It is Wednesday my dudes, 15:56, 22/02/2023

Well, let's see if I can get this right this time.

I will first try to make that dang equation work, and then I will try to see articles using actual heavy duty McKibben muscles and guess the dimensions mine should be.

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Well, the value of pressure is in Pa, not KPa, it seems :|

So this means that the McKibben force calculator I asked ChatGPT to make is incorrect, right?

Just tested and it seems so, dunno what it is wrong :/

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As you may think, yes, I don't actually need 34000 liters per minute ALL the time...

... But I don't know how many muscles and how fast these muscles will need to be actuated during usage.

I can't just base myself on the human body, because we use around 200 muscles of our 600 to walk.
My mech just has 72 muscles. :|

Taking that 200 is just a third of 600, maybe I could make the assumption that I would just need to actuate 24 of them.

So, 39 liters per second, which gives 2340 liters per minute, or 7020 liters per minute if I need to actuate in a third of a second.

This means I would need more or less 3 to 8 of that pump I designed for this mech, the one that can supposedly pump 900 liters per minute.

Well, it would need to use 3 to 8 times more energy, since it simply uses 750W to supposedly achieve that. Which would give 2250-6000 watts per hour.

A literal two 3000 watts battery (that costs 1 thousand bucks in my country) per hour, and my mech would (initialy) carry around 6 of those.

Meaning this would just have 6 to 2 hours of operation time even if I used it in 1/3 of rated power. :/

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Also, I keep asking around the internet (specially on stackexchange) about ways I could improve thigns here, and EVERY TIME people say:

Random person: "I just found an *insert object* that does this exactly thing you're in need, you're just not researching enough."

Me: "I couldn't find this *insert object* you're talking about, could you send me the link?"

*never answers again*

I f*cking hate the internet.

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I also received another answer saying that this is called "impedance matching problem", and that I should read this book called "System Dynamics: A Unified Approach", it is a 500 page long book.

I'm supposed to just read about this section in specific...

... And I searched for "impedance" and only two results about radios appeared... :|

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Well, this means that I will need to increase its pressure exponentially in order to decrease the fluid flow required for the mech...

And searching for articles on high power McKibben muscles I only come accross McKibben muscles made out of Vectran and other super ultra expensive fibers.

Even though I intend to make these out of super thick steel cables, I still feel like these won't be able to handle the forces involved. :/

As a brazilian saying says: "I will have to give my jumps" (aka pull myself by my bootstraps/make my ends met).

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One way I think that this could be possible is make multifilament McKibben muscles out of super resiliant materials (such as steel or aramid).

If you don't remember which these are, these are basically a single long hose/tube covered by a single long sleeve that can be rolled up and work like a single muscle.

As you can see, you need half of the pressure/fluid used in a single McKibben muscle.

The problem is that you need kilometers and kilometers of material in order to lift a single ton.

Basically, on Project Log 7 I calculated I would need 4,4 Km of tubing to lift 1 ton.

Well, I don't actually need a rubber/silicon inner tube, I can actually just use LDPE (low density polyethylene) plastic bags melted as a single tube.
The filaments for the braided sleeve could be single filament steel wire.

Both are incredibly cheap, even in the kilometers. (also, I don't actually need to use LDPE, I could use HDPE or UHMWPE plastic bags).

Now the question is: How to make a machine that mass produce these? :/

There are DIY 3D printable braiding machines, but I couldn't find any available for free.

Maybe I'm just being lazy, but I will try to figure out how to make one.

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Oh yeah, I forgor that I had to calculate the fricking fluid flow of this thing.

Well, a single filament with 30cm in length and 0.9mm inner diameter, a single one of those has 0.001 liters, and since 10 of those lift 1 kg, I would need 50,000 thousand of those 30cm muscles (15 km in total) to lift 5 tons.

I would have 9 liters per bundle of muscles, and accordingly to that pipe volume calculator, if the length shortened in 20% and the diameter increased in 40%... I would have... 1496 liters inside of a single muscle bundle... :|

Okay, that's not it.

(for hydraulics)

And yes, I could braid then even more for even more strength, but really? Realistically braiding 15 kilometers of this crap? No way.

But I will try to figure out how much air flow one would need to pressurise 15km of filament, which I doubt will be simple.

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The hydraulic McKibben articles that I encounter achieve maximum 8 mpa of pressure (80 bar), while hydraulic cylinders achieve around 12000 PSI (80 Mpa/820 bar) using the best of the best materials...

Well...

It seems that I will have to check how much fluid flow hydraulic cylinders under these circumstances will need, and then check how much energy I would need.

Since the muscles would work around 6cm of actuation, maybe I won't need that much power.

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Well, Aliexpress is kinda weird, because some times it shows a really cheap product in which its shipment fee costs 21983209239 times the product value.
Normally the 5 ton rated hydraulic cylinders cost around 100 brazilian bucks, but the shipment fee is literally 900 bucks.

This is a chonky boy.

