Due to the epoxy matrix of the composite material, the composite shaft has an inherent vibration dampening characteristics.
For a fixed diameter and length, a custom, engineered BAC carbon shaft will have a higher critical speed than steel, aluminum and titanium shafts. This is due to the low mass density of the carbon fiber/epoxy and the relatively high axial stiffness of the engineered laminate. This results in a shaft that can operate several thousand RPMs higher than a metal shaft of the same diameter and length. Some of the shafts pictured above operate in excess of 20,000 RPMs.
A custom engineered BAC shaft is the lightest weight shaft available. In some cases, depending on the size of the metal shaft being replaced, a BAC carbon shaft can eliminate several pounds of rotating weight.
For the same fixed diameter and fixed length, it is possible to engineer a carbon shaft to have a relatively low modulus of rigidity resulting in a shaft with a high torsional flexibility compared to the same size metal shaft. This unique characteristic will "smooth out" and absorb torque spikes extending the transmission life.
Since a BAC composite shaft does not have any welds, there is no metal fatigue. The life cycle of a properly designed composite shaft will far exceed all types of metal shafts since carbon fiber composite has extraordinarily high fatigue strength. The typical fatigue failure location of metal shafts is in the weld area (heat affected zone).
All BAC engineered composite shaft designs are lab tested to failure. One such test is the Ultimate Torsional Test which is conducted to verify the analysis. An engineered BAC composite shaft will exceed the torsional strength of all metal shafts of the same diameter. The typical failure location of all metal shafts is again in the weld area (heat affected zone). The welding process itself severely weakens the metal material properties of the adjacent metal tube. Any heat treatment of the metal is quickly undone due to the welding temperatures in the heat affected zone. Some of the shafts pictured above have an ultimate torsional strength of 6,000 ft. lbs.
We specialize in carbon fiber shafts! We are not a shaft fabricator that buys a generic carbon tube and glues yoke ends into it. We are an engineering driven composite design and manufacturing company. We have complete engineering, manufacturing, and testing capabilities to take any shaft design program from concept through verification testing and final production implementation. We manufacture our carbon fiber shafts in-house from the raw carbon fiber to the finished assembly. Our joint design is a unique/proprietary combination of geometry, material selection and manufacturing process methods. This has resulted in a structure that has had zero field failures over a wide variety of shaft types and over multiple years of production. We use the highest strength, most expensive carbon fiber strands available in all of our engineered shaft designs. The fiber we use is 33% stronger than typical, commonly-used carbon fiber. We also use the highest strength, most expensive aluminum alloy in our flanges. We do not machine our flanges from 6061-T6, which is a lower strength alloy. All of our engineered shafts are designed and fabricated from the ground up. The final result is the lightest, strongest and highest RPM capability shafts. In many cases, our final shaft weights are multiple pounds lighter than the shafts of our competition. In other words, just because it is a carbon fiber shaft doesn't mean it is better or lighter than a metal shaft.
BAC successfully designed and manufactured the propshaft used in the first flying car by Terrafugia. The Transition®, a street-legal airplane that converts between flying and driving modes in under a minute.
BAC also designed and manufactured the composite tail shaft for the Sikorsky Dragon Warrior UAV. The tail shaft is 1.25" O.D., 36" long and operates at 10,000 RPMs.