Kites & kiting

[Turtle]

While kitesurfing videos can be pretty vapid, the sport and technology itself is impressive.

...

I’m looking forward to learning to kiteboard, hopefully soon, before age makes me too fragile for it.

Well, I'm rather underwhelmed. We have pictures & descriptions elsewhere in the thread of the snow kiting and the carts. Motorcycle riders do 'amazing' stunts but I am just as underwhelmed. Guess I'm not much into thrill-seeking or thrill seekers in the death-defying genre. :shrug: Let us know how it goes for you if you give it a whirl.

[Turtle]

A friend brought to my attention a couple [relatively] new kite wind generators to my attention and they are well worth posting. Thanks friend!  I particularly like the Makani rig; it looks pretty robust and I was impressed by the size of the team and their enthusiasm in the video of their first commercial-scale flight posted just 1 month ago.

Maybe this will get my keister out to do some aerial photography.  

Here's a setup from Altaeros Energies:
Main page: Altaeros Enegies
Video(s):
https://www.youtube.com/watch?v=kldA4nWANA8

Makani main page: Energy Kites
Video(s):
https://www.youtube.com/watch?v=An8vtD1FDqs

[Turtle]

Took a couple kites down from storage, so that's a start. As I mentioned a couple years ago, I moved since last flying at a nearby schoolyard and now I will have to drive to get to a suitable flying field. Well, we will see what we will see.

 

Anyone else doing any kite flying these days?

[LaurieAG]

Makani main page: Energy Kites

Video(s):

https://www.youtube.com/watch?v=An8vtD1FDqs

 

These Makani guys look pretty serious (albeit with a non cloth kite) but the Altaeros BAT has its own built in (and already inflated) air bag around all the bits that spin.

 

But both systems generate power on a much larger scale than what you'd need for a single home/workshop.  

 

Incidentally Turtle, have you ever seen a Mylar skinned kite? A friend of mine had one around 25 years ago. Mylar might make the kite go faster but the ripstop nylon used in other kites has useful resistance qualities so they don't tend to fall out of the sky at the edges of the envelope.

[Turtle]

These Makani guys look pretty serious (albeit with a non cloth kite) but the Altaeros BAT has its own built in (and already inflated) air bag around all the bits that spin.

 

But both systems generate power on a much larger scale than what you'd need for a single home/workshop.  

 

Incidentally Turtle, have you ever seen a Mylar skinned kite? A friend of mine had one around 25 years ago. Mylar might make the kite go faster but the ripstop nylon used in other kites has useful resistance qualities so they don't tend to fall out of the sky at the edges of the envelope.

I was hoping you would show up Laurie. Yay!!

 

On the power, you could certainly scale down for whatever your needs. I imagine the Makani rig has a lot of electronics, but I like how they launch it by powering the propellers until it reaches operating altitude. The drawback on the BAT is you have to buy the helium, which ain't cheap.

 

I suspect one could hang generating propellers on a more conventional fabric kite and do well, particularly on a smaller scale for personal use.

 

I tried building some Mylar kites but found it tore when I sewed it & I couldn't find the right kind of glue to glue seams. However, I built a 7' Delta-Conyne with a survival blanket that has Mylar on one side and plastic on the other and it sewed just fine. It's a wonderful flyer! I call it Alida, which means small-winged one. I have flown it to 500 feet, though as we recently discussed the legal limit in US now appears to be 250 ft. without getting a waiver. Please don't tell on me! :lol:

Here's a couple shots of Alida. I put the Mylar side down so I could bounce lasers off it for an UFO effect. Again, please don't tell on me. Actually, since I am an alien, it's probably OK.

 

 

 

 

PS I have a video of the 500' Alida flight and if I can get into my Youtube account I'll upload it and post it here.

Edited July 13, 2017 by Turtle

[JMJones0424]

Oh my, there's been a massive failure of communication, Turtle!  Altaeros appears to me to be nothing more than a tethered lighter-than-air balloon with a wind generator attached.  As such, it is not a kite.  It seems to me that this design simply replaces the not insignificant infrastructure of a conventional windmill with a balloon and a tether.  There may be benefits for this, but this is not the technology that I wanted you to review.

