Although it’s a large sailplane it’s pretty light, so the Aresti 108 will fly anything from the merest whiff to a howling gale, and with its large ballast capacity it can handle both situations very well. It is majestic in the air, has amazing energy retention and is has forgiving flight characteristics. Due to its size it looks as if it is flying very slowly, but don’t be fooled!
The optimized plan form puts the area where it’s needed most for precision aerobatics. The layout of the wings and fuselage provide ample room for ballast in both the fuselage as well as the wings. The fuselage volume is generous enough that any practical radio system can be used.
Originally designed as F3X type tailplane aerofoils, the sections have been refined to provide for maximum control response with minimum deflection and therefore drag; so the trade off is the infinitesimal increase in drag, offset by the increased control response using less deflection. At 10%, the fully symmetrical double cusped (Inverse sections top and bottom – like having undercamber AND “overcamber”) section is thick enough to give good aerobatic response, yet still carries a good ballast load and works well in sketchy air.
Large ailerons, large flaps and a semi elliptical wing planform each add to the overall performance of the airframe.The wings are a standard carbon reinforced hybrid layup, resulting in low weight and high strength. The control horns are factory installed and the result of a well thought out geometry that allows for flush servo installations using 10mm or thinner servos. A maximum servo thickness of 13mm in the flap bays and 12mm in the aileron pockets, allows the use of a wide range of servos. Conventional servo linkages provide a clean, practical and most importantly, serviceable, control installation.The geometry has been optimized to use full servo travel to achieve high torque and minimal slop. Optionally, LDS control systems can be used.
Sine Wave Spar:
Used in several military aircraft, the Sine Wave Spar has been adapted for the first time to make up the heart of a model sailplane wing. It has amazed us with its low weight, and ultra-high strength. Unlike a conventional spar, the Sine Wave Spar adds terrific torsional strength while weighing considerably less than the older non-optimized spar.
The beautifully contoured fuse is deep, and balanced front to back and provides the side area required for some aerobatic maneuvers. Carbon/Kevlar reinforcements provide the all important resilience to the boom and also allow the electronics bay to be 2.4GHz friendly. Access to the radio gear and ballast is provided through a conventional slide-on canopy. While the long nose accentuates the pretty lines of the fuselage it also provides plenty of internal volume allowing easier balance of the model without resorting to shoehorning lead in every nook and cranny!
Control rods or rear mounted direct servos can be used for Rudder/Elevator control. These are all positioned to take the ‘head scratching’ out of installing the radio gear and to allow the use of standard 19/20mm round ballast slugs, 8 of them if you need them. The full ballast load including both the wings and the fuselage weighs in at 1.5Kg.
The rudder has been designed large enough to be effective for both aerobatics and slow landing speeds. The wing stub fairings have pre-drilled location dowel holes as well as pre routed openings for the green Multiplex connectors.
This is a one section plane so as mentioned, the aerofoils were specifically designed for the tailplane and this time for maximum control response with minimum deflection. At 10%, the tail sailplane section is thicker than is the norm but the infinitesimal increase in drag is easily offset by the increased control response for less deflection. To further increase the efficiency, pitch control is accomplished by using an elevator. No wobbly all moving tail and the elevator is driven by either an optional ball raced bell crank from a servo in the fuse, or where ultimate control is required, a servo can be placed in a hatch through the fin to give solid elevator control. The tails remain removable for convenient transport or storage.
The Aresti 108 has a large impressive joiner! Massive is the only way to describe this part. High modulus carbon, it’s sized at 40 x 20mm – larger than any F3f plane - and can handle light acro DS.
|Wing area:||1.581 In/2 (102dm/2)|
|Controls||Ailerons, Flaps, Elevator, Rudder|
|Servos||Up to full size throughout|
|Fuse Ballast||9 x 20mm round slugs = 1.9Lb (860g)|
|Wing Ballast||20mm x 250mm rods in each wing = 3Lb|