Editing Project Mercury (section)

===Suborbital flight===
{{Multiple image |total_width=365px
|image1=Chimpanzee Ham in Biopack Couch - cropped.jpg|caption=
|image2=Mercury-Atlas 5 Enos with handler (cropped).jpg |caption2=
|footer=Space pioneers [[Ham (chimpanzee)|Ham]] (left), who became the first [[great ape]] in space during his [[Mercury-Redstone 2|January 31, 1961, mission]], and [[Enos (chimpanzee)|Enos]], the only chimpanzee and third primate to orbit the Earth ([[Mercury-Atlas 5|November 29, 1961]]), were research subjects in the Project Mercury program.}}
The [[Mercury-Redstone Launch Vehicle]] was an {{convert|83|ft|m|adj=mid|-tall}} (with capsule and escape system) single-stage launch vehicle used for suborbital ([[ballistic missile|ballistic]]) flights.{{sfn|Catchpole|2001|p=206}} It had a liquid-fueled engine that burned alcohol and liquid oxygen producing about {{convert|75,000|lbf|kN}} of thrust, which was not enough for orbital missions.{{sfn|Catchpole|2001|p=206}} It was a descendant of the German [[V-2 (rocket)|V-2]],{{sfn|Alexander & al.|1966|p=21}} and developed for the [[U.S. Army]] during the early 1950s. It was modified for Project Mercury by removing the warhead and adding a collar for supporting the spacecraft together with material for damping vibrations during launch.{{sfn|Catchpole|2001|p=207}} Its rocket motor was produced by [[North American Aviation]] and its direction could be altered during flight by its fins. They worked in two ways: by directing the air around them, or by directing the thrust by their inner parts (or both at the same time).{{sfn|Alexander & al.|1966|p=21}} Both the Atlas-D and Redstone launch vehicles contained an automatic abort sensing system which allowed them to abort a launch by firing the launch escape system if something went wrong.{{sfn|Catchpole|2001|pp=209, 214}} The [[Mercury-Jupiter|Jupiter]] rocket, also developed by [[Wernher von Braun]]'s team at the Redstone Arsenal in Huntsville, was considered as well for intermediate Mercury suborbital flights at a higher speed and altitude than Redstone, but this plan was dropped when it turned out that man-rating Jupiter for the Mercury program would actually cost more than flying an Atlas due to economics of scale.{{sfn|Alexander & al.|1966|p=151}}{{sfn|Grimwood|1963|p=69}} Jupiter's only use other than as a missile system was for the short-lived [[Juno II]] launch vehicle, and keeping a full staff of technical personnel around solely to fly a few Mercury capsules would result in excessively high costs.{{citation needed|date=January 2017}}