EXCLUSIVE: YF-23A THERMAL DESIGNER PROVIDES SOME INTERESTING DETAILS ABOUT NORTHROP ATF
By Dario Leone - Oct 14 2017010853
YF-23A thermal designer provides some interesting details about Northrop ATF
“The USAF ATF requirements did not require the ATF design to have a lot of agility. Northrop for the design of their YF-23A chose stealth over agility to meet the USAF specifications. Northrop’s aft deck design shielded the aircraft from horizontal and look up threats by hiding the exhaust. Lockheed did the opposite, they chose agility over stealth for the design of the aft section of their YF-22A,” John Shupek, designer of the YF-23A Black Widow II aft deck
The Northrop YF-23A and the Lockheed YF-22A competed against each other in the late 1980s/early 1990s in the Advanced Tactical Fighter (ATF) program.
As we have explained the YF-22A was selected as best of the two and the engineering and manufacturing development effort began in 1991 with the development contract assigned to Lockheed/Boeing.
However the YF-23A remains one of the coolest (and most intriguing) aircraft ever built.
John Shupek, a retired Aeronautical/Aerospace Engineer and now owner of Skytamer.com aviation website, was hired by Northrop in 1985, at the start of the ATF competition to do the thermal design of the back end or “aft decks” of the Northrop ATF.
YF-23A thermal designer provides some interesting details about Northrop ATF
Photo of the wheel well door of PAV-2. “I took this photo when I was the Curator of the Western Museum of Flight. At that time the Museum was located in Hawthorne, CA. This particular picture was taken circa 1995 after PAV-2 and been restored at the Western Museum of Flight. I believe that this particular callsign was placed on PAV-2 in error, since the Museum’s PAV-2 was known as the “Gray Ghost,” says John Shupek.
As Shupek tells The Aviation Geek Club, Northrop built two YF-23A prototypes. “YF-23A PAV-1 (with the Pratt & Whitney engines) was actually referred to as “Spider” and its callsign was painted on the inside of the nosewheel door. YF-23A PAV-2 (with the General Electric engines) was actually referred to as “Gray Ghost” and its callsign was painted on the inside of the nosewheel door.”
“Collectively both aircraft were referred to as the Black Widow II.” He explains “Why do I know this? I won the contest for the naming of the aircraft. Back around 1987, we had a “name the plane” contest in an obscure building referred to as “AL” which was located about a half a mile away from the main Northrop campus. This AL building is where the initial design work on the ATF program was conducted in utmost secret.”YF-23A thermal designer provides some interesting details about Northrop ATF
Shupek continues providing some interesting information about both the role he played in the YF-23A program and the “name the plane” contest. “Basically, my job was to make sure that the backend of the airplane didn’t burn off. I evaluated various types of cooling designs for the aft deck and eventually came up with the decision that “transpiration cooling” was the most effective method of cooling the aft deck of the proposed Northrop ATF design. As time passed, the initial eight airframers boiled down to 2-teams: the Lockheed team with the YF-22A (Lightning II) and the Northrop Team with the YF-23A (Black Widow II). By the way the official designations for the two aircraft were YF-22A and YF-23A, not YF-22 and YF-23 as painted on the tails. My California automobile license plate for ten years was YF23A (the correct designation). One of my AFT co-team members chose YF23 as his license plate and was really upset when he found out it was the wrong designation. After the final two teams were selected, we held an in-house competition to determine what supplier would be chosen to build the transpiration cooling tiles that were to form the aft deck of the YF-23A. We eventually chose Allison, located in Indianapolis. The Northrop chosen name for the YF-23A aircraft (Black Widow II) was not officially announced until a short time before the original photographs of PAV-1 were made public.” YF-23A thermal designer provides some interesting details about Northrop ATF
“At that time, my design work on the YF-23A was complete, and I moved on to become a Thermal Manager on the TASSAM (Tri-Service Standoff Attack Missile) subsonic stealth cruise missile program.” Shupek explains. “While on the TSSAM program circa 1989, I received a phone call from Robert R. Sandusky, Jr’s. (Robert was Northrop’s ATF Chief Engineer) secretary (Greta Kane), informing me that I had won the naming contest. The name “Black Widow II” was quite appropriate because it shared many of the same characteristics of its namesake, the Northrop P-61 “Black Widow” World War II night fighter. Both aircraft had two engines, both aircraft were extremely lethal, both aircraft were all weather aircraft, and the coup de grace for the YF-23A was that it’s RCS (Radar Cross Section) signature looked just like a spider web. The name was perfect!”YF-23A thermal designer provides some interesting details about Northrop ATF
“One day I was having lunch with Tom Rooney (former Northrop Aircraft Division vice president) in the Northrop cafeteria and I told him about my YF23A California license plate. I asked him if it was possible to get a picture of the license plate hanging off the nose of the YF-23A. Tom instantly said yes. He wanted to do this because it was a California plate, not a Missouri plate. This goes back to all of the legal problems between Northrop and McDonnell Douglas when the USAF Northrop YF-17 Cobra morphed into the USN F/A-18 Hornet. It was a bitter battle between the two companies that lasted many years. McDonnell Douglas ended up being the prime contractor, while Northrop (the initial designer of the airplane) was referred as the major subcontractor. For the ATF, these roles were reversed, thus Tom’s statement about the Missouri plate. The only reason we didn’t fly the YF-23A with the license plate hanging off the nose, was we could not find the mil-specs for a ‘License plate hanging off the nose of an airplane going over Mach 2.3.’ Well, at those speeds the string holding the license plate probably would’ve broken anyway. Needless to say Northrop ATF team was really proud of our aircraft. We absolutely knew that it was the better of the two airplanes,” he recalls.
