OPTIMUM AIRFOILS AT MODERATE SUPERSONIC SPEEDS. PART VI. BASE DRAG EFFECTS ON THE MAXIMUM LIFT-TO-DRAG RATIO FOR GIVEN THICKNESS,
Abstract
Maximum lift-to-drag ratio airfoils at moderate supersonic speeds are determined using Ackeret's linear theory for the forebody pressure coefficient and Chapman's experimental results for the base pressure coefficient. The case of given length and thickness is investigated for both laminar flow and turbulent flow. It is shown that the maximum lift-to-drag ratio airfoil is identical with the minimum drag airfoil. Furthermore, for turbulent flow and given Mach number and Reynolds number, two critical values of the thickness ratio exist, tau 1 and tau 2. For tau < or = tau 1, the optimum airfoil is a diamond shape with a closed trailing edge and exhibits maximum thickness at midchord; for tau 1 < or = tau < or = tau 2, the optimum airfoil is a diamond shape with a blunt trailing edge and exhibits maximum thickness between midchord and the trailing edge; finally, for tau > or = tau 2, the optimum airfoil is a wedge and exhibits maximum thickness at the trailing edge. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 1968
- Accession Number
- AD0838382
Entities
People
- Robert E. Pritchard
Organizations
- Rice University