Posted on 12/24/2015 12:25:47 AM PST by sukhoi-30mki
In the early 1970s, with the Vietnam War winding down, the U.S. Navy worried about how to keep its fleet effective during the inevitable budget drawdown at war's end. Their innovative solution: build small, fast ships that could, thanks to new technologies of the time, tackle the missions once performed by much larger ships.
The Navy had studied hydrofoil ship concepts for two decades. Hydrofoils were large joined wings that lifted the ship into the air, above the water, at high speeds. Mostly free of the drag imposed by sitting in liquid, a hydrofoil ship could go much faster than an ordinary vessel. (They're used today in boat races like the America's Cup.)
Thus were born the Pegasus class Patrol Hydrofoil Missile (PHM) ships. The ships were positively tiny: 255 tons, 133 feet long and just 28 feet wide. The ships were crewed by four officers and just 17 enlisted men.
In regular cruise mode, without the hydrofoils deployed, two Mercedes-Benz marine diesels provided a total of 3,200 horsepower, or about 12 horsepower per ton of ship. That worked out to an unimpressive 12 knots an hour. When the hydrofoil was deployed, however, a General Electric LM2500 gas turbine kicked in, giving the vessel an impressive 70 horsepower per ton. That power-to-weight ratio, together with low drag, meant that Pegasus ships could pull 48 knots in hydrofoil mode, the equivalent of 55 miles an hour on the road. That was much faster than the fastest Navy ships of the era, which maxed out at about 33 knots.
The Pegasus also had a lot of firepower. Forward of the bridge was a single 76-millimeter rapid fire gun, capable of kicking out 80 rounds per minute at ranges of up to five miles. On the rear deck the Pegasus had up to eight UGM-84 Harpoon anti-ship missiles, each of which could cripple a destroyer at ranges of up to 75 miles.
The six ships of the Pegasus class—Pegasus, Hercules, Taurus, Aquilla, Aries, and Gemini—could certainly sink big ships. But the Navy soon realized that was pretty much all they could do. They couldn't operate with the rest of the fleet, hunt submarines, shoot down enemy aircraft, or do all the other things corvettes, frigates, and destroyers could. Pegasus was a one-trick pony, and her trick could be done by other platforms, including missile-carrying aircraft that the U.S. Navy already had in the hundreds.
Hydrofoil Navy ships were a technical success, but failed to find their footing. In the end, all six ships were posted to Key West, Florida, where they participated in counter-drug operations and even the U.S. invasion of Grenada. At the end of the Cold War, the ships were retired and not replaced.
That worked out to an unimpressive 12 knots an hour.
A quibble, but this is wrong. A "knot" is a nautical mile (2000 yards. 1 minute of latitude) per hour. A "knot per hour" would be a unit of acceleration.
We could use a few score of these now: instead, we have gold-plated “frigates” like the LCS.
There was one very significant problem with these boats- if the foils hit almost anything, when in use, the boat was crippled. A submerged log (and not a very big one) almost sunk one. They were just too fragile.
Greart anti-pirate intercepters, and anti submarine convoy protectors. Just put some drum style depth charges on the tail fan. :-)
Any foil malfunction at speed would be all she wrote. The stresses would be tremendous.
Reminds me of this crazy Russkie vehicle with no foils, though.
https://en.wikipedia.org/wiki/Ground_effect_vehicle
The Caspian Sea Monster! What a concept!
“We could use a few score of these now: instead, we have gold-plated “frigates†like the LCS.”
Would be fun to chase down drug runners in their cigarette boats ....
It would be awesome if you could build a carrier and its support group on this concept.
“We could use a few score of these now: instead, we have gold-plated “frigates†like the LCS.”
Would be fun to chase down drug runners in their cigarette boats ....
With some radar planes overhead, I’m sure we could solve a lot of problems. :D
I failed at linking.
https://youtu.be/irJGKY_ZnHE?list=UUJgTOIQItE_z_uni4Gcon6A
You beat me to it. Any writer in any kind of technical mag ought to know that.
Idiot.
That link is to some unlimited hydroplanine race dash cam. Enjoy.
Thanks for that.
I was a kid in the ‘50’s and remember when they were prob driven and used surplus WWII aircraft engines. When did they make the change to gas turbines?
Bill Muncie’s name just came to me. Will have to google him.
More accurately stated, a “knot” is a speed equivalent to 1 nautical mile per hour.
Yeah, Bill Muncie. He won a few times, I think, in the Gold Cup Unlimited hydroplane races on the Detroit River.
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.