TurcoLoco wrote:I am thinking on using an kite to parcially power a small trawler. I know there are a lot of variables involved, but in theory, what size an inflateable hybrid kite with say 100 meter lines would have to be to extract roughly 100 HP in 15 to 20 knot winds? How does the simulator software avaliable calculate total power?

Thank You.

You don't need a simulator software. Only a calculator or a spreadsheet.

You've got the power, and it happens to be thrust force x speed through to water.

You didn't say at what speed the 100 hp are pushing your trawler.

If your engine is 100 hp, you are actually likely to use 1/3 of it at economy cruise.

Bear in mind that the actual transmitted power is the engine's power x the total efficiency (gear-prop etc..) of the order of .5 at the best)

Force, or lift of the wing is power / speed

Be coherent with the units: use W, N and m/s.

From the following classic formula, A, the area can be found.

L=1/2 ρ v^2 A CL

A=2 L / (ρ v^2 CL)

where

L is lift force, [N]

ρ is air density [kg/m3] about 1.2

v is true airspeed [m/s] about 7.5-10 m/s

A is planform area, or projected area of the kite [m^2] that's what you are after

CL is the lift coefficient, take 1 as a first approximation (a lot more if you take a foil

)

Allow for the component of the lift acting in the direction of the travel.

But assuming you are not going to work the kite to give extra power

.

That's for a start. Let us know how big will be your kite!