| A rare treat to see the Gloucester 'Skunk
works' take on the vintage pair. The orange flying wing is based on the De
Havilland Swallow, while the blue twin boom is tribute to the Sea Vixen.
In fact the 'Sea Vixen' has been flying for a few years and has been
the test bed for several ducted fan units. Last used to test the Harrier
power unit it has now been converted to twin fans.
Both model have exactly the same power set ups. The fans are Phase-3
EDF 3-blade units as used on the Phase 3 Phantom, motors are Hobby-lobby
Jet Screamer Fan Out runners with 21mm Adapter. The adapter moves the
motor back and into the air stream so it stays cooler. These motors
produce 4500 Kv (rpm/volt) and weigh a mere 1-3/4 oz each. On three cells
they run in excess of 40,000 rpm, they can be run on four cells taking the
rpm into the high 50,000 rpm range.
Power comes from a Flightmax 2200 mAh 3S1P 25C (X-Thin) battery, I
quite like these X-Thin cells as they seem to fit better in slim fuselages
than the more usual trend towards dumpy 2200 cells. As only three cells
are used a Castle Creations Phoenix 25 speed controller is more than
adequate for the task.
Each motor has it's own ESC and battery with just one ESC providing the
power for the radio. Both models are constructed from Depron and carbon
with only slight traces of wood. The Swallow being most recent is a
masterpiece of Depron, carbon, Kevlar, glass and polycarbonate moulding.
With both models having exactly the same power trains a test flight to
compare performance was needed. Following his 'sacking' from the 'Skunk
works' test pilot team due to a 'slight' mishap with the Chairman's Blade
XL (see April 2009 blog) Paul Gurr has been replaced by Lee, who was to
fly the Sea Vixen.
The performance of both models was very similar, though most agreed
that the Swallow was just faster in a straight line but lost speed to the
Sea Vixen in the turns. This is pretty much as expected with the drag
increasing rapidly on the flying wing as up elevator is introduced in the
turn.
Phil was briefed to get a formation shot, but as usual he wasn't paying
attention and only managed to get us going in opposite directions. |
