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Originally posted by Feyd And we wonder why there are no girls on this forum.....

Sorry about that :wow::ticking:

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But just to add to the cornfusion,

Is that some fancy intellectual hybrid cooking style? :puzzled:

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wha about friction or coefficient of friction? How does one quantify that and how can it be applied to your equation? Again using the ski/buggy example the buggy must sluff off some energy in the form of lateral friction loss. Even if the appearance is that it is heading in a straight line I'm sure there is some minor level of drift. A ski in the otherhand, on an ice surface with the right tune and right skier will not suffer from lateral drift and will act as if it is literally on rails. Never mind the energy loss involved with buggy frame flex, tire deflection or even variations of tire pressure or the effects that temperature has on that variable. And speaking of temp. Cold dense air vs. warm air as well a humidity probably have some role here as well?

The equation above is all high school physics. If you want to go into more detail it gets more complicated. (Read: I don't know and would have to look it up)

Ideally if you are testing this, you want to avoid any other effects on the system as much as possible. That is why I suggest that skis on ice or a buggy on a really hard surface are the best conditions, and it needs to be done at speeds where aerodynamic drag do not factor too much.

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Originally posted by pbc Now describe the gear that will allow that measurement. I think you'll need a pretty high sampling rate. Philip

We are only looking at a ballpark figure here anyway, so you could probably use data from a GPS and a wind meter, weigh the buggy and pilot. Errors from other factors will probably be much bigger than the margin for error in the GPS.

There is another way to come up with a power rating. Compare the acceleration/top speed of a vehicle with an engine of known horsepower. Ideally you would use the same vehicle with both the engine and the kite, and account for the engine weight when using the kite so both systems are the same weight and have the same drag.

I looked one afternoon to solve the riddle of kite to horsepower. It seems that the variables all change way to much. You have angle, drag (surface, rider weight etc) wind, barometric pressure, humidity. You also need to take into account kite weight,drag, AR, surface area. To sum it up the best answer I found was to simply fly my kites and learn where they work and don't work for the intended application. Physics is a complicated beast that its near impossible to give definite answers.

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Originally posted by DemBones Bob is correct. Power is more applicable to acceleration than speed.

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Originally posted by Streetrider56 Quote: Originally posted by DemBones Bob is correct. Power is more applicable to acceleration than speed. Yes he is. I was thinking of torque multipliers (trans & rears) when reading 0-60.

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Originally posted by shaggs2riches ...Physics is a complicated beast that its near impossible to give definite answers.

I can get answers. I just need better funding.

Maybe I should apply for grant...

Hit up a company or two and ask for R&D sponsorship. Would be hilarious to see a company turn around and start advertising their line-up in HP vs square meters. Maybe you can get a new kite or two outta the deal.

yea 1 of my points exactly...hp sells cars, you would think it would sell kites too.....marketers love that stuff, just ask Detroit....i think we all agree kites produce hp, no way around that... even fully depowered they have to just to stay in the air..... its only a measurement, how to take it again could be debated forever..so in trying to become nearer to aoxomoxoa my thoughts do go this way.... so im guessing w/out all the mathematics and mechanics that we could deduce that race kites will produce more hp under identical circumstances than less aggressive foils. maybe w/ a different set of circumstances they wouldn't, like when being put into a lifting situation where a boosty type foil would be king.....id like to think im throwing around a lot of hp when i fly, but i have no idea… it could be 5hp max and i wouldn't be all that surprised....but someday the Mfgs' are gonna throw a hp rating on their kites...jusayin

I dunno, its all so subjective. And it seems to me an expirienced rider doesn't need to know hp when considering a wing. Why do I need to know hp? I think a lot people are pretty comfortable with knowing PA and AR in regards to what to expect to get out of kite. And what that kite does for each individual can vary greatly.

That being the case, having a way to determine hp and listing it, to me doesn't really seem to be much use beyond just the coolness of knowing how much force is being generated.

To put this into perspective, I've never even heard a number for the force a kite applies to the pilot. This is a very simple number produce for some kites, and yet I've never seen it published.

Yet I can tell you how much load I need to have a good buggy session: Enough to fight me flying static. I recall Phree once writing, "You know it's going to be a good session when you hear the bar smack hard against the stopper."

We all have our measures the tell us when fun is imminent.

For me, minimum wind speed suggests the minimum PA for the kite. A bad surface mods that size up. Gustiness mods it down. If I can't reconcile the two, I don't launch. OK, truth is I do launch, but if I have to hit the safety I quit.

As to AR, I always go high. At the beach, I need to eek out every bit of upwind I can if I want to see the end of the island.

Philip