A lot has changed in the 40 years since the first Hydra-Sandhawk, water launched sounding rocket launch. The Hydra-Sandhawk program ended a twenty five year infatuation with the development and water launching of rockets at the Pt. Mugu Naval Missile Center. Navy priorities changed, the Soviet Union has become a distant memory and space technologies have developed in many ways that were totally unimaginable back then. Today the most basic satellites can gather massive amounts of X-Ray data that Hydra Sandhawk payloads only touched.
It was a totally analog world back then. The Hewlett-Packard HP35, the world’s first hand held, digital calculator was unknown. Desktop computers were not even dreamed about. Aerodynamic calculations and finite element structural calculations were done using Fortran, punch cards and room sized IBM 7090s with 32K of memory. If you had 7090 access, it took a day to run a simple program and get reams of printed results. Slide rules, long hand and “just launch it” were the norm. Sounding rockets, with their complex aerodynamics and lightweight structures were not designed and verified by digital simulation. They were simply designed, built and launched, pointy end first. Their wind tunnel was the sky. A ship deployed, floating, vertical sensing, water launcher system added significantly to the unknowns.
Lets look back the beginning of the Hydra concept. Using the ocean as a launch pad to submerge rockets in seemed to have many advantages. In the late 1950s, Navy Lieut. Commander John E. Draim of the Naval Missile Center at Point Mugu, CA began experimenting with launching of free-floating rockets from the ocean. A 10 foot tall HYDRA-1 was launched in March 1960, directly out of the ocean near Pt. Mugu. There were many more development launches of solid propellant rockets conducted to further validate the Hydra, submerged rocket concept. This early project Hydra program became a foundation for the successful launching of Hydra-Iris and Hydra-Sandhawk sounding rockets from many different ocean locations.
Other sea launch concepts were evaluated. Robert Truax a pioneer rocket engineer of later Volksrocket and Evil Knieval Skycycle fame, became involved. He worked at Aerojet developing a sea launch concept for liquid propellant rockets. In October 1961, he successfully launched a SeeBee (a modified Aerobee sounding rocket) from the ocean near Pt Mugu. The SeeBee was refurbished and successfully launched again. This success led to the Aerojet Sea Horse program using much larger WAC Corporal liquid propellant sounding rockets. This in turn led to the Aerojet Sea Dragon design study. The Sea Dragon was a monstrous, 450 ft. tall, floating, two stage vehicle capable of lifting one million pounds into LEO (Low Earth Orbit).
While monstrous, sea launched LEO concepts are not yet successful, modest sea launched sounding rockets were very successful. There were several advantages of being able to launch a sounding rocket from most anywhere in the world. Hydra-Iris was the first to be deployed. The Hydra-Iris program began at the Naval Missile Center, Pt Mugu in 1962 and had eight launches. Its last launch was in 1968. It consisted of a two-stage vehicle consisting of an IRIS sounding rocket being boosted by three Sparrow missile motors. The booster system and all the Hydra-Iris flight hardware were designed by Naval Missile Center personnel. The launcher had a command-control system plus vertical sensing gyros to help keep launches vertical. The floating launcher was kind of an external “tower” design with added buoyancy. It was also designed at the Naval Missile Center. The Hydra-Iris program was a joint effort with the Lawrence Radiation Laboratory. Laboratory personnel developed and produced the upper atmosphere and X-Ray astronomy payloads.
The Hydra-Sandhawk program was funded through the Lawrence Radiation Laboratory. X-Ray measurement and astronomy payloads became more sophisticated and were produced by Laboratory personnel. The Hydra-Sandhawk launching system, the vehicle and flight hardware were totally new and had little in common with Hydra-Iris. Like Hydra Iris, it was developed and produced at the Naval Missile Center.
The Hydra-Sandhawk flight vehicle with its “off the shelf” rocket motors, its water launching system were developed and put into production literally on a “shoe string”. It came from a world of gifted designers and experienced ordinance technicians, slide rules, drafting boards, machine shops, vacuum tubes with a few transistors thrown in. There were few paths to follow.