Abstract
Michael Fisher (DSIAC, 2015) provides a DoD technology assessment of hypervelocity projectile launch technologies — railguns, coilguns, electric light-gas guns, and combustion light-gas guns (CLGG). Key state-of-the-art benchmarks: ONR EMRG Phase I achieved 32 MJ muzzle energy with capability to launch projectiles 100 nautical miles. Mach 7.5 (2.5 km/s) demonstrated by Navy designs. UTRON CLGG exceeded 4 km/s with 400% muzzle energy increase versus conventional propellants. Electric light-gas gun reached 7.2 km/s at 10% efficiency. Three major bottlenecks identified: (1) barrel wear from arc transition heating, hypervelocity gouging, and erosion from lost galvanic contact; (2) high-g loading requirements for projectile electronics and propellant; (3) "compact pulsed power supplies for volume-constrained systems continue to be a challenge," including high energy-density capacitor development. The Navy EMRG program (BAE / General Atomics) entered Phase II in 2012 with focus on rep-rate fire and thermal management; sea trials targeted for 2016. Adapting EMRG technology to a land-based system the size of a tank may prove unachievable. Tier A as a peer-reviewed DoD technical assessment.
Key claims
- onr-emrg-phase-i: "Phase I proof-of-concept at 32 megajoules of muzzle energy, capable of launching projectiles 100 nautical miles."
- mach-7-5-demonstration: "Mach 7.5 (~2.5 km/s) capabilities for naval railgun designs."
- utron-clgg-velocity: "Velocities exceeding 4 km/s (13,120 ft/s) with 400% muzzle energy increase versus conventional propellants."
- electric-light-gas-gun: "Experimental velocities of 7.2 km/s with 10% efficiency."
- pulsed-power-bottleneck: "Compact pulsed power supplies for volume-constrained systems continue to be a challenge, including high energy-density capacitor development."
- barrel-wear: "Arc transition heating, hypervelocity gouging, and erosion from lost galvanic contact" — primary railgun failure mode at high cycle counts.
- emrg-life-cycle: "100 nautical miles initial capability target."
- terrestrial-scale-limit: "Adapting EMRG technology to a land-based system the size of a tank may prove unachievable."
Reviewer notes
Tier A as the peer-reviewed DoD technical assessment of EM launch state-of-the-art. Critical anchor for the q7 calc pass: the Navy EMRG program — which represents the largest sustained operational R&D investment in electromagnetic launch outside the EMALS aircraft catapult — has only demonstrated ~32 MJ muzzle energy at Mach 7.5 (2.5 km/s), with the dominant engineering issues being barrel wear, pulsed-power, and rep-rate. A lunar mass driver firing 200 kg payloads at 1.7 km/s requires ~290 MJ per shot (10× the Navy EMRG energy) at ~1 Hz cycle rate (vastly higher than Navy EMRG demonstrated cycle life). The closest operational analogue — Navy EMRG — was cancelled in 2021 after ~$500M investment because of cycle-life and barrel-wear issues; this is critical context for assessing the "100-launch demo" milestone Peterkin cites. The pulsed-power bottleneck is the dominant common engineering issue between Navy EMRG and a lunar mass driver. Load-bearing for our q7 capital and engineering-milestone analysis.