 

I like the Makani design as it replaces the infrastructure of wind-powered generators with tethers and what is basically a glider with attached tiny wind generators.  However, what I'd really like feedback on is the idea presented by Kite Power Systems.

 

 

This system uses two kites that are each somewhat similar to ram-air parachutes that I am somewhat familiar with.  With even a small amount of wind, this type of kite can be manipulated to produce lift and draw out a cable.  Resistance is used to generate electricity.  The geometry of the second kite is manipulated so that it flies back to the origin, and the differential force on these two kites is what allows the generation of electricity.  As the second kite returns to the base station, the roles reverse to ensure continual power generation.

 

This is, to me, a novel approach for wind powered electricity generation, but I am incapable of determining the utility of such an approach.

Edited July 13, 2017 by JMJones0424

[Turtle]

Oh my, there's been a massive failure of communication, Turtle!

Whaaat!? Me misundercommunicate? :lol:

 

Altaeros appears to me to be nothing more than a tethered lighter-than-air balloon with a wind generator attached.  As such, it is not a kite.  It seems to me that this design simply replaces the not insignificant infrastructure of a conventional windmill with a balloon and a tether.  There may be benefits for this, but this is not the technology that I wanted you to review.

Thanks for the correction on your direction. Moreover I agree the Altaeros device is not a kite, rather a tethered balloon.

 

I like the Makani design as it replaces the infrastructure of wind-powered generators with tethers and what is basically a glider with attached tiny wind generators.

Here I will make a couple contestations. The Makani device is technically a kite, not a glider. Gliders fly free and Makani's machine is tethered. That it looks like a glider is inconsequential to this distinction. (Hargrave's box kites were actually glider designs meant to improve lift-to-drag ratios) As to 'tiny' wind generator, the design flown in the video is touted as a 600KW rig, though they say nothing about it actually generating power or how much in the video test. While not 'huge', I wouldn't call 600KW 'tiny'.

 

However, what I'd really like feedback on is the idea presented by Kite Power Systems.

 

 

This system uses two kites that are each somewhat similar to ram-air parachutes that I am somewhat familiar with.  With even a small amount of wind, this type of kite can be manipulated to produce lift and draw out a cable.  Resistance is used to generate electricity.  The geometry of the second kite is manipulated so that it flies back to the origin, and the differential force on these two kites is what allows the generation of electricity.  As the second kite returns to the base station, the roles reverse to ensure continual power generation.

 

This is, to me, a novel approach for wind powered electricity generation, but I am incapable of determining the utility of such an approach.

Not including this design when I posted on the others was an oversight on my part...OK, a boo-boo. :doh: I think the design is utile in a number of respects. The generator is on the ground so electical wires don't need to run up to the kite. (They don't appear to specify how the control box for changing the bridals is operated, whether on board computer, radio, or conductors along the flying line.) The kites themselves would be cheaper than the rigid body of the Makani machine, as well as safer if they fail and crash.

 

The one problem I see is in launching, where a suitably strong and stable wind would have to be blowing at the surface in order to get them up. Even if that wind is there to get a launch, people have been killed and seriously injured launching such multi-line large kites. (1983, Long Beach Washington; Steve Eidekin got a leg caught in a bridle line at launch, was hauled up around 100 ft, then promptly fell loose to his death.)

 

All-in-all, I agree it's a novel approach. I look forward to hearing news of any of these designs being put into service. Thanks for bringing this all to our attention.

 

PS Do you have and/or fly any kites?

[JMJones0424]

 Do you have and/or fly any kites?

I fly kites in the same way that people that make paper airplanes may consider themselves to be aeronautical engineers but clearly are not.  My go to kite is a simple delta wing.  The nieces and nephews usually don't have the patience required to overcome the lack of consistent wind direction in my area.  I tried making a tetrahedral kite with one niece out of straws, string, and tissue paper.  It flew well in consistent, low wind, but consistent wind is rare here, and the kite was far too fragile.  We discussed this long ago, here

 

This is all beside the point, though.  If a pair of ram-air parachute kites can provide consistent electricity for 300+ households, then this design provides more promise for carbon-neutral electricity in rural areas than anything I've come across so far.

