Project HARP: Difference between revisions

'''Project HARP''', short for '''Highhigh Altitudealtitude Researchresearch Projectproject''', was a joint venture of the [[United States Department of Defense]] and [[Canada]]'s [[Department of National Defence (Canada)|Department of National Defence]] created with the goal of studying [[ballistics]] of [[re-entry vehicle]]s and collecting upper atmospheric data for research. Unlike conventional space launching methods that rely on rockets, HARP instead used very large guns to fire projectiles into the atmosphere at extremely high speeds.<ref name=":1">{{Cite journal |last1=Petrescu |first1=Relly |last2=Aversa |first2=Raffaella |last3=Akash |first3=Bilal |last4=Berto |first4=Filippo |last5=Apicella |first5=Antonio |last6=Petrescu |first6=Florian |date=2017 |title=Project HARP |journal=Journal of Aircraft and Spacecraft Technology |volume=1 |issue=4 |pages=249–257 |ssrn=3092679 |doi=10.3844/jastsp.2017.249.257 |doi-access=free }}{{predatory publisher}}</ref><ref name=":2">{{Cite newsmagazine |last=Hanson |first=Joe |url=https://www.wired.com/2013/07/science-goes-ballistic-8-guns-for-hunting-knowledge/ |title=Science Goes Ballistic: 8 Guns for Hunting Knowledge |date=July 8, 2013 |workmagazine=Wired |access-date=February 11, 2020 }}</ref>

A {{convert|16-inch|in|cm|adj=on}} HARP gun operated by the U.S. Army's [[Ballistic Research Laboratory]] (now called the [[United States Army Research Laboratory|U.S. Army Research Laboratory]]) at [[Yuma Proving Ground]] currently holds the world record for the highest altitude (180&nbsp;km)that a gun-fired projectile has achieved: {{convert|180|km|mi|1}}.<ref name=":3">{{Cite web |url=http://www.astronautix.com/a/abriefhistoheharpproject.html |archive-url=https://web.archive.org/web/20160820020119/http://www.astronautix.com/a/abriefhistoheharpproject.html |url-status=dead |archive-date=August 20, 2016 |title=A Brief History of the HARP Project |last=Graf |first=Richard |website=Encyclopedia Astronautica |access-date=February 11, 2020}}</ref><ref name=":5">{{Cite news |last=Sterling |first=Bruce |url=https://www-istp.gsfc.nasa.gov/stargaze/SGbull.htm |title=Think of the Prestige |date=September 1992 |work=The Magazine of Fantasy and Science Fiction |access-date=February 11, 2020 }}</ref>

Project HARP originated as the brainchild of [[Gerald Bull]], a renowned but controversial ballistic engineer specializing in high-velocity guns and gun propulsion systems.<ref name=":2" /><ref name=":3" /> In the mid-1950s, Bull was working on [[Anti-ballistic missile|Antianti-Ballisticballistic Missilemissile (ABM)]] and [[Intercontinental ballistic missile|Intercontinentalintercontinental Ballisticballistic Missilemissile (ICBM)]] research at the [[DRDC Valcartier|Canadian Armaments and Research Development Establishment (CARDE)]] when he formulated the idea to launch [[satellite]]s into orbit using an enormous cannon.<ref name=":1" /><ref name=":3" /> Bull believed that a large supergun would be significantly more cost-effective at sending objects into space than a conventional rocket. Bull argued it would not need expensive rocket motors, firing a large gun wouldn't require the missile to throw away multiple [[Multistage rocket|rocket stages]] to break through the Earth's atmosphere to reach orbit.<ref>{{Cite news|last=Park|first=William|url=https://www.bbc.com/future/article/20160317-the-man-who-tried-to-make-a-supergun-for-saddam-hussein|title=The tragic tale of Saddam Hussein's 'supergun'|date=March 17, 2016|work=BBC|access-date=February 11, 2020}}</ref> In theory, a [[Sabot (firearms)|sabot]] would protect the payload during firing and later fall away as the satellite inside emerges.<ref name=":6">{{Cite news|last=Grundhauser|first=Eric|url=https://www.atlasobscura.com/places/project-harp-space-gun-barbados|title=Project HARP Space Gun|date=May 2017|work=Atlas Obscura|access-date=February 11, 2020}}</ref>

