someAWE

Welcome MITxMakers!

New to Airborne Wind Energy? Want to know more?

Here are three youtube playlists for you:

10 Airborne Wind Energy introductions

Watch these if you still need to be convinced that AWE “Could be the magic bullet” for the world’s energy problem.


10 Airborne Wind Energy Systems

Watch these to get an overview about different concepts people are working on.


10 DIY Airborne Wind Energy Systems

Do you want to see more DIY Airborne Wind Energy Systems? Here are 10 projects to get you started. Some did not publish any source files - but if you ask the maker you might motivate them to share :)

 

Ready to make some Airborne Wind Energy yourself?

Want to be innovative and creative - with a purpose - while learning about many different disciplines (aerodynamics, mechanics, electrics, electronics, micro controllers) and along the way change the world? MAKE some AWE!

Here you can find more information about two Open Source Hardware projects I presented @ MITxMAKE:

AWEsome

An open-source test platform for airborne wind energy systems.

Pixhawk & ardupilot & new AWE flight modes & modified off-the-shelf model aircraft (Easy Star II)

The project files can be found in the AWEsome branch of Ardupilot on GitHub.

Note: AWEsome is brought to you by a great team from Universität Bonn and Humboldt-Universität zu Berlin. The project is sponsored by Daidalos Capital. I am not affiliated with the project or Daidalos Capital. I am however in close contact with the great people behind it: Philip Bechtle, Thomas Gehrmann, Christoph Sieg and Udo Zillmann and believe that this is so far the most promising open-source test platform for airborne wind energy systems. They are happy to answer any question you might have about the project - ping me if you need contact details. I will also update this post as soon as they have their own project website up.

Follow @someAWE_cb on Twitter to be notified when more info becomes available.

My Airborne Rotor

A passively controlled system with continuous power output and smaller airspace requirements using torsion and tensegrity.

The project files can be found here.

Questions? Feedback? Join the forum and ask!

Enjoy!
/cb     

MAKE some Airborne Wind Energy @ MITxMake!

AWE has the potential to provide cheaper and more reliable power than tower based wind turbines - by reaching stronger and more consistent wind with less material. The best design yet has to be found and many detail challenges have to be solved before we will see widespread adoption of AWE. A perfect playground for MAKERS!

That is why I have started to bring some Airborne Wind Energy to the Makers on a mission to let more smart and creative people know about AWE. Maybe some are looking for a project that is more than just educational or interesting but one that can change the world!

What better place to start than at the MIT and their MITxMAKE Makerfest?

 

There were 800 people attending – the feedback was amazing. Most had never heard about AWE or limited understanding on why it is so promising.

some Airborne Wind Energy booth at MIT x Make 2017

 

Enjoy!

/cb

 

My Airborne Rotor - Part 2: Making a MAR

If you want to build your own MAR - now you can :) See the first post for the design rationale. This post contains the Bill of Materials, the Original Design Files and step by step instructions.

Bill of Materials

 

Download BoM as PDF

 

Blade to hub connection

 

The Elbow

 

For transportability I want the blades to be easily separated from the hub. I also wanted to be able to adjust their pitch. I decided to go with a 3D printed connector that consists of two parts. The “Elbow” and the “RootPlug”. You can simply click here and have them printed. If you want to modify the design or print them using a different printer you can find and download the design in many different format here. Simply click “Export” by right clicking on the “Elbow”-Tab:

 

Since the uPrint at my Hackerspace is down I had them printed by Shapeways in nylon plastic.

Warning: Shapeways applied a “matte finish” to the parts that messes with the tolerances. The test print was fine but for the 4 production prints I had to scrape off some finish for the RootPlug to fit into the Elbow.

Things to know if you want to modify the Elbow  

If you want to modify the design it might help to understand the purpose of the different features. Make sure to read the comments in the design:

Why are there two fins/levers on the elbow?

Why do the CrossRod and the wing spars overlapp in the RootPlug?

