Hidden Figures

The release of two widely publicized books on female computers in the early Space Age in the same year (one of them with a forthcoming movie adaptation too) has to be unprecedented. The first was Rise of the Rocket Girls, about the women who worked as human computers (a redundant term before the 1950s) for the Jet Propulsion Laboratory in Pasadena, California. The second, Hidden Figures, is about the African-American women among those who did similar work for the Langley research center in Virginia. (There’s even a third book, by Dava Sobel, that covers an earlier generation of computers who worked at the Harvard Observatory).

Both Rise of the Rocket Girls and Hidden Figures are fascinating accounts of the essential roles that female computers played in aerospace research, capturing the challenging social milieu in which they worked. Hidden Figures also manages to address the impact of segregation and discrimination in the overlapping local, regional, and national contexts surrounding the work of the computers at Langley (itself a segregated workplace). It’s a story well worth reading, before or after the movie adaptation – focusing on Katherine Johnson’s contribution to the calculations for the first orbital Mercury flight – goes into wide release in January. The trailers I’ve seen look good, though Kevin Costner as a fictional NASA manager gets to strike a literal blow (with a fire axe!) against racism that goes way beyond anything NASA management actually did for their African-American staff.

In the last chapter of Hidden Figures, Shetterly discusses having to cut the section of the book about how several of its key figures moved into human resources and advocacy to try and overcome the less obvious discrimination against women and minorities in the workforce that was still going on in the 1970s and 80s. You never know from a trailer, but I suspect the movie’s not going to end with the uphill battle for recognition and equal treatment that persisted even after Johnson’s work.

As Sobel’s made clear in some of her pre-publication publicity, the stories of female computers are less undiscovered than regularly and distressingly forgotten. The women who worked in the Harvard Observatory were well known at the time; Katherine Johnson received substantial publicity at least within the African-American press for her work on Mercury. Academic writing, including a book with Princeton University Press, has covered the work of female computers in various fora. Perhaps a major Hollywood movie will help the story stick this time.

Smart Plane, Dumb Bombs, Bad Maps?: Part Two

Back to Part One

Designed around bleeding-edge 1960s avionics  the F-111 was built to would take the guesswork out of high speed, low-level navigation. Its avionics included an inertial navigation system (INS), terrain-following and attack radars, and a navigation computer that used these inputs to determine the airplane’s current location. Since an INS tends to drift over time, due to small errors in the measurements made by its gyros and accelerometers, the F-111’s navigator provided updates by taking a radar fix on a nearby landmark, usually known as an offset aimpoint, or OAP. Though they might be taken for granted by an observer, the entire process was dependent on good maps and geodetic information. F-111 pilot Richard Crandall’s description of Operation EL DORADO CANYON, the 1986 air attacks on Libya, explains what could go wrong when the F-111 flew with bad information.

Three groups of F-111Fs were involved in the operation, two equipped with laser-guided bombs (LGBs) and a third – attacking Tripoli airport – with “dumb” bombs that would be slowed by ballutes to allow for low-level delivery. All carried the PAVE TACK laser-designating pod, which also included an infra-red camera.

An F-111F aircraft releases Mark 82 bombs equipped with ballutes over a training range in 1986. Air Force photo via Wikimedia Commons

An F-111F aircraft releases Mark 82 bombs equipped with ballutes over a training range in 1986. Air Force photo via Wikimedia Commons.

Crandall focuses on the attack on Tripoli airport, where five aircraft carrying seventy-two bombs reached Tripoli airport but only one succesfully hit the Libyan aircraft parked on the tarmac. Why? According to Crandall, the attacking planes had been provided with the distance between a very visible radar target at the airport and where their bombs were supposed to land (“the radar offset”), and that information was wrong.

The aircrew that hit the airport, hats off to them! I knew the WSO extremely well, a good friend and fellow instructor for several years. In watching his tape, he nailed the radar offset for the airport. The radar was not good at burning out flat concrete but did much better on targets with more radar reflectivity. He went to narrow sector expand mode on the offset and then switched back to the Pave Tack infrared video, and nothing appeared. He went back and checked the offset again, and still dead on. The he switched back to the Pave Tack. Every other aircraft let the bombs fly using the radar offset. Their bombs hit the airfield between the taxiway and the runway. The coordinates on the offset were evidently bad. My friend went from narrow sector to wide sector in the Pave Tack and in the right side edge of the field of view he caught sight of the IL-76s. You hear him shout “come right come right” to the Pilot who is seeing nothing except tons of anti-aircraft artillery exploding and his TFR screen. The pilot made a hard turn. As he rolls out, his WSO has fired the lasers and the bombs immediately flew off. You see in the video the Pave Tack’s video rotate to upside down due to the mechanics of the pod rotating to see the target behind the aircraft. The WSOs had to learn how to track upside down when guiding LGBs. You then see a huge explosion rip through the airplanes. That was incredible teamwork in the cockpit. Good on the WSO to switch to wide field of view—it went from a really narrow straw to a slightly fatter straw to look through, but got him onto the target.

