A Multi-payload Adapter for Peacekeeper-based Space Launch Vehicles

Abstract

A key enabler of many future DoD Space Test Program (STP) missions is a low cost, reliable launch vehicle with the capability to place multiple payloads, of moderate mass, into orbit. The Peacekeeper Space Launch Vehicle (PKSLV), being developed by the Rocket Systems Launch Program (RSLP) of the Space and Missile Systems Center (SMC), utilizes decommissioned Peacekeeper ICBM assets to economically place payloads into orbit. Depending on configuration and launch site, the PKSLV can place up to 1590 Kg into Low Earth Orbit (LEO). Growth versions of the PKSLV may be able to launch up to 3500 Kg. To get maximum usefulness and economy out of this launch capability, multiple payloads will often need to be launched on a PKSLV. One potential drawback to the PKSLV is the severity of the launch environment experienced by the payload(s). Therefore, any sensitive payloads that fly on the PKSLV will likely require some form of vibration isolation and shock damping system. Under a Phase II Small Business Innovative Research contract, with the Air Force Research Laboratory – Space Vehicles Directorate, ATA Engineering is developing a Multi-Payload Adapter (MPA) for the PKSLV. ATA’s MPA, on current versions of the PKSLV, will be able to support a typical manifest comprising of a primary payload of approximately 1,000 lbs and four secondary payloads of up to 200 lbs. The MPA design consists of an annular flat plate that has top and bottom face sheets separated by radial ribs and close-out rings. These components are manufactured from graphite epoxy composites to ensure a high stiffness to weight ratio. The design is tuned to keep the frequency of the axial mode of vibration of the payload on the flexibility of the adapter to a low value. This is the main strategy adopted for isolating the payload from damaging vibrations in the intermediate to higher frequency range. The design challenge for this type of adapter is to keep the pitch frequency of the payload above a critical value in order to avoid dynamic interactions with the launch vehicle control system. This high frequency requirement conflicts with the low axial mode frequency requirement and this problem is overcome by innovative tuning of the directional stiffnesses of the composite parts. A second design strategy that is utilized to achieve good isolation characteristics is the use of constrained layer damping. This feature is effective at keeping the responses to a minimum, in particular for the resonant burn condition present in any stage powered by a solid rocket motor. ATA is currently entering the detailed design phase of the MPA development. By early 2005 ATA will have prototype flight hardware manufactured for the PKSLV MPA. At that time, qualification testing to confirm the MPA’s structural performance will commence. A potential first flight for the MPA is in the 2006-2007 time-frame.