Digest

It is a nice idea, that could interest fellows also engaged in tethered AWE.

Just a short question: have you any idea how to forward safely the released and stochastic (free) moving-sinking tether to the ground?

I think, some hundreds of meters altitude is neither interesting nor economic. But e.g. 10,000 m altitude and the same length of the tether makes the above question to be serious.

Gabor

Asked: Just a short question: have you any idea how to forward safely the released and stochastic (free) moving-sinking tether to the ground?

At terminus above is a parachute; reeling in after release opens the chute; apparent wind in the reeling lets the line be brought back home.

It's OK.

What about a laddermill instead of getting down the tether every time the new IFO has reached the working altitude?

Gabor,

What Joe is really suggesting is a large class of hybrid IFO-Kite concepts; like a "kite-elevator" to bring IFOs to high altitude where they are released to harvest energy, and then land "fully charged". This might be economic even with lead batteries (!), far more workable than IFOs without kites and tethers. How exactly did you envision your IFOs getting from the ground to soaring heights? Would this involve slow "clawing" to painfully gain height? A kite "rope-tow" conveyor would win any race. IFOs could also discharge (supercaps) to kite-based conductor trunk-lines, and not have to return to the surface to cycle energy.

Since you reject tethers, and now low-altitude kite methods, a-priori, your seeing them as synergistic adjuncts to the IFO is difficult,

daveS

PS Those who design with tethers have no problem thinking about

Gabor: "What about a laddermill instead of getting down the tether every time the new IFO has reached the working altitude?"

A flaw of the early LadderMill* is that the down-side wings are not utilized and just add parasitic drag. If the wings instead constantly disconnect at the top for FF, they can descend fast to fast-charge, or linger aloft to slow-charge. A LadderMill downside might also convey aerogel-insulated dewars full of cryogenic fuels downward, well-constrained.

* The AWES Forum has evolved a horizontal-arch (more cross-wind) L adder-Mill concept, as another improved variant. TUDelft seems to have lost interest in LadderMills, except as a confusing trademark, even as the open-AWE world continues to develop the concepts.

CC BY NC SA

On Sunday, February 23, 2014 5:34 PM, Gabor Dobos <dobosg1@yahoo.com

A "lifted-top laddermill" can have the down-going wings hard working with negative lift even while the up-going wings are working with positive lift. The lifted top pulley is lifted by a kite-system above the ladder-loop section. Such laddermill is different from the loop that has down-going wings just feathered. The "lifted-top ladder system" has the groundgen being driving continuously in one direction with almost all of the sections of the loop working. The short sections moving over the top pulley and around the bottom pulley are not taking energy from the wind. There may be more than one pulley above to give spread at the top of the loop of wings. The same lifted-top laddermill could elevate other materials, personnel, gliders, IFOs, supplies, etc.

~ JoeF

On 2014-02-26 21:56, joefaust333@gmail.com wrote:

Thanks Joe,

among others, it was Taras' whose publications inspired me to think of the possibility of energy harvesting with an IFO. Knowing these papers, there can be no doubts regarding IFO-flight as well as its superior energy harvesting capability. Well, I wasted too much time convincing my opponents. I propose that they study Taras Kiceniuk' and others' work.

Good luck!

Gabor Dobos

https://groups.yahoo.com/neo/groups/AirborneWindEnergy/conversations/topics/13447

has some comparison studies between the two main branches of AWES. See the topic thread there.

Tall suggestion: When a shared post is mainly advancing untethered AWES, then post in our dedicated forum here. Respect the tethered focus of AWES forum; we have care for AWES in all its branches and aim to develop each branch with focus in two forum spaces. When comparison is strong in a post, then posting in either forum with good topic title would be appropriate. There is no need to try to hijack either space for the topic of the other of the two spaces. Each space's target systems will have niche applications special to its tethered or untethered quality.

Best,

~ JoeF

DSTWP welcome fifth member who adds an acronym for us relative to our forum here:

UFEHD

untehered flying energy harvesting devices

Welcome, Pierre !

On 2014-07-31 17:09, Pierre BENHAIEM pierre.benhaiem@orange.fr [AirborneWindEnergy] wrote:

Thanks JoeF for your invitation and your welcome!

