A guide to the Polarstar Fusion Engine

[Ike]

I happened to stumble across a post on Airsoft Mechanics from somebody who had some interesting results following my guide. He posts his entire set-up with chronograph results at the bottom.

Well, I guess I'll start this thread off in the right direction.

My setup is as follows:
PolarStar Fusion Engine (blue nozzle)
Classic Army Hop-up
R-Hopped 509mm Madbull Inner Barrel
Magpul 75rd P-Mag
Ninja 90ci/4500psi tank w/SLP regulator
Single stage air rig

So on to the settings and what-not.

After following a guide on the Michigan Airsoft forums I found what I believe are my settings. They should allow for adequet air volume, but still give me the highest rate of fire I am able to achieve at the respective PSI.

FCU Settings:
rE:21
dN:08
dP:20
rF:12
dr:15
cb:On
db:00

@80psi I recorded the following information:
.20 Matrix bbs - 388 fps @ 24 rps
.30 Matrix bbs - 358 fps
.40 WE bbs - 324 fps

@120psi I observed:
.20 Matrix bbs - 420 fps @ 24 rps
.30 Matrix bbs - 415 fps
.40 WE bbs - 380 fps

Source:
forums.airsoftmechanics.com/index.php/topic,7419.msg79225.html#msg79225

[Master_Oki_Akai]

This is good. I have been recording my own results as well.

[Gimpalong]

@80psi I recorded the following information:
.20 Matrix bbs - 388 fps @ 24 rps
.30 Matrix bbs - 358 fps
.40 WE bbs - 324 fps

.20s @ 388 fps = 1.39 joules
.30s @ 358 fps = 1.78 joules
.40s @ 324 fps = 1.94 joules

This is a perfect example of what we've been discussing as far as P* users "cheating" the chrono.

This user chronos under 400 fps with .20s, and so thinks he's good to go on the field. His energy output, when he switches to heavier weight bbs, exceeds the 1.5 joule maximum limit for AEGs firing fully automatic (.20s @ 400 FPS = 1.5 joules)

This is a rifle that shouldn't be allowed onto a field in MI if we're going by our current set of rules.

Granted, the rules where he plays might be different and his energy output might be fine by his field's standards.

[Master_Oki_Akai]

Honestly the joule limit never even occurred to me. I'd only paid attention to the fps rules. Now I know how I can make full use of the weight settings on my precision chrono.

[Ike]

By the current set of rules, I would say that that rifle is legal. Our rules are based on FPS, not joules.

Engagement limits are based on averaged fps readings using .20 gram weight bb’s only.

miairsoft.proboards.com/index.cgi?action=display&board=r-n-r&thread=6786&page=1#109994

[Gimpalong]

My understanding is the following:

FPS is essentially used as a proxy for joules.

400 FPS with .20s is 1.5 joules of energy. We wouldn't let someone shooting 430 FPS with .20s (>1.5 joules) onto the field, so why would we let someone shooting .40s at 324 FPS (1.94 joules) onto the field?

The amount of energy we're putting on target is the thing we have to pay attention to in addition to FPS.


Polarstar users consistently report that they experience far better range and accuracy when they adjust their poppet dwell setting to overvolumn their barrels using .20s, and fire >.20 bbs on the field.

These reports shouldn't be surprising. They are putting out more energy and thus reaching out further.

The problem is that many users are only paying attention to FPS, and neglecting the other side of the coin, energy (joules).

[Master_Oki_Akai]

Well that's full auto outside 20 feet. And since the P* can't technically count as a permanent semi-auto (even though you can tune it as such) then a P* unit would never be allowed to shoot over 400 fps with .2s or equivalent. Unless someone makes a sniper and gets special permission, but then what joule limit is that keyed to? 540-550 fps equates to about what?

[Gimpalong]

P* can't count as a permanent semi-auto only? I don't think that's how they've been being treated on most of the fields I've seen. Honestly, I don't think that there's been a ruling on whether or not P* with their FCUs set to semi-auto only (semi in the semi position on the selector, semi in the full auto position on the selector) count as semi auto only.

Obviously, a semi-automatic only P* DMR falls under different FPS/energy limits than a fully automatic P*.

Here's the calculator I've been using to figure out joules at different weights and FPS.

www.arniesairsoft.co.uk/?filnavn=/articles/fps_limits/fps_calc.htm

[Master_Oki_Akai]

Well I say technically can't because the FCU chip can be accessed and changed in the field in only a couple moves, very quickly and one can't really lock it down with a tournament lock. As opposed to changing the pressure valve which is easier unless it has a lock on it.

That's just me and what I can imagine people doing. Personally I'd like to see it count if you leave it on semi auto and we all play honest but I also know you can get the trigger response to be really quick.

Well according to the calculator (thanks for that btw) at 500fps with .2s it's firing at 2.31 joules, 2.89 with .25s so we'd be getting into the range of doubling the joules when using heavier rounds which I think is a typical practice for snipers and DMRs.

