select an MP server and connect within the simulator.
  • Automatic scenery download is now even easier to use. Simply select the scenery directory to download to, and switch it on.
  • Individual graphics effects can now be configured from within the Rendering Settings dialog, allowing you to fine-tune the performance of FlightGear within the sim.
  • The simulation of radio signal propagation has started and will make the reception of ATC messages and navigation aids more realistic in the future.
  • A new set of options makes it easier to create seamless and zoomable multi screen setups.
  • A new performance monitor shows the time spent in each subsystem.

Highlighted new and improved aircraft

Project infrastructure

  • CMake is now the official build system on Linux, Mac and Windows.

Visual effects

  • The sea now looks more realistic. Waves align with the wind, and foam appears at high wind speed.
  • Steep slopes now appear rocky.
  • Runways now appear wet during rain showers.
  • To help aircraft developers, a single shader combining bump-map, specular, reflection and light mapping components is now available.

Other

  • Additional joysticks and rudder pedals are supported out-of-the-box, including the Logitech WingMan Interceptor, Saitek Pro Combat Rudder Pedals and Thrustmaster HOTAS Warthog.
  • FGPanel, lightweight software to render 2D instrument panels, is now included as part of the release.

Bug fixes

  • See our bugtracker for an extensive list of the bugs fixed in this release.

Windows

  • 64bit version restored and its installation integrated in the main fgsetup installer

Sky Diving Visualization

The Challenge

As a skydiver adds more gear such as front packs and items strapped to legs or arms, the jumper’s basic stability in free-fall is reduced.  It becomes easier to tumble out of control and there is less margin for error.  Similarly, the aerodynamic wake of the jumper may interfere with pilot chute opening (known as “hesitation”). Investigating different gear configurations generally involves vertical wind tunnel testing, or actual tests with jumpers. To avoid some of the cost, and mitigating safety concerns, a tool to computationally analyze these jumpers and their gear is highly desired. Creare, Inc., an R+D research firm in Hanover, NH, under funding from the US Army, developed a Computation Fluid Dynamics toolkit for analyzing jumpers and their equipment, and model the resulting configurations in FlightGear.

Note: a flyable parachutist model is available to download and test at the end of this article.

Fluent (CFD) and Stability Derivatives

CFD = Computational Fluid Dynamics.  ANSYS Fluent is a high end CFD that models flow, turbulence, and heat transfer in 3d.   Imagine being able to take a 3d model of a sky diver (or an aircraft) and place it at different orientations and different poses.  Then for each orientation and pose, run a computer simulation of exactly how the air flows around the sky diver, where pockets of turbulence are generated, and what forces and moments are produced.  Imagine all the combinations of roll and pitch and body poses possible — it leads to a huge number of combinations.  Now imagine repeating that for several different arrangements of front and back packs and other equipment.  You will need a cluster of computers running for days or even weeks to compute all the permutations just for a single pack configuration.  This is essentially a “virtual wind tunnel” running on a super computer cluster of PC’s.

In the case of the parachutist simulation: the amount of computation time required to generate 2 scenarios (with a back pack and without) was approximately 25,000 cpu-hours — or around 2 years of compute time on a single processor PC.  1000 individual simulations were run, each involving approximately 4 million “elements”.

One of the detailed CFD models used by Creare

 

Validation

Real world testing and data collection was performed in a vertical wind tunnel (such as the one linked here.)  This real world data could then be compared to the the Fluent (CFD) results to validate and possibly improve the computer model.

Real Time Simulation

Build-Up of Coefficients:

  • For each component of the model, the local angle of attack and sideslip angle are calculated from the combination of the limb orientation and the overall angle of attack and sideslip of the entire model.
  • For each of the six degrees of freedom, the contribution of the model component to the overall aerodynamic response is calculated from tables of non-dimensional coefficients:
    CFx,y,z = Fx,y,z / ( q * Acomp )
    CMx,y,z = Mx,y,z / ( q * Acomp * Lcomp )
  • The two-dimensional lookup tables are compiled from data extracted from the CFD results in the Solution Database.

Forces and Moments:

  • Aerodynamic forces and moments are transformed from the local frame to the global frame and then summed.
  • Resultant forces and moments then determine accelerations, velocity and turn rates are calculated, and the model iterates.

Creare partnered with Jon Berndt (the founder of JSBSim–one of the core physics engines used by FlightGear) to contribute some clever additions to JSBSim that permit a “blade element” approach to parachutist modeling.  Jon helped tremendously optimizing and integrating the required new code into JSBSim which then ultimately led to its inclusion in FlightGear.  The parachutist physics model is an order of magnitude more complex than a typical aircraft model.