PierreB

Dear Gabor,

For my example 50 m/s is the apparent air (the term "wind" I used is not exact) speed due to the speed of the glider. So here wind speed gradient should be something like 5 m/s if we consider glider speed is 10 times wind speed gradient. In my example L/D with turbine is 17, so a higher speed is perhaps possible. Such (5 m/s) wind speed gradient can exist far lower than in JetStream, for example in some limits (altitude 200 to 400 m) splitting 2 layers of disturbed (friction with ground and obstacles) wind from non or less disturbed wind. But 5 m/s seems to be a rather high value for low layers of atmosphere, what is your advice about it?Note I made the rough comparison with a conventional HAWT having a 3 m diameter rotor with wind speed = 5 m/s. Several references of glider speed should be studied:

glider speed with regard to the slowest wind
glider speed with regard to the fastest wind
glider speed with regard to the ground (potential or kinetic energy)

Furthering the better ways to pilot the wing. Note that competitions of dynamic soaring with RC gliders are made in slopes of a moutain, using both dynamic wind in the slope and no wind zone in the top. But to make energy this mode looks too dangerous; using wind gradient farer of ground looking better.

PierreB

I think for the moment it is better to take the aspect of harnessing wind energy under the form of studies of performances of the glider in some configurations of dynamic soaring, and considering studies of storage as another field with possible meeting later, even if topics about storage of DUSTWP have completely their place within both DSUTWP and AWES forums since DSUTWP are AWES.

So our glider has a (lipo or other type of) battery.

Interesting analysis on Dynamic Soaring of Sailplanes over Open Fields - Aerospace ...

"The effect of higher mass is consistent with prior studies indicating that high wing loading is beneficial to

dynamic soaring performance. The reason for this relates back to Fig. 1 which shows the main driver behind

dynamic soaring thrust. The longer a sailplane can penetrate into the wind, the more time there is for

dynamic soaring thrust to be produced and thereby increase the aircraft energy and sustain the perpetual

orbit."

So the weight of battery could be an advantage.

Now according to previous calculations (on some papers from Pr.M.Diehl) the drag of the turbine should be half of the drag of the whole glider. We can extend this estimation for un-tethered AWES.With the followind example:

"Table 4. Baseline Sailplane Characteristics for High-Altitude Dynamic Soaring

Parameter Value

15 kg (33.07 lb)

m/S

(W/S) 33.33 kg/m2 (109.23 oz/ft2)

3 m (9.58 ft)

0.9

D0 0.020

(

L/D)max 26.59"

So wing area is 0.45. The drag of added turbine should be 1/2 X 0.45 X 0.02 (L coefficient) X 1.2 (supposed air density) = 0.0054. So sewpt area of turbine is roughly 0.005 m², the diameter being 8 cm. With a relative wind speed of 50 m/s we can obtain 300 W.The same with a conventional turbine of which blade diameter is 3 m (corresponding to the span of the glider) for a wind speed of 5 m/s.

So the advantage is not obvious, but some studies are needed.

I do not see DSUTWP compete with conventional wind (the same for tethered AWES but for other reasons) at least for a next future,but DSUTWP can provide interesting applications as: model airplane, autonomous drone (the other option,with possibility of mix, being solar) for meteo, or surveillance, and why not transport later. DSUTWP should constitute a whole, at least for beginning.

PierreB

Dear Pierre,

I am pleased to see that somebody makes some simple calculations on DS.

Just a note for your calculations below. You are right in supposing the wind speed gradient to be about 50 1/s in an advantageous place in a JetStream (the place determined and the glider guided to it by e.g. Lidar measurements). But a DS-ing glider can reach an airspeed about 5-10 times of the gradient. Let us underestimate the possibilities and take only a multiplicator of 3. It is well within the borders of reality that the DSing glider's airspeed in the JetStream can be 150 m/s instead of 50 m/s.

If you will repeat your calculations with this new airspeed, I suppose you will find many more things to be "obvious" than before. By the way, this is an open forum. Please consider what you want to make "obvious" for those who still don't know it. (Remember of your previous posts: "How do we collaborate while still competing?")

Gabor Dobos

On 2014-08-02 12:44, Pierre BENHAIEM pierre.benhaiem@orange.fr [AirborneWindEnergy] wrote:

If each of we five post using the email address used to sign up for the group DSUTWP, then I set "Unmoderated" for all of us. But if one of us tries to send message to DSUTWP using an email address different from what was used to sign up as a member, then the message will get delayed until a moderator approves the message.

~ JoeF

Post that was in [AWES]:

benhaiemp

Today Pr.Gabor Dobos makes an important contribution by designing untethered flying energy harvesting devices as the the most probable winner of the

Message 1 of 8 , Jul 31

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Today Pr.Gabor Dobos makes an important contribution by designing "untethered flying energy harvesting devices" as the "the most probable winner of the debate".

