Sounding rocket launchers are mostly taken for granted. They are bolted to launch pads and do their job for years. The Hydra-Sandhawk floating launcher was quite different. It was certainly the most unique rocket launcher in the world. It was a modular, mechanical, floating launching system for the mostly submerged Hydra-Sandhawk rocket. It also contained the rocket command/control system and a system for measuring the pitch rates so the sounding rocket could be launched nearly vertically. The launcher system and sounding rocket were assembled aboard ship, deployed and floated free for many hours before launch.
The old Hydra-Iris launcher design surrounded its rocket in an “erector set” like structure, not unlike the top portion of a White Sands Aerobee-Hi launch tower. This new floating launcher concept was a radical departure from that previous Hydra-Iris launcher design. Naval Missile Center engineers wanted to make the new launcher modular, have less wave induced pitching and provide improved access during rocket assembly.
A new, open launch rail design was developed for much easier launcher and rocket assembly. It was made up of many different aluminum components, all designed to be easily assembled using ball lock detent pins. Shape, buoyancy and ballasting were optimized to using models of the rocket and launcher system in the Naval Civil Engineering laboratory’s wave simulation facility. The final design was a definite improvement over the Hydra-Iris launcher. Unfortunately, later equipment additions to the launcher may have degraded its floating stability somewhat.
The launcher was deployed by connecting it to the ship’s crane at the system’s center of balance. It was disconnected from the crane using and explosive bolt after the loaded launcher was floating. Launcher recovery was accomplished using a long aluminum recovery arm. One end of the arm was connected to the launcher center of balance and the other end had a rope loop and was secured above the water for easier retrieval. If you look closely, the Trial Run photos show system deployment via the ship’s crane connection directly to the center of the launcher and recovery via the long aluminum recovery arm.
A properly designed handling and assembly dolly for the rocket and launcher system was an integral part of the launcher design. The dolly was a large steel structure that supported the rocket and launcher components as they were assembled aboard ship, without interfering with the assembled launcher. It was important for the dolly to accommodate different motor diameters and be able to properly “clock” the motors and innerstage sections together. The dolly had a variety of support points and height adjustments. It also provided for rocket component rotation during their final assembly. The dolly is clearly visible in several of the Trial Run photos and in the above photo.