Cutting Spring= Higher ROF?

[Stealthbomber]

I think there is some inertial advatage to a variable rate spring, but I think it's uber small...but I do install springs with the tighter coils on the spring guide, so they don't have to fly around with the piston. Every little bit helps, I suppose.

<{POST_SNAPBACK}>

TBH, that would be my conclusion too. I doubt any increase in performance would actually be down to the shorter spring. It'd be due to the ability of the motor to spin-up quicker from rest and, hopefully, that advantage would be slightly more than you'd lose when the motor, subsequently, has to compress the stiffer coils.

 

Honestly, I'm kind of a lazy airsofter. I tend to go for consistancy and reliability rather than outright ROF or power.

I don't bother to swiss-cheese pistons or even run my guns on 9.6v.

 

I guess it's kind of like tuning an F1 car. There are a bunch of tiny improvements you can make to the car which, in isolation, are pointless but when you add them all together you find the car knocks half a second off its lap time.

 

Similarly, in an AEG, there are a bunch of these tricks you can do and (importantly) none of them achieve much in isolation. If you add them all together, however, you get a useful improvement.

[Tecro]

That article I mentioned definitely didn't talk about huge ROF improvements, but it's still a decent improvement. Still looking for the article, by the way.

 

Correct, by the end the spring is providing the same number of Joules. But in a progressive rate spring or cut spring, it's exerting force for a shorter period. And that means that the motor can turn faster in the first part of the cycle, where there's less resistance, which means that the whole cycle's time gets cut down a bit.

 

You may be right about the springs helping to remove inertia, but I doubt it. Later in the compression cycle, they increase the force much more quickly. I dunno.

 

And in retrospect, I really don't think that such springs provide more resistance to the motor at the end of the cycle. The graphs in the article showed a steeper increase in force at the end of the cycle, or a greater rate. But the actual force the spring applies never exceeds that of a regular spring. It just waits a while and builds up to full force more quickly.

 

Oh, and one more thing. I didn't want to bring it into the discussion, but it might be necessary...the problem is that the shorter spring won't apply any force at the end of the piston's cycle, where it fires the BB. Simply because the spring is too short to expand any further. So the question is, would you need to cover up the vents in the cylinder? Otherwise the BB would still be in the barrel at the end of the spring's decompression.

 

As far as I can tell, an unvented cylinder with a strong spring cut short would also get more power. Really. Because with a standard spring, vented configuration, only part of the spring's expansion cycle would be used to push air for firing the BB. With this, the full expansion of the string is used, allowing for more power. I think.

 

I'm also a safe player when it comes to upgrades, at least power upgrades. I would prefer to use harmless mods to get better performance, provided they don't really decrease the lifespan of the gun. Major, excessive spring upgrades and 9.6+ volt batteries are out of the question.

[Sale]

Oh, and one more thing.  I didn't want to bring it into the discussion, but it might be necessary...the problem is that the shorter spring won't apply any force at the end of the piston's cycle, where it fires the BB.  Simply because the spring is too short to expand any further.  So the question is, would you need to cover up the vents in the cylinder?  Otherwise the BB would still be in the barrel at the end of the spring's decompression.

I don't think they were going to cut it that short.

 

Has anyone come to think that progressive spring might also work the other way around? I mean when the piston starts to accelerate forward, the spring is giving a harder shove, but when it's moving, the loose part of the spring (which was easy for the motor to compress in the beginning cycle) only keeps the piston moving because it has gained a stable speed already.

 

-Sale

[Glenn]

I think that is the natural by product of variable rate springs - you get nice hard shove to get the BB moving and past the hop, when it needs the most help.

 

And Tecro, a variable rate spring must have greater stiffness than a linear spring at some point, else it cannot store the same amount of energy.

[Tecro]

And Tecro, a variable rate spring must have greater stiffness than a linear spring at some point, else it cannot store the same amount of energy.

<{POST_SNAPBACK}>

True. But I think that was a terminology error on my part...

 

It gets greater ROF because it stores less energy. However, the final strength should be same as that of the original spring. While it's shorter, the spring has a greater rate and reaches a certain amount of force in that shorter distance. So it doesn't actually provide any more resistance at any one point in time, and it also provides less resistance over time because it kicks in later.