 

Why is there a tooth missing?

 

Foam blades

 

 

The Blades are hot-wirecut from EPP foam, strutted with two spars and coated with film for stiffness. If you do not want to cut the blades yourself you can go to a CNC foam cut service like flyingfoam.com and use these order details:

Foam Type: 1.3# EPP

EPP Color: Black

Wing Span: 24

Airfoil: Other

Named Airfoil: fx63137sm

Chord: 6

Basic Options 1.3# EPP: Basic Options 1.3# EPP, Qty: 1,

Tube Hole: Front/Rear

Front Hole Diameter: 0.2

Front Hole Location: 1.55

Rear Hole Diameter: 0.2

Rear Hole Location: 2.05

Spar Slot: None

 

Blade assembly

 

Once you have your cores the assembly process is very simple:

  1. Glue in the spars (I used  Elmer's Super Fast Epoxy – but any epoxy glue should do - but TEST to see if it melts the foam)
  2. Apply the film coating – There are plenty of videos on youtube on how to apply “covering to a foam wing”. I used Hangar 9 Ultracote following  these instructions.
  3. Glue the short coupling pins into the RootPlug – these will hold the RootPlug in the Elbow via rubber bands.
  4. Glue the spars into the RootPlugs using epoxy glue.

The result should look something like this:

 

Notes on the picture:

  • I made some blades orange and some white for no good reason
  • If your blades and the film have the same width you will end up with uncovered ends because the film shrinks - no kidding...
  • The little black pin will hold the blade in the elbow via bungee cord

 

 Carbon fiber tubes

 

Order all your pultruded carbon tubes cut to length. If you need to cut them yourself please follow these instructions for cutting them with a rotary tool or a hand saw (some people take safety to the max :)

 

Final Assembly

 

  1. Glue the two HubCross rods into the HubCenter
  2. Glue the four Elbows to the ends of the HubCross rods.
    1. ATTENTION The four Elbows must be oriented exactly in one plane – use a jig to hold them in position during glueing.
    2. ATTENTION The rods must go all the way through the Elbow end must end in the front plane. 
  3. Glue HubStruts into the Elbows
  4. Add 2 bridle loops to each Elbow as connection points using Bridle Line.
    1. ATTENTION: Loop the bridle line around the Elbow! The fins are NOT designed to hold the entire tether force – they ONLY absorb some of the torsion forces from the blades.
  5. Add a loop of Shock Cord to each Elbow. These will be looped over the coupling pins when you stick in the blades.

Each Elbow should look like this now:

If you want to use your MAR suspended under a lifter kite like I did add bridle lines and the swivel:

ATTENTION: The red center line is VERY IMPORTANT. It absorbs the bending moments from the blades.

Done

Congratulations, your MAR is ready to fly. You can see how to use it in this video:

https://www.youtube.com/watch?v=S4mLAAnT21A

Please let me know if you have any questions, problems or suggested improvements to the design. 

Thank you and 

Enjoy!

/cb

 

 

 

My Airborne Rotor 1 - Part 1: Design rationale

The rotor I have built for this can be used for different kinds of airborne wind energy systems. Hence I have decided publish its design and to give it its own name:

MAR-1 / My Airborne Rotor 1

 

MAR-1 is open source hardware in accordance with the OSHW definition. Feel free to study, make or modify it or its design.

There will be two blog posts. This first one is about the MAR design. The second one will be about how to build a MAR.

Full disclosure: I am an engineer and maker - BUT I have worked in IT for the last quarter of a century hence: If you find any errors – I am sure there are some - or if you have suggestions PLEASE let me know!

Design decisions

Tip Rotor

Since the tips of a turbine make most of the power the inner part of the blades is mostly obsolete – especially if you do not need it as a structural component to keep the blades in the air or to transmit a force to a hub. You can think of a tip-rotor as an implementation of the "dancing kites" concept - with the kites being connected by a thin strut instead of a control algorithm :)

Number of blades

The smaller the number of rotor blades, the faster a wind turbine must rotate to extract the maximum power from the wind. I want to keep the rounds per minute (rpm) as low as possible – while avoiding gearing for the generator.

