Note:
I wrote and tested this program in the summer of 2000. It was a lot of fun but I realized that having a laptop in the cockpit of a Cessna 172 is not very ergonomic. The program worked fine and for some reason was especially impressive taxing on the ground because you could see the taxiways and runways as you passed them. At some airports the buildings were exactly the same. I plan to add more to this program in the future.
That trip in the summer of 2000 was also notable because we had an inadvertent landing. Read about the taking a Cessna 172 out of a hayfield here.
General Overview
GPStoFS provides an interface between a GPS receiver and Flight Simulator 2000 from Microsoft. You connect your GPS to your computer (usually a laptop) through a serial cable. GPStoFS takes the position, speed and altitude data from your GPS receiver and 'forces' Flight Simulator 2000 to fly with the same parameters.
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A Quick Point:
If you plan to use GPStoFS along with your GPS receiver as a sole source navigational / flight instrumentation system with the following goals:
then I have a few suggestions.
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Passing over O'Hare. This time a top-down outside view is selected on the lower left and the FSNavigator free add-on moving map display is in the FS2000 window. |
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Approaching O'Hare. The wind is 7kts from 29 degrees. The bottom left GPStoFS window displays a wind compass showing wind relative to the airplane. Here, there is a 7 knot crosswind component since the airplane heading is 302 degrees. The bottom right FS window is the default FS2000 GPS. |
Why?
That's a little hard to answer. There are several reasons why I thought driving FS2000 from inside a real airplane would be a neat idea. Two are obvious: position and mapping. As pilots, we have an inherent desire to know our positions at all times and we like to have it conveyed in the form of a map with landmarks, navaids, etc. FS2000 by itself or enhanced with 3rd party add-ons does an excellent job of providing a moving map display. There are lots of packages available commercially that provide moving map / flight planning and accept input from GPS receivers (like RMS Vista, FlightSoft or Jeppeson FlightStar, etc.). These are all fairly expensive ‘canned’ programs that don’t really add much more useful information than FS2000 and often a lot less.
FS2000 also provides terrain mapping. Built into FS2000 is a 1 km spacing terrain model which when used 'real time' provides decent terrain mapping capability so AGL (Above Ground Level) and Ground Level (GL) altitudes are always available. There are some 3rd party add-ons which can bring that to 152meter resolution based on USGS information.
Mapping and terrain avoidance are just two of the capabilities. In addition I have created GPStoFS as a stepping stone and a bit of an experiment to see how an off-the-shelf flight simulator can be coaxed into a usable flight instrumentation system in a real plane. The difference from a moving map display is that FS2000 with GPStoFS creates a 'virtual' plane flying congruent to the real one. Later I would like to add some resolution enhancements to GPStoFS from external sensors such as piezo gyros, magnetometers, etc. so that FS2000 attitude, heading, airspeed, etc are 'real'. Right now, the course and altitude information from the GPS receiver is fed to the autopilot of FS2000 and FS2000 mimics the course but with a little delay. My GPS (Lowrance Airmap300) sends out data every two seconds or so. This is fine for general position mapping, but is a little slow if a turn is initiated. I hope later that I can augment the real time display of FS2000 with a couple of cheap off-the-shelf instruments.
What Else?
Besides controlling the flight of FS2000, GPStoFS does it's own calculations of TAS (true airspeed), and Winds similar to an E6B type computer. These calculations need the current altimeter setting and outside air temperature. Initially, GPStoFS assumes there is no wind and the TAS (true airspeed) and MH (magnetic heading) readings are the same as the GPS GS (groundspeed) and MC (magnetic course). While in flight you might notice that there is a difference between the IAS (indicated airspeed) and MH (magnetic heading) of the plane and the IAS and MH readout of GPStoFS. If there is a difference and you are in straight and level flight, you can manually enter the IAS and MH from your DG (or compass) and the airspeed indicator and then click 'Calibrate'. That difference is immediately resolved into a wind calculation. This wind calculation is also sent to FS2000 so the virtual plane is flying with the same winds as the real one. After that the IAS and MH readouts from GPStoFS should be the same as the real aircraft even after making turns, etc. Any major difference would be an indication that the winds aloft have changed. There is also a window from GPStoFS that shows a wind compass and graphically portrays the wind acting on the plane with crosswind and headwind component readouts. A nice feature on final in a really bad cross wind, or...do you really want to know?
What do you need?
From a hardware standpoint you need a reasonably fast computer (266mhz or better). FS2000 is a cpu hog. In order to get any performance at all out of FS2000 it really wants a fast machine with a macho 3d graphics card. Since it is pretty obvious that you will be using a laptop as a computer platform you will need a relatively new one. A dusty old 486 laptop from a few years back won't cut the mustard. Unfortunately, most laptops are not very fast yet (comparably) and do not feature really quick graphics cards.. Luckily though, most of us private pilots are not maneuvering at high speed and at low altitude in the middle of downtown Chicago, so a really fast and smooth graphics display is not absolutely necessary.
I have an IBM Thinkpad with a 266mhz processor. It is running Windows2000. I noticed that I needed to use the Task Manager to set the CPU priority to High for gpstofs.exe. When FS2000 is running it steels almost all available cpu cycles from everything. Microsoft didn't think you would want to be doing other things on your machine while flying their simulator. Anyway, I noticed that I lost some of the GPS squawks if I didn't set the priority up a bit. I must admit I haven't tested it yet on Windows98.
I have rapped everything except one module into a single downloadable file. There is one module called fsuipc.dll written by Peter Dowson which is the main IPC (interprocess communication) facilitator. It needs to go into the Module folder under the main FS2000 folder and can be downloaded here. If you have any FS 3rd party add-ons you might already have it, but there have been a flurry of updates to it recently so you might make sure you have the latest version.
The GPStoFS program is installed normally by running 'setup'.
There is one other file in the package which contains a FS aircraft specifically tailored to GPStoFS. GPStoFS will work fine with any FS plane that has an autopilot that allows heading, altitude, and IAS hold operations. Most FS light plane autopilots don't have auto throttles and the ability to hold an airspeed. I have made this plane (GPS-Airplane) to mimic a light plane with a really low stall speed and a super autopilot. If you use a 747-400 instead of a light plane to cruise around at 100kts you will find yourself stalled! It is best to pick a plane (or use mine) that can handle the flight regime you intend and with the proper autopilot capabilities.
The zip file gpsairplane.zip (in the main zip file) contains the plane. You should extract it to your FS2000\Airplane folder honoring the folder names below.