EmDrive is the name given to a new propellant-less propulsion technology which has its origins incold war missile research. The subsequent development work has been shrouded in secrecy and publiccontroversy, and has therefore been largely overlooked by the wider propulsion community. With thetechnology now maturing, it is time for EmDrive to come out of the shadows. This paper examines oneaspect of EmDrive which has caused many experimental problems. The search for thrust from a varietyof EmDrive type thrusters, operating at safe, low microwave power levels, has led to very sensitive thrustmeasurements being attempted. These experiments mainly use torsional balances. In practice this hasinevitably led to no thrust being measured. The problem is that, unlike a rocket, but more like an electricalmachine, EmDrive requires to work against a load before thrust can be measured. The theory behindthis statement is given and a simple idealised experiment is described. The results for overload, optimumload and no load conditions are predicted. An experiment was set up using the original SPR FlightThruster, recovered after years of testing with two other research groups. The thruster was mountedon a counterbalanced beam with thrust and load measured on a precision electronic balance. A set ofexperimental results, originally revealed in a lecture given at The UK Defence Academy Shrivenham, arepresented. The experiment confirmed the predictions. This is not surprising, as the original radiationpressure theory behind the EmDrive concept is firmly based on classic physics, and complies with thelaws of conservation of momentum and energy. The implication of this result is that EmDrive will notnecessarily accelerate a spacecraft, when in a true free-space orbital environment, unless steps are takento introduce a load vector. It further illustrates that in-orbit tests, using a single EmDrive thruster, willgive anomalous results. However when EmDrive is applied to a direct flight to the Moon, where a gravityload vector is present, preliminary mission analysis gives very encouraging predictions. The results of asubsequent study of a manned Moon mission are presented.