Related Clues:

• Flying speed ratio
• Physicist Ernst
• Airspeed measure
• Sound-speed number
• Speed-of-sound word
• __ 1: speed of sound
• ___ 5 (Speed Racer's car)
• Ernst of sound-barrier fame
• Speed of sound
• St. ___ Girl
• Russian emperor after Catherine II
• 1945 Physics Nobelist
• Name often followed by a number
• The speed of sound
• St. __ Girl beer