Sunday, September 29, 2013

Boring ballistics stuff. Chrono data, dart aging, RapidPistol, Z90 Redux.

Today I ran some more stuff over the clock.

First up: the Splatmaster Z90 got retested with Elites loaded all the way to the breech end of the barrel.

In the previous test of the Z90, all darts were loaded with the tip flush with the muzzle to produce a fair comparison with Sonics and Elites. I figured I would give it another go with Elites pushed back about 3/4" farther. Honestly, I didn't know what would happen to velocity and consistency, but I'm glad I tested that! It turns out that dead volume has a massive effect on these small-displacement springers and the 3/4" of pushback is worth 10-20 fps! Now we are pulling over 120fps with elites. Not shabby, and more in the same league as a good NF now.

Second, the RapidPistol got its test, finally.

Note a few things.

One, I have standardized the chrono data spreadsheet format, added some basic statistics (standard deviation, min/max and extreme spread) to make consistency and practical performance more apparent and foolproof than just the mean and the list of shots, and get more in line with how Foamdata Services and the like are reporting data. I also standardized the sample size for a normal test to 16 shots and will try to avoid throwing a random few rounds over the chrono and calling that a real test. It's not large enough for over the top statistical analysis, but it communicates quite well how the gun behaves and is enough certainty for what we are doing here.

Two, for flywheel guns, I have began recording the pack voltages at the beginning and end of each test. Fully charging the pack before a session does not remove the change in voltage during discharge, which is not negligible during a 100+ round chrono session, so this is better quantified in case some use or relation of that voltage data comes up that could call into question the integrity of the chrono data. Also, the energy consumption of a gun becomes apparent when the resting voltage of a Li-ion pack is monitored, and this will be useful as a rough estimate of battery life.

Three, new darts were tested against equivalents that have been in service for a decent time and would still be considered fit for use by my standards of the past. This was in response to this post by infamous and azrael at BNBS. While I have long known about significant negative effects on ballistic performance as darts age, accumulate normal wear and damage, lose the original foam dimensions and stiffness and gain defects, I honestly never knew how bad it was, and I have never bothered to test it. Infamous had posted some chrono numbers from a stock Retaliator that didn't seem to make sense, and I had commented something about that on reddit... but on further investigation they encountered a massive discrepancy in velocity between used and unfired darts.

Thus, I will be investigating foam degradation further. Here, I have completed the flywheel portion with this RapidPistol with shocking results - brand new darts, through flywheels, produce SIGNIFICANTLY more velocity than darts that have been mildly degraded and would still have been judged not just usable, but equivalent to new dart performance, in the past by visual and fit inspection!

Furthermore, I caught a flywheel-related wear mechanism that I don't think has ever been noticed before - when fired from some types of flywheel guns, the flywheel slip as the dart is grabbed results in wear of the foam near the front end of the dart behind the tip.

Such wear can eventually cause flat spots or a uniform reduction of diameter, visible as a "blunting" of the sharp cut edge of the foam, and this has a SERIOUS velocity effect. Several unexplainable low-velocity shots occurred which led to this finding (and were discarded after finding the anomalous darts, pending a test of exclusively worn darts culled from my dart supply to quantify the effect of this wear).

I also completed a "stockish" springer test with an AR'd Strongarm. There is a definite difference between new darts and used darts, even those that seem perfectly fine to any practical inspection! Seriously, if you are in some kind of competitive environment, ALWAYS RUN NEW DARTS! It's not a small edge you gain, it's massive. Trust me, I have the most stringent standards for darts during HvZ season of practically anyone and THAT is my baseline to which I compare new darts in these tests so if you simply cull worn-out darts YOU ARE NOT IMMUNE TO DART WEAR. ALWAYS USE BRAND NEW DARTS WHEN IT MATTERS! Also, these T-code Elites have uniformly had unreal performance. That warrants yet more testing. Perhaps code shopping is about to get reignited!

Still to come are a "pro stock" test with a heavily sprung Retal and Triad, and a test with pneumatic and spring guns with cylindrical barrels - convenient at the moment are my trusty SSPB attachment and my Z90 Splatmaster. In addition, I will be performing an aging test, involving the repeated firing and handling of said darts in a manner consistent with use, so as to create some kind of understanding of service life.

Saturday, September 28, 2013

90% WIP Rapidstrike Integration On Rapidstrike

Many members of the community have joked about this.

You know, "What's a good integration for a Rapidstrike? How about another Rapidstrike? Lol, not really."

"Put a Rapidstrike on your Rapidstrike so you can Rapidstrike while you Rapidstrike."

"Yo dawg, I heard you like Rapidstrikes..."

Except when I mentioned it, I wasn't kidding around.

Friday, September 20, 2013

Review and Chrono: JT Splatmaster Z90 Pistol

JT Splatmaster is a line of low-cost, .50 caliber spring-powered paintball markers that are very nerf-like in concept and parameters - and often directly nerf-ready without modding.

Such is the case with this Z90.

Thursday, September 12, 2013

[Review] Buzzbee Extreme Dart

As I discussed in my Shelf Watch post recently, Buzzbee has recently reworked the Air Blasters Extreme series somewhat, to include the separate availability of these darts.

This 18-round card pack was found at a Wal-Mart in Florida for $4.88. No cases or other quantity packages were found.

Go ahead, keep reading after the jump, I know you are there thinking about it.

Wednesday, September 11, 2013

Rapidstrike deserves an internal battery pack...

But not in the front of the damn thing.

I was messing with a spare RS stock left from the RapidPistol build, when it hit me: There's room in there for a stick pack!


Those two Panasonic NCR18650B have nothing to do with this project, they are just a stand-in for the 2S pack of Sanyo UR18650SAX that will eventually be put here once I get my latest order of cells and pack assembly materials.

There is room available in these stocks, with some hacking and grinding, to fit larger cells. I don't have any loose Sub-C cells to try but I would guess they would fit. A-diameter cells like 18650 lithiums and 2/3A NiMH will fit without a doubt no matter where the wires are placed on the pack. There are also probably some expensive, airsoft-specific LiPo packs that could be employed in this setup.

Speaking of airsoft, that is where the idea of a stick battery came from since a lot