Chelsea Flower Show – Swallowtail Pavilion

The Swallowtail Pavilion is named after the shapes that lie at its centre. The pair of swallowtails are not a physical form, but the overlay of the translucent surface with itself. The outline of overlapping portions of the surface form unexpected, complex and beautiful forms that shift and change as you move around the pavilion. These shapes were termed ‘catastrophes’ by the iconoclastic mathematician Rene Thom and the relationship between Thom’s theorems of structural stability and its impact on the art of Salvador Dali, Naum Gabo and others are the subject of Allan McRobie’s book ‘The Seduction of Curves’.

Following the release of the book, Allan was asked by the award-winning garden designer Jo Thompson to create a sculpture for the 2018 Chelsea Flower Show, and Expedition were brought on board soon after.

The very complex form of the pavilion and its twisting lines and surface defy drawing, and even photographs do not fully capture its richness. It was appropriate, then, that the first communication of Allan’s concept was a physical model, made from copper pipe and thread. The design team could walk around the model, change its angle and position on the table, and suggest how it might be supported, with well informed decisions being made immediately.

This early ‘model led session’ inspired us to replicate the proposal’s best features digitally, whilst expanding the variety of things that could be manipulated. A parametric model, where the key aspects of the design can be changed interactively whilst maintaining structural integrity, was the right tool. The idea being that crucial design decisions could happen in a single meeting, rather than extended iterations, with the design team generating, testing and improving ideas together.

The initial investment in producing the model paid off – the team reduced long periods of feedback and refinement with ‘live’ experimentation. Loading the most promising 3D models into a virtual reality headset allowed many of the features of the physical model to be preserved and even enhanced, with a better sense of scale and immersion. The increase in speed, as well as the enhanced visualisation this created, was vital for the project to be delivered on time and ensure all members of the design team were happy with the form.

Aside from the design process, the closeness of the design model, the structural model, and the fabrication model increased efficiency and speed when working with our fabricator Pemat AG. Geometry was taken from the design model and fed almost directly into the fabricating machine. This hard work in the virtual sphere saved time on the fabrication programme, allowing time to create a test version of the structure at Pemat’s Switzerland base.

In essence, our use of parametric modelling allowed an ‘intensely 3D’ form, to be created collectively and rapidly within a dynamic design team. We have helped turn a catastrophe into a beautiful garden of complex curves for Wedgwood’s Gold Medal award winning competition entry and we are enjoying exploring it.

Visit our project page to see more photographs of the design process and finished pavilion.

And jump to 10:25 in this clip from the BBC to see Jo discussing various stages of the construction as well as the finished garden!