 

About Sale's point, I've never thought about the progressive spring's benefit that way, so I don't know.

 

Has anybody read that article I referred to? I'm still looking, but can't find it. It's driving me crazy!

[Glenn]

Tecro, I don't think you're quite understanding what I'm saying.

 

The spring must store the same amount of energy as an equivelent linear spring - or the two springs would not be equivelent.

 

If the variable rate spring stored less energy, it would deliver less energy to the BB, which isn't what we want. We're talking about two springs that store the same energy, so the varialbe rate spring must, at some point, provide more resistance than the the linear spring.

 

Imagine compressing a linear spring - you add energy by squishing it, and for the entire length you squish it, you just keep adding up the energy.

 

Now think of a variabl rate spring - in the begining, it doesn't take much energy to squish it -so the motor can more easily beign to compress it - then later, it becomes stiffer, and it takes more energy to compress it. The idea is for the less energy part + the more energy part = total energy in linear spring. You can't add less + less and get the same energy as a stiffer linear spring. Conservation of energy.

 

The increased ROF is a result of the the way electric motors work. Look at the graphs I posted -they've got less torque early on, and so they can't push a heavy load as fast when they're starting up. Lighten the load with a variable spring, and they can spin up faster, permitting them to gain the required torque to compress the stiffer stage of the spring.

 

And the variable rate spring doesn't half to be shorter, either, though they certainly could be.

[Stealthbomber]

This is what happens when a bored person has access to a spreadsheet.

 

I was trying to think of a way to express this idea so I cobbled up a quick graph:-

 

 

Cos the non-linear (or shorter) spring is giving the motor an easier time, it can spin-up and start the piston moving easily, whereas the motor is struggling to get started with the linear (or longer) spring.

 

Towards the end of the cycle you can see that the non linear spring is giving the motor a pretty hard time but, by then, it's already so far ahead of the linear spring that it struggles over the finish line first.

 

That's about as clear as I can make it.

 

Incidentally, in case it needs saying, the numbers on that graph are all notional. They're just there to demonstrate the idea.

[Sale]

Stealthbomber: I believe progressive springs work in a completely opposite way. I had to look at that chart a couple of times to be sure what you meant. (EDIT: And the third drunken view I had revealed the point. So we agree 100%.)

 

A progressive spring has less pre-tension and it's weaker in the beginning, so that's what lets the motor gain RPM. Once it has some inertia (and the gears as well), the stiff part of the spring kicks in. In the end the progressive spring comes out as a winner.

 

Seriously, I usually don't buy what manufacturers tell me but if they are selling a progressive spring when they just as well could make a linear spring for less and still sell it for the same price, I tend to believe progressive compression has real advantages to it, and they are calculated and tested accurately for each power level. If you would actually gain something from cutting an M120 to M100 level, surely Systema would already make them that way.

 

-Sale

[Stealthbomber]

Stealthbomber: I believe progressive springs work in a completely opposite way. I had to look at that chart a couple of times to be sure what you meant.

<{POST_SNAPBACK}>

Hehe. TBH, I was debating which way around to do that graph. I decided to do it so it's showing what percentage wound the piston is rather than what percentage load is on the spring.

I know what you're saying but it does work out the same. For example, when the piston is wound 50% of the way back the spring will probably only be 20% loaded. It's only in the final bit of winding that most of the tensioning occurs.

 

If you look at something like a Systema spring I bet you could actually work this out with some degree of accuracy based on how much of the spring has wide coils and how much has tight coils.

 

Sorry for the confusion but I think we're looking at the same thing but from different POVs.

[Sale]

Well I edited my reply so we don't have a confusion now.

 

Gonna get some sleep. ->

[Glenn]

Nice graphs, they look spot on for some arbitrary springs.

[Tecro]

The graph [edit, the first graph] below plots something different...the force vs. compression distance. Big picture when you click on it, but very low in size -> fast loading (I hope) for 56K.

 

The thing about AEGs is that the maximum force > total energy when determining the FPS. I absolutely agree that a variable rate spring stores less energy--which is precisely why it takes less energy to compress and thus less time to compress.

