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Information regarding GPS

One of the key features of the Tangent Flight Computer is it's ability to use information from a GPS (Global Positioning Satellite) to provide key information for cross country flight. Arai Design is a dealer of Garmin handheld GPS units and we also sell several accesories for using GPS with the Tangent.

You will find the following on this page:

• Arai Design GPS Accesories

• How to Choose a GPS for Flying
  • GPS' for in the air.
  • GPS' for retrieval.
  • Using Nicad Rechargeable Batteries in GPS Handhelds
  • GPS Table of Features
  • Read Garmin's statement on Waterproof Standards

Arai Design GPS Accesories

GPS Bracket for Hang Gliding

Velcro bracket with sturdy aluminum plate. Allows access to data port. View a picture

Garmin to Tangent data cable

Available in custom lengths.

As a Garmin dealer, we often get asked our opinion on the difference between the various Garmin handheld GPS models and thier suitability to our gliders and our vehicles. Since I last updated this article the GPS models available have changed dramatically. As we have become acustomed to in electronics, features have grown, power consumption has diminished and prices have dropped.

In the past tradeoffs had to be made for durability and receiver performance. That is no longer the issue, as all of the Garmin handhelds are using very efficient 12 channel receivers. While some models might perform better in a car, all models will work superbly in the air. The choices come down to features vs cost.

This article covers the following:

• In flight use.
• Retrieval vehical use.
• Using Nicads in GPS Handhelds
• Table of features.
• Garmin's statement on "Water Proofness"

For use in a hang glider or paraglider:

For flying only (or infrequent use in the car,) the economical choice is the Garmin GPS 12. It is the lowest cost, most durable and it works great. It comes with an internal antenna, which is much prefered over the external (I cynically call them break-away) antennas of the 48 and III+ . The GPS 12 has no ability to connect to an external antenna, so it is not the best choice for use in a car, but experience shows that it works quite well on the dash of most vehicles.

The deluxe choices now are the handhelds (GPS Map, GPS III+, eMap) with downloadable maps that display right on the unit. While these maps are a little difficult to read in detail in the air, you can at least tell your crew what town you are near, which is much easier than coordinates for chasing while you are in no danger of landing. Of course difficult retrieves will always require coordinates.

These units allow for downloading of custom sections of map and provide a lot of detail. They even have the ability to display topographic information, although I don't recommend trying to read it in the air, at least not in my gaggle!

There are currently three map units available that I would consider for flying use: The GPS 12 Map GPS III+ and the eMap. The GPS 12 Map is the best choice. I don't recommend the GPS III+ - which was the first map capable unit available and became quite popular - because of it's external antenna and it's odd form factor (shape.) The eMap has potential, but I haven't tried it yet. At this time I can only provide some basic information as I have not had a chance to fully evaluate them. I will be doing that in the near future.

eMap The eMap is the low cost unit, and while it has some interesting features - a bigger display, more memory and lower cost than either the GPS 12 Map or the III+ - it has some serious drawbacks. It only uses 2 instead of 4 AA batteries, giving it a manufacturer's stated battery life of only 14 hours (on 2 cells) as opposed to 36 hours (on 4 cells) for the 12 Map or the III+. The other drawback is a less water proof case, which probably also means less durable. The other drawback is limited route capability. See the GPS Feature Table for specifics. Also see Read Garmin's statement on Waterproof Standards

GPS 12 Map The 12 Map comes in the proven durable and reliable package that the GPS 12 comes in. It has all of the features of the III+: down loadable maps, 4 level gray display and 36 hour battery life it is lower in cost and doesn't have the fragile external antenna. It also doesn't allow for rotating the display like the III+ does, but for flying that is not an issue.

A GPS for your Retrieval Vehical:

• The GPS 12
• eMap
• GPS 12 Map
• GPS III+

GPS 12 The GPS 12 is the economical choice. It has all the performance needed to function well as a retrieval unit, plus it's a good backup for flying. It lacks the map, but in serious retrieve situations it's coordinates you need. The maps just make it easier. If you load up your car with a canopy of gliders, then the GPS 12's lack of external antenna capability will have you hanging your arm out the window. If you have a driver that has been good to you, then you should consider one of these as a gift. Especially if that driver has been on a late night retrieve without a GPS.

eMap The eMap is Garmin's low cost entry to GPS mapping. It's strong points are the capabilities of it's map data base. The eMap even allows you to enter an address to come up with a waypoint! Useful if a pilot's GPS batteries die and he walks out to a farm house to call his driver on the phone. The eMap will accept an external antenna. This may be the best choice for a retrieve vehicle in terms of cost/performance.

GPS 12 Map This unit can't hold as much data as the eMap, but it can hold all the detail you need for a likely retrieve on a hang glider or paraglider flight. It is more durable than the eMap, but it will cost more. The 12 Map will accept an external antenna.

GPS III+ This unit's claim to fame is it's rotatable display. All of the above units need to be held upright to be read in a natural position. The III+ can rotate it's display into "landscape" mode, which will allow you to set it on its side on the dashboard and easily read it. It has the exact same mapping capability as the 12 Map and it too accepts an external antenna.

USING NICAD BATTERIES IN THE GARMIN HAND HELDS.
My personal philosophy is to forget Alkalines. They are wasteful and expensive in the long run. Nicad batteries are the way to go. You can buy high capacity Nicads for about $15 for a set of 4 and they will last the life of your GPS. Make sure you get batteries that are at least 800mAhr capacity. Nicads can be found that have capacity of up to 1000mAhr that give you a few more operation.

A newer battery technology known as Nickel Metal Hydride (NiMh) is available with capacities of up to 1300 mAhr. They are not my preference as they are more expensive, don't perform as well at low temperatures and have very quick self-discharge (they run down even when not in use.) In addition they require special chargers because they don't tolerate overcharging as well as Nicads. The are probably better suited to pilots flying in warmer climates. If you want to use NiMh batteries, I recommend that you get a charger with zero slope (prefered) or peak voltage detection as a method of charge termination, as well as a low trickle charge rate. Without these precautions you are likely to see greatly reduced service life from NiMh batteries. Aside from saving the batteries, this sort of charger will allow 1 hour charges. You will find the best source for this sort of charger is the radio control hobby catalog. Electric R/C cars in particular use these chargers.