Concerning the quotation of JohnO: "There is tension between conventional wind and tethered wing systems" GaborD wrote "there is a tendency (that is detectable also in your post) to forget about the most probable winner of the debate" . I would add there is no tension between conventional wind and tethered wing systems because conventional wind has the whole market, probably for some time.

I do not see tethered AWE compete with HAWT in scale-utility due to problems with tether: huge space used, limits of height, aerial circulation, potentially dangerous. These problems does not exist with untethered systems, being able to be a part of existing aviation,unlike tethered aviation. The potential is huge, but the ways must be studied. What sort of economy? Centralized economy? For individual?Prototypes can be made with existing drones with turbine and storage. Joe Faust has a great experience of gliders. Towards harnessing energy of thunderstorms with their huge updrafts? If it is the case studied UFEHD would harness energy where there no plane goes.

So I agree with GaborD for the future of AWE as UFEHD, or UAWE (Untethered Airborne Wind Energy) which should become the first subject of discussion on the present forum, tethered AWE being well represented by Tu Delft, Makani, and others having made prototypes next to next to which our prototypes are toys.

PierreB

=====================================

GaborD,

The expression you give as "untehered flying energy harvesting devices" seems more correct than "Untethered Airborne Wind Energy " I give on my precedent. Indeed is it really wind energy?

PierreB

========================================

Pierre BENHAIEM

After reading some informations on GaborD s joined patent it appears the device is an airborne wind energy using mainly wind gradient between two layers of

Message 3 of 8 , Jul 31AWES


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After reading some informations on GaborD's joined patent it appears the device is an airborne wind energy using mainly wind gradient between two layers of wind of different speeds, flying in dynamic soaring mode like an albatros. Updrafts are also used.

My idea is such a device makes high technological challenges as storage in first, but has no inherent difficulties tethered AWE has due to the length of tether at low angle.

PierreB

=================================

On 2014-07-31 15:30, Pierre BENHAIEM pierre.benhaiem@orange.fr
[AirborneWindEnergy] wrote:

==============================

Thanks for the answer Gabor. I had the question because in beginning I imagined the following schema of flight: using updrafts then gliding, so only vertical wind. But it seems the main way is by using wind gradient, so horizontal wind. Please have you a representation of flight and some elements of calculation?

PierreB

===========================

AWES has significant branches by way tether or not distinction. When a post is advancing with focus the UFEHD or DSUTWP , then it is urged that such development be done in the space of

Dynamic Soaring UnTethered Wind Power


			Dynamic Soaring UnTethered Wind Power Mining the atmosphere for energy using aircraft mostly in dynamic soaring mode without conventional kiting tethering to the ground is the focus of this public discu...
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The present AWES forum would then remain with development for the tethered branch of airborne wind energy. Of course, when a post deals strongly for comparisons of the two branches, then such would be appropriate for either forum space in a well-designed topic design to help distinctions for readers and researchers.

Without conclusionary prejudice we aim to develop both branches of airborne wind energy. Hopefully all will cooperate so that reverence and expectations may flow smoothly. When one receives in one's email a post from AWES forum (this present forum) then one could expect that tethers are involved. And when one receives in one's email (if signed up for receiving posts from DSUTWP forum) a post from DSUTWP, then one could have on an "un-tethered" mental hat.

Some researchers and developers will ever be focused solely on tethered AWES. Others might be focused solely on untethered AWES. In time strong comparative testing will find niche-application winning systems in both branches of AWES. As for LCOE at utility scale, we are very far from knowing which branch will win over the other. Early declarations without proof as to the ultimate values of the two branches relative to each other and relative to other RE methods are poor foundations for any effort to alter the main focus of each forum space.

Thanks for any effort to keep the DSUTWP forum as holder of its related matters; thanks for any effort to keep AWES forum herein with the tethered-branch matters. DSUTWP has four members right now. AWES herein has 180 members right now.

Other perspectives?

Lift,

~JoeF

=====================================

Pierre B. has been formally invited to join DSUTWP forum.

If he joins that forum, then every post received from that forum should have an untethered AWES focus. ~JoeF

=================================

Thanks JoeF for your invitation I accepted with pleasure.

PierreB

======================================

Please aim to refrain from double posting or posting DSUTWP

matter in the other forum. Thanks.

======================================

Gabor Dobos

Thanks Doug! Atmospheric waves are attractive occurrences of the atmosphere from an energetic point of view. They have been well known for a long time. (e.g.

Thanks Doug!