During the late 1950s, Bull conducted preliminary launch experiments at the CARDE (now known as [[DRDC Valcartier|Defence Research and Development Canada – Valcartier]], or [[DRDC Valcartier]]) using guns as small as 76mm. These experiments soon caught the attention of the U.S. Army's Ballistic Research Laboratory and the U.S. Army's Chief of Army Research and Development, [[Arthur Trudeau|Lieutenant general Arthur Trudeau]].<ref name=":4">{{Cite web|url=http://www.friends-partners.org/mwade/lvs/5inrpgun.htm|title=5 inch HARP Gun|last=Graf|first=Richard|date=October 31, 2001|website=Encyclopedia Astronautica|access-date=February 11, 2020|archive-date=May 30, 2019|archive-url=https://web.archive.org/web/20190530235720/http://www.friends-partners.org/mwade/lvs/5inrpgun.htm|url-status=dead}}</ref> At the time, aircraft engineers needed more information on the atmosphere's upper regions to design better jet planes. However, launching rockets into the air to collect data was generally considered costly and inefficient.<ref name=":1" /><ref name=":3" /> The U.S. military, in particular, was especially in need of a low-cost launch system that could cover altitudes that conventional aircraft and [[weather balloon]]s couldn't reach to support the development of new supersonic aircraft and missile systems. By late 1960, CARDE and the Ballistic Research Laboratory (BRL) conducted several feasibility studies surrounding small gun-launched probes' structural integrity.<ref name=":4" /> Around the same time, BRL developed a smooth-bore, 5-inch gun system at [[Aberdeen Proving Ground]] that successfully launched a probe to altitudes exceeding 220,000 feet.<ref name=":3" /><ref name=":7">{{Cite news|url=https://books.google.com/books?id=4T48x5ELy5UC&q=ballistic+research+laboratory+project+HARP&pg=RA4-PA5|title=Project HARP Leads to U.S.-Canada Study of Low-Orbit Program|date=May 1964|work=Army Research and Development|access-date=February 11, 2020|issue=5|volume=5|page=5}}</ref>

In 1961, Bull resigned from CARDE and [[McGill University]] hired him as a professor. Working together with Donald Mordell, the university's Dean of Engineering, Bull moved forward with his space gun project and requested funding from various sources. He received a $200,000 loan from McGill University's board of governors. He was given a verbal promise for a $500,000 grant from the Canadian Department of Defence Production (CDDP), which was later reportedly denied due to bureaucratic opposition.<ref name=":1" /><ref name=":3" /><ref name=":8">{{Cite journal|last=Lukasiewicz|first=Julius|date=April 1986|title=Canada's Encounter with High-Speed Aeronautics|journal=Technology and Culture|volume=27|issue=2|pages=223–261|doi=10.2307/3105144|jstor=3105144|s2cid=111725650 }}</ref> In October 1961, Bull met with Charles Murphy, the head of the Ballistic Research Laboratory, to pitch his project for a supergun and was met with overwhelming support. The U.S. Army provided Bull with substantial financial backing and two 16-inch naval [[gun barrel]]s complete with a land mount and surplus powder charges, a heavy-duty crane, and a $750,000 radar tracking system.<ref name=":3" /><ref name=":5" /><ref name=":7" /> Bull and Mordell officially announced the HARP project as a program under McGill University's Space Research Institute at a press conference in March 1962.<ref name=":3" /> HARP was presented as a research initiative dedicated to "developing low-orbital capacity for [[Geodesy|geodetic]] and atmospheric objectives".<ref name=":7" /> However, the project's long-term goal was to place satellites into orbit<ref>{{Cite news|last=Trevithick|first=Joseph|url=https://www.thedrive.com/the-war-zone/19847/the-army-now-wants-hypersonic-cannons-loitering-missiles-and-a-massive-supergun|title=The Army Now Wants Hypersonic Cannons, Loitering Missiles, And A Massive Supergun|date=April 3, 2018|work=The Drive|access-date=February 11, 2020}}</ref><ref>{{Cite news|last=Oberholtzer|first=William|url=https://www.nationaldefensemagazine.org/articles/2012/2/29/2012march-an-inexpensive-solution-for-quickly-launching-military-satellites-into-space|title=An Inexpensive Solution for Quickly Launching Military Satellites Into Space|date=March 1, 2012|work=National Defense|access-date=February 11, 2020}}</ref> economically.