 

The key is that variable rate springs get extra ROF while sacrificing minimal FPS. Get a slightly stronger spring to maintain the FPS if you want, although I'm sure the net FPS loss is unnoticeable. I don't have firsthand proof of it, though.

 

That's the key...the fact that the force exerted at the end of compression is more important than the total energy. And in the graph, the energy can be interpreted as the area below each of the lines, because energy/work (?) is force * distance.

 

Note that the progressive/variable rate springs do not require the motor to apply extra force at the end of the cycle. The amount of force required increases quicker at the end, so the slope of the line is steeper, but the actual force is never greater.

 

In a few moments, I'll show what happens with a shortened spring. Using a second graph...

 

EDIT: Second graph up, same thing except "compression distance" has been changed to "compression time." For the graph, assume that the progressive spring isn't any faster than the linear spring.

[Stealthbomber]

Those graphs haven't been thought through properly.

 

The first one doesn't take account of the fact that the motor will struggle to start winding a linear spring.

Other than that, it's showing exactly the same thing that my graph shows but, as I already said, I graphed how much the piston is wound rather than the load on the spring.

 

The second graph doesn't take into account that a short spring capable of imparting the same energy as a long one MUST be harder to wind.

Your graph shows a long spring being wound (by a given motor/battery) in a set time.

It then shows a shorter, tougher, spring starting to be wound later and then, somehow, wound faster.

 

That's impossible.

[Tecro]

The first one doesn't take account of the fact that the motor will struggle to start winding a linear spring.

<{POST_SNAPBACK}>

As I said, I didn't address the total compression time in either of the graphs. Just the percentage of compression time.

 

Other than that, it's showing exactly the same thing that my graph shows but, as I already said, I graphed how much the piston is wound rather than the load on the spring.

<{POST_SNAPBACK}>

But as far as the BB is concerned, the amount that the piston is wound is irrelevant. Only the force applied to it affects the power.

 

Also, on your graph, the advantage of a variable rate spring should be even more obvious. Once again, the shortened or progressive spring will never apply more force than a standard spring--but the force will be equal at the end. Thus, throughout the cycle, the motor should be capable of compressing the spring faster than it compresses the regular spring, except at the end. In your graph, the slope of the progressive spring's line should never be lesser than the slope of the regular spring. The slopes should be equal at the end because an equal amount of force is applied at the end.

 

The second graph doesn't take into account that a short spring capable of imparting the same energy as a long one MUST be harder to wind.

<{POST_SNAPBACK}>

But the whole idea is that the shorter spring does not hold as much energy as a standard spring. It does, however, have the same maximum force. And as I said, it's that maximum force that is most important.

 

What I said has been ignored. If it's wrong, then that's also fine, but at least it should be addressed. I'm restating it:

"The thing about AEGs is that the maximum force > total energy when determining the FPS. I absolutely agree that a variable rate spring stores less energy--which is precisely why it takes less energy to compress and thus less time to compress.

 

"The key is that variable rate springs get extra ROF while sacrificing minimal FPS. Get a slightly stronger spring to maintain the FPS if you want, although I'm sure the net FPS loss is unnoticeable. I don't have firsthand proof of it, though.

 

"That's the key...the fact that the force exerted at the end of compression is more important than the total energy. And in the graph, the energy can be interpreted as the area below each of the lines, because energy/work (?) is force * distance."

[Glenn]

Tecro...you're all kinds of backwards here.

Also, on your graph, the advantage of a variable rate spring should be even more obvious.  Once again, the shortened or progressive spring will never apply more force than a standard spring--but the force will be equal at the end.  Thus, throughout the cycle, the motor should be capable of compressing the spring faster than it compresses the regular spring, except at the end.  In your graph, the slope of the progressive spring's line should never be lesser than the slope of the regular spring.  The slopes should be equal at the end because an equal amount of force is applied at the end.

But the whole idea is that the shorter spring does not hold as much energy as a standard spring.  It does, however, have the same maximum force.  And as I said, it's that maximum force that is most important.

