This entry describes the experimental work conducted in the Department of Aeronautics at Imperial College in connection with Test Problems 1 and 2 of the "Workshop on Hypersonic Flows for Reentry Problems, Part I". These are defined as follows: Test Problem 1 Flow Over a Slender Cone Test Problem 2 Turbulent Base Flow The main requirement of this text is to present the experimental data for direct comparison with the predictions of CFD codes. We have therefore concentrated mainly on a factual statement of measuring techniques and results, together with an assessment of experimental accuracy. Future publications will be devoted to more extensive physical interpretations and discussions of the results. We have produced a large volume of data, some of which were categorised as "MANDATORY" and some as "OPTIONAL" for the purposes of CFD validation. However, only the "MANDATORY" data are presented here, although the other data are available and will be published separately later. 2. EXPERIMENTAL ARRANGEMENT 2. 1 The Test Facility The experiments were conducted in the Imperial College No. 2 Gun tunnel. This facility is a conventional intermittent blowdown tunnel with a contoured Mach 9 (nominal) axisymmetric nozzle fed by a free piston compression heater. The operating condition under which the data contained in this report were obtained is presented in Table 1. Test 2 T (o K) M b. Mlm Po (N/m ) Re/m T (o K) IX) IX) Case IX) w 1. 1 7 7 +0. 14 9. 16 6. 67×10 5. 5xl0 59.