The square-ish cabin windows was only "part of" but not the primary cause the of accidents which afflicted COMET 1.
The microscopic fatigue fractures that were later proven to have been the cause of 1 of the 2 major BOAC disasters actually stemmed from manufacturing defects .... punched-in rivets near an upper fuselage ADF housing on BOAC's G-ALYP and which propagated further through the natural stresses of pressurization cycles and eventually grew to cause the fuselage to explode.
The precise failure of G-ALYY was never determined with the same precision, but, was proven to have been caused by the same phenomenon as had afflicted G-ALYP .... given evidence exhibited by those bodies that were recovered.
Investigative testing of COMET 1 aircraft following the G-ALYP and G-ALYY accidents determined that stress loadings around fuselage/cabin window cut-outs (due to there square-ish design) were 60% greater than DH had anticipated .... but .... it wasn't the PAX cabin windows which failed or propagated the cracking that caused the fuselage to eventually fail in the case of both BOAC accidents.
DH engineers had expressed concern during the construction of COMET 1 that the thin gauge of metal alloy used for the aircrafts skin was difficult to form and prone to cracking during manufacture .... requiring a stop-drilling practice being applied to arrest cracking when it did occur.
There were other design issues too which afflicted COMET1 .... particularly in regard to aircraft handling .... as BOAC and CPA both learned to their cost ....
The aircrafts rotation axis for T/O had to be set with "precision" .... exceeding a desirable rotation axis deprived the engines of air-flow and a stalled T/O would result.
The aircrafts wing leading edge and engine nacelle shape was also less than efficient and contributed to the stalled-T/O phenomenon .... and redesigned for COMET 1A.
As horrendous as this might all seem today .... this was a pioneering era in aviation technology in terms of both production and jetliner operation.
No one had ever built a jetliner before.
No one had ever flown a jetliner before.
And .... lessons were learned .... often the hard way .... and maybe we're still in the latter stage even today as the case of any number of accidents have proven during more recent times.
The COMET was a world leader .... for its time .... BUT .... whilst those whom trail-blaze are generally the very first to reap the benefits of their ingenuity they can also become the first to suffer the consequences of their pioneering efforts .... and from which ones competitors will inevitably learn and advance .... as the COMET clearly proved.
CPA became the first foreign order for COMET jetliners .... followed by AIR FRANCE and UAT AEROMRITIME). The airline ordered both COMET 1A and -2 versions intending to launch jet-services between Sydney and Vancouver (operated via Nandi, Canton Island, and Honolulu .... and also Auckland, Nandi, Canton Island, and Honolulu). Their first aircraft .... CF-CUN "Empress Of Hawaii" .... was W/O on its delivery flight to Australia during a failed T/O attempt (over-rotation and stall) from Karachi on March 3rd 1953 and with the loss of all POB.
CPA COMET CRASH (video)www.youtube.com/watch?v=qp2FMS05KI0Following this accident CPA refused to take delivery of its remaining COMET 1A (CF-CUM). It converted its order to COMET 2's instead .... but .... this order was cancelled entirely following the BOAC disasters of 1954.
The remaining originally CPA was delivered to the RCAF later during 1953 .... along with a 2nd aircraft too. Following the 2 BOAC COMET disasters of 1954 both RCAF aircraft were returned to DH during 1956, modified to COMET 1XB specification, and then redelivered to the RCAF during 1957 .... where they remained in service until 1965.
Mark C
AKL/NZ
