Although the rebound height of a ball is affected by its incident angle, a vertical drop can provide an indication as to the suitability of a surface for tennis.
To minimise the effects of environmental conditions and ball properties, the test surface is measured relative to the rebound height on a reference surface.
Test apparatus consists of:
- Standard ball.
- Reference surface, which shall be smooth, rigid and horizontal, e.g. polished granite.
- A means to measure rebound height, calibrated to ± 1%, such as a measuring staff and video camera.
Check the height-measuring accuracy of the apparatus against a known standard prior to testing.
1. Drop the ball from a known height (at least 127 ± 1 cm) onto the reference surface five times and measure the rebound height (BHT) on each occasion, ensuring that there is no parallax error in the measurement.
2. Repeat step (1) on the test surface.
Note: The ball should be dropped in a manner that does not impart any impulse or spin.
Calculation of results
The test value is the mean RPR for all impacts. For on-site tests, the variation is given by the maximum difference in the mean RPR for each location.
The preferred value for Relative Percentage Rebound is ≥ 80. The maximum variation in RPR between the test location means should be ≤10.