CRV7

A SUU-5003 bomblet dispenser adapted to fire four CRV7 rockets. Four rocket tubes are visible, while shackles for six practice bombs are located underneath. Given both stores, pilots can train rocket and bomb fire on a single sortie.

TheCRV7,short for"Canadian Rocket Vehicle 7",is a 2.75-inch (70 mm) folding-fin ground attackrocketproduced byBristol AerospaceinWinnipeg, Manitoba.It was introduced in the early 1970s as an upgraded version of the standard U.S. 2.75-inch air-to-ground rocket. It was the most powerful weapon of its class, the first with enough energy to penetrate standardWarsaw Pactaircraft hangars. The CRV7 remains one of the most powerful air-to-ground attack rockets to this day, and has slowly become thede factostandard for Western-aligned forces outside the United States. Beginning in 2021, 83,303 stored Canadian CRV7s are slated for disposal, having been removed from service from 2005 to 2007.In 2024 the Department of National Defence is considering donating the rockets to Ukraine as military aid to defend against theRussian invasion of Ukraine.An estimated 8,000 rockets have functioning warheads, while the remainder could be used for parts or modification.

Development

The CRV7 was an offshoot of late 1950s research atCARDEinto high-performance solid fuel rockets, research performed as a part of a general program studyinganti-ballistic missiles.WithAerojet's assistance, CARDE and Bristol developed the "Propulsion Test Vehicle" to test new fuel and engine designs. This program led to the development of theBlack Brantsounding rocket,which first flew in 1960 and has had a long and successful career since then.Engineer Jose Tharayil from Bristol Aerospace is considered the driving force behind the CRV7's development and production.

In the early 1970s, CARDE and Bristol decided to use the same propellant and engine design for a new 2.75-inch rocket to equip theCanadair CF-104 Starfighter.The resulting RLU-5001/B (C-14) engine was first delivered by Bristol in production form in 1973. It had a total impulse of 2,320 lbf·s (10.3 kN·s) and a burn time of 2.2 seconds. The empty weight of the rocket is 6.6 kg, and it is normally equipped with a 10 lb (4.5 kg) high-explosive warhead taken from U.S. rockets.

A British ArmyAugustaWestland Apache AH.1attack helicopter of the Army Air Corps in Afghanistan fires rockets at insurgents during a patrol in 2008.

Compared to the U.S.Mk 40 FFARMighty Mouserockets the CRV7 replaced, the higher energy fuel and newer fuselage design led to a longer and much flatter trajectory, with twice the energy on impact. Its maximum effective range is over 4,000 m, allowing launch from beyond the envelope of most short-range anti-aircraft weapons. In comparison, the Mighty Mouse orHydra 70requires launches from much shorter ranges, potentially placing the launch aircraft within the range of ground-based weapons arranged around the target.

Unguided rockets are normally spin stabilized like rifle bullets. The spin is imparted by small fins at the rear of the rocket body that flip out into the airstream once the rocket leaves its launch tube. The fins take a short time to open and more time to start the rocket spinning. During this period, the rockets can drift significantly from their original aim point. The CRV7 solved this problem by adding small vanes projecting into the rocket exhaust to start the rocket spinning even before it left the launch tube, greatly increasing accuracy. A salvo of CRV7's will impact the target area in one-third the footprint of older designs.

The weapon was originally quoted to have a dispersion of 4milliradians,but testing with theMcDonnell Douglas CF-18 Hornetdemonstrated it was even lower, at 3 milliradians.This is considerably better than theautocannonthat arm most aircraft; the widely used 20mmM61 Vulcanis rated at 8 milliradians, while the much larger and considerably heavier 30mmGAU-8 Avengeris rated at 5 milliradians.

The CRV7 had just been introduced intoRoyal Canadian Air Forceservice when it was entered as a part of a general competition in France. One part of the competition required the contestants to hit a tower with unarmed rockets. The Canadian pilot hit it on his first try, but aimed as if firing the much lower-powered Mk 40 and was therefore close enough that the rocket motor was still firing. The remaining unburned propellant shattered, allowing more surface area of the rocket motor to burn, in turn increasing the pressure and rate of combustion until it became a deflagration that destroyed the tower. The pilot was disqualified because the judges refused to believe it was unarmed.

Engine development

Thealuminium-based fuel in the C-14 engine generated considerable amounts of smoke. While suitable for high-speed aircraft that quickly clear the plume, it is not suitable for slower aircraft andhelicopterswhich would be flying in the smoke for some period of time. This problem led to the development of the RLU-5002/B (C-15) engine, which did not include aluminium and produced considerably less smoke, with a slightly lower impulse of 2,185 lbf·s (9.7 kN·s).The original C-15 used a tail-mounted igniter that was ejected by the rocket when it was fired. In some cases the igniter would hit the aircraft, causing minor damage. To address this, the RLU-5002A/B (HEPI) was introduced, with a "Head-End Permanent Igniter" that is not ejected on launch.

