- Side
- United States and South Vietnam
U.S. Army history says 2.75-inch FFAR rockets were used by Army UH-1 Huey and AH-1G Hueycobra helicopters in Vietnam, including suppressive rocket fire from armed Huey gunships.
Munitions
2.75-inch rockets
Also known as
- 2.75-inch FFAR
- 70 mm rockets
- 70mm rockets
- Folding-Fin Aerial Rocket
- FFAR
- Hydra 70
- Hydra-70
- Hydra-70 rockets
- Mk 4 FFAR
- Mk 40 FFAR
- Mk 66 rocket motor
- Mk 66 Mod 4
The 2.75-inch rocket family covers the U.S. 70 mm unguided aerial rocket line from early FFAR/Mk 4 and Mk 40 rockets through the modern Hydra-70/Mk 66 system. Army and GD-OTS sources describe a modular air-launched rocket used with multiple warheads from fixed- and rotary-wing aircraft, while official U.S. military sources document 2.75-inch rocket use from Vietnam and Desert Storm through Iraq, Afghanistan, Operation Inherent Resolve, and U.S. aid to Ukraine.
Role in Conflicts
- Side
- Coalition forces
U.S. Army Redstone history records AH-64 Apaches firing 2.75-inch Hydra-70 rockets with Hellfire missiles against Iraqi early-warning radar sites at the opening of Operation Desert Storm.
Role details
U.S. Air Forces Central reported A-10s employing 2.75-inch rockets from Bagram, and DVIDS documented U.S. Army AH-64E crews loading Hydra 70 rockets for Afghanistan missions during Operation Freedom's Sentinel.
Role detailsU.S. Army Center of Military History accounts document AH-64 Apache crews firing and expending Hydra 2.75-inch rockets during Iraq War engagements near Taji in 2007.
Role detailsDVIDS documented U.S. Army Apache crews in Iraq loading Hydra 70 air-to-surface rockets for Operation Inherent Resolve offensive operations and fires support to Iraqi security forces.
Role details- Side
- Ukraine
U.S. Defense Department security-assistance fact sheets listed more than 20,000 Hydra-70 aircraft rockets committed to Ukraine, and 2023 reporting by TWZ and The Aviationist documented Ukrainian Mi-24 helicopters armed with U.S.-supplied 70 mm Hydra rockets.
Role detailsProfile / Specs
Profile
- Origin
- United States
- Built by
- General Dynamics Ordnance and Tactical SystemsHunter-Douglas Div., Bridgeport Brass Co.NSWC Indian Head
- Type
- Unguided 2.75-inch air-launched rocket family
- Service note
- Late 1940s-present
- Produced
- Post-World War II-present
Specifications
- Lineage
- FFAR / Mk 4 and Mk 40 to Hydra-70 / Mk 66
- Caliber
- 2.75 inches (70 mm)
- Guidance
- Unguided free-flight rocket
- System components
- Mk 66 MOD 4 rocket motor, one of nine warheads, and a point-detonating or remote-set fuze
- Role
- Air-to-ground suppression, smoke, illumination, marking, and fire support
- Modern motor
- Mk 66 MOD 4 rocket motor
- Motor dimensions
- 41.7 in (106 cm) long; 13.6 lb (6.2 kg)
- Motor performance
- 1,415 lb average thrust and 1.07 s burn time at 77 degrees F / 25 degrees C
- Launch method
- Seven- and 19-tube aircraft launchers
- Platforms
- Fixed- and rotary-wing aircraft
- Hydra-70 weight
- 23-27 lb, warhead dependent
- Hydra-70 length
- 55-70 in, warhead dependent
- Hydra-70 range
- 300-8,000 m
- Hydra-70 velocity
- 700+ m/s
- Temperature limits
- Operational -50 degrees F to 150 degrees F; storage -65 degrees F to 160 degrees F
- Warheads
- High-explosive, anti-personnel, multipurpose submunition, smoke, flechette, training, visible-light illumination, and infrared illumination options
Family Structure
The 2.75-inch family is best read as a modular rocket-and-launcher ecosystem rather than one fixed round. Early FFAR designations belong to the Mk 4 and Mk 40 folding-fin path, while modern Hydra-70 rounds center on the Mk 66 motor and mission-selected payloads.
Modern all-up round
GD-OTS describes Hydra-70 as a Mk 66 MOD 4 motor combined with one of nine warheads and a point-detonating or remote-set fuze.