<{POST_SNAPBACK}>

 

In order to produce the same muzzle energy, springs must store approximately the same energy. Variable, linear, short long, they must.

 

"Max force" does not determine velocity. Total stored energy does. Reread what has been written...I don't think you wuite understand how a variable rate spring works. Such a spring moves between less and more stiff than a linear spring, it does not simply ramp up from less to the same stiffness as a linear spring. If it did, it'd be a considerably weaker spring. This is amaziningly simple math. Your above quote is essentially entirely wrong.

 

You're totally skipping conservation of energy, and you're leaving out the dynamics of electric motor operation. You're saying things happen that are, to quote Stealth, impossible.

 

What you've got almost right is the bit about shorter springs. If you grab any old linear spring and chop it, it'll hold the same amount energy at a given compression. At a given length, though, the shorter spring holds less. Similarly, the springs produce the same force when compressed the same amount, but when their total length is made to be the same, the longer spring has compressed more, and thus exerts more force. I hope you see what I'm saying, it isn't exactely the clearest concept to see written out.

 

But, you're basically all wrong. That said, this is a good friendly debate, and I appreciate that nobody is yelling yet:D

[onidemonXLR]

so, in simpletons terms, i could get a really stiff spring that would get me higher than acceptable (above 400) FPS for a woodland game, then just hack a few coils off, and have a field regulation spring (300-350) with a really high ROF

 

Oni

[Glenn]

Pretty much, yeah. It might not be the best idea, given the challenge of determining how much to cut off to get the desired velocity and maintain sufficient length, not to mention dealing with the cut end of the spring which is no longer flatwound. But you could do it if you really wanted:D

[Stealthbomber]

What I said has been ignored.  If it's wrong, then that's also fine, but at least it should be addressed.  I'm restating it:

"The thing about AEGs is that the maximum force > total energy when determining the FPS.

Personally, if I ignored that statement it's because I don't understand it.

You're saying "Maximum force is greater than total energy when determining FPS"?

I just don't know what that means.

Are you pointing out that the gearbox is an enegry-inefficient system?

That there is more than 1J of electrical energy used to wind a spring capable of storing 1J of kinetic energy?

 

I absolutely agree that a variable rate spring stores less energy--which is precisely why it takes less energy to compress and thus less time to compress.

But you're the only one suggesting this.

Both Glenn and myself are of the opinion that the reason a variable-rate spring can wind faster is because it's easier for an electric motor to begin winding from rest.

 

To use another dodgy metaphor, let's imagine we had to push a heavy cart up a steep hill.

If the hill was steep all the way up you might not be able to even start it moving.

If the hill started off with a gentle slope you'll be able to start it moving easier and get much further up the hill even as the incline steepened.

 

"The key is that variable rate springs get extra ROF while sacrificing minimal FPS. Get a slightly stronger spring to maintain the FPS if you want, although I'm sure the net FPS loss is unnoticeable. I don't have firsthand proof of it, though.

 

"That's the key...the fact that the force exerted at the end of compression is more important than the total energy. And in the graph, the energy can be interpreted as the area below each of the lines, because energy/work (?) is force * distance."

<{POST_SNAPBACK}>

I'm just not sure you're "getting it".

If you take 2 identical springs, both 1J rated, and lop 6 coils off one of them then that spring will no longer be a 1J spring.

In that case, of course the shorter spring will be easier to wind and yield a higher FPS.

I don't think anybody's disputing that.

 

If you were to compare 2 linear springs which both yeilded 1J power, one 25cm long and the other 15cm long, then the shorter spring would HAVE to be harder than the longer spring. In order to store the same energy in a shorter spring, it must be tougher.

This is the case the OP is discussing and, personally, I doubt that (if both springs were linear) there would be a vast difference in the ROF.

There might be a tiny advantage with a shorter spring because (as with the non-linear spring) the motor will have an easy time at the start of the cycle while it is spinning up.

That advantage MUST be paid for further along the cycle though. The shorter spring WILL be tougher to wind but, hopefully, the motor can deal with it better once it has reached full speed. As a result, you get a small nett advantage in ROF.

