Seventy years ago this month, a Hermes II experimental missile, launched on a flight test out of White Sands Proving Ground, strayed from the test range and impacted near Ciudad Juarez, Mexico. The non-fatal mishap was later attributed to a breakdown in basic range safety protocol.
The V2 missile (Vengeance Weapon No. 2) was developed by Nazi Germany during World War II for the purpose of attacking Allied population centers. As such, it was the world’s first ballistic missile. History records that more than 3,100 V2’s were fired in anger, with London, England and Antwerp, Belgium being the prime targets. Approximately 7,200 people lost their lives in V2 attacks between September 1944 and March 1945.
The V2 as flown by the Third Reich measured 46 feet in length and had a maximum diameter of 5.4 feet. Launch weight was 28,000 lbs. The V2’s rocket motor produced a maximum thrust of about 60,000 lbs at sea level. Ethyl alcohol and liquid oxygen served as fuel and oxidizer, respectively. Approximately 19,000 pounds of propellants were consumed in 65 seconds of boost flight.
The V2’s payload was an explosive warhead weighing about 1,600 lbs. The fearsome missile’s kinematic performance was impressive for its time. Maximum velocity was around 5,200 ft/sec. After burnout, the rocket followed a ballistic flight path all the way to the target. Maximum altitude and range for wartime missions was on the order of 50 nm and 175 nm, respectively.
With the defeat of Nazi Germany, both the United States and the Soviet Union gained access to a large number of V2 missiles and many of the German rocket scientists who developed the weapon. The United States shipped 300 rail freight cars full of V2 missile components back home. Under Operation Paperclip, some 126 German engineering and scientific personnel were expatriated to the United States. Initially operating out of Fort Bliss, Texas and White Sands Proving Ground (WSPG), New Mexico, these men were destined to make major contributions to the American space program. Among their number was one Werhner von Braun.
Sixty-seven V2 missiles were launched from White Sands Proving Ground (WSPG) between 1946 and 1952. These flights gave the United States invaluable experience in all aspects of rocket assembly, handling, fueling, launching and tracking. Indeed, V2 rocket technology and lessons-learned were applied in the development of all subsequent American launch vehicles ranging from the Redstone to the Saturn V. WSPG V2’s were also used to conduct numerous high altitude and space research experiments. Many aerospace “firsts” were achieved along the way. The first biological space payloads, first photographs of earth from space and the first large two-stage rocket flights involved the former vengeance weapon.
Rocket system reliability was not particularly good in the 1940’s and 1950’s. For instance, only 68% of the WSPG V2 flights were considered successful. Range safety was in its infancy too. In particular, the comprehensive range safety protocol that governs flight operations at today’s test ranges did not yet exist. This state of affairs was largely due to the fact that much of the systems knowledge and operations lessons-learned required to establish such a protocol had yet to be acquired. An incident that occurred in May of 1947 serves to underscore the reliability and safety issues just noted.
The Hermes II missile (RTV-G-3/RV-A-3) was a derivative of the basic V2 vehicle. The payload was a forward-mounted, winged, ramjet engine test bed. The V2’s tail surfaces were enlarged to counter the destabilizing influence of the payload’s wing group. The idea was to get the payload up to a Mach number beyond 3 and separate it from the V2 booster. Following separation, the ramjet pack would be ignited and thrust established. The payload would then fly a programmed altitude-Mach number flight profile. While ambitious on several levels, the project was certainly emblematic of this era of aerospace history wherein all manner of ideas took to the skies.
On Thursday, 29 May 1947, Hermes II was fired from Launch Complex 33 at White Sands Proving Ground. It was approximately 1930 hours local time. It is noted that the ramjet pack was not active for this first flight. The Hermes test vehicle was supposed to pitch to the north and fly uprange. Instead, it pitched to the south and backrange toward El Paso, Texas. Post-flight analysis revealed that the new inertial guidance system employed by the Hermes missile had been wired backwards! This human error directly and adversely affected rocket system reliability.
The WSPG Range Safety Officer(RSO) had both the authority and responsibility to hit the destruct button once it was obvious that the Hermes II was errant. However, a project scientist physically restrained the RSO from doing so! Apparently, the scientist was of the (evidently strong) opinion that the test vehicle’s propellant load should not be wasted on such trivial grounds as the safety of the El Paso populace. Unimpeded now, the errant rocket continued its flight. Range safety protocol would have to be improved and understood by all participants prior to the next flight!
The Hermes II reached a maximum altitude of 35 nm on its unplanned trip to the south. During its 5 -minute flight, the vehicle overflew the city of El Paso and impacted near the Tepeyac Cemetery located 3.5 miles south of Ciudad Juarez, Mexico. The quasi-Mach 1 impact formed a crater that measured 50 feet in width and 24 feet in depth. Enterprising local residents gathered what little airframe wreckage that survived impact and sold it to souvenir seekers!
United States Army authorities quickly arrived on scene to ascertain the extent of the damage caused by the errant missile’s unannounced and unwelcome arrival. Happily, no lives were lost. Profuse apologies were delivered to and graciously accepted by Mexican government officials. The United States paid for all damages and effected a complete clean-up and remediation of the impact site.
A member of the team of expatriated German scientists who conducted the Hermes II flight test later was quoted as saying: “We were the first German unit to not only infiltrate the United States, but to attack Mexico from US soil!” Not nearly so amused, the Army tightened-up range safety protocol at WSPG in the aftermath of the international incident. Interestingly, historical evidence points to the likelihood that the Hermes II vehicle never did carry an active ramjet payload on test flights out of WSPG.