Edited July 13, 2017 by JMJones0424

[Turtle]

I fly kites in the same way that people that make paper airplanes may consider themselves to be aeronautical engineers but clearly are not.  My go to kite is a simple delta wing.  The nieces and nephews usually don't have the patience required to overcome the lack of consistent wind direction in my area.  I tried making a tetrahedral kite with one niece out of straws, string, and tissue paper.  It flew well in consistent, low wind, but consistent wind is rare here, and the kite was far too fragile.  We discussed this long ago, here

Thanks for compensating for my sievish memory.

 

This is all beside the point, though.  If a pair of ram-air parachute kites can provide consistent electricity for 300+ households, then this design provides more promise for carbon-neutral electricity in rural areas than anything I've come across so far.

I think the kite power schemes are more tools in our toolbox of alternative energies. As you note in your remindence to me above, Texas winds aren't always consistent and this is true for any location. While winds at higher altitudes tend to be more consistent than winds at the surface, these high altitude winds also have their vagaries. Too light or in a calm, no fly. Too strong or gusty, poor flight and/or kite breakup. While conventional wind turbines can operate more or less autonomously, people will be required to be on hand to launch a power kite whenever the winds permit, mind it while in flight, and bring it down when the winds change to no-fly conditions. Certainly this condition of having folks on-hand would provide jobs, and what a fine occupation to be a kite-keeper!

 

To be a really effective tool, kite power plants will benefit the same as solar and conventional wind turbines from a suitable storage scheme. Folks are working on storage schemes such as batteries, pumped water, flywheels, etc., and these may all be viable tools depending on circumstances just as with the production of the power itself. Conceivably kite power could also be connected directly to a grid.

 

One final thought that just popped into my careenium, the ram kites operating a generator on the ground might be less likely to hurt any birds than the designs having propellers on high. Still, I suppose an angry raptor might become entangled in the bridal lines or get knocked senseless by the body of the kites as they wheel about.

[LaurieAG]

To be a really effective tool, kite power plants will benefit the same as solar and conventional wind turbines from a suitable storage scheme. Folks are working on storage schemes such as batteries, pumped water, flywheels, etc., and these may all be viable tools depending on circumstances just as with the production of the power itself. Conceivably kite power could also be connected directly to a grid.

 

One final thought that just popped into my careenium, the ram kites operating a generator on the ground might be less likely to hurt any birds than the designs having propellers on high. Still, I suppose an angry raptor might become entangled in the bridal lines or get knocked senseless by the body of the kites as they wheel about.

 

I can remember hearing a talk on the radio about 6 years ago, from a visiting US professor, who said that the problem with Australia's National Electricity Market (NEM) is that on average 45% of any states power is supplied by another state and of this power 63% is lost on average during transmission. He didn't mention batteries then but suggested that solar rooftop power should be made mandatory on new houses to reduce energy loss during transmission. Just as well the wind usually blows when the sun don't shine.

 

I would also like to see how much power was generated by the foil/ram kite based system over one complete cycle i.e. launch from ground then unwind to operating height then generate power then return to base. It would be interesting to see how long it has to run before it can generate enough power to reel itself back in safely.

 

While you can make power on the way out and up there by increasing the kites drag on the cable and you can minimise kite drag on the way in, the cable is not going to roll itself up (or tension itself) when the kite is coming in without using some sort of power. 

[Turtle]

I can remember hearing a talk on the radio about 6 years ago, from a visiting US professor, who said that the problem with Australia's National Electricity Market (NEM) is that on average 45% of any states power is supplied by another state and of this power 63% is lost on average during transmission. He didn't mention batteries then but suggested that solar rooftop power should be made mandatory on new houses to reduce energy loss during transmission. Just as well the wind usually blows when the sun don't shine.

Power generation and distribution is always a give-and-take proposition. :weather_storm:

I would also like to see how much power was generated by the foil/ram kite based system over one complete cycle i.e. launch from ground then unwind to operating height then generate power then return to base. It would be interesting to see how long it has to run before it can generate enough power to reel itself back in safely.

 

While you can make power on the way out and up there by increasing the kites drag on the cable and you can minimise kite drag on the way in, the cable is not going to roll itself up (or tension itself) when the kite is coming in without using some sort of power.

They say:

PHASE 2: RETRACTION (SEE KITE B )

The wing must be retracted to its start position consuming the minimum amount of energy. The pitch of the wing is actively changed to minimise aerodynamic force and the kite exits the loop to be held static in an overhead position to be glided back towards the starting point. Line tension can easily be reduced by a factor of 10 or more, such that a net energy gain is achieved over the Generation/Retraction reciprocating cycle.