[Tecro]

[EDIT]Heh, longer post than expected. If I left something out, please let me know. Thanks. [/EDIT]

 

Personally, if I ignored that statement it's because I don't understand it.

You're saying "Maximum force is greater than total energy when determining FPS"? unsure.gif

I just don't know what that means.

Glenn understands what I'm saying, even if he doesn't agree...it's just conjecture after all. I'll get back to this.

 

I absolutely agree that a variable rate spring stores less energy--which is precisely why it takes less energy to compress and thus less time to compress.

 

But you're the only one suggesting this.

It's implied throughout the whole discussion. If there's a variable spring providing the same final force as a linear spring, then it has less energy because the force is small most of the time. Energy = Work = Force * Distance.

 

To use another dodgy metaphor, let's imagine we had to push a heavy cart up a steep hill.

If the hill was steep all the way up you might not be able to even start it moving.

If the hill started off with a gentle slope you'll be able to start it moving easier and get much further up the hill even as the incline steepened.

Correct. That's your take on it. But that's another thing I'll address in a bit...

 

But we can add some more to your metaphor. Let's say that the slope of the hill is the rate, that the altitude at any given time is the force, and that all the earth inside the hill is the energy. The linear hill has a constant slope. The progressive hill starts with a smaller slope, but that changes and the slope at the top is greater than the linear hill's slope.

 

Because the progressive hill has a smaller slope (rate) until the end, the altitude (the force) is lower than the linear hill. The slope (rate) is high at the end, allowing the altitude (force) to equal that of the linear hill. But there's less earth (energy) below your feet in the progressive hill, and less energy is needed to go to the top. Same as with my graph(s).

 

But you're saying that you need the slope (rate) to be massive at the end in order to allow the altitude (force) to be higher. That would allow the earth below (energy) to be equal. However, I'm saying you don't need to have that extra force from a stronger spring for more energy. Having enough force will get you the FPS, and you don't really need equivalent energy.

 

That's my take on it. I'll elaborate more in a bit.

 

If you take 2 identical springs, both 1J rated, and lop 6 coils off one of them then that spring will no longer be a 1J spring.

In that case, of course the shorter spring will be easier to wind and yield a higher FPS.

I don't think anybody's disputing that.

True, but that's assuming the springs are identical. What if the spring you cut was stronger? By "stronger," I mean it would have a higher rate and would be able to attain an equal force in a shorter distance. The rate is 0 at the beginning, and then there's a higher rate at the end. A full-length progressive spring is the same, with an increasing rate. This is one of the reasons your case appears wrong in my eyes.

 

If you were to compare 2 linear springs which both yeilded 1J power, one 25cm long and the other 15cm long, then the shorter spring would HAVE to be harder than the longer spring. In order to store the same energy in a shorter spring, it must be tougher.

I just want to clear up some confusion. A "tougher" spring has a greater rate, nothing else. It does not have greater force, as you can always compress further and get greater force. Unless the spring physically can't compress anymore due to space issues.

 

Spring rates are "delta load / total deflection," or "delta force / total distance." So a spring could have a rate of 2 pounds per inch. If you compress it 2 inches, you get 4 pounds of force; 6 inches, 12 pounds of force; 10 inches, 20 pounds of force; etc. A tougher spring has a greater rate, and reaches a certain force in less distance.

 

So your statement, "In order to store the same energy in a shorter spring, it must be tougher," is only true by default. In order to store the same force, it must be tougher, and in order to store the same energy, it must be tougher still. Which I do not think is necessary.

 

Okay, wrapping it all together.

 

I don't buy the "energy is more important than force" or the "it's the motor spinning up that counts" arguments. I'm not just resisting being convinced of it, I don't mind my points being taken apart.

1) The motor is already spinning. It might even be spinning faster before compression than during compression. Why? Because during full auto, it's still powering and turning the gears, making the teeth come back around to the piston. And it has no resistance then, so it should be going faster*. Unless the motor is going faster than optimal (which is not a case you guys brought up), it should be ready to handle a strong load from the spring from the start. And since progressive springs increase the ROF, this case I've brought up can't be true.

 

So in full auto, the motor is already spinning faster than ever. And in semi auto, ROF doesn't even exist.

