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X-15 attached to its B-52 mother ship with a T-38 flying nearby. The X-15 had a thick wedge tail to enable it to fly in a steady manner at hypersonic speeds. [16] This produced a significant amount of base drag at lower speeds; [16] the blunt end at the rear of the X-15 could produce as much drag as an entire F-104 Starfighter. [16]
At Mach 0.65, u is 65% of the speed of sound (subsonic), and, at Mach 1.35, u is 35% faster than the speed of sound (supersonic). An F/A-18 Hornet creating a vapor cone at transonic speed just before reaching the speed of sound. The local speed of sound, and hence the Mach number, depends on the temperature of the surrounding gas.
Dimensionless numbers (or characteristic numbers) have an important role in analyzing the behavior of fluids and their flow as well as in other transport phenomena. [1] They include the Reynolds and the Mach numbers, which describe as ratios the relative magnitude of fluid and physical system characteristics, such as density, viscosity, speed of sound, and flow speed.
Twelve pilots flew the X-15 over the course of its career. Scott Crossfield and William Dana flew the X-15 on its first and last free flights, respectively. Joseph Walker set the program's top two altitude records on its 90th and 91st free flights (347,800 and 354,200 feet, respectively), becoming the only pilot to fly past the Kármán line, the 100 kilometer, FAI-recognized boundary of outer ...
The external tanks were jettisoned 67.4 seconds after launch at a speed of Mach 2.0 and 70,000 feet. The total engine burn time during the flight was 141.4 seconds. After Flight 188, 11 more X-15 flights were made before the program was retired. The X-15 program data was used in the planning of future aircraft and spacecraft designs.
Conversion of the Mach unit of speed depends on the altitude at which the speed is measured. That altitude should be specified either in feet (for example, |altitude_ft=10,000 ) or in metres (for example, |altitude_m=3,749 ).
The subsonic speed range is that range of speeds within which, all of the airflow over an aircraft is less than Mach 1. The critical Mach number (Mcrit) is lowest free stream Mach number at which airflow over any part of the aircraft first reaches Mach 1. So the subsonic speed range includes all speeds that are less than Mcrit.
In November 1961, Air Force Major Robert White flew the X-15 research aircraft at speeds over Mach 6. [4] [5] On 3 October 1967, in California, an X-15 reached Mach 6.7. [6] The reentry problem of a space vehicle was extensively studied. [7] The NASA X-43A flew on scramjet for 10 seconds, and then glided for 10 minutes on its last flight in 2004.