The tail bracket looks there is some weight there?
Yes. The tail boom, inner boom and brace are about 30# (lbs).
Our original tail vane was SS, and it weighed about 20# not counting the strut, so we pretty quickly changed this to AL and that dropped about 7#. I'd say at this point we were furling at about 25 mph.
I've been using Hugh's updated method (below), but somehow I just botched the angle. The original design angle was supposed to be 19 degrees and we ended up closer to
29 degs. Oops. I'm aiming for a bit lower furling point and about 16 degrees now.
from Hugh's Windmill Wind Power Workshop
THRUST:
d (m) v (mps) kg # offset (in) offest (m) mkg ft#
4.572 ^2 9 ^2 33 51.31 113.1 9.5 0.2413 12.38 89.55
15 (ft) 20.1 (mph)
adjusted per Hugh's latest
RESTORING MOMENT:
boom
dia (in) #/ft l (ft) # kg moment (#')
2.5 2.004 7 14.0 lg boom 49.1
2 1.264 7.2 9.1 sml boom 59.2
2 1.264 5.5 7.0 brace 15.6
vane
ga sq ft #/sf
0.063 11 0.9 9.9 84.2
0.09 1.333333333 1.28 1.706666667 tot #' tot # CoG
(5052 AL .063" ~16ga, 41.7 18.91 208.0 41.7 5.0
strut is .090 AL ~13 GA)
angle (off vert) tan in m kg # mkg ft#
16 0.286745386 59.89 1.52 18.91 41.7 8.25 59.66
67%
#/kg 2.204622622
kg/# 0.45359237
cm/in 2.54
m/in 0.0254
mph/mps 2.236936292