MINtSTRY OF AVtATtON

SUMMARY Wind tunnel tests have been done on two families of slim delta aerofoils, having 70° and 80° leading edge sweep. It is shown that by employing a certain type of transverse cross section (having spanwise camber) it is'possible to reduce the lift-dependent drag below that appropriate to an aerofoil with symmetrical sections. The present tests indicate very considerable reductions in the lift-dependent drag for the transversely cambered delta, in some cases to little more than half that of a symmetrical delta having the same planform. While it is not clear how muoh of this reduction is due to the favourable suction on the forward facing parts of the cambered delta and how much may be due to some of the other features inevitably incorporated into the models (such as positive fore and aft oamber towards the rear), it is felt that the evidence is suffioiently strong to show that the phenomenon investigated does lead to significant reductions of drag at high lift and therefore might in some designs be exploited to advantage.