Sporting a conventional vertical and horizontal tail, the DH.106 rested on a tricycle undercarriage, whose main units initially retained the single wheels of the prototype. The Comet was, in every sense of the word, a piece of engineering art-especially for its time.

Its circular-section, ten-foot-wide fuselage, to which its air cleaving nose was attached, was of all-metal, semi-monocoque construction, employing 22-gauge alloy and Redux bonding to eliminate the  pre rolled cones   increased weight and leak propensity holes otherwise associated with riveting methods. Overall length was 93 feet.

The 20-degree swept wings, spanning 115 feet and encompassing a 2,027-square-foot area that gave it a 52.2-pound-per-square foot loading, were equally of all-metal, two-spar construction, and they consisted of a stub wing section, which housed the engines, a center section, and an extension section.

Its aerodynamic devices included hydraulically actuated air brakes, ailerons, and hinged, trailing edge flaps. Wing deicing was accomplished by thermal means and the internal, bag-type fuel tanks, pressure introduced at a 40,000-pound-per-thirty-minute rate, had a 6,000-Imperial gallon capacity.

The cantilever tailplane, consisting of a variable-incidence horizontal surface and a rudder-installed vertical one, gave the aircraft a 28.5-foot overall height.

The four 5,000 thrust-pound de Havilland centrifugal-compressor Ghost 50 engines, passing through both the forward and rear spars at their wing root installation points, contained none of the cylinders, cylinder heads, pistons, connecting rods, valves, valve springs, tappets, carburation units, electric ignition reduction gear, or propellers hitherto associated with piston powerplants. Their inherent weight reduction, increased simplicity, and minimal drag installation produced the optimum aerodynamic configuration.

The latter was both high enough to avoid foreign object ingestion and low enough to facilitate maintenance and inspection, enabling the aircraft to employ shorter undercarriage struts, which themselves reduced structural weight. The engines' own such reduction also enabled more fuel and/or payload to be carried, at the same time incorporating ideal anti-icing capability and fire prevention.

Because of the originally intended 40-degree wing sweepback, which would have required significantly greater rotation and airborne speeds and therefore longer runways, there was provision for a jet-assisted takeoff (JATO) hydrogen peroxide sprite rocket.