Having read too many submarine novels and lacking enough real information I’ve always taken it on faith that during fast descents and fast ascents the hull of the submarine will make popping and/or creaking noises due to the rapid pressure changes. SubmarineDopers, any truth to this?
On a related note, I’ve flown on many commercial aircraft that seem to make rather fast ascents (to my mind anyhow) but I’ve failed to notice any noises coming from the aircraft’s structure. Does this have something to do with how planes are pressurized? Or am I mixing apples and oranges?
Commercial aircraft are pressurized, so that’s not the issue. It’s more about the pressure differential. In the atmosphere, the total pressure differential from sea level to outer space is about 14.7 lb/sq. in. You can go up pretty high and the difference is small.
Water reaches the same pressure differential in something like 32 feet. Thus the pressure on a submerging sub is going to be greater than the pressure on an aircraft (and in the opposite direction).
Regarding pressure differentials, what RealityChuck said.
Yes, submarines make popping and creaking noises when changing depths. Submarine hulls are welded now, though, so no rivets pop out dramatically nowadays like in Das Boot.
A related effect is hull compression due to sea pressure. A string tied taut across the torpedo room on the surface will hang noticeably loosely at test depth.
The worst hull noise I ever experienced, however, was on the surface, driving into port in quite rough seas. The boat was experiencing 30-40 degree rolls, and every few seconds would crash into the next set of waves. The noise was deafening. I was convinced the boat’s keel was going to break before we made it in. (It didn’t.)
I would guess that the difference beween what you heard and what you expected had more to do with ambient noise. A plane that is climbing has the sounds of the engines, the sounds of the wind, and the sounds of the ventilation system to overwhelm any slight sound of rubbing aluminum. In addition, there is already a certain amount of insulation built into the passenger compartment of a commercial plane to prevent the sounds of the engines and wind from screaming through the compartment, so the noise you do hear is originally very loud, has been suppressed, and still makes it through to be audible. Against those noises, the creaking of a few aluminum joints just aren’t going to be loud enough to be heard.
In contrast, the only insulation on a submarine might be limited to what it takes to maintain temperature in the crew compartment and the noise is made by very large pieces of metal plate.
On a normal ship in high seas, the sound of the hull creaking is a constant background noise, so I would guess that it would be present on a submarine undergoing stress on the hull.