Atmospheric waves are attractive occurrences of the atmosphere from an energetic point of view. They have been well known for a long time. (e.g. "Rossby- waves.) Our IFOs will probably not follow them to altitudes like 90000 feet, because of several reasons.
Gabor Dobos

========================================================

Joe Faust

Aug 1 10:05 PM

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Please develop DSUTWP methods in the group DSUTWP.
The tether systems are invited to be developed in the herein forum.
It may become disturbing to tag every post of the tether-develping
space with such as "non-tether will be better than tether" (my
characterization of the possible story that could unfold). Let each
branch of AWES go for its best unfolding. What may be "obvious" to
one party may not be "obvious" to another; also, some developers
simply are developing niche matters that are tethered or untethered;
those niche realms that are dedicated to tethers simply are
un-untethered, that is, tethered. Those niche reals that are dedicated
to untethered systems ... simply do not use tethers.
Energy storage is a special realm in itself. There are forums
specializing in energy storage development.
At the intro info page of this group herein, we point to the
branch of untethered AWES being addressed in group DSUTWP. The
tether branch of the AWE world is advancing the assets of tethers.
The un-tether branch of the AWE world is developing ways and means
without the use of tethers. The mind tack split: tether sets or
non-tethers is thought to be a chance to have two forums, one for each
split. Some common concerns will occur, but a great deal of focus in
each realm is suspected to be needed for grand successes. Please
consider keeping the focus of the two groups on the suggested bent.
In the far ends, there will be data to compare systems. We are
far from being mature; barely born and so much left yet to do ....
Have the two workshops grow as they might. It is suggested that each
baby grow in distinct cribs.

Best,
~ JoeF

On 7/31/14, Gabor Dobos dobosg001@yahoo.com [AirborneWindEnergy]
<AirborneWindEnergy@yahoogroups.com

Dear Pierre,

Thank you for your answer and forgive my oversight.

I have also formerly quoted Sukumar and Selig's paper in the Forum. It seems to be a basic publication in this topic. That gliders can use the small gradients near the ground or the surface of the water is a significant contribution to the topic. I have not evaluated this possibility yet from an economic point of view, but it is worth doing so.

You have asked me whether I have "a representation of flight and some elements of calculation?" Well, flight mechanics and dynamics of DS have been well known for a long time. One can find enough data about it on the net. The mathematical implementation of DSing flight in a simplified case does not need a complex mathematical background. Several years ago, I was lazy enough to write a small Pascal program (for DaveL: a small time-domain simulation) instead of using an Excel table for calculating manually each phase of the flight. I used this small program to simulate the flight of RC gliders, acquiring some parameters of the gliders and the flight from the net. The conformity was surprisingly and unexpectedly good.

Furthermore, I applied this small program to map the effect of several parameters of the glider and the flight on the possible energy output. There is an interesting fit between a data cited by you from M. Diehl and my simulation from many years ago. Well, when launching a glider in DS, the airspeed follows a saturation curve dependent on the number of DSing cycles as shown in the following fig :

As you can see, the first 4-7 cycles result in a very steep rise of the airspeed. If you consider that the kinetic energy is a quadratic function of the airspeed, in the 4th DSing cycle the rise of kinetic energy is about 35%. After each subsequent cycle, this energy enhancement can be taken away and the cycle can be repeted again and again, while the airspeed of the glider at the start of the repeated 4th cycle remains the same. This way, a steady state can be reached, producing in every cycle the same amount of surplus energy. Taking away this energy can be done by means of a propeller that is mounted on the shaft of an electric (motor)generator. Consider that in unloaded gear the drag of the free rotating prop is not a large value. In case of breaking the motion of the prop by means of loading the generator by charging a batterypack with its current, the drag enhances in sync with the removal of energy.

That's for today, all the best,

Gabor

On 2014-08-02 18:16, Pierre BENHAIEM pierre.benhaiem@orange.fr [DSUTWP] wrote:

Dear Gabor,

By my very rough calculations,like I write on my precedent post,I obtain something similar between DSUTWP and conventional wind energy : for span of glider = diameter of rotor, we have the same power for the same value of respectively wind gradient speed and wind speed. Please what do you think about this possible similarity, does it look correct?

I think a next step would be to implement a turbine with a battery on a glider like it www.youtube.com/watch?v=rfoxjNg-eg0 .

PierreB

This is the last post. Posting has been prohibited in this group. We will close the group once the messages are folded over into airbornewindenergy group.

Please post in other group with sharp topic titles. Thanks.

Experiment of split groups is over.

