Laminar-turbulent transition is critical for vehicles which fly at hypersonic speeds for extended periods. To improve on existing correlations, prediction meth-ods that incorporate knowledge of the transition mech-anisms are necessary and now feasible. Purdue contin-ues to develop the Boeing/AFOSR Mach-6 Tunnel to seek quiet flow at high Reynolds number, with noise levels comparable to flight. The loss of quiet flow above 8 psia stagnation pressure is probably not due to fluctuations exiting the driver tube, since preliminary measurements show these are comparable to those in the Langley Mach 3.5 quiet tunnel. Studies of the effect of downstream disturbances show that separa-tion is more likely for a laminar nozzle-wall boundary layer, as expected; there is still no evidence that such disturbances can trip the upstream boundary layer. An eighth bleed-slot insert was designed and tested, but was not useful, since the suction massflow was too large to maintain a sonic throat. A porthole window has been completed for high Reynolds number opera-tion to 6 × 10 6 /ft., which should enable temperature-sensitive paints measurements of blunt-cone transition induced by surface roughness. Finally, preliminary hot-wire measurements appear to show second-mode instability waves on a blunt cone at 235 kHz.