In 1962, Bull and Mordell established a McGill University research station on [[Barbados]] Caribbean island (then still a British colony and part of the [[West Indies Federation]]) as HARP's main base of operations for its 16-inch super gun.<ref name=":3" /><ref name=":9">{{Cite web|url=https://weathermodificationhistory.com/project-high-altitude-research-program-harp-cannons-launch-chemical-payloads-space/|title=Project High Altitude Research Program (HARP) Cannons Launch Chemical Payloads Into Space|date=June 1965|website=Weather Modification History|access-date=February 11, 2020}}</ref> The site location was first suggested by Mordell, who believed that a launch site closer to the [[equator]] would allow the projectile to procure extra velocity from the earthEarth's rotation to reach higher altitudes. In addition, the site's close proximity to the Atlantic Ocean made for the safe impact of re-entry projectiles.<ref name=":1" /><ref name=":3" /> As a result of McGill University's close connections with the island's [[Democratic Labour Party (Barbados)|Democratic Labour Party]], Bull met with the Barbados Prime Minister [[Errol Barrow]] to arrange the construction of a firing site at [[Foul Bay, Barbados|Foul Bay]], St. Philip.<ref name=":10">{{Cite web|url=https://www.barbadospocketguide.com/our-island-barbados/military/harp-gun.html|title=High Altitude Research Project (HARP Gun)|website=Barbados Pocket Guide|access-date=February 11, 2020}}</ref><ref name=":11">{{Cite book|last=Bull|first=Gerald|title=Paris Kanonen - The Paris Guns (Wilhelmgeschütze) and Project HARP (Wehrtechnik und Wissenschaftliche Waffenkunde)|publisher=E. S. Mittler & Sohn|date=May 1, 1991|isbn=978-3813203042|location=Hamburg, Germany|pages=144–234}}</ref> HARP reportedly received enthusiastic support from the Barbados government due to expectations that the island nation would become heavily involved in space exploration research.<ref name=":5" /><ref name=":9" />

The installation of the 16-inch gun began at the newly established High Altitude Research Facility onin April 1962. A gun pit was dug into the island's coral base, and a concrete emplacement was built on a plateau so that the gun barrel could stand vertically. The 16-inch naval gun barrels provided by the U.S. Army served as the barrels of the HARP gun. They had to be transported to the site on the U.S. Army landing ship, the [[John U. D. Page#Ships|Lieutenant Colonel John D. Page]], with the [[Transportation Corps|U.S. Army Transportation Corps]] assistance, the [[U.S. Army Research Office]], and the Office of the Chief of Research and Development.<ref name=":3" /><ref name=":9" /><ref>{{Cite journal|last1=Murphy|first1=Charles|last2=Bull|first2=Gerald|date=1968|title=Gun-launched probes over Barbados|journal=Bulletin of the American Meteorological Society|volume=49|issue=6|pages=640–644|doi=10.1175/1520-0477-49.6.640|bibcode=1968BAMS...49..640M|doi-access=free}}</ref> Hundreds of people from Barbados were employed to transport the two 140-ton gun tubes from the coast to the designated emplacement 2{{frac|1|2}} miles from the beach using a temporary purpose-built railway.<ref name=":9" /><ref name=":10" /> By late 1962, the HARP 16-inch gun was set up, and construction on workshops, storage buildings, radar installations, and other facilities neared completion.<ref name=":3" /> Around this time, the U.S. Army Research Office increased its financial support of the project to $250,000 per year.<ref name=":11" /> The first test shot from the 16-inch gun on Barbados was fired on January 20, 1963, marking the first time that a gun of this caliber was fired at a near-vertical angle. The 315&nbsp;kg test slug reached an altitude of 3000 meters inwith a flight time of about 58 seconds withat a launch velocity of 1,000&nbsp;m/s before coming down a kilometer off-shore.<ref name=":3" />

