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FrSky users, please read the readme.txt included in the ZIP
After almost 10 years there is a new . In 2010 Philip Kolb set off with the fineworx team to develop and build a new F3J plane with the latest available technology in aerodynamics, materials and building techniques. Those days no efforts were spared to create and find new ways of production, using the best materials available at that time. Due to that, PRESTIGE was not commercially available. The approach to build that glider did not reflect any reasonable economically based solution.
Nevertheless the PRESTIGE was probably the best allround thermal sailplane during that period of time and could excel in an astonishing wide range of wingloading. The glider performed marvellously from 1300gr to 5000gr flying weight (A 5kg version could win the XC-soaring competition in Montague 2014, although it was designed as an F3J plane).
Even nowadays, the almost 10 years old PRESTIGE would still perform as good as any of the modern F3J ships.
Fortunately by now, all the “latest and greatest technologies” from 9 years back (in-mould inflated fuselages, rohacell-core surfaces and wings, high modulus spread carbon technology…) found their way into model airsports and are well established and available for reasonable cost.
So why not taking PRESTIGE to the next level?
As F5J gained so much popularity over F3J out of various reasons during the last couple of years, instantly was meant to be designed for this new class.
Fundamentals of the design:
Since there is no towing in F5J, the structural challenge is significantly less than in F3J and the design parameters quite obviously are different. There is no need to design a light, stiff and strong spar. This by itself lowers the structural weight of the glider. As well the wings don’t need to be as thick as on an F3J glider out of the same reason – there is no need for a very strong spar to take the occurring high g-loads. In line with this, low flying weights and the resulting low Reynolds numbers call for the use of very thin airfoils.
Nevertheless, an F5J glider due to the rule set can be exposed to flying conditions from absolutely calm air to wind speeds up to 12m/s. For being competitive even in high wind conditions there is a definite need to be able to vary the wingloading of the glider no matter how sophisticated the aerodynamic design of the glider is.
Therefore great care was taken to optimize the design of PRESTIGE-2PK to perform over the whole range of possible flying conditions. Great emphasis was put on the fact that PRESTIGE-2PK actually can handle a lot of ballast very well. To achieve this goal the airfoils of the wing - even as they are very thin – need to be able to provide a high maximum lift coefficient. To achieve this goal a high (but not super high) aspect ratio wing showed best results, leaving sufficiently wide chords to optimize the airfoils for both, the low speed (low wingloading) case as well as the high speed (high wingloading) case. In the end the Aspect ratio came out to be 19.2 at 3.9m wingspan. To reduce induced drag with this fixed span the planform was optimized to be as elliptical as reasonably possible. It thereby features a relatively high taper ratio (this measure even helps to lower the weight and inertia in the outboard area of the wing and thereby achieve better manoeuvrability), which in return was counteracted by using a considerable amount of washout twist in the outboard wing panel to achieve docile stall characteristics and a minimal turn radius for thermaling.
Some content in menu 2.
Wing Area: 79.3 dm2
Aspect Ratio: 19.18
Surface Area: 86.63 dm2
FAI minimum weight: 1040g
Ballast capacity: up to 1400g
Wing section: PK-1162f (7.4%) - PK-1168f (6%)