All the aircraft attacking the Tripoli area seem to have had trouble with navigational updates, not just those at the airport. The final update by radar OAP before crossing the Libyan coastline was the island of Lampedusa, and the aircrew were given coordinates for their OAP that were off by several hundred feet. James A. Jimenez, who flew one of the F-111s attacking Bab al-Aziziyah, wrote his recollections of the mission for the December 2008 issue of Air and Space Magzine. He remembers the last radar update point as being a tower at the western tip of Lampedusa.

Our navigation system had been running sweet, but when Mike [his WSO] selected the tower, the cursors fell about one mile to the west. An error during the planning process had resulted in incorrect coordinates being issued to all crews. Mike recognized the error and did not use the coordinates to update our navigation system. His decision was probably the single greatest factor enabling us to hit our target: those who updated their nav systems based on the bad coordinates missed.

Among those who ran into trouble was one F-111 targeting the Bab al-Aziziyah barracks whose error at Lampedusa was compounded upon reaching Tripoli and which ended up a mile and half off target. Its bombs ended up hitting and damaging the French embassy.

I’m still not entirely clear on where the offset coordinates for EL DORADO CANYON came from. According to an official US Air Force history, during the F-111s first combat deployments to Vietnam the offset aiming points came from a photo-positioning database called SENTINEL DATE at the Defense Mapping Agency Aerospace Center in St. Louis, or an equivalent database called SENTINEL LOCK that was deployed to Takhli and Nakhon Phanom air force bases in Thailand. SENTINEL DATE/LOCK “provide[d] a menthod for precisely determing the latitude, longitude, and elevation of navigational fix-points, offset aim points, and targets.”

However, a student paper for Air Command and Staff College by Major James M. Giesken explains that the update points for EL DORADO CANYON were geolocated by the F-111 fighter wing staff using the Analytical Photogrammetric Positioning System (APPS), an analog system for determing the location of an object on photo imagery. APPS’s output used the WGS 84 standard datum, while the target coordinates were expressed in the European Datum used by American units in Europe, and this was the source of the location error. (There’s no source for that information in the paper, but Giesken was an instructor at the Defense Mapping School from 1986 to 1988, then aide to the director of the Defense Mapping Agency for fourteen months and executive officer for the director for another seventeen. Hopefully he had a good source for the information.)

The Analytical Photogrammetric Positioning System. From Army Research & Development, May-June 1976, p.24

An early version of the Analytical Photogrammetric Positioning System. From Army Research & Development, May-June 1976, p.24

What happened during Operation EL DORADO CANYON demonstrated the obstacles to accuracy that could not be erased by the use of advanced technology, whether in a bomb or an airplane. Regardless of the precision in the weapon, an attack was only as accurate as the underlying information – and problems with that information could end up embedded in the relationships between the very systems that were supposed to provide a more precise attack than ever before.

Smart Plane, Dumb Bombs, Bad Maps?: Part One

At The Drive‘s “War Zone” (and, before that, Gizmodo‘s “Foxtrot Alpha”) Tyler Rogoway has been regularly posting first-hand reflections on flying military jets. The latest, by Richard Crandall, covers the F-111 Aardvark, probably the leading all-weather strike aircraft of the Cold War. Designed around bleeding-edge 1960s avionics that would take the guesswork out of high speed, low-level navigation, the F-111 ended up being caught between the limits of its technology and the development of a newer generation of weapons. At the same time, its combat debut pointed to the limits of the entire system of navigational tools that military aircraft have been using ever since.

General Dynamics F-111F at the National Museum of the United States Air Force. (U.S. Air Force photo)

General Dynamics F-111F at the National Museum of the United States Air Force. (U.S. Air Force photo)

The F-111 was built to penetrate enemy airspace at low level regardless of rain, fog, or darkness. How low? Crandall recalls that “sometimes we would be flying low through the mountains of New Mexico or southwest Texas and the jet’s external rotating beacon would flash off the terrain that we were flying by and it would seem to be right next to the wingtip. Some aircrew would turn it off as it unnerved them.”