So alright we acknowledge 1.5 joules as the limit for full auto fire and say 2.0 or 2.5 joules for single shot which sounds fair to me. Anything hotter than that doesn't have a place on the field except as a special item or event like a super duper bolt only sniper or a mounted turret.

[Knief]

Ike,

Gimpalong is entirely correct in his assessment of FPS rules and how they relate to energy. We've always used FPS recorded with a known weight bb as a proxy for energy because there's no efficient way to chrono everybody with the bb weight they'll use on the field and run calculations off of that. Before the P* hit the market, that wasn't a concern because no other gun saw a significant increase in muzzle energy as bb weight increased (we know it happens, but it's a slight creep, not a 33% jump, which is massive in terms of muzzle energy). With the numbers on the tuning above, that "field legal gun" is hitting the same muzzle energy as a normal AEG shooting .20g bbs at almot 460 FPS. That's way too hot.

Now that we see guns capable of making this jump in muzzle energy, we might have to amend the rules to specifically state that these FPS measurements are a proxy for energy and that you're responsible for keeping your gun under that energy limit regardless of what bb weight you use. I could see that being important for a new player who doesn't have a concept of how FPS and bb weight relate to muzzle energy and player safety. What I'm surprised by is that you don't seem to understand that concept. Or rather, you're choosing to ignore the obvious intent of the rule (which I know you know) to pull some, "well, technically..." bullshit. I'm a little disappointed.

Oki-Akai,

The Energy limit for a semi-auto capable rifle is 2.8J. You can set up an equation in Excel to calculate and do all of the calculations and unit conversions (I can post it up if you're interested), but you can also do quick calculations here:

arniesairsoft.co.uk/?filnavn=/articles/fps_limits/fps_calc.htm

Or, you can reference my handy-as-fuck chart which lists MiA FPS limit, the equivalent Joule limit, and the corresponding FPS for common bb weights:



I also have a full chart with every bb weight I could find up to .50g and energy limits at 300, 328 (1J), 400, 410, 450, 500, 550, and 600 FPS in spreadsheet form. If anybody is interested, I could send it their way.

As for P*s and their semi-auto capability, I just told somebody that if all he has is the FCU switch, then it's not semi-auto only. That's far too easy to adjust. Frankly, P*s are a pain in the ass for even hosts and a lot of people who don't use them don't like to play against them either (because of people cheating the chrono with Ike's mentality). I'm not inclined to cut P*s a lot of slack on the rules.

[Master_Oki_Akai]

There we go! Thank you for the confirmation. Just what i was looking for.
So for the sake of short hand : 1.1-350, 1.5-400, 2.5J-550fps with 10fps of wiggle room.

But one more time, just for the record please. For the sake of physical safety and simple chronos not withstanding, we are caring more about the muzzle energy more than the actual fps here right?

Like if I wanted to be a knucklehead and put .12s in my unit at Long Range (2.81J) and shoot at 700+ fps just as a goof. I wouldn't, but just as an example to determine priority.

[Ike]

Fair enough, and understandable for the velocity to be considered a proxy for joules.

Oct 27, 2012 16:51:18 GMT -5 Knief said:

As for P*s and their semi-auto capability, I just told somebody that if all he has is the FCU switch, then it's not semi-auto only. That's far too easy to adjust. Frankly, P*s are a pain in the ass for even hosts and a lot of people who don't use them don't like to play against them either (because of people cheating the chrono with Ike's mentality). I'm not inclined to cut P*s a lot of slack on the rules.

What do you suggest a Polarstar user does to his rifle to make it semiautomatic only then? As a follow up question, almost like we're merging two threads here, what do you have PTW owners who wish to use a high powered cylinder do to ensure that their rifles are permanently semi-automatic?

[Zorak]

One approach has been to drill threads in the body just forward of the semi position and insert a screw blocking the switch from moving past semi. Of course that can be reversed with tools, but we assume people won't need about with tools in the field.

[Master_Oki_Akai]

That wouldn't work. As long as the user can access the FCU they can flip the Semi/Full Auto selector positions.
On a standard AEG yeah, i can see that working, but not a P*
That's why i said it technically can't be considered as such.
I'm afraid that as of now there's really nothing that can be done about it except for field owners to allow or deny their use at events based on trust or reputation.

[Gimpalong]

I've already mentioned the regulator locks, but there are also FCU locks available.

See here: www.shapeways.com/model/647239/hinged-tournament-lock-to-fit-polarstar-s-fcu.html

and

here: www.shapeways.com/model/647260/tournament-lock-protector-sleeve-for-p-fcu.html



Honestly, I think it's a bit much to require P* users to have both reg AND FCU locks. At some point we've got to start trusting people and policing them accordingly. If you're using a P* on the field you should start to expect a certain level of scrutiny until you can prove that you're a responsible user.

Someone shooting a semi-auto only P* DMR is going have to 1) demonstrate that their rifle truly is semi-auto only at the chrono station and 2) be tagged with an appropriate colored zip-tie. If they've got a 100 ft MED zip-tie then, obviously, they shouldn't be shooting fully automatic. If an even host or anyone else were to spot this on the field then you'd think someone would step in and say something.