Knyfe – Nyce project!
Please share the data with us.
:text-tmi:
Temperature
Attached is a temperature plot for the 10m planform area wing. The blue (lower=less wind needed for pull) lines are for air density for very cold dry air (23°F or -5°C = 1.13Kg/m³ @ Sea Level) and the red (upper=more wind needed for pull) line represents very hot dry air (105°F or 40.5°C = 1.32Kg/m³ @ Sea Level). The biggest difference is on the Sheeted-Out plot because lift efficiency is low so, more wind is needed to make up the difference in air density. Some numbers are:
50lbs of pull sheeted-out needs 1.7mph more wind for hot air (sheeted-in needs 0.8mph).
100lbs of pull sheeted-out needs 2.4mph more wind for hot air (sheeted-in needs 1.1mph).
150lbs of pull sheeted-out needs 2.9mph more wind for hot air (sheeted-in needs 1.4mph).
200lbs of pull sheeted-out needs 3.4mph more wind for hot air (sheeted-in needs 1.6mph).
250lbs of pull sheeted-out needs 3.8mph more wind for hot air (sheeted-in needs 1.8mph).
Altitude
Attached is an altitude plot for the 10m planform area wing. The green (lower) lines are for air density for sea level dry air (1.2Kg/m³ @68°F/20°C) and the purple (upper) line represents dry mountain air at 10,000ft/3048m (0.826Kg/m³ @ 68°F/20°C). To show only the altitude differences, the temperatures are held same but, note that would be a warm day that far up a mountain. Some numbers are:
50lbs of pull sheeted-out needs 2.6mph more wind for mountain air (sheeted-in needs 2.1mph).
100lbs of pull sheeted-out needs 3.7mph more wind for mountain air (sheeted-in needs 3.0mph).
150lbs of pull sheeted-out needs 4.5mph more wind for mountain air (sheeted-in needs 3.7mph).
200lbs of pull sheeted-out needs 5.2mph more wind for mountain air (sheeted-in needs 4.2mph).
250lbs of pull sheeted-out needs 5.9mph more wind for mountain air (sheeted-in needs 4.8mph).
Humidity
No plots needed for this one. Even for worst case (high temperature) Air Density only varies 0.3% between the full range of 0% and 100% humidity. Dryer air is denser (better for lift) than humid air, because water has less molecular mass than air. If it is raining, your kite will get heavier, and you will lose pull, otherwise humidity is really a non-factor.
Wind Gusts
Attached is a plot for gusts-vs-pull assuming 68°F/20°C dry sea level air at 60lbs of steady lift (17mph wind sheeted-out or 11.5mph sheeted-in). For simplicity it is assumed the wind gusts are in the same direction as the apparent wind seen by the kite (worst case). Actual gusts are generally in the true wind direction. The brown (upper) line represents when sheeted-out what gust speeds cause what additional pull. The pink (lower) line represents when sheeted-in what gust speeds cause what additional pull. This plot shows why it can be much more challenging to kite in gusty conditions. And, the lulls that accompany gusts add even more to the challenge (by reducing pull). This plot also illustrates that the effects of gusts/lulls are quite a bit more pronounced when sheeted-in. Some numbers are:
Sheeted-In
4mph gusts while sheeted-in sailing in 17mph winds adds 50lbs of pull
7mph gusts while sheeted-in sailing in 17mph winds adds 100lbs of pull
10mph gusts while sheeted-in sailing in 17mph winds adds 150lbs of pull
12mph gusts while sheeted-in sailing in 17mph winds adds 200lbs of pull
Sheeted-Out
6mph gusts while sheeted-in sailing in 17mph winds adds 50lbs of pull
11mph gusts while sheeted-in sailing in 17mph winds adds 100lbs of pull
15mph gusts while sheeted-in sailing in 17mph winds adds 150lbs of pull
19mph gusts while sheeted-in sailing in 17mph winds adds 200lbs of pull