Matt, what were your reasons for deciding to create a flight simulator for the mobile market?

Infinite Flight was initially started from a side project I had been working on for many years. When Microsoft decided to cancel the Flight Simulator franchise, I was working in Silicon Valley for a popular graphics card company. One of my colleagues and good friend (Philippe) and I decided that the timing was right to enter the market and join forces to create a new flight simulator based around my original flight model. After a few weeks, we quickly realized that while it would take years for us to reach the same level as existing simulators available on the desktop, we could create a minimum viable product for the mobile market. This product could then (theoretically) be updated frequently (based on community feedback) so as to build something competitive.

About 6 months later, we shipped our first version: Windows Phone in 2011, iOS in 2012, and a year later on Android/Amazon.

To summarize, it's not something that was decided in one day, it's more of an organic chain of events that made us go from a standalone hobby flight sim to a commercial mobile app.

Tell us about your products and what you feel are its strongest and most fun features for the end user.

Infinite Flight features dozens of airplanes, ranging from the Cessna 172 or Cirrus SR22 to large airliners like the Airbus A380, Boeing 777, as well as fighters, warbirds, and more. It has many flyable areas with hundreds of airports (full taxiway layouts), weather configuration, autopilot, flight planning, realistic flight physics, multiple camera views, extremely functional controls, time of day settings, replay system, and much much more. We also recently added a new multiplayer mode, we call it Infinite Flight Live. It's a world where all pilots connect and fly together with radio, real time weather, etc.

The target audience is very wide as we've received feedback from students, real world GA and airline pilots, retirees and professionals; so quite a broad spectrum.

In terms of strongest features, I'd say it is a mix of flight physics, detailed airplane models and our new Live (multiplayer) feature, the latter being the strongest one. Infinite Flight Live opened up a whole new world of possibilities and reinforced our commitment to community engagement.

There's an extremely active community of fans on several Facebook groups, and these guys organize daily events and fly-ins in Live with different themes. We're going to reinforce this in our next update with more features for Live, including Live ATC where users will be able to act as ATC controllers for tower/ground/approach, etc. To give you an idea, it will be something similar to what is already available on IVAO/VATSIM. We've been beta testing this for a few months and all the testers love it!

We also organize official weekly events, with different themes each time. This brings a lot of pilots together (think half hour queues before take off at KLAX).

How is beta testing implemented at Infinite Flight? Is it open to the public, or do you have a set team?

We have a core team of private beta testers; these include passionate users we've recruited over a period of time. Occasionally we do have open public betas. In fact, we actually have a semi open beta right now for the new ATC features we're incorporating. We couldn't really use the production server since the changes we made broke compatibility. Because of this, we opened a semi public beta. We do however filter the types of users we accept in this group. We need people that can help us find bugs, not give us more work if you know what I mean.

What would you say the biggest challenge is when it comes to developing for the mobile market?

The biggest challenge is the hardware. For two reasons; first, because even if mobile processors are getting more powerful each year, we still have to deal with a wide variety of device configurations. The second challenge we face is mostly related to Android. Some vendors release way too many mobile devices into the market without paying much attention to the graphics drivers they ship with them. This can lead to rendering problems that are hard to diagnose and fix, especially if this is happening on some obscure phone that only ships in one country.

Is Infinite Flight purely for entertainment purposes or can people who are interested in serious flight learn things from it?

I like to describe Infinite Flight as a serious simulator game. It's classified as a game because we really have no other choice in today's mobile market to gain any kind of visibility. However, you can't give this app to a 5 year old and expect that they are going to have fun. A slight interest in aviation is a prerequisite to fully enjoy Infinite Flight.

To create the realism that Infinite Flight now offers, it meant working with airline pilots and aviation experts. This ensured that the latest flight models are as accurate as possible. The 737 is one of our most accurate models to date. Set the weight, flaps configuration, airspeed and you'll be right where the real 737 would be in real life!

We even support things like density altitude, so if you take your Cessna 172 with four people to a place like Aspen on a hot day, you'll have trouble getting off the ground (due to the environmental modeling in the sim).

Infinite Flight also supports complex flight planning as well as ILS approaches. You can just input any approach in the sim and practice it before you go fly. So we're in the games section in much the same way FSX was, but we're just as serious as they were in terms of simulation accuracy.

What advantages do you see a mobile flight simulator having over its PC counterpart?

Ease of use is one; there's no need to build an expensive rig and spend hours trying to figure out why the frame rate won't go over 10 fps.

Ease of access is another, as you don't have to go into your office or bedroom to get your flight sim fix! You can be on your couch and when you feel like taking to the air, pop your iPad out and start flying! Why, you don't even have to be at home for that matter. We've got many shots of Infinite Flight being used in by passengers during commercial flights, even in the cockpit by the crew...on downtime that is!

Another important factor is that mobile flight simulators are definitely cheaper (hardware and software) than their PC counterparts. While it's not an issue for someone who has a steady income, many students and kids (who want to enjoy flight simulation) rarely have the budget to build a custom PC, so purchasing a two year old iPad to play Infinite Flight becomes a viable and realistic option.

Matt, does the mobile environment limit or constrain you with regards to what ideas you can implement?

It does but it's getting better! Originally we were limited to devices like the iPod Touch 4th Gen, which had 256MB of memory and an extremely weak CPU/GPU combo, but as of today (only a few years later), we're running on multicore processors and covering both Android and iOS. The iPad Air 2 for example runs Infinite Flight extremely well, which means that we can definitely step things up a notch.

That being said, we always try to be careful when adding new features. It's important to us to not exclude users with older devices. This is why we provide fallbacks whenever possible.

What would you say are the major differences between Infinite Flight and X-Plane Mobile (which it is often compared to)?

