Passive devices for axisymmetric base drag reduction at transonic speeds

Experiments have been made to assess the effectiveness of several base modifications or passive devices for reducing base drag and total afterbody drag at transonic speeds. The modifications tested include base cavities, ventilated cavities, and two vortex suppression devices. Results show that, while appreciable base drag reductions are possible with many of the devices examined, the net total drag reductions are relatively lower, presumably because of the additional losses associated with the devices. (Author)