QMT Features: November 2011
Spitfire enters digital age
Mobile 3D digital scanning has captured the very essence of the last airworthy Spitfire.


Creating a model of one of the most iconic pieces of aviation history is no small task. That’s why Amalgam Fine Model Cars asked Surrey-based Physical Digital, who specialise in optical scanning and design solutions, to spend three days at RAF Coningsby scanning the last airworthy Spitfire MkIIa that flew sorties in the Battle of Britain during World War II. The resulting model is destined for the collection of renowned architect Lord Foster, who commissioned the project, based on a long-term partnership between Foster & Partners and Amalgam.

A project like this is complex for a variety of reasons. Most importantly, the integrity of the aircraft has to be maintained, so moving it for scanning purposes isn’t an option.  Mobile 3D scanning instruments are the best option for large machines that need to be kept in controlled environments.  In addition, as part of the Battle of Britain Memorial Flight (BBMF), the Spitfire is at an operational RAF base, and scanning procedures can not interfere with the day-to-day operation of the base. The topography of the Spitfire also requires different types of scanning systems in order to produce the information needed for an exact scale model. For all those reasons, the company producing the final model, Amalgam Fine Model Cars, needed mobile scanning expertise.

Scanning solution
Physical Digital has worked on a wide range of international projects in the past and offers design and scanning solution for clients. Projects include Formula 1 and automotive, heavy engineering, marine craft and aeronautical designs and recently working on digitising Ralph Lauren’s classic car collection. managing director, Tim Rapley, said: “We knew from experience that we would need several scanning options in order to collect every piece of relevant data from the Spitfire. Forward planning is essential on a project like this, as it helps us to achieve the right result and reduces the amount of time we spend on-site.” Data from the scanning will be used both for the creation of the model, and also archived with the BBMF for use in refurbishment or repair work on the aircraft.

For the Spitfire project, Physical Digital used GOM systems TRITOP, ATOS and Touch Probe to ensure that the data captured was as comprehensive as possible.

• TRITOP – Photogrammetry technology uses coded and un-coded markers to create a framework for the subject. For the Spitfire, 5mm diameter markers were used across the frame of the plane. Moveable parts like the cockpit, rudder, ailerons and elevators were captured in their extreme positions in order for the model to show the deflection angles of these control surfaces. TRITOP allows for high levels of accuracy, in this case <0.02mm/m3. The resulting file builds a framework, based on creating 3D coordinates from 2D images. This file is then imported into the ATOS software where it is used as a reference frame for the 3D scanning process.

• ATOS – For this project, Physical Digital used two scanning systems to significantly reduce the project timescale, an ATOS IIe and an ATOS III Triple Scan, which is the latest system available from GOM UK.  The combination of these two systems enables them to capture the components and positions and compile the data into a single project. 3D scanning produces a mesh file that in this case will be used both to create a physical model, and for digital archiving by the Battle of Britain Memorial Flight.

• Touch Probe – in a construction as complex as the Spitfire, there are areas where conventional TRITOP and ATOS scanning will not produce the best results. Here, the optically tracked Touch Probe is used, this interacts with the ATOS sensor so that difficult-to-scan areas such can be captured and recorded accurately.

• GEOMAGIC – this specialist software was used by Physical Digital to rapidly create CAD models from the scan data.  This allows new components and tools to be reverse engineered, re- designed, optimised and manufactured with precision.

Modelling an icon
Once the data has been captured and processed, the model makers begin work on a project which will take several thousand man-hours to complete. An entire master set of components needs to be modelled using a range of skills, including digital machining, traditional engineering and hand crafting skills. Once the components are complete, they are painted and finished in exactly the same way as the original aircraft would be, resulting in accurate colour, finish and polish detail. When the components are finished, it takes another 300 hours of modelling expertise to assemble the model.  Each finished model will come with a replica log book.

Sandy Copeman, managing director at Amalgam Fine Model Cars said, “Everyone involved with this project has been hugely excited by the potential and the challenges it presents. We knew that we needed accurate, mobile digital scanning to produce the most precise model, and the team at Physical Digital know exactly what they are doing as their experience in working on priceless and classic engineering pieces across the world is invaluable.”

www.physicaldigital.com
www.raf.mod.uk/bbmf
www.finemodelcars.com

  
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