Editing Project HARP (section)

== Testing ==
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" />

=== 5-inch gun systems ===
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" />

=== 7-inch gun systems ===
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" />

=== 16-inch gun systems ===

==== High Altitude Research Facility ====
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>

==== Highwater Range ====
The 16-inch HARP gun at Highwater Range was established in 1964 near McGill University to conduct flight tests and other general research on the HARP guns without traveling all the way to the launch site at Barbados. Although the Highwater 16-inch gun was only capable of horizontal test flights and could not be elevated higher than 10 degrees, it was frequently used to test new and experimental launch vehicles and gun systems under each gun loads and in free flight. The Highwater 16-inch gun was primarily used for missile-sabot structural integrity tests, charge development, rocket grain tests, and for testing vehicle performance inside the gun and during the critical muzzle exit. In 1965, the barrel of the Highwater 16-inch gun was extended to a length of 176&nbsp;ft, holding the record for the longest big-bore artillery piece in the world.<ref name=":3" /><ref name=":14" />

==== Yuma Proving Ground ====
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;"
|+Performance Test of Yuma 16-inch HARP gun in 1966<ref name=":0" />
!Date
!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)
!Apogee<br /> (kilometers)
|-
|June 7
|001 (W)
|700
|3360
|No track
|No track
|-
|June 8
|002 (W)
|800
|3190
|No track
|No track
|-
|June 13
|003 (W)
|660
|4810
|No track
|No track
|-
|June 13
|004
|760
|5930
|415
|126.5
|-
|June 13
|005
|780
|5810
|398
|121.3
|-
|June 14
|006
|780
|6060
|400
|121.92
|-
|June 14
|007
|800
|6270
|Damaged
|Damaged
|-
|June 15
|008
|760
|5630
|375
|114.3
|-
|June 15
|009
|780
|5850
|410
|125
|-
|Oct. 25
|010
|1095
|5250
|310
|94.5
|-
|Oct. 26
|011
|1225
|5950
|410
|125
|-
|Oct. 26
|012
|920
|6800
|540
|164.6
|-
|Oct. 27
|013 (L)
|900
|7100
|No track
|No track
|-
|Oct. 27
|014
|1275
|5900
|415
|126.5
|-
|Oct. 27
|015
|920
|6780
|535
|163
|-
|Oct. 27
|016
|950
|7040
|Damaged
|Damaged
|-
|Nov. 16
|017
|1290
|5900
|396
|120.7
|-
|Nov. 16
|018
|1292
|5900
|395
|120.4
|-
|Nov. 16
|019
|1296
|5850
|415
|126.5
|-
|Nov.17
|020
|1296
|5950
|415
|126.5
|-
|Nov. 17
|021
|1290
|NA
|Damaged
|Damaged
|-
|Nov. 18
|022
|1263
|5900
|400
|122
|-
|Nov. 18
|023
|1263
|5850
|410
|125
|-
|Nov. 18
|024
|922
|6650
|510
|155.5
|-
|Nov. 18
|025
|880
|6400
|490
|150.3
|-
|Nov. 19
|026
|910
|6650
|530
|131
|-
|Nov. 19
|027
|1270
|5850
|400
|122
|-
|Nov. 19
|028
|960
|7000
|590
|180
|-
|Nov. 19
|029
|1270
|NA
|Damaged
|Damaged
|-
|Nov. 19
|030
|960
|6350
|480
|146.3
|-
|Nov. 19
|031
|1270
|5650
|367
|112
|-
|Nov. 19
|032
|1270
|5650
|370
|113
|-
|Nov. 19
|033
|880
|6750
|550
|167.6
|}