Attached is my review of building and flying the Hacker-Model Super Zoom XL.
First – I must state it is truly a great flaying model.
To demonstrate that – please refer to the following link to a short video-clip (Thanks to Omri Launger) demonstrating the hovering stability in a very high (12-15kt) wind:
http://www.youtube.com/watch?v=UmxGFYrYznA
Model design, building and material overall quality are very good, and far better than the well esteemed MS-Composit epp models.
Hits:
1. I especially liked the fuselage longerons – and the stiffening they provide – which makes the model fly very accurate compared to this brand of models.
2. The size – is also very good, as the large wing and the resulting low wing loading result in a very nice, effortless flying, and enable very mild usage of the throttle.
3. Another hit is the construction of the motor mount. Very smart and neat, yet a stiffening connection to the landing gear area is required – as described below
Yet – in order to surpass what I believe to be one of the leading EPP models to date – the TELINK YAK, I would recommend the following improvements:
First – for the setup I used (basic Chinese setup):
Motor:
TGY AerodriveXp SK Series 28-26 1000Kv / 240
ESC:
Otter 40A 2-3S Brushless ESC w/ 4A BEC (w/ G
Prop:
TP Slow Fly propeller 11x3.8
Battery:
ZIPPY Flightmax 1800mAh 3S1P 40C
Now – for my impressions and suggestions (have implemented most of the suggestions below with great success):
Structure:
1. Nose section appears to be too soft – suggest addition of two carbon strips bridging between the bottom support of the firewall, and the landing gear mount. This will prevent un desired flexing of this area in flight, and possible breaking on hard landings.
2. All control surfaces hinge line is prone to tear off very easily. Recommend addition of some segments of peel-ply or Kevlar cloth to be CA-glued on the tips of each control surface to reinforce it. I used CA hinges but they seem to be a little too rigid at the beginning.
3. Tail skid is to low – allowing the rudder to be damaged from the ground when landing/checking controls before flight. Suggest addition of a small flat segment of fiberglass / ABS to continue the bottom surface of the tail skid and serve as a leaf-spring tail support (I used 0.6 mm glass epoxy sheet).
Travel of controls:
1. Travel of ailerons and rudder is sufficient.
2. Travel of elevator is badly influenced by rudder horn and pushrod. Suggest rudder servo and rudder horn will be elevated by 15-20 mm upwards, and clearing a bigger opening in the rudder to allow elevator deflection to 50-55 degrees.
Flying:
1. Fuselage side surface is on the low side – hence requiring too much rudder for knife-edge flight - high angle relative to the ground and too much controls coupling. Suggest heightening the fuselage side profile by 10-15% to achieve larger lifting surface.
2. To reduce coupling – I mounted the battery relatively upfront, and above the fuselage longerons. Suggest a cavity shall be made in that place to direct modelers to the preferred battery location
