| Tacit Blue | |
|---|---|
 Northrop Tacit Blue in flight | |
| General information | |
| Type | Stealth demonstrator |
| Manufacturer | Northrop Corporation |
| Status | Retired |
| Primary user | United States Air Force |
| Number built | 1 |
| History | |
| First flight | February 5, 1982 |
| Retired | 1985 |
TheNorthrop Tacit Blue is atechnology demonstrator aircraft created to demonstrate that a low-observablestealthsurveillance aircraft with alow-probability-of-intercept radar (LPIR) and other sensors could operate close to the forward line of battle with a high degree of survivability.
Unveiled by the U.S. Air Force on 30 April 1996, theTacit Blue Technology Demonstration Program was designed to prove that such an aircraft could continuously monitor the ground situation deep behind the battlefield and providetargeting information inreal time to a groundcommand center.
In December 1976, DARPA and the U.S. Air Force initiated theBattlefield Surveillance Aircraft-Experimental (BSAX) program, which was part of a larger Air Force program calledPave Mover. The BSAX program's goal was to develop an efficientstealthreconnaissance aircraft with alow probability of intercept radar and other sensors that could operate close to theforward line of battle with a high degree ofsurvivability.
Tacit Blue represented the "black" component in the larger "Assault Breaker" program, which intended to validate the concept of massed standoff attacks on advancing armored formations usingsmart munitions. The Pave Mover radar demonstrators provided the non-stealth portion of the program'stargeting system, whereas Tacit Blue was intended to demonstrate a similar but stealth capability, while validating a number of innovativestealth technology advances.[1]
The radar sensor technology developed for Tacit Blue evolved into the radar that was used by theE-8 Joint STARS aircraft.[2]
Tacit Blue was given the cover designation of "YF-117D" by the Air Force.[3][4]
Tacit Blue, nicknamed "the whale" (and sometimes also called an "alien school bus" for its only slightly rounded-off rectangular shape),[8] featured a straighttapered wing with aV-tail mounted on an oversized fuselage with a curved shape. It was the first stealth aircraft to feature curved surfaces forradar cross-section reduction.[9] Northrop would use thisstealth technology on theB-2 bomber. A singleflush inlet on the top of the fuselage provided air to twomedium-bypass turbofan engines. Tacit Blue employed a quadruply redundant digitalfly-by-wire flight control system to help stabilize the aircraft about its longitudinal and directional axes.
The aircraft made its first successful flight on February 5, 1982, inArea 51, atGroom Lake, Nevada, flown by Northrop test pilotRichard G. Thomas.[7] The aircraft subsequently logged 135 flights over a three-year period. The aircraft often flew three to four flights weekly and several times flew more than once a day.
Another Tacit Blue test pilot, Ken Dyson, told CNN in 2014 that Northrop had manufactured additional major components for the jet, which amounted to half of a second plane. "If we lost one, we could have a second one up and flying in short order," Dyson said.[10]
After reaching about 250 flight hours, the aircraft was placed in storage in 1985. In 1996, after Tacit Blue was declassified, it was placed on display at theNational Museum of the United States Air Force atWright-Patterson Air Force Base, nearDayton, Ohio and has been on display in the fourth hangar at the museum since June 2016.[11]
Data from theNational Museum of the United States Air Force and theDepartment of Defense
General characteristics
Performance
Aircraft of comparable role, configuration, and era
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