Kinetic tension energy storage ?

[MaxT]

I was trying to ponder whether the bow structures could be utilized in low-tech conditions to store and release kinetic energy in rotation.

So, no metallic parts, no bearings, just wood and rope.

I do not know, but this is what I have thus far come up with. It's not ready display of anything tested or "known to work"... it's just ideas thus far.

Do notice that: storage is for short time. Windturbine or waterwheel energy could thus be stored during the night, for some minor uses during the day. When bow limbs finally wear from use... they can still be used as firewood as originally.

Someone claimed to me that traditionally crafted asian bamboo bow can store up to about 100 times it's own weight in "pull power"... whatever that precisely means in layman terms. That sounds great... it could make these sort of somewhat movable batteries... like from waterwheel to whetstone... or whatever needs rotating.

Pictures depict a big ball in the lower samples. Forget those ball things. I think that synchronizing axle in the central is useless and unneccessary also... and rope transmission should be at the "waist" of the contraption, while it's top and bottom ends are securely attached to immobile frame.

Pictures show 6 bows attached to 2 wooden rings inside them. Wooden rings could be reinforced, bows could be much more numerous and much thicker than those used for hunting and hobbying.

Bows are built to curve to the opposite direction, than the hand-held bows of hunters.

I also understand that building a powerful and functioning, light, traditional asian bamboo bow, can take months or years, as the wood is cured, and so forth.

Only claims I further make about this is that, for now, accordingly my know, it is untested and possibly unsafe and risky. It could dangerously whack / hit someone too close if any of the bowlimbs becomes loose, for any reason (string breaks, when tied up for storage, the tying knot opens, etc...). And less there is grip in the transmission with ropes and the transmission "junctions" (what are these called ? Did they not have some on sailing rigs, like this ?), the more there is friction and faster the whole thing turns into a fancy way to make a bonfire: burns up.

[DanB]

Interesting drawing!

It doesn't seem very practical.  Consider...

1 hp = 746 Watts = the ability to raise 33,000 pounds one foot in one minute.

So if you 'charged up' a 33,000 pound bow (that would be one heck of a bow!) and the string moves 1' over 1 minute, you could have 746 Watts over that period of time - or... about .01 KWH.  Considering the complexity of the system - and the size/scope of a 33,000 pound bow (or I suppose you could use 330 smaller 100 pound bows) - I would probably look for a deep cycle battery!  Even a small marine /trolling motor deep cycle battery (about $100) can store about 1KWH (100 times the energy).  

This reminds me of the common email I get from people who think perhaps it's a good idea to store energy by raising weights.  Unfortunately you would have to raise a lot of weight a significant distance to store very much usable energy.  There is no comparison between this sort of thing and a battery.  If life is so primitive that a battery cannot be had, then I expect saving energy in the form of animal feed or engine fuel or something makes a great deal more sense.

So yes - you could store energy this way but not much and it would be a very poor use of resources I think.

[coldspot]

MaxT-

Interesting,,..

My $0.02

"I also understand that building a powerful and functioning, light, traditional asian bamboo bow, can take months or years, as the wood is cured, and so forth"

The time it takes to tiller a bow from a stave to finished bow can be very short, but the seasoning of the wood for proper moisture content, can be as you stated months to years or hours, getting the right "MC" for your own Relative Humidity is the part that gets some people.

 I'm a newby bowyer but have built each of my four kids a selfbow using "Rattan". It's like Bamboo but not hollow.

The 3rd and 4th bows turned out in the "Legal" hunting weight draw of over 40 Lbs @ 28",,.. !!!! Also @ just over 4' long,,..!!

[MaxT]

Yes what you say about the energy efficiency is very right, and became quite apparent to me early on thinking about this... but thanks for the more precise maths.

What I thought of it's usability is not really for the areas and communities with access to technological infrastructure... or it's products. I'm thinking of very poor and/or distant communities with very little resources. No magnets, no generators, possibly no metals either. Whether this set up could be used to save (starting from) 5000kg to 10 000 kg of energy during the night to power some tools and equipment in the next day... with each 100kg (200+ pounds) of bows used for such purpose.

