Canada Aviation and Space Museum
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CANADA AVIATION AND SPACE MUSEUM BOEING MODEL 720B PRATT & WHITNEY CANADA FLYING EXPERIMENTAL TEST BED REGISTRATION C-FETB Introduction The practical era of jet-age passenger transport aircraft officially dawned when the British de Havilland Company D.H.106 Comet made its premiere flight to great acclaim from the Hatfield, Hertfordshire aerodrome in England on 27 July 1949. Catering to British and mid to long-range routes to European, Middle Eastern and overseas destinations, the Comet series of airliners carried their passengers aloft in luxurious opulence for more than twenty years. Military and test derivatives followed suit and these continued flying for many decades, including two Comets for the Royal Canadian Air Force (RCAF). Just 14 days later, across the vast Atlantic Ocean, in the small town of Malton, Ontario, Canada, a new aviation company called Avro Canada successfully accomplished the same task with much less fanfare and accolades. Avro sent its small, medium-range, turbo-jet transport, called the C-102 Jetliner, aloft for its first flight, inaugurating the dreamed potential for such a unique travel experience for the public on the North American continent. United States Air Force personnel found the aircraft favourable when they tried it out on flights at Wright Field, Ohio in March 1951. However, this Canadian dream didn’t last for long. The modestly successful Comet-series didn’t shine as brightly as its popular name when a series of tragic, fatal accidents to production civil aircraft nearly snuffed out its very existence. Following design rectification’s, the Royal Air Force continued to employ Comets in versatile roles, such as modifying the design into the Nimrod. Success of the sole C-102 Jetliner was hampered, then denied, by lacklustre marketing efforts and, as is all-too-often in Canada, a long-time pernicious lack of interest, knowledge and funding by the government for nearly all new things with any kind of aviation moniker attached to it. It wasn’t for another, long five years before a new smoky and thunderous roaring of powerful jet engines on a revolutionary jet transport sounded again, this time coming from the ever-imaginative and growing product lineage emerging from the famed Boeing Airplane Company of Seattle, Washington. On 15 July 1954, the first example of a soon-to-be very long line of jet engine powered passenger, cargo, and military transport derivatives, factually called the Boeing Model 367-80, known simply as “Dash 80”, flew. The model lineage from the premiere “Dash 80” aircraft to the last of the modern-era versions of this Boeing transport-series is long and varied. One of those ‘varied’ examples is a specific Boeing 720B (Serial Number 177) that spent many years earning a living hauling paying passengers across the skies under numerous commercial banners. Later, it was chosen and heavily modified as a dedicated inflight test platform for short-term testing of many experimental and production jet engines by Pratt & Whitney Canada (P&WC). This last surviving example of the Boeing Model 720B series ended its engine-testing career then retired to the renowned CASM collection for an honourable static public display in Trenton. Cover Photo Caption: The Boeing 720B Flying Experimental Engine Test Bed (C-FETB) “Red” of P&WC takes off on 29 September 2009, from the Saint-Hubert airport, east of Montreal, with a nose-mounted PT6 turboprop engine to test in flight. (via Mario Mattarelli) Boeing Model 367-80 “Dash-80”, Model 707-Series Prototype The post-war period was a unique time in aviation when nearly all aircraft manufacturers were kept very busy trying to come up with new, or revolutionary and experimental designs to offer potential military and commercial customers. Interestingly, in 1946, one of these new revolutionary and experimental designs came from the talented engineering mindset at the Douglas Aircraft Company in Santa Monica, California. This aircraft, designated as the XB-43, was powered by two General Electric J35 turbojet engines and was to potentially take over some tasks of the Boeing B-29 Superfortress bomber. This medium-attack bomber historically became the first jet-powered bomber to fly in the United States, but it was ultimately destined to never go into production as better ideas were on other manufacturers drafting boards. Using a pugilistic frame of reference of the time, in one corner was Boeing, principally the builder of multi- engine jet-powered bombers for the US military like the B-47 Stratojet and later B-52 Stratofortress. As well, Boeing produced piston-powered transports like the military C-97 and KC-97 aerial refueling tanker, and the Model 377 Stratocruiser commercial transport. In the opposite corner was the rival, Douglas, that produced so many piston-powered