The Decorators Team Fliers

Felix Mottram

Revolution JMH 1991 1.5 Sail

Re-making Bristol raffle sail.

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The kite that Rich Comrass had won in the Bristol benefit raffle was sent back to us by Alden Miller. It was flown at Blackheath 7th November 2021 and I noted that the sail appeared to be very tight laterally.
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On measuring against the Rev 1.5 profile drawing that I had used for the 2007 JMH Vented design sails it was found to be about 3.5cm narrower across the leading edge.
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A tracing is prepared for the template drawing. 10cm dacron has been laid out to compare with the original Rev 1 design from 1991. The black band width may be reduced to 9cm.
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The initial drawing has been prepared on 28th December 2023 and the options for reducing the band width are under consideration. As always with Jørgen's designs there is very little leeway in the overall configuration. Everything should just fit!
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At this point it seemed sensible to check the original drawings for comparison before proceeding further.

The idea had been to initially approach the scaling down from the original sail from 1991 with a view to establishing the design adjustments that might be needed.

Slight changes in the basic profile can have a considerable impact on Jørgen's design elements. The switch from a straight to a curved profile occurred at some point and Jørgen's early drawings assumed a straight leading edge!
The original faxed drawing from 7th December 1990 has recently been located. It would have been on 3 pages but the design chosen, page 2, had been removed.
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The drawings that Martin Lester used when making the sails originally are here and I have started to check against the actual sails.

The blue sail from the Bristol Raffle in 2009 has now been compared to the original drawing.
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An original sail from the 1997 set was also on hand for comparison. There are two drawings for this set, one from 1997 and the other, presumably from 2015, when a second set were made.

There are some slight differences in the basic profiles which will have to be assessed.
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The 2009 sail is laid over the 1997 sail showing the overall reduction but also the consistency of the profile given some indication of sail stretching.
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The 2009 sail is laid over the 1991 sail showing the crucial design decisions that could be made.

My inclination would be to maintain the angles between the black elements and maybe keep the width close, if not the same.
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The drawing was adjusted accordingly and then it became apparent that if rotated around the one end point the pattern would sit at the same points at each end and give the correct seperation at the central area.
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The weight was used as the centre of rotation while maintaining the angular relationship.
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A clean tracing was made for pattern making.
Site Updated June 2025 Felix Mottram