The First SST: The First Airliner to Break the Sound Barrier

One would anticipate an airplane slated for a report flight try to be prepped and flawless right down to the final rivet, however earlier than it even left the Douglas Plane plant in California the DC-8 chosen for this explicit try was not factory-fresh. In an interview with aviation historian Invoice Was­serzieher for a Douglas worker oral historical past venture, flight take a look at engineer Richard H. Edwards recalled, “The evening earlier than, at Lengthy Seashore, someone had dinged the [wing leading-edge] slats they usually didn’t work.” And in the course of the preflight verify Edwards broken the trailing-edge flaps, banging one on a flight crew workstand inadvertently left beneath it.

With out slats and flaps, low-speed dealing with was going to be difficult. Fortunately, this crew wasn’t aiming for a low-speed report. Pilot William Magruder informed them, “Nicely, we will take off with no flaps and the airplane can be all proper…if we don’t lose an engine.”

From left: Magruder, Alvin M. “Tex” Johnston and Lt. Col. Man M. Townsend confer close to the YB-52, which made its first flight on April 15, 1952. (U.S. Air Pressure/Getty Photos)

Douglas had quite a bit driving on the flight. Over the earlier decade Boeing had nearly locked up the marketplace for army bombers with its B-47 and B-52. Now with Boeing’s new 707 jet airliner (first flown in December 1957), the corporate was in search of to do the identical to the industrial market. Douglas had gained an enormous head begin within the airliner enterprise with its legendary prewar DC-3, however its new four-jet DC-8 had not flown till six months after the 707 took off. 

Magruder had been copilot in 1958 on the DC-8’s maiden flight. As an Air Pressure take a look at pilot and engineer he had flown every part from the North American F-86 Sabre and Martin B-57 Canberra to the Douglas C-124 Globemaster II and B-52 Stratofortress. He had flown with Chuck Yeager, the primary man to exceed the velocity of sound in degree flight, and Alvin M. “Tex” Johnston, who had famously flown a Boeing 367-80 (707 prototype) by means of a double barrel roll, earlier than becoming a member of Douglas in 1956. “He was well-known within the trade and really articulate,” recalled Edwards, “effectively educated, with a number of new concepts.”

His latest thought was to seize headlines for the DC-8 by making it the primary industrial airliner to interrupt the sound barrier. “Very good,” agreed Edwards, “get it on the market, present the airplane can survive this and never collapse. Boeing won’t ever strive it [with the 707] as a result of they don’t wish to be second.”

The DC-8 was decidedly subsonic, designed to cruise at 542 mph at 35,000 ft (Mach .82). Douglas put an entire staff of engineers to work on the mathematics. Edwards recalled, “They needed to decide the pushover load issue, the dive angle, to make certain they acquired to Mach 1.01 at a fairly excessive altitude, so the airspeed wouldn’t be that prime up there.”

On the designated day, August 21, 1961, Magruder and Edwards had been joined on the Douglas plant in Lengthy Seashore by copilot Paul Patten and flight engineer Joseph Tomich. The plane chosen for the flight was a brand new DC-8-43, no. N9604Z, the a hundred and thirtieth constructed. The Sequence 40 was the primary airliner on this planet powered by turbofans, for improved effectivity and fewer noise and smoke.

Resplendent within the crimson and white colours of its new proprietor, Canadian Pacific Air Traces, and emblazoned with its new title, Empress of Montreal, the DC-8 regarded advantageous with its dinged slats and flaps closed—no person might inform the chicken was barely crippled. “We took off with flaps up,” admitted Edwards, “which is sort of a no-no as a result of at takeoff thrust, you’ll be able to’t management the airplane if it loses an engine with flaps up—there’s an interlock on the rudder.”

The DC-8 and F-104 fly at high altitude on August 21, 1961, before making the dive. (Courtesy of Mike Machat)
The DC-8 and F-104 fly at excessive altitude on August 21, 1961, earlier than making the dive. (Courtesy of Mike Machat)

The take a look at was to be performed about 80 miles to the north, over Askania Monitoring Vary at Edwards Air Pressure Base within the California desert. On the best way up the DC-8 rendezvoused with a two-seat North American F-100F Tremendous Sabre digicam ship and a Lock­heed F-104 Star­fighter chase airplane (flown by Magruder’s previous buddy Yeager) supplied by the USAF Flight Check Cen­ter, which additionally provided a climate bal­loon to confirm velocity and atmospheric knowledge. Over the southern tip of Rogers Dry Lake, Magruder leveled out at 50,090 ft, in itself a report for a civil airliner at the moment. “The factor that impressed me essentially the most was the darkish, black sky,” recalled Edwards. “I’d by no means seen something like that.”

