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