Editing LGM-30 Minuteman (section)

=== Edward Hall and solid fuels ===
Minuteman owes its existence largely to Air Force Colonel [[Edward N. Hall]], who in 1956 was given charge of the solid-fuel-propulsion division of [[Bernard Adolph Schriever|General Bernard Schriever's]] [[Western Development Division]], created to lead development of the [[SM-65 Atlas]] and [[HGM-25A Titan I]] ICBMs. Solid fuels were already commonly used in short-range rockets. Hall's superiors were interested in [[short range ballistic missile|short-]] and [[medium range ballistic missile|medium]]-range missiles with solids, especially for use in Europe where the fast reaction time was an advantage for weapons that might be attacked by Soviet aircraft. But Hall was convinced that they could be used for a true ICBM with a {{convert|5500|nmi|adj=on}} range.<ref name="1990_MacKenzie" />{{rp|page=152}}

To achieve the required energy, that year Hall began funding research at [[Boeing]] and [[Thiokol]] into the use of [[ammonium perchlorate composite propellant]]. Adapting a concept developed in the [[United Kingdom|UK]], they cast the fuel into large cylinders with a star-shaped hole running along the inner axis. This allowed the fuel to burn along the entire length of the cylinder, rather than just the end as in earlier designs. The increased burn rate meant increased thrust. This also meant the heat was spread across the entire motor, instead of the end, and because it burned from the inside out it did not reach the wall of the missile fuselage until the fuel was finished burning. In comparison, older designs burned primarily from one end to the other, meaning that at any instant one small section of the fuselage was being subjected to extreme loads and temperatures.<ref name="Maugh" />

Guidance of an ICBM is based not only on the direction the missile is traveling but the precise instant that thrust is cut off. Too much thrust and the warhead will overshoot its target, too little and it will fall short. Solids are normally very hard to predict in terms of burn time and their instantaneous thrust during the burn, which made them questionable for the sort of accuracy required to hit a target at intercontinental range. While this initially appeared to be an insurmountable problem, it ended up being solved in an almost trivial fashion. A series of ports were added inside the rocket nozzle that were opened when the guidance systems called for engine cut-off. The reduction in pressure was so abrupt that the remaining fuel broke up and blew out the nozzle without contributing to the thrust.<ref name="Maugh" />

The first to use these developments was the US Navy. It had been involved in a joint program with the [[US Army]] to develop the liquid-fueled [[PGM-19 Jupiter]], but had always been skeptical of the system. The Navy felt that liquid fuels were too dangerous to use onboard ships, especially submarines. Rapid success in the solids development program, combined with [[Edward Teller]]'s promise of much lighter [[nuclear warhead]]s during [[Project Nobska]], led the Navy to abandon Jupiter and begin development of their own solid-fuel missile. Aerojet's work with Hall was adapted for their [[UGM-27 Polaris]] starting in December 1956.<ref name="2001Teller" />