In the world of model aircraft there are several competition classes to signify engine displacement.
| Class | Cubic Inches | Cubic Centimeters | |||
|---|---|---|---|---|---|
| align=center | 1/2A | align=center | 0.000 - 0.050 | align=center | 0.000 - 0.819 |
| align=center | A | align=center | 0.051 - 0.1525 | align=center | 0.835 - 2.499 |
| align=center | B | align=center | 0.1526 - 0.300 | align=center | 2.500 - 4.916 |
| align=center | C | align=center | 0.301 - 0.650 | align=center | 4.932 - 10.65 |
| align=center | FAI | align=center | max 1.526 | align=center | max 25 |
| align=center | Jet |