The airplane’s avionics were supposed to be interconnected to make the attack process practically automatic. While the F-111’s terrain-following radar (TFR) kept the plane 200 feet above the ground, the autopilot flew the plane from waypoint to waypoint. Upon reaching the target, the ballistics computer automatically released the F-111’s bombs when the plane reached the correct parameters (position, airspeed, delivery angle, etc.). Or, if the crew put it into manual mode, the computer showed the pilot a “continually computed impact point” (CCIP) that adjusted for wind and drift to indicate where the bombs would land if they were released at that moment. In the planned ultimate version of the F-111, the F-111D, all this equipment would be integrated in to a fully digital computer system complete with “glass cockpit” multi-function electronic displays. Even the other versions of the F-111 that flew with fully or partly analog systems included similar systems.

At the heart of the system was the airplane’s inertial navigation system (INS), a package of gyroscopes and accelerometers that provided an ongoing track of the airplane’s location. Because the INS drifted by about half a nautical mile every hour, the F-111 required regular position updates to keep itself on course. The problem of correcting for INS drift wasn’t unique to the F-111. Ballistic missile submarines updated their INS using a fix from the Loran-C radio or Transit satellite network. Tomahawk missiles used an onboard terrain-matching system called TERCOM.The Strategic Air Command’s variant of the F-111 carried an Litton ASQ-119 Astrotracker that took position fixes based on the locations of up to fifty-seven stars, day or night (as well as a more accurate INS that used an electrostatically suspended gyro).

The tactical F-111 usually took position updates by locking the non-TFR attack radar onto a pre-selected terrain feature with a known position and good radar reflectivity (called an offset aimpoint, or OAP). When everything worked, that gave the F-111 remarkable accuracy. As F-111 WSO Jim Rotramel remarked to writers Peter E. Davies and Anthony M. Thornborough for their book on the F-111, “if the coordiantes for various offset aim-points (OAPs), destinations and targets were all derived from accurate sources, the radar crosshairs were more likely to land neatly on top of them.”

Even if some parts of the system failed, the remaining elements were good enough to let the F-111 complete the mission. As Crandall explains:

Our inertial navigation system was nice, but we trained to use dead reckoning and basic radar scope interpretation to get to the target even without the INS. We had backups to the backups to the backup. INS dead? Build a wind model and use the computers without the INS. That doesn’t work? Use a radar timed release based on a fixed angle offset. We practiced them all and got good at them all.

The navigator could even use the raw, unprocessed data from the TFR, a truly terrifying process that Crandall calls a “truly a no-kidding, combat-emergency-only technique.”

Trouble with the F-111Ds avionics, which proved too ambitious for the time, meant that the US Air Force flew three other versions of the plane while trying the debug them. The first was the F-111A, which had an all-analog cockpit; the -E (Crandall: “basically an F-111A with bigger air inlets”), which added a few features; and the -F, which added more digital equipment but not the full suite of the features designed for the -D. The last of these was also upgraded to operate the PAVE TACK pod that let the plane drop laser-guided bombs (LGBs). LGBs put the terminal “smarts” for precision bombing into the weapon itself, with the bomb following laser energy reflected off the target from a beam in the PAVE TACK pod.

The US Air Force Museum in Dayton, Ohio, has a 360-degree photo of the cockpit of the F-111A in their collection here. It’s all switches and gauges, with no screens apart from those for the radar.

However, even with laser-guided bombs, the F-111F still needed the airplane’s avionics to get to the target, and those systems remained dependent on maps and geodetic information in order to ensure that INS updates and OAPs were accurate. In 1986, that would prove to be the weak link during the F-111’s combat debut.

To Part Two

Another “Smallest Aircraft Carrier”

At 131-feet in length, the helicopter landing trainer Baylander (IX-514) has been billed as the “smallest aircraft carrier” in the US Navy, if not the world, by the Navy itself, its current owners the Trenk Family Foundation, and, well, me. That claim is based on the more than 10,000 helicopter landings on the Baylander between 1986 and its retirement in 2014. But what if you want the smallest ship to regularly launch its own aircraft?

