Rotating detonation engines (RDE) are currently being investigated to implement pressure-gain combustion thermodynamic cycles. Pressure-gain combustion-based cycle could provide significant improvements over conventional isobaric burners. For practical applications, the knowledge of the heat flux to the wall in such combustor is requirement for the design of any thermal management solution. The flow field in RDE combustors greatly differs from than of conventional combustors and as such yield vastly different heat fluxes distributions in the chamber. Very few experiments have attempted to record both the flow field and the heat flux on such engines. In this work, parametric experiments are conducted on a 100 mm diameter RDE. The engine is operated with mixtures of natural gas/oxygen at mass flow rates ranging 100 to 500 g/s and varying equivalence ratio using two different injector plate design. Calorimetry experiments provided an axial resolution of the heat flux on the outer wall and demonstrated steady state is reached within 2 s in most conditions. A heat sink version of the combustor is also operated with a side optical access. The recording of the channel-integrated chemiluminescence is processed using the velocity-compensated method to provide a time-resolved detonation flow field along the full combustor height. The flow fields obtained are then used to analyse the heat flux distributions obtained.