PuRES V2 2m

The Pures V2 is one of the original models that drove this class to worldwide success. The Pures V2 and the Slite V2 are probably the most highly regarded models in this 2m balsa glider class.

In 2011 Josef Gergetz of SETA Modelltechnik started to manufacture high quality sailplane kits for the newly emerging 2m build up glider competition class. By the end of 2017 the demand for Pures was so high that Josef Gergetz could no longer keep up with the production. Delivery times many months and it was decided to switch the production to lasercut technology at a larger manufacturer, resulting in the Pures V2.

The Pures V2 uses a slightly modified version of the highly regarded AG24 – AG26 airfoil family by Mark Drela. To allow accurate construction of the originally very thin trailing edge the rear of the airfoil was slightly thickened. It gives high lift with comparatively little drag over a wide range of lift coefficients (Cl). Compared to the Pures V2 the Pures V2 has improved L/D, especially at higher speeds.

The wing of the Pures V2 iis built as an open rib construction over very strong wound carbon fiber tube spars. To reduce sagging of the covering film between the ribs an extra sub rib is used between each full rib. This ensures the wing profile conforms much better to Mark Drela’s original airfoil than other built-up designs.

A balsa jig is supplied to ease positioning of the numerous ribs, ensuring the wing is built in an accurate and speedy manner. The laser cut structure is almost identical to the previous CNC version as there was nearly nothing to improve.

What is new? Besides the new lasercut production, the components are now numbered to ease building. Furthermore, there is an excellent multicolored construction plan and richly illustrated building instructions (in German only). Check out this excellent RC Groups build thread for good English language build info.

Wing construction
The optimised design uses wound carbon fiber spar tubes, a tapered tail boom and pultruded carbon fibre tubes for the leading edge. The Pures V2 has a three piece wing and is built as an open tubular spar rib construction. The wing joiner is made of 5mm class composite rod. The flat inner wing (with the central airbrake) has an a rectangular planform. The strongly tapered mid panels are joined to the center panel with a dihedral of 10°.The lightweight tip panel is joined to the mid panel with a dihedral of 16°.

Fuselage construction
The front of the fuselage is made from balsa with plywood reinforcements and plywood formers. Behind the wing, the wooden fuselage joins the CRP tail boom (wound, tapered carbon fiber spar tube) which is supplied already drilled for the V tail mounts and slots for the bowden tubes are also already milled out. The CRP tail boom is manufactured in the same way as the tubular carbon spars of the wings to similarly minimise weight and maximise stiffness. The fuselage is wide enough to fit a 4 x AAA sized NiMH (or similarly sized LiPo) battery.

Tailplane construction
The tailplane is quickly constructed from solid balsa sheets, with lightening holes shaping its Pures name.

Electric Modification
The Pures fuselage is 31 mm wide and 40mm high at the front. Major modifications would be required to fit an electric powertrain.

The kit consists of carefully selected and numbered laser cut balsa and plywood parts. All small parts and good quality linkages are included in the kit. RC components, glues and covering material are not included.

Pures V2 Specifications
Wing span	2.0 m	78 in
Wing area	36.0 dm2	558 sq in
Length	112 cm	44.1 in
Flying weight from	435 g	15.3 oz
Wing loading	12.1 g/dm2	4.0 oz/sq ft
Aspect ratio	11.0
Wing airfoil	AG24 mod / AG26 mod
Dihedral (EDA)	12.3º
Centre of Gravity	75-78 mm from wing leading edge
Controls	Rudder, elevator, spoilers

Pures V2 Typical Weights
Bare structure	300 g	10.6 oz
Covering	50 g	1.8 oz
Total structure	350 g	12.3 oz
Wiring	6 g	0.2 oz
Receiver	6 g	0.2 oz
Rudder servo	5 g	0.2 oz
Elevator servo	5 g	0.2 oz
Spoiler servo	5 g	0.2 oz
Battery	55 g	1.9 oz
Noseweight	3 g	0.1 oz
Flying weight	435 g	15.3 oz

Recommended RC
V tail servos	Ripmax SD100, Blue Bird BMS-101AMG, Blue Bird BMS-101DMG, Blue Bird BMS-101HV, Blue Bird BMS-A10H, KST X08, Graupner DES 427, Hitec HS-55, ES08
Spoiler servo	Ripmax SD100, Blue Bird BMS-101AMG, Blue Bird BMS-101DMG, Blue Bird BMS-101HV, Blue Bird BMS-A10V, ES08
Receiver	4 or 5 channel receiver to match your transmitter
Battery	HyperLipo 2S 300 mAh, Dream-Flight 300 mAh 4.8V NiMH, HyperFlight 650 mAh 4.8V NiMH, Dream-Flight 700 mAh 4.8V NiMH, 1S 2600 mAh Li-Ion cell.