You know what a B-17 looks like. Four radial engines. The towering tail fin. Glass nose. Heavy-bomber Americana, stamped onto a thousand black-and-white photographs of the daylight raids over Germany. Now picture one with a fifth engine bolted to its nose — usually a big turboprop, mounted where the Plexiglas bombardier station used to be. For a while, a jet hung beneath it.
That happened. Curtiss-Wright Corporation flew exactly this aircraft for nineteen years, from 1947 to 1966, out of a small airport in Caldwell, New Jersey, testing every new piston, turboprop, and jet engine the company built. The bomber was officially designated EB-17G, later JB-17G, but most of the people who flew it just called it "the testbed."
A B-17 Flying Fortress with a fifth engine bolted onto its nose. Via @worldwaraviationgroup on Instagram
Quick Facts
Aircraft: Boeing B-17G Flying Fortress (modified by Curtiss-Wright)
Operator: Curtiss-Wright Corporation, Caldwell-Wright Airport, New Jersey
Operational period: 1947-1966
Modification: Fifth engine mounted in nose position, replacing bombardier glass
Engines tested: Wright XT35 turboprop, Wright R-3350 (including the turbo-compound), Wright J65 turbojet, later a T64 turboprop
Purpose: In-flight testing of new piston, turboprop, and jet powerplants
Crew: 4-6 (pilot, co-pilot, flight engineer, test engineer, observer)
Why a B-17?
By 1947 the B-17 was obsolete. The Air Force was retiring them by the hundred and selling them as surplus to anyone with a hangar and a dollar. Curtiss-Wright leased one, B-17G serial 44-85813, in October 1945, had Boeing convert it at Wichita, based it at Caldwell, New Jersey, and asked: what if we used this as a flying engine test stand?
The B-17 had three things going for it. It was huge — long enough to mount a substantial engine on the nose without overloading the centre of gravity. It was already built to handle the asymmetric thrust of four wing-mounted engines, so a fifth engine in front did not destabilise it. And with the war over, surplus bombers were easy to come by. Curtiss-Wright later bought the aircraft outright, in August 1957, and registered it N6694C.
A Fifth Engine, A New Job
Curtiss-Wright's engineers stripped out the bombardier station, the chin turret, and most of the forward fuselage equipment. In its place they bolted a structural test mount sized for almost any contemporary engine. The aircraft's four original radial engines stayed in place, providing reliable propulsion at all times. The fifth engine — the one being tested — could be started, run at full power, instrumented, and shut down in flight without ever putting the aircraft itself at risk.
This mattered. Before the testbed, every new aircraft engine had to fly on a prototype aircraft, and prototype aircraft crashed. The B-17 testbed gave Curtiss-Wright a flying laboratory where engineers could log thousands of hours on a new engine before it ever entered a production aircraft.
Engines That Flew on the Testbed
The Wright XT35 turboprop came first. It was intended above all for Boeing’s early XB-52 design, and the B-17 began flying with it in the nose in September 1947. The Air Force switched the B-52 to the Pratt & Whitney J57 jet in October 1948, and the T35 was cancelled in March 1949.
The Wright J65 turbojet, Curtiss-Wright’s licence-built version of the British Armstrong Siddeley Sapphire, flew on the B-17 in 1950–51. Unlike the turboprops, it was not fitted in the nose itself but slung underneath it. The J65 went on to power the F-84F Thunderstreak, the A-4 Skyhawk, the B-57 Canberra and the F-11 Tiger.
The big Wright R-3350 radial, including its turbo-compound version, also flew in the nose, and a later R-3350 was used for propeller research. By the mid-1960s the mount carried a T64 turboprop with a six-blade propeller.
The aircraft was, in effect, a flying spec sheet: new engines could be run, measured and shut down in real flight, while four tried-and-tested Cyclones kept the bomber in the air.
From Test Bed to Fire Bomber, and Back
Curtiss-Wright sold the aircraft to Ewing Aviation on 1 December 1966. It went on to Black Hills Aviation in Spearfish, South Dakota, which rebuilt it with a standard B-17 nose taken from another airframe and flew it as air tanker C12. On 16 April 1980 it crashed on take-off for a firebombing sortie at Bear Pen, North Carolina. By then Curtiss-Wright had long since lost the big engine contracts to Pratt & Whitney and General Electric.
The story does not end there. The wreck was not scrapped. It passed to restorer Tom Reilly in 1985 and gave up parts to help rebuild another B-17, and the airframe is now being restored to flying condition as “Champaign Lady”, registered N3154S, at the Champaign Aviation Museum in Urbana, Ohio. About 45 B-17s survive in complete form today, and only around half a dozen are airworthy. None of them still carries a fifth engine.
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Updated 12 October 2026: we corrected the engine list (the TJ-32 flew on a B-29, not this B-17), the XT35’s intended aircraft, how the J65 was mounted, and the aircraft’s fate. The test bed was not lost for good in 1980: it survives and is being restored.
Sources: Warbird Registry (B-17G 44-85813 history); 1000 Aircraft Photos; Aircraft Engine Historical Society, Wright T35; General Aviation News (September 2021); Aero Vintage; b17flyingfortress.de; Wikipedia, List of Boeing B-17 Flying Fortress variants, Wright J65 and List of surviving Boeing B-17 Flying Fortresses; Smithsonian National Air and Space Museum.
Related Questions
Why did a B-17 have a fifth engine on its nose?
Curtiss-Wright bolted a fifth engine to a B-17’s nose to use the bomber as a flying engine test stand. From 1947 to 1966, the company mounted experimental piston, turboprop, and jet engines where the bombardier’s glass nose had been, testing each new powerplant in real flight conditions out of Caldwell, New Jersey.
What was the B-17 engine testbed designated?
The modified aircraft was officially designated EB-17G, and later JB-17G, though the crews who flew it simply called it "the testbed." Operated by Curtiss-Wright, it carried a fifth engine in its nose for nearly two decades - a quiet research role far removed from B-17 combat missions like the Schweinfurt raid.
Why was a B-17 chosen as an engine testbed?
The B-17 was ideal because it was big, cheap, and docile. After 1945 the bomber was obsolete and surplus. Its long airframe could carry a substantial nose-mounted engine without upsetting the centre of gravity, and its four existing engines kept it flying safely even if the experimental test engine failed.
Which engines were tested on the B-17 testbed?
Curtiss-Wright tested a range of its powerplants on the B-17’s nose mount, including the Wright R-3350 piston engine, the Wright J65 turbojet, and the Wright XT35 turboprop. The arrangement let engineers evaluate new piston, turboprop, and jet engines in genuine flight conditions.
How long did the B-17 engine testbed operate?
The Curtiss-Wright B-17 testbed flew for nineteen years, from 1947 to 1966, out of Caldwell-Wright Airport in New Jersey. It carried a crew of four to six, including pilots and test engineers, evaluating successive generations of engines during a period of rapid change captured in the broader history of aviation.
The B-17 “Test Bed” is being restored to its original bomber configuration as the Champlain Lady by the Champlain Aviation Museum https://www.champaignaviationmuseum.org/b17g