Pseudotectonic

Introduction: The lost art of capacitors in airsoft The mythical powers of "capacitor banks" is not a new idea in airsoft, but the original sources and theories are lost in time, with only faint forum posts remain (all the links are dead in https://www.airsoftsniperforum.com/threads/capacitor-banks-revisited.8688/). In my pursuit of the ultimate trigger response in AEG, power supply remains a big unresolved issue because batteries (LiPo or NiMH) do not really give enough oomph for lack of a better word. We need something better, I thought, we need supercapacitors. And so I set out to rediscover the elementals of such dark magic from scratch (but based on the same principles). And I believe I have revived this magic which I will share my formula below. And dare I say, the surface of this dark art has not really been scratched, because the predecessors either did not use enough capacity (some examples were in the order of millifarads which is not nearly enough), and did not really use the correct type of supercaps (stacked coin cells hybrid types are not capable of high amps). And perhaps the right modules were not available until very recently, so this study will also represent a fresh look into this subject. If you want the bottom line: Why supercaps at all, isn't LiPo good enough? In short (excuse the pun), LiPo cannot provide sufficient peak current for the amp spikes during start of motor which is often in the region of 45-60 A. These micro-events of shorts (from the perspective of the battery) is also a main pathology of LiPo degrading and swelling over time. These spikes happen every shot in semi, and in the first shots in full-auto. This status quo practice of relying on abusing LiPo as sacrifice for performance does not sit well with me, because firstly it is electrically primitive, and secondly it is a safety risk in this toy gun industry that I think is unnecessary and should be done away with, at least as much as possible. The whole premise of using supercaps is to provide a voltage reservoir for surge power during these initial amp spikes. This is needed because these amp spike often exceed the capabilities of the battery (even LiPo) and the batteries drops voltage in response (for milliseconds) and unable to feed all the current needed for this initial spin-up of the motor. In theory, it can achieve the following: Surge power for much more responsive motor, resulting in snappier trigger response. Stabilised voltage supply for full-auto, resulting in better ROF. Protecting batteries from surge currents, prolonging their lifespan and minimise risks of LiPo fire. My evidence and theorisations are as follows. What is the actual energy requirement? To begin to figure out the solution, we need to ask, what is the minimum capacity to be effective? We can analyse these two graphs from airsoftlab.eu for theorycrafting. http://www.airsoftlab.eu/docs/experiments/motor_current/ To figure out the ballpark of energy levels we are talking about, I have picked two cases representative of a high stress build (with a 16 TPA motor) and a more optimal build (with a 28 TPA). The first graph is with 16 TPA motor, SP130, 13:1, to illustrate a typical suboptimal setup with a low torque motor paired with a high stress spring and gear ratio. The second graph is with a more comfortable 28 TPA motor with SP130 and 13:1 to show a more efficient setup. Just by eyeballing the graphs (and the blog), we can character these spikes (and the energy required to tame them) to be about 45A to 60A, for a duration of about 60ms. 16 TPA: 28 TPA: What do the numbers mean? There is a simple answer, and a more complex one. A simplistic way to translate this to farad (the capacity we need), using the 16 TPA setup as example, 60A for 60ms is 3.6 coulomb, which at 11.1V is about 0.324 F. For the 28 TPA example, this would be 2.7 coulomb, at 11.1 V this is 0.243 F. Therefore we can say our ballpark figure is about 0.25 F to 0.33 F as a minimum target. If we are aiming to create a unit that can work with worst case scenario, let's go with 0.33 F. However because supercaps discharge their voltage linearly (meaning their 11.1 V drops down to zero as it discharges over the 60 ms), we can think of it as sharing the workload with the battery in a 1:1 ratio (this is very simplified), meaning it is only doing half of the work while the batteries still need to supply the other half of the current (which is a big improvement already). Here is a prediction: In this predicted scenario, the amp spike seen by the battery should be reduced to less than half, because the supercaps will react faster to supply the spike, but as the supercap runs out of voltage, the battery will notice the difference in voltage and catch up, eventually supplying the full load in full-auto, but at a much improved stability. And as the trigger is released, the current stops, the supercaps are charged up again to battery voltage as the battery recovers from voltage sag. We can offload even more work from the batteries if we multiply the supercap capacity (say 3 times, to 1 F) so the they will perform in a 3:1 relationship i.e. 75% of the work are done by supercaps, which will stabilise the current even more. If we go bigger, say 1.66 F, the ratio will be 5:1, or 83% of work being done by supercaps. (The actual result will probably be better, the ratios e.g. 1:1 at 0.33 F are just conservative notional numbers I made up for ease of explanation. Supercaps are more responsive than batteries, and the overall lowered battery stress should further reduce overall voltage sag, so the battery should see less than 50% of the peak current, but I don't have the equipments to proof this hypothesis.) So let's say our notional baseline is 0.33 F, now we just need to implement this theory. Designing a supercaps unit Here is our goal: 1. Supercaps with total capacity of 0.33 F or more, bigger the better. 