Ground Influence on a Model Airfoil with a Jet-Augmented Flap as Determined by Two Techniques

An investigation was made in the Langley 300-MPH 7- by 10-foot tunnel with a conventional ground-board setup and in the Langley tank no. 1 by using the tow carriage to move the model over a ground board to evaluate the simulation of flight conditions in ground influence with a conventional ground-board setup. The 12-percent-thick airfoil was unswept and untapered with an aspect ratio of 6.0 and had a 10 percent- chord jet-augmented flap. From this investigation it appears that the loss in lift of an airfoil with a jet-augmented flap in ground influence as determined in a wind tunnel with a conventional ground-board setup is considerably larger than would be obtained in free flight.