This discussion sparked an interest in me to figure out what decides the minimum flying speed of a kite in crosswind flight. I have defined the problem somewhat simplistically by saying that you donât want to stall when flying at the most vertical part of a loop. (I am still thinking about single kites on a tether.)

The results that came out were quite interesting. If the combined glide number of the kite and tether is around 5.2, the stall speed of the kite flying as an aeroplane should match the minimum windspeed for using it for AWE. The minimum windspeed will increase with better glide numbers, and vice versa.

Though this also means that itâs not easy to directly compare a 747 to a AWE kite, because you need to account for tether drag. But if you have a higher glide number for your 747 and then add tether until the glide number is 5.2, the two numbers should align. That being said, my equations show that minimal windspeed may be reduced to as much as 40% below stall speed, if the glide numbers are very high. OR you could say that a glide numer of 15 relative to 5.2 allows an extra 40% mass to be used while still maintaining minimum flying speed.

Furthermore, I ended up with the following equation:

w_{min}^2 \propto \frac{m}{C_L S}

This basically means that, very approximated and with many details left out, to maintain minimum windspeed for an AWE rig, when scaling, this ratio (mass to lift) must remain constant.

I believe for this kind of AWE rig, this metric is important and useful to describe minimum usable windspeed