YF-23A thermal designer provides some interesting details about Northrop ATF
Here’s a photo of John Shupek license plate on the YF-23A. “I still have the plate,” he says
About the U.S. Air Force (USAF) ATF requirements Shupek explains that “the USAF ATF requirements did not require the ATF design to have a lot of agility. The USAF was looking for a stealth fighter that would have a significant time differential between the ATF and the bandit’s discovery of the ATF. For Northrop, the aft deck of the YF-23A was one of the key stealth features of Northrop’s ATF design. Northrop chose stealth over agility to meet the USAF specifications. Northrop’s aft deck design shielded the aircraft from horizontal and look up threats by hiding the exhaust. Lockheed did the opposite, they chose agility over stealth for the design of the aft section of their YF-22A.”YF-23A thermal designer provides some interesting details about Northrop ATF
As explained By Shupek one statement, that really tells in just a few words iust how lethal the ATF designs were, was made by Norhtrop Program Manager, Dell Jacobs, circa 1986 for a Wright-Patterson briefing about the ATF program. “The ATF will have the same tactical advantage over the F-15 that the F-15 has over the Goodyear blimp. Believe it or not, that’s a true statement. The statement applies to both of the ATF designs. The first sign that a MiG pilot would have that an ATF was in the area, would be its engine blowing up from a missile hit!”
“The real reason we (Northrop) lost the program was that Lockheed had no new fighter programs at that time, while Northrop had the F/A-18E/F and the B-2.” Shupek reveals. “It was in the national interest of the U.S. to keep Lockheed alive as an airframer. We were told through unofficial channels after the competition, that our design actually met the specs better than the Lockheed design. Believe it or not, Northrop actually won by losing the ATF competition. The Soviet threat that the ATF aircraft were designed for evaporated in 1989 as Humpty Dumpty fell off the Berlin Wall and all the Kremlin’s resources and the Kremlin’s men couldn’t put Humpty Dumpty back together again. After Humpty Dumpty, the U.S Congress reduced AFT funding thus forcing the USAF to reduce the number of F-22s that were to be purchased. Meanwhile the Boeing/Northrop-Grumman team kept on building the F/A-18E/F/G’s and everybody seemed to want some of these aircraft for their tarmac.”YF-23A thermal designer provides some interesting details about Northrop ATF
During his 36-year career Shupek was also part of the Pratt & Whitney (P&W) jet engine design team for the CIA/USAF’s Lockheed A-12/SR-71A “Oxcart/Blackbird” engines (J58/JT11D-20), as he recalls. “In my earlier years, as a brand new engineer fresh out of the “Cookie Jar”, I worked at Pratt & Whitney in Florida on the SR-71A Blackbird engines. My job was to design the cooling for the first stage turbine blades and vanes. Again, like the YF-23A, it was my job to make sure that the JT11D first stage turbine blades and vanes didn’t burn up and cause a big boom. Keep in mind, during this era, our computers were in their infancy. Both Lockheed and Pratt & Whitney engineers used slide rules for the majority of their calculations. At Pratt & Whitney, we had an IBM 1600 “16K” card reader computer, and an IBM 360 mainframe computer with an amazing “360K” of computing power. My God, who could ever need more computing power than that!”YF-23A thermal designer provides some interesting details about Northrop ATF
Going back to the YF-23A program, Shupek says that testing of the ATF aft deck tiles was made at P&W’s FRDC (Florida Research and Development Center) behind Pratt’s YF119 AFT test engines. “We tested several designs behind the engines and found out that the “transpiration cooled” aft deck tile design did the job. I still remember the exact moment when I called Bob Sandusky back in California and all I said was “Bob, we have an airplane!” Needless to say, Sandusky was extremely pleased and we continued on from there. If the tile design had not worked, we most likely would have had to redesign the back end of the aircraft, which most likely would’ve increased the RCS signature of the aircraft, thus making it less stealthy.”YF-23A thermal designer provides some interesting details about Northrop ATF
Shupek adds some interesting details about the testing of the aft deck tiles. “When we did the testing of the aft deck tiles down at Pratt, the YF119 was in the full afterburner mode. This might help you to imagine what it looked like. Imagine a 50 foot long exhaust flame plume coming out of the backend of the engine with seven or eight shock diamonds visible in the exhaust plume. Of course the sound that the engines produced was extreme. For example, when I worked on the Blackbird engines, I lived in Jupiter, Florida which was about 20 miles away from the P&W plant, and the test cells were an additional 4-5 miles back into the Everglades. At night, 25 miles away, we could hear the SR-71A engines being tested.”
YF-23A thermal designer provides some interesting details about Northrop ATF
A piicture of the aft deck tiles taken by John Shupek at the Western Museum of Flight, during his tenure as the curator.
“Time marched on, and I eventually retired from Northrop-Grumman in 2000 with the title of Northrop Grumman Program Director F/A-18E/F Super Hornet,” Shupek concludes. “Working for Northrop was one of the “funnest” times of my life. Believe it or not, it was one of those jobs that you looked forward to going to work every day just for the adventure of it. Who could ask for a better job?”YF-23A thermal designer provides some interesting details about Northrop ATF
Photo Courtesy of John Shupek
Additional images: U.S. Air Force
www.c-span.org
Tony chong explicitely label the EMD proposal as starting point for the final version. Besides, not only one version of the F-23 was studied at the time depending on evolving requirements within the ATF program. There were post EMD configurations studied but so far we haven't been able to see any of them.
