Known as technology demonstrators, these pioneering stealth aircraft remained top secret for years after their final flights before being declassified. Categorised as black projects and operating from the secret Groom Lake test site in Nevada, popularly known as Area 51, the three groundbreaking designs below tested low observable technologies and proved that stealth aircraft could operate deep behind enemy lines with a high degree of survivability. Together, they helped return the element of surprise to air warfare.
From 1977 to 1979, the revolutionary Lockheed Have Blue tested a new form of low observable technology known as faceting. Rather than smooth aerodynamic lines, Have Blue adopted an angular, faceted shape to deflect electromagnetic waves and lower its radar signature. Aided by a fly-by-wire control system to rectify its aerodynamic instability, Have Blue paved the way for an aircraft that changed the face of modern warfare – the F-117A Nighthawk, known as the Stealth Fighter.
(Image: left & right by U.S. Federal Government, public domain)
Despite the exotic technologies they seek to perfect, technology demonstrators are often relatively cheap to manufacture. Built by Lockheed’s shadowy Skunk Works, Have Blue utilised off-the-shelf components including an adapted F-16 fly-by-wire system. Two demonstrators were built, XST-1 and XST-2, both of which crashed during development with their pilot’s ejecting. Even so, the programme was considered a resounding success.
As is often the case with top secret technology demonstrators, the wreckage of the two Have Blue aircraft was buried within the Nellis Test Range. One was reportedly buried at the Groom Lake site just south of the hangar complex. Lockheed engineers have since searched for the buried Have Blue with a view to restoring it for display purposes, but despite their best efforts have been unable to locate the wrecked aircraft.
Arguably one of the strangest looking planes ever built, the Northrop Tacit Blue was a technology demonstrator designed to show that a stealth surveillance aircraft could operate deep behind enemy lines while feeding real-time targeting information to a ground command centre. Nicknamed “the whale”, Tacit Blue first flew in 1982 and retired in 1985 after logging 135 flights.
(Images: top, bottom, U.S. Air Force, public domain)
Stealth and sensor technologies tested on Tacit Blue have been integrated into current operational aircraft. After retirement in 1985, the one-of-a-kind technology demonstrator was placed in storage at a top secret facility at Groom Lake known as Dyson’s Dock, before it was finally revealed to the public in 1996. Tacit Blue is now on display at the National Museum of the United States Air Force at Wright Patterson Air Force Base in Ohio.
Like Have Blue and Tacit Blue before it, the Boeing Bird of Prey was a black project tested at the top secret Groom Lake facility. Developed by the McDonnell Douglas Phantom Works (which later became part of Boeing), only one Bird of Prey technology demonstrator was built, taking to the air in 1996. Named after a spaceship from Star Trek, the aircraft made 39 flights before the programme’s conclusion in 1999, helping develop technologies since used on Boeing’s X-45 and X-47 unmanned combat air vehicles.
Funded entirely by the company, Bird of Prey was a relatively low cost programme at $67 million, utilising off-the-shelf components. Despite its radical appearance, the aircraft was aerodynamically stable enough to use manual hydraulic controls rather than fly-by-wire, reducing both development time and cost. It is also rumoured to have tested “active camouflage”, changing colour and luminosity to match its surroundings.
After the programme’s conclusion, Bird of Prey was stored in Dyson’s Dock for three years before being declassified in October 2002. While it’s now on display at the National Museum of the United States Air Force, other occupants of the enigmatic Dyson’s Docks remain firmly under wraps. One such rumoured technology demonstrator thought to reside in Dyson’s Dock to this day is a manned low observable flying wing design known as Sneaky Pete. Whether it will see the light of day any time soon, however, is reportedly doubtful.