Apply HN: Ram Accelerator Supergun Space Launch

Who: Ryan Lackey

Objective: to put satellites into LEO, materials into higher orbit, and do so at Stage: some research, no detailed plan, looking for expertise

Technology: A "Ram Accelerator" -- essentially a 10km long, 1m bore cannon, to be built in a remote location, ideally on a mountain near the equator (Ecuador? Ethiopia? Somalia?). 500 m/s chemical gun at the breach, projectile enters a tube 10km filled with ~10 different mixtures of natural gas and oxygen. Projectile is shaped like a ramjet core (cones), so it compresses/detonates fuel, causing constant acceleration. Leaves muzzle at 10 km/s. Hits atmosphere, massive boom. Projectile contains booster rocket and circularizing rocket.

Projectile peak G load is ~5-10k G, which is a non-issue for solid state/potted electronics. Deployables can be immersed in incompressible liquid fuel.

When: "Someday". I'm not an expert in aerospace/mechanical engineering, so I'd need to find solid cofounders, and would like to validate the idea more. It's been researched extensively at UW, Boeing, and other places over the past 15y. Production scale is a $50-100mm project. Subscale is maybe $5mm.

Fellowship product: Detailed computer simulation and answers to key questions (barrel erosion, payloads/capacities, costs, market)

Final Product: Probably a LEO satcom/sensing constellation, or delivered components to orbit, rather than launch services themselves, due to unique characteristics of launch platform.

Links for reference: http://ramaccelerator.org/home/ https://en.wikipedia.org/wiki/Ram_accelerator http://www.tbfg.org/papers/Ram%20Accelerator%20Technical%20Risks%20ISDC07.pdf

(I have full-time other things to do, but I wanted to write this up just to get feedback from people smarter than me.)

The bigger the bore, the lower the peak acceleration, and RAMAC is inherently a "long shove" vs. a specific impulse at the breach.

It absolutely rules out passengers, but doesn't really seem to be a big problem for components.

The much bigger problems are sound/ablation at the muzzle (hitting the atmosphere suddenly at 10km/s...), and barrel life/erosion (big battleship guns got...150 round lifespan. Barrel erosion is related to velocity. The breach of this will not have much difficulty, but the muzzle end probably won't do well. OTOH it's not rifled or otherwise close-fit, and could have "wipers" which are themselves ablative/disposable. Since there's a rocket/guidance package, it doesn't need to be as low-tolerance as an old battleship gun.

(System has been prototyped by Bull using 16" surplus battleship guns in Barbados)

(frequency access is probably the main issue there)

2) Until SpaceX, the idea of entrepreneurial space didn't exist.

3) Payload uniqueness -- this never will work for human passengers, so NASA won't fund it. The value of 1 x 100kg into LEO every hour every day for years on each launcher is not yet established.