Northrop TACIT BLUE

flateric said:
well, everyone, go for search of this pdf (or ppt) - we have a second confirmation that it was aviable on the net
keywords Dick, Rishard, Thomas, Tacit Blue, Northrop

I've been trying to find this. The closet I've gotten is here; http://www.gbv.de/dms/tib-ub-hannover/240761235.pdf

Tacit Blue Flight Test Report
Ken Dyson (F)
Richard G Thomas (F), Northrop Grumman
Russ Easter Calspan
Dan Vanderhorst (M)
(Paper Not Available For Publication)
 

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yasotay said:
USAF would never have owned more than one. It looks like a loaf of bread with wings. They DO have an image to uphold. ;D

Interesting how similar the Northrop AGM-137 TSSAM was to this in layout.
Basically, the same fuselage, flipped over and scaled-down. TSSAM had different tail surfaces, though, and for carry (and container-launch for BGM-137B), all the surfaces folded up into a nice, compact all-aspect LO package. If nothing else, a lot of the same people were involved in both.
 
The final phase of TACIT BLUE follow-on testing involved "first flight with modified landing gear, first flight with internal bays installed, first flight with bay doors open, [and] separation tests." Bear in mind that this was after the LPI radar test had been completed, and the airplane temporarily mothballed. Feel free to draw your own conclusions.
 

Bondo Gave The Secret Tacit Blue Demonstrator Jet Its Smooth Stealthy Skin​


Veteran Northrop engineer recollects his time on the top-secret Tacit Blue program, including some of its oddest quirks.


By Brett Tingley and Tyler Rogoway
February 20, 2022

In the late 1970s, the Pentagon saw a need for a new class of battlefield surveillance aircraft that could penetrate into denied airspace and collect intelligence in real-time for long periods by using a new technology that was beginning to emerge known as stealth. With this in mind, the U.S. Air Force and the Defense Advanced Research Projects Agency approached the Northrop Corporation, which had some experience with stealth technology already, to build a reconnaissance aircraft built around an advanced radar system. The resulting prototype aircraft was known as Tacit Blue, now regarded by the Air Force as one of the most successful technology demonstrators ever funded.

To shed light on the history of the Tacit Blue Project, the Western Museum of Flight in Torrance, California hosted veteran Northrop aerospace engineer Don Murray last year. The museum’s director introduced Murray as “a key player in the development of highly stealthy technology” and “widely recognized among the pioneers of stealth.”[...]

[...]Murray was assigned to be a second shift supervisor for the Tacit Blue project, which grew out of an Air Force and Defense Advanced Research Projects Agency (DARPA) initiative known as the Battlefield Surveillance Aircraft-Experimental (BSAX) program. That program was aimed at producing a technology demonstrator aircraft that combined the battlefield survivability aspects of a low-observable stealth aircraft with a low probability of intercept (LPI) radar and data-link suite[...]

[...]When he joined the program, the basic airframe had been completed and assembled. Murray explained that the wings and fuselage of the demonstrator were constructed out of a standard aluminum alloy, while the radar-sensitive empennage and leading edges of the wings and fuselage/chines being built from a “proprietary Northrop composite material” that was key to the aircraft's stealthiness.[...]

[...]The program encountered few problems during pre-flight development, but Murray explained how the team had difficulty “attaining the smoothness and curvature on the fuselage to satisfy low observable requirements.” To remedy this, Northrop engineers turned to Bondo, a plastic-based auto body filler commonly found in auto parts stores.[...]

[...]The program worked under strict sight sensitivity controls, meaning the AP-1 demonstrator had to be hidden from view when not performing tests that required it to be moved outdoors at Area 51. “The program was highly classified,” Murray said. “The vehicle was sight-sensitive.[...]

[...]To protect the aircraft from being seen, Murray said that most of the ground testing was performed inside a hangar. “We even did low- and high-power engine runs inside the hangar.[...]

[...]During these ground tests, the team discovered that it was impossible to start the AP-1’s Garrett ATF3 engines without starting them both at the same time. Because both turbofan jet engines shared a common intake without a splitter and were mounted side-by-side, any attempt to start the engines one at a time would fail due to the first engine “hogging up all the air,” Murray said. [...]

