The 1967 Apollo 4 Mission was an unmanned flight to test that Saturn v Rocket as a viable launch vehicle for future manned missions. The test was a resounding success and a crucial step in the US space program. But the Saturn V was also incredibly loud — so loud that it was rumored that the acoustic energy was enough to melt concrete. That’s not the case, according to an August article published in a special issue of the Journal of the Acoustical Society of America (JASA).
“The Saturn V has assumed this legendary, apocryphal status,” said co-author Kenneth Gee of Brigham Young University. “We felt that as part of the JASA special edition on acoustics education, this was an opportunity to correct misinformation about this vehicle.” In addition to the authors’ analysis, the paper contains several problems for the students to solve related to the event – including a tongue-in-cheek problem involving making an acoustic temperature grilled cheese sandwich.
German rocket scientist Wernher von Braun, who had helped build the V-2 rocket, came to work for NASA in 1945 as part of Operation Paperclip. His job was to share his accumulated knowledge with the Army’s Missile Division. But when the Soviets launched Sputnik 1 in 1957, priorities shifted and von Braun’s team was tasked with developing an equivalent US missile. Juno 1 launched the first US satellite in January 1958 and served as the prototype for the Saturn series for use in Earth orbit and lunar missions.
The Apollo 4 mission launched on a Saturn V on November 9, 1967 at 7 a.m. EST. When the five F-1 engines ignited eight seconds before liftoff, the sound pressure generated was so strong that the waves shook the Vehicle Assembly Building, Launch Control Center and press buildings, even though the launch pad was more than 5 kilometers away. a way. CBS reporter Walter Cronkite and his producer had to hold on their trailer’s observation window when ceiling panels fell to the ground, fearing they would break from the noise. Cronkite later claimed it was the scariest space mission he’s ever covered. As an observer of a Saturn V launch described it:
“It’s like continuous thunder, and when you think it can’t get any louder, it does. I remember the vibration seemed to get into my bones… The bird soars, the flames belch, and the thunder goes.” on and on it gets louder and louder it rises and finally resolves into a sound like a billion sheets of heavy paper being torn lengthwise for a full minute.”
Something so memorable would lead to some exaggerated claims and unfounded rumors for decades to come. My goodness et al. conducted a review of online forums and discussion boards and were dismayed at the amount of disinformation that had been circulating there. In addition to claims that the sound level was sufficient to melt concrete, there were claims that it “set grass ablaze a mile away” and was powerful enough to “ignite the hair of bystanders” and “elevate rainbows from the sky.” to blast the sky”. According to the authors, “Such claims inspire awe at the power of the vehicle that propelled humans to the moon, but are nonetheless based on a flawed understanding of the true acoustic environment.”
Their analysis of this acoustic environment includes NASA footage of the Apollo 17 launch—digitized by the Discovery Channel for a 2008 documentary—in which sound waves can actually be seen shortly after the engine fires, due to the humid atmosphere and backlighting. Their physics-based model put the sound level at 203 decibels. Per gee, 170 dB is equivalent to 10 aircraft engines, while 200 dB is equivalent to 10,000 aircraft engines.
Considering the human pain threshold is around 130dB, that’s pretty loud. It just wasn’t loud enough to melt concrete or set grass on fire. My goodness et al. Think the myth grew out of the confusion between sound power (comparable to the power of a lightbulb) and sound pressure (similar to the brightness of a lightbulb). This would lead to erroneous attempts to calculate the acoustic power of a Saturn V launch. If reports of burning grass or melting concrete turn out to be confirmed, it’s more likely to be caused by radiant heat from the cloud or debris – not the sound of the Saturn V.
DOI: Journal of the Acoustical Society of America, 2022. 10.1121/10.0013216 (About DOIs).
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