Milk separator for some of the asian distant villages has been proposed as one potential idea... I do not know whether this would actually be useful for it... Performing just some small low-tech tool tasks in communties which otherwise have to use their precious musclepower for it. Such villages may well have apt carpenters and bowmakers though... so that's kind of the point, for now, for this oddity.

Also to be inspiration for various peoples, into designing new stuff and tools... even if idea turns out a turkey, some parts of it may turn out useful in other designs... which may eventually do much good.

[MaxT]

On second thought... I do not follow those maths. At all.

Should it not be that I need 200 pounds of bows to get 10 000 to 20 000 pounds of energy ? Though what that is in watts and joules I don't know. That is just the "pull" strenghts of the bow material, how much energy is needed to load it, and thus, about how much is released when it is let to unload. But Watt means Joule Means 1m per second trajectory for 1kg of matter (to any direction ? In zero G ? In surface atmosphere ?)

[Stonebrain]

You have to understand that force is not the same as energy.

So 10000 or 20000 'pounds' of energy surely doesn't make any sens.

energy is force multiplied by distance.

So if your bow has a force of 33000 pound over one foot you have

33000 'pound*foot'

How much joules is one 'pound*foot'? Well,I don't know,maybe you can find it out yourself,good exercice.

hint:1joule = 1newton*1meter

I recognise DanB complicated the maths by calculating power (energy per time = pound*foot/minute) first,what is kind of longer way to come at the result.

cheers,

jaap

[MaxT]

mmmyeah, actually it was not the maths that confused me... the units.

I thought he was talking of 33000 pounds of bow material weight, not the stored energy amount. And might be my math question makes no sense in pounds etc... as I never understood much of the Imperial units.

I guess the issue calculating the feasibility is what precisely does it mean in the bow "pull" power as they are measured (in pounds, grams, kg's). How does that translate into watts and kilowatts ?

I mean that if a strong bamboo bow is reported to weight about 500g and to have a "pull" of 25kg to 50kg (traditional ones... I'm not sure if many people nowdays posses the trained and cultivated archer anatomy to use the stronger ones), does it mean that it takes a heavy weight of 25kg hanging from the bow string to load it... or does it take the energy of 25 joules / watts to load it ?

That Joule definition I came by: accleration of 1m per second for object of 1kg to given trajectory... I was wondering what does that mean ? In what conditions ?

Actually I was told that 1/2 kg bamboo bow could have a pull of 50kg whuch could mean that it can store a 100x it's weight in KG (Newtons ? Joules ?)... or 100x of it's weight in this "pull" which is still a bit of a mystery for me to convert Joules. Actually I think that must have been a mistake, confusion between kg and pound units, and the actual real "pull" has been about 50 pounds for 500g of bamboo bow. Since I'm not an archer I don't know, but I assume the smaller capacity.

Thus I can count that 100kg of such bow material has a "pull" of 5000kg's (about 10 000 pounds) but have not a slightest clue how to convert that to actual Joules and thus Watts. But without Dan's reply I'd still have no clue of horsepower and KW comparision, and it cleared my understanding of the related maths a bit.

(I really don't know, either way about the contraption itself, and thus it's here to lure your knowledge and experience into itself)

[MaxT]

You seem to know about bows... so I'd like to ask a question:

Bow has a "pull" or "draw" capacity. How is that measured ? How can I convert that to the actual Joules / Newtons / Watts that are thus stored into it, and thus calculate the storage potential ?

I heard of a traditional asian bamboo bow with weight of 500g and "draw" of 50kg... but find it hard to believe, so perhaps it was actually a "draw" of 50 pounds ? Which one sounds more realistic to you ?

Like they sure had some amazingly strong bows, but who anymore can use such ?

