TSD Rally Computer is an iPad app designed to simplify computations necessary to navigate a traditional time-speed-distance (TSD) automobile rally.

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 Rallymaster’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. Each change in average speed marks the beginning of a new leg of the race within a stage.

In order to drive the course at the prescribed speeds, you must keep track of your odometer reading along the way.

The TSD Rally Computer allows you to do all this and much, much more. For more documentation, download the User’s Guide

Features of the TSD Rally Computer:
- Clock time in either minutes and seconds or decimal minutes
- The clock itself may be a 24-hour clock or a 12-hour clock with AM and PM
- Distance measurements in either miles or kilometers
- 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 iPad clock can be adjusted to match the official rally clock
- The car's odometer reads up to 9999.99 miles or kilometers and can be incremented by simple button clicks
- Calibrate the car's odometer to the official rally odometer on the odometer check stage via a popup
- Change average speed (CAST) with a single button click
- Preselect the next CAST to simplify the process of changing speed on each leg
- The CAST button can be deactivated to prevent accidental touching
- Preset CAST speeds and times to travel one mile or kilometer at those speeds with via a popup
- Use scroll wheels to quickly and easily change time, speed, or distance throughout the app
- 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 is displayed along with an indication to either "Speed Up" or "Slow Down" to stay on pace
- Pause or gain time on any leg with a toggle button and at times chosen with scroll wheels
- Handle off-course corrections to time and distance with a toggle button
- End stages at checkpoints with a single button that has protection from accidental touching
- Set departure time from a checkpoint and have the time tick down on the master clock
- Use a handy popup to perform ad hoc computations of time, speed, and distance given any other two variables
- Hide the bottom toolbar to avoid accidental selection of popups

Note: Use of the TSD Rally Computer during any particular rally will be subject to the rules and instructions governing the rally and may also define your category or class among race participants. Some rallies may, in fact, prohibit use of this app.