SLINGSBY T31 TANDEM TUTOR 5th SCALE

[chris williams]

As this model has stirred a little local interest, I thought a build log might be in order...

The process starts simply enough, with the slab sides constructed over the plan in the conventional manner before being joined together...

[Trevor]

Excellent. Thanks, Chris.

[chris williams]

The first looming obstacle is the setting up of the front wing centre section strut. F4 bears a great responsibility, carrying both the strut and the bracket for the front wing struts. Obviously, getting the correct height is essential for the wing's angle of attack, and the drawing was used as a template for setting it all up...
(Note: if installing a pilot in the rear seat, the slot needs considerable modification to allow room for his legs!)

[chris williams]

A few liteply alignment plates are used in order to (hopefully) keep the fuselage straight.

[chris williams]

The sheeting continues: note the apertures in the pylon to allow for the servo leads. Then it's time to start on the centre section

[chris williams]

The centre section has an ali bracket bolted to the front spars for attachment to the front fuselage strut, and the rear of the structure is filled with balsa to house the rear attachment bolt. The servo wires are installed inside the pylon to hide them as much as possible. In retrospect I would use a 10mm steel joiner bar at the front to ease the process of rigging...

[chris williams]

After finalising the lower sheeting, attention moves to the nose. Big mistake here, as the lead screwed to F1 was entirely unnecessary, rendering the model nose- heavy later in the build process!

[chris williams]

The tailplane is of simple construction and comes together quickly, at which point the wing centre section is ideally placed to check the all-important decalage, which should be at the usual 1.5 degrees...

[chris williams]

It was at this stage that the brass plate came unsoldered for the third time, so instead I went for a much simpler solution to the wing mounting bracket. A ply interior plate is held in place with two exterior 1.5mm ply plates and drilled through for the 3mm bolt.
When adding the fin, a vertical reference strip is added, to which the fin's centre line can be assessed...

[chris williams]

The wings are pretty straightforward, at least initially, with 3mm sq spruce spars, later doubled up in front of the web plates to form an I-beam. Of note is the much reduced area of the D section sheeting... The wings attach to the centre section with 13g piano wire front and back, although, as previously stated, a 10mm steel bar at the front would facilitate the rigging process...