I'd say our key strengths are our detailed airplanes, the flight model, the flight planning and replay features, our camera options and general control layout. The Live Multiplayer feature is also one major difference.

Matt, could you tell us a bit more about the physics engine of Infinite Flight?

Sure. The physics engine is based on a third party physics library that handles the basic functionality of having groups of objects, in the form of an airplane with wheels attached to it, that sits on the ground.

Without the flight model math, if you set this object 1000 feet above the ground, it'll just fall back towards the earth and crash.

What we do is take care of the magic that makes the airplane fly, based on things such as airspeed, angle of attack and airplane weight, etc.

About 30 times per second, the physics engine figures out what the relative wind velocity is from several points along each wing. It then computes the angle of attack from the data it receives. From this angle, it uses a lookup table to get the lift coefficient that corresponds to the AOA. Once done, it computes the force, and applies this force on the wing (meaning, it will apply a force at each point). It then adds all the types of drag (lift induced, parasitic, etc.). Once the physics engine has moved the airplane, we do the same thing over again.

We also take many other variables into consideration during the lift equation such as the temperature, air density, humidity, etc.

We're often asked to compare Infinite Flight to other sims, and whilst always subjective, I think our model is actually pretty accurate. Of course there's always room for improvement, especially during the more 'chaotic' periods of flight (spins, unusual attitudes, etc.) but overall, the model is pretty configurable, and with each new release, only gets better.

The advantage that we have over other sims on the market is our use of lift curves. While some might say that inferring the lift data from wing shape is better, it's not necessarily true. You always end up cutting corners, there's always approximations, especially in stalled situations. This is where the curves help since you can fine tune the values for each section of the wing so as to make it match real world behavior.

Tweaking airplane flight models takes about a month of on and off work. There's a lot of trial and error, and lots of back and forth with the beta test guys as we have to gather a lot of documentation on the airplanes, performance data, manuals, etc.

A big chunk of that time is also spent configuring the autopilot, which is a highly complex system to tune. If I'm honest, it's actually my least favorite part! The difficulty in AP tuning is that we're actually making the airplane fly. What I mean by this, is that we're not putting it on a rail and telling the model where to go, we're actually moving the control surfaces, just like you would if you were in control. Believe it or not, keeping an airplane level at different speeds (with various flap settings) is not an easy task. There's no one set of parameters we can use for each airplane as each one uses its own custom set of parameters.

Matt, could you tell us about the new multiplayer feature?

The multiplayer feature has been in the sim since September. It's not a one-on-one multiplayer, but sort of an MMO flight sim, if you will. We've started with players in the same world, communicating in an FSX style, text based Unicom system, and our next update will bring a new way for users to act as Air Traffic Controllers. We're being careful with this though as we're definitely not going to allow everyone to have access to controller positions.

Our beta testing has revealed that a good pilot isn't necessarily a good controller as it's an entirely different set of skills being used. Being vectored for an ILS approach by a controller that's not up to scratch is frustrating for all those involved and something we'd like to avoid.

Testing so far has been extremely positive, especially ILS approaches. We're really excited about this new feature and we can't wait for people to try it. It should make our fly-ins much more fun and organized.

OSM data is now being widely used in the generation of scenery, so will/could Infinite Flight incorporate this in future releases?

We actually use OSM data already as the water bodies are imported straight from OSM. We've also conducted some experiments with roads and buildings. The pipeline to process all these things is there, we just need ways to render all these features efficiently on a mobile environment.

Knowing how popular Infinite Flight is, have you ever considered porting it across to the PC/MAC?

Of course. Since we started development on a PC, we've actually never stopped maintaining the PC version. Most of our development is done on PC, which is then shipped over to the mobile version. There's very little code that is specific to each platform, as most of it is shared.

However, shipping Infinite Flight to the PC brings with it its own set of problems; graphics drivers, joystick configurations, etc. All this would would take time to iron out, but we definitely plan to bring Infinite Flight to PC at some point in time. Being a small team of only three developers, we have to prioritize.

Only three developers? Matt, could you tell us what each member's role is?

Yep, only three, that cuts the time we spend in meetings!

Matt

Philippe

In the team, we've got:

• Philippe: He takes care of low level graphics rendering, optimizations, platform code, the sound system, the content pipeline (compiling and optimizing the things we render) and the terrain and airport rendering.
• RgBa: (it's a pseudonym, this guy is very secretive about his name). He takes care of graphics effects and various other aspects of the rendering engine. He worked on our outstanding and new water rendering, also airplane rendering and he's now working on smoke effects, fog and other awesome new graphics options.
• Matt: I work on airplane physics, the flight model, aviation related things (maps, flight planning...), the user interface, multiplayer/Live/database.

Would you ever consider allowing community content (scenery/aircraft) to be added to the simulator in the future releases?

That's something we're planning on, yes. The issue with mobile is that it's hard to upload user content on those devices, especially on iOS. We might have to rely on other methods to get the content there, maybe something like DropBox or other storage systems.

What exciting features do you have planned for the future (which you can tell us about)?

We have many things in the pipeline; buildings, better weather system, getting rid of regions to allow worldwide flights. One thing I can tell you for certain is that our next plane will be the most detailed we've done yet. It's in the process of being built, and it's going to be in orders of magnitude better than anything we've shipped so far!

Links:

We're heavily feedback based, so we've got a site where users can request new features and vote on existing ones. It's proven to be very useful in the past as it enables us to figure out what the community needs:

feedback.flyingdevstudio.com

We're also very active on social media:

twitter@flyingdevstudio

https://www.facebook.com/infiniteflightapp

The most active Facebook Group of fans is Infinite Flight Fan Group

www.facebook.com/groups/infiniteflightfangroup (they have about 11,000 members and growing.

It's an extremely active community!

YouTube Link: