Long Project Description

Music is all around us. It is crucial to most of our lives. But everyone’s exposure to music shouldn’t end at listening. Many studies have shown that people who play music are more intelligent in several fields such as math, reading, spatial skills, and memory. These increases in intelligence also increase as people practice music more often. This means that it would be incredibly useful to our education systems if every student were able to play a musical instrument. Unfortunately, with music programs in schools being quickly defunded, this goal is slipping away. With today’s economy, people just can’t afford to buy their children or themselves a good instrument. And if they can’t afford an instrument that sounds good then they decide that there’s no point to playing an instrument and they just don’t bother. Even if a family can afford to buy their child an expensive instrument, they may not trust them with such an expensive item because instruments are usually fairly delicate objects.

That’s where I come in. I have an idea for an instrument that would sound good, perform well in harsh environments, and be relatively cheap. I want to create a carbon fiber trumpet. Let’s look at the first part of this: sounding good.

Traditionally, trumpets are made out of brass. The problem is that brass is very heavy (high density) and soft (low stiffness/modulus of elasticity) which means it isn’t very good at transferring vibrations. Instead it dampens them. Carbon fiber reinforced plastic (CFRP), on the other hand, is very light (low density) and very stiff (high modulus of elasticity). This means a trumpet made from CFRP would most likely require less energy to play and would be louder because it wouldn’t stifle vibrations as much as brass. [UPDATE: Take this paragraph with a grain of salt until I have actually tested this. I have seen conflicting data on cfrp's sound dampening. Some sources say it absorbs vibrations like crazy and some say it transmits vibrations like crazy...]

One important aspect of an instrument sounding good is that it is in tune. When brass instruments go into different environments they change size. This is due to the fact that brass has a fairly high coefficient of thermal expansion. When the brass tubes expand, it makes the instrument longer, thus making the instrument flat. The instrument then has to be retuned or else it will sound horrible. CFRP generally has a much lower coefficient of thermal expansion than brass. This means that you could just tune it once and the changes with different temperatures will be so minor that you can basically ignore them. This is important for beginners who often have a hard time figuring out whether they in tune with others or not. [UPDATE: There is also conflicting data on this. The coefficient of thermal expansion for cfrp seems to depend more on the specific material than cfrp in general. Sometimes it's coefficient of thermal expansion is much lower than that of brass, but sometimes it is similar or slightly higher.]

Marching band is a large part of many high school bands. Having an instrument that is light-weight is very important. Carbon fiber has a very high strength to weight ratio, meaning that a CFRP trumpet would weigh far less than a brass trumpet. It would weigh less than half the weight of a brass trumpet.

It would also be much stronger than a brass trumpet, which is very important because beginners are likely to drop their trumpets a few times in their lives. CFRP doesn’t dent, when it breaks it breaks completely. This means that if it is damaged it has to be fixed and cannot be played with a bad sound from dents. Beginners may not notice a dent or bend they accidentally create that would be detrimental to their sound.

One of the most annoying parts of playing trumpet is that it fills up with condensation. Because trumpets are made from brass, they transfer thermal energy really well. This means that as your hot humid breath passes through the instrument, the water vapor condenses into liquid. If you are playing outside in the cold, you have to empty your spit valve after about 10 minutes of playing or else it sounds like you’re humming through a straw in a cup of water. Carbon fiber often has a lower thermal conductivity than brass which means it will take away less heat from the air, and therefore create less condensation.

Wait a second, isn’t carbon fiber that ridiculously expensive material they make fancy airplanes out of? How do you expect me to believe it would make a cheap trumpet? Well it’s simple really. Carbon fiber is extremely expensive by weight, but since it’s so much stronger by weight than traditional materials, you also don’t need nearly as much. So it ends up being only slightly more expensive than brass. The reason why it makes a cheaper trumpet is that trumpets are quite difficult to make out of brass. They require skilled craftsmen to coax it along every step of the way, so by the time your trumpet is finished, it’s been marked up 2000% above the price of materials. Carbon fiber is much easier to build with than brass is. All you need is one mold for each piece and then you can make as many as you want for just a little more than the price of materials. That would take the cost of a trumpet much lower, hopefully to a level that a lot more people can afford.

I plan to make every part of this project completely open source. I will release design files, build logs, and eventually detailed instructions about the build.