Yeah, 11.2m2 swept area is the - doughnut
rotor was tilted at 25 deg… Top and bottom height uhhh kinda dunno…
AWE style power conversion efficiency, would take misalignment of rotor into account to indicate a smaller effective wind frontal area swept… it’s a cheat and a cop out and you should just use 11.2m2 as frontal area for normal wind power and sod you if you can’t make your flying wind turbine align to wind.
Main mast anemometer height is ~4.8m (from memory)
Control mast is quite a bit shorter.
from downwind and side
Fair point, I referred to the CP-λ curve as a power curve.
Here’s the same minute averaged data but broken into wind speeds as measured from the 2 different masts.
BTW - not gospel - this all needs a huge amount of checking.
Interested in AWES? Get on with it !
So given 6 wings was 1.2m2 the peak (minute average) power harvesting factor (ζ) in this test was 3.77
That’s 10X better than reported in the Kite Networks for Harvesting WInd Energy chapter in AWES Book 2
From some flappy, shabby, stringy foam toy wings
2.1. Spring–disc representation
A spring–disc model is developed for TRPT, assuming each ring within the TRPT is rigid. A single longitudinal section of the TRPT consists of two rings connected by six tethers equally spaced around the circumference of the rings. It is assumed that any force on the TRPT is shared equally among the tethers and that the tethers are straight, do not stretch and are of the same length. The six tethers in a single section can be represented by a single non–linear torsional spring. This model is adapted from analysis by Benhaïem and Schmehl [12].
The system is in equilibrium when the torque loss within the TRPT and the generator torque are equal to the rotor torque. For the current Daisy Kite design the equilibrium speeds occur at tip speed ratios of 1.2 and 5.3.
Amazing analysis by @Ollie
It explains how the early slow balance/~stall condition helped make some launches easier. (didn’t always work)
Having the rotor stalled before kick-starting, made it possible to hoist the turbine, let go of the tips, leaving it unattended under the lift kite, then move to the ground station where I could add a little rotary energy to kick-start the rotor into the generation speed range.
Occasionally to system ignored the initial slow balance/~stall phase and leapt into life… which is a bit scarier.
We used a startup brake method for launches after noticing this was sketchy
