... yes I'm bored aka I'm at work :ticking:

Surely we could answer the question of kite pull and de-power etc, completely remove the anecdotal element and get good hard data by doing something like ...

... hooking the kite into a strain gauge (linked and monitored by a PC) in the middle of a wind tunnel and then fly it through a set of moves, recording and graphing the data?

No more dodgy "More low-end than yours!" claims ...?

But could we all agree on the parameters of the test. Then the question would be is your PC Operating system better than mine? And then......

I need to go to leave the office and go home, maybe I'll just stay and go to work from here. wait, I'm at work, so I guess I don't need to go home.

... uh?

It's easy ... same wind speed, sail the kite through the power zone - how much does it pull in ft-lbs or Nm or whatever? We get a power curve plotted :smug:

It can't be that easy, maybe we should put it to a vote.

How do you make sure that it flies through the same part of the power zone?

After all that and ya find out LEIs are better then what?

/emote turns snobdr's volume down to 0. :flaming:

Oh come on maven dont be a hater

Just helping everyone else out. Wouldn't want them all to have to adjust the volume individually, be a huge waste of time and effort. So can you send me some pics of that snowboard you said you had for me?

It sure is that easy.....



.... if you have a wind tunnel :o)

Make a robot to fly it from 3 to 9 ... or 9 to 3

I seem to remember in the late 80's in Europe there was a short fling with indoor windsurfer, either as a competition or display - hooj fans, hooj stadium thing ... solved! Bet they're going cheap and we'll get solar panels on the roof - it'll even be green! Ok solar panels not so good ... maybe a methane powered turbine? Give snobdr a case of beans

What I was thinking would be like a kite dyno with charts and stuff that we can REALLY go all anorak over :frog:

This would be much more fun for 2 guys to just head down the beach and back in buggies with different kites. Then do it again after trading kites. Voila, you have your empirical data.

Quote:

Originally posted by Kamikuza Make a robot to fly it from 3 to 9 ... or 9 to 3

http://www.youtube.com/watch?v=-bNvawAtraI

(for some reason, the inline video didn't work)

Hmmmm... we're going to need that harness in XXS... and some strain gauges.

Worried about the throw on the depower bar for such short arms.

Oh well... these are just challanges, not barriers.

:wee:

ATB,
Sam

BeamerBob's approach is the most fun. But because I'm a science nut - I design and buildl exhibits - I 'd go for something 'a bit' more objective. Don't think you need a wind tunnel, but for depower kites on a bar how about :

1)strain gauges on the front lines ( 1gauge for both lines) + 1 strain gauge at each back line.
2)anemometer at the kite to measure appraent wind (kite speed).
3)anemometer on a pole up off the ground a ways to measure true wind
4)gps to measure your velocity if you're moving.

All these have to be referenced to the same time frame and connected to a data logger via RF, then you could deduce any of the other values you need other than kite location (you wouldn't have any location info for the kite relative to the wind window - but if you were flying patterns like sines or fig 8's you might be able to deduce location by the accel/decel curves).

Easy peasey, no?

krumly

Krumly, I knew you would show up on this thread and I always value your posts.

It would be great to have real-time logging of that data to a single source.

With the near-real-time reporting of true wind speed and direction from the Weatherflow sensor on our beach, plus the often consistent coastal winds, we have the closest thing to a private wind tunnel. I've gone as far as taking compass bearings on my tire tracks, plotting it against true wind direction and GPS speed and trying to make something of it. then I realize "hey I suck at this" and consider it more productive to ponder it all over a beer.

What we need is an engineering grad student looking for a thesis. I would help set it all up and help with the needed gear. and watch while sipping my beer...

My vote is for the beer sipping method

ditto on the beer drinkin':wink2:

I was always fond of the principles of physics and aerodynamics. I took a physics class for a technical degree once. I found that the excitement was lost once you started doing fancy math calcs. Angus I'll help with any buggy riding, kite flying, and I can be a great partner filling, icing and carrying that cooler to the beach. Sounds like a fine Belgian would be in order here.

do we have to provide our own chair for the beer sipping ???

Sand makes a good beer drinking seat...

Quote:

Originally posted by mougl Sand makes a good beer drinking seat...

and it's not that far down either, for when you fall over.:roll:

while all you genius IQ's are doing your research,i'll be flying my kites--be sure to wave from your computers hahahahahah:wee:

While you're flying your kite I'll be erm stretching all the muscles in my wrist that no longer work and squeezing tennis balls so I can hold a cup of coffee :P oh and drinking beer with the other hand

See I knew if we applied enough brains we'd get it sorted out ...

I believe it's Honda that have a robot for dyno testing bikes - you're not thinking laterally enough :tumble: that robot is just a frame with a collection of servos and pistons in the right places - we don't need it to look human or what-not ... we need a wind tunnel to reduce the variables - Mother Nature is a fickle old bag ...

Sigh, I'm bored ... broken wrist is teh sucks

Quote:

Originally posted by kitejumper while all you genius IQ's are doing your research,i'll be flying my kites--be sure to wave from your computers hahahahahah:wee:

While u fly your kites, ill be drinking beer devising a scheme to get your blades!!! bwahahaha


Sorry to hear about the wrist Kam....good thing u can fly depower 1 handed?

if you can dew that kami you r a proz ^^:bouncy:

Angus -

Too cool you were working on keeping track of all that info. Yeah - consistent coastal winds would be A bonus 'cuz it would sure make making sense of all the info a lot easier if you weren't trying to compare it against wildly varying true wind speeds.

But - and I think Aaron/rudeboysaude would agree with me -learning to deal with gusty Minnesota winds just makes us better fliers. If someone designs a kite that excels in our conditions, then it's awesome in my book.

I have this really cool, user friendly Vernier data logger. A winter project is to get that rigged with a kitebar. Typical strain gauge mounting is a bit of a PITA and fragile. There must be a way to work one into some amsteel leaders that would be field tough, and beerproof.

krumly

Quote:

Originally posted by mougl Quote: Originally posted by kitejumper while all you genius IQ's are doing your research,i'll be flying my kites--be sure to wave from your computers hahahahahah:wee: While u fly your kites, ill be drinking beer devising a scheme to get your blades!!! bwahahaha

hahaha good one!! stay away from my blades

This is all just a day dream kind of thing - if money were no object what could we design and build to test kite power?

Quote:

Originally posted by quarterz if you can dew that kami you r a proz ^^:bouncy:

English man, English! ;-) Txt speek, yeesh.

Actually, there are a number of start-up companies working on the kite power thing right now.

I think the most promising efforts are directed toward reel mills, where the kite flies a pattern to generate apparent wind, pulling out line on a capstan to generate power on the reel out. Then it goes into a depower mode, and some of the energy is used to reel it back in for the next cycle.

Makani has been working on this, as has TUDelft in the Netherlands. They have ground based rigs to measure line tension. What seems really tricky is monitoring the location of the kite to adjust the canopy for optimum power generation and to be able to steer it at any point in the trajectory.

I've and flown several of my kites eyes closed for 5 minutes, and I have a pretty good sense of where the kite is at all times, but not 100% sure of exact location. Now imagine developing software and hardware to keep huge kites going unattended 24/7 in high altitude winds. Makes terrestrial turbine technology seem dirt simple.

A guy by the name of Andy Reid did an engineering internship with Peter Lynn in 2000 that involved measuring line loads and angles of attack for numerous traction kites (C-Quads, LEI C-kites, Arcs, Waterfoils). His report can be found here: http://www.kite-surf.com/download/andyreidskitetestreport.pd...

krumly