The projectiles fired by the 16-inch HARP gun on Barbados belonged to a family of cylindrical, finned missiles called Martlets, named after the [[Martin (bird)|martin bird]] that appeared on the McGill University crest.<ref name=":12">{{Cite web|url=https://www.daviddarling.info/encyclopedia/H/HARP.html|title=HARP (High Altitude Research Project)|website=David Darling|access-date=February 11, 2020}}</ref><ref name=":13">{{Cite web|url=https://apgdiscovery.com/stories-from-apg/now-thats-a-big-gun/|title=Now that's a big gun!|last=Deutsch|first=Elliot|website=APG Discovery Center|access-date=February 11, 2020}}</ref> Inside the gun barrel, the Martlet was surrounded by a sabot. This machined wooden casing protected the projectile as it traveled through the barrel by absorbing the combustive energy and then splitting apart in the air asafter the Martlet acceleratedexited upwardthe barrel. The Martlets also carried payloads of metallic chaff, chemical smoke, or meteorological balloons to gather atmospheric data as well as telemetry antennas for tracking the missile's flight.<ref name=":5" /><ref name=":13" /> The [[Harry Diamond Laboratories]]<ref>{{Cite journal|last=Finger|first=Daniel|title=Telemetry for 250,000-G Gun Environment|url=https://repository.arizona.edu/bitstream/handle/10150/578489/ITC_1965_65-14-3.pdf?sequence=1&isAllowed=y|format=PDF|journal=International Telemetering Conference Proceedings|via=The University of Arizona University Libraries}}</ref> designed several telemetry systems used in the HARP program. The firing of these Martlet missiles was always accompanied by a huge explosion that shook the houses within close proximity, leading to cracks in several areas. Since the Barbados government refused to recognize householders' damage claims, HARP fell into ill favor by much of the Barbados population.<ref name=":10" /><ref name=":12" />

In 1964, the HARP gun on Barbados continued to primarily launch Martlet 2 missiles that carried a wide variety of payloads. Part of the reason was its low cost, since the firing of the Martlet 2 cost from $2500 to $3000 and took only half an hour to load.<ref name=":3" /><ref>{{Cite web|url=https://yarchive.net/space/project_harp.html|title=Re: Cannon Launch? (Very cheap access to space)|last=Dunn|first=Bruce|date=July 26, 1996|website=Usenet Archives|access-date=February 11, 2020}}</ref> The new results from HARP convinced the U.S. Army to increase the annual funding of the project from $250,000 to $1.5 million per year. By March 1964, Canada's Department of Defence Production (DDP) agreed to provide joint funding for the HARP program for a total of $3 million per year.<ref name=":3" /><ref name=":8" /><ref name=":11" /> However, HARP funding reportedly faced several obstacles in the form of bureaucratic sabotage due to opposition in the Canadian government.<ref name=":3" /> The funding promised by the DDP for July 1, 1964, to June 30, 1965, did not arrive until May 1965. During this period, McGill University covered the funds to the best of its ability, although changes had to be made to the original plan. For each subsequent funding periods, the DDP repeatedly delayed HARP funding late into the fiscal year.<ref name=":11" />

The first attempts to improve the performance of the 16-inch gun at Barbados were made in 1964, primarily by increasing the barrel's length.<ref name=":3" /> In 1962, the Ballistic Research Laboratory increased the barrel length of a 5-inch gun system by welding a second section of barrel to the first barrel's muzzle, lengthening the barrel to 8.9 meters. The resulting gun system demonstrated a higher muzzle velocity at the muzzle exit. The longer barrel allowed the propellant gases to push on the projectile for a longer period of time.<ref name=":3" /><ref name=":6" /><ref name=":14">{{cite report|url=https://www.governmentattic.org/3docs/3DugwayReports_1953-1966.pdf|title=Review of the High Altitude Research Program (HARP)|last1=Murphy|first1=Charles|last2=Bull|first2=Gerald|date=July 1966|publisher=Ballistic Research Laboratory|id=AD645284|via=Government Attic}}</ref> In September 1964, a ten-calibers extension was added to the 16-inch gun based on BRL's experiment with the 5-inch gun. However, while increased velocity and altitude was recorded for test flights, the extension failed in December after the eleventh shot was fired. In 1965, a successful extension of the 16-inch gun was established after enlarging the gun pit to accommodate the equipment's large size. The extension almost doubled the length of the gun to 120 feet and weighed nearly 100200 tons, making the 16-inch Barbados gun the largest operational artillery piece in the world at the time.<ref name=":3" /><ref name=":9" /><ref name=":12" /><ref>{{Cite news|url=http://www.slate.com/blogs/atlas_obscura/2013/07/03/project_harp_a_giant_space_gun_in_barbados_is_now_abandoned.html|title=Abandoned Space Gun Rusting Away in the Barbados Jungle|date=July 3, 2013|work=Slate|access-date=February 11, 2020}}</ref>

