To characterize a bipod of the new Isolator configuration, we performed a series of sine vibration tests  with a 18.1-kg (40-lb) mass attached at 0.25 g, 2.5 g’s, 7.5 g’, 12 g’s, and 16.25 g’s from 5 Hz to 1 kHz;  we performed a random vibration test from 10 Hz to 2000 Hz at a level of 9.1 Grms the results of which  will not be discussed here be cause of the similarity to the sine test results; we also performed a 900 G-  SRS Shock Beam test with a 18.1-kg (40-lb) payload mass and a 31.8-kg (70-lb) payload mass. These  tests characterized the isolator and showed how the “Q” (amplification factor) at the isolator resonant  frequency compared at the different input “g” levels. The testing also found that the lateral mode of the  isolator was very well damped and that there was an undamped machined spring surge mode at 61 5 Hz.  All the testing was performed in the Honeywell Vibration Lab.  This paper will describe the development of the new isolator D-strut@ for the Laser Communication  Terminal and the testing performed on the development bipod.  Design Requirements and Analysis  The design requirements for the D-strut@ are not finalized at this stage of the program. However, there are  some preliminary design requirements that are design drivers for the sizing of the D-strut@ isolator for the  instrument. The original desire was to use an existing D-strut@ isolator’ design that Honeywell had  qualified for launch and on-orbit isolation for another application. See Reference 1 for detailed description  of the existing qualified D-strut@ isolator design. The original qualified system had been developed for a  smaller payload, lower environmental loads, and the system isolation requirements were less stringent. A  comparison of the requirements for the previous system and the new system is shown in Table 1. The  impact of these design requirements differences and how they affect the design will be discussed in the  following paragraphs.  Table 1. Design Requirements Comparison  ImDact of Requirements on the new D-Strut@ Isolator Desian  The peak damping force requirement was one of the limiting factors in the previous D-strut@ isolator  design. The existing design would have to be redesigned to meet the new design requirements. The new  design is a through shaft system with externally pressurized sealing bellows. By externally pressurizing  the sealing bellows, there is no squirm pressure limitation. The externally pressurized bellows design is  stable, Le., increasing the pressure does not cause the bellows to try to move to one side since the fluid is  always pushing in. The limitation of the externally pressurized bellows is the strength of the bellows  materials resisting the pressure and external loads. Because of this difference in the design, the new  design capabilities exceed 87.02 kPa (600 psi) which is a factor of 2 over the previous qualified isolator  design.  Another limiting factor in the existing qualified D-strut@ isolator design is that the dynamic stroke of k5.1  mm (0.20 inch) will not meet the new requirement of k 8.13 mm (k 0.32 in). The new D-strut@ isolator  design contains externally pressurized bellows and does not have the limiting pressure issue; therefore,  the bellows stroke capabilities can be increased by adding more convolutes and increasing the bellows  1 42