My 5-phase Falco generator reaches 150W at 120rpm – so we will work with 120rpm as the nominal speed:

 

For a small rotor this will lead to a small Tip Speed Ratio (TSR). If we use four blades we can achieve a decent efficiency (cp) with a TSR of 3:

Source FAO IRRIGATION AND DRAINAGE PAPER 43, Water lifting, by P.L. Fraenkel

With 2 rounds per second (rps / equals 120rpm) and a nominal wind speed of 10m/s we will need a rotor radius of 2.4m to reach that Tips Speed Ratio of 3:

 

Airfoil selection

With a short chord (6”) and a slow blade we will need an airfoil that works at low Reynolds numbers. I wanted to use the flyingfoam.com service for my blade cores. They can cut any airfoil from the UIUC Airfoil Coordinates Database. In that database I found and selected the FX 63-137 airfoil:

 

It has been specifically designed for low Reynolds number applications on small wind turbines by the UIUC Applied Aerodynamics group as part of their Low-Speed Airfoil Test program.

Summary

MAR-1 design parameters:

  • 10 m/s Wind Speed
  • 4 blades
  • 120 rpm
  • Rotor Radius: 2.4m
  • FX 63-137 airfoil

The next post will show you how to build your own :)

Enjoy 

/cb

Will it scale?

One (of many) key questions for all Airborne Wind Energy Systems is: Will it scale?

If the square-cube scaling law limits the size of conventional turbines, it will certainly limit the scaling of any airborne structure.

Here are some initial thoughts on scaling the OTS system up:

The Rotor:

The rotor is a rigid structure and the square-cube law will certainly apply. The most obvious way around it would be to stack multiple rotors. By stacking the scaling becomes linear. Twice the number of rotors will generate twice the power (ignoring shadowing effects) and have twice the weight.

The OTS transmission to the ground:

For the OTS scaling up in length and scaling up the transferred power have to be considered. Scaling up in length is linear. Twice the length will have twice the weight - under the assumption that the OTS weight can be ignored for its own dimensioning. This is true if the tether forces used for power transmission are large in relation to tether forces needed to support its own weight.

The current OTS weights 3.2 lb/100ft (50g/m). This is 1/100th of its strength or in other words if you scale it up to a length of 10,000 ft you would have to double its strength to support its own weight.

Do not try to power your space elevator with an OTS but for your AWE system you will be fine.

To double the power you can double the speed/rpm or double the torque. Doubling the torque as a first approximation will double the tether forces and double the buckling load on the struts.

I assumed that tether strength would scale linearly to its cross section and therefore its weight. When looking at specs you will see - for reasons I do not understand (yet :) - that strength growth faster than weight. If you are a tether experts, please enlighten me. But for now this brings us on the safe side.

The struts are Euler's columns type 1 (pivoted in both ends). If we want to double the allowable load we have to double our Moment of inertia. For a strut with a cylindrical cross section this is Ix = π (do4 - di4) / 64 . Weight will go squared with diameter while buckling force will go in forth power. Who cares about square-cube if you can beat it with square-forth power :)

Summary: According to my cocktail napkin calculations the OTS system should scale very nicely! But then again don't trust an engineer that has not engineered for a quarter of century! PLEASE correct me if I am wrong - I can handle public shaming :)

What I haven't considered in this calculation are drag based losses of the OTS. It is moving multiple tethers cross wind at high speed - so there will be losses that can not be ignored when scaling up. For now I lack the skill to simulate and the data to calculate. Anybody up for the challenge? If not I will have to take some data from my next version. Until then:

Enjoy!

/cb

Some data about the 250W OTS Airborne Wind Energy System

Dear all,

Some info about the system I flew on Friday.