MaxT

[Stonebrain]

Hey Maxto,

You still ask lots of questions,but you didn't do your exercice.

ok I'll do it for you,

1) do a google 'joule'

   go to wikipedia: 1kwh = 3 600 000 joule (= wattseconde)

2) Someone told: 0.5kg bamboo = 50 kg pull,

   wikipedia:1kg=10 Newton,so 1kg bamboo has pull of 1000N

3. guess:bamboo can pull over a distance of 1meter (hey!,this comes out nice!)
   
4. stonebrain said: 1 joule = 1 m.N
   
5. Final assembly: for 1kwh = 3 600 000J of bambooflex, you need
   
   

                   3 600 000 J = energy content of 1 kwh

                   divided by

                   1000(pull in Newton)*1(distance in meter)

                     =energy content of one kg bamboo  

3 600 000 divided by 1000 is 3600

To store 1 kwh in bambooflex you need 3 600 kg of bamboo.

Looks like a fun project.

cheers,

stonebrain

   

[Stonebrain]

Hey Maxto,

You still ask lots of questions,but you didn't do your exercice.

ok I'll do it for you,

1) do a google 'joule'

   go to wikipedia: 1kwh = 3 600 000 joule (= wattseconde)

2) Someone told: 0.5kg bamboo = 50 kg pull,

   wikipedia:1kg=10 Newton,so 1kg bamboo has pull of 1000N

3) guess:bamboo can pull over a distance of 1meter (hey!,this comes out nice!)

4) stonebrain said: 1 joule = 1 m.N

5) Final assembly: for 1kwh = 3 600 000J of bambooflex, you need

                   3 600 000 J = energy content of 1 kwh

                   divided by

                   1000(pull in Newton)*1(distance in meter)

                     =energy content of one kg bamboo  

3 600 000 divided by 1000 is 3600

To store 1 kwh in bambooflex you need 3 600 kg of bamboo.

Looks like a fun project.

cheers,

stonebrain

   

[Stonebrain]

Sorry,

in 'plain text' it just comes out better then in 'autoformat'

[MaxT]

mmyeah... tried to do that a bit... good definition that Joule = wattsecond, I would not have realized that one, thanx for that.

Apparently the draw lenght is even much less than one meter. I went to search the traditional archers' pages about the joule count in those bows... and those maths they used just confuse me for now (don't worry, I'll do my homework, just have not yet have had the time). They seem to Indicate truly odd things about bows and Joules... like "draw lenght" is about one foot, Draw weight is something like 30kg to 40kg (this was for strong British-type longbows... much heavier than bamboo bows of same Draw) and then the Joule amount comes out as something like 107J stored in such ancient type of bow. Various calculation forms for counting the energy amount I have come by... and they seem to happily mesh Imperial and Metric units without being quite clear (yet) to me which type of unit system is used and where.

Tables and calculations for modern compound bows were much easier to come by and comprehend... byt they are useless in this project without the compound bow materials and structures.

Homework continues.

[feral air]

Springs, which bows are a type of, are rarely used to store large amounts of energy for a reason. In order to store useful amounts of power the spring would need to be monstrous and then it couldn't be moved easily and it'd have lethal potential.

Building a contraption like this would be a colossal waste of resources. It'd need to be scaled up to the size of a small apartment building. At that size, with the labor and materials costs, you may as well build a few hundred merry-go-rounds and strap your chickens to 'em.

Chicken power is thus copyrighted 2007 by me and is free to all who were ever or may ever be in existence.

It may not be a storage solution but if you could motivate your chickens sufficiently you'd have power on-demand. A total solution to the worlds food and energy needs is thus born.

[TomW]

feral;

Tell us what you really think.

T

[MaxT]

Hmmm... thank you for the speculations about the chickens and the utilization of their exercise potential. slightly off topic though that may have been... (and perhaps even will be, forever and ever and ever... which is an accomplishement in itself).

