Radiant heat output has been measured from an MTV flare composition for masses between 0.2 and 36kg. Around 30% of the heat of reaction is lost as radiation. The maximum temperature at the surface of the fireball is estimated to be around 1800K. The effect of distance on the received radiated heat dose is complex but, with large buoyant fireballs, the attenuation might be as small as the inverse of distance.