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The Pyramid – a TRPT Rethink

Rod Read, Tallak Tveide, Oliver Tulloch��at AWEC2021 on June 24 2022

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three kites

a TRPT shaft

a triangular bridle

a cartwheel

actively controlled kites provide constant tether tension and elevation angle control

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launch and land by rotating the cartwheel then reeling out tethers

the triangular bridle must grow and shrink

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system glide ratio including tether drag

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What if: We had a kite with zero drag?

Tether tension limited by the material tenacity

Only tether drag [no kite drag]

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target glide ratio 8:1

(better system glide ratio below line)

feasible operating points

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[glide ratios for kite only]

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same plot for any scale!

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the simulated power curve is made using a fairly accurate simulator with three crude representations of the Makani M600 wing

600 kW each in their architecture

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Makani rated power 1.8 MW

This is a mostly realistic configuration that is medium well tuned. The Makani wing has too low glide number and too high wingspan for the Pyramid, so an optimized design would be better than what we see. More power in higher winds is possible by thicker tether. Diameter is 22 mm and tether length 286 m here. Hub altitude approx tower height + 140 m. That hub height would match a 4.2 MW Vestas HAWT approximately.�

The simulator does not account for wake effects when nearing the Betz limit that we clearly are here.

```julia�let azimuth = 0.0, horiz = 0.0, vr = 13_000, lambda = 0.06, d = 0.022

plot_power_curves([

power_curve(config(october_kite(), c_d_fun_coeffs = [0, 1/20], d = d, l = vr * d, radius = 26*3), 3:0.25:20, azimuth, lambda, horiz)

, power_curve(config(october_kite(), c_d_fun_coeffs = [0, 1/20], d = d, l = vr * d, radius = 26*3), 3:0.25:7.5, azimuth, lambda * 0.6, horiz)

]...)

end

plot!([0, 20], [1800, 1800], lc = :black, lab = "", ls = :dash)�```

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using a TRPT with no rigid elements should be feasible, fairly simple and enable scaling huge

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for details of the calculations, the control algorithms of the kite, the simulator source code, and a super tether drag calculation, go to

https://github.com/tallakt/TRPTSim