Exhaust - Cat Whisker

This blog covers the manufacture and installation of the faux Shorts T1 exhausts

Overview
The selection of the Battle of Britain paint scheme set the task to replicate the British Shorts T1 Tucano with the general approach that for a stand-off scale RC model but just bigger.!

One of its distinctive features is the cats whisker exhaust required to shoe horn in the 1100 hp turbine in place of the factory 750 hp.

This builders are styled to capture the feel not the overall size for drag reasons.

Manufacture
After looking at options it was decided to design a stylised exhaust and have it manufactured as two halves and then fit onto a flat board allowing it to be moulded over.

The model was created with Albire 3D software, exported and manufactured by Shapeways. On arrival they were inspected then sanded with 120 / 240 grit aluminium open cut paper .

Next they were covered with packaging tape before fixing them to a board covered with tape and a coat of Mr. Sheen.

Assembled exhaust and one half on former
The white former is to mark the cutout to
allow mounting to the underside of the fuselage

Seven [7] layers of 8 oz fiberglass was placed over a mold then coated with West System 105 epoxy / slow cure catalyst. Once all layers were wetted through, a cardboard squeeze was used to remove excess resin. This was allowed to pool at the base then cure for removal later. Once this shell was created before preparing the other side and once cured repeated the process.

The finished components were clipped together and once aligned the gap created by the radius at the edge's was filled with a mixture of epoxy / milled glass with a length of 50 mm fiberglass tape applied over the mixture and allowed to cure. Finally the waste was removed and joint sanded and any gaps filled with epoxy/milled glass, allowed to cure and sanded to final profile. 

The profile slip was fitted, profile marked and the stacks trimmed to suit the side profile and set aside.

A piece of styrene sheet was fixed to the underside of the fuselage to create a flange for stack fitment, covered with packaging tape and a spray of Mr Sheen. Seven [7] layers of cloth were applied to represent the flange, set aside to cure and another done for the opposite side.

Held for checking with carpet tape

The stack was positioned, aligned, perimeter marked then a mixture of 5 minute epoxy/milled glass applied to the top and bottom edge and the stack offered up to the flange.  With the stack held in position the excess was filleted and held in position for 5 minutes utill the mixture set up. The assembly was removed then a mixture of epoxy/milled glass/micro-balloons applied to the inside face via a hole cut through the backing plate. The mixture was filleted and set aside to cure. Finally  the flange was trimmed and sanded into its final profile. 

When completed the whole assembly was sprayed with plastic primer filler then coated with blade putty and allowed to dry. When dry it was sanded with a orbital sander fitted with a 80 grit disc then finished by hand with 120 grit. Once happy with the shape it was sprayed with spray putty and finish sanded.

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Happy dance..!