  We present the results of a Monte Carlo simulation of the $RP^2$ model in
three dimensions with negative coupling. We observe a second order phase
transition between the disordered phase and an antiferromagnetic, unfrustrated,
ordered one. We measure, with a Finite Size Scaling analysis, the thermal
exponent, obtaining $\nu=0.784(8)$. We have found two magnetic-type relevant
operators whose related $\eta$ exponents are $0.038(2)$ and $1.338(8)$
respectively.