Designation split
Mk 4 and Mk 40 identify the earlier FFAR line; Mk 66 / Hydra-70 identifies the later wrap-around-fin motor family.
Mission effects
GD-OTS lists training, unitary, and cargo configurations supporting suppression, obscuration, illumination, marking, and point or area target effects.
Guided branch
APKWS-class kits convert unguided 2.75-inch rockets such as Hydra 70 Mk 66 into precision-guided munitions; detailed guided-rocket coverage belongs on 2.75-inch guided rockets.
Sources: HYDRA 70 Product Brochure 2024; Air-Launched 2.75-Inch Rockets; APKWS Precision Guidance Kit.
Variants
The catalog entry treats 2.75-inch rockets as the broader unguided 70 mm aerial rocket family. Hydra-70 is the modern U.S. Mk 66-based rocket system, while guided 2.75-inch rockets such as APKWS add precision guidance to the same rocket diameter and are tracked separately.
| Variant | Configuration | Designation notes |
|---|---|---|
| Mk 4 Mighty Mouse FFAR | Early 2.75-inch folding-fin rocket | Designation Systems identifies the Mk 4 FFAR as a late-1940s Naval Ordnance Test Station rocket originally intended for air-to-air use and later adapted to air-to-ground roles. Sources: Air-Launched 2.75-Inch Rockets |
| Mk 40 FFAR | Improved folding-fin rocket motor family | Designation Systems describes the Mk 40 as a 2.75-inch motor developed for better performance and spin stability from armed helicopters and other slower launch platforms. Sources: Air-Launched 2.75-Inch Rockets |
 | Modern Mk 66-based unguided rocket system | GD-OTS describes Hydra-70 as the 2.75-inch / 70 mm family using the Mk 66 MOD 4 rocket motor, interchangeable warheads, and associated fuzes. Sources: HYDRA 70 Product Brochure 2024 |
 | Guided derivative family | BAE Systems describes APKWS as a guidance kit that converts unguided 2.75-inch rockets such as Hydra 70 Mk 66 into precision-guided munitions. Sources: APKWS Precision Guidance Kit |
Carrier Aircraft
Official aircraft fact sheets and program pages identify these catalog aircraft as carriers or launch platforms for 2.75-inch rockets and Hydra-70 rockets.
| Carrier | Carrier type | Carriage evidence |
|---|---|---|
 | V/STOL attack aircraft | The Navy AV-8B fact file lists 2.75-inch rockets among the Harrier's air-to-ground stores. Sources: NHHC AV-8B PDF Fact File |
 | Attack helicopter | The Army AH-64D/E fact sheet states that the Apache is equipped with Hydra-70 2.75-inch rockets. Sources: Army Apache AH-64D/E PDF |
 | Close air support aircraft | The Air Force A-10C fact sheet lists unguided and laser-guided 2.75-inch rockets in the aircraft's armament. Sources: Air Force A-10C Fact Sheet |
 | Multirole fighter | Shaw Air Force Base described an F-16 loadout using six LAU-131 rocket launchers capable of expending 42 2.75-inch rockets. Sources: Shaw F-16 Rocket Load Article |
 | Attack helicopter | NAVAIR reported AH-1Z and UH-1Y H-1 test aircraft firing more than 2,000 2.75-inch rockets during developmental testing. Sources: NAVAIR H-1 Development Testing |
 | Armed special operations helicopter | The USSOCOM 2021 Fact Book lists the MH-60L/M Black Hawk Defensive Armed Penetrator armament as including 70 mm Hydra rockets. Sources: USSOCOM 2021 Fact Book |
Related Rocket Systems
The 2.75-inch family connects to cataloged Hydra-70, guided-rocket, launcher, and pod records that cover narrower parts of the ecosystem.
| Compatible item | Item type | Compatibility evidence |
|---|---|---|
| Modern unguided rocket system | GD-OTS describes Hydra-70 as the modern 2.75-inch / 70 mm rocket family built around the Mk 66 MOD 4 motor, interchangeable warheads, and associated fuzes. Sources: HYDRA 70 Product Brochure 2024 |
| Guided derivative family | BAE Systems describes APKWS as transforming unguided 2.75-inch rockets such as Hydra 70 Mk 66 into precision-guided munitions. Sources: APKWS Precision Guidance Kit |
 | Aircraft launcher class | GD-OTS says Hydra-70 fires from existing seven- and 19-tube launchers, linking the rocket family to the broader 2.75-inch rocket-pod class. Sources: HYDRA 70 Product Brochure 2024 |
 | 19-round 70 mm launcher | GD-OTS identifies 19-tube launchers as part of the Hydra-70 launch ecosystem, and the M261 catalog record covers a 19-round Hydra-70 launcher. Sources: HYDRA 70 Product Brochure 2024 |
Timeline
2.75-inch rockets Key Events
Mk 66 prototype ready
Designation Systems identifies the Mk 66 Mod 0 as ready by 1972, before later production versions became the Hydra-70 motor family.
