Military-Grade Awesome

Expand Your Radar Horizons (Part Deux)

In order to expand the radar early warning picket line out into the Atlantic, the US Air Force undertook a project to mount shore based radar systems on offshore platforms. Because of their similarity to the oil platforms in the Gulf of Mexico, they were known as the Texas Towers. A week-ish (or so) ago we took a look at the development and systems of these towers in Part 1. By summer of 1955 the first platform, TT-2, was ready for installation, and was towed out to be placed on temporary legs. Once it was jacked up into place, the permanent caisson legs could be installed.

The caissons were at least 160 feet long, with approx 48 feet embedded into the shoal, leaving 55 feet in the water, and the other 60 feet or so lifting the platform high out of the water. In addition to supporting the tower, each leg contained a 140 foot internal fluid storage tube, one filled with sea water to supply the drinking water distillation equipment. The Air Force assumed occupancy of the tower in early December of 1955, and began operation if the radars. They were able to detect targets similar to a B-47 at 50,000 feet, up to 200 nauntical miles away.¹

The towers were serviced both by ship and by helicopter. The Air Force allotted two H-21B helicopters per tower (four based out of Otis AFB and two at Suffolk County AFB, once all three towers were operational). This support was later re-designated the 4606th Support Squadron (Texas Towers). Each helicopter, when outfitted with flotation and survival gear, could carry 8 passengers or 1,550 pounds of freight out to the towers. Fuel and food were stocked enough to provide for a 30 day reserve, and there were enough spare parts to allow for the operational equipment to remain on for 45 days. Texas Tower 2 became operational as a ready aircraft control and warning station in May of 1956.

While the installation of TT-2 had been proceeding, contracts were being awarded for the other towers, with bids for towers 3 and 4 being accepted in November 1955. With only minor changes to increase storage capacity to the support legs, these towers were very similar to the existing tower. Due to the desire to integrate the future towers into the Semi-Automatic Ground Environment (SAGE) Defense System (an automated air defense system for North American, also the name of the associated network of radars, computer systems, and aircraft command and control equipment required in this system), the Aerospace Defense Command (ADC) decided that towers 3 and 4, Nantucket Shoal and Unnamed Shoal, would be the next to be built. TT-3 was ready to be towed into place in mid-1956, and was erected in place on Nantucket Shoal in August of that year. The next summer, TT-4 was installed, and so by November of that year all three towers were occupied. The Air Force, in order to cut costs, wanted TT-1 at Cashes Ledge and TT-5 at Brown’s bank to be removed from the program. By late 1956 the USAF had convinced the ADC of the change, and so the Texas Tower program became three towers only.

Since TT-2 had been operating during this time, it allowed the Air Force crews to gain some experience in the peculiarities of tower duty. Due to the constant running of generators and rotation of the radar systems, the tower structure would vibrate constantly. The three legs seemed to act as a tuning fork of sorts, amplifying the noises. This, while not exactly pleasant, did not really effect operations. The bigger issue was that of temperature inversion² in the atmosphere that caused distortion and loss of radar coverage which occurred mostly in the summertime. The crews soon adapted, and by 1959 all three platforms were declared SAGE operational. Total cost for construction  erection and equipment was figured at $13 million per tower, with operating expenses planned at $1.5 million annually.

Despite their integration into the SAGE network, all was not sunshine and roses with the Texas Towers. The tropospheric scatter communications system functioned effectively for voice communications during initial operations, but when the towers were brought into the SAGE system and tower to shore comms were sent with digitally coded signal for direct input to the SAGE computers, problems arose. Often the computers would have reception issues with the less than perfect signal quality from the towers. Several solutions were proposed, ranging from upgrading the systems to running submarine cables, but soon a larger problem overshadowed communications woes.

Since initial construction Texas Tower 4 had suffered from certain stability issues. Instead of the 55-80 foot depth of the other two towers, it stood in 185 foot deep water. To compensate for the extra length of the legs, it had been designed with extra diagonal bracing. Two of the extra braces were lost in transit out to the site, and instead of returning to the docks and fully correcting the loss, repairs were improvised on site. No doubt this contributed to the wobble that TT-4 began to exhibit under heavy winds and waves.