By the end of 1965, Project HARP had fired more than one hundred missiles at heights over 80&nbsp;km high into the [[ionosphere]].<ref name=":5" /><ref name=":12" /> At this point, the project starting planning the launch of the Martlet 4, a projectile that used rocket jets that would ignite mid-flight to send the missile into orbit.<ref name=":5" /> For this endeavor, BRL designed the telemetry system that utilized [[sunSun sensor]]s to determine the projectile's altitude. This telemetry system would serve as an early precursor to the U.S. Army's Aeroballistic Dynamic Fuze (DFuze).<ref>{{Cite journal|last1=Decker|first1=Ryan|last2=Yakimenko|first2=Oleg|last3=Hollis|first3=Michael|last4=Sweeney|first4=Patrick|date=May 2011|title=On the Development of the Artillery Flight Characterization Electronics Rescue Kit|url=https://calhoun.nps.edu/bitstream/handle/10945/45465/Decker_Artillery_Flight_Characterization.pdf?sequence=1|format=PDF|journal=Proceedings of the 21st AIAA Aerodynamic Decelerator Systems Technology Conference|pages=2|via=Calhoun: The NPS Institutional Archive}}</ref>

[[File:Abandoned-HARP-Gun.jpg|thumb|Abandoned HARP gun in Barbados]]Throughout 1966, the HARP program experienced a series of funding delays caused by immense opposition from critics in the Canadian government and growing bureaucratic pressures.<ref name=":3" /><ref name=":11" /> Upon the end of the Canadian government's participation in June 1967, the Canadian government had contributed $4.3 million and the US Army $3.7 million.<ref>{{cite web|url=http://artsites.uottawa.ca/sca/doc/Special-Study-No.-1-Upper-Atmosphere-and-Space-Programs-in-Canada.pdf|title=Upper Atmosphere and Space Programs in Canada - Special Study No 1 - February 1967|last=Forsyth|first=Chapman|date=February 11, 2020|website=uOttawa - Canadian Science Councils Archive|access-date=February 11, 2020|archive-date=June 13, 2020|archive-url=https://web.archive.org/web/20200613094730/http://artsites.uottawa.ca/sca/doc/Special-Study-No.-1-Upper-Atmosphere-and-Space-Programs-in-Canada.pdf|url-status=dead}}</ref>

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On the American side, growing political and financial pressure caused by the [[Vietnam War|Vietnam war]] and [[NASA]]'s focus on large-scale traditional rockets strained funding for the project as well, exacerbating the program's problems even further.<ref name=":2" /> In November 1966, the Canadian government announced that it would pull all Project HARP funding after June 30, 1967. Despite Bull's attempts to resuscitate the program, the Canadian government withdrew its support in 1967. This decision promptly caused the U.S. Army to withdraw its funding as well, leading to the program's complete termination. Both the HARP guns at Barbados and at Highwater Range were shut down, though the HARP guns under the jurisdiction of the U.S. military remained operational.<ref name=":3" /><ref name=":8" /> Project HARP's assets were transferred to Bull, who started a [[Space Research Corporation]] commercial operation to salvage his project.<ref name=":5" /> After HARP was cancelled, the 16-inch gun on Barbados remained on its emplacement, where it remains to this day, gradually rusting away.<ref name=":6" />

The guns used for Project HARP consisted of smooth-bore 5 inch, 7-inch, and 16-inch guns, all of which were designed to launch sub-caliber saboted projectiles into the upper atmosphere.<ref>{{cite report|url=https://apps.dtic.mil/dtic/tr/fulltext/u2/635782.pdf|archive-url=https://web.archive.org/web/20200609164020/https://apps.dtic.mil/dtic/tr/fulltext/u2/635782.pdf|url-status=dead|archive-date=June 9, 2020|title=The Development of a High Acceleration Testing Technique for the Electronic Instrumentation of HARP Projectile Systems|last1=Marks|first1=Spence|last2=Pilcher|first2=James|last3=Brandon|first3=Fred|date=March 1966|publisher=Ballistic Research Laboratory|id=AD635782|via=Defense Technical Information Center}}</ref> In addition to the High Altitude Research Laboratory at Barbados, a 16-inch HARP gun was constructed at the Highwater Range in Quebec and at Yuma Proving Ground in Arizona. Smooth-bore 5-inch and 7-inch guns were set up at several different test sites, including [[Fort Greely]], Alaska, [[Wallops Island]], Virginia, [[Aberdeen Proving Ground]], Maryland, and [[White Sands Missile Range]], New Mexico. The data collected from the projectiles fired from these gun systems were measured by radar chaff, aluminized balloons, [[Trimethylaluminium|trimethylaluminum]] trails, and sensors ranging from sun sensors to [[magnetometer]]s.<ref name=":14" />