From that altitude, the remainder of the flight could be downhill all the best way. It was Edwards’ job to know once they crossed the magic quantity. “The Mach quantity itself isn’t utilized in a dive as a goal as a result of it’s rather more correct to make use of airspeed,” he defined. “So each thousand ft I’d learn off to Invoice the airspeed on the subsequent altitude. As we had been coming down, I used to be speaking nearly on a regular basis as a result of at a descent price of 500 ft per second, each two seconds we had been 1,000 ft decrease. Looking the window—which I finished doing—it regarded prefer it was straight down.”

Because the airliner neared Mach 1 it compressed the air transferring over it into shock waves, able to tearing a poorly designed plane to items. “At .96 Mach it buffeted for some time,” remembered Edwards, “…and just a little above .96 it went away.”

However shock waves can even have an effect on management surfaces, to the purpose of decreasing and even reversing pilot enter. “I had mounted some cameras in the midst of the airplane, capturing out every window,” Edwards recalled. “I needed to catch the chase airplanes on the market, however I by no means noticed the chase airplanes within the photos. However it did present the ailerons flapping up because the shock wave left—I feel it was about .97 Mach. They went up about 5 levels, I feel—each side, fortuitously.” 

Magruder held the yoke regular as Empress made historical past. “Within the dive, at about 45,000 ft, it went to Mach 1.01 for perhaps 16 seconds,” mentioned Edwards. In truth, at 41,088 ft the DC-8 recorded Mach 1.012, 660.6 mph at that altitude. By then Magruder was already beginning to pull out, however as Edwards recalled, “The restoration was just a little scary.” 

When Magruder eased again on the yoke to drag out of the dive, the airplane barely responded. The elevators, not designed to function at such velocity, couldn’t overcome the supersonic airflow. The DC-8 was uncontrolled, hurtling earthward at simply over Mach 1, and in lower than a minute would impression the desert ground…except it tore aside in midair first.

“Nicely, I’ll use the stabilizer,” mentioned Magruder. Moreover the elevators on their trailing edges, the DC-8’s horizontal tailplanes (additionally referred to as stabilators) might rotate as one piece—not less than, at sub­sonic speeds. At 39,614 ft the DC-8 hit a most true airspeed of 662.5 mph.

The flight and ground crews for the DC-8 supersonic run included flight test engineer Richard Edwards (third from left). Magruder is standing behind the sign in a white shirt. (Courtesy of Richard H. Edwards via Caroline Sheen)
The flight and floor crews for the DC-8 supersonic run included flight take a look at engineer Richard Edwards (third from left). Magruder is standing behind the register a white shirt. (Courtesy of Richard H. Edwards through Caroline Sheen)

“The stabilizer wouldn’t run….due to the load,” recalled Edwards. Within the high-speed pullout, with the airliner ever so barely nose-up to the wind, the motor controlling the tailplane angle actually couldn’t overcome the air strain beneath the tail.

“What [Magruder] did, as a result of he was good, is one thing that no different pilot would do,” mentioned Edwards. “He pushed over into the dive extra, which relieved the load on the stabilizer.” 

It was unconventional pondering—improve the dive price to drag out of a dive? However as quickly as Magruder stopped attempting to drag out, the airliner “straightened out” into the wind, and the lowered air strain allowed the tailplane motor to operate and the stabilators to chew into the airflow. They “recovered at about 35,000 ft,” Edwards famous, little doubt with a way of reduction.

In the midst of the dive the DC-8 had lined nearly 15 miles, to the southern tip of Rosamond Dry Lake. “We had been all smiles,” mentioned Edwards. “We weren’t frightened, however we had been kind of completely satisfied that we had acquired there.”