 

2) When is the most force from the spring needed? At the beginning of decompression, as that's when it actually fights against the inertia of the BB. Remember your argument about how a vented cylinder lets the piston gather momentum to send the BB flying? That works because that extra (impulse) energy is needed at the beginning, when the BB has a ton of inertia.

 

The spring provides the most force when compressed the most. And if you accept my previous paragraph's argument, we can say that it is only the time of maximum force that the spring matters. A progressive or short spring usually doesn't provide as much force as a standard spring, but it does when fully compressed. That's why it can manage to get a similar FPS even without the same amount of energy.

 

Another reason why longer barrels and unvented cylinders fail to get extra power is that they implement the weakest part of the decompression cycle--the end. Yes, it's partly because the BB is already at high speed, but that might be different if the springs could apply their "maximum" force**. While compressed only 10% of their maximum compression, they only provide 10% of the force. And for a BB that's already moving fast, that bit of force is insignificant. So all this is just proving that the end of the cycle, where a standard spring is strongest, is insignificant.

 

3) Earlier in this thread, I mentioned that a shortened spring would be better because you likely wouldn't use a vented cylinder. Yes, you can say that removing the vents gives the standard spring an edge in terms of initial force on the BB, but the shortened spring makes up for that in a different way.

 

Although much of a standard spring's initial energy goes to giving momentum to the piston, much of it is wasted in the process. Energy that could have been used to propel the BB is being wasted through the vents. And this is energy from the part of the spring's cycle in which it is most compressed and provides the most force. This fact alone would decrease the power somewhat.

 

A shortened spring, on the other hand, uses its full cycle to propel the BB. It doesn't send air flying through the vents***. The spring is short enough that it doesn't displace more air (by volume) than the barrel contains, so it doesn't need vents. This means no wasted energy.

 

So even if you think that the total energy is more important than the maximum force, I hope this last argument convinces you. With a shortened spring, an AEG doesn't expel any more energy than it actually needs to, one way or another--either by making use of maximum force or by not wasting that energy.

 

* Remember Airsoft Mechanics' capacitors article? That works because it takes the energy wasted on the toothless part of the gear cycle and gives that energy to the compression part of the gear cycle. So there's plenty of energy to go around while the gears and piston aren't meshing.

 

** That's "maximum" because, as I said, the force can always be higher if you compress more.

 

*** In case somebody didn't know, standard springs are usually so long that the piston's volume is greater than the barrel's volume. Without cylinder vents, all the air inside the barrel would be displaced before the piston was completely forward, wasting air. A partial workaround is to use vents and get momentum built up in the piston--so the extra air is released before, not after, the BB leaves. But it's still wasting energy.

[Stealthbomber]

There's so much in there that I don't understand or don't agree with that I guess I'm done.

[Tecro]

Sorry...but I don't mind clearing up some stuff if you point it out. A bit of a tradeoff between complete clarity but really long, short but still not concise, or a complete garble of nonsense.

 

But seriously, I don't clarifying anything. I tend to write in a fairly unorganized and non-concise manner.

[Sale]

How about we trust the manufacturers to make the R&D. They make springs to be installed, not to be cut into pieces. To put it short: I don't believe for a second that if you cut an M120 spring to M100 level that the ROF would be better than starting straight away with an M100. On the contrary, it actually might even slow the ROF down, because when you cut coils off a strong spring it becomes more linear.

 

I think that progressive springs may hold less energy but still produce the same FPS, because the forward motion is different: It has a quick boost in the beginning, and then the remaining spring upholds that speed -> it is more efficient than a linear spring. For the reversed reason it is also easier to compress, so the ROF is better than with linear springs.

 

-Sale

[Tecro]

How about we trust the manufacturers to make the R&D. They make springs to be installed, not to be cut into pieces. To put it short: I don't believe for a second that if you cut an M120 spring to M100 level that the ROF would be better than starting straight away with an M100.

<{POST_SNAPBACK}>

I'd be willing to say that the only reason manufacturers bother with such long springs all the time is for compatibility. The length of the springs, pistons, and cylinders are really only used for long barrels. For shorter barrels, a shorter spring would actually be ideal; but that would mean a huge assortment of pistons, springs, and cylinders, all of different lengths.