The rustic copyright clause typed therein may seem like first step on an aspiring career as a megalomanic, but it has a deeper rationale. In all sorts of designs, in all applications of those designs, it is useful in stopping some hoarder type-, generally harmfull-, of copyright claims as personal property of one corporation or another company.

Without any copyright protection, the first gadget hunter might even score the above for some toy company, thus preventing rural craftsmen legally from making funky geegaws of it to tourists' kids, for example. Since I do not believe in hogging (many) copyrights, or sittin on top of a some potentially useful invention for decade of product developement and loans and funders... in hopes of some possible royalties someday... and a right to fight in courts for the magnificent undying glory of being forever remembered as the mighty wise person who invented a petty geegaw... I rather avoid that by copyrighting most of the stuff I put in Net, at all, as freeware, public domain, and so forth. Most of the stuff I do are some silly cartoons and the like... It is so awkwardly specific, because in the glorious land of milk and honey, the free and the brave have decided it justice to declare people criminals for using mere freeware software products, and punish them for that. The argument in the specific legal case was that the product has to be specifically lisenced to each individual user, or each individual user without such lisencing may (and will, it seems) be prosecuted and sentenced to fines and or punishments.

So by just adding that somewhat silly looking freewaring copyright disclaimer, amazing amount of useless fuss is avoidable. Some things and deeds are practical, though appearing rather silly.

And as we can see, due to the potential usefulness, or uselessness, of this particular idea and it's applications, this thing was not posted in any areas with need for seriously tested, guaranteed to work, stuff, but here for those commentators with kindness to lend their time for examining other folks diaries of oddities.

[feral air]

Quickly, from wikipedia...

"Copyright law covers only the form or manner in which ideas or information have been manifested, the "form of material expression". It is not designed or intended to cover the actual idea, concepts, facts, styles, or techniques which may be embodied in or represented by the copyright work."

"Obtaining and enforcing copyright

Typically, a work must meet minimal standards of originality in order to qualify for copyright, and the copyright expires after a set period of time (some jurisdictions may allow this to be extended). Different countries impose different tests, although generally the requirements are low; in the United Kingdom there has to be some 'skill, originality and work' which has gone into it.

[ ... ]

In the United States, copyright has been made automatic (in the style of the Berne Convention) since March 1, 1989, which has had the effect of making it appear to be more like a property right. Thus, as with some forms of personal property, a copyright need not be granted or obtained through official registration with any government office. Once an idea has been reduced to tangible form, for example by securing it in a fixed medium (such as a drawing, sheet music, photograph, a videotape or a letter), the copyright holder is entitled to enforce his or her exclusive rights. However, while a copyright need not be officially registered for the copyright owner to begin exercising his exclusive rights, registration of works (where the laws of that jurisdiction provide for registration) does have benefits; it serves as prima facie evidence of a valid copyright and enables the copyright holder to seek statutory damages and attorney's fees (whereas in the USA, for instance, registering after an infringement only enables one to receive actual damages and lost profits)."

Rural craftsmen don't give two dingle-berries about intellectual property law. If I want to make a geegaw for personal use, I will, patents and copyright be damned. If I was barely surviving, double that sentiment.

[TomW]

feral;

Near as I can tell an individual can pretty much ignore copyright for personal use.

Besides if you don't defend it its about as useful as breasts on a pickup.

That whole statement imprints "flake" in my mind in association with the user but thats my problem I guess.

The fact that it has been published and dated makes it "prior art" which makes the statement redundant at best to me.

I ain't no damned lawyer, either.

If we killed them all we might make things better in general.

/rant.

Cheers.

TomW

[ghurd]

"about as useful as breasts on a pickup"?

My grandpa said "Useless as teats on a boar hog."  Teats weren't a bad word then, and it still ain't around here.  Teats is just teats.

It is relevant, because boar hogs have teats.  Fords & Chevys do not.

And a patent is only relative to the guy who has enough money to defend one.

BEFORE he had one.

G-

[feral air]

Tom, you're spot-on as usual. I guess I have the same problem and I've been letting it get the better of me.