Figure Animation and Posing

The character model is built out of several animated subcomponents: left & right forearms, left & right upper arms, left & right lower legs, left & right upper legs, head, torso, and pelvis.  The model parts are attached in a cascading fashion like a real figure, and each joint can be rotated through all 3 axis (roll, pitch, and yaw.)  In order to avoid unrealistic contortions, sensible joint range of motions are defined.

There are a number of predefined poses where the appropriate joint angles have all been worked out in advance.

  • Box: a neutral pose minimizing rotational or translational motion.
  • Left & Right Translation: mirrored poses that induce a “slide” either to the left or right.
  • Anterior Translation: a pose that induces a forward slide.
  • Posterior Translation: a pose that induces a rearward slide.
  • Left & Right Dorsoventral: mirrored poses that induce a left or right rotation (yaw.)
  • Dorsal: a “spread eagle” pose that maximizes surface area and thus minimizes decent rate.
  • Ventral: a “compressed” pose that minimizes surface area thus maximizes decent rate.
You might notice that these poses map rather neatly into well understood pilot controls similar to flying a helicopter.  For the FlightGear simulation we can mix these poses together in proportion to the corresponding joystick axis deflection and throttle position and fly the sky-diver intuitively.  For those that doubt, this actually works quite well! 🙂

Visualizing CFD Flow-lines

One of the neat things that a CFD analysis can produce are airflow lines that pass around the model.  We can take the 3d flowlines that are produced by the CFD and attach them to the 3d model of the figure.  This allows visualizing the flow lines from any FlightGear perspective.  One interesting technical challenge is that the flow lines need to keep a fixed vertical orientation even though the model may roll or pitch, yet the flowlines must track the heading/yaw of the model.  This can be done by setting up appropriate inverse transformations in the FlightGear model animation configuration file.

Smoke and Trajectory Markers

FlightGear offers additional visualization aids.  The model is set up to support emitting smoke.  FlightGear smoke drifts with the prevaling winds (which can often be substantial at higher altitudes.)  The model is also setup to emit “trajectory markers” at a fixed rate.  The trajectory markers stay fixed in 3d space and represent the actual path the sky diver follows.  In addition they represent the orientation of the sky diver at that point in space.

Where is the Parachute?

This exercise is setup as a free-fall simulation, not a parachute simulation so there is no chute modeled.  Instead the simulation is mercifully paused when the altitude reaches 100′ above the surface.

Download and Fly

Follow these instructions to download, install, and fly the Creare Parachutist model:

  • Note: the parachutist model is not compatible with FlightGear v2.4, you must fly this model with one of the v2.6 release candidates, or the official v2.6 release scheduled for February 17.
  • Download the Creare_Parachutist-v1.0.zip file.
  • Unzip it into your FlightGear “Aircraft” folder.
  • Start FlightGear and select either –aircraft=Parachutist-Scenario1 or –aircraft=Parachutist-Scenario2
  • Make sure you specify  an initial altitude (such as –altitude=10000), otherwise you will just be sitting at the end of the runway working on your tan.
  • Press F1 and F2 to toggle the two available dialog boxes on/off.
  • You can manipulate the joint poses individually or select from a set of pre-defined poses, or select “Joystick” control and fly with a joystick (or keyboard or mouse) similar to flying a helicopter or airplane.

Credits

  • Dietz, A. J., Kaszeta, R. W., Cameron, B., Micka, D. J., Deserranno, D. and Craley, J.”A CFD Toolkit for Modeling Parachutists in Freefall”, presented at the 21st AIAA Decelerators Conference in Dublin, Ireland, 23-26 May 2011. Paper AIAA 2011-2589.
  • The Creare Freefalling Parachutist model was developed by Anthony Dietz (Principal Investigator), Richard Kaszeta , Benjamin Cameron, Daniel Micka, and Dimitri Deserranno of Creare, Inc., as part of an SBIR Phase II project sponsored by the U.S. Army RDECOM Acquisition Center under Contract No. W91CRB-08-C-0135. Additional contributions we made by Curt Olson and Jon S. Berndt as consultants. The resulting parachutist model is unvalidated and therefore, should not be used other than for demonstration purposes. Any opinions, findings and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the US Army RDECOM Acquisition Center.  Due to the significant contributions made to the project by several open source developers,  Creare has released a version of the resulting parachutist model to the open source community for continued development and use.  The FFTK itself continues development as a proprietary Creare project. For information on the FFTK itself, please contact Richard Kaszeta at rwk@creare.com, or 603-643-3800.
  • Flightgear modeling, animation, and scripting – Curtis L. Olson