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Milestones: The First Airliner to Go Supersonic

By Stephan Wilkinson
10/23/2017 • Aviation History Magazine

No, it wasn’t the Concorde, nor was it the Tupolev Tu-144 “Koncordski.” The first airliner to exceed Mach 1 was a near-stock Douglas DC-8. And just to rub it in, the Diesel Eight carried the livery of a Canadian airline: Canadian Pacific.

It happened five decades ago, 15 years before the Concorde would carry its first paying passengers. The only change to the faster-than-sound DC-8’s airframe or engines was an experimental, spanwide, 4- percent extension of the wing leading edge, which was being tried not to make the airplane faster but to extend its range. The test plane took off from the Douglas factory at Long Beach, Calif., on August 21, 1961, loaded with enough ballast and fuel that it weighed 170,600 pounds when it reached top-of-climb at 50,000 feet—heavy enough that the airplane broke the existing altitude record for loaded jet transports on the same flight during which it went supersonic.

As revealed by a Douglas document published on the website of DC-8 enthusiast Fred Cox (dc-8jet.com), the test program was to gently push over into descents of 15, 20 and 25 degrees of dive angle. Douglas knew that pullout from the dives with shock-waved elevators at the potential Mach 1.03 speed were in let’s-give-it-a-shot territory, since the DC-8 had only been flighttested to Mach 0.95, its neverexceed speed. So each dive began with the DC-8’s stabilizer already trimmed up. This meant that it took a substantial 50 foot-pounds of force on the yoke to maintain the dive.

Accompanied by a Lockheed F-104 Starfighter paceplane as well as a North American F-100 Super Sabre photoplane, the Douglas DC-8 thundered through Mach 1.012, for a true airspeed of 662.5 mph, at 39,614 feet. The pilot maintained takeoff thrust throughout the dive, a good indication of how much power and momentum it takes to bull an airliner through the sound barrier.

 

Originally published in the September 2011 issue of Aviation History. To subscribe, click here

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