At the launch pad, a space shuttle launch is obscenely loud - so loud, in fact, that they have a dedicated sound supression system to prevent the reflected sound waves from damaging the vehicle.
How about way back where the public is allowed to watch from? How does the sound level at that location compare to, say, an afterburner pass by the Blue Angels?
What about the Saturn V? Not a whole lot more thrust (7.7M pounds vs the space shuttle’s 6.8M pounds), but was it significantly noisier?
Saturn V rockets measured 220 db, while the space shuttle comes up at 215 on launch, but 220 with the sonic boom coming back,according to this site. Blue Angels more quiet, unless sonically booming.
OK, but the Blue Angels come to within ~1/2 mile of the spectators, whereas the space shuttle launch pad is maybe a few miles from the spectator area. So what’s the decibel level at the location of the spectators?
I watched the last launch from Titusville, about 11 or 12 miles away from the launch pads. The noise was loud enough that you would have had to shout over it, but not unbearably loud; I would estimate somewhere in the 100-110 dB range. Other public viewing areas are closer (6-7 miles), so the sound would be correspondingly louder there. I believe I read somewhere that the VIP launch spot is only three miles away from the pads.
The answer would appear to be 115db SPL. The reason is that the location of the viewing areas are located at a position where this level is not exceeded, as it is a level mandated by the Department of Labour Standards for maximum allowed levels for brief exposure. As noted above the levels nearer the launch are so loud that it starts to become something insane. Normal ideas about sound cease to apply. You would probably die too close to the launch.
This article, purporting to be one guy’s experiences recording the sound of a Shuttle launch, claims that:
In the spring of 1962, I was a witness to a test firing of the Atlas rocket at Redstone Arsenal in Huntsville, Alabama. We were in underground bunkers to protect us from the soundwaves which would have knocked us down if we had been outside. Yet we could see and hear what was going on with the rocket. We were close enough that our guide was able to point out Werner Von Braun when he entered a building which was several yards in front and to the right of the bunker.
The Atlas never left the launch pad, but I don’t know what in heaven’s name could have held it down. The sound was unbelievable and remains the loudest thing I’ve ever heard. It was an unimaginable blast. I do remember that I could scream or shout at the top of my lungs or from the bottom of my diaphragm and not make myself heard to myself.
What?
Tripolar, if Zoe is a woman, I don’t think shes talking about a birth control device.
Interesting but unexplored point.
How could someone die from sound? Bleeding out through the ears? Chest compression leading to suffocation? Single blow creating heart attack?
Related quiestion, if so loud then how do they protect crews of mobile missiles like the SS-25 ICBM? Or Scuds. How loud is it inside a boomer when an SLBM launches?
The SLBM engine only ignites once the missile clears the water surface. The actual “launch” from within the sub is done by compressed gas.
From 3 miles away, where I watched my last one, REALLY LOUD!! Teeth rattling loud.
The source sound pressure level (SPL) experienced near an operating rocket engine are in excess of 140 dB at a reference pressure of 20 micropascals (gauge) across the frequency spectrum (usually considered to be 50 to 10,000 Hz). This translates into an energy content that is equivalent to a value greater than 10 g[SUB]rms[/SUB]. That is, it is somewhat akin to being suddenly subject to an acceleration of 10 times what you experience on Earth’s surface. In addition, the acoustic field can couple to nearby features, amplifying the pressure fluctuations and in extreme cases creating overpressure shock waves, similar to that of a detonating explosive, and causing physical trauma. And the frequency of fluctuation can cause problems as well; at the right frequency that couples to natural modes of the heart, sinuses, or circulatory system, the pressure can cause disruptions of normal physiological functions, resulting in heart disrythmia or other problems.
Nitpit to an otherwise essentially correct explanation: the missile is ejected by steam generated from a gas generator at the base of the tube, not compressed gas. The impulse of this ejection makes the entire boat shudder in response. You are correct that the first stage motor is not ignited until it is aloft.
Stranger
I was on the NASA Causeway for a shuttle launch. It was the standard non-VIP, pay-for-a-ticket observation point. The distance from the launch pad is about 6 miles / 9 km. It was an August late-afternoon, hot and humid.
The ascending shuttle appeared as a fuzzy bright dot. It took several seconds to get the sound, of course.
The sound itself was quite bearable. Like a continuous string of fireworks going off, I’d say. No need to covers my ears or anything.
I also was a the Causeway for a Space Shuttle launch, sitting on stands. It’s a loud sound (25 seconds late) but a rumble and not higher-pitched like a jet engine.
Loud but completelt tolerable.
So what would have happened to onlookers if a rocket suffered a catastrophic launch.
Let’s say a Saturn 5 blew up on the launch derrick, that’s an awful lot of rocket fuel/energy, would the onlookers have been in danger from blast/thermal effects?
General public, they may feel heat flash but probably not enough for burns – that risk’s likely to have been calculated into the safe distance figure for the public viewing spots. IMO they’d be more at risk from flying burning debris/fuel spray/toxic cloud. It’s a lot of fuel but it’s kept in a series of closed tanks so it’s not certain the whole megillah would go off instantaneously or at optimal mix for a flash blast.
When one Soviet N-1fell back onto its pad and blew up it the US monitoring networks described it as the equivalent of a small nuke. Obliterated the launch pad.
I was a member of the press at the first launch of the Space Shuttle in 1981. As I recall, the press viewing area was on the edge of the aptly-named Mosquito Lagoon, around 3.6 miles from the launch pad. I remember the sound being loud, but not so loud that you couldn’t talk. It sounded like a giant Roman Candle.
It’s pretty well known that when the first Saturn V launch occurred (it was Apollo 4, unmanned) they didn’t have the noise suppression system in place, and the ceiling tiles in the Cape’s CBS studios started falling on Walter Cronkike!
I know that. But the boat is only 150 feet below the surface wnhen launching and water is a very good conductor of sound.
And again, what about the protection for crews of mobile missiles like Pershing II, Scuds, SS-25 etc?