Payloads such as satellites or spacecraft, which are mounted on launch vehicles, are subject to severe vibrations during flight. These vibrations are induced by multiple sources that occur between liftoff and the instant of final separation from the launch vehicle. A direct result of severe vibrations is that sensitive payload components may experience fatigue damage and failure. For this reason, ATA designed a unique payload adapter with special emphasis on its vibration isolation characteristics.

In Phase I of a Small Business Innovation Research program (SBIR) the design concept feasibility was analytically assessed. In Phase 2, full-scale prototype multiple payload adapter hardware was fabricated and successfully tested to design limit load levels. In addition, modal test results showed the adapter axial and bounce frequencies to be in line with analysis predictions, indicating good isolation performance.

In conjunction with the Air Force Research Laboratory (AFRL), ATA developed a generic payload adapter using materials, mechanical design, and manufacturing methods to minimize the cost while meeting specific design requirements. These include isolation above a specified frequency, capability for multiple payload manifests, and integrated damping. The payload adapter is designed for an ICBM-derived launch vehicle using decommissioned Peacekeeper (PK) missiles; however, expandability for different launch systems is also a key project objective, and the design concept can be adapted to different launch vehicles. Further, the adapter offers the ability to launch multiple payloads to meet "ride-sharing" requirements.

ATA developed the following modular design to meet rigid program requirements:

• The payload adapter was tuned to achieve the desired isolation frequency and included constrained layer damping to further improve its dynamic performance.
• The secondary adapter is used in conjunction with the payload adapter to enable multiple payload manifests.

The design consists of an annular 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 (45Hz-200Hz). A 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. ATA's payload adapater design has been tested to higher loads than it would experience in service.

For more information about ATA's payload adapter, please contact us.

Related Technical Papers

Thomas, G.R., C.M. Fadick, and B.J. Fram, Launch Vehicle Payload Adapter Design with Vibration Isolation Features, 12th Annual SPIE International Symposium on Smart Structures and Materials, San Diego, California, Mar 6-10, 2005.

Fram, B.J., G.R. Thomas, and C.M. Fadick, A Multi-Payload Adapter for Peacekeeper Based Launch Vehicles, Space 2004 Conference and Exhibit, San Diego, California, 09, 2004.