The problem with crosswind flight for a Magnus rotor is the power consumption to spin the rotor. Indeed the tangential speed³ is the wind speed X the glide number (lift to drag ratio as simplification, generally between 2 and 3 for a high spin ratio) of the Magnus wing (that to obtain the apparent wind) X the spin ratio.
Power consumption (equation (3)) : 0.007 X 1 X 3.14 X 1.2/2 X 50.6³ = 1708 W.
Power harnessed: 2/27 X 1.2 X 1 X 1000 X 3.8 X (2.53)² = 2162 W before losses by cosine and by mass @tallakt includes in his calculations.
So it appears that for a Magnus rotor the higher apparent wind due to crosswind flight is the killer in regard to the required power consumption.
The turbosail was also seen as an alternative to the Flettner rotor. This is (in theory) a very high lift sail. I remember a lift coefficient of 6 but some problems of implementation occurred. Perhaps the turbosail can be a start for R&D for AWE wings.
For what I experimeted and and took into account analyzes in scientific publications (see the links above), rigid Magnus effect based rotors could be more efficient than inflatable ones and require less power consumption for an equivalent spin ratio.
Magnus / Flettner vertical cylindrical spinning sails have been tried for many years. As far as I am aware, they use more power than they save, because it takes energy to spin the sails.
It depends on the peripheral speed (reasonable power consumption until about 10 m/s for an inflatable cylinder, about 20 m/s for a rigid cylinder, see Fig. 13) of the balloon during the rotation. See the curves at 9:50 on the video below:
I re-read this chapter 12, and just noticed that the authors were referring to friction in the pulleys, pages 286 then 287.
Page 286:
We have noticed that friction in the pulleys is significant. The increase of mechanical friction forces is a well known physical phenomenon when scaling down.
Page 287:
Fig. 12.8 The measured
tension in the tether as a
function of the tether length r
for different angular speeds ω
of the Magnus rotor and tether
speed ˙r, for a wind speed
vw = 6.2 m/s. The zone A is
the possible force difference
that can be used to produce
energy. This zone is reduced
to zone B due to the pulleys
friction. This gives an idea
of the feasibility of a positive
power production cycle and
what one could potentially get
if this friction is reduced
