A view of the second stage's LR-91
rocket engine nestled inside of the interstage structure.
The visible part of the engine primarily consists of the ablative skirt (see
dsc46348.jpg, dsc46411.jpg, and dsc46428.jpg for
details as to how the ablative skirt is bolted to the engine). Toward the
center of the interior of this nozzle extension can be seen the regenerative cooling tubes of
the engine proper.
The display is fitted with color-changing LEDs which illuminate the interior of
the thrust chamber to suggest engine firing.