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Kite Power in Horsepower

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TurcoLoco
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Kite Power in Horsepower

Postby TurcoLoco » Sat Jan 01, 2011 10:36 pm

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.

gazxtreme
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Re: Kite Power in Horsepower

Postby gazxtreme » Sat Jan 01, 2011 11:08 pm

Here's a couple of links that may provide some info. Long long lines and very large kite seems to be the way forward. I personally think sled type kite would be simle but only any good an a downwind reach, NASA Parawing pulls like a train.

http://thefutureofthings.com/pod/1075/s ... ships.html
http://gcaptain.com/maritime/blog/kite-powered-ships

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alexrider
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Re: Kite Power in Horsepower

Postby alexrider » Sun Jan 02, 2011 1:26 am

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!

tomatkins
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Re: Kite Power in Horsepower

Postby tomatkins » Sun Jan 02, 2011 3:02 am

Here is my estimation...totally hypothetical, but let's see how it compares with the results of the calculations.

Method: We used to drag each other around on the lake with little boats and outboard motors, so I know how that feels. So, having tea-bagged in 15 knots on a 10 meter kite, I would relate the experience to being pulled by a 3 to 5 Horse Power Outboard Motor. So, I would estimate that 100 HP would be generated by a 300 to 500 Meter kite.

I guess you would have to figure out a way to make the monster do "figure 8's" to keep the power on.

Disclaimer: "Your actual mileage and horsepower may vary".


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