Thus, knowing the burn rate of a propellant and how it changes under various conditions is of fundamental importance in the successful design of a solid rocket motor.
[2] One device for measuring the burning rate is a V-shaped metal channel about 1–2 feet long wherein a sample is placed, with a cross-sectional dimension of approximately 6 mm or 1/4 in.
Burn rate (typically expressed in mm/s or in/s) is the sample length over time at a given pressure and temperature.
For solid fuel propellant, the most common method of measuring burn rate is the Crawford Type Strand Burning Rate Bomb System[3] (also known as the Crawford Burner or Strand Burner), as described in MIL-STD-286C.
However, there is a difference in opinion in differentiating the three in the absence of firm numbers at a given pressure or temperature.