The November 1963 issue of Navy magazine All Hands crowned the 206-foot USS Targeteer (YV-3) as the fleet’s “smallest aircraft carrier.” A Drone Aircraft Catapult Ship, the Targeteer was equipped to launch and recover target drones used for gunnery practice by the fleet. The third Landing Ship, Medium (LSM) to be converted into a drone launching ship, the Targeteer was based in San Diego from 1961 to 1968, replacing the USS Launcher (YV-2, 1954–1960) and the USS Catapult (YV-1).

USS Targeteer insignia. NH 64878-KN (NHHC photo).

USS Catapult, circa 1955. NH 55065 (NHHC photo).

USS Catapult, the Targeteer‘s sister ship, circa 1955. NH 55065 (NHHC photo).

Even Targeteer‘s claim, though, is contested. The Executive Officer of the fleet tug USS Kalmia (ATA-184), which also launched and recovered drones at San Diego, wrote to All Hands to claim that its length of 143 feet entitled it to the title of “smallest aircraft carrier.” (All Hands deferred to the Navy’s official classifications. The Targeteer was a Drone Aircraft Catapult Ship, the Kalmia just an Auxiliary Ocean Tug.)

USS Kalmia underway on 16 January 1964. NH 102803 (NHHC photo).

USS Kalmia underway on 16 January 1964. NH 102803 (NHHC photo).

All three claims are weak if you are looking for a ship that launches and retrieves multiple aircraft. If, on the other hand, you are looking for the smallest Navy-crewed vessel which could land or launch a single aircraft, Baylander, Targeteer, and Kalmia all lose to the helicopter pad-equipped “Tango boats” of the Mobile Riverine Force in Vietnam. Officially designated Armored Troop Carriers (ATC)s, these were Landing Craft, Mechanized (LCM) that were modified to serve as floating armoured personnel carriers in the Mekong Delta. Some were further modified with a steel flight deck on top that ran pretty much the full length of the boat. The first helicopter landing on one of these Armored Troop Carrier (Helicopter), or ATC(H)s, took place on July 4, 1967. At 56-feet in length, which is more or less the length of a Huey helicopter, I doubt I’ll find anything smaller to claim the title.

 A U.S. Army UH-1D helicopter lands on the helicopter pad of a modified U.S. Navy Armored Troop Carrier (ATCH R-92-2) operating as part of the Riverine Mobile Force, 8 July 1967. Photography by Photographer's Mate Second Class Edward Shinton. USN 1132291 (NNHC photograph).

A U.S. Army UH-1D helicopter lands on the helicopter pad of a modified U.S. Navy Armored Troop Carrier (ATCH R-92-2) operating as part of the Riverine Mobile Force, 8 July 1967. Photography by Photographer’s Mate Second Class Edward Shinton. USN 1132291 (NNHC photograph).

Aerospace History on the Web

In a very exciting move, Aviation Week and Space Technology has put its entire magazine archive from 1916 to 2016 online (h/t the latest NASA history newsletter). It’s free for now, courtesy of Boeing, although you do have to register. The interface is pretty slick, considerably more so than Flight magazine’s archive, but unlike Flight none of the pages can be downloaded and the content doesn’t come with an encouragement to “link to, copy and paste from, and contribute to the development of this unique record of aerospace and aviation history.” Still, it’s a very cool resource while it lasts.

In the meantime, the Stuff You Missed in History Class podcast has a nice two-part interview about the Women Airforce Service Pilots during the Second World War.

The Space Review has a review of Rise of the Rocket Girls, which looks like a fascinating book about the women who worked as human “computers,” doing repetitive calculations for NASA in its early years. The story of computers,” one of very few opportunities for women with educations in mathematics at the time isn’t a new one: David Alan Grier’s When Computers Were Human is about a decade old, but this looks like a valuable addition to the story. It looks like we’re also going to get both a book, Hidden Figures, and a movie about the first African-American women who worked as NASA computers.

The Balloon That Saved The Emir

In October of 2015, a tether balloon (or aerostat) that was part of the US Army’s Joint Land Attack Cruise Missile Defense Elevated Netted Sensor (JLENS) system broke free from its moorings at the Aberdeen Proving Ground in Maryland. The 243-foot-long helium balloon led the military on a merry chase, taking out power lines with its mooring cable, before settling to the ground several hours later.


A JLENS balloon like the one that got loose over Maryland.

The JLENS balloon’s runaway escape was an embarrassment for a program that’s been labelled a “zombie,” “costly, ineffectual, and seemingly impossible to kill,” but it was hardly the first time a military aerostat has gotten loose to wreak havoc. In 1981 the first military aerostat to enter service since the end of the Second World War, a blimp with the project codename SEEK SKYHOOK and the unofficial nickname “Fat Albert,” got free of its tether on Cudjoe Key in Florida and almost lifted a fishing boat that tried to corral it free of the water before being shot down by two Air Force jets.