So ratio of power generated to power used is at least 10 to 1.

[JMJones0424]

While winds at higher altitudes tend to be more consistent than winds at the surface, these high altitude winds also have their vagaries. Too light or in a calm, no fly. Too strong or gusty, poor flight and/or kite breakup. While conventional wind turbines can operate more or less autonomously, people will be required to be on hand to launch a power kite whenever the winds permit, mind it while in flight, and bring it down when the winds change to no-fly conditions. Certainly this condition of having folks on-hand would provide jobs, and what a fine occupation to be a kite-keeper!

This is where, if I understand the KPS system correctly, that we disagree.  I'm not sure that the Makani system must have human over-sight, though it seems reasonable to say such a thing.  I see the Makani system as a replacement for conventional wind-power generators.  However, in the absence of no air movement whatsoever, which I am not sure ever happens, I can't think of a reason why the KPS system can't be automated.  Perhaps I am misguided in analogizing the kites in the KPS system to ram-air parachutes.

 

Again, I defer to those such as you that are more knowledgeable than I.  I think we can agree that there is utility in locating the wind power generation on the ground rather than in the air.  What I am incapable of determining is the amount of differential force that this type of kite might be able to generate in different scenarios for a given size of kite.  Is consistent 500kW generation likely?.  Are the KPS claims simply false, or are they optimistic, or are they realistic?  I do not know, and I do not know how I can know.

[JMJones0424]

and of this power 63% is lost on average during transmission.

If this is accurate than the Australian power distribution system is ludicrously inefficient.  In the US, power loss through transmission lines is significantly lower, by a factor of ten.  https://en.wikipedia.org/wiki/Electric_power_transmission#Losses

 

 

 

Just as well the wind usually blows when the sun don't shine.

 You truly do live in an up-side down world when compared to where I am, as I find the exact opposite to be true.  Where I live, heat differential drives wind, so that the calmest winds, outside of storm fronts moving through, can be found in the late evening through to the early morning.

 

 

 

While you can make power on the way out and up there by increasing the kites drag on the cable and you can minimise kite drag on the way in, the cable is not going to roll itself up (or tension itself) when the kite is coming in without using some sort of power.

This was clearly answered in the video I posted.

Edited July 15, 2017 by JMJones0424

[Turtle]

 

While winds at higher altitudes tend to be more consistent than winds at the surface, these high altitude winds also have their vagaries. Too light or in a calm, no fly. Too strong or gusty, poor flight and/or kite breakup. While conventional wind turbines can operate more or less autonomously, people will be required to be on hand to launch a power kite whenever the winds permit, mind it while in flight, and bring it down when the winds change to no-fly conditions. Certainly this condition of having folks on-hand would provide jobs, and what a fine occupation to be a kite-keeper!

This is where, if I understand the KPS system correctly, that we disagree.  I'm not sure that the Makani system must have human over-sight, though it seems reasonable to say such a thing.  I see the Makani system as a replacement for conventional wind-power generators.  However, in the absence of no air movement whatsoever, which I am not sure ever happens, I can't think of a reason why the KPS system can't be automated.  Perhaps I am misguided in analogizing the kites in the KPS system to ram-air parachutes.

 

OK; did some more reading at KPS site. Apparently I overlooked some sections reached by the menu at the very top of their page. :doh: So, these kites have rigid frames and they say under the FAQ tab, "The KPS wing is a hybrid (i.e. fabric wing on a stiff structure to hold the aerodynamic shape), the wing does distort slightly when flying. This distortion will help shed ice, similar to a leading edge pneumatic inflation system on aircraft wings and propellers."

As to my kite-keeper they say, "Q: How many people do you need to operate the system?

 

A: The systems are totally autonomous, like a conventional wind turbine. For real time operation no manual intervention is required. However, the operation of all power generation systems is monitored, KPS arrays will be monitored remotely.

In the event of any fault or alarm condition, the affected system will send an alarm to the monitoring station."