Best,

Lift,

~JoeF

Group: DSUTWP	Message: 51	From: Gabor Dobos	Date: 2/23/2014
Subject: Re: Tether up, then release to untethered phase. Then drive on board

Group: DSUTWP	Message: 52	From: joe_f_90032	Date: 2/23/2014
Subject: Re: Tether up, then release to untethered phase. Then drive on board

Group: DSUTWP	Message: 53	From: Gabor Dobos	Date: 2/23/2014
Subject: Re: Tether up, then release to untethered phase. Then drive on board

Group: DSUTWP	Message: 54	From: dave santos	Date: 2/26/2014
Subject: Re: Tether up, then release to untethered phase. Then drive on board

Group: DSUTWP	Message: 55	From: dave santos	Date: 2/26/2014
Subject: Re: Tether up, then release to untethered phase. Then drive on board

Group: DSUTWP	Message: 56	From: joe_f_90032	Date: 2/26/2014
Subject: Re: Tether up, then release to untethered phase. Then drive on board

Group: DSUTWP	Message: 57	From: Gabor Dobos	Date: 2/26/2014
Subject: Re: Tether up, then release to untethered phase. Then drive on board

Group: DSUTWP	Message: 58	From: Gabor Dobos	Date: 3/31/2014
Subject: System Enables Unmanned Aircraft to Detect Another in Flight --- Det

Group: DSUTWP	Message: 59	From: joe_f_90032	Date: 4/14/2014
Subject: Soaring Sink Calculations by Taras Kiceniuk in 2001

Group: DSUTWP	Message: 60	From: Gabor Dobos	Date: 4/26/2014
Subject: Re: Soaring Sink Calculations by Taras Kiceniuk in 2001

Group: DSUTWP	Message: 61	From: joe_f_90032	Date: 4/26/2014
Subject: Cryogenic Society

Group: DSUTWP	Message: 62	From: joe_f_90032	Date: 7/31/2014
Subject: Comparisons of tethered vs untethered AWES

Group: DSUTWP	Message: 63	From: Joe Faust	Date: 7/31/2014
Subject: Welcome Fifth Member!

Group: DSUTWP	Message: 64	From: Gabor Dobos	Date: 8/1/2014
Subject: Re: [AWES] Strategies for untethered flying energy harvesting device

Group: DSUTWP	Message: 65	From: Pierre BENHAIEM	Date: 8/1/2014
Subject: Re: Welcome Fifth Member!

Group: DSUTWP	Message: 66	From: Pierre BENHAIEM	Date: 8/2/2014
Subject: Re: [AWES] Strategies for untethered flying energy harvesting device

Group: DSUTWP	Message: 67	From: Pierre BENHAIEM	Date: 8/2/2014
Subject: Re: [AWES] Strategies for untethered flying energy harvesting device

Group: DSUTWP	Message: 68	From: Gabor Dobos	Date: 8/2/2014
Subject: Re: [AWES] Strategies for untethered flying energy harvesting device

Group: DSUTWP	Message: 69	From: joe_f_90032	Date: 8/2/2014
Subject: Group management

Group: DSUTWP	Message: 70	From: joe_f_90032	Date: 8/2/2014
Subject: Re: [AWES] Strategies for untethered flying energy harvesting device

Group: DSUTWP	Message: 71	From: joe_f_90032	Date: 8/2/2014
Subject: Perlan

Group: DSUTWP	Message: 72	From: joe_f_90032	Date: 8/2/2014
Subject: Posts that were elsewhere.

Group: DSUTWP	Message: 73	From: Gabor Dobos	Date: 8/3/2014
Subject: Re: [AWES] Strategies for untethered flying energy harvesting device

Group: DSUTWP	Message: 74	From: Pierre BENHAIEM	Date: 8/3/2014
Subject: Re: [AWES] Strategies for untethered flying energy harvesting device

Group: DSUTWP	Message: 75	From: joe_f_90032	Date: 8/3/2014
Subject: This group is folding into group airbornewindenergy

Group: DSUTWP	Message: 51	From: Gabor Dobos	Date: 2/23/2014
Subject: Re: Tether up, then release to untethered phase. Then drive on board

Group: DSUTWP	Message: 52	From: joe_f_90032	Date: 2/23/2014
Subject: Re: Tether up, then release to untethered phase. Then drive on board

Group: DSUTWP	Message: 53	From: Gabor Dobos	Date: 2/23/2014
Subject: Re: Tether up, then release to untethered phase. Then drive on board

Group: DSUTWP	Message: 54	From: dave santos	Date: 2/26/2014
Subject: Re: Tether up, then release to untethered phase. Then drive on board