The Mark 4 Eagle is the 22 inch model, first seen in Breakaway and used throughout the series. Initially most of the launch pad shots used the 22 inch Eagle; these shots were repeated throughout the series. Otherwise, as more 44 inch Eagles were built, the 22 inch was featured less, appearing only in more distant shots (as well as library shots on launch pads).
A second 22 inch Eagle appears rarely in Year 2.
It appears in these flypast shots with the first 22 inch Eagle alongside in Brian The Brain. Both Eagles were filmed twice in each shot, creating the impression of 4 Eagles.
This shot from The A B Chrysalis features two 44 inch Eagles (appearing twice each), with both 22 inch Eagles beyond- the original 22 inch (with booster pod) appears 4 times, the 2nd 22 inch appears 3 times.
It also appears in a number of publicity shots for The Bringers Of Wonder, but none of these shots appear in the episode.
Copyright Martin Willey