airliners like the DC-3 and its successors; the DC-4, DC–6 and DC-7 types for the civil market, and C-54, C-124 and C-133 cargo and personnel transports for the US military. In June 1955, Douglas announced its intention to develop a lengthy and spacious new turbojet-powered airliner, designated as the DC-8, to supercede the older DC-7. Now, the fight was on. To help in the push for potential sales, the “Dash 80” interior was modified reflecting a combination of a passenger (seat rows on the right side), and cargo space (along the left) configured interior to satisfy the proponents of each. In the US Tactical Air Command (TAC) and the Strategic Air Command (SAC) direct aerial refueling support for the fleets of fast fighter aircraft types and the high-flying B-47 and B-52 jet bombers consisted of only the relatively slow piston-engined aircraft like the KC-97 tanker with its Boeing-developed flight refueling boom. There was a lot of “make do” and tense moments where flight crews of the two aircraft were forced to constantly adjust their handling of the fast (jet) and slow (prop) aircraft boom-joined combinations to avoid accidents. The later addition of General Electric J47 turbojets slung in pods at the wingtips of the KC-97s only marginally helped. This was never an ideal compromise. What was truly needed was a jet-powered transport, tanker, and passenger combination all-in-one design, however both Boeing and the military were both seriously hurting for funds. This design attempt was to be a big gamble. Again, the “Dash-80” was reconfigured, this time incorporating a retractable dummy refueling boom under the rear fuselage, and performed rendezvous and simulated inflight refueling to prove the concept sound. During the service trials of Boeing’s civil Stratocruiser, feasibility studies of a proposed Model 367 Pratt & Whitney J57 jet-powered version towards use as a possible passenger airliner began in earnest. The proposed addition of swept wings and tail, derived from the successful B-47 strategic bomber, to the design, would go a long way towards enhancing its performance. In 1955, after losing a commercial aircraft order to the Douglas Aircraft produced DC-8 airliner, that had a longer fuselage to accommodate more fare-paying passengers, Boeing started a production line of its own civil aircraft model, the 707-120. By the final bell, years later, Douglas merged with McDonnell; then Boeing took over its long time rival. The Model 367-80 Lineage It all began as the Model 367-80 with “Boeing 707” emblazoned upon the tail as the 707 prototype. Next came the official Model 707 civil airliner version that sold in great numbers around the world. The Model 717 became the military’s C-135, KC-135, EC-135, VC-137 et al series. The Model 720 series was a new design, basically, at first glance, seeming to be just a stubbier and lighter, short to medium-range version of the basic Boeing Model 707 commercial aircraft. Surrounded by workers, VIPs and press personnel, the yellow and chocolate-coloured Model 367-80, Boeing 707 prototype (N70700), is being officially rolled out from Boeing’s Renton, Washington plant on 15 May 1954. (Bill Upton Collection) Canadian and American Flying Engine Test Beds (FETB) In the 1950s and 1960s, some large multi-engined aircraft were modified and employed as experimental flying engine test beds. Ground-based static test runs of engines only produced a baseline set of results regarding engine operation and thrust when performed in a contractor’s dedicated test facility. Dynamic tests of an engine mounted on an aircraft while flying would produce a more definitive set of interactive measurements with the test aircraft, which would still have its original installed engines available and operating for standard onboard instruments and in case of an emergency or other potential mishap. Avro (Victory Aircraft) Lancaster Mk X The Lancaster Orenda test bed FM 209. (CASM Collection) The premiere flying engine test bed in Canada was a modified Canadian-made Lancaster Mk X, RCAF FM 209, loaned in 1950 to Avro Canada. It was utilized to test the new Orenda jet engines destined for the definitive versions of the Avro CF-100 Canuck (Mk 2 to Mk 5) interceptors and Canadair CL-13 (F-86) Sabre (Mk 5 & Mk 6) fighters for the RCAF. Two of these powerful jet engines were tested on the Lancaster’s outer engine pylons, supplemented by the operation of the original Rolls-Royce Merlin engines at their original inboard mountings working the aircraft’s basic monitoring systems. Avro Canada CF-100 Mk 5 Canuck CF-100 Mk 5 serial 100760 engine test bed. (Bill Upton Collection) United Aircraft of Canada Limited had arranged for the long-term loan of a surplus RCAF Avro Canada CF-100 Mk 5 interceptor in 1967 towards use as a flying test bed for the JT15D turbofan engine, to be used principally on the Cessna Citation business jet.