In simply that one flight, Empress of Montreal had set altitude, payload and velocity information for industrial transport plane. The velocity report stood till damaged by a Soviet Tupolev Tu-144 SST in June 1969. Every crewman acquired a $1,000 bonus from Douglas, and the Society for Experimental Check Pilots awarded Magruder the Iven C. Kincheloe Trophy for excellent skilled accomplishment in flight testing. 

Canadian Pacific took supply of Empress of Montreal that November. With a small plaque on the ahead bulkhead testifying to its place in historical past, it served for nearly 20 years, logging 24,268 flights for a complete of 70,567 hours within the air. In Might 1981 it was bought, and at Opa Locka Municipal Airport north of Miami, Fla., scrapped. It by no means broke the sound barrier once more.  

The Fourth SST

DC-8 no. N9604Z was the primary airliner to exceed Mach 1, however not the final. The Concorde and Tu-144 made supersonic passenger flight appear routine (not less than, till a collection of crashes and financial concerns brought on their retirement). At this time most industrial airplanes just like the Boeing 787 and Airbus A350 cruise round Mach 0.85 to 0.89, whereas smaller company jets from Cessna, Gulfstream and Bombardier routinely cruise above Mach 0.90. It’s not extraordinary, nonetheless, for subsonic airliners to exceed Mach 1 (761 mph at sea degree), not less than by way of floor velocity.

In February 2018 a Norwegian Air 787-9 heading from New York to London caught a experience on the jet stream over the Atlantic. Dreamliners had beforehand reached 776 mph with a tailwind, however this one made the crossing in 5 hours and 9 minutes, topping out at 799 mph. And a 12 months later, a Virgin Atlantic 787-9 out of Los Angeles on its method to London additionally caught the jet stream 35,000 ft over Pennsylvania, attaining a floor velocity of 801 mph. As a result of the high-speed wind was carrying the jets like boats on a river, these airplanes didn’t exceed Mach 1 as measured by native airspeed. At the least one different non-SST airliner, nonetheless, did break the velocity of sound…although not deliberately.

In April 1979 a TWA 727 suffered a slat retraction failure and entered into an uncontrolled spiral dive during which it exceeded the speed of sound. (Courtesy of John Proctor via Emilio Corsetti)
In April 1979 a TWA 727 suffered a slat retraction failure and entered into an uncontrolled spiral dive throughout which it exceeded the velocity of sound. (Courtesy of John Proctor through Emilio Corsetti)

In April 1979 TWA Flight 841, a Boeing 727-31 en route from New York Metropolis to Minneapolis-Saint Paul, Minn., deployed the no. 7 modern slat on its starboard wing whereas cruising at Mach .816, 39,000 ft over Saginaw, Mich. Slats being low-speed, high-lift units, the ensuing asymmetrical carry and drag instantly threw the airliner right into a starboard roll. It entered into an uncontrolled spiral dive and plunged about 6 miles in 63 seconds, in response to the flight recorder doing two full 360-degree rolls and breaking the sound barrier within the course of. At that velocity the wind tore off the uncovered slat, the captain dropped the touchdown gear to place most drag on the airframe and the crew regained management with about 8,000 ft to spare. They made a profitable emergency touchdown in Detroit. 

Regardless of broken touchdown gear, components of flaps and wing spoilers lacking and a number of different injury together with a cracked cabin window, the passengers and crew suffered solely minor accidents. The plane was returned to service a month later. A Nationwide Transportation Security Board investigation attributed the incident to incorrect operation of the slats by the crew. (A rumor had circulated that barely deploying slats and flaps at cruising velocity elevated the 727’s carry with no improve in drag, yielding higher gasoline effectivity. In line with the NTSB, the crew had deployed all of the slats, however resulting from air loading no. 7 didn’t retract.) The crew strongly denied wrongdoing, declaring seven earlier incidents of single-slat extensions by 727s.

Frequent contributor Don Hollway final wrote for us about Normal Curtis LeMay within the November 2021 challenge. His most up-to-date e-book, The Final Viking, was launched in September 2021 to important acclaim. Additional studying: Douglas DC-8, by Terry Waddington.

This characteristic initially appeared within the March 2022 challenge of Aviation Historical past. Don’t miss a difficulty Subscribe!


Leave a Reply

GIPHY App Key not set. Please check settings