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This paper presents the test results and data correlation for the Heat Pipe Performance Flight Experiment which was a Class D middeck experiment flown aboard the Space Shuttle Columbia (STS-52) in October of 1992. Three categories of heat pipe performance were examined: static mode, operation under applied acceleration, and re-wicking capability. Two aluminum/freon axially grooved heat pipes, ten copper/water axially grooved heat pipes, and four fibrous wick copper/water variable conductance heat pipes were tested. Ground and flight test results for the axially grooved heat pipes are discussed and correlated with analytical models. Correlation of flight test data for cryogenic axially grooved oxygen heat pipes and a description of the Groove Analysis Program (GAP) is also presented.

This paper summarizes flight test results which were obtained in the Cryogenic Two Phase Flight Experiment (CRYOTP). This was a HitchHiker canister experiment that was flown aboard the space shuttle Columbia in March of 1994. Two flight articles were tested independently. The first was a nitrogen heat pipe with five parallel fibrous copper cable wicks. It did not startup in either of two cooldown cycles. Post flight inspection of the heat pipe showed that it had its original fluid charge. The failure to startup is attributed to the large fluid inventory and the conduction gradient that existed due to nominal parasitic heat leaks along the titanium heat pipe tube. Complete success was obtained with the Brilliant Eyes Thermal Storage Unit (BETSU) which contains 2-methylpentane phase change material for temperature control at 120K. More than 200 hours of on orbit tests consisting of several cooldown cycles and 55 freeze/thaw cycles was obtained with BETSU.