The classification of current wind turbines into lift and drag devices stands because wind turbines predate AWES and are massively marketed unlike AWES.
So AWES have to adapt to current wind turbine classification, not the reverse.
So what is named as drag AWES (crosswind flygen kite, working according to a stationary swept area) should be named as lift AWES (flygen and also rotary kites) in order to correspond to lift-based (stationary swept area) HAWT, both having a (Betz) limit of 16/27, both being perpendicular to the wind flow, with the cosine correction for the kite.
By the same what is named as lift-based AWES (all yoyo systems, and working according to a swept area going downwind) should be named as drag AWES in order to correspond to drag-based Savonius-type turbines, both having a limit of 4/27, both having a swept area (the power blade for Savonius-type) going downwind, pushed by the wind.
The drag power expressed by M. Loyd is a secondary feature _ for secondary rotors _with respect to its lift-based stationary swept area feature. Certainly the slowdown of the wing by the turbine is equivalent to the loss of power during the reel-out phase, this in terms of efficiency by kite area, but not by swept area (16/27 vs 4/27). The concept of swept area should prevail over the concept of efficiency by kite area. The qualification of lift-based crosswind kite is possible but within the swept area which is stationary for flygen and some rotary kites, or going downwind for yoyo systems. See the sketch below:
It is not for nothing that recent publications increasingly deal with the swept area and the Betz limit unlike Loyd’ seminal publication. This paper corroborates all that I repeat about the lift (both lift-based HAWT and flygen) and drag (both Savonius-type and yoyo) systems, with the respective values of 16/27 and 4/27, and what the publication of M. Loyd does not mention.
So the terminology in Loyd’s paper and following publications should be modified in order to adapt to the existing terminology in current wind energy.
In a practical point of view, the evaluation by swept area is a very important step to determine the power/space use ratio which is a key for the viability of AWES. Yoyo systems are not advantaged for this concern, and moreover their drag-based swept area also results in slow reel-out motion which requires significant gear reduction, not to mention their intermittent production.