2. Voltage should be ok for airsoft usage. (Say a fully charged 11.1 V LiPo is around 12.6 V) 3. Overall size to be small enough to fit in a typical buffer tube, with room for cable management for most cases. Smaller the better. 4. (Bonus feature) built-in safety to drain residue voltage when unplugged. 5. (Bonus feature) LED to indicate presence of voltage. The obvious (and probably the only viable) strategy is to use 3 no. of 5-6 V supercaps in series to give us a 15-18 V headroom for the maximum 12.6 V we are expecting from a fully charged 11.1. The first problem is selection of supercaps. The second problem is designing the whole package that can physically fit inside the buffer tube. Long story short, here is my blueprint: (Just connect the supercaps in series, and then parallel with the batteries, I don't have a drawing) The Eaton supercaps I am using are the highest capacity that can still fit inside a typical buffer tube and wiring, and with one of the better ESR in its class, and can theoretically suffer 115 A of thermals over 60 ms, and tested to MIL-STD 202G for shock and vibration. They are wired (I'm using some fancy SPEC 44 16 awg wires) to a connector that goes between the AEG wire and battery wire, so it is completely plug and play, and removable for safety and for storage. It can in fact be stacked up (if you have multiple units) to give extra performance. For extra safety I have included a bleeder resistor to discharge the residue voltage in maximum 3 hours after it is unplugged. Also for safety (and aesthetics) I added an LED for visual indication of voltage presence. I am tempted to call it the PASTA 1000 (Pseudotectonic Advanced SupercapaciTor Array 1000 mF) but any suggestions welcome. Here is what it looks like in real life: Testing AEG: Specna E-19, completely stock (which has an X-ASR mosfet preinstalled.) Battery: 9.6 V NiMH, fully charged, measuring about 11.32 V when testing. This is just a simple A/B test to see if the supercaps work at all. I will simply alternate between plugging and unplugging the supercaps several times, then take measurements with groups of 6 to 7 shots, until the data are fairly consistent and/or a pattern can be identified. The groups are measured in Audacity and averaged and rounded to nearest millisecond. Also note I am not testing with any magazine inserted because A. that is not going to make massive difference either way and B. it is one less variable to worry about and C. if a BB goes off it is going to affect my measurements with sound. The results: Stock setup (without supercaps), group #1: Trigger response: from trigger action = 83 ms, from motor spin-up = [data missing] ROF: ~17.17 RPS With supercaps, group #1: Trigger response: from trigger action = 81 ms, from motor spin-up = 57 ms ROF: ~17.48 RPS (+1.8%) Stock #2: (I stopped measuring full-auto because it is getting too loud for the neighbours) Trigger response: from trigger action = 96 ms, from motor spin-up = 64 ms With supercaps #2: Trigger response: from trigger action = 74 ms (-23%), from motor spin-up = 62 ms (-3%) Stock #3: Trigger response: from trigger action = 90 ms (+22%), from motor spin-up = 69 ms (+11%) With supercaps #3: Trigger reponse from trigger action = 71 ms (-21%), from motor spin-up = 62 ms (-10%) Stock #4: Trigger response: from trigger action = 84 ms (+18%), from motor spin-up = 68 ms (+10%) With supercaps #4: Trigger response: from trigger action = 76 ms (-10%), from motor spin-up = 62 ms (-9%) Stock #5: Trigger response: from trigger action = 80 ms (+5%), from motor spin-up = 69 ms (+11%) With supercaps #5: Trigger response: from trigger action = 75 ms (-6%), from motor spin-up = 61 ms (-12%) Analysis of results: Definitely a noticeable audio difference in trigger response. The only way to describe it is it sounds more "instant" and there is less of the spin-up whine. I am not sure why the groups vary quite a bit (maybe battery and/or gearbox settling) but I think it is fair to say the supercaps are making a difference. If we average the data after group #3, with supercaps, the overall trigger response is about 14% improved, with the cycling time from motor spin-up is remarkably consistent at about 11% improved. The shorter lag time from trigger action to motor spin-up can be explained by the voltage stability provided by the supercaps. Overall I didn't know what to expect but I would say 14% improved trigger response is pretty good. It is definitely not a negligible difference, and definitely noticeable when compared side by side. But going by feel alone, it definitely feels a bit more