There are a bunch of technical reports referenced online but they mostly haven't been uploaded anywhere. This one looks especially helpful and is available
on the AIAA website, but $25 is a bit steep. (Anyone have an institutional login?):
- "Grumman Design M163-A 2400 Metric Ton Air Capable Hydrofoil APR 78 Ship", by C.G. Pieroth, Grumman Aerospace Corp., AIAA/SNAME Advanced Marine Vehicles Conf., San Diego, Calif., April 17-19, 1978.
I went ahead and grabbed this report after all. Turns out it gives some interesting insight not just into the HYD-2 design but also one school of thinking about USN sensors and weapons for the early 1990s as imagined from the 1970s. Unfortunately, the image quality is terrible. I’ll include two drawings that are easy to interpret, but the text is largely illegible.
First, the ship itself. As already known, the Grumman M163 HYD-2 was an ocean-going hydrofoil escort, envisaged as a 1990s successor to the PF-109/FFG-7 design. The basic design is fairly familiar, two inverted pi foils, with the aft foil holding a pair of podded propellers and the forward foil having steerable struts. Another pair of pods contained the hullborne propulsion propellers and gearing. Construction is an aluminum hull with HY130 steel hydrofoils. Interestingly, the designers appear to have anticipated keeping the foils down whenever the water was deep enough even when not foilborne; they didn’t even bother to calculate most of the performance specs hullborne with foils up.
Propulsion machinery includes two Pratt & Whitney FT-9 turbines, which were then in development and put out about twice the power of the contemporary versions of the LM2500. Backup cruise power came from a single GE LM500, with electrical power from 3 Lycoming TF35 turbines. Everything was mechanically linked through gearboxes (which was one of the major risk areas, since the gearboxes had to handle lots of power at high RPMs and in various combinations).
Top foilborne speed as around 51 knots (reducing only slightly with increasing sea state), max hullborne speed was around 26 knots using one FT-9 or 15 knots using the LM500. Takeoff speed was around 25 knots. Range varied from 2800 nm at 45 knots (foilborne) to 3250 nm at 20 knots (hullborne using an FT-9) and 5900 nm at 14 knots (hullborne on the LM500).
Armament is interesting, and amazingly heavy for a ship of this size. They envisaged 72 “universal” VLS cells arranged two-deep along the outside of the deckhouse on both sides. These cells could carry the ASAR (MR) SAM (or presumably Standard MR), Harpoon, or ASW Standoff weapons. Nominal load was 40 SAM, 16 Harpoon, and 16 ASW weapons. In addition, there were 24 Advanced Self-Defense Missiles in vertical launchers forward of the bridge. (Note: The dark spots on the hull are plenum vents for rocket exhaust from the various vertical launchers). ASAR I’ve described in another thread. ASDM is undefined, but I think it was the notional successor to NATO Sea Sparrow. The ASW Standoff weapon was possibly Sea Lance/ASW SOW.
There were also four Mk 48 heavyweight torpedoes in canister launchers on the main deck forward of the bridge. Again, heavyweight surface-launched torpedoes had been popular a few years earlier but were disappearing again by this point. There is a magazine with 36 Advanced Lightweight Torpedoes (what became Mk 50), but no provision for launching these “over the side” so they were strictly helicopter weapons.
Notably, there is no mention of guns at all, though I’m sure I’ve seen drawing of this hull with a 5-inch gun forward.
Radars and fire control include an “advanced dual-band 2-d radar” (looks like something similar to SPS-49 but lighter and dual-band?), an “Aegis-derivative” rotating phased array (doesn’t look much like a SPY array, being wide and fairly short), one Mk 74 FCS radar, an “advanced lightweight Track-While Scan” radar (possible derived from AWG-9?), and one APS-116 surface search radar (originally an airborne periscope detection radar). There is also an unspecified anti-ship missile defense EW system.
Sonar was quite different from contemporary ships. No fixed hull sonar at all, just the ARAPS “dipping” sonar deployed on a cable below the hull, a towed array, six “deployable linear arrays,” and a number of ERAPS buoys (10 over-the-side and 26 rocket-propelled, with vertical launchers alongside the bridge). There were also 200 Type A sonobuoys for helicopters plus 10 “dropline” sonobuoys (not sure what these are).
The aviation element included two LAMPS III helos and twelve “standard ship-launched RPVs,” probably of the same type described for the smaller M165 hydrofoil. Notably, I don’t see space for the RAST hauldown system. Perhaps they thought the foils would make the ship stable enough at high sea states that RAST would not be required? I think a Harpoon-style deck lock would be needed, at minimum.