I think my point was that explicitly copyrighting the post/art won't stop someone from hoarding the invention or idea because copyrighting is not the same as patenting.

If you came up with something new and amazing and shared it this way someone could probably come along and patent the idea anyway. They'd have to change the wording and art when sending it into the patent office so that they aren't violating your copyrights but they'd want to do that anyway.

You could attempt to take their patent by claiming prior art (if that's how it works) but you better have deep pockets. Even if you win, all you get is a patent, for a lot more than it would've cost to get one in the first place.

That's just how I see it but like Tom, I'm not a lawyer either. I never even played one on tv.

[feral air]

Sorry, I'm pretty sure it didn't preview that way...I wasn't trying to yell...

"You could attempt to take their patent by claiming prior art (*if that's how it works) but you better have deep pockets. Even if you win, all you get is a patent*, for a lot more than it would've cost to get one in the first place."

[TomW]

feral;



Sorry, I'm pretty sure it didn't preview that way...I wasn't trying to yell...



Yeah and "patent" turned into "copyright" on my post. I blame it on the meds they get more powerful all the time..

Schtuff happens.

Cheers.

TomW

[MaxT]

"That whole statement imprints "flake" in my mind in association with the user but thats my problem I guess."

My problem it is... and a somewhat correct definition even. Even folks and factions who dig and use some of my stuffs cling to that. And I can't dispute it, and I don't think I should: Sometimes some of my stuff turns good and useful for various folks and purposes... at other times some other stuff turns out just obscure and odd... and much of the time I can't really tell the difference myself.

Thing I work on for months, even years, may turn out really flunked oddity... and something I brought along as "silly ideas for for fun oddities" can turn out to be high interest stuff.... I guess I have a problem with a degree of practicality estimations.

(I'm still trying to get the proper maths for calculating the meek storage potential of this thing, before having a idea as to whether it can be used as "first aid" for wrecked communities with no access to anything industrially produced... at least for a time being. Strongest argument is, whether it is worth the effort, or better used directly as firewood... generators, wires, metal parts, powertools... they generally require massive industrial infrastructure as a source, and there are people who can not benefit from such access. the "draw" of the bow is not the same thing as how many 1kg weights they can launch at 1m per second trajectories. Not by a long shot, it seems. So maths can not be based on that, no matter how many times I get that formula repeated... so, still trying to research that).

Learned to be vehemently stubbornly paranoid with copyrights, working in the illustration and comix industries. Also, in one such cartoony piece an invention about a principle was first presented... as a joke. Later on a company took the idea seriously, patented it, and started to prepare gadgets working on the principle (not sure they got that far...). The company lost big way. Patent went (in USA) to the party that had first publicized the idea and concept in the copyrighted work... copyrighted like the illustration above.

In poor (often pillaged) countries it matters not much whether poor craftsman has the bravery to prepare the patented-type geegaws to be sold for tourists, for family sustenance... as corporateer paid security/police-force will break those people into smithereens for such infriction, brave or not.

I'd rather see these things launching traditional "bamboo dragonflies" on family stalls in asia... than as toxically produced "animated series -promoted" plastic toy corporation "monopoly". That's completely fictional scene of course, just as an example.

Better safe than sorry.

[feral air]

The second you hit the "Post" button, your post is copyrighted and is conveniently time stamped. You don't need to say it's copyrighted because it already is.

"Copyright law covers only the form or manner in which ideas or information have been manifested, the "form of material expression". It is not designed or intended to cover the actual idea, concepts, facts, styles, or techniques which may be embodied in or represented by the copyright work." -- wikipedia, emphasis mine.

"the "draw" of the bow is not the same thing as how many 1kg weights they can launch at 1m per second trajectories. Not by a long shot, it seems. So maths can not be based on that, no matter how many times I get that formula repeated... so, still trying to research that)."

The best way to figure this out is to do some testing. Go buy a pair of those "moon shoes" or something...they're usually bow-based. With moon shoes you should be able to figure out how many watts go in vs. how many come out...how much force are you applying vs. how high do you go?

