Building A Recreational Flight Simulator

Progress summary

514 manuscript pages of 608 planned.

Book overview

This is to be a broad ranging introduction to building a flight simulator for recreational use. It will touch upon most aspects of simulator building. 

Most chapters will contain these sections:

Because the focus is on recreational rather than training simulators, a common thread will be improving the flight simulation experience rather than building a picture perfect training device. Each topic will be presented in terms of what it can do to enhance the illusion of flight and deepen the sense of immersion. This provides a means for prioritizing where one’s time and hard earned cash will be going.

The book is intended for hobbyists, so I’m offering a strong hands-on approach for the reader. There will be a lot of projects, both large and small. However, even the most enthusiastic DIY-er, will occasionally want to buy rather than build. I feel it is important to present at least some information about purchase options. (From other vendors, not me!) This is something of a risk. Our hobby is small and does not support many vendors. Frequently, new vendors learn the hard way and vanish overnight. Portions of the book might rapidly go out of date. Nonetheless, making the reader aware of options other than building seems valuable.

I’ve been working on the book long enough to have a pretty good idea of what should be in it. I’ve chosen what I believe to be a good balance of breadth and depth. I’ve outlined my planned approach below.

I am very much open to comments, observations, criticism and suggestions. If you see shortcomings in what I’ve outlined, please drop me a note at  "book2comments" (at) "mikesflightdeck.com".

Thanks. 

Introduction

This not only introduces the book’s structure, but also makes the case for building a home sim. As fantastic as today’s flight simulation applications are (and they are indeed fantastic!), the flight sim experience is limited by the device(s) employed by the user. The application creators employ a virtual warehouse of special tools to build the application, but the user experiences the result on what is basically a general-purpose computer. Maximizing the flight simulation experience calls for a specialized device on the user’s end. It’s called a home flight simulator.  [Status: rough partial draft]

Joy Sticks

The first chapter addresses that quintessential flight control, the joystick. It begins by listing and defining the general characteristics to consider when simulating a joystick. It then describes the in flight control feel of four representative real joysticks: a basic non-assisted joystick, rotary wing joysticks, commercial service sidestick controller, and military service sidestick controller. The chapter concludes with a detailed project about making a floor mounted stick using readily available materials from a home building supply store, and perhaps Ebay. 

[Status (7 June 2008):  I've decided to revise the chapter project to use Hall Effect sensors rather than potentiometers. This takes a chapter that was virtually finished and knocks it back a few weeks.]

Control Yokes

No coverage of flight controls for simulators would be complete without addressing control yokes. A big issue for do-it-yourself hobby flight simmers is that control yokes are more complex. The mechanical linkages for even a single yoke are somewhat mysterious, and a linked dual yoke setup seems impossible. All that and more will be covered in this chapter.

The chapter project is a general aviation style control yoke constructed mostly from materials available through home building supply sources. The bearings that support the control tube are standard mounted ball bearings from an on line industrial parts supplier. The potentiometers that do the control position sensing are from an electronics parts house.

  [Status (7 June 2008): Currently a rough draft with a few major holes. The majority of the illustrations are done though all will need tweaking.]

Pedals

Pedals are somewhat in short supply in the sim world, yet are key elements in flying. The flight sim applications fudge it if there isn’t a set on the computer, but their lack is a significant distraction. If you’re looking for a better flight sim experience, there is no substitute for a proper set of pedals. That said, just what is a proper set of pedals? Should they move in a linear motion? How far should they move? Does the shape matter? And what are toe brakes, anyway?  Here is the first prototype for the anti-torque pedal project.

[Status (8 April 2008): Very solid draft. I will undoubtedly make a few more tweaks on it, but this chapter is ready to fly.]