Well, I tried this hydraulic cylinder calculator, inserting the values given by the seller on this hydraulic cylinder and the calculator said I would need 1.5 bar of pressure inside of it in order to apply 5 tons of force and a oil flow of 1800 liters per minute to activate it in 1 second. :|

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Edit¹:

I just tried the calculator again and it is saying I would need around 157 bars :|

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And normally hydraulic pumps can output 30-54 liters per minute under 1750 rpm with 14 hp for 150 bars.

I recalculated stuff, and for some reason I don't know where did I came up with 400 liters per minute, but basically, I would just need 67 liters to pump all the 5 ton hydraulic cylinders.

Again, I misscalculated again.

It is 67 liters in a third of a second under 7.5 horse power (assuming I'm not using the full 5 ton capacity).

This means I would need 4043,52 liters per minute.

This means I would neeed 74 hydraulic pumps under 7 hp each...

This means I would need a 518 hp in total, or a 100hp engine for each limb.

For perspective, here is a video with 400 hp cars:

If I just went with 67 liters per second, I would need 1320 liters per minute, which means I would need 24 pumps.

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In the pipe volume calculator it said I would have 0.312 liters inside of this cylinder alone and only 18 liters per minute.

This means that I would need 22 liters to activate all the 72 cylinders and 4043,52 liters per minute to activate all of them in a third of a second...

Which is better than the McKibben muscles... Humm

The problem is that these cylinders are expensive as f*ck and heavy as f*ck aswell...

Each one of those weights 9-10 kg (720kg in total), and on top of that, I can't find any accessible here on Brazil (my country)...

I would be forced to adapt hydraulic jacks to hydraulic cylinders, but I feel it takes too much work and it would be too poorly made (by me).

I can always search for scrap metal, but after looking at some scrap yards around my town, I couldn't find nearly as much useful stuff as I needed... :/

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If the diameter was 4-5 cm, I would need something around 200 bar (20 MPa) of pressure and just 7 liters per minute of oil flow.

If I can find this "mini" hydraulic cylinder for 5 tons is another matter though...

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There actually mini hydraulic cylinders that does that...

But as you can see... Their maximum travel is around milimeters.

And I did found one with a bigger travel...

But these cost around 2000 reais (390 dollars).

By the way, the increase in pressure means increasement on the torque necessary to pump the fluid, and horsepower = torquexrpm/5252.

So, taking into consideration that some hydraulic pumps already come with the horsepower required to achieve certain pressure, I would need around 20-30 hp to pump around 40 liters per minute with 200 bar of pressure.

Besides the cylinder calculator saying I would need whatever value, this cylinder has space for 0.100 liters of hydraulic oil.
So, 7.2 liters in total, even this value per second, I would need 420 liters per minute.

Which would force me to use 200 hp to make this work. :|

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And yes, I'm really reconsidering this stupid idea of pump ALL muscles at third of a second, I don't need this massive amount of flow.

But I don't know what should be the ideal amount of flow... :/

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I guess the maximum would be half of the muscles, since I would more or less just actuate the equivalent to half o these.

So, 36 of those would need around 96.48 liters, which would need a maximum of 289.44 liters per second, which would give 17340 liters per minute...

Exactly the half of 34 thousand and something that I said before. :|

Well... I guess I would just need 20hp gas engine pump to work with it...

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So 34 thousand liters per minute it is. 

I literally have no choice.

🥹

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Edit:²
I forgor to say that I could just take those 10hp motors used for generators or small machines and put a hydraulic pump for each, which would aliviate the stress on the engines/pumps.

Now I have to calculate how much fluid flow each engine will generate through each pump and each hose. :|

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Well, I could use pneumatics and I could use hydro-pneumatic (where the pneumatic pump is the one responsible for pushing the air), but like I showed before, I would still need liters and liters of these things, not to mention the efficiency loss from converting pneumatic to hydraulic.

I'm always open to suggestions btw.

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Edit³:

Actually I had written something in here, but I took so long researching for stuff that the page refreshed itself.

But basically, I will need to remake the entire pump calculation because the previous one that I "designed" simply wasn't well planned out and didn't take into consideration the torque necessary to rotate stuff.

I was searching for actual combustion engine pistons, its components and so on, basically, there actually are a lot of them for really cheap on the internet.

The problem is that besides being cheap, all of them have completly different sizes, with different pieces and different functions.

This means that it isn't as easy to measure and estimate things because the sellers don't always write down information about these pieces.

For example, normally the piston, shaft, cylinder liner and crankshaft costs 50 reais each (10 dollars), which gives me a cost of 200 reais, but for some reason the same seller (or others) sells the complete set for 600 reais or more for the kit containing all pieces.

And I found some sellers giving a really cheap price for a group of pieces, like 2 pairs of shafts and pistons for half the price of what it would cost if bought each one individually, but it doesn't give any kind of information on its dimensions.

So I stay at risk of buying a bunch of expensive stuff that may or may not be compatible.

Which means I will have to take even longer to figure out the dimensions for this monster of oil pump.

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