The SEEK SKYHOOK aerostat, which entered service in 1974, inaugurated a second era of tethered military balloons that’s already about as long as the technology’s first era – which lasted from the Japanese use of an observation balloon over Port Arthur in 1904 until the decommissioning of the barrage balloons operated during the Second World War.

SEEK SKYHOOK was an air search radar (an AN/DPS-5, to be precise) deployed to the Florida Keys to offer better warning of aircraft approaching from Cuba. Most subsequent aerostats were also intended for air defense. That included the Low Altitude Surveillance System (LASS) purchased by Kuwait in the late 1980s to add to their air defense system. The LASS, one of which was also purchased by Saudi Arabia, combined a 71-meter-long balloon built by TCOM, L.P. with a Westinghouse AN/TPS-63 radar like that used for short-range warning by the US Marine Corps. Though the LASS was intended to spot low-flying aircraft its position at 10,000 feet meant it had some capacity to watch ships or ground vehicles too.

A TCOM 71M LASS aerostat. From Flight International, 11/17 Aug. 1993, p.40

A TCOM 71M LASS aerostat. From Flight International, 11/17 Aug. 1993, p.40

That additional capacity meant it played an important part in the early hours of the Iraqi invasion of Kuwait in 1990. The LASS system was still in the testing phase, being operated by a mixed team of contractor personnel and Kuwaiti air force officers. Early on the morning of August 2, the operators watched “a big burst of light – a solid line of target returns” crossing the border. Clifford Gobbitt, a TCOM systems engineer on duty, recalled that “there was so much metal, it was saturating the display.” A few hours later the TCOM staff turned the balloon and its radar over to the Kuwaiti Air Force and began the process of extracting themselves from what was about to become a war zone. A few months later, TCOM’s vice president of marketing told Aviation Week and Space Technology that “the TCOM aerostat system got the first detection of the invasion, and that warning allowed the Emir and his family to escape.” The balloon was destroyed within the next few days, but the Kuwaitis must have been satisfied with the results. Once the war was over they put in an order for an upgrade system of the same type.

The Kuwaiti experience on the eve of the Gulf War was a preview of sorts for what would be expected from one of the stand-out successes of the war, the Joint Surveillance Target Attack Radar System (JSTARS). Like the Kuwaiti LASS, JSTARS used an aerial radar to track the movement of enemy ground forces. Unlike the LASS, JSTARS was built for that task and that task only. Only two experimental aircraft were ready when the war began, and interpreting their information was apparently not much easier than reading the radar returns the TCOM technicians had seen. Colonel Martin Kleiner, the Army’s project manager, recalled that “the aircraft was airborne, it was down-linking radar and the ground stations were receiving it. Quite frankly, we had no idea what we were looking at. Our application of the system was pretty much being developed on the fly.” Still, they proved themselves indispensable in several battles. After the war, Air Force Chief of Staff General Merrill McPeak said “We will not ever again want to fight without a JSTARS kind of system.”

August 2nd was also the swan song of balloon-borne ground surveillance radar. Though JSTARS and similar programs spawned a series of aircraft-mounted radar systems, the surveillance aerostats used by the US government in places like Afghanistan, Iraq, and the US border with Mexico tend to be designed for low-intensity conflicts and equipped with video cameras rather than radar.

When Containers Flew by Balloon

What do a mature tree and a twenty-foot cargo container have in common? In the 1970s, you could carry both away by balloon. Balloon logging, as the practice was known, had a successful niche in the West Coast forestry industry for a few decades. Cargo handling by balloon, on the other hand, was tested by the US military but never made it out of the experimental stage

Two realizations were behind the US military experiments with cargo handling by balloon. The first was that the US was grossly under-equipped to handle military cargo in large quantities anywhere other than a well-equipped modern part. The second was that the international shipping business was becoming more and more reliant on moving materials in standardized cargo containers and that what equipment the US military did have was not designed to handle containerized cargo. Experiments with mobile cranes, helicopters, hovercraft, and floating piers were all part of the search for solutions to these two problems.