snappy. ROF is probably improved a little bit, but more testing needed. The installation: This may be the only draw back. To actually fit the unit inside the buffer tube along with the X-ASR is a massive hassle, which I have to actually remove the original long heat shrink around the three wires to get them to flex, and re-crimp two out of three of the spade connectors to the X-ASR because they were damaged by too much bending. And even when the supercaps are in, it is still very stuck and you need to wrestle the wires to get the battery on and close the butt plate. Although I have done it with the stock fully collapsed and if I install it with the stock a few positions out, it will be easy. Once it's on, it works. But it is definitely not ideal if you have any in-line mosfet like mine. However if you use a proper mosfet inside the gearbox and just have wires in the buffer tube, it should fit very easily, potentially upping the supercaps to 5 F ones for even better trigger response. There is no noticeable sparks or heat or anything when install and in use. It simply lights up when you plug it in and it just works with zero drama. Here is how it looks like installed, with a fully collapsed stock, and without the stock: (it barely fits) To uninstall: If the battery is disconnected with just the supercaps plugged into the gun, the gun will barely able to do one shot and the second shot will be stopped by the mosfet because the voltage will have dropped too low. This is just as expected and fairly consistent with the maths. The LED: When you unplug everything, the LED stays on but slowly dims down over the course of about an hour (just as designed). This shows the draining resistor and the LED are all working as intended. I could also feel zero heat from the resistor, which is great and again matching expectation. The LED still visibly faintly glows even at as low as 2 V so it works perfectly for its purpose as a voltage indicator. The red LED is pretty to look at, although I might change the colour to something like blue or green, because the red can be mistaken as error from the mosfet. I might also move it to the "top" side of the "plug". Conclusion of experiment: The prove of concept is a success. Most importantly there is certainly a performance benefit (14% in my test). All the maths check out. The unit is fully functional and fully match the expectations. It literally is plug-and-play. The installation can be a hassle for wire management but that is purely down to physical space and should not be a problem if you are not using in-line mosfet. Conclusions and speculations More testing is needed with other setups, if you would like one for testing I can make you a copy for a fee. The tech tree can potentially branch into AKs or other platforms or even external compartments, but I don't have any of these for development. Here is a summary of what this device can do. The biggest feature for me is safety, because when the LiPo (or any battery) is shielded from stress they are much less likely to puff up over time and starting a fire. Another key thing is of course the performance. It works very well in my very first little experiment. Electrically the overall voltage floor and current ceiling is improved. Adding supercaps is a bit like transitioning from NiMH to LiPo, but on steroids. There is also where the drawbacks are, because a mosfet is probably a good idea for such power, and if you want to collapse the butt stock you will need a more advanced mosfet that sits inside the gearbox rather than the buffer tube, for cable management reasons. (If you copy what I did you will risk breaking some wires) In terms of use cases, it will benefit NiMH the most because the performance is suddenly brought closer to that of LiPo because the performance gap is effectively closed, making NiMH a viable option again. In fact it makes NiMH better than LiPo because NiMH is much safer. This is also a must if you are chasing the state-of-the-art trigger response or battery efficiency in any build. It will also help with cold weather performance. And the best thing is, this is essentially a "free upgrade" because it is an entirely new component added to the system, it does not replace or compete with any existing parts, and it doesn't need any complicated installation, it is literally plug-and-play. The only downside for now is with wire management inside the buffer tube to make room for it. I am not sure if there is enough space for guns other than an M4 but maybe you can find creative ways to fit it e.g. longer wires. This can potentially benefit rental fleets because it is the easiest upgrade possible with zero overhead on tech, plus it makes your NiMH or LiPo inventory much safer and longer lasting. The savings in overhead for battery management could be worth the investment. And when a gun dies you can very easily transplant it to the replacement gun. In theory, you can actually stack multiple units for extra performance (the only problem is finding the space to put them). Conclusion is, and I am probably biased, supercaps could be the next best thing in airsoft. If the space problem can be resolved. Please do comment if you spot any issues in the theory or in the blueprint. Thank you for reading.

