View source for Stratobowl

{{Short description|Compact natural depression}}
{{coord|43.97668|-103.3452|display=title}}
[[File:Explorer II Gondola.jpg|thumb|upright|[[Explorer II]] gondola in the [[National Air and Space Museum]]]]

The '''Stratobowl''' is a compact natural [[Depression (geology)|depression]] within the limits of [[Black Hills National Forest]] in [[South Dakota]], south-west of [[Rapid City, South Dakota|Rapid City]]. In 1934–1935 it housed a [[stratosphere|stratospheric]] [[balloon]] [[launch site]], initially known as '''Stratocamp''', sponsored by the [[National Geographic Society]] and the [[United States Army Air Corps]]. In 1956–1959 the site was reused by the U.S Navy [[Project Strato-Lab]].

==''Explorer'' balloons==
In 1934 the NGS and Air Corps co-sponsored the ''Explorer'', a [[observation balloons|manned]] [[high-altitude balloon]] capable of stratospheric flight. After the crash of the Soviet ''[[Osoaviakhim-1]]'' that nevertheless set an altitude record of {{convert|72178|ft|m}}, the sponsors redefined their primary objectives from record-setting to scientific research and tests of new navigation instruments.<ref name=R52/> Air Corps Capt. [[Albert William Stevens]], Capt. [[Orvil Arson Anderson]] and Maj. [[William Ellsworth Kepner|William E. Kepner]] were selected to fly the ''Explorer''.<ref name=R52>Ryan, p. 52</ref> Kepner and Anderson, experienced balloonists, were in charge of locating a suitable launch site. According to Kepner, an ideal site would be a [[crater (disambiguation)|crater]] or [[canyon]], a clear grassy valley encircled with rocky ridges high enough to shield the tall balloon from any wind.<ref>For the same reasons, the U.S. Navy's later Stratolab project used old mining pits near [[Crosby, Minnesota]] – Ryan, p. 229</ref> Ideally, the launch site it would have a high-voltage electric line, road and rail access, "and a [[trout]] stream".<ref name=R53/> Kepner and Anderson eventually located their dream canyon near [[Rapid City, South Dakota]]. City officials, fascinated by the expected publicity campaign, agreed to build a road and electric line.<ref name=R53>Ryan, p. 53</ref>

Anderson directed construction of a temporary village, housing over 100 people, with the help of the [[South Dakota National Guard]] and the army's [[4th Cavalry Regiment (United States)|4th Cavalry Regiment]].<ref name=R53/> The central pad, {{convert|200|ft}} in diameter, was cushioned with sawdust to protect the fabric of the balloon as it was spread on the ground prior to inflation. Preparation for flight was regularly reported by the national press. ''Explorer'' lifted off at 6:45, July 28, 1934, an event broadcast live over the radio and watched by 30,000 spectators on site.<ref name=R54/> After seven hours in flight<ref name=S22/> the pilots noticed holes torn in the bottom of the gas bag; quickly losing gas, the balloon plunged into an uncontrolled dive, its gas bag disintegrating as the balloon picked up vertical speed.<ref name=R54>Ryan, p. 54</ref> At {{convert|5000|ft}} the remaining hydrogen exploded, sending the gondola in a free fall. According to Ryan, the pilots managed to bail out ''after'' the explosion, Kepner at an altitude of barely {{convert|500|ft}};<ref name=R55/> according to Shayler, they bailed out before the explosion; all three survived uninjured.<ref name=S22/> Later it turned out that the ''Explorer'' missed a world record by {{convert |624|ft}}.<ref name=R55>Ryan, p. 55</ref> The accident was linked to folds in the balloon's fabric that put it under extreme stress as the balloon expanded in stratosphere.<ref name=S22>Shayler, p. 22</ref>

The NGS and Air Corps vowed to launch a new balloon in June 1935,<ref name=R55/> but the new [[helium]]-filled ''[[Explorer II (balloon)|Explorer II]]'' was not ready until November.<ref name=R58>Ryan, p. 58</ref> Watched by 20,000 spectators,<ref name=R58/> ''Explorer II'' lifted off at 8:00 November 11 and reached a new record height of {{convert|72395|ft|m}}.<ref name=S20>Shayler, p. 20</ref> Anderson, Kepner, and Stevens became the first men to view the Earth's [[curvature]].<ref name=R589>Ryan, pp. 58–59</ref>

==''Strato-Lab balloons''==
In the 1950s, [[Project Manhigh]]<ref>Ryan. pp. 99–100</ref> and [[Project Strato-Lab]] launches were made from the man-made crater of an iron mining pit near [[Crosby, Minnesota]], and, if weather allowed, from Fleming Field in [[South St. Paul, Minnesota]].<ref>Ryan, p. 79</ref> The Stratobowl was a backup location. There was one Stratobowl launch in 1956, three in 1958, and seven in 1959. On November 8, 1956, the ''Strato-Lab I'' gondola lifted [[Malcolm Ross (balloonist)|Malcolm Ross]] and M. L. Lewis from the Stratobowl to a world altitude record for manned balloon flight of {{convert|76000|ft|m}}. The purpose of the flight was to gather meteorological, cosmic ray, and other scientific data necessary to improve safety at high altitudes.<ref>Ross and Lewis, 1957</ref> The most publicized flight, ''Strato-Lab IV'' piloted by Malcolm Ross and [[Charles B. Moore]], lifted off from Stratobowl on November 28, 1959, reached an altitude of {{convert|81000|ft|m}}, and landed safely in [[Kansas]] after 20 hours in the air. The purpose of the flight was to perform spectrographic analysis of the planet Venus with minimal interference from the Earth's atmosphere.<ref>Ryan, p. 233</ref>

==Notes and references==
{{reflist | colwidth= 30em }}

==Sources==
{{refbegin|indent=yes}}
* {{cite book | title=The Pre-Astronauts | author=Ryan, Craig | year=2003 | publisher=Naval Institute Press |isbn=978-1-59114-748-0| url=https://books.google.com/books?id=1QS38bu9iTwC }}
* {{cite web | url=http://photography.nationalgeographic.com/photography/photographers/high-altitude-photography.html | author=Lee Wells, Jr. | year=1935 | title=First High-Altitude Photo | publisher=[[National Geographic (magazine)|National Geographic]] | url-status=dead | archiveurl=https://web.archive.org/web/20100118145349/http://photography.nationalgeographic.com/photography/photographers/high-altitude-photography.html | archivedate=2010-01-18 }}
* {{citation | last1 = Ross | first1 = Malcolm D. | last2 = Lewis | first2 = M. Lee | title = To 76,000 Feet by ''Strato-Lab'' Balloon | journal = National Geographic Magazine | volume = 111 | issue = 2 | pages = 269–282 |date = February 1957 }}
* {{cite book | author=Shayler, David | url=https://books.google.com/books?id=ng9i5IMtlpsC&dq=Vasenko&pg=PA20 | title=Disasters and accidents in manned spaceflight | publisher=Springer | year=2000 |isbn=978-1-85233-225-9| pages=20–22 }}
{{refend}}

==External links==
* [http://stratocat.com.ar/bases/56e.htm History] from StratoCat.com.ar &mdash; The use of stratospheric balloons, the scientific research, the military field, and the aerospace activity

{{Black Hills, South Dakota}}

[[Category:Ballooning]]
[[Category:Black Hills National Forest]]
[[Category:Landforms of Pennington County, South Dakota]]
[[Category:1934 in South Dakota]]
[[Category:History of aviation]]