The analytical ultracentrifuge for the Open AUC Project is simply a rotating sample holder that sits in three optical paths simultaneously. Sketches are shown of the CFA (A, B) and fiber composite eight hole rotor (C) being developed for the Open AUC Project by Spin Analytical. The base centrifuge (A, B) simply consists of a vacuum containment chamber (a), a rotor (b), and high-speed motor (c). Since only analytical rotors will be used in this instrument, a shorter rotor chamber may be used. Three optical tracks are arranged at 120° intervals around the chamber. The optical tracks (B) have to use a periscope to avoid the drive motor. While complicating the optical path somewhat, using the periscopes means that the CFA can accommodate different drive motors, thus providing flexibility for future designs. The new rotor (C) being developed by Spin Analytical holds eight samples and may be operated at speeds up to 60,000 rpm. The sample holders are compatible with existing cell components