Articles for januari 2020

Note: “Comparing starting torques – – – -” added

The note: “Comparing starting torques of constant chord and tapered blades” has been added at the bottom of the menu KD-reports. It appears to be true that rotors with constant chord blades have a somewhat lower starting torque coefficient than rotors with tapered blades if both have the same design tip speed ratio. However, constant chord blades use much less material and are much easier to manufacture.

This note has been cancelled and replaced by report KD 697.

KD 97 reviewed

Report KD 97 from 2002, in which Cq is determined for low values of lambda, has been reviewed. Typing errors have been removed and some references have been changed to more recent KD-reports.

KD 652 and KD 653 replaced by KD 693

Report KD 652 and KD 653 about the VIRYA-3.6 and the Polycord transmission have been replaced by report KD 693. The tittle of KD 693 is: Calculations executed for the 4-bladed rotor of the VIRYA-3.5 windmill (lambda design = 4, stainless steel blades) meant to drive a centrifugal pump through a Polycord transmission with an accelerating gear ratio 2.5 : 1 and a vertical shaft in the tower.

KD 285 reviewed

Report KD 285 about the Gö 711 airfoils has been reviewed. A new chapter 4 has been added in which the moment coefficient Cmh is given around point H which is lying at 0.3 * c from the airfoil nose and half way the blade thickness.

KD 463 reviewed

Report KD 463 in which the aerodynamic characteristics of four Gö airfoils are given, has been changed. The Cm0.2-alfa curve has been added to figure 14 about the Gö 623 airfoil. A new chapter 5 has been added and figure 15 out of this chapter gives the curves for the Gö 624 airfoil.