The 5-inch HARP guns were based on a modified [[120 mm gun M1|120&nbsp;mm T123 service gun]] and used by the [[Ballistic Research Laboratory]] before the HARP program in order to fulfill the needs of the U.S. military's Meteorological Rocket Network, a program dedicated to collecting atmospheric wind and temperature data. They were designed to carry a 0.9&nbsp;kg payload to an altitude of 65&nbsp;km, which consisted of radar reflective chaff to collect wind data and small [[radiosonde]]s that returned radio telemetry of information like temperature and humidity as they drifted back down under large parachutes.<ref name=":4" /><ref name=":15">{{Cite journal|last=Kampe|first=H.J.|date=October 1960|title=Meteorological Rocket Network: For Measuring Atmospheric Parameters up to 250.000|journal=Weatherwise|volume=13|issue=5|pages=192–195|doi=10.1080/00431672.1960.9940979|bibcode=1960Weawi..13e.192K }}</ref> This initial design for the 5-inch HARP gun reached an altitude of 130,000&nbsp;ft when tested in 1961.<ref name=":14" /> The 5-inch L70 smoothbore guns was the first vertical firing gun system developed under Project HARP.<ref name=":11" /> In 1962, a 10-ft extension was implemented for the 5-inch HARP gun by welding a second barrel section to the first, allowing it to launch projectiles at muzzle velocities of 1554&nbsp;m/s (5,100&nbsp;ft/sec) to altitudes of 73,100&nbsp;m (240,000&nbsp;ft).<ref name=":14" /> Throughout HARP, further modifications were made to the 5-inch gun, such as adding three sets of stiffening wires to maintain barrel alignment. Due to their small size, they were easily transported from their initial site at Aberdeen Proving Ground to different launch sites across North America and the Caribbean.<ref name=":4" /><ref name=":15" /> One of the 5-inch HARP guns was acquired by the Atmospheric Sciences Laboratory (which consolidated into the U.S. Army Research Laboratory in 1992) to measure the stratosphere's winds.<ref>{{Cite news|last=Kennedy|first=Bruce|url=http://www.wsmr-history.org/HandsAcrossHistory-02-15.pdf|title=Gun Probe Was Used To Study Winds|date=February 2015|work=Hands Across History|access-date=February 11, 2020}}</ref> The 5-inch gun was deemed successful as a low-cost launch system, costing only around $300 to $500 per launch.<ref name=":4" /> By May 1966, a total of the HARP program's 5-inch guns launched 162 flights at Wallops Island, 47 flights at White Sands Missile Range, 30 flights at Barbados, and 24 flights at Fort Greeley.<ref name=":14" />

The 7-inch HARP guns functioned as scaled-up versions of the 5-inch HARP guns that could carry three times the payload with an altitude capacity of 350,000&nbsp;ft. The 7-inch gun system was constructed from a 175&nbsp;mm [[M107 self-propelled gun|M113]] gun whose barrel was smooth-bored and extended by 26&nbsp;ft. In general, its projectiles were 1.6 m long and weighed 27&nbsp;kg.<ref name=":11" /><ref name=":14" /> However, it was also capable of firing 5&nbsp;kg slugs at a muzzle velocity of 2,880&nbsp;m/s.<ref>{{cite report|url=https://ntrl.ntis.gov/NTRL/dashboard/searchResults/titleDetail/ADA300522.xhtml|title=Ballisticians in War and Peace|last=Reed|first=Harry|date=1992|publisher=Ballistic Research Laboratory|volume=3|id=ADA300522|access-date=February 11, 2020|via=National Technical Reports Library}}</ref> The 7-inch HARP gun also incorporated the use of gun-boosted rockets to increase payload and altitude capacity. Unlike the 5-inch HARP guns, all vertical high-performance flights for the 7-inch HARP guns were conducted at NASA's [[Wallops Island]] facility, where 34 vehicles were launched by May 1966.<ref name=":14" />

