GPS Rally Computer
GPS Rally Computer is a Universal app designed to simplify computations necessary to navigate a traditional
time-speed-distance (TSD) automobile rally. The design and implementation is based on specifications
outlined by Clarence Westburg and Rich Bireta, commonly know as the Simple Rally Computer or by its
acronym SRC. The design mimics in digital form the functionality of the classic Zeron 660 and 880 rally computers.
A TSD rally is comprised of stages set along a route defined by written instructions. The first stage is the
Odometer Check stage that allows you to calibrate your car’s odometer with that of the Rally Master’s odometer.
In later stages you will follow a course at a particular average speed that will change from time to time
at places that are generally unknown in advance.
In order to drive the course at the prescribed speeds. Odometer measurement is obtained from Apple’s GPS receiver
or third-party devices via Bluetooth.
The GPS Rally Computer allows you to do all this and much, much more. For more documentation, download the
Features of the GPS Rally Computer:
- Clock time in either minutes and seconds to tenths of a second or decimal minutes to thousandths of a minute
- The clock is a 24-hour clock to simplify computations
- Distance measurements in either miles or kilometers to either two- or three-digit precision
- The car's odometer distance measurement may be the same or different than the official rally odometer distance measurement
- One button click to reset default conditions for starting a rally
- The internal computer clock can be adjusted to match the official rally clock
- The distance between the GPS receiver and the position on the car where the rally measurements are taken (the front wheels,
for example) can be added for improved distance precision
- A "sprocket" button in the top menu bar allows access to the app settings from within the running application including settings for display
of certain items
- Calibrate the car's odometer to the official rally odometer on the odometer check stage via a popup
- Change average speed (CAST) on a custom popup keypad or button input
- Preselect the next CAST to simplify the process of changing speed on each stage and setting CAST to zero for transit zones
- As time passes and as the car's odometer is incremented, the actual speed over the course is compared with the
expected speed. The difference in seconds or hundredths of a minute is displayed along with an indication of either "Early" or "Late"
to stay on pace
- Time errors may be displayed in either of two modes selectable in the app Settings
- Pause or Gain time or take a Time Allowance on any stage or within a transit zone
- Option to Pause or Gain at user-defined preset seconds or cents
- Handle off-course corrections to time and distance with Reverse button
- Record "splits" of time and error at any time with a Split button
- Record "control" and reset time error and distance to zero and increment next starting time 5 minutes later
(distance and time are modifiable) with a Control button
- Log table that records time, elapsed time, speed, distance, and error for various actions such as splits and CAST changes
- Set next starting time for the Next CAST and have the time tick down on the master clock and autostart CAST, or override with a manual button click
- Optionally, use a Dual GPS receiver via Bluetooth to supplement or substitute for the Apple internal GPS
Note: Use of the GPS Rally Computer during any particular rally will be subject to the rules and instructions
governing the rally and will likely define your category or class among participants. Some rallies may, in fact,
prohibit use of this app. Also, some rallies may have classes strictly for those with Simple Rally Computer (SRC) apps.
For better GPS reception and improved accuracy while rallying, third-party wireless GPS receivers are recommended.
This app has been tested with Bluetooth connectivity to a Dual XGPS150A Universal GPS Receiver.
Disclaimer: Continued use of GPS running in the background can dramatically decrease battery life.