Sources: Air-Launched 2.75-Inch Rockets
General Dynamics production baseline
GD-OTS product material states that General Dynamics has produced Hydra-70 rockets since 1996 in support of the Army rocket program.
Sources: HYDRA 70 Product Brochure 2024
Hydra-70 rockets fired in Desert Storm opening
Army Redstone history records AH-64 Apaches firing 2.75-inch Hydra-70 rockets during the initial strike on Iraqi early-warning radar sites.
Sources: Redstone Desert Shield Desert Storm Role
Five-year U.S. Army production contract
General Dynamics announced a five-year U.S. Army production contract for 2.75-inch / 70 mm Hydra-70 air-to-ground rockets for all U.S. military services.
Sources: General Dynamics Hydra-70 Rocket Program Contract
More than eight million produced
GD-OTS's May 2024 Hydra-70 brochure states that General Dynamics had produced more than eight million Hydra-70 rockets since 1996.
Sources: HYDRA 70 Product Brochure 2024
Media
2.75-inch rockets Videos
2.75-inch rockets Images
Related Weapon Systems
Sources
HYDRA-70 RocketPublisher: General Dynamics Ordnance and Tactical Systems | Note: Supports the 2.75-inch / 70 mm Hydra-70 family description, Mk 66 MOD 4 motor, modular warhead and fuze structure, launcher and aircraft context, and manufacturer background. | Accessed: 2026-07-01HYDRA 70 Product Brochure 2024Publisher: General Dynamics Ordnance and Tactical Systems | Note: Supports Hydra-70 family identity, Mk 66 MOD 4 motor dimensions and performance, motor-warhead-fuze architecture, warhead options, temperature limits, seven- and 19-tube launcher compatibility, APKWS compatibility, and the production-count timeline claim. | Accessed: 2026-07-01Air-Launched 2.75-Inch RocketsPublisher: Designation-Systems.net | Note: Supports the 2.75-inch rocket lineage, late-1940s Naval Ordnance Test Station origin context, Mk 4 and Mk 40 designation structure, Mk 66 / Hydra-70 development lineage, launcher family context, and variant notes. | Accessed: 2026-07-01NASM Mighty Mouse object pagePublisher: Smithsonian National Air and Space Museum | Note: Supports the Hunter-Douglas Div., Bridgeport Brass Co. manufacturer attribution for a 2.75-inch FFAR Mighty Mouse object and provides early 2.75-inch rocket family background. | Accessed: 2026-07-11General Dynamics Hydra-70 Rocket Program ContractPublisher: General Dynamics | Note: Supports the December 2014 U.S. Army production-contract timeline entry, the Hydra-70 air-to-ground rocket production context for all U.S. military services, and General Dynamics system-integrator background since 1996. | Accessed: 2026-07-01APKWS Precision Guidance KitPublisher: BAE Systems | Note: Supports the guided-rocket family relationship and the statement that APKWS transforms unguided 2.75-inch rockets such as Hydra 70 Mk 66 into precision-guided munitions. | Accessed: 2026-07-01Army Weapon Systems Handbook 2020-2021Publisher: U.S. Army | Note: Supports Hydra-70 2.75-inch rocket-system specifications, mission roles, warhead types, aircraft employment, production status, foreign military sales context, and APKWS II as a precision guidance package for Hydra-70. | Accessed: 2026-07-01More Hydra-70 Rockets On WayPublisher: U.S. Army | Note: Supports FFAR origins, Hydra-70 fielding, Iraq and Afghanistan background, and U.S. Army procurement context for the 2.75-inch rocket family. | Accessed: 2026-07-01NSWC Indian Head Command Brief 2022Publisher: Naval Surface Warfare Center Indian Head Division | Note: Supports NSWC Indian Head production context for 2.75-inch rockets, including propellant manufacturing and warhead production. | Accessed: 2026-07-11U.S. Army Air-to-Ground Missiles in VietnamPublisher: U.S. Army | Note: 1955 Vietnam War: used by U.S. Army UH-1 Huey and