Project HARP
Project HARP, short for High Altitude Research Project, was a joint venture of the United States Department of Defense and Canada's Department of National Defence created with the goal of studying ballistics of re-entry vehicles 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.
A 16-inch HARP gun that was operated by the U.S. Army's Ballistic Research Laboratory at Yuma Proving Ground currently holds the world record for the highest altitude a gun-fired projectile had achieved.
History
Preparations
Project HARP originated as the brainchild of Gerald Bull, a renowned but controversial ballistic engineer who specialized in high velocity guns and gun propulsion systems. In the mid-1950s, Bull was working on Anti-Ballistic Missile and Intercontinental Ballistic Missile research at the Canadian Armaments and Research Development Establishment when he formulated the idea to launch satellites into orbit using an enormous cannon. Bull believed that a large supergun would be significantly more cost-effective at sending objects into space than a conventional rocket, because in addition to not needing expensive rocket motors, firing a large gun wouldn't require the missile to throw away multiple rocket stages to break through the Earth's atmosphere to reach orbit. In theory, a sabot would protect the payload during firing and later fall away as the satellite inside emerges.During the late 1950s, Bull conducted preliminary launch experiments at the CARDE using guns as small as 76mm. These experiments soon caught the attention of the U.S. Army's Ballistic Research Laboratory as well as the U.S. Army's Chief of Army Research and Development, Lieutenant general Arthur Trudeau. At the time, aircraft engineers needed more information on the upper regions of the atmosphere in order to design better jet planes. However, launching rockets into the air to collect data was generally considered costly and inefficient. 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 balloons couldn't reach to support the development of new supersonic aircraft and missile systems. By late 1960, CARDE and the Ballistic Research Laboratory conducted several feasibility studies surrounding the structural integrity of small gun-launched probes. 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.
In 1961, Bull resigned from CARDE and was hired by McGill University 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 and was given a verbal promise for a $500,000 grant from the Canadian Department of Defence Production, which was later reportedly denied due to bureaucratic opposition. 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 along with two 16-inch naval gun barrels complete with a land mount and surplus powder charges, a heavy-duty crane, and a $750,000 radar tracking system. Bull and Mordell officially announced the HARP project as a program under McGill University's Space Research Institute at a press conference on March 1962. HARP was presented as a research initiative dedicated to “developing low-orbital capacity for geodetic and atmospheric objectives." However, the project's long-term goal was to economically place satellites into orbit.
Construction
In 1962, Bull and Mordell established a McGill University research station on the Caribbean island of Barbados as HARP's main base of operations for its 16-inch super gun. 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 earth'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. As a result of McGill University's close connections with the island's Democratic Labour Party, Bull was able to meet with the Barbados Prime Minister Errol Barrow to arrange the construction of a firing site at Foul Bay, St. Philip. HARP reportedly received enthusiastic support from the Barbados government due to expectations that the island nation would become heavily involved in space exploration research.The installation of the 16-inch gun began at the newly established High Altitude Research Facility on 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 and had to be transported to the site on the U.S. Army landing ship, the Lieutenant Colonel John D. Page, with the assistance of the U.S. Army Transportation Corps, the U.S. Army Research Office, and the Office of the Chief of Research and Development. Hundreds of people from Barbados were employed to transport the two 140-ton gun tubes from the coast to the designated emplacement 2.5 miles from the beach using a temporary purpose-built railway. By late 1962, the HARP 16-inch gun was set up, and construction on workshops, storage buildings, radar installations, and other facilities neared completion. Around this time, the U.S. Army Research Office increased its financial support of the project to $250,000 per year. 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 kg test slug reached an altitude of 3000 meters in 58 seconds with a launch velocity of 1,000 m/s before coming down a kilometer off-shore.
