Editing Project HARP (section)

=== 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
|}