AH-1G Hueycobra helicopters in Vietnam as 2.75-inch FFAR armament and suppressive fire. | Accessed: 2026-07-01Redstone Desert Shield Desert Storm RolePublisher: U.S. Army Redstone Arsenal Historical Information | Note: 1990 Gulf War: directly records U.S. AH-64 Apaches firing 2.75-inch Hydra-70 rockets with Hellfire missiles against Iraqi early-warning radar sites at the opening of Operation Desert Storm. | Accessed: 2026-07-01AFCENT Flying Tigers AfghanistanPublisher: U.S. Air Forces Central | Note: 2001 War in Afghanistan: employed by A-10s from the 74th Expeditionary Fighter Squadron during combat missions from Bagram in support of troops on the ground. | Accessed: 2026-07-01Rocket LoadingPublisher: Defense Visual Information Distribution Service | Note: 2001 War in Afghanistan: fielded by U.S. Army AH-64E crews loading Hydra 70 rockets for missions at Jalalabad Airfield during Operation Freedom's Sentinel. | Accessed: 2026-07-01Tip of the Spear Iraq 2004-2007Publisher: U.S. Army Center of Military History | Note: 2003 Iraq War: fired by U.S. Army AH-64 Apache crews during Iraq engagements, including accounts of Hydra 2.75-inch rocket firing and expenditure near Taji. | Accessed: 2026-07-01Soldiers load rockets, missiles on Apache attack helicopterPublisher: Defense Visual Information Distribution Service | Note: Supports 2014 War Against the Islamic State direct conflict use under Operation Inherent Resolve: 2014 Operation Inherent Resolve: fielded by U.S. Army Apache crews loading Hydra 70 air-to-surface rockets in Iraq for offensive operations and fires support to Iraqi security forces. | Accessed: 2026-07-01Fact Sheet on U.S. Security Assistance to UkrainePublisher: U.S. Department of Defense | Note: 2014 Russia-Ukraine War: supplied to Ukraine through U.S. security assistance, including more than 20,000 Hydra-70 aircraft rockets committed after Russia's February 24, 2022 full-scale invasion. | Accessed: 2026-07-01TWZ Ukraine Mi-24 Hydra RocketsPublisher: The War Zone | Note: 2014 Russia-Ukraine War: documents Ukrainian Mi-24 helicopters armed with U.S.-supplied unguided 70 mm Hydra rockets in an adapted M261 pod during the war. | Accessed: 2026-07-02The Aviationist Ukrainian Mi-24 Hydra RocketsPublisher: The Aviationist | Note: 2014 Russia-Ukraine War: documents Ukrainian Mi-24 use of U.S.-made Hydra 70 mm rockets with adapted M261 pods and distinguishes the observed unguided rockets from guided APKWS use. | Accessed: 2026-07-02Army Apache AH-64D/E PDFPublisher: U.S. Army | Note: Supports AH-64D/E Apache carriage of Hydra-70 2.75-inch rockets. | Accessed: 2026-07-01Air Force A-10C Fact SheetPublisher: U.S. Air Force | Note: Supports A-10C armament including unguided and laser-guided 2.75-inch rockets. | Accessed: 2026-07-01NAVAIR H-1 Development TestingPublisher: Naval Air Systems Command | Note: Supports AH-1Z and UH-1Y H-1 test aircraft firing more than 2,000 2.75-inch rockets during developmental testing. | Accessed: 2026-07-01Shaw F-16 Rocket Load ArticlePublisher: Shaw Air Force Base / U.S. Air Force | Note: Supports F-16 loading with LAU-131 launchers capable of expending 2.75-inch rockets. | Accessed: 2026-07-01USSOCOM 2021 Fact BookPublisher: U.S. Special Operations Command | Note: Supports MH-60L/M Black Hawk Defensive Armed Penetrator armament including 70 mm Hydra rockets. | Accessed: 2026-07-01US Army Latvia Hydra-70 articlePublisher: U.S. Army | Note: Supports the Hydra-70 family context and the public-domain image provenance for the rocket photos used on this page. | Accessed: 2026-06-27NHHC AV-8B PDF Fact FilePublisher: Naval History and Heritage Command | Note: Supports the AV-8B Harrier II air-to-ground stores list that includes 2.75-inch rockets. | Accessed: 2026-06-27