Research is a good start.
Read this site. Read Building a Flight Simulator Cockpit by Herman Lenferink. Read Simprojects.nl by Roland van Roy. Visit the sites of flight deck builders. Browse through the entries at the Hybrid FlightSim Builder's Registry. Drop in on the home cockpit builder forums at Avsim.com, MyCockpit.org, FlightSimNetwork.com, SimHQ, Simviation and simFlightNetwork.com. There is an excellent builder's discussion over at Flight Deck Solutions. If you are specifically interested in fighter sims, you should also check out the forums at ViperPit.org and DCS. Hovercontrol has a forum thread specifically for helicopter 'pit builders. Read the current posts and at least skim their archives.
This hobby has a great many options. The more knowledgeable you are, the better choices you will make.
Give serious thought to the simulator software.
An early choice should be what simulation software you will use. Most hobbyists want functionality in their cockpits. Controlling the simulator through custom yokes, pedals and even rotary switches is possible with virtually every game simulator. Making simulated instruments and indicator lights work requires the ability to extract data from the software. This limits the choice of simulation software.
Microsoft Flight Simulator
Many hobbyists base their projects on Microsoft Flightsim, not simply because it is a well built, supported product, but also because third party software provides a bi-directional interface with it. The most frequently used software is called FSUIPC and is covered in the Interfacing section. As MSFS has evolved FSUIPC has been updated to work with the new releases.
FSUIPC also works with Microsoft Combat Flightsim2. Unfortunately, it does not work with CF3.
Now that MSFSX is out, we have access to SimConnect. This is a utility provided by Microsoft for interfacing with FSX. SimConnect ships with the deluxe version of FSX. It doesn't automatically install with FSX installation. You'll have to do a separate install from the DVD. The DVD also includes documentation on how to use SimConnect. In addition to reading the docs, also take a look at FSDeveloper and the SimConnect forum over at AVSIM. If you're a Delphi fan, visit Scott Hendry's site for Delphi headers and sample Delphi programs that talk to SimConnect.
Lockheed Martin Prepar3D
Prepar3D is based on Microsoft ESP, the commercial simulation platform developed from MSFSX.
DCS: A-10C Warthog
If you're interested in ground combat support flight sim, Eagle Dynics DCSW is something to consider. This is a detailed sim with data export which you can configure through Lua scripts. There is an active user community you can join through the support forum.
DCS: Ka-50 Black Shark
DCSBS is another excellent, detailed flight sim from Eagle Dynamics. It's based on the Russian Ka-50 attack helicopter.
Falcon 4 has a band of followers who have built cockpits around it. Although its maker, Microprose, is no more, there have been significant enhancements made by various F 4 community members. Adherents feel it is the best fighter simulator regardless of its age. A remnant debug feature is the basis for a limited bi-directional interface. Memreader, a freeware module, exploits this feature to provide user developed code an interface with Falcon 4. Memreader is also covered in the Interfacing section.
In particular, take a look at Benchmark Sims. BMS 4.32 is a major update for the F-16 sim community by community members.
IL:2 Sturmovik AEP
The 2.01 patch to the Ace Expansion Pack adds a UDP server that will export a variety of instrument readings. UDP is a network protocol that can be accessed through use of Winsock, a Windows networking API. The 2.01 patch includes the file "devicelink.txt" that documents this feature. (Thanks to Jari-Matti for alerting me to this.)
Mike Couvillion has an extensive C++ wrapper for device link. Check the forum on the Wing Walkers site for the code, sample applications and helpful comments.
You might take a look at SimHQ.com in the IL:2 Sturmovik FB forum. There was a thread in early August, 2004 about "UDPSpeed", a program that makes use of the UDP server. It may serve as an example.
X-Plane is one of the few commercially available consumer flight simulators that possess a designed in, general-purpose interface. The X-Plane web site provides the details in the "Hacking X-Plane" section.
Lock On: Modern Air Combat
The V1.02 update adds the capability to extract data from LO:MAC. Check the UbiSoft LO:MAC forum for more information. This makes use of a C-based scripting language called Lua. Details on Lua can be found at Lua.org.
It's also possible to import data into LOMAC. There is an interesting thread on the ED Forums titled "Experiment - Controlling Lockon using a PDA". [ED Forums > English > Community Area > Tech. Discussion 1/16/2008]
LFS Technologies is a small, Southern California company offering a range of Linux-based flight sim products and services to both the professional and hobby flight sim communities.
Flightgear Open-Source Project
The Flightgear open-source project is a non-commercial simulator that you might consider. The project makes source code and documentation available. With the inner code structure open to inspection, it should be possible to extract the necessary information to drive a homebuilt cockpit. (My thanks to George Patterson to alerting me to this option.)
Sailors of the Sky
If you are interested in glider simulations, Sailors of the Sky is a package you should look at. It's designed specifically as a soaring simulation. It has multi-player over Internet capability and exports data in NMEA format. This data stream can be used to drive a panel of simulated instruments. See the Polyt - S glider simulator site for an example of a sim using this software.
