COMET Chapter Seven - Old Accidents

I invite you to watch as the brazen brown and yellow aircraft designated “dash 80” slowly begins it's takeoff roll down runway 15/33. The four Pratt and Whitney turbojet engines, individually suspended below the 35 degree sweptback wings, roar as they produce 44,000 pounds of thrust. At 120 miles per hour pilot Alvin “Tex” Johnson firmly pulls back on the control column, and 200,000 pounds of aluminum alloy, wires, rubber tubing and ambitions float off the asphalt. It is 2:14 on Thursday afternoon of 15 July, 1954. The air above Lake Seattle is populated with puffy white clouds. And as the twin four-wheeled bogie tricycle gear of Dash 80 fold neatly into the underbelly, the grounded Comet jet transport is about to become obsolete. When he landed, 2 ½ hours later, “Tex” said, “She flew like a bird. Only faster.”

Douglas had dominated commercial aviation market since 1933, with their DC 3 (above) family of piston engine passenger planes. 

 Boeing survived thanks to their military contracts -  beginning with 17,000 B-17's built between 1935 and 1945. 

This was followed by almost 4,000 B-29 SuperFortereses built between 1942 and 1945.

Then Boeing built 2,000 swept wing B-47 Strato-jets between 1948 and 1963.

 Finally, beginning in 1951, Boeing supplied the U.S.A.F with 744 swept wing B-52 StratoFortress, still flying more than 60 years later.

So, when Bill Allen, president of Boeing Aircraft Company, saw the de Havilland Comet at the 1949 Farnborough Air Show (above), he was not impressed. But what the Comet high lighted to the Boeing engineers was that jet transports promised speed and reliability for anything you could fit in the pressure hull.

The United States Army Air Corps had been experimenting with mid-air refueling since 1927. Developments were slow, but by 1948 the USAF had two squadrons of beefed up double body B-29's Tankers, which Boeing initially called the 367s and which the U.S. Army relabeled the B-50 (above)

The problem was the jet bombers could not comfortably fly slow enough without stalling to be serviced by these piston driven gas tanks.  Also, at higher altitudes where the B-50's labored, the air was “smoother”, making refueling easier. Obviously the Air Force was going to need a jet powered tanker. And that was Boeing's initial justification to nervous investors when, in 1952 Allen asked them to risk 25% of Boeing's capital, some $16 million, to developing a jet tanker. But carrying fuel was only part of Boeing's idea.

Boeing labeled their new aircraft Project 367-80. Eventually it became known simply as the Dash 80. It was big - 128 feet long as opposed to the 93 foot long Comet – 130 foot wingspan to 115 feet for the Comet, and a wing area of 2,400 square feet to 2,015 square feet for the Comet. All that extra wing space, devoted entirely to fuel, gave the Dash 80 a range of 3,530 miles to the Comet's 1,500. 

The plane was so big a passenger version was projected to carry at least 140 seats, five abreast, compared to the Comet's 43 seats at two abreast, thus reducing the operating cost to 25 cents per seat-mile for every gallon of kerosene the four engines burned. Not to mention, the Dash 80 could cruise 100 mile per hour faster than the Comet. It looked like democracy with wings.

Boeing swept the wings of the Dash 80 back to 35 degrees, which they knew would be stable because that was the same angle as the wings on their bombers. And they avoided new engine development by using the same engines used in the bombers, and slung them beneath the wings for easy maintenance, and to free up wing space for fuel, just like the bombers. All of this would reduce the need to retool when and if the various versions of the plane went into production.

Boeing also learned from the well publicized crashes on Comet take offs by designing forward and rear facing extensions (flaps, tabs, ailerons and spoilers) on the swept wings of the Dash 80 (above). These allowed the big bird to stay in the air at speeds as low as 80 miles per hour. To allow passenger jet to use existing airfields of 7,000 feet, clam shell thrust reversers were included, to slow the jet from the landing speed of 150 miles per hour to dead stop within 6,000 feet.

However, the Dash 80 was neither a tanker nor a passenger plane. It was a test bed for both. That did not matter, it seemed, because almost before the 2 ½ hour maiden flight had landed, the Army ordered 29 of the new, yet as un-built planes to be labeled the “K” (meaning tanker) and “C” (meaning transport) -135 (above).  Another 250 KC-135's were quickly added to the order, the planes first reaching service in August of 1955.

The airlines, however, showed little interest, in part because 1954 was a recession year, but also because the disasters of the Comet were still fresh in the public mind. Few seemed eager to risk their lives on a passenger jet. So the Dash 80 flew on, amassing data to improve the design.

Meanwhile, on Tuesday, 1 February, 1955, the the British Civil Aircraft Court of Inquiry into the crashes of Comet Yoke Peter and Yoke Yoke was issued by the Royal Aircraft Establishment. The fault, they had determined, was “...metal fatigue, caused by the repeated pressurization and de-pressurization exacerbated by the thin aluminum alloy skin...” and the squared off windows which intensified pressures at the corners.

