A friend claims that the neck of his guitar broke during a flight because he failed to loosen the strings and the lower air pressure at altitude did something nefarious to his six-stringed buddy. I suspect that the effects of changes in air pressure are negligible when one considers that a tuned acoustic guitar can have in the vicinty of 150 lbs per square inch of tension on the necks (can’t remember where I picked up this figure- I guess I could dig if I have to cite). I expect that the damage to the instrument had more to do with careless handling and less to do with air pressure.
I think it’s more to do with the temperature which can get below freezing in flight. The strings will contract and yes, many guitars have been broken this way.
Yeah, it’s the cold and careless handling. It isn’t going to be air pressure because there is a big old hole in the body which will allow the guitar adjust to the different air pressure. As long as the pressure inside the body and outside stay basically the same there isn’t going to be a problem.
Yeah, it’s the cold and careless handling. It isn’t going to be air pressure because there is a big old hole in the body which will allow the guitar adjust to the different air pressure. As long as the pressure inside the body and outside stay basically the same there isn’t going to be a problem.
It’d have to get VERY cold for the strings to contract enough to break the neck. (BTW, the neck is not in tension, but compression.) I havn’t noticed more than moderate change in string tension going from my 70 degree house to my 0 degree car (sensed as de-tuning) over several years. So while the temperature fluctuations are not good for it, (and I haven’t had any of my stuff down to -40), I’m thinking poor handling. Definitely not atmospheric pressure.
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When I have a bit more time, I’ll try to whip out a bit of math, if no one beats me to it.
OK… Tension goes up proportional to the square of the change in frequency, thus going up one octave, doubling the frequency, tension goes up by a factor of four. I think.
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Thus, if the frequncy rises by 1/2 a step, which is a factor of 1.0594, then the increase of tension would be about 1.1225, or 12.25%. Your guitar would probably survive this degree of increased tension, although it might make it more susceptible to damage from poor handling.
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All this is pulled out of (possibly faulty) memory; I would welcome correction if nessessary. It should also be remembered that there are other factors at work, most notably movement/changes of the wood due to environmenal changes.
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I don’t think I’ve ever seen a pitch swing that large due to temperature in any of my instruments.
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By the way, for those interested, I just found a nice article an string tension.
I neglected to address total string tension. The OP posits “in the vicinty of 150 lbs per square inch of tension on the necks”, but it’s not so high as that, and not those units. I picked a D’Addario light steel string set to get the tension data: total 85.2 lbs. Most other light steel sets will be similar. Medium and heavy will be somewhat higher.
I’d blame the low humidity - my violin always sounds crap for a day or two after flying, and I always take it as hand baggage so none of the other explanations would fit. The strings often spring loose, as well (note that a violin’s pegs work on friction alone, unlike a guitar’s). And yes, the humidity will have an effect very quickly.
Where is the guitar located, outside the body of the airplane? One of the biggest fallacies that still goes around is that the cargo compartment of airplanes is a cold unpressurized area of the airplane. This is false. The cargo compartment of all pressurized airplanes are pressurized and in many cases, are warmer than the air that circulates through the passenger cabin. When you are sitting in an airplane, the only thing between your feet and the cargo area is a piece of carpeting, a composite floor panel about 7/16 inches thick and a fiberglass cargo liner panel which are about .10 inches thick. The crew rest of early model 777’s is located in the aft cargo compartment.
Yes but on many airplanes the cargo compartment can get VERY cold, especially on long trips. Live animals are only allowed to be carried in cargo compartments that can be heated. This is usually the forward cargo compartment, and heating of the compartment is (or was, depending on the model of aircraft) controlled from the cockpit with the “dead cat” switch. Forget to turn it on and Fluffy is a popsicle by the time you get to your destination.
I know you mentioned that some compartments receive warm air, but I just wanted to make sure that people understand the difference: All cargo compartments are pressurized. NOT all are heated.
I never noticed a major difference in mine, but that’s probably because I’m a crappy player.
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I’d expect the humidity change to have a very rapid effect on a violin corpus where the material is thin and not sealed on the inside, but not the guitar neck, where the volume to surface ratio is much higher. Of course, your violin is more susceptible to much more rapid change because of its smaller size. You sound like a good candidate for an in-the-case humidifier, assuming you don’t already have one.
It would still be a guess but,…
a few questions first…
Hard shell Travel or soft case?
Where on the neck did it break?..the headstock or along the fretboard?
Where on the airplane was it stored?
Glued joint or bolt on neck?
what kind of Bridge?
does the neck have a steel truss rod?
(name and model and year of manufacture of the guitar will do…)
The same air that heats (actually cools) the passenger cabin heats (once again, cools) the cargo compartment. There has never been any kind of separate “heater” for the cargo compartment air. I have worked at Boeing since the 727 was in production and I can speak with confidence Boeing has never had a “dead cat” switch anywhere on any of their airplanes. The air cycled for equipment bay cooling in dumped into the cargo compartment which usually result in the cargo areas being warmer than the passenger compartment. That is why pets are usually loaded into the aft cargo of the airplane, it’s temperature is the same as the passenger compartment. There is nothing to seal the passenger compartment from the cargo areas. Remove the sidewall or air grille from any commercial aircraft (Boeing, M/D, or Airbus) and you will find holes in what is called the intercostal which leads to the cargo areas. I am going to print out this thread and show it to some of the engineers I work with. Misinformation such as this always gives them a laugh. If it was possible (Boeing has a problem posting drawings online), I could show airflow schematics of how the air is designed to travel throughout the fuselage. And in most circumstances, the air in the passenger cabin and cargo areas is cooled, 350 bodies in a fully loaded 747 create lots of heat.
racer the switch I referred to IS the switch that directs avionics cooling air into the cargo compartment (or not). On the 727 FE panel it was located on the top, usually with labels by bored crewmembers such as “Dog” (on) and “Cat” (off).
Not going to get into an engineering or construction debate with you.