[feral air]

Air Kicks were the first pair of "moon shoes" I could find. They use "rubber T-Springs" whatever that means...so not a perfect comparison to a bow but they could give you an estimate of the potential and maybe ideas for improvements.

[MaxT]

For clarity, that copyrighted publication of a concept, that was not me, and had nothing to do with me. Just and oddity in a animated series.

[MaxT]

If all else fails, I'll have to just devise a test with one of those traditional asian bamboo bows, arrow of a known weight, and it's speed when released. Then compare that with the "draw" of the bow, and then with the weight of a bow... and I'll have rough estimate. If it looks like having any practical potential in some remotely possible conditions, then comes calculating the work amount that goes into the bow... and sociological effects from bowmaking, and so forth.

[MaxT]

I don't know why precisely, but reply like this makes me seriously (I mean it) wonder why I bother trying at all. That's assuming it was not a serious suggestion.

Just in case that it was a honest suggestion, then let it be mentioned that moonshoes won't do no good at all at this research.

Amazing to automatically assume that I would even have the funds for such.

I guess it's easy to build any sort of wind turbines and other experiments in independency if you happen to be affluent enough to have obtained the industrially made powertools and factory made components from hardware stores.

If I'd have such, or similar, resources at my disposal, perhaps I'd be building and testing these things instead of just posting them here... and having to find out that I have only inspired discussion about "chicken excercise power", "Silliness of freeware copyright clause wording" and "hilarious" recommendations to buy moonshoes. (Totally abstract question, any apparent relation to subject above is probably just coincidental: just What would actually be hilarious in getting someone to buy more of some toxically slave labor made pieces of rubbish ?).

[TomW]

Max;

Gee, I don't know how to respond here in a way that won't be misunderstood or thought to be negative.

Personal opinion and calling a spade a spade follows:

You pop in here and post some wild Rube Goldberg looking devices that obviously [to many of us] will not work or make no sense. Add your little disclaimer that I, for one, find ludicrous when attached to such a drawing. Then get put off when folks respond in ways you do not feel is fair or something.

Welcome to the Internet.

If the apocalypse arrives I seriously doubt anyone will be reverting that far back. There will be useless cars, trucks, buses and trains everywhere with steel springs and lots of other modern materials that will be adapted to new uses.

The stuff you posted here is what I think of as "desert Island" methods. You are stuck and need to pump water or hoist stuff or whatnot and electricity will not be needed or useful.

An email address beginning with "reconstructionimminent" leads me to believe you are looking forward to the collapse of things as we know them.

I guess I just do not "get" where you are coming from on some basic level.

Why discard thousands of years of technological advances to build an inferior device that may or may not work, especially at a point in time when you have no time to experiment or fail?

Hope that makes sense.

Cheers.

TomW

[MaxT]

Points:

The device does seem to work. It's practicality is what I am asking.

That copyright is in most of my drawings, cartoons comix, whatnot. Copyright is ludicruous and in saner times we needn't bother. Thus far it has saved my stuffs (comix and cartoons) from many a ripoff.

About "apocalyptic" reverting back. World looks mighty technological from here in richer areas. No use in telling people in Nigeria or in Moroccan desert refugee camp, and many, many, locations like that around the globe, that steel car springs are always available. They are not. It's "only" very large part of the world and humanity that already has been pillaged back to stone age, and to toxic and depleted conditions. Many such locales need just working blueprints in how to start caring for their land, and themselves, not destructive "aid" that drives them into eternal debt servitude and crushes whatever local industries were left.

For practical examples:

http://koti.mbnet.fi/maxt/selkistuff/

http://www.selkikeskus.com/English/indeen.html

http://koti.mbnet.fi/maxt/nergfarm/nergfarm.html

Such "sheltered" and pleasantly filtered picture of our world we are being pushed. Do we have to swallow it ?

email address just refers to many of our things being already malfunctioning, on a course "right off the cliff" (like Caspian sea went), and them needing restructuring and organizing before we fumble more. I'm no fan of apocalyptic "manly" survivalist visions.

