FEATURE MACHINERY
ADDITIVE MANUFACTURING revives Hawker Typhoon aircraft
A project to restore a heritage aircraft has become reality with the help of Renishaw which produced brackets from drawings using the latest metal additive manufacturing techniques
F
or almost two decades the Jet Age Museum in Gloucester, UK has been
working on bringing a Hawker Typhoon aircraft back to the city that originally manufactured it. Struggling to find engineering companies capable of recreating the complete brackets from the original 1938 drawings which lacked manufacturing details, the museum contacted Renishaw. Eager to help, the global engineering
company produced the unconventional brackets for the cockpit using the latest metal additive manufacturing (3D printing) technology, allowing the restoration project to continue. Only 3,317 Typhoons were made and there are only a few around today, none in flying condition. In 1998 when an almost complete but exceedingly corroded cockpit section was found at a scrapyard in Wiltshire volunteers vowed to restore an aircraft with a rich national and regional importance. Located just down the road from the birthplace of the Typhoon in Gloucester, the Jet Age Museum is pushing forward with the project today.
CHALLENGES The museum was unable to locate replacements for the original brackets and had trouble finding a manufacturer who could accurately reproduce the parts. "The Hawker Typhoon is an incredibly
important part of Gloucester's heritage," explains Typhoon sponsor coordinator Trevor Davies. “Our workshop containing the Typhoon cockpit is less than a mile away from where they manufactured the original aircraft in the 1930s. “To bring an original Typhoon back to the city would not only be an incredible engineering achievement but would be like recreating history. The unique shape of the brackets meant that although we had the original drawings CNC machining companies weren't confident they could produce an accurate finished part. When we heard about Renishaw's additive manufacturing capabilities and the design flexibility the technology offers we got in touch hoping the company could help us." "The original drawings the Jet Age
Museum had for the Typhoon date back to 1938 and all the measurements are in
14 DECEMBER/JANUARY 2017 | FACTORY EQUIPMENT
manufacture the final builds in metal. The Gloucester Aircraft Company originally made Typhoon cockpit brackets in aluminium because of the metal's physical properties: low density and therefore low weight, high strength and malleability. Renishaw occasionally uses plastic to additively manufacture prototype parts before producing the final build in a specified metal with the desired properties for the application. Renishaw produced the metal brackets
from aluminium powder in four separate builds using one of its AM250 additive manufacturing machines; the parts were then surface finished using a mix of bead blasting and hand finishing techniques.
imperial units," describes Joshua Whitmore, a development technician at Renishaw. "Furthermore, they didn't have the drawing for one of the brackets used in the cockpit which meant additional measurements were required for this part. “Because the brackets were on loan from another Hawker Typhoon, Renishaw only had them for a limited time. This imposed additional constraints on the project. “We had to estimate the dimensions
from the incomplete set of original drawings; using conventional measurement tools and equipment such as a digital vernier and shadowgraph we were able to obtain most of the missing critical dimensions while estimating non- critical ones and convert them from metric to imperial. The process was more time consuming but we managed to produce prototypes after about two weeks."
SOLUTION Renishaw used the original drawings and additional measurements to create a 3D digital model of the Typhoon bracket using Siemens NX 7.5 CAD software. This allowed the company to conduct parametric and direct surface modelling to produce digital replicas of the parts. Once completed the engineers
3D printed prototype parts in plastic polycarbonate. Renishaw then delivered these to the museum's workshop and fitted them to the cockpit to make sure they were the right specification. When engineers confirmed the parts were accurate Renishaw proceeded to additively
Recreating the aircraft brackets has been possible using the latest 3D printing technology
RESULTS Renishaw hand delivered the finished brackets in May 2016 just in time for the Cool Aeronautics show during which the engineering company collaborated with the Jet Age Museum to show off the parts and highlight the benefits of additive manufacturing to the public. "We can't put a price on what Renishaw has done for the Typhoon, the museum and the local community," says Davies. "We would not have been able to reproduce these brackets without additive manufacturing technology; the parts are too unconventional, a little bit like the Typhoon itself. By combining the old and new Renishaw has helped keep a project started in 1998 alive and well and brought one of Britain’s iconic fighter aircraft back home. We regularly hold school talks at the museum to encourage future generations to take an interest in engineering and aeronautics. Additive manufacturing is now a very real part of the Typhoon's illustrious history." By taking an additive manufacturing approach to the cockpit brackets Renishaw succeeded in producing the part to the 1938 engineering drawings in the original material. Since the successful completion Renishaw has been talking with the Jet Age Museum about returning another major piece of the Typhoon to Gloucester, the Napier Sabre piston engine.
Renishaw
www.renishaw.com/additive
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