Abstract: The invention improve hot air balloons of the type using heavy duty propane burners producing large unconfined flames by manually controlled intermittent short combustion periods,--the type used for the sustained flight and transport of one or more passengers. The improvements comprise increased lift and rate of lift, fuel economy, safety of components and passengers, envelope life, and elimination of scorching and near-scorching of the envelope and skirt, reduced cumulative deterioration of the envelope; these improvements are accomplished by the elimination of the hiterto unrecognized large loss of radiant energy from the flame which has passed through the transparent gas and translucent portions of the envelope (thin, light colored) and being lost without having heated the interior gases,--by means of opaque shields of metal and/or fabric suspended between the flame and the envelope to intercept the radiant energy, convert it to heat energy and transfer it to the contiguous gases.