[...]To remedy this, Murray’s team developed what they called the “Almost Simultaneous Start, with the appropriate acronym,” according to the veteran engineer. “We’d get the first engine cranking, and before it lit off, we’d crank the second engine. So they more or less lit off and spooled up to idle speed at the same time.”[...]

[...]Once these ground tests were completed, the Tacit Blue flight test program began. Missions were conducted at Area 51 from February 1982 until June 1985 and consisted of over 140 sorties totaling 250 hours.[...]

[...]Now-retired Lt. Gen. George K. Muellner, who served as principal deputy assistant secretary of the Air Force for Acquisition, stated at the Tacit Blue’s unveiling that the program “turned into a test-bed because its low-observable technologies proved to be more valuable than its [mission] contribution.[...]

[...]Still, there were concerns that an operational version of the Whale would be limited to nighttime missions due to its visual signature. For this specific role of tracking large armored columns and Soviet troop movements, it was also an issue that an operational but still secret Tacit Blue offspring's intel would have been so good that anyone who saw it would wonder where it came from and the asset's existence would have been realized fairly quickly. In other words, it was too effective to regularly use and integrate into standard operations while maintaining any modicum of secrecy. [...]

[...]Ultimately, Tacit Blue remains one of the most ambitious and influential aircraft development programs in history, proving that even a 'Whale' sporting a giant radar can take to the skies and remain there undetected.[...]

View: https://youtu.be/gAPw5FEpYBw?si=DezP7wysch3mMsJz
 
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some inlet details get into USAFM XB-70 fly-over video
 

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Were other demonstrators flown for the duration that Tacit Blue was?

“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.”

Citing another source.
“One issue was that the data it gathered was so good, those not read into the program would have wondered where it was coming from. While the B-2 was so big it would have to be disclosed, an operational fleet of Tacit Blue aircraft wouldn't have been. But how do you use it without giving away that it exists? This was an early debate regarding a potential production aircraft's concept of operations.“

What I’m getting at. I know enough that it seemed pretty rough as things like bondo being used. It just seems like this was such a powerful tool on the other hand. Was Tacit Blue used somewhat operationally or outside of the US? Forgive my ignorance towards this. It’s something I have always been curious about. There seems to be more unknown about Tacit than is known despite its declassification.
 
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Were other demonstrators flown for the duration that Tacit Blue was?

“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.”

Citing another source.
“One issue was that the data it gathered was so good, those not read into the program would have wondered where it was coming from. While the B-2 was so big it would have to be disclosed, an operational fleet of Tacit Blue aircraft wouldn't have been. But how do you use it without giving away that it exists? This was an early debate regarding a potential production aircraft's concept of operations.“

What I’m getting at. I know enough that it seemed pretty rough as things like bondo being used. It just seems like this was such a powerful tool on the other hand. Was Tacit Blue used somewhat operationally or outside of the US? Forgive my ignorance towards this. It’s something I have always been curious about. There seems to be more unknown about Tacit than is known despite its declassification.

No. TACIT BLUE was strictly used for testing over the Nevada Test and Training Range. It was a very productive technology demonstration program. Results were passed on to the B-2, E-8 Joint STARS, and AGM-137 TSSAM development efforts.
 
I was never on the Tacit Blue program but I had worked with Dick Thomas elsewhere and Dick stated to look out the side windows, you had to stretch quite a bit to see out, very wide cockpit. I have seen the aircraft close-up at the USAF museum along with the two other programs I was on, B-2 and YF-23.
 
Dan Vanderhorst presented on behalf of Dick Thomas.

aero-engineer
Presentation title was 'Tacit Blue first flight'
SETP Flight Test Safety Workshop 2003

I’ve asked around, I was told that the 1996 paper was not published in the conference proceedings. SETP was not able to provide a copy.
 
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I can't help but wonder if the pilots felt like they were flying a bus with all that windscreen. ;)
 
One of the goofiest looking planes ever to fly...

They did all that LO work and then realized that as soon as they used the radar data people would wonder where it came from. *facepalm* But that turned into the E-8 JSTARS aircraft used in Desert Storm.

These days, I suspect that it'd be a drone. No reason to build a man-rated aircraft then, and you could maybe build it smaller (not sure how much of the airframe size was driven by the radar arrays).
 
At least the radar from the Tacit Blue got used in the E-8 JSTARS aircraft, that was one positive outcome from the program and we all saw just how good it was when they showed the Iraqi troops fleeing from Kuwait.
 

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