  Ultra-long gamma ray bursts (ULGRBs) are a distinct class of GRBs
characterized by durations of several thousands of seconds, about two orders of
magnitude longer than those of standard long GRBs (LGRBs). The driving engine
of these events has not been uncovered yet, and ideas range from magnetars, to
tidal disruption events, to extended massive stars, such as blue super giants
(BSG). BSGs, a possible endpoint of stellar evolution, are attractive for the
relatively long free-fall times of their envelopes, allowing accretion to power
a long-lasting central engine. At the same time, their large radial extension
poses a challenge to the emergence of a jet. Here we perform an end-to-end
simulation aimed at assessing the viability of BSGs as ULGRB progenitors. The
evolution to core collapse of a BSG star model is calculated with the MESA
code. We then compute the accretion rate for the fraction of envelope material
with enough angular momentum to circularize and form an accretion disk, and
input the corresponding power into a jet which we evolve through the star
envelope with the FLASH code. Our simulation shows that the jet can emerge, and
the resulting light curves resemble those observed in ULGRBs, with durations
$T_{90}$ ranging from $\approx$4000~s to $\approx10^4$ s depending on the
viewing angle.