The system is designed for 250W@10m/s - the total mass in the air is less than 1kg:

(To download file right click on TAB in OnShape and choose "download")

 

 It actually reached 140W before it broke due to the stupid way the OTS is connected to the generator...

I will publish updated design files soon (if you can't wait check them out here - but be carefull this is DRAFT)

Enjoy!

/cb

Update on the OTS design

Dear all,

Some have asked for an update on progress on the OTS design. Here you go:

After successfully flying this little proof of concept:

https://www.youtube.com/watch?v=CWeu8aI2ofw

I started to build and test a 250W version of the base station:

A 24inch diameter version of the "Open Tensegrity Shaft" (OTS):

(Design files for the assembly stand can be found here)

And a test bench to see if it holds the torque and RPMs:

https://youtu.be/5wu3bggTH5U

Now I am in the process of building a “TipTurbine”:

 

 

Since the tips of a turbine make most of the power - and with an OTS you do not need to transmit the force to the center of the hub - the inner part of the blades is mostely obsolete. This way the TipTurbine leverages the benefits of cross wind travelling wings without me having to be smart enough to build a flying robot and without having to pull the ground tether cross wind.

The lifter kite provides passive control by “telling” the turbine where is “up” and by fixing the center point of the circular “flightpath”. You can find the design files of the TipTurbine here.

I went with four blades as a compromise between a high enough Tip Speed Ratio, a high enough RPM to not need gearing for the generator and low enough RPM to limit air friction losses of the OTS. 

The design allows to use different rotor blades and to adjust their pitch angle. The first blades that I will test are currently being built by the great guys of Kitewinder. As soon as they arrive I am ready for the next Flugtag!

Once Rod starts small batch production of his DAISY I will make sure to snatch one up and hook it up too the OTS.

Reinhart, any progress on the single skin rotor?

That's all for now. Enjoy!

/cb

 

 

 

 

 

 

 

 

 

Evaluation Criteria for Airborne Wind Energy Systems

In theory there are thousands of ways to build an Airborne Wind Energy System. Makers, researchers and investors will want to down select and try to find the most promising approach to invest their time and money in. I have compiled a list of criteria that can help to do that. Thank you to all participants of the first AWEuC for your input!

Efficiency 

There is no lossless energy conversion or transmission. Even with the primary energy for an AWE system (kinetic energy in the wind) being free these losses still matter as a less efficient design will require a larger system to generate the same amount of electric energy - which leads to higher investment cost and land consumption. The better AWE system is the one with:

  • As few energy conversions as possible (losses multiply)
  • The highest efficiency for each of the conversions and transmissions


Reliability

An AWE system must operate with as few and as short shut downs caused by failures as possible. Lack of Reliability does not only impact availability and will reduce the capacity factor but will also require human intervention and might be a safety issue. The better AWE system is the one with:

  • The longest time between failure (MTBF)
  • The shortest time to repair (MTTR)
  • Operates reliably under the biggest amount of operating conditions


Availability

In addition to measuring its Capacity factor AWE systems have the potential to make power available at times and location where other sources are not or produce at a high Cost/kWh. The better AWE system is the one that has the

  • best transportability/mobility
  • best deployability
  • highest capacity factor


Complexity

A more complex system is more likely to fail by reaching a system state that it has not been designed for. While complexity is a subjective property there are many different models that try to make complexity comparable. The better AWE system is the one that has:

  • fewer components with fewer interconnections
  • favors passive over active components


Automatability

Human labor is expensive in relation to current energy prices. Every system state that requires human supervision or intervention will increase the Cost/kWh. For mainstream and/or off shore application an AWE system must be fully automated. The better AWE system is the one that

  • Has the higher degree of automation
  • Requires fewer human supervision
  • Requires fewer human intervention


Scalability

Square-cube law is a trap. As a body grows in size, its volume grows faster (cube) than its surface area (square). The mass of a body scales with its volume. The lift however scales with its surface area. Hence any AWE system that requires to scale up a (solid) body will reach a scaling limit. The better AWE system is the one that:

  • Does not have an airborne solid body that has to be scaled linearly with its power output
  • Has the higher scaling limit.


