Conventional rockets all use a traditional bell nozzle. The nozzle represents lost weight from a payload point of view, but is necessary to direct thrust and ensure that the exhaust gas expands at the correct rate. However, this expansion velocity is dependent on the external air pressure, and for a rocket, that pressure is constantly changing. In other words, traditional bell nozzles are a compromise; while they are effective at optimizing thrust for a given external air pressure, they are less efficient at other points during the rocket's trajectory. Nozzle design traditionally involves selecting an external pressure to design to; in every other part of the trajectory, the rocket will be under or over expanded. The objective of this proposal is to obtain experimental flight data to validate a plug cluster aerospike design. In phase 1 of this proposal we will design and manufacture the thrust mount for the plug-cluster aerospike assembly. This will provide the thrust and other telemetry data for sea-level pressure conditions. In future phases we will collect suborbital flight data, utilizing a suborbital flight of the Firefly Alpha launch vehicle first stage, in addition to ground testing.