Among the more radical experiments were a series of tests that used helium balloons to unload cargo containers from a container ship anchored offshore. Inspiration for what became Joint Army/Navy Balloon Transport System came from Oregon and Washington, where loggers had been reaching further and further into the backcountry by developing new ways to move felled trees. In the 1920s groundlead yarding, where a long line powered by a steam engine skidded the logs along the ground, was replaced by high-lead yarding, where the lines were strung from a tall spar tree and the logs moved through the air rather than along the ground. High-lead yarding was limited by the need to find an appropriate spar tree, but lifting logs by balloon would let loggers shift logs even where the ground was too rough and the distances too long to use high leads. Tests started in Sweden in 1956, then in Canada in 1963 with Second World War-surplus barrage balloons. In the US, Goodyear Aerospace did some early experiments but it was Raven Industries that became the main supplier to the industry in the Pacific Northwest in the late 1960s.

Balloon logging configuration from the Washington Administrative Code's "Safety Standards-Logging Operations." See other cable logging systems here

Balloon logging configuration from the Washington Administrative Code’s “Safety Standards-Logging Operations.” See other cable logging systems here.

In 1972, the Advance Research Projects Agency took notice. ARPA was the military’s high-tech incubator – later than year it would pick up the prefix “Defense” and gain its current acronym, DARPA. It hosted a conference with balloon-builders at Raven Industries to brief military officials on the possibility of using their logging balloons to lift containerized cargo. The Air Force Range Measurements Laboratory, which was already using balloons to carry instrument packages, was roped in to provide technical expertise.

For Raven, offering balloons to the military brought the company back to its roots. Founded in 1956 by staff from General Mills’s High Altitude Research Division, including the “father of hot air ballooning,” Ed Yost, Raven began its business with contracts from the Office of Naval Research to build experimental balloons. Expanding from balloons into plastics, electronics, and sewn goods, the company secured millions of dollars of military contracts for radios and other electronics.

Borrowing balloons and working crews from Raven Industries and the Bohemia Lumber Company, the Air Force flew cargo containers 1500 feet across a ravine in Culp Creek, Oregon. Returning to Culp Creek five months later, they tested the balloon’s ability to lift and move containers from a simulated ship’s cargo cell, as well as the use of a third winch (a “flying Dutchman”) to shift the balloon not just along one axis but laterally as well. Extrapolating from the 1500 foot tests they calculated that a balloon could move nine containers every hour from up to a mile offshore. Finally, the laboratory towed the balloon along a track to test its reaction to wind speeds of up to 30 knots.

From Tethered Balloon Transport System: A Proposal by William Frederick Graeter II, fig. 31

From Tethered Balloon Transport System: A Proposal by William Frederick Graeter II, fig. 31.

In 1976, the balloon graduated to sea tests off Virginia Beach. Now given the moniker of Joint Army/Navy Balloon Transport System, a logging balloon was used to lift cargo containers from a simulated container cell on a Navy LST and deposit them either aboard a nearby landing craft or on the beach 700 yards away. Though it took about four times as long as the ideal calculations had suggested, the balloon was able to do the job. Ships shifting at anchor also required repeated stops to re-position the balloon.

The next year, a commercial company halfway around the world proved that the idea of unloading cargo by balloon wasn’t a fantasy. Operated by the Yemen Skyhook Company, the balloon “Queen of Sheba” was used to unload 800 tons of cargo a day from vessels in the congested Yemeni port of Hodeida. That example, though, was not enough to overcome the mediocre signals from the Virginia Beach tests. 1976 was the height point for balloon-based ship unloading in the US.

Though the Navy had experimented with a variety of unloading techniques, they finally opted for one of the less dramatic solutions on offer. Ten existing container ships were refitted to carry two or three powerful cranes each. These auxiliary crane ships could substitute for cargo cranes aboard the containership or a port, letting the Navy use the rest of its lighterage and cargo-handling equipment as is. Though the crane ships have spent most of their time in reserve, every once in a while they are called into action to support large US operations. Five were sent to the Persian Gulf in 1991 and two went to Haiti after the 2010 earthquake to help unload relief supplies. Balloon logging, on the other hand, has kept going in various places, albeit as a specialized practice rather than a widespread innovation.

The eventual solution: the auxiliary crane ship  SS Grand Canyon State. US Navy photograph courtesy Wikipedia.

The eventual solution: the auxiliary crane ship SS Grand Canyon State. US Navy photograph courtesy Wikipedia.

Source Notes: The USDA Yearbook of Agriculture describes the origins of balloon logging here; the Forest History Society discusses balloon logging on their blog; the military experiments are summarized in detail in a Naval Postgraduate School thesis here.