The latest C-17 and C-18 engines for helicopter use offer somewhat lower impulse at 1,905 lbf·s (8.5 kN·s), but with almost no smoke at all.

Warheads

A British Army WAH-64 'Apache' attack helicopter fires a salvo of CRV7 (Practice) rockets at targets down range during a two-day live firing exercise at Lulworth Ranges/Bovington Camp in Dorset.

The primary warhead for the original CRV7 was the U.S. M151 High Explosive Point Detonating (HEPD) round, a simple impact-fired 10 lb (4.5 kg)high-explosiveshell. Like the U.S. 2.75-inch (70 mm) weapons, the CRV7 could also be equipped with the M156 Smoke or M257/278 Illumination (flare) rounds. Bristol also introduced their own WTU-5001/B Practice round, consisting of an 8 lb (3.6 kg) flat-ended soft steel rod encased in a nylon fairing, and later introduced a similar version with a hardened steel rod, the WTU-5001A/B.These rounds matched the ballistics of the M151 for training purposes and were widely used during the development and introduction of the weapon to the Canadian Forces.

Bristol followed this with the 16 lb (7.3 kg) WDU-50001/B "Anti-Bunkerette" round, asemi-armor-piercing high-explosive incendiary(SAPHEI/HEISAP) warhead designed for use against reinforced concrete buildings, specifically hardened aircraft shelters. Its heavy steel shell allows the round to penetrate the hangar wall before the 75 g incendiary warhead is ignited.The round can penetrate 13 ft (4.0 m) of earth, 3 ft (91 cm) of concrete, and 1 in (25 mm) of steel, in series.

The CRV7's kinetic energy was so high that testers were surprised to find that practice rounds fitted with an 8-inch (20.3 cm) steel rod were penetrating outdated Centurion tanks used for target practice. This resulted in the development of a dedicated antitank warhead that replaced the steel rod in the practice warhead with a tungsten rod. This new antitank warhead could penetrate a SovietT-72main battle tank armour from any attack angle. Further study into this effect led to the WDU-5002/B FAT warhead,Flechette Anti-Tank,containing fivetungsten-reinforced steelflechettesthat could penetrate a T-72's side and top armour at a distance of 10,000 feet (3,000 m). It was also found to be a useful warhead for use against medium and light armoured vehicles.Further development led to the WDU-500X/B "General Purpose Flechette" which releases 80 tungsten flechettes that can penetrate 1.5 inches (38 mm) of roll-hardened armorfor use against personnel, some light armour, thin-skinned vehicles, and helicopters.

Bristol also re-sells the RA-79 from Raufoss Ammunisjonsfabrikker, a semi-armor-piercing round designed to attack shipping.

The CRV7 Multi-Purpose Sub Munition (MPSM) contained nine M73 submunitions in each rocket. It could therefore be classified as acluster bomb.Britain destroyed the last of its CRV7 MPSMs in July 2009 in accordance with its interpretation of theConvention on Cluster Munitions.

Guided version

In 2006 Bristol started testing a new version of the CRV7, theCRV7-PG.The weapon was introduced atEurosatory2006.Bristol's current owners,Magellan Aerospace,offered it for sale starting in 2007.

The PG version, for "precision guided", adds a seeker developed byKongsberg Defence & Aerospaceto the front of any version of an otherwise unmodified CRV7. The seeker uses a simpleinertial guidancesystem through the midcourse and homes during the terminal approach using alaser designator.Other versions offer anti-radiation seeking or GPS guidance. The precision guided kit includes the addition of tail fins and an in-flight control system. Combining the laser seeker with the FAT warhead produces a capable long-rangeanti-tank missilethat is faster and much less expensive than traditional platforms like theAGM-114 Hellfire.

A version of the CRV7-PG was also developed forspecial forcesuse, fired from a single tube mounted on a 6 x 6 vehicle.

See also

• Mk 4/Mk 40 Folding-Fin Aerial Rocket(Mighty Mouse)
• Hydra 70
• Forges de Zeebrugge
• SNEB rocket (68 mm)
• Vought HVM
• S-8 (rocket)

References

Notes

Bibliography

• CRV7 Rocket System: Fixed Wing(PDF),Magellan Aerospace Corporation, February 2009, archived fromthe original(PDF)on 2011-07-06
• CRV7 Rocket System: Rotary Wing(PDF),Magellan Aerospace Corporation, March 2009, archived fromthe original(PDF)on 2011-01-24

External links

• CRV7 Rocket System - Bristol Aerospace
• CRV7 Rocket Motors
• CRV-7 page on the RAF official site shows the modern version's complete lack of smoke