Sunday, April 26, 2009

The $100 Glide Computer

From Land, Sea and Sky

LX, ILEC, Cambridge Instruments, Borgelt, all manufacturers of excellent panel mount glide computers. Interface to a PDA and you've got moving map, speed to fly and navigation all at your finger tips. The only real drawback to these instruments is the price. $1000 to $6000 depending on used/new and what options loggers and integrations are required. I've been keeping my eye on the used market for something to drop into my ASW-20 which currently has a very old Zander 820 flight computer. It provides speed to fly, but no navigation capability in a modern sense.

While on vacation in New Zealand I picked up a copy of their soaring magazine and stumbled across a short article about an open source project called XCSoar that provided glide computer capabilities on a PDA and even more interesting, on a PNA (Personal Navigation Device). Many of us already own a Garmin Nuvi or StreetPilot of some sort that would qualify as a PNA. XCSoar won't run on a Garmin, but it will run on a number of other PNAs out there.

Upon returning from New Zealand I began my quest to see if I could get one of the PNA glide computers up and running. Some research on the XCSoar site uncovered a variety of brands that would likely work. Most in the $300+ price range. Not bad compared to thousands, but also not something you can just toss around in the hopes of it being useful.

More late nights and lots of product literature reading and I uncovered a potential PNA that would fit my threshold for cheap but functional. The V7 Nav740 was available for under $100 off of Amazon and it ran a version of Windows CE which seemed to be the only criteria for running XC Soar. That and being able to unlock it.

UPDATE: Amazon is apparently out of stock and the only V7 Nav740 is now listed at $309 from another seller instead of the $89 I paid. Look into the MIO C320 as another cheap alternative.

My Nav740 arrived after a few days and I began the search to figure out how to unlock it. Unfortunately, since I had bought a model that didn't have any setup instructions off the site, I was on my own. Unlocking it turned out to be relatively easy. A simple text file on the SD card controls what you see when you turn on the GPS. Getting XCSoar to run correctly took a few more late nights of following Red Herrings on various forums and cobbling together the right set of files and configurations.

In the end, I have a fully functional glide computer with GPS navigation, integrated task calculations, speeds to fly, final glide computer and a plethora of other features I won't bother talking about. is a great place to start looking for that information. Oh, and the Car Navigation functionality still works just fine, so you can take it out of the glider and put it in the car and find your way to wherever it is that you're going.

This really is a work in progress, I'm learning as I go and will try to update this blog entry or better yet, feed this back into the project.

The basic steps for setting up your own V7 are as follows:

  • "Unlock" your GPS to enable installing and running other apps.

  • Install the PNA version of XCSoar executables on the SD Card.

  • Install the sample data

  • Fire it up and start playing around

Unlock and prep your GPS for file installation

Edit the AddOns.txt file in the root directory of the SD Card.
Make it look like the following:

V7 Navigation = "icons/V7.bmp", "\\Storage Card\\iGO\\iGOpna.exe"
Explorer = "icons/files.bmp", "\\Windows\\explorer.exe"
XCSoar = "icons/files.bmp", "\\Storage Card\\XCSoar-PNA.exe"
XCSoar Simulator = "icons/files.bmp", "\\Storage Card\\XCSoarSimulator-PNA.exe"

Navigation = "\\Storage Card\\iGO\\iGOpna.exe"

Download the PNA Version of XCSoar software from the downloads location for XCSoar off of Sourceforge.

You'll probably need to unzip the file somewhere on your hard drive.

  • Copy the XCSoar-PNA.exe file in the root directory of the SD Card.

  • Copy the XCSoar-Simulator.exe in to root directory of the SD Card.

  • Copy the GRecordDll.dll to the root directory of the SD Card.

Download my XCSoarData directory example for the central California area.

Unzip and copy the XCSoarData directory to the root directory of the SD Card.

The zip file of the XCSoarData directory that I'm providing is set up for Avenal, CA and the surrounding area. It'll probably work well if you fly out of Hollister, but elsewhere will require additional waypoints and maps generated. I'm currently working on an updated waypoint file that incorporates more of the Hollister waypoints.

What I've included to get you started:

  • Glider polars for:

    • ASW-20

    • Schweitzer 1-26E

    • Blanik L-13

  • Terrain and Airspace for Central California

  • Waypoints for the greater Avenal area.

  • A couple of IGC files from my early flights with the device, to give you something to play back in Simulation mode.

Getting Started:

This isn't intended to be a replacement for the documentation off of the site. It will hopefully kickstart you down this particular installation though.

With the software and data directory installed you should be able to restart your V7. This time when it restarts it will come up with a Launcher menu. You should have entries for XCSoar and the XCSoar simulator as well as the V7 Navigation.

From Land, Sea and Sky

Tapping on your preferred application will cause it to launch. For now, that's as far as I'm going. More reading and instructions are available on the XCSoar Site.

More Info:

The V7 has nothing short of terrible battery life. On top of that, if the battery fails while you are mid flight, it will not save your IGC file. This is lame, but is what it is and it's better to just be prepared for it.
To combat this terrible battery I've tried a couple of routes. First was to buy a small battery pack that held 4AA batteries and provided a USB output. This seems to give about 3 hours of runtime. Not much, but better than an hour or so.
Not being satisfied with a 3 hour limit, I opted for a more robust solution. offers a 38watt/hr 12v battery in a case with a cigarette socket and a charger for about $50 shipped. Over half the cost of the GPS, but the GPS is nothing without power and a long lasting solution was a requirement for me when not in my ASW-20 with it's 12 Volt battery. The battery with pack and outlet was a perfect match. The pack has straps so i can tie it into our club aircraft safely. The socket offers a simple solution that works with the cord that came with the GPS and the charge automatically goes into a trickle mode, so I am not stuck monitoring the charge rate and unplugging it after the precise amount of time.

Hopefully this little tutorial helps.


Joel said...

Very cool Morgan! Thanks for the quick-start set up. I've got a PNA on order and hope to try it out next week.

Andrew said...

I followed your instructions and it worked flawlessly! Thanks so much.

Calgary, AB, Canada