Exploring the Remains of England’s Top-Secret Turbine Testing Site

The heavy doors of Cell Number 3, as seen in the movie, Sahara

In the clearing of a small wooded area between the towns of Fleet and Farnborough in Hampshire, England stands a deserted structure of concrete, metal and glass. Abandoned and decaying, the building is nonetheless imposing. And for reasons that will become obvious as you look through these photographs, the location is a magnet for intrepid urban explorers. In its day, it was a top-secret facility, and the site is still prowled by security guards. Fortunately, photographer Don Kiddick agreed to share his amazing photographs with us so that, unlike him, we can explore this fascinating place without risk.

An intriguing-looking capsule

Although all is quiet here now, for over half a century the National Gas Turbine Establishment at Pyestock saw all kinds of turbine engines pass through its doors. Everything from Royal Navy turbines to Concorde engines were tested in specially built chambers on site. Even captured Soviet engines were examined here discreetly. During its operational years, the importance the facility held to both the national security and commercial air transport sector of Great Britain cannot be overestimated.

No more flying for this plane

Once a golf course, Pyestock was chosen for its secluded location, which made it ideal for the secret research that was conducted there. The site was also selected because the surrounding trees offered protection and discretion, masking the sounds of some of the noisier tests.


The interior of Cell 3 looks straight out of a sci-fi movie.

Building commenced in 1949, just as the Cold War was beginning to take hold and secrecy and paranoia were the order of the day. Things started out modestly enough, with just a few chambers or cubicles built inside larger buildings. But by 1961, Pyestock had expanded to include several large test cells big enough to accommodate supersonic jets. And the now-sprawling site continued to host covert research until it was shut down in 2000.


Pyestock Cell 4

Four main buildings made up the testing facility. Cell 4, the largest testing chamber, was constructed in 1965 at a cost of £6.5 million ($10.4 million) and was the only testing facility of its kind anywhere in the world. It was built to test Concorde and other supersonic engines and could generate wind speeds of up to 2,000 mph and match flying conditions experienced at 61,000 feet. Due to the enormous amount of energy required to power these tests, Cell 4 could only be run at night so that it didn’t overtax the local electricity grid.

A tangle of huge pipes

An earlier construction known as the Air House was connected to Cell 4 and provided the necessary suction power to simulate flight conditions. The building is described as one of the most striking at Pyestock. And its mostly glass-covered exterior features eight long, blue exhaust pipes, each one connected to an interior compressor/exhauster set mounted in two-story high concrete plinths.


Another piece of abandoned, hulking machinery

Despite its impressive size, the Air House was not able to properly meet the prodigious suction needs of the test cells once Cell 4 was built. Consequently, a ninth exhauster set was added to the facility in 1965. This multi-stage axial-flow exhauster was powered by a 6,000-horsepower synchronous motor and was used for Cell 3, Cell 3 West and Cell 4.

To get this shot of the door to Cell 3, Don Kiddick had to work up the nerve to climb down (and back up) 15 feet of cabling.

Like Cell 4, Cell 3 was also connected to the Air House; and as with the Air House, Cell 3 was built in 1961. Cell 3 was used to test the bigger engines before the construction of Cell 4. Because these tests were so noisy, most of the chamber was built underground, with the aboveground superstructure mainly used to hoist the engines down into the cell by crane. These foreboding-looking doors were added during the filming of the 2005 movie Sahara.


The site has been left to rust since 2000.

The last altitude-testing chamber to be built at Pyestock was Cell 3 West. This cell, although quite small looking on the outside, was one of the roomiest cells on site. Amazingly, Cell 3 West was able to suck in air through a large opening and support a vacuum to simulate atmospheric conditions experienced at 30,000 feet (and beyond). To complete the simulation, a cold plant chilled two giant tanks of ammonia and lowered the temperature of the cell to -22°F. Cell 3 West allowed researchers to study the effects of ice (a problem at high altitudes) on both engines and helicopter rotors, which were hung from its ceiling during the tests.

This lonely-looking dial hasn’t been pressed and turned for some time.

At the end of the 20th century, computer simulations were favored over the physical testing done at Pyestock. These simulations were cheaper, easier, and much more energy efficient. So it was that Pyestock was gradually abandoned, and its once roaring machinery was eventually silenced for good.


Water pools on the floor

“Documentation about the site was scant,” says explorer and researcher Simon Cornwell. “Photographs were largely forbidden during its lifetime. Due to its secrecy, it often merited no more than a footnote in the historic record, as only a tiny amount of information was forthcoming. And finally the physical structures themselves were threatened with demolition as… this rusting, polluted, decaying monolith to 1950s technology stood empty, unused and forgotten.”

Kiddick calls these pipes “the giant robot hand.”

Currently, Pyestock is scheduled for demolition, which has upset those who view the site as a kind of unofficial museum. The plan is to replace the test facility – regarded as one of the most important in the world – with a mega supermarket distribution center. This plan also drew more than 12,000 complaints on environmental grounds, with objectors claiming that it will ruin the area and destroy the ‘green lung’ Pyestock provides. However, the protests seem in vain and bulldozing has been scheduled to begin. No doubt many urban explorers will mourn its loss.

Sources: 1, 2, 3, 4