Airborne Mass

More mass aloft requires more lift and raises the risk for damage in case of system failure. Lift is not free and will reduce efficiency. The better AWE system is the one that requires less airborne mass.


Durability

System components like tethers and fabrics will have to be replaced frequently – reducing the capacity factor while increasing maintenance and material cost. The better AWE system is the one that

  • Limits wear especially on tether and fabric components
  • Has the longest times between component replacements
  • Has the lowest cost for components that need to be replaced frequently.


Ductility

Turbulence matters. Over speed protection is hard. Staying airborne when its calm can be hard too. The AWE system must be able to accommodate the widest possible range of these conditions. The best AWE system is the one that
Has a reliable overspeed protection

  • Can operate safely over the widest range of operating conditions
  • Can handle turbulence and other sudden changes in operating conditions best


Safety

An AWE system that cannot be operated safely will not be operated at all. With a lack of safety standards for AWE systems it is up the manufacturer to proof safety of its system. The better AWE system is the one that

  • Can be operated safely
  • Can PROVE that it is save


Potential

Factors like scaling limits, low operating altitudes, large land or airspace consumption, limited security, dependency on wind direction lower the maximum power potential of a design while transportability/mobility increase the potential in high energy cost markets. The better AWE system is the one with the

  • biggest potential

Cost

Cost/kWh is the ultimate success criteria. This is increased by manufacturing cost, development cost, material cost, maintenance and operating cost. A sufficiently good AWE system is the one that can produce electric energy at a significantly lower Cent/kWh than other sources in the same market. This price can vary significantly for off grid and remote production.

Investability

Developing a market ready AWE system requires a lot of time and capital. There is a high risk of losing 100% of the investment. Any AWE endeavor will have to acquire investors and keep them happy over a long time span. An AWE system is “Investable” if:

  • The investor can reasonably expect a very significant return on invest.
  • There is a way to keep ahead of the competition once the system is developed. E.g. by 
    • Patent protection (Many AWE patents are either expired or very weak given prior art)
    • IP protection – e.g. in the form of software/controller algorithms that are either not disclosed or covered by IP laws.
    • Be open but faster (shortest time to market) and better than the competition. The AWE sector will need multiple players to make sure that regulators, investors, insurances etc. accept it. Developing a market will be equally important as developing a product.

 

Did I miss any criteria? Next steps:

Make these criteria measurable and calculate/measure them for actual AWE Systems.

/cb

 

 

Proof of concept for an Airborne Wind Energy System based on an Open Tensegrity Shaft (OTS)

I didi it! I just made some Airborne Wind Energy. Some, not a lot :) Enjoy the first footage of a proof of concept for an Airborne Wind Energy System based on an "Open Tensegrity Shaft" (OTS). This demo uses a swivel caster with a 5" hard rubber wheel as a base that holds a bicycle dynamo hub with a power output of incredible 3W.

I will post some more details on this contraption and how I plan to scale it up during the next days. Now I need a drink.

Enjoy

/cb

 

Open Tensegrity Shafts: Mechanical power transmission using ultralight torsional rigid structures...

Dear all,

I have been busy finding a good way to get the power down from my rotor to the base station. I thought you might enjoy some of my findings - hence I give you:
 

Open Tensegrity Shafts

Mechanical power transmission using ultralight torsional rigid structures made of components in compression and tension.

Overview

Airborne wind energy systems with ground based generators require a mechanical power transmission to the ground. Currently multiple tether-pull based concepts are being investigated (e.g. by the Kite Power Research Group of TU Delft). Pull based concepts require a recuperation phase where the tether is being pulled back in and power is being consumed - not produced.

