Nasa Dryden: Flying planes of the imagination

Behind the sliding, sand-coloured doors of a vast hangar in the Californian desert, north of Los Angeles, the US space agency houses some of its cutting edge vehicles. But these vehicles are not Nasa rockets or rovers.

Instead, the Dryden Aircraft Operations Facility (which could soon be renamed after Neil Armstrong – the first man on the Moon and an ex-Dryden test pilot) , is home to a vast fleet of aircraft that range from small propeller planes to some of the most advanced aircraft in the world.

The mission of the base is to “fly what others only imagine” and over the years it has lived up to its motto.

In the early days of supersonic flight, the huge airfield – conveniently located next to Edwards Air Force base – played a key role in pushing the X-1A through the sound barrier. The centre’s B-52 Stratofortress bomber, also dropped a large number of supersonic test vehicles, including the X-15 -world’s fastest manned vehicle.

In addition, the base has seen tests of an astounding array of experimental craft, including solar powered planes, drones fuelled by hydrogen and even planes with inflatable wings.

On top of these extreme prototypes, the base is also home to a longstanding fleet of no less extraordinary craft. Over the years, this has included a modified SR-71 Blackbird, a modified Boeing 747 designed to carry the Space Shuttle and various civilian and military planes heavily modified to carry scientific instruments.

These planes are used for everything from flights into the path of hurricanes, to trips to the edge of space. The information gathered helps in our understanding of the atmosphere, weather and climate, and vulcanology. The planes also allow Nasa to reach the edge of space in a craft that can be brought home again safely, unlike a rocket, which is usually a one-way trip.

Difficult landing

Recently, the base threw open the doors to its hangar to allow me to have a look around.

Dominating a large part of the space were two sleek, white Lockheed ER-2 craft. These pencil thin, single-engine craft are a derivative of the very high-altitude U-2 spy planes flown by the US Air Force and Central Intelligence Agency (CIA), which came to prominence in 1960 when CIA pilot Gary Powers was shot down over Soviet territory.

“With an aircraft like the ER-2, which can fly at 20km (over 70,000 ft altitude), we are above 98% of the atmosphere, so often we can simulate a near space environment from it,” says Randal Albertson, deputy director of Nasa’s Airbourne Science Programme.

The planes are also used to improve the performance of satellites, both current and planned.

“They are launched to calibrate and validate the information we are getting from [the satellites],” said Albertson. “Sometimes we go out with instruments before they go to space. We prove the concepts and the techniques.”

The ER-2s also play a vital role in earth science research because of their ability to reach the highest levels of the atmosphere at relatively slow speeds. That means they can be used for sampling missions, and to collect data from remote areas. It was an ER-2, for example, that was used to fly over the Antarctic in 1987 to provide evidence that man-made chemicals (CFCs) were responsible for a hole in the ozone layer.

While the science that the craft perform is often complex, the most difficult task for the plane is the landing.  Although it is a single seater aircraft, each mission has two pilots. One of them is onboard, in a high pressure "space" suit, for sometimes over 10 hours. The other stays on the ground, but is in mobile contact.

“He is the backup,” says Randy Albertson. “When it comes to take off and landing, he is the guy talking the pilot down. It’s a difficult aircraft to land.”

In fact, pilots describe it as like trying to wrestle the plane out of the sky. That’s because the craft only has two centrally placed wheels (the two ‘pogo’ wheels that support the wings are detached at take off), meaning it is like trying to drop a giant bicycle out of the sky. And, because it has a giant 25m (80ft) wingspan and high-lift wings, the craft almost has to stall to get on the ground. Even after touchdown, the craft must drop one of its specially strengthened wingtips to the ground.

To help in this convoluted process the space agency has recently branched out even further from rockets, to cars. It now has a modified Dodge Charger that can be used by the ground-based pilot to chase the ER-2 along the runway as a mobile control centre, calling out the distance to the ground to talk the plane down.

Still, the complexity of the landing is worth it for the science it returns. As a result, Nasa has been carrying out these delicate manoeuvres since 1981, when it first acquired the craft.

But soon, it could be displaced. Technology has moved on and Dryden now makes use of unmanned drones, similar to those widely used by the military. They will be the subject of the next Hyperdrive when we will have a close-up look at Nasa’s Global Hawk.

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