h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

I was struck by an unexplained anomlay in the research on the DH 106 Comet 1. You correctly give a table of operational ceilings for the Comet, Stratocruiser, DC-6 and Constellation, assuming early variant Constellation and go on to suggest that Sir Geoffrey de Havilland insisted on 'square' windows (strictly, rectangular with rounded edges) to differentiate the Comet from the US opposition.

However, the DC-6, which first flew before the Comet 1, on 15th February 1949 (as the XC-112A) had SQUARE windows, and moreover was pressurised, 'square' windows going on to become an industry standard for pressurised airliners (eg Boeing 707, 737 and 747).

The explanantion you give cannot be correct.

The ceiling tables, which are correct, illustrate another weakness with the Farnborough-generated accident theory for the destruction of Yoke Peter and Yoke Yoke. It is widely assumed that the Comets doubled the ceiling and cruising speed of existing airliners - as you rightly point out, the performance advantage was of the order of 50%, ie about half of that generally assumed.

The pressure differentials between the Comet 1 and Douglas DC-6 were not nearly as great as many assume.

Furthermore De Havillands extensively pressure tested the Comet fuselage, including water tank testing, well beyond pressure levels expected in service - the windows were tested at up to 100 lb per sq inch. The Comet 1 was subjected to the most sustained testing and development of any airliner then in service - nearly 3 years, compared with just over 4 months for the pressurised DC-6, which as you rightly say was intended for poerations above 20,000 ft.

There are other major, unexplained anomlaies in the accident theory.

The Farnborough test fuselage failed at well over the airframe life of both Yoke Yoke and Yoke Peter, more than 100% over in fact. Each was a nearly new airframe when it supposedly failed.

Extensive investigation of the Comet 1 feet did not show up major problems with fatigure cracks - hence the tank test, which would have been superfluous had cracks been found.

There have been numerous 'blow-out'incidents involving windows - even a cockpit window, on a BAC-111, which did not lead to the catastrophic break-up of the hull without time for a warning message. Other in-flight failures without warning (eg the BOAC 707 over Mount Fuji) have all involved severe turbulence or extreme weather conditions.

Air France and UAT also operated Comet 1s with similar utilisation - why did no French Comets crash?

Why did the failures occur at only FL260 approx, 16,000 feet below the service ceiling?

The answer is obvious, but I would welcome responses.