The U-2 high-altitude reconnaissance aircraft maintains a low profile for a variety of reasons. U-2 operating locations are remote and scant. Airshow appearances are rare. And the U-2 fleet is relatively small. So the general population is more likely to think U2 is a rock band rather than an airplane. Even those who know something about airplanes associate the U-2 with the Cold War and the Cuban Missile Crisis.
However, today’s U-2 is about as far removed from the original Dragon Lady as Bono is from Gary Powers.
“We do suffer from some perception issues,” admitted Melani Austin, the U-2 program director for Lockheed Martin. “Some misperceptions are attributable to the airplane’s name. Even though the aircraft has undergone at least seven fundamental changes in its operational history, it is still referred to as the U-2.”
To overcome some of the perception issues, Austin makes sure to include two photos in her presentations for audiences unfamiliar with the U-2. The first photo shows the cockpit of the original U-2A with all its scratched and worn dial gauges. The second photo shows the current U-2S cockpit with shiny new flat panel color multifunction displays.
“After seeing those photos, people realize we are discussing two completely different airplanes,” she continued. “I then explain that the U-2S is also a new airframe with newly upgraded systems that go beyond the cockpit improvements. More significantly, it is the only high-altitude platform that can perform certain critical reconnaissance missions.”
The last U-2A built, originally delivered to the Central Intelligence Agency in 1957, is on display at the National Museum of the US Air Force near Dayton, Ohio. The U-2 was redesigned in the late 1960s as the U-2R. The new design was forty percent larger, had more powerful engines, was easier to fly, and was much more capable than the original. Six of these U-2Rs were delivered to the US Air Force and six were delivered to the CIA from 1967 to 1968. The effectiveness of the redesigned aircraft, attrition of the older U-2C aircraft, as well as the military need reopened the production line in 1979 when Lockheed built an additional thirty-seven aircraft, including three two-place trainers. Although structurally identical to the 60s-era U-2R, the 1980s model, then designated as TR-1, was equipped with advanced sensors for tactical reconnaissance.
Thirty-four U-2s are flying today. Most were built in the 1980s as TR-1s though a few are U-2Rs built in the late 1960s. All of these aircraft were re-designated U-2S in 1999, with two exceptions. The two-seat trainer version, accounting for five airframes, is referred to as the TU-2S. The NASA version, accounting for two airframes derived from the U-2S, is referred to as the ER-2.
The end of U-2 production in 1989 marked the beginning of a host of evolutionary upgrades. One of the first and arguably one of the most significant upgrades came in the form of the F118-GE-110 turbofan engine that was integrated into the airframe in the mid-1990s. The engine was lighter, more powerful, more fuel efficient, and easier to maintain than the Pratt & Whitney J75 engine it replaced.
“We upgraded the engine out of necessity,” explained Greg Birdsall, Lockheed Martin sustainment manager for the U-2 program. “The U-2 was the last aircraft in the inventory to use the J75. It didn’t make sense economically for Pratt & Whitney to continue to support the J75 because the U-2 fleet was too small. Fortunately we had enough notice to develop an alternative engine, which just happened to benefit the U-2 in many ways.”
The 1,500-pound weight savings created by the new engine allowed the U-2 to increase time on station or to carry more fuel or more sensors. The aircraft could now carry sensors for multiple missions on a single flight. The F118 also provided additional electric power generation capacity that enabled upgrades that followed. The electrical system itself was modernized in the late 1990s. Legacy wiring was replaced with advanced fiber-optic technology, which lowered the overall electronic noise signature to provide a quieter platform for a new generation of sensors.
The Raytheon Remote Airborne Sensor, or RAS-1R, a radio frequency signals intelligence sensor was added in 2001. The color flat panel multifunction displays, referred to as the glass cockpit or Block 20 Modification, were added in 2003.
A variety of the U-2’s Mission Systems received significant upgrades in their capabilities and performance from 2000 through 2005. These systems consisted of an advanced defensive suite, the AN/ALQ-221, which protects the aircraft with a radar warning receiver combined with electronic countermeasure system; a nose-mounted synthetic aperture radar system, known as ASARS, which captures ground images from a range of 100 miles and operates in search and spot modes against moving and stationary targets; the Dual Data Link 2 system, which allows the aircraft to transmit collected intelligence to ground sites where the US Army, Navy, or Marines can have immediate access to intelligence images; an electro-optical reconnaissance system, designated SYERS, which provides very high resolution imagery from long distances at day or at night.
A radio frequency signals intelligence suite, the AN/ASQ-230, was added in 2008. This system detects, collects, processes, identifies, and geo-locates radio frequency signals automatically.
