There are two very important small orthogonal spaceships:
The G is c/2, the R is 2c/4. There exist G guns for all possible periods, the lowest being 11. The same is true for the R gun, but no guns have ever been found of periods 9 and 10, the former being the lowest period possible.
Next to c/2 orthogonal, known spaceship speeds are 2c/6 orthogonal, 2c/19 orthogonal and 2c/12 diagonal, with the smallest examples being:
The latter two spaceships have since appeared naturally in C1 soups, and have a synthesis from G's. For all known speeds there are puffers, but only the orthogonal speeds have rakes.
- Snowflakes (discussion thread) at the ConwayLife.com forums