Give some serious thought to software in general
Developing basic coding skills gives you more flexibility as you develop your simulator. You can do a lot using out-of-the-box simulation applications. If you program, you can do a lot more. You can expand upon the simulation application functionality by adding more detail aircraft system simulations. You can develop new interface code.
The cost of programming is primarily your own time as you learn. Many software tools are freely available. For example, the express editions of Visual C++, Visual C#, and Visual Basic can be downloaded from Microsoft.
Another early discussion to have with yourself (quietly of course, people will wonder if you're too loud) concerns the interfacing hardware you will use. Here are a few of the more "flight sim friendly" choices.
EPIC is kind of the grand daddy of flight sim I/O systems. The current version is USB based. It works with an assortment of expander and I/O option cards. It comes with software; EPL the Epic Programming Language. The system is versatile, but takes an investment in time to learn.
Flightdeck Solutions InterfaceIT
Flightdeck Solutions produces several I/O products for use in simulators. More info at www.flightdecksolutions.com.
Flight Illusion GSA-10
Flight Illusion Simulator Systems got their start by making simulated instruments. Their product line has expanded and includes an I/O module. More info at www.flightillusion.com.
FSBUS is a totally free design that makes use of the PC's serial port. There are one or two people who have made circuit boards for sale roughly at cost, but the intent was that hobbyists would download the documentation and build their own systems. A progressively more capable software driver module is being developed that provides the capability of modeling complex aircraft systems. More info at www.fsbus.de.
IO Cards is a USB-based system offering a number of modules for switch and rotary encoder inputs, and light, RC servo and stepping motor outputs. The IO Cards suite is a product of the collaboration of several people making up the Open Cockpits Project. The design files are available as free downloads. Unpopulated circuit boards, as well as, built and tested cards are available at nominal cost. More info at www.opencockpits.com.
Beta Innovations was a small Canadian company that developed high quality USB-based modules for both input and output. The company is no longer in business, but you may find the products second hand.
PHCC - The PIC HomeCockpit Controller
PHCC is a micro controller based system designed around several models of the Microchip PIC line. Development is ongoing. This is a built-it-yourself project. Documentation is available from cockpit.varxec.de/electronics/PHCC.html.
To quote the Phidgets site, these are "physical widgets for prototyping physical user interfaces". USB-based, they come in several flavors. Some offer analog and digital in, others, analog and digital out. Some talk to RC servos, other listen to switches. Phidgets come with a driver module you can interface your software to. Phidgets the company has recently become interested in the flight sim community.
Velleman offers a variety of electronic goodies including the K8055 and VM110 interface boards. They have five digital inputs, eight digital outputs, two 8-bit analog inputs and two 8-bit analog outputs. Velleman products are carried by a number of vendors world wide.
A General Observation or Two
The feeling of immersion (or the "suspension of disbelief") you have while using a simulator is enhanced by a pair of synergetic factors . The first is the addition of features that you know are part of the real thing, like being able to control your B747 sim with a B747 yoke. The second is the absence of things that remind you that you are not in the real thing, like seeing the your living room wall behind the monitor running flightsim.
To get your best bang-for-buck, keep these two factors in balance as you pursue your project.
A second observation is that it is easy to imagine a home cockpit project that is very attractive, but will take a long time to complete. Well, the truth is that most home cockpits are never complete. The hobby has a very large element of discovery. The more you do, the more you learn, the higher you set your sights, and the more your projects grow. There is always something that calls out for improvement or expansion. It's part of what makes the hobby fun.
The downside is that you can find yourself with a sim that promises to work any time now, just not today. If you truly enjoy the building aspect of the hobby, that's fine. Many of us like the opportunity to sim as we build, though. So, if building isn't most of the fun for you, plan a sim construction sequence that evolves a working cockpit a step at a time.
And the next step is…?
Each project is a custom work-in-progress. The approach you take will depend upon available resources; skills, time, money, physical space, etc. There is no one-size-fits-all roadmap. Your project will be unique, and only you can plan it. Nonetheless, there is a general guideline you can use to add a bit of structure to your planning.
Divide your simulator project into a number of smaller projects. Prioritize them by the degree that you will interact with then when completed.
You'll probably come up with a list similar to this.
- Flight controls
- Engine controls
- Flight instruments
- Engine instruments
- Systems indicators
- Systems controls
Somewhere in the list you'll want to add the visual system used for the through the window views. If you're happy with a single monitor, the visual system may be rather low on the list. Or not!
You'll also want to consider the cockpit/flight-deck enclosure. To your taste, it may be a complete surround or virtually nonexistent. How important is it to you, and where should it be in the list?
You may want to break some of the projects into yet smaller projects to make them more manageable. For example you may decide to consider navigation instruments separately from the primary flight instruments.
How well does the construction sequence balance the remove-distractions / add-enhancements tradeoff? Does your construction sequence allow you to fly between additions to your sim? It should! Tweak the construction sequence so that each construction step adds the largest possible gain to your sim experience.
Remember, these are personal judgments, and you are building a customized simulator. So, get yourself a notebook and start sketching ideas.