Engine Controls

The primary engine controls are good things to add to your simulator. Having to use the keyboard to adjust power settings is a real distraction from the simulator illusion. As in other chapters there are descriptions of engine controls in real aircraft. The reader is given names of companies that offer engine controls suitable for simulator use. Projects include a twist grip collective throttle, and a basic throttle quadrant for a light twin.  [Status (8 April 2008): partial draft]

Position Sensors

Position sensors are devices that translate the physical movement of flight and engine controls into something useable by the simulation computer. Potentiometers are moderately reliable, cost effective position sensors, and the chapter starts by looking into them in detail. There are other positions sensors, however, that may be better choices in some applications. For example, a rotary Hall effect sensor can be used in applications that would wear out a potentiometer’s sliding electrical contact. The linear variable differential transformer, or LVDT, is useful in application having physical movement that is too small to effectively use a potentiometer. Finally, the synchro control transformer is a rotary position sensor used in many aerospace applications. If you want to use surplus military or commercial avionics this will give you some useful background info.   

Pictured below is part of the chapter LVDT project.  This is the signal conditioner that generates the signal that excites the LVDT, and detects and amplifies the returned signal. The design calls for low cost, commonly available parts. I think the most expensive parts are the two trim pots, at maybe a dollar and a half each. The chips are about $0.60. Resistors, at least if you buy in quantity, are a few cents each. The board design is single sided making it easier for those who like to make their own boards.

[Status (8 April 2008): Very solid draft, projects prototyped and tested. There are a few minor things I'd like to change. It could go to press as it is. We'll see.]

Computer Drawn Instruments

Adding an instrument panel to a home simulator that is separate from the scenery display device vastly improves the flight illusion. Doing so can be an expensive challenge for someone starting in the hobby. This chapter describes a relatively easy and low cost approach based on using computer rendered instruments on a separate monitor. You can use the stock panels in MSFS, or you can roll your own. Either approach will add to the flight illusion and boost the feeling of immersion.  [Status (8 April 2008): A reasonable draft. Project needs some work.]

Using Real Instruments

Using salvaged instruments that have actually been installed in an operating aircraft adds a feeling of realism that is hard to beat. Some instruments can be used in a simulator setting, and some, sadly, can only act as a source of parts. This chapter overviews the major classes of instruments and explains what can be used and how. It includes a project for interfacing some the synchro-based real instruments. 

The drawing below is one of many that illustrate the inner workings of typical aircraft instruments. 

And this picture shows the prototypes of the digital to synchro and 400Hz static power inverter projects in the chapter.

And here's a picture of an updated digital to synchro converter. The updates reduced the parts cost, improved the performance, and tidied up the board artwork a bit.

 [Status (8 April 2008): I revised the chapter to reflect the improved DTS project. There's a drawing that I think I'll add to. All-in-all, however, it's in pretty good shape. ]

DIY Instruments

Instruments add a pleasing visual impact of functional complexity to the simulator, particularly so if they are steam gauge style indicators that swing real pointers and have internal lighting. This chapter overviews air-core movements, RC servos and stepping motors as workable approaches to simulating flight and engine instrumentation. There are two projects, a basic stepping motor based gauge, and a  LED based, dual side-by-side set of engine gauges.   

[Status: (8 April 2008): At one point I considered this chapter to be done. Then I started added flow charts in other chapters and saw how helpful they are. So, I've down graded this to "strong draft" status, and plan to revise the sections that describe the project firmware to include flow charts.]

Scenery Display Systems

This chapter covers the basics of how we create a mental three dimensional world from the two dimensional images a simulator application generates. It goes into what we should consider when displaying these 2D images to get the best effects. There is an overview of the approaches taken by commercial simulator display systems and some recommendations for setting up a display system at home. The project will likely be a compact panoramic system built of multiple monitors and using Fresnel lenses to blend the individual images.  [Status (8 April 2008): strong draft, but no project as yet]

Panels

A proper array of panels is an important element in creating and supporting the flight illusion. If you are simulating a WWII bird you may be looking at a relatively small expanse of sheet metal sporting a crinkled black finish. If you’ve chosen a modern airliner for your project you’ll have significantly more panel area, and a fair portion will be magically backlit. This chapter will take you through some of the details of how flight rated panels are constructed and suggests a variety of alternative approaches to building or simulating them. It will touch on materials, colors, fonts and lighting. 

 [Status (8 April 2008): Strong draft, missing a few illustrations and a project.]