De Havilland responded with a public statement. "Now that the danger of high level fatigue in pressure cabins has been generally appreciated, de Havillands will take adequate measures...we propose to use thicker gauge materials...and to strengthen and redesign windows and cut outs and so lower the general stress to a level...(which) will not constitute a danger.” The company immediately began the work, but it would be 3 years before the redesigned Comet 4 could re-enter commercial service.

It was not until 2015, when the 50 years of silence required by the British government Secrets Act had expired that the full truth of the Comet hull failures was revelled. Said the originally redacted report, “...metal fatigue, attributed to raised stress at the squared-off window corners, actually had another cause....the structure had been designed to be bonded – glued, in fact – by...the Redux process...” 

However, “...During production...de Havilland chief designer, R.E. Bishop (above)... decided that these areas should...be reinforced...by normal aircraft riveting...It was this 'belt and braces' riveting...that caused the failures. The cracks emanated from the rivet holes in the corner area – not from the material in the corner structure itself.”

But it was Tex Johnson (above), the Boeing test pilot,  who drove the final nail in the Comet coffin. 

The stage was the annual Gold Cup hydroplane races to be held on Saturday 6 August, 1955 - light high speed boats powered by air craft engines, racing at 80 to 90 miles an hour across the surface of the water and throwing 30 foot high rooster tails behind them. Viewed by perhaps 200,000 spectators from the bluffs above Lake Washington, in 1955 for the first time the event was even broadcast on live television.

That same week, The International Air Transport Association and the Society of Aeronautical Engineers were both holding their conventions in Seattle. So Bill Allen invited a large number of aviation industry folks to attend the races, and had coordinated with the Dash – 80 team to do a fly by.  That was all Tex Johnson was supposed to do - fly by.

But Tex had heard that Douglas aircraft, which had started a crash program to build their own slighter smaller and slightly slower jet passenger plane, the DC 8 (above), was telling potential customers that the Boeing jet was unstable. 

Tex (above left) felt obliged to prove the critics wrong.  As the Dash 80 was in route to Lake Washington, he told his co—pilot Jim Gannet (above, right) , “Hey Jim, I'm going to roll this airplane over the Gold Cup." Gannet suggested if he did, Jim Allen would fire him.

Johnson then steered the big jet down to 500 feet for the fly-by east bound. And as he passed the spectators, Tex pulled up slightly and slipped the aircraft into a gentle roll to the right, 360 degrees - a perfect barrel roll. (Barrel Roll).  It was perfectly safe, according to “Tex”. “The airplane does not recognize attitude,” he later explained, “providing a maneuver is conducted at one G...The barrel roll is a one G maneuver and quite impressive, but the airplane never knows it’s inverted.” 

Then, on the west bound pass, he did it again.  During the second roll the flight engineer, the only other person on board, snapped a photo of the Bill Allen's $16 million gamble upside down less than a thousand feet above Seattle.

The gamble worked. Less than 2 months later, on 13 October, 1955, Pan American World Airlines ordered 20 of the newly designated Boeing 707 jets, to replace their cancelled Comet orders. 

The only fly in the ointment landed when Douglas upgraded the engines on their DC-8's, forcing Boeing to follow suit. That delay prevented the first 707 commercial flight until October of 1958. But by 1956 even British Overseas Airway Corporation had ordered Boeing's big jet. Until the production lines shut down in 1978, Boeing built 865 of the big 707 airplanes.

The British government remained loyal to the de Havilland Comet, and in March of 1955 British Overseas Aviation Corporation ordered 19 of the new Comet 4's (above). To extend its range, the Comet 4  had a fuel tank pod perched in each wing, and the wings themselves were bigger, as were the engines. 

On 4 October, 1958 it was a Comet 4 that flew the first jet London to New York flight, with a westbound refueling stop at Gander, Newfoundland. But the new Comets could only squeeze 99 passengers into the larger pressure cabin, and de Havilland's plane was still 50 miles per hour slower than either the Boeing 707 or the DC-8.  De Havilland sold only some 76 Comets, before production was stopped in 1964.

In 1960 de Havilland was acquired by Hawker Siddeley in a government brokered sale and the name de Havilland faded from British aviation. 

The Canadian government bought the subsidiary de Havilland Canada, and for the next 20 years produced a successful line of short take off and landing civilian aircraft. But in 1984 the conservative government of Brian Mulroney privatized the company, and in 1986 de Havilland Canada was bought by Boeing. Despite promises to Canada, Boeing closed the plant and broke up the jigs and all production equipment, and that really was the end of de Havilland.

Today, (2020) Boeing itself is reeling from their own self-engineered 737 Super Max debacle - 2 crashes and 346 dead, caused by a preventable failure  - followed by the COVID 19 pandemic which gutted air travel for an entire year.  

Boeing in 2020 seems to be facing a similar fate to the one de Havilland faced in 1954, building airplanes nobody wants to fly aboard. 

As one of the Farnborough engineers pointed out back in 1954, ‘There are rarely new accidents, just old accidents waiting for new people to have them.”

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