Tuesday 8 July 2014

1.3m Twin-boom Pusher

Also called the Depron Spectre.

This was inspired by Alex Greve's (IBCrazy) EPP Specter designed for proximity and obstacle course FPV.

The twin boom configuration means the motor doesn't need to sit up high, which means the fuselage can be slimmer.

The forward swept wings give amazing anti-stall characteristics and increased grip in the turns. I suspect when the wing tips flex upward they give positive feedback to the turn, similar to snap flaps. A swept back wing would do the opposite. It also looks very cool in the air.

This plane can fly slow or fast and is crazy manoeuvrable even without movable rudders, and it can balance in it's tail.

The wing build is slightly different to my previous style, with cut out ailerons rather than full span. Wingspan is 1.3m or 53" compared to IBCrazy's 40" and 48" versions.

I made a 200mm (8") x 20mm flat bottomed airfoil in two 700mm halves, then cut a wedge from each inner end to make the forward sweep when glued and taped together. The tips are about 45mm forward of the root. I also cut wedges off the wingtips so they were parallel. Naturally I cut them the wrong way first.

I removed some of the forward former in the spar channel either side of the join so the Skyshark P4X spar had a wider bend curve.

Here it is in the air with 10-15kn wind

Wingspan - 1.3m (53")
Length - 80cm (32")
Airframe weight - 660g
Flying weight (2200mAh LiPo) - 850g
Motor - Turnigy 2822/14 1450kV (160W)
Prop - 7 x 4.5"
TGY 9018MG servos x 3

Depron Spectre plans and dimensions

Build overview video

UPDATE: Here are a two more recent Depron Spectre videos. Some aerobatics on a rare calm 13th Beach day and some slope soaring at Beacon Point in a lovely 10-15kn NW wind.