A CubeSat-scale telescope with a membrane primary optic was selected as an example threedimensional deployment application to demonstrate the flexible composite technology. The primary objective of this effort was to design the tape springs and determine the required mechanisms to develop a kinematic functional unit. There are many features required for an operational CubeSat payload not designed in detail, such as a primary deployment stage that would be required to translate the telescopefrom the bus interior such that the extendable booms do not impinge the CubeSat walls. These features were a factor in the design of the deployment mechanism and fixtures of the prototype unit, such that there is a feasible transition from the prototype to a flight system. This is the first known documentation of the fabrication and demonstration of this specific class of a three-dimensional deployable structure featuring flexible composite mechanisms. Two papers [6,7] regarding this structure were previously  published and presented that primarily focused on the overall structure and membrane design for the deployable membrane telescope. This paper describes in detail the designs of the mechanisms required  to enable successful operation of the structure and aims to serve as a design guide for integrating flexible composite components in existing or conceptual deployable structure architectures. The detail mechanical design of the mechanism is first described. An overview of flexible composite research is then presented along with the tape spring laminate and geometry design. Results of the functional deployment tests are discussed next, followed by the lessons learned from this effort. Mechanism Design Design Summary The telescope design in the deployed and stowed configurations is illustrated in Figure 1. The deployable  structure subsystem consists of a planar tri-member frame (“top frame”) that is extended from the base  mechanism by three deployable booms. Three pull points to tension the membrane was selected  because this represents the minimum number to uniquely define a plane. Introducing additional pull  points creates an over-determined set that will introduce out-of-plane deformations in the membrane if all  points are not precisely located on the nominal plane. The positions of the membrane pull points are  controlled by high-stiffness bipedal lanyards at each corner location. The membrane corner pull points are  attached to the deployable support structure by high-compliance decoupling spring. Membrane tension is  then set by the deployed structure dimensions. A decoupling spring with relatively high compliance reduces the tension sensitivity to the structure dimensional stability. The support structure in this effort  was designed to deploy and position a 20-cm-diameter optic with an f-number of 2, and stow within 1U  (10 cm x 10 cm x 10 cm) CubeSat volume. The associated compaction ratio to achieve this objective is traceable to the requirements of desired larger diameter applications. The assembled system stows into a volume of 9.4 cm x 9.4 cm x 8.3 cm tall with an assembled mass of 133 g. All tape spring members had a semi-circular cross section and radius of 5.56 mm.  Tape Spring Hub Mechanism The deployed structure shown in Figure 1 is fully determinant when using only pin-type joints at the tape  spring ends. This allows elimination of any latching mechanism for each tape spring at full deployment. The hub mechanism is a simple bearing-supported shaft free to rotate. Exploded and assembled renderings of the top frame hub corner assembly are shown in Figure 2. The tape spring hub assembly is identical for the top frame members and the booms mounted to the base plate. The only difference is in the design of the hub assembly mounting fixture. The central hub disk is fabricated from two pieces that clamp the tape spring end. Hub disk and tape spring components are aligned using two dowel pins and the assembly is bonded with adhesive. The hub disk controls the tape spring roll diameter in the stowed  state and mates with the hub shafts, which are concentric with the hub disc. Thickness of the hub disk  was kept to a minimum to keep the rotary inertia low during deployment. The geometry and laminate of the FRP composite tape spring are designed such that no containment devices are required to maintain a tight roll of the tape spring around the central hub disk while stowed or during the deployment process. Circumferential and side containment shrouds (circumferential shrouds not shown in Figure 2 for clarity)  are included to prevent anomalous deployment events. The side shrouds are circular disks that mounted  to the hub shafts and rotate with the tape spring roll. This basic shroud design was first implemented in  498