From 1958-1960, the Navy and various repair teams conducted inspections and repairs on the towers braces and connection bolts, with frequent interruptions for storms. The culmination of these efforts was the installation of above the water bracing that, according to the contractor, restored the tower to its original design strength of resistance to 125 mph winds and 35 foot breaking waves. But only a month after repairs were complete, in September 1960, Hurricane Donna struck the tower with winds and waves exceeding even those limits. The tower was evacuated before the storm struck, and survived, but not without damage from the rocking and a’rolling and whatnot.

Examination of the superstructure after the storm found that the strength of TT-4 was now only 55% of its design limit. Due to the extensive repairs required, the tower was set to be fully evacuated by February 1961 and essentially rebuilt. A small crew of 28 personnel, 14 Air Force and 14 contracted repair techs, remained on the platform to work on some limited repairs. Between the 14th and 15th of January 1961, Texas Tower 4 was struck by another storm packing 85 mph wind and 35 foot waves.

The vibration and impacts were greater than the damaged tower could take, and at approximately 7:20 pm on the night of the 15th one of the support legs snapped in half; where-upon the remaining legs, unable to support the un-even strain, sheared. TT-4 sank into the sea with the loss of all 28 men.³

After the loss of Texas Tower 4 and the crew on board, the fate of the towers was essentially sealed. They were quickly inspected and deemed safe, with none of the underlying structural issues present in TT-4. But the ADC was looking to cut the cost of operating the towers, and felt that new systems coming online could replace their capability, especially the increased capability in airborne early warning (AEW) coming from the Automatic Long Range Input System (ALRI). The towers would be phased out when the ALRI equipment came online in the AEW squadrons based at Otis AFB in Massachusetts.

In addition, the escape and survival guidelines week significantly beefed up for the remaining towers. Seven man survival capsules were installed on the towers (watertight pods with food, water, and oxygen for 15 days), and the tower evacuation criteria was revised so that  in the event high winds and waves were forecast, only a seven person standby crew would remain. The small crew was necessary to try and prevent the towers from being boarded by Soviet crew from trawlers that would often loiter nearby the towers.

For the next two years, the towers battles a succession of storms caused repeated evacuations, as well as damage to the radars. In 1963, when the ALRI systems came online, the ADC ordered the towers dismantled. TT-2 was decommissioned in January 1963, and TT-3 in March. The platform for tower two  was planned to be floated back to shore for salvage, but when the legs were dynamited out from under it, it sank and was not recovered. When tower 3 was taken down, the bottom deck was pumped full of urethane foam to ensure it would float, and was safely towed to shore to mete its end.

 

1. Of course, due to limitations from radar horizon, the same target flying down low, at say 500 feet, would be lost on the radar inside of 50 miles. This necessitated the supplementing of such ground based radar systems with airborne and ship-borne radars to fill the gaps in coverage.

2. Simply, when the temperature in the air increases with height instead of decreasing as typical. This creates an area where there is a mass of colder air under warmer air. An inversion layer promotes superrefraction. Less simply.

3. The website TexasTower.com has a list of the men who died in the collapse, and a brief memorial.

 

Images and research from texastower.com, which has an even more extensive history of the towers (and judging by the references, fairly well researched), Wikipediafalloutshelternyc.blogspot.com (H-21B 1 & 2), and collectair.com (H-21B 3), and the video from the Internet Archive.

  • Dean Bigglesworth

    Enjoyed reading this.

    btw did you accidentally post this a week ago and then remove it? I got the lead picture and half of the first paragraph on my phones rss feed exacly a week ago. And i do mean exactly a week ago, it appeared on my phone at 23:00, and it was exactly 23:00 when i finished reading this now.

    • Yeah, I started typing it all up (and was going to attempt to get it done last week, but I type kinda slow), but I hit the wrong button and send it straight out into the world instead of just saving the draft so I could finish it. I think it was only out there for about 5 min, dang RSS feed ratting me out!

      • deleted6250965

        Curse the RSS feed! I do some occasional writing on the internets myself so i've done the same thing…

        Also i have to mention todays F1-finale… Watch it if you didn't already. Amazing race, I don't really care who wins when the racing is good and i'm very far from an emotional guy, but it had me both cursing aloud and close to tears of joy.

        • skitter

          RSS would have just reminded me that I was looking forward to this.

  • gearz1

    That is quite a story, must have been a sad place to be stationed,even when not in a storm.

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