 

Again, I defer to those such as you that are more knowledgeable than I.  I think we can agree that there is utility in locating the wind power generation on the ground rather than in the air.  What I am incapable of determining is the amount of differential force that this type of kite might be able to generate in different scenarios for a given size of kite.  Is consistent 500kW generation likely?.  Are the KPS claims simply false, or are they optimistic, or are they realistic?  I do not know, and I do not know how I can know.

I guess we have to take their words for it. Under the News tab for July, 2017 the new Chief Executive says, "Simon Heyes, Chief Executive said: “I’m delighted to be joining KPS; it’s an exciting time for everyone involved in the company. With the support of our investors, and with the talented people that we have working at KPS, we are in a strong position to develop and commercialise our technology. We intend to commence testing of our 500kW system later this year, and within 3-5 years we hope to deploy our first 3MW onshore and offshore kite systems. Our testing of our 40kW system is ongoing, and achieving performance above our expectations”.

 

The video (which was produced by Shell Oil and not KAP) says conventional wind power in the UK fell by 1% -even though more turbines went in- because the wind was less. I can't find much on the consistency of wind at higher altitudes. I imagine that making the determinations you ask about will have to come from actual testing as opposed to theoretical calculations, similar to how aeronautical engineers use wind tunnel tests to determine lift coefficients.

[Turtle]

Here's a Wiki page that has many references relating to kite power worth investigating. >> High-altitude wind power

High-altitude wind power (HAWP) is the harnessing of the power of winds high in the sky by use of tether and cable technology. An atlas of the high-altitude wind power resource has been prepared for all points on Earth.[1] A similar atlas of global assessment was developed at Joby Energy. The results were presented at the first annual Airborne Wind Energy Conference held at Stanford University by Airborne Wind Energy Consortium.

...

Contents

1 High-altitude wind for power purposes

2 Methods of capturing kinetic energy of high-altitude winds

2.1 Controls

 

3 Methods of converting the energy

3.1 Electric generator position in a HAWP system

3.2 Carousel generator

3.3 Aerostat-based HAWP

 

4 Non-airborne HAWP

5 HAWP Safety

6 Challenges of HAWP as an emerging industry

7 Early references to HAWP

8 See also

9 References

10 External links

10.1 Companies and solutions

...

High-altitude wind for power purposes

Winds at higher altitudes become steadier, more persistent, and of higher velocity. Because power available in wind increases as the cube of velocity (the velocity-cubed law),[8][9] assuming other parameters remaining the same, doubling a wind's velocity gives 23=8 times the power; tripling the velocity gives 33=27 times the available power. With steadier and more predictable winds, high-altitude wind has an advantage over wind near the ground. Being able to locate HAWP to effective altitudes and using the vertical dimension of airspace for wind farming brings further advantage using high-altitude winds for generating energy.

...

Here's some things on wind speed with varying altitude:

 

Wind gradient @ Wiki

In common usage, wind gradient, more specifically wind speed gradient[1] or wind velocity gradient,[2] or alternatively shear wind,[3] is the vertical gradient of the mean horizontal wind speed in the lower atmosphere.[4] It is the rate of increase of wind strength with unit increase in height above ground level.[5][6] In metric units, it is often measured in units of meters per second of speed, per kilometer of height (m/s/km), which reduces to the standard unit of shear rate, inverse seconds (s−1). ...

This paper from a study in Texas is referenced in the above article. >> Wind and Temperature Profile Characteristics From Observations on a 1400 ft. Tower Edited July 16, 2017 by Turtle

[Turtle]

In looking for info on winds at high altitudes I ran across maps and oodles of technology at a company called KiteGen. I searched the thread for the name and found I had mentioned the company way back in post #107. The article there was on a different scheme than they are using now, and what they have now is AWSOME!

 

It's somewhat similar to Kite Power Systems in having the generators on the ground and using a bowed kite, but otherwise far superior from what I can tell. See what you folks think...

 

Here's the main page for KiteGen: >> KiteGen Research

 

[LaurieAG]

It only uses the one kite too, with a more stable and simpler kite design as well.

 

25 years ago I made a tiny little (4x2.5 inch) delta wing kite out of bamboo tapers super glued to a small triangle of mylar. I made a little scale harness with 2 control strings about a foot long and taped these strings onto the side of a cowled personal fan. Once I had adjusted the strings to the correct length the little kite would fly in a continuous figure 8 pattern (skewed to one side) whenever the fan was turned on.