Sonic Boomless - How To Bring Supersonic Flight Back To The Future
0:04 Boom Supersonic's XB-1: Boom Supersonic is testing the XB-1, a supersonic demonstrator aircraft, as a stepping stone to their "Overture" airliner, aiming for "boomless" supersonic flight.
0:40 Supersonic Flight Ban & Public Perception: Supersonic flight over the US was banned in 1973 due to sonic boom concerns. The CEO of Boom is promising overland flights with no sonic boom on the ground.
1:11 Sonic Boom Refraction: The phenomenon of refracting sonic booms upwards, preventing them from reaching the ground, is well-known. It relies on the changing speed of sound with altitude. The aircraft needs to fly slower than the speed of sound at ground level.
1:15 NASA's X-59 Quest: NASA's X-59 Quest is a separate project, specifically designed to produce a quieter sonic boom ("sonic bump").
2:02 Sonic Boom Basics: Sonic booms are caused by objects pushing air out of the way faster than the air can move, creating shock waves. Engine noise is not a requirement.
3:15 Schlieren Imaging: Scientists use Schlieren imaging to visualize these shock waves, revealing areas of high air density.
4:13 Sonic Boom "Carpet": The sonic boom effect extends sideways from the aircraft's flight path, not just directly underneath.
4:32 Early Testing in Oklahoma In the 1960's, the effect of sonic booms on civilians was tested in Oklahoma City, resulting in the 1970's ban.
6:15 N-Waves and Shock Wave Merging: Classic sonic booms are "N-waves" with sharp pressure rises. Multiple shock waves from an aircraft can merge into these N-waves.
7:23 Falcon 9 Triple Sonic Boom: A recent paper explains the Falcon 9 booster's triple sonic boom as shock waves merging.
7:37 Low-Boom Design Strategy: Low-boom aircraft design aims to create many small, non-merging shock waves.
8:15 Shaped Sonic Boom Demonstrator (SSBD): NASA's SSBD used an F-5 with a modified nose ("Pelican nose") to generate weaker, evenly distributed shocks.
8:35 Measuring the Shock Waves To validate wind tunnel data, chase planes flew inside of the shock cone to take measurements.
9:04 Gulfstream's Quiet Spike: Gulfstream's "Quiet Spike" (a protruding nose extension) also aimed to create weaker shocks, but the rest of the aircraft still generated strong waves.
10:05 FAA Regulations: Current FAA rules restrict supersonic flight based on speed, not ground noise levels.
10:30 Simulating Soft Sonic Booms: NASA developed a technique using F-15/F-18 aircraft in a specific dive maneuver to create soft sonic booms for community testing.
11:37 Galveston Study (2018): NASA conducted a community study in Galveston, Texas, using these soft sonic booms to gauge public response.
12:00 X-59 Design Features: The X-59 has a very long nose (over 1/3 of the aircraft's length), flattened and elongated to shape the sonic boom. The pilot relies on cameras due to the nose obstructing forward vision.
13:01 Engine and Air Intake A single GE f414 Turbo Jet engine is used, as found in the Super Hornet. The air intake is located above the aircraft to help direct shockwaves upward.
14:00 Goal of the X-59: The X-59 aims to demonstrate low-energy sonic booms that are acceptable to the public, potentially leading to the FAA changing regulations from speed limits to sound limits.
14:20 Hope for the future If sound limits are adopted, it paves the way to bring back supersonic airliners.