Operations
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 that appeared on the McGill University crest. Inside the barrel of the gun, the Martlet was surrounded by a sabot, a machined wooden casing that protected the projectile as it traveled through the barrel by soaking up the combustive energy and then splitting apart in the air as the Martlet accelerated upward. 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. Several telemetry systems used in the HARP program were designed by the Harry Diamond Laboratories. 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 the damage claims made by householders, HARP fell into ill favor by much of the Barbados population.From late January to early February 1963, the 16-inch gun on Barbados conducted its first test series using the Martlet 1, the first of which flew for 145 seconds and reached an altitude of 26 km. It was the first Martlet flight to feature a radio transmitter beacon that tracked the flight of the vehicle. The second test series was conducted in April 1963 with the new Martlet 2 missiles, which set the world's new gun-launched altitude record of 92 km. Around the same time, development for the Martlet 3A began in the spring with test launches commencing in September. By the end of 1963, approximately 20 Martlet 2 missiles were launched and regularly reached altitudes of 80 km. From these tests, researchers obtained a great amount of atmospheric data as well as the internal ballistics of the 16-inch gun and the flight performance of the Martlet 2, 3A, and 3B. Impressed with the initial results of the HARP program, the U.S. Army agreed to provide $250,000 per year in funding.
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. 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 agreed to provide joint funding for the HARP program for a total of $3 million per year. However, funding for HARP reportedly faced several obstacles in the form of bureaucratic sabotage due to opposition in the Canadian government. 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 of the subsequent funding periods, the DDP repeatedly delayed funding for HARP late into the fiscal year.
The first attempts to improve the performance of the 16-inch gun at Barbados were made in 1964, primarily by increasing the length of the barrel. 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 muzzle of the first barrel, lengthening the barrel to 8.9 meters. The resulting gun system demonstrated a higher muzzle velocity at muzzle exit since the longer barrel allowed the propellant gases to push on the projectile for a longer period of time. 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 large size of the equipment. The extension almost doubled the length of the gun to 120 feet and weighed nearly 100 tons, making the 16-inch Barbados gun the largest operational artillery piece in the world at the time.
By the end of 1965, Project HARP had fired more than one hundred missiles at heights over 80 km high into the ionosphere. 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. For this endeavor, BRL designed the telemetry system that utilized sun sensors to determine the altitude of the projectile. This telemetry system would serve as an early precursor to that of the U.S. Army's Aeroballistic Dynamic Fuze.
By 1966, the HARP program had established several different launch sites around the United States and Canada, including a second 16-inch HARP gun at the Highwater Range in Quebec and a third 16-inch HARP gun at Yuma Proving Ground, Arizona.
On November 18, 1966, the HARP gun operated by BRL at Yuma Proving Ground launched an 84-kg Martlet 2 missile at 2,100 m/s, sending it briefly into space and setting a world altitude record of 179 km. This feat has remained the world altitude record for any fired projectile.
Closure
Throughout 1966, the HARP program experienced a series of funding delays caused by immense opposition from critics in the Canadian government as well as growing bureaucratic pressures. 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, equivalent to over $60 million total in 2020.| Start date | End date | Funding amount received |
| June 1, 1964 | May 30, 1965 | $1,129,932 |
| June 1, 1965 | May 30, 1966 | $2,138,432 |
| June 1, 1966 | May 30, 1967 | $2,911,861 |
| June 1, 1967 | May 30, 1968 | $155,700 |
On the American side, growing political and financial pressure caused by the 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. In November 1966, the Canadian government announced that it would pull all funding for Project HARP 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. Project HARP's assets were transferred to Bull, who started a commercial operation called Space Research Corporation to salvage his project. After HARP was cancelled, the 16-inch gun on Barbados remained on its emplacement, where it remains to this day, gradually rusting away.
