F-35 JSF's Surprising Sonic Boom


A couple of months ago I was fortunate enough to spend a day with a NASA and Air Force test team in the Mojave Desert near Edwards AFB. The day involved testing a small unmanned air vehicle equipped with an automatic ground collision avoidance system, with the intent of showing that – no matter how hard we tried to crash the UAV – the system would prevent us from doing so. I will post a separate blog about this program in the next few days.

However, the day was also eventful for me in other ways. Having spent many years now reporting on goings on in the high desert, and been bombarded by sonic booms on several occasions, I was not surprised or disturbed by the constant barrage of booms that echoed around the area as we conducted the UAV testing. After all, we were in the heart of the R-2508 Edwards test range complex, and right beneath the Black Mountain low level supersonic corridor (marked in red circle below). 

This part of the range gives pilots the rare chance to conduct supersonic operations overland for a short distance at altitudes as low as 500-ft in some parts, quickly rising to 10,000-ft and above only. The Black Mountain route adjoins the midway point of the 224 nautical mile long high altitude supersonic corridor that straddles the range complex from east to west. I was once lucky enough to travel along the high altitude route at Mach 1.3 in an F-16, performing an aileron roll while doing so.  

Although F-15s, F-16s and F-22s crossed overhead several times during the day, barely visible against the blue sky, a high layer of cloud moved across part of the sky later in the afternoon which provided a backdrop for viewing the fast moving traffic. At one point an F-35A Joint Strike Fighter from the F-35 Integrated Test Force at Edwards was using the low level corridor with an F-16 chase for company.

I noticed the F-35A high up (as this zoomed in spot on my photo above indicates), but refocused my attention on trying to film the UAV as it performed its automatic collision avoidance maneuver. Note how the shock of the boom, which was unexpectedly severe at our location, causes the video to jump slightly at 7 sec. For comparison on the relatively lower boom intensity listen for the double-boom of the decelerating F-16 chase at 18 sec. I am sure someone must know, but does the intense boom represent an acoustic facet of the F-35’s low-observable design and parallel leading and trailing edge alignment?

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