Imagine a device that is made with fossil fuels, heavy mining, global transporting, sweatshops (and worse) around the globe, massive material processing and production structures... even if that thing would be a wind turbine generator, or it's component, would it ever truly pay it's true energy, ecological and cultural costs back ? Local production is a separate thing, but even then energy and work has to be accounted for when counting the feasibility.

The depicted device stores a fragment of energy when compared to pretty much any form of combustion engine, or electrical battery, in it's weight. Yet, it can be grown locally from wood or bamboo, organically, and burned to ashes (suitable to plant nutrients, as well as producing a degree of energy in heat) after it's life cycle in use. Instead of hundreds or thousands of workers around the world being involved in energy intensive and ecologically unsustainable production behemoths, a single person can do it from plantig and growing the bamboo, the rope fiber plants, and doing all the work stages.

Yet, I am not sure of the feasibility and practicality. I hear that some research (well, "homework" for me) on condensators might come up with something much more effective, even if still very simple and entirely "community makeable" (though with some more work).

J.R.R. Tolkien called the modern technologies just "Hiding the work out of sight". How right he was. At it's simplest, coal miners labor and toil was hidden when transforming that coal into electricity: seemingly nice and polite to just switch on the electrical toaster, and to think that the toasting power was free and clean and just came out from the electric outlet. And now we have to fix and reconstruct the things that the "free" energy in the coal released as poison and pollution to all world around us. And all the rest of the "free effectivity" from the fossil fuels and mining products, as that "free" part turns out to be environmentalized poisons.

Perhaps I was naive and stupid in expecting the discussion like this:

http://koti.mbnet.fi/maxt/Communication/communic.txt

here in the Internet. In that you are right, I should have known better from the experience.

Like you, many posters were polite and patient with me, some even encouraging.

To me it seems there is no sudden simultaneous global collapse coming. Many huge areas have already collapsed and the collapse creeps on. Disgustingly inept of us wealthier areas, is how many poor areas with devastated ecologies, wiped out cultures and erased traces of civilizations, were not so poor and unviable a generation, or three, ago.

You wanted to know where "I'm coming from". I tried to explain it here.

[feral air]

"Amazing to automatically assume that I would even have the funds for such."

I had a rant all ready to go in this space but I think I'll keep it simple instead. I work hard for mine too. I'm not the rich white boy you think I am, I'm a poor-yet-proud american redneck.

Besides, you missed something in this sentence; "Go buy a pair of those moon shoes or something"

That "or something" was a conscious addition. I didn't assume you could afford a pair or that you would even want to. If bamboo is readily available then go experiment with some, or something. Even if it's not a masterfully created bow all seasoned and whatever...it'll give you an idea. Maybe multiple ideas.

At this point all you've got is a half-baked idea, just like the last one I criticized. There's no real way to put numbers to it, there's just too many variables. Stonebrain's numbers look like a best-case scenario to me (what of transmission losses, poor build quality, etc?) but not too wild...3600kg of bamboo to store 1kwh.

Different bows will have different properties, especially if they're hand crafted from natural materials. Does that affect the device and what's that do to the output? How do you keep the bows from being overdrawn? What other problems am I going to run into if I try to build this? There's too many unanswered questions.

Build at least part of something. Then test it and even if it's best-guess measuring you'll have something.

[MaxT]

Bows can't be overdrawn in this. there's a limit to their motion. Once they reach the central hub, that's the end of their bending trajectory. I don't see the transmission eating much of the energy if it's done propely, seeing that there are no ballbearings nor any bearings to cause that. The issue is avoiding "all" the friction in the rope-suspended transmission hubs (I still don't know what they are called in english) and maximizing the grip of the ropes. Equally spaced knots comes into mind as a first manner of solution, but something better will have to be eventually thought and crafted... if it still seems worth the effort.

