MIAMI – Today in Aviation, the Comet 1 prototype took to the skies for the first time from Hatfield Aerodrome in Hertfordshire, UK, in 1949. The de Havilland DH.106 Comet was to be the world’s first commercial jet airliner.

The aircraft featured an aerodynamically clean design with four de Havilland Ghost turbojet engines buried in the wing roots, a pressurized cabin, and large square windows. For the era, it offered a relatively quiet, comfortable passenger cabin and was commercially promising at its debut in 1952.

Within a year of entering airline service, complications began to appear, with three Comets being lost due to catastrophic in-flight break-ups. Two of these were discovered to be the consequence of structural collapse caused by metal fatigue in the aircraft, a phenomenon that was not well understood at the time; the other was due to over-stressing of the airframe during flight through severe weather. The Comet was taken out of service and thoroughly tested.

Design and construction issues, such as faulty riveting and unsafe stress concentrations around some of the square windows, were eventually uncovered. As a result, the Comet was completely redesigned, with oval windows, structural reinforcements, and other modifications.

Other manufacturers took notice of the lessons learned from the Comet while constructing their own aircraft.

A Comet 1’s fuselage and de Havilland Ghost engine intakes. Photo: Tony Hisgett from Birmingham, UK – Comet front. Uploaded by oxyman, CC BY 2.0, https://commons.wikimedia.org/w/index.php?curid=10539191

Development


On March 11, 1943, the United Kingdom’s Cabinet established the Brabazon Committee, which was responsible for determining the United Kingdom’s airliner requirements following the end of World War II. One of its recommendations was to develop and manufacture a pressurized transatlantic Mailplane capable of carrying 1 long ton (2,200 lb; 1,000 kg) of freight at a nonstop cruising speed of 400 mph (640 km/h).

De Havilland was interested in this demand but chose to question the widely accepted belief at the time that jet engines were too fuel-hungry and unstable for such a function.

As a result, committee member and de Havilland business chief Sir Geoffrey de Havilland used his personal influence and his firm’s experience to support the creation of a jet-propelled aircraft, submitting a specification for a pure turbojet-powered design. The committee approved the concept, naming it the “Type IV” (of five designs), and gave de Havilland a research and production contract in 1945 under the designation Type 106.

The type and design were to be so advanced that de Havilland had to design and develop both the airframe and the engines.

The flight deck of a Comet 4. Photo: By Geni – Photo: geni, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=19810682

Design


The Comet was an all-metal low-wing cantilever monoplane powered by four jet engines, with two pilots, a flight engineer, and a navigator sharing a four-person cockpit. The aircraft’s sleek low-drag design had numerous design aspects that were unusual at the time, such as a swept-wing leading-edge, integral wing fuel tanks, and four-wheel bogie main undercarriage components created by de Havilland.

Two sets of turbojet engines (on the Comet 1s, Halford H.2 Ghosts, later renamed de Havilland Ghost 50 Mk1) were hidden in the wings.

The quiet, “vibration-free flying” advertised by BOAC was one of the most noticeable elements of Comet travel. Smooth and quiet jet flying was a fresh experience for passengers accustomed to propeller-driven airliners. De Havilland planned the Comet’s flight deck layout to be comparable to the Lockheed Constellation, an aircraft popular at the time with significant customers such as BOAC, for ease of training and fleet conversion.

The captain and first officer had full dual controls in the cockpit, while a flight engineer was in charge of numerous vital systems like fuel, air conditioning, and electrical systems. The navigator had his or her own station, with a table across from the flight engineer.

Several of the Comet’s avionics technologies were novel in the civil aviation world. One such feature was irreversible, powered flight controls, which improved pilot control and aircraft safety by preventing aerodynamic forces from changing the directed positions and placement of the aircraft’s control surfaces.

BOAC Comet 1 at Entebbe Airport, Uganda in 1952. Photo: By BOAC_Comet_1952.jpg: Ministry of Information official photographer derivative work: Altair78 – This file was derived from BOAC Comet 1952.jpg: Public Domain, https://commons.wikimedia.org/w/index.php?curid=19710659

Maiden Flight


On July 27, 1949, it was a pleasant and tranquil day in Hatfield, United Kingdom. The doors to a massive hangar opened, revealing a sleek, metallic tail through the gap. It glistened in the sunlight, generating awe and pride among the British journalists who had gathered to witness the unveiling at de Havilland’s private airstrip.

That moment, probably more than any other, marked the beginning of commercial aviation’s jet age. It was, however, more momentous and far more remarkable than the jet’s inaugural flight.

The flight had not been scheduled for that day. The prototype had been completing ground tests for some time and, after a lengthy photo shoot, was on its way to the runway for a few high-speed passes. The Comet was then positioned at the end of the runway and its engines were revved to take-off power while the brakes were engaged.

The four Ghost turbojets’ high-pitched roar filled the air. They were the most powerful engines on any civilian aircraft at the time. Jet engines were virtually unknown to the general public a few years ago, a technology that was thought to be too expensive, too experimental, and too secret to ever achieve mass manufacture.

And so, the demonstration of the sleek, bare-metal fuselage of the Comet 1 and the power of its four wonder-engines housed therein heralded the arrival of the jet age.


Featured image: Comet 1 prototype (with square windows) at Hatfield Aerodrome in October 1949. Photo: British official photographer – This is photograph ATP 18376C from the collections of the Imperial War Museums., Public Domain, https://commons.wikimedia.org/w/index.php?curid=18083161. Article sources: de Havilland, aerotime.aero.