Mass fluctuations that arise from Mach effects when objects that can store internal energy are accelerated and their application to the production of propellantless thrusts are briefly reviewed. Follow-on experimental work to that reported at STAIF 2004, 2005, and 2006 is described. In particular, thrusts in "flux capacitors" made with high voltage disk capacitors wound with coils that produce a magnetic flux therein were sought. An effect of the sort expected continues to be observed. And it displays scaling behavior distinctive to the presence of Mach effects. Various tests for the genuineness of the observed thrusts are described and discussed. The observed effect suggests that the objective of this work, useful propellantless propulsion, may be achievable. And if Mach effects do indeed exist, then generation of significant quantities of "exotic" [negative mass] matter may be possible making the generation of traversable wormholes feasible.