Hardware I/O Options

Ultimately you need a connection between the computer running the simulation application and the various elements that make up the simulator flight deck or cockpit. There are a number of options. This chapter will cover them in some detail. Included are an RS-232C to RS-422 adapter and an arbiter that allows multiple devices to peacefully share a single com port.  [Status: (8 April 2008) Strong draft,  first project is complete and tested, second project is designed, firmware written, but not prototyped. A few of the sections should be expanded. Considering third project.]

Switch Inputs

Switches are a necessity! Having to bang on a keyboard to start an engine or retract the gear definitely fractures the flight illusion. This chapter covers some of the special switches found in aircraft and suggests a few, rather more affordable alternatives. It then get down to the business of interfacing switches to the simulation computer. After all, it's nice to have a landing gear lever that looking like a landing gear lever, but it's even better if something happens when it's moved. 

The first project is a 16 switch input module, shown below.  It communicates to the host PC through an RS422 party line connection. Using the RS232C to RS422 converter, and optionally the arbiter, from the previous chapter, you can plug a bunch of these modules onto a single com port.

The second project will be a radio head using a rotary encoder and an LCD character display. It will also talk to the host through an RS422 connection. The prototype is partially assembled and working.

[Status: (8 April 2008) Solid draft, both project have been prototyped and tested. I've got a few red marks where I plan on tightening the writing, and one section that could be a bit more detailed. ]

Warning and Status Lights

Indicator lights play varied roles in a simulator. The most important indicator lamps in a fixed gear G/A plane may be the marker beacon lights. A fighter likely has a master warning indicator that serves to get the pilot to look at the annunciator panel, a compact collection of many system indicator lamps. This chapter provides a background on lamps, both incandescent and LED. Projects include a dimmer, and Bell Jet Ranger and F-16 style warning panel.   

[Status (8 April 2008):  Strong draft but need to add a flow chart. I revised the electronics, so need to prototype again.]

Interfacing with MSFS

The simulator flight deck is a silent museum diorama until it’s brought alive by a simulation application. That requires a high quality connection between the application and the various systems that make up your flight deck. The subject of this chapter is how to interface with Microsoft Flight Simulator.   

MS FSX Deluxe ships with SimConnect, the official API for talking with the flight sim engine. Not surprisingly, the main focus of this chapter is on SimConnect; how to set it up, how to use MS VC++ Express to code against it, how to get data out of FSX and how to push data into it. The chapter will also give brief coverage to other I/O avenues.

[Status (8 April 2008): Strong draft that could be improved with a few illustrations. This is a software chapter and the writing gets a little dense.]

Audio Systems

Part of the flight experience is what you hear. The simulation developers have gone to a great deal of trouble to capture real flight sounds. There are also Internet based com systems such as Squawk Box and Team Speak that support ATC and team flying. This chapter describes your audio options. The project is an audio panel that allows various sound sources to be mixed, provides a local intercom function, and accepts flight rated mic/headset connections.  [Status (8 April 2008): rough outline]

Force/Motion Cueing

Force/motion cueing encompasses all methods of applying a force directly to the participants in a simulation in order to boost realism or add training clues to the simulation. Motion systems are likely the best known force cueing systems. However, control-loading, G-seats, anti-G suits and even vision systems fall in this category. This chapter describes each and presents their relative merits. The project is a tactile transducer (bass shaker) amplifier. [Status (8 April 2008): rough partial draft, project designed, documented, but not prototyped.]

     Since 25 November, 2005

It's possible that I'm not as smart as I think I am. (Occasionally, I have moments when I know this to be true. Fortunately the feeling passes quickly.) Although I have tried to make this information as accurate as I can, it is not only possible, but also quite likely, that errors lurk within. I cannot and do not warrant these pages to be error free and correct. Further I accept no liability for the use of this information (or misinformation). If, after reading this, you are still interested, please be aware that the contents of this site are protected by copyright (copyright © 2002, 2003, 2004, 2005, 2006, 2007, 2008 by John M. Powell). Nonetheless, you may copy this material subject to these three conditions: (1) the copyright notice is copied and presented along with the material, (2) the copy is used for non-commercial purposes, and (3) the source of the material is properly credited. And of course, you may link to this page.