If you are talking about AEGs specifically, you are really talking about an M4 without the appearance of an M4 If you take all the functional parts out and put it back together, it would still look somewhat like an M4 You can go crazy with the design of the externals, you can even do one of those 3d printed guns like https://github.com/HYBRIDAIRSOFT/MOSQUITO But in essence, it will be an M4, because an M4 is close to being the most practical AEG you can get considering the parts available If you have unlimited budget and designing the whole mechanism from zero, of course that is another topic

I don't see the point of mixing bushing and bearings because as per airsoft physics, the differences and variables affecting the three gears do not make them considerably different from one another in terms of the type of loading and the amount of force behind them The different surface finish on the axles themselves with different gears already makes it impossible to work out the precise newtons applying on a bearing because if it is anything but perfect it is going to have a bit of wobble, and the brand of bearing alone (and the size, and the amount and type of grease, heck even the amount of dust exposed) will determine your shock load capacity of the bearing which is what ultimately makes using bearing worth while for the speed advantage But since every particular setup is different, even the best bearings you can find will have a risk of exploding, again because of airsoft physics and tolerances If you have to be mathematical, the bevel gear spins the most, followed by spur and sector gear, so the bevel gear will benefit the most from the less resistance from a bearing, in theory, but if you are willing to take the risk of exploding bearings there is no reason to not use it on all three gears So it comes down to whether your setup is so marginal that your motor and battery cannot handle the negligible amount of extra resistance from bushings that you have to sneak in one or two or three bearings to lower the resistance, and choosing how many bearings to use is just a matter of risk management, because more bearings = more points of failure In my opinion, bushings work fine, they are more reliable, the speed difference is not worth the risks of failing bearings because they fail catastrophically in almost all cases If you want to put in bearings, I would start with putting on the bevel gear first, then spur, then sector gear, but in reality it does not matter because again, airsoft physics and tolerances is a pure chaotic mess therefore there is no theorycrafting possible, in reality it might even come down to the finishes of your particular gearbox and whether your shimming is making one of the gears rubbing on any one of the bearings, for example, so again, no theorycrafting is possible, because it is ultimately up to you and two million other variables

Yes you can still play with it without UKARA The question is only related to how you got it in the first place The only legal route would be she give it to you as a gift But after you got it, you can go to a field and play with it no problem

DDM4 PDW pictured with a light and red dot it's the DD pistol grip that gave it away

are you going to throw in some gas and BB? and eye protection? and extra mags? and a plate carrier to carry those mags? and a helmet to go with the plate carrier? and a full BDU to go with the helmet? and a rifle to go with the BDU? etc

The reason I didn't lap it all the way flat was it will probably take down too much and weaken the flange that holds it in place in the gearbox, and also my shims are really just half the size of the bushing, so it is just the inner half of the circle it is resting on, and because there are not much axial load all it needs to do is keep the gear aligned and nudge it when it is off, and having the peaks removed will help the shim does its job and remove most of the point loads from the poor finish against the shim to prevent shim deformation, and there will be grease anyway so yeah, a bit of grooves are good for grease retention I've also polished the gears with tiny amount of Peek (the metal polish) and a dremel buffing wheel on a drill, just to remove the factor sharp corners on the teeth generally

The nominal capacity is usually measured with 0.2 C down to a lowest acceptable voltage like 2.75 V, it is never rated to discharge to 0 V because below the 2.75 V (or whatever they decide to be the cut-off voltage) it is irrelevant for all intent and purposes In that graph for example, Samsung decides the end voltage to be 2.5 V and actually has two capacity rating for 0.2 C and 10 A (which is about 0.4 C), and they are rated on paper to be 2500 mAh and 2450 mAh respectively (and the actual measurements confirm roughly with these numbers) https://www.powerstream.com/p/INR18650-25R-datasheet.pdf But every manufacturer measures it differently, some measures with higher C, some has different cut-offs, but the paper capacity is always rated to the cut-off voltage and not to zero

in my opinion only the AK and MP5 can do CQB and woodland well, and between the two it is personal preference

a few days is nothing to worry about some chargers have discharge function

He is right, if you discharge below ~3.0 V per cell you are just going to kill your LiPo, and since you drop down to ~3.0 V sooner with a higher C, you get less usable mAh out of the battery. Extrapolating to 0 V is irrelevant, even if you can do that, which you can't, because if we are drawing our own lines, I could just extrapolate the higher C to drop to 0 sooner, which is probably more likely to be the case.

