Dihedral setting

[calgoddard]

Kyle -

It sounds like you are referring to a wing with V dihedral. This is a common configuration in scale model airplanes, but it is not used very often when it comes to indoor stick duration models like Wright Stuff airplanes. This is probably due to the increased difficulty in mounting the wing posts and achieving a symmetrical relationship between each wing section and the wing posts. The Vanguard model that apparently meets the 2017 WS rules has a wing with V dihedral and uses a clever wingmount system made from laser cut parts.

All free flight airplanes need some form of dihedral to enable them to recover from a bank or tilt to one side. In other words, they need roll stability.

There are several ways to achieve the needed dihedral:

1) vertical tip plates on each end of a flat wing;
2) tip dihedral (an inclined outer wing section on each end of a flat wing);
3) polyhedral (the wing has at least four sections angled relative to each other); or
4) V dihedral (the wing has two sections which are angled relative to each other to form a shallow V).

All of the above forms of dihedral are effective in providing roll stability assuming the tip plates are correctly sized and that the dihedral breaks, angles and wing sections are appropriately sized. You wouldn't want the angle between the two wing sections to be 90 degrees, for example, in the case of a V dihedral wing. An angle of about 160 degrees between the two wing sections would be more appropriate for a 2017 WS airplane with V dihedral. In other words, each wing section would be angled about 10 degrees upwardly from horizontal. The precise angle is not critical. If you use V dihedral, copy the angle used in the Vanguard model assuming you make your wing so that its span is slightly less than the 45 cm maximum, as you should.

Polyhedral is rarely used on indoor rubber powered stick duration models. It is seen quite often in outdoor free flight models, particularly larger ones.

Tip plates for a WS airplane can easily be made from 1/32 inch sheet balsa. Jeff is correct - make sure the tip plates are parallel to each other. They should each extend perpendicular to the leading edge (LE) and trailing edge (TE) of the wing.

[Kyle_Guo]

Ok, thanks. I have no more questions regarding this topic