Comet Aircraft
Fatigue Failure
Group 6
Background….
• Designed by De Havilland
-the first turbojet powered airliner
-competition between USA (Boeing) and Britain to
produce the most successful commercial aircraft
• 27th July 1949 – flight of the first prototype
• The first passenger flights began in 1952
-From London to Johannesburg
-Flight time decreased from 40 to 23 hours
All seemed well!!......
•
•
•
•
•
Smooth engine
Fuel Efficient
Low Maintenance Costs
Little Vibration
Pressurised Cabin - Could fly
over storms when other aircraft
had to fly through them
Technical Description…
•
Length ~ 90 – 100 feet
-Very comfy with only 11 rows of seats!!
•
Thin metal skin (“Redux” panels) with low
wings
-Lightweight, low drag design
•
Pressurised Cabins
•
4 Ghost 50 turbofan engines in the wings
-more complicated wing structure
-again, less drag
Just when they thought
they had it… 
• 1952
Rome: failed to become airborne
Pakistan: ran into bridge, 11+ fatalities
-both blamed on pilot, later found to be aircraft
• 1953
Calcutta: disintegrated in thunderstorm
-design fault → wing design reprofiled
-43 fatalities
• 1954
Italy: exploded and fell into sea
-initially believed fire was the cause, next accident proved otherwise
-35 fatalities
More accidents…
• 1954
Naples: disappeared, remains found in sea..
-after expensive testing the cause of both these 1954 accidents was
found to be…
FATIGUE
Testing…..
• Full-scale flight simulation testing began
• Large tank was built to hold an aircraft, water was used
to imitate cabin pressurisation cycles and wings were
jacked to simulate typical flexing
Test Results……
• Stress around windows was higher than expected,
due to stress concentration caused by square shape
• Poor placement of engines in wing design, had
negative effect on lift-off potential and was a fire
hazard
• Many modifications were made.. windows were
redesigned to an oval shape and the skin sheeting
was thickened, flights started again…..
4 years later!
Oh Well…!
• The damage done to the Comet Aircraft’s reputation was beyond
repair
• Boeing had taken the lead with commercial jet manufacturing
• Production of the Comet Aircrafts ceased after just another 10
years…..
Into the Future…and
Beyond!!
•Full-scale testing of aircrafts
used in future
•Much better understanding of
fatigue and fatigue testing
achieved
•Learned the importance of
minimizing stress
concentrations
•New knowledge of materials
Thanking You!!!