In today's technology torsion in a driveshafts is the most common method for continuous transfer of mechanical power. Hence looking into torsion based power transfer for Airborne Wind Energy (AWE) seems natural and has been suggested  by different sources (e.g. US 6616402 B2 or US8197179 B2 “continuous central driveshaft”). A conventional drive shaft however - even when build with modern materials like  carbon composites would likely be prohibitively heavy and cannot be easily retrieved.

Structures made of components in compression (struts) and tension (tethers) as an alternative to a central shaft have been proposed (e.g. US 5040948 A "Driver lines attached to the extremities of the turbines transmit this energy"  or US 8197179 B2 “a geometric mesh of interconnected struts” or US4708592 “edgewired turbine”).

This text aims to discuss some of these structures and their usability for Airborne Wind Energy application.
 

Definitions

Tensegrity [...], is a structural principle based on the use of isolated components in compression inside a net of continuous tension, in such a way that the compressed members (usually bars or struts) do not touch each other and the prestressed tensioned members (usually cables or tendons) delineate the system spatially.[1]
The term tensegrity was coined by Buckminster Fuller in the 1960s as a portmanteau of "tensional integrity".  [2]

Open Tensegrity will be used in this text for lack of a better term and for a structure that fulfills the definition of Tensegrity except for the "continuous tension" part. An Open Tensegrity structure allows for an external force to be applied to delineate the system spatially. In AWE this force would likely be a lift force generated by an airfoil.

Shaft/Driveshaft can be defined as “a long cylindrical rotating rod for the transmission of motive power in a machine”[3]. For the purpose of this text we will remove the "cylindrical" requirement. We define any rotating three-dimensional long structure for the transmission of power a Shaft.

Open Tensegrity Shaft / OTS Combining the definitions of “Open Tensegrity” and “Shaft” an OTS is defined as a rotating three-dimensional long structure made of components in compression (struts) and tension (tethers) for the torsion based transmission of power.
 

Open Tensegrity Shafts (OTS)

2-Tether OTS (OTS2)

 

A set of two tethers spaced by horizontal struts is the simplest possible OTS (Picture 1).

 

Picture 1: 2-Tether OTS

When twisted the tether force F_T shows two components. A tangential component F_W that will transfer torsion and an axial component F_A that stretches the OTS (Picture 2).

 

Picture 2: 2-Tether OTS2 - transmitting torsion

This method has been tested and shown to have a strong inherent tendency to hockle/tangle - as can be seen in this video:

 


When looking at the OTS2 from the top (Picture 3) the reason becomes obvious. A part of the tether force points in radial direction. As soon as the angle between the strut and the center line is not exactly 90 degrees the two combined forces F_R of both tethers create a turning moment causing the strut to “flip”.

 

 

Picture 3: 2-Tether OTS2 - Radial force causing taggling

 

F_R becomes smaller with a smaller angle between the struts which can be achieved by a bigger spacing between them. But this also decreases F_W/F_T and reduces thereby the actual torque that can be transmitted. In practice configurations that seemed sufficiently “flip-proof” could not transfer any meaningful torque at all.

 

Since in practice catenary sag and wind drag will always bend the OTS which will lead to the struts turning against the center line and ultimately flipping the OTS2 does not seem to be practically useful for application in AWE.

 

Ring-”OTS”

Using ring elements instead of struts has been proposed and successfully implemented by Rod Read [4]. The results look promising and the solution has the advantage of rotational symmetry and less likelihood of tangling. At the same time however the ring elements experience side loads which will likely lead to a higher system weight. You can see the rings in this video:

 

 

 

8-Tether OTS (OTS8)

Adding additional tethers that stabilize the structure can mitigate the tangling problem. The resulting structure (Picture 5) consists of two working tethers that do the actual power transfer (a, b). The working tethers take a shape that closely resembles a double Helix. These are the same lines present in the 2-Tether OTS. Two counter helices prevent the tangling (a’, b’) and four corner lines stabilise and extend the structure (c1-c4). The struts (S1, S2) are positioned in an angle of exactly 90 degree to each other (which makes S1 parallel to S3). The distance between two struts is slightly bigger than their length. This allows them to become parallel to each other when no force is applied - hence allows for flat and easy retrieval of the OTS8.


