A few years ago the United States Air Force became interested in developing a higher temperature version of its standard pitot-static tube capableA of accurate operation to Mach number 5 and 150 000 ft with angles of attack up to 14°. It soon became evident that the existing aerodynamic configuration was inadequate because (a) the sharp pitot pressure source could not be protected from high heat fluxes and temperatures, (b) the static pressure source geometry produced serious errors at Mach numbers above 3·0 for α> 5°, and (c) the static pressure source geometry could be responsible for unacceptably high lag above 100 000 ft altitude because it consists of two orifices of only 0·070 in diameter.