- Yes
- No
History
During the Cold War, the U.S. Army made few efforts to replace the M551 Sheridan. Probably the famous one is the Armored Gun System (AGS) program. It started with modifying Sheridan with 105 mm M68 gun, which was not successful and led to the new development.
Cadillac Gage, Teledyne Continental, FMC Corporation and Team Hägglunds USA participated in this program, and the FMC awarded the contract on 14 June 1992. The first XM8 prototype was delivered to the Army on April 1994.
But the future of the AGS program was shadowy. The end of the Cold War reduced U.S. military spending, and eventually killed the XM8. Given that the AGS program was on track for both schedule and cost, it was just a scapegoat to free up budget for other modernization efforts.
Despite of the failure, United Defense Industries continued to work on XM8. The M8 Thunderbolt was built in 2003, presenting 120 mm smoothbore gun and hybrid electric drive. Later the Picatinny Arsenal and BAE Systems modified the Thunderbolt to Lightning Bolt, for developing electro-thermal chemical propulsion technologies.
Design
The Lightning Bolt is a experimental vehicle based on M8 Thunderbolt, for testing electro-thermal chemical launcher.
Electro-Thermal Chemical Propulsion
The ETC propulsion is an alternate, improved method for firing large caliber ammunition. In conventional ammunition, low electrical power sets off a primer cap, igniting propellant. This could take as long as 30 milliseconds, and it effects accuracy particularly when the barrel is vibrating.
On the other hand, the ETC ignition utilizes plasma injector in place of traditional ignitor. The bridge wire attached between two electrodes, and it initiates a high-temperature plasma discharge which vents into the surrounding propellant. This electrically conductive plasma transfers energy into the propellant more quickly and repeatably.
Compared to conventional propulsion method, ETC also has the advantage of relatively little change in ballistic velocity as the temperature drops.
The key element of the Lightning Bolt is a Electro-Thermal Ignition Pulsed Power Supply (ETIPPS). It is a capacitor-based pulsed power supply, mounted on back of turret. This enables an electro-thermal igniton shot every 5 seconds. It was first demonstrated in August 2004, with 14 live firings.
Engine and Power Train
The Lightning Bolt utilizes hybrid-electric drive (HED). This was first demonstrated on United Defense L.P. Transformation Technology Demonstrator (TTD) and applied to the M8 Thunderbolt.
At that time, they’ve implemented a propulsion system which could produce more than 500 horsepower, by two 250 hp traction motors driven by the 250 hp engine/generator and 200 kW of power.
As a result, the power train was totally revamped. The 300hp diesel engine sits in the left sponson, and 24 lead-acid 6TMF batteries are on the opposite. These drives two traction motors on the front of the hull.
Due to the nature of this propulsion method, it is also possible to turn off the engine and run quietly on batteries alone.
The powertrain change left a significant portion of the existing engine compartment space. This space could be utilized for transporting infantry or loading ammunition.
Armament
The 120 mm XM291 gun is coupled with autoloader, which holds 18 ammunition. This was only capable of carrying 15 rounds, but modified by United Defense L.P. to increase its load capacity. It supports rate of fire up to 12 rounds per minute.
The gunner sight is basically same, but it features 2nd-generation thermal device by the NV-80 B-kit upgrade package.
Specifications
Crew: 3 (commander, gunner, driver)
Length (hull): 241.9 in (6.14 m)
Weight:
- Level 1: 40,000 lb (18.1 t)
- Level 2: 45,000 lb (20.4 t)
- Level 3: 53,000 lb (24 t)
Height: 100 in (2.54 m)
Propulsion: hybrid electric drive
- Engine: John Deere diesel engine (300 hp)
- Batteries: 24× 6TMF
- Traction motor: 2 (~600 hp?)
Armor: 5083 aluminum alloy, with three levels of applique armors
Armament: 120 mm XM291 smoothbore gun
- Muzzle velocity: 1,710 m/s
- Rate of fire: 12 rpm
- Loading system: automatic
Ammunition: 18× 120 mm rounds (all in autoloader)
- M829A2 APFSDS-T (modified with coaxial plasma injector)
Fire control equipment:
- FLIR: 2nd gen
Sources
- AA 2006: 120 AGS comes to Singapore by C.F. Foss
- Jane’s International Defense Review, Volume 36
- M8 Armored Gun System brochure
- Recent Activities in Electro-Thermal Chemical Launcher Technologies at BAE Systems by Jahn Dyvik, Juleigh Herbig, Randall Appleton, John O’Reilly and Jonathan Shin
- Technical Report ARCCB-TR-00016 Recoil Considerations for Railguns by Eric L. Kathe
- Sheridan: A History of the American Light Tank by R. P. Hunnicutt
- US Battle Tanks 1946–2025 by Steven J. Jaloga
- U.S. Army World-Wide Strategic Operational Maneuver for the 21st Century
- https://x.com/ronkainen7k15/status/1457269864016400384