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I was contacted by Peter Ross
after I had posed the question of Lotus Seven Series Two frame
failures on several related email lists. He wrote:
I sent copies of the messages
about frame failures recently reported on the chapman-era list
to my friend Gilbert 'Mac' McIntosh, who designed the Series
1 frame with Colin Chapman one Sunday in Winter 1956/57. He has
indicated he is very interested and would like to know more.
Mac has also offered to write the
story of how they designed this car to avoid doing the washing
up after lunch at Gothic Cottage. He
may be prepared to suggest ways in which the S2 frame could be
strengthened for increased power/traction in a way that adds
the very minimum of weight. This is the sort of chap he is.
By way of background I should
explain that Mac was a respected designer in the de Havilland
drawing office at the time of the Comet, and was later responsible
for the mid-engine design for the Trident (which was the inspiration
for the Boeing 727). He got
involved with Lotus through me (I was an apprentice at de H at
the time) in 1952 whilst I was helping Adam Currie build and
develop his Lotus IIIb. Mac beat out the bulge which covered
the magneto (later changed to coil) and carburettor.
At the end of the 1953 racing
season Adam sold his car and was due to have the second Mk 8
to be fitted with a Coventry Climax engine. Mac was shown a drawing
of the Mk 8 frame, on which I did some stress analysis, and came
down to the Works at Hornsey to have a look. He was immediately
given the job of designing all the bracket for the frame to take
the suspension and engine mountings etc.
After that Mac became one of
the volunteer gang, with Adam and me and several others, that
worked long hours of spare time to build SAR5, and afterwards
he collaborated with Colin on Lotus chassis design, trying to
make it more "aircraft-like". The first effort was
the Mk 9 space frame for the works cars, which was similar to
the Eleven. He later did the Eleven S1, Twelve, Eleven S2, Seven
and stress analysis for the Elite.
In 1956 Colin let us both buy
an Eleven at cost. Mac made his into a hard top touring car with
Ford engine, and I decided to race mine, first with an 803cc
Austin A30 engine, and then, in 1957, with a Series 2 Climax
1100. Mac "committed
matrimony" in 1957, and gave up helping Colin, although
they remained friends. I went on helping Colin on the design
side until about 1959.
-summer, 2002
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