  We examine SDO/EVE data to better understand solar flare irradiance, and how
that irradiance may vary for large events. We measure scaling laws relating
GOES flare classes to irradiance in 21 lines measured with SDO/EVE, formed
across a wide range of temperatures, and find that this scaling depends on the
line formation temperature. We extrapolate these irradiance values to large
events, exceeding X10. In order to create full spectra, however, we need a
physical model of the irradiance. We present the first results of a new
physical model of solar flare irradiance, NRLFLARE, that sums together a series
of flare loops to calculate the spectral irradiance ranging from the X-rays
through the far ultraviolet (~ 0 to 1250 Angstroms), constrained by GOES/XRS
observations. We test this model against SDO/EVE data. The model spectra and
time evolution compares well in high temperature emission, but cooler lines
show large discrepancies. We speculate that the discrepancies are likely due to
both a non-uniform cross section of the flaring loops as well as opacity
effects. We then show that allowing the cross-sectional area to vary with
height significantly improves agreement with observations, and is therefore a
crucial parameter needed to accurately model the intensity of spectral lines,
particularly in the transition region from 4.7 < log T < 6.0.