The most recent upgrade, the Cockpit Altitude Reduction Effort, or CARE program, was done in 2013. This modification involved reinforcing the airframe structure, replacing valves, changing the bleed air system logic, and altering some cockpit controls to lower the altitude the pilot experiences when in high flight, reducing the physical strain of high-altitude flight. The CARE modification thereby significantly reduces the risk of pilot decompression sickness.
“Decompression sickness was becoming more of an issue because of the longer flight durations and increased sorties pilots were experiencing for missions over Afghanistan,” explained Ross Cooper, Lockheed Martin chief engineer for the U-2 program. “Pilots were flying more sorties for longer durations, up to twelve hours.” Before CARE, pilots were flying these missions at an equivalent altitude of 29,500 feet. After the modifications, they are flying at an equivalent altitude of 15,000 feet. “So they feel a lot better when they get out of the cockpit after a long, high-altitude flight,” added Cooper.
Since the CARE modification, not one U-2 pilot has suffered from decompression sickness.
Most of the upgrades were developed, installed, and tested at Lockheed Martin facilities in Palmdale, California. The history of the U-2’s evolution is displayed in a series of system upgrade posters lining the entrance to the main U-2 maintenance building in Palmdale. As the Lockheed Martin production operations director for U-2, Brad Baughman is in charge of the operation. While upgrades still account for a portion of the work, the majority of the activity at Site 2 these days involve keeping the U-2 fleet flightworthy.
Essentially, our operation is a restoration shop,” explained Baughman. “We take the airplane apart, inspect it thoroughly for corrosion and cracks, repair and replace equipment as required, put it back together, paint it, flight test it, and return it to the fleet.”
The aircraft come in looking well-worn and depart looking factory fresh. Besides being structurally checked out and refreshed, all of the internal equipment is brought up to the latest standards.
The process, referred to as programmed depot maintenance, or PDM, requires about eleven months and approximately 15,000 man-hours. Every U-2 goes through PDM every six years or 4,000 flight hours, whichever comes first. With a thirty-two aircraft fleet (NASA does its own periodic maintenance), the requirement equates to four to six airframes being processed through Palmdale every year.
“I don’t know of another military aircraft program in which every aircraft in the fleet is completely disassembled and rebuilt on a regular schedule,” added Baughman.
The PDM process involves removing the wings and tail section of the aircraft, removing all of the internal equipment, removing the paint with plastic media blasting, and inspecting the airframe for corrosion or structural damage.
“If we see a bad rivet, we replace it,” noted Baughman. “Most inspections are visual, but we do put certain critical structures through non-destructive inspections.”
After all of the structure is inspected and repaired or replaced as necessary, the aircraft is reassembled. The internal equipment is reinstalled and functionally tested. Each U-2 completes three functional check flights with a Lockheed Martin test pilot at the controls for the first two flights. An Air Force pilot completes the final functional check flight before the aircraft is accepted back into service. The single-seat aircraft then complete a series of calibration flights for the RAS and AN/ASQ-230 sensor systems.
The rigorous maintenance process is a testament to the importance of the U-2’s unique mission and to the longevity of the structural design. The flight hours for a U-2 airframe average 17,000. The airframe with the highest flight hours was built in the 1960s with about 30,000 accumulated hours.
Surprisingly, structural integrity testing has shown that the airframes are good for at least 75,000 hours. “Here we are fifty years after the larger version of the U-2 was designed with an airplane that still has more than fifty percent of its operational life left,” noted Baughman. “The U-2 could fly another fifty years with no trouble at all.”
Lockheed Martin was asked to perform a thorough structural integrity test on the U-2 in the 1990s because the U-2 mission kept getting extended. The test involved putting more than 1,000 strain gauges on one airframe and measuring the loads in different areas to calculate the expected lifespan.
“The 75,000 hours figure is the advertised lifespan, but the majority of the airframe, excluding the empennage, was closer to 125,000 hours,” noted Cooper. “Hence, the U-2 fleet as a whole has nearly eighty percent of its structural life remaining.”
The U-2 pilot application is posted on the Internet as a US Air Force Fact Sheet. The opening paragraph highlights the importance of the mission:
The 9th Reconnaissance Wing is looking for a few officers with the professionalism and flying skills necessary to pilot the U-2 Dragon Lady and to provide our nation's decision-makers with critical high-altitude Intelligence, Surveillance, and Reconnaissance.
The longevity of the U-2 program can be credited to its effectiveness. In her presentation to those unfamiliar with the program, Austin puts the platform’s longevity in perspective: “Though the first version of the U-2 may have flown almost sixty years ago, today’s U-2 fleet has the capacity and capabilities needed for years to come.”