The Trial Run

It was a beautiful sunny day of the California coast. A trial run, or “dry run” of the complete Hydra-Sandhawk system was conducted to make sure that all mechanical systems, subsystems and electronics fit together and functioned properly in a shipboard environment. This was done before any live ordinance or a real payload was committed to being deployed. This trial run was short expedition to the ocean near San Nicolas island off the Southern California coast. A series of launcher and rocket sub-assembly fit tests and all up floatation tests were conducted prior to this trial run.

The trial run was done aboard the USS Norton Sound (AVM-1). The Norton Sound was an ideal ship for Hydra Sandhawk operations because of it being a converted sea plane tender with a very substantial and controllable crane. The crane and experienced ship”s personnel made deployment and recovery operations relatively easy. The USNS Wheeling (T-AGM-8) was also used for some Hydra-Sandhawk work, but it needed the installation and removal of a large crane for each operation.

The attached photos show most of the assembly, deployment and recovery operations. All the objectives of the operation were successfully met. Live operations would look the same except there would be a midnight launch and the empty floating launcher would be recovered the next morning.

Data were also gathered on a continuing problem with the Sandhawk”s fins. These fins were not regular Sandhawk fins although they followed that basic aerodynamic design. These fins were specifically designed and developed for Hydra operations and used honeycomb composite construction. It was found that the fins could adsorb water and special waterproofing processes were required. Unfortunately, complete waterproofing was very difficult to achieve as this trial run had shown.

The real concern about small amounts of water inside the Sandhawk”s fins was not the extra weight. Sounding rockets are spin stabilized by their fins. The real concern was that as the Sandhawk went through maximum aerodynamic pressure, the high fin temperatures would rapidly boil any entrapped water, causing a fin joint separation, followed by aerodynamic loading failure of a section of the fin. A missing piece of fin could cause significant vehicle stability problems as the sounding rocket left the atmosphere.

Enjoy the photos!
(Click on the photo above for a slideshow)