 

You can already see this compatibility issue. There is a reason AEGs don't use massive PSG-1 parts with hugely vented cylinders--because it would waste energy and decrease the ROF. Manufacturers already know that there's no need to use a longer spring than necessary.

 

Vented cylinders, as I said, are just a workaround. A way to grab a little extra energy before it's wasted. But it's not nearly the same as directly addressing the problem by matching the spring/piston/cylinder to the barrel.

 

On the contrary, it actually might even slow the ROF down, because when you cut coils off a strong spring it becomes more linear.

<{POST_SNAPBACK}>

How would it become more linear? Assuming that the standard spring and the uncut M120 are both linear, they will stay linear even if they are cut. The M120's rate is higher though.

 

I think that progressive springs may hold less energy but still produce the same FPS, because the forward motion is different: It has a quick boost in the beginning, and then the remaining spring upholds that speed -> it is more efficient than a linear spring. For the reversed reason it is also easier to compress, so the ROF is better than with linear springs.

<{POST_SNAPBACK}>

Exactly. Shorter springs don't make the motor use any more energy than it needs to, increasing ROF.

[Sale]

I'm sorry but you really need to gain more experience before making statements like that. In another thread you mentioned never even using an upgraded spring. The free length of the spring is not the defining factor of its characteristics, because it's compressed in the same gearbox with the same piston and sector gear. Please show me a linear M120 spring to begin with and we can continue this. All major brands that I know of have progressive springs for every upgrade level.

 

As we've gone through before, vented cylinders allow shorter barrels to gain the same muzzle velocity as longer ones, with the same springs. I fail to see a problem there, because you're getting the same (or even better) ROF, same muzzle velocity... Where's the wasted energy?

 

What you're suggesting about shorter springs makes no sense, unless you would also shorten the piston stroke for a shorter barrel, and use a stiffer spring to make up for the difference. But even then the spring wouldn't need to be any different than other AEG springs. Just a bit stiffer, or equipped with a spacer which has the same length as the reduction of the piston travel.

 

Shorter springs don't make the motor use any more energy than it needs to, increasing ROF.

Umm... No. Unless you also let the muzzle velocity drop. The length of the spring does not matter, because it's pre-tensioned in the exact same gearbox. And the spring has to be long enough to positively hold the piston forward.

 

-Sale

[Tecro]

My mistake about the Systema springs then. Heh, they are progressive after all...thanks for pointing it out. Correct, I am greatly inexperienced, but I believe we're all speculating regarding the performance of shortened springs. So far, nobody except the airsmith mentioned in the first post has tested this and posted.

 

Also true is the fact that vented cylinders and long springs allow for extra power, but that's compared to an unvented cylinder. However, you can't escape the fact that vents are simply a workaround. Without them, air and energy is lost through the barrels. With them, you're still losing the air and (some of the) energy through the vents. They are not the most effective system, or we would all be using PSG-1 parts with vents. Trust the manufacturers, they know what they're doing.

 

But, I am not comparing vented cylinders to unvented cylinders. I am comparing the use of a vented cylinder and long spring to an unvented cylinder with a genuinely shorter spring. Have experiments been done comparing vented cylinders to unvented cylinders? I'd like to know the FPS drop. With this, the minor FPS drop is already combated by the use of a stronger spring, and you should theoretically still save energy because none of the air is wasted.

 

What you're suggesting about shorter springs makes no sense, unless you would also shorten the piston stroke for a shorter barrel, and use a stiffer spring to make up for the difference. But even then the spring wouldn't need to be any different than other AEG springs. Just a bit stiffer, or equipped with a spacer which has the same length as the reduction of the piston travel.

Which part doesn't make sense? The fact that a shorter spring is driving a long piston cycle? I'm not sure, but I don't think the piston would even move the entire length. No energy is used in moving the piston after the BB has left the barrel, simply because the spring stops short. That said, you would need to file down some of the teeth and put a stopper inside the cylinder to shorten the cycle. The compatibility issues I mentioned would definitely be fleshed out, but a bit of filing *should* settle that.