 

Picture 5: 8-Tether OTS


The resulting structure has a very high torsional rigidity and can continuously transfer power:

 

 

Conclusion

  1. An Open Tensegrity Shaft is a feasible method for continuous transfer of mechanical power.
  2. The OTS8 seems to sufficiently mitigate tangling issues of OTSs with fever tethers.

Next steps

  1. Efficiency: When using an OTS8 in an AWE system induced drag will lead to low elevation angles of the system and limited efficiency of the power transfer.
  2. Dynamic behaviour - vibrations and oscillations generated when e.g. by centrifugal forces when spinning an OTS8 around a bend centerline while being dampened by the wind need to be investigated. Since I lack the skills to model and simulate a system of this complexity I will take it to practical testing.
  3. Dimensioning and Scaling: Finding the optimal strut strength, spacing, rotational speed and  tether strenghts while scaling the OTS8 up to useful power levels and finding the  lowest possible kg/kW*m.  

Sources

[1] Gómez-Jáuregui, V (2010). Tensegrity Structures and their Application to Architecture. Servicio de Publicaciones Universidad de Cantabria, p.19. ISBN 8481025755.

[2] Swanson, RL (2013). "Biotensegrity: a unifying theory of biological architecture with applications to osteopathic practice, education, and research-a review and analysis". The Journal of the American Osteopathic Association 113 (1): 34–52. PMID 23329804

[3] https://www.google.com/webhp?sourceid=chrome-instant&ion=1&espv=2&ie=UTF-8#q=define%3A%20shaft

[4] http://windswept-and-interesting.co.uk/?p=533

Edits

 

  • 2016-03-10 Added patents US 6616402 B2 and US 5040948 (Thank you Dave and Doug for your input)

 

Comments

 

Thank you for all the feedback here, here and here. For convenience let me summarize/respond to some of the points:

  1. Patents: When I quote a patent it is not a comment on whether it is the most relevant on the topic or whether I believe it could or could not be challenged with prior art. It is only to document the state of the art. Many ideas in the AWE space have only been documented in the form of patents - most of them expire before anybody even tries to use them. I am into AWE for the fun, the kWh  and the bragging rights - not the dollars. Because patents are patient and the wind is not: When it comes to Airborne Wind Energy there are way too many patents and way to few kWh :) If you file for a patent chances are the only person getting richer is your attorney.
  2. What about other methods (e.g. loops, belts etc.)? Is OTS is the best power transfer for AWE? I do not know. I do not even know if it will be feasible in real world application at all. Many things can still go wrong - see the "Next steps" paragraph for things that might make me wish I had picked a different method. So far it looks promising and none of these points seem to be a roadblock:
    • No large-scale similarity cases (I agree with Rod: "We've never had a great engineering need for torsion tension before. Now we do."
    • square-cube mass scaling-limits

 


 

Hello again!

First of all thank you everybody for joining someAWE.org - I am excited to see so many of you interested in this project.

Second of all sorry for being quiet after the quick launch for AWEC2015 - I had to finish some old projects before I can now dedicate more time to AWE.

Third: Those of you who signed up during AWEC2015 might remember that I promised to raffle a GoPro between the first members. I am glad to announce the  lucky winner: Ed. He has received the camera and I hope he will post the first footage soon :)

Enjoy!

/cb

Welcome to someAWE!

Many people (well at least me :) were longing for a place to find valuable non biased information about Airborne Wind Energy and a place to have an open, friendly but strictly on topic discussion about it.

Since I could not find it I have created someAWE. If you like the idea: Join us now!

/cb