Alvaro wrote: ↑
Mon Jul 17, 2017 5:33 pm
The mast is right below the back foot.
Any comments before i get it to the lake are most welcome.
The strap mid distance is usually vertical above the (rectangular equivalent) Front wing Center of lift line (1)
My 5 minute MAC (2) method:
1- Measure the projected length of your half wingspan = Dhwspan
2- multiply Dhwspan by 0.53 = D (3)
3- paralel to fuselage, on the front wing, at a D distance from root chord (RC under fuselage is your origin) draw the MAC line on a piece of paint scotch tape.
4- Measure your MAC line length between leading edge and trailing edge. Multiply by .25 = Dqmac or quarter MAC.
5- Place a cross on your scotch tape at a Dqmac distance from leading edge = CLift or center of lift = Mid strap distance point
Make fuselage top surface perfectly horizontal using a level.
Elevate the Clift point vertically using a laser or make a plumb line go straight down to the Clift line
Let us know how it feels.
(1) which is a line going through a point at 30 to 33% of root chord (RC) from leading edge
(2) MAC stands for "Mean aerodynamic chord".
This MAC line is the chord of a virtual rectangular wing of identical surface that would have the same lift properties as your real elliptical one.
(3) The precise value is 0.528672 but for 1/2 Wspan of (say) 300mm, the difference is 0.4mm so 0.53 is perfect for a kitefoil