Aircraft Part 3D Scanning

Background

The Arctic Tern was an Alaskan bush plane produced in small numbers in the 1970s, designed for reliable use, durability and ease of maintenance in remote areas.  The rights to the airplane were eventually purchased by Thayer graduate Bart Miller, who sought to modernize the aircraft and improve its speed and service life.  Unfortunately, Bart Miller passed away in 2006, and his company, STOL Aviation, was later acquired by Charles Nearburg D’72 Th’74.  STOL Aviation is based out of the Lebanon, NH Municipal Airport.  The Thayer School Machine Shop is proud to support a local business, offer our services to alumni and play a part in the Arctic Tern’s continuing development, so that Bart Miller’s vision may one day be realized.

Arctic Tern

Arctic Tern

Engineering Problem

The update to the Arctic Tern includes a redesign to the cowling, which covers the engine at the front of the aircraft and must be designed to reduce drag and facilitate engine cooling.  In this stage of development, the general form of the cowling has been mocked-up to scale with thin aluminium strips, welding wire and masking tape by John Barker and Chuck Horrell D’00 Th’01 of STOL Aviation.  Machine shop researcher Max Fagin Th’11 seeks to use our handheld EXAscan 3D scanner to scan this mock-up into a digital form, where it will be further optimized by software and fabricated into a fiberglass mold for production.

Cowling Mock-Up: Masking Tape and Chicken Wire

Cowling Mock-Up: Masking Tape and Chicken Wire

Process

In order for our 3D scanner to determine the form of the cowling, retroreflectors must be applied to the surface to act as a spatial guide.  These are small stickers with black and white concentric circles that must be applied with adhesive to the scanning surface about an inch apart.  We applied these retroreflectors to the left side of the cowling mock-up.

John and Max Applying Retroreflectors to the Cowling

John and Max Applying Retroreflectors to the Cowling

Then, Max used our handheld EXAscan 3D scanner to read the cowling surface.  The scanner employs a laser rangefinder and uses the retroreflectors as a guide to create a digital rendering of the surface.  Max also selected three known points as anchor points to determine the surface’s orientation and size.  The scanner was connected to a laptop which displayed a real-time rendering of the scanned surface.

Max Scanning the Top of the Cowling

Max Scanning the Top of the Cowling

Max Scanning the Side of the Cowling

Max Scanning the Side of the Cowling

The final rendering contained 75,000 faces at a 2mm resolution.  Later, this scanned form will be further optimized by software and fabricated into a mold.  The imperfections and holes in the rendering will be interpolated and filled in automatically.  We’ll keep you updated with our progress in the future.

Max Scanning the Side of the Cowling with Real-Time Rendering

Max Scanning the Side of the Cowling with Real-Time Rendering

Finished Rendering

Finished Rendering

John and Max in Front of the Arctic Tern Mock-Up

John and Max in Front of the Arctic Tern Mock-Up

Get Involved

All of our 3D scanning equipment is available for use to students and researchers.  Click on our appointments page to sign up for a machine time slot, or contact us at for more information!

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