I noticed on the SHS/Rocket bushings the factory surface finish is really inconsistent. Some are very rough but some are relatively smooth. This difference can be literally highlighted with some lapping. What I am doing here is used a 7000 grit paper and then 3M 0.3 micron lapping film sitting on a piece of marbel for some basic lapping. I am not aiming for any super precision here but only aiming to knock down the high points on a reasonably flat surface. If I were to lap it all completely flat it will probably take away too much material. You can actually feel the difference by running your fingernail on it in circular motion. In the first picture is the bushings in various stages of lapping process. The second picture is when they are done I am trying to grade and pair them up, which I am going to use the rough ones for sector gear and smoothest ones for bevel. Just because bevel spins the most. It may not look much but judging by feel of fingernail, it is already massively improved over factory finish. In theory it should at least reduce a tiny little bit of friction and helps with the breaking-in.

That was just a generic LiPo discharge curve from https://www.dnkpower.com/lithium-polymer-battery-guide/ You will get less overall mAh regardless of temperature with bigger current, as well as a bigger voltage sag the entire way So in any case, bigger capacity battery is always bigger because it represents a smaller C at any given current and will have less voltage sag, which is really what can affect the feel of the motor

Ackchually that is true, for example:

Ah = Amp-hour (capacity), but more commonly in mAh (milliamp-hour) which is 0.001 Ah A = Amp (current)

new tappet plate - is it sliding without friction? sometimes new tappet plates don't slide well, might be too thick etc

sounds like it's the magazine have you tried opening up the magazine and clean it

Public liability insurance is the legal requirement for airsoft skirmishing and UKARA site registration so if the site appears on the UKARA website, they will have public liability insurance. As far as I know, employer's insurance can be displayed "electronically", which might be simply an email I reckon

Air weapon (a firearm) and airsoft (not a firearm) are totally separate class of objects under Firearms Act. Airsoft being its own category is not considered a firearm. Depending on the exact wording of your sentence, a firearms ban probably means you cannot touch air weapons, but you can still play airsoft because airsoft is not firearm. From your description it sounds like you were done for the air rifles, but not for airsoft. Your "bb guns" may be air weapons if your BB is the metal kind of BBs and not the 6mm plastic airsoft BBs.

Still trying to figure out what this magical transparent material is that can drop BBs straight down on impact https://www.youtube.com/watch?v=rokdTjypBg4&t=90s https://www.youtube.com/watch?v=ek9A6fgiKAE&t=37 My current guess is some sort of 3 mm PVC sheet but not entirely sure, perhaps the way it is held around the edge with velcro also has something to do with it

You can use Audacity to measure trigger response or ROF or even for general diagnostic by getting an idea of how it cycles. Basically you can set it to record whatever sound you computer is playing, and you just click record and go watch a video and stop recording once you get the sound you need. And then here is my method of interpretation and it works for comparison purposes:

@Leo Greer From my measurement that is about 39 ms trigger response The best I have seen in all of the internets is a 19 ms setup with a 28 TPA and m130 spring, unknown gear ratio (could be even 18:1) but that guy had somehow gotten a precocking that is literally the piston just sitting on the very last teeth before release, and the sound is just like a spring rifle because it really sounds instantaneous, sadly the vid was deleted and I could only dig out my reddit PMs for the numbers, but that was the theoretical peak of trigger response and I am so glad to have witnessed it, and it was better than every single youtube video or clips of people showing their trigger response, so that is the ceiling to aim for if there is one

yes

If the image doesn't load for any reason here is a direct link to imgur https://i.imgur.com/gFEvWkO.png On the subject of polishing, I wonder if anyone has gone so far as to polishing the gears and piston teeth with metal polish like autosol or something so it improves the meshing characteristics