U-2: The veteran spyplane too valuable to replace

Nearly twice as wide as it is long, the Lockheed U-2 spy plane is one of the most distinctive aircraft in the United States Air Force – and the hardest aircraft to fly, earning itself the nickname “The Dragon Lady”.

The U-2’s 63ft-long (19m) thin fuselage, two high-aspect, un-swept glider-like wings, and powerful engine are designed to rocket the plane higher than 70,000ft (21km) – and, crucially, keep it there.

The U-2 operates at such height and at such a wafer-thin margin between its maximum speed and its stall speed that pilots call its cruising altitude “coffin corner”. The missions there last hours at a time.

The aircraft’s slender design is sometimes difficult to see. Often, it is covered in pods, spiky antennae, mysterious bulges and nosecones hiding the sensors, radar, cameras and communications equipment it needs to complete its missions. These different sensors can be plugged into the plane almost as if someone was building a model kit. There is an urban myth that one such bulge or pod contains a cloaking device – an electronic signal that renders it invisible to radar.

At 70,000ft and above, the “Dragon Lady” still has the stratosphere largely to itself, just as it did 65 years ago on its first flight. At these altitudes, the pilot is more astronaut than aviator. In the cocoon-like, pressurised cockpit of the U-2, wrapped in a bulky pressure suit with a large spherical helmet, the pilot breathes 100% oxygen. Some of the features of this kit can still be found on spacesuits in use today.

In air this thin the margins between living and dying are narrow. Indeed, the pilot faces the constant danger of hypoxia (lack of oxygen) and altitude-induced decompression sickness. Like any plane, the U-2 has to fly fast enough that the plane doesn’t stall and not so fast that the plane breaks up – the challenge for the U-2 pilot is that at 70,000ft there may be only a few miles an hour difference. An accidental nudge on the controls could spell disaster.

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Close to the ground the plane’s mechanical controls, easy to manipulate at high altitude, now take muscle power. The U-2’s lightweight design makes the plane liable to float over runways, bounce back into the air if the landing is too hard and very sensitive to cross winds. The weight-saving bicycle-style landing gear makes it difficult – and hard work – to keep the plane in a straight line and its wings level as it slows down. 

The visibility from the cockpit is so limited that when landing the pilot has to rely on instructions from another U-2 pilot driving a car that races on to the runway when the plane is coming into land. These chase cars have reached speeds close to 140mph (224km/h).

 

from Hacker News https://ift.tt/3a0Bx9m