The 16-inch HARP gun in Barbados held the largest gun record globally, with a barrel length of 119&nbsp;ft (36{{frac|1|4}}&nbsp;m) and weighing 200 tons. It consisted of two 16-inch U.S. Navy gun barrels welded together and smooth-bored to 16.4-inch diameter. It was capable of firing at a muzzle velocity of 2,164&nbsp;m/s (7,100&nbsp;ft/s) with a maximum acceleration at launch of 15,000 g. It launched a 181-kg shot with an 84-kg payload that could reach an altitude of 181&nbsp;km (595,000&nbsp;ft).<ref name=":8" /> For propellants, the 16-inch gun used either the solvent type WM/M.225 or the solventless M8M.225, both manufactured by Canadian Arsenals Limited. During testing, a camera station set up on the islands of [[Barbados]], [[Saint Vincent and the Grenadines|Saint Vincent]], and [[Grenada]] were used to photograph the [[trimethylaluminium]] trails released from the projectile during launch, which provided data on upper atmosphere wind velocities for different altitudes.<ref>{{cite report|url=https://escholarship.mcgill.ca/concern/reports/2514nk70j?locale=en|title=Report of the March 1965 test firing series Project HARP|last=Luckert|first=H.J.|date=July 1965|publisher=McGill University|id=SRI-H-R-9}}</ref>

The 16-inch HARP gun at Yuma Proving Ground was constructed in 1966 in order to establish a functional 16-inch gun on American soil and holds the record for achieving the highest projectile launched.<ref name=":3" /> It was almost identical to the 16-inch gun on Barbados, being 119&nbsp;ft long, but was limited by a 35-mile range restriction. However, unlike the Barbados gun, its projectiles could be recovered since they were not lost in the ocean upon their journey back down. The Yuma 16-inch gun was primarily used for flight tests, such as those testing altitude control and telemetry components.<ref name=":5" /> In 1966, the 16-inch Yuma gun underwent three firing series using wooden slugs, Martlet 2C's, and a Low Altitude High-Velocity cone.<ref name=":0">{{cite report |url=https://apps.dtic.mil/dtic/tr/fulltext/u2/654123.pdf |archive-url=https://web.archive.org/web/20181216040500/https://apps.dtic.mil/dtic/tr/fulltext/u2/654123.pdf |url-status=dead |archive-date=December 16, 2018 |title=HARP 5-Inch and 16-Inch Guns at Yuma Proving Ground, Arizona |last1=Murphy |first1=Charles |last2=Bull |first2=Gerald |date=February 1967 |publisher=Ballistic Research Laboratory |id=AD654123 |via=Defense Technical Information Center}}</ref>

{| class="wikitable sortable" style="text-align:right;"

!Round<br /> number<ref>All projectiles used for this test were Martlet 2C's, except for the ones indicated with (W), i.e. wooded slugs, and (L), i.e. Low Altitude High Velocity cone.</ref>

!Mass<br /> (lb)

!Muzzle<br /> velocity<br /> (ft/s)

!Apogee<br /> (kilofeet)

A guidance and control system were developed for the orbital mission by Aviation Electric Limited of Montreal under the direction of McGill-BRL-Harry Diamond Laboratory group. [[Infrared]] horizon sensors and sun sensors were included in calculating [[AttitudeSpacecraft attitude control|vehicle attitude]]. Information for on-board sensors was to be processed by the logic module, which provided commands to a cold gas thruster system which in turn adjusted the vehicle's orientation. The components of the guidance and control assembly were integrated into a 6.25-inch diameter test projectile. Sun sensors, horizon sensors, telemetry packs, receiving/transmitting antenna, hydraulic systems, logic modules, and gas thruster [[Spacecraft attitude control|attitude control]] systems were all test-fired to approximately 10,000 g's.<ref>{{Cite book|last=Bull, G. V. (Gerald V.)|title=Paris Kanonen--the Paris guns (Wilhelmgeschütze) and Project HARP : the application of major calibre guns to atmospheric and space research|date=1988|publisher=E.S. Mittler|others=Murphy, C. H. (Charles H.)|isbn=3-8132-0304-2|location=Herford [Germany]|oclc=24066021}}</ref>

* [[Project Babylon]] (Dr. Gerald Bull's supergun project in Iraq)

[[Category:History1962 ofestablishments in Barbados]]