An experimental investigation was performed to determine the effect of transient body forces on the performance of an ammonia/aluminum axial groove heat pipe. The effects of increased body forces on the dryout and rewet performance were simulated by tilting the heat pipe to different inclination angles. Theoretical calculations predicted the dryout length varied with different final inclination angles. The steady state experimental work was performed by tilting the heat pipe from 0 degrees to different final inclination angles for a long period of time until totally dryout occurred. Then, from the plot of the changing temperature at each location along the heat pipe, the dryout length could be predicted. Under steady state condition, the percent error between the experimental and theoretical data differed by as low as 50%. The transient experimental work was performed by tilting the heat pipe from different initial inclination angles to different final inclination angles under three duration conditions. The time for the heat pipe to dryout, rewet, and return to the initial condition was observed as a function of the initial inclination angles, the final inclination angles, and duration of the heat pipe at the final angle. The results revealed that the larger body force (or the larger final inclination angle) increased the dryout length, and increased the time to return to its initial condition. The duration of the adverse angle had less of an effect on the time to rewet. But the initial inclination angle has a strong effect on the time to rewet. When the initial inclination angle was 0 degrees, it took around 3 to 6 seconds to rewet. When the initial inclination angle became 1 degrees, it took around 5 to 12 seconds to rewet. When the initial inclination angle was 1.25 degrees, it took around 15 to 17 seconds to rewet
