You are correct!
Here is some more info on the two 5 engined B-17's.
The B-17G (SN 44-85734)[2] did not see combat in World War II, and was originally sold on June 25, 1947 as scrap to Esperado Mining Co. of Altus, OK, it sold again later that year to Pratt & Whitney for $2,700. Pratt & Whitney operated the B-17 from November 19, 1947 to 1967 as a heavily modified test bed for their P&W T34 turboprop engine under the registration N-5111N [3]. Similar to registration numbers 44-85747 and 44-85813 [4], it became a “5-engine aircraft”, having the powerful prototype engine mounted on the nose. The aircraft was flown “single-engine,” with all four radial engines feathered during test flights. Following the test flights, it was donated to the Connecticut Aeronautical Historic Association, where a tornado on October 3, 1979 blew another aircraft onto the B-17’s mid-section, breaking the fuselage.
B-17 44-85734 was eventually purchased by aviation enthusiast Don Brooks who formed the Liberty Foundation to exhibit the plane as the "Liberty Belle." Restoration began in 1992 with parts from another damaged B-17 (44-85813). Restoration by Tom Reilly and company/Flying Tigers Warbird Restoration Museum (aka "Bombertown USA") located at that time at Kissimmee Gateway field Kissimmee, FL. Evidence of the rebuild may be seen in very professional stringer splices aft of the waist gun positions. She returned to the air December 8 2004, and has been touring the air show circuit since then. The Liberty Foundation also planned a historic overseas tour in July 2008 along the northern ferry route to England.
12/31/2009. After WW II, two Vega-built B-17Gs were drastically modified as flying test beds for engines, so a revised Boeing model number of 299Z was assigned to these airframes. The military features were removed, the pilot's compartment was moved aft, and the nose was modified to accommodate the test engine. Each turbo-prop test engine was more powerful than all four standard engines operating together.
The first, s/n 44-85813, was leased to Curtiss-Wright from October 1945, being converted by Boeing in 1946, after which it was designated EB-17G by the USAAC. Test flights with the XT-35 turboprop started in September 1947, tests with the J65 Sapphire jet engine started in 1951. The designation was changed to JB-17G in 1956, while the aircraft was sold to Curtiss-Wright on August 30, 1957, registered as N6694C. Thereafter an R-3350 radial engine was fitted in the nose for propeller research, last engine tested was the T-64G turbine-prop.
Curtiss-Wright sold the aircraft and subsequently it was registered to Ewing Aviation from December 1, 1966, Ewing-Kolb Aircraft from August 15, 1969, Arnold Kolb/Black Hills Aviation from July 30, 1970. The latter had the aircraft fitted with a standard forward fuselage, that was taken from s/n 44-83316, and used it as an aerial tanker, listed as number C12; it crashed near Bear Pen, North Carolina on April 16, 1980.
The wreckage was bought by Tom Reilly Vintage Aircraft in 1985, and parts were used to restore 44-85734/N5111N (mentioned below). The remaining wreckage was obtained for another B-17 project, and is presently registered as N3154S to Tech II, being rebuilt to airworthiness using parts of B-17s, s/n 44-85813, 44-83316, 44-83525, and 44-83722.
The pictured second engine test bed is described in photo 6021.
"JB-17G 1945 = Civil and USAF test-bed for an added 6000hp P&W XT34 "Turbo-Wasp," Wright XT-35, Wright R-3350, and Allison T-56 POP: 3 [N5111N, 44-85747, x]. While results were encouraging, the armistice and dawn of the jet age curbed the project."
"JB-17G-VE B-17G s/n 44-85813. Flying test aircraft. Civil registered N6694C and later N5111N "
"This particular B-17 was modified by Boeing for Pratt & Whitney to become a postwar engine testbed. Operated as N5111N, the airframe was substantially modified to accept a large radial engine in the nose. The cockpit was moved several feet aft and the fuselage was extensively reskinned for additional strength. Pratt & Whitney donated the airplane to a museum at Hartford, Connecticut, where it was displayed outdoors for a number of years. In 1979, however, it was nearly destroyed by a tornado that swept through the museum complex"
"Tight Lines!"
Wes
P.S.: The remaining parts are being used for a B-17 restoration in Urbana, Ohio at Grimes Field. Took several pics of it during the Doolittle Raiders Reunion last month.
Purchased by Tech II, Inc./Shiffer Family. Being Restored at Grimes Airport in Urbana, OH