Bamboo is not available at my northern and urban location, but I think I can scavenge some abandoned blonde, hard, plastic tubing they store the smaller electric wirings in constructions, and discard when renowating / tearing down old structures. That still leaves the question about what to use as the two structural loops. Yew tree and pine are available... but I would not waste living trees, especially bow quality ones, one me trying out experimental things with by bungling skill levels... I rather leave them to actual bowmakers. Hmm... cured willow is readily awailable, which I had previously discarded as too thin... but cured willow should be quite good for miniature versions.

The upper and lower string hubs will be relatively easy to improvise, as will the tying up "mechanism" for storing the loaded thing... but for the first model the transmission will be left out entirely (gutted bicycle wheels ? non gutted inside as structural loops, gutted outside as transmission tracks ?... still, these are harder to scavenge), as using the rope suspended transmission will require at least 2 of these contraptions to suspend it... and as is apparent, I do not yet know whether that will be worth the trouble.

Mostly offtopic Addition of exotic local color follows:

(Due to unexpected public transport 80€ ticket fee from being 200m out of my stamped ticket area zone, these preliminary experiments may have to be postponed for another month. Damn... turned out to be most expensive 500grams of edible wild mushrooms I have ever picked... Word on the street is that the adminstrators of these city areas don't get along and are having a hissy fight for a 10th year, and we citizens of both areas end up paying in all sorts of imaginative ways as they seek to get "one up" on each other by pestering each other's areas' inhabitants).

[feral air]

"I don't see the transmission eating much of the energy if it's done propely, seeing that there are no ballbearings nor any bearings to cause that."

Bearings reduce the energy losses by reducing friction and its byproduct, heat.

"The issue is avoiding "all" the friction in the rope-suspended transmission hubs (I still don't know what they are called in english) and maximizing the grip of the ropes."

Collectively, it's called tackle. Most people I know would call what you drew a block and tackle to distinguish it from fishing tackle and football tackles. From my dictionary; "tackle (2) a mechanism consisting of ropes, pulley blocks, hooks, or other things for lifting heavy objects."

The best way to reduce the friction in the block and tackle is to buy a commercial set from a hardware (hunting, maybe) store - they'll have semi-decent bearings usually. Otherwise you make the holes in the pulleys larger than the axle rods and use lots of lard/lubricant so that your wooden pulleys don't catch on fire.

[MaxT]

Tackle. Good to know.

But no there will be no bearings, of any kind. That's the very point of these... "tackles". They are just solid blocks suspended in the air by the tension from the pull on the ropes. The contraption's transmission rope loops are very near the center of the "tackle's" axle... and the rope loops that go to operated application to be rotated (or to next "tackle"... still sounds odd to me...) are far away from the central axis of the tackle's rotation, thus travelling much longer journey at each cycle. In this way tens of rotations of the contraption can be transformed into hundreds, ore more, to be of any use. No bearings. Solid block. Low tech. No industrial parts needed.... and since this Tackle thing you describe seems to have bearigs... I'm not sure if this thing is officially a "tackle" (I still am not native english speaker). Since there are no stationary axles which would require bearings... There seems to be even less friction on the motion than with (significantly) reduced friction with the bearings.

I'd say it's odd and unorthodox, but should work fine... except I think it's not odd or unorthodox, since some (at least) modern composite bows seem to use such tension suspended bearingless tackles. Don't ask me why precisely they have them, my understanding thus far, stretches to triggerbows and dual-opposing-bow suspended-lever-string trapping crossbows (Which may be ancient, but I consider their mechanism brilliant... especially since they seem to be more hunting than warring oriented).

Oops. I just checked the Web. All Tackles depictions have fixed axle around which they rotate. Therefore the depicted transmission things in my picture are not, at least the common type of, tackles. Ah the world of misunderstandings... the same thing happened to me with gravity pumps. All the time I had been referring to gravity funnels, but that's another story.