Reentry Vehicle Development Leading to the Minuteman Avco Mark 5 and 11

Due to classification issues caused by current world events, the third generation Air Force reentry vehicle designs are not discussed in this article though they have been described in great detail in an earlier article by Lin.1 Early Research While bombardment rockets have been used for centuries, it was not until the creation of the German V-2 (also known as the A-4) that the warhead needed thermal protection due to reentry into the Earth's atmosphere.2, Since the entire V-2 impacted the target, there was no true separable reentry vehicle.3 The original design called for the use of a lightweight alloy of magnesium and aluminum but wind tunnel tests indicated that from an altitude of 43 nautical miles, the operational maximum altitude, reentry into the lower atmosphere at 3,345 miles per hour would result in a warhead compartment skin temperature of 1,250 degrees Fahrenheit. [...]the decision was made to use 1/4 inch sheet steel resulting in the need to decrease the explosive payload to hold the total warhead weight to 2,200 pounds (the steel casing weighing 550 pounds). The first chamber is separated from the second with a burst diaphragm calculated to burst when the gas in the first chamber is compressed to a predetermined value. Since 1949, shock tubes have been used to augment aerodynamic studies using hypersonic wind tunnels, in particular the use by the mid-1950's was focused on reentry vehicle design and material selection since speeds greater than Mach 10 could easily be achieved, as well as much higher temperatures. A considerable amount of radiative heat still had to be dissipated. Since radiation varies as the fourth power of the temperature, it was likely that the reentry vehicle would not be an efficient radiator with the result that surface temperature would rise beyond either the structural stability of then currently available materials or the tolerance level of the enclosed equipment, i.e., fusing and actual warhead. [...]the Navy was focusing, unlike the Air Force and Army reentry vehicle designs, on a reentry vehicle that did not encase the warhead.