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. 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, trimethylaluminum trails as well as sensors ranging from sun sensors to magnetometers.5-inch gun systems
The 5-inch HARP guns were based on a modified 120 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 kg payload to an altitude of 65 km, which consisted of radar reflective chaff to collect wind data and small radiosondes that returned radio telemetry of information like temperature and humidity as they drifted back down under large parachutes. This initial design for the 5-inch HARP gun was able to reach an altitude of 130,000 ft when tested in 1961. The 5-inch L70 smooth bore guns was the first vertical firing gun system developed under Project HARP. 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 m/s to altitudes of 73,100 m. 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 in the Caribbean. One of the 5-inch HARP guns were acquired by the Atmospheric Sciences Laboratory to measure winds in the stratosphere. The 5-inch gun was deemed successful as a low-cost launch system, costing only around $300 to $500 per launch. 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.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 ft. The 7-inch gun system was constructed from a 175 mm M113 gun whose barrel was smooth-bored and extended by 26 ft. In general, its projectiles were 1.6 m long and weighed 27 kg. However, it was also capable of firing 5 kg slugs at a muzzle velocity of 2,880 m/s. 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 1966.16-inch gun systems
High Altitude Research Facility
The 16-inch HARP gun at Barbados held the record for the largest gun in the world with a barrel length of 119 ft 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 m/s with a maximum acceleration at launch of 15,000 g. It launched an 181-kg shot with an 84-kg payload that could reach an altitude of 181 km. For propellants, the 16-inch gun used either the solvent type WM/M.225 or the solventless M8M.225, both of which were manufactured by Canadian Arsenals Limited. During testing, a camera station set up on the islands of Barbados, Saint Vincent, and Grenada were used to photograph the trimethylaluminum trails released from the projectile during launch, which provided data on upper atmosphere wind velocities for different altitudes.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 both gun loads and in free flight. The Highwater 16-inch gun was primarily used for missile-sabot structural integrity tests, charge development, and rocket grain tests as well as 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 ft, holding the record for the longest big bore artillery piece in the world.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. It was almost identical to the 16-inch gun on Barbados, being 119 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. In 1966, the 16-inch Yuma gun underwent three firing series using wooden slugs, Martlet 2C's, and a Low Altitude High Velocity cone.| Date | Round number | Mass | Muzzle velocity | Apogee |
| June 7 | 001 | 700 | 3360 | No track |
| June 8 | 002 | 800 | 3190 | No track |
| June 13 | 003 | 660 | 4810 | No track |
| June 13 | 004 | 760 | 5930 | 415 |
| June 13 | 005 | 780 | 5810 | 398 |
| June 14 | 006 | 780 | 6060 | 400 |
| June 14 | 007 | 800 | 6270 | Damaged |
| June 15 | 008 | 760 | 5630 | 375 |
| June 15 | 009 | 780 | 5850 | 410 |
| Oct. 25 | 010 | 1095 | 5250 | 310 |
| Oct. 26 | 011 | 1225 | 5950 | 410 |
| Oct. 26 | 012 | 920 | 6800 | 540 |
| Oct. 27 | 013 | 900 | 7100 | No track |
| Oct. 27 | 014 | 1275 | 5900 | 415 |
| Oct. 27 | 015 | 920 | 6780 | 535 |
| Oct. 27 | 016 | 950 | 7040 | Damaged |
| Nov. 16 | 017 | 1290 | 5900 | 396 |
| Nov. 16 | 018 | 1292 | 5900 | 395 |
| Nov. 16 | 019 | 1296 | 5850 | 415 |
| Nov.17 | 020 | 1296 | 5950 | 415 |
| Nov. 17 | 021 | 1290 | NA | Damaged |
| Nov. 18 | 022 | 1263 | 5900 | 400 |
| Nov. 18 | 023 | 1263 | 5850 | 410 |
| Nov. 18 | 024 | 922 | 6650 | 510 |
| Nov. 18 | 025 | 880 | 6400 | 490 |
| Nov. 19 | 026 | 910 | 6650 | 530 |
| Nov. 19 | 027 | 1270 | 5850 | 400 |
| Nov. 19 | 028 | 960 | 7000 | 590 |
| Nov. 19 | 029 | 1270 | NA | Damaged |
| Nov. 19 | 030 | 960 | 6350 | 480 |
| Nov. 19 | 031 | 1270 | 5650 | 367 |
| Nov. 19 | 032 | 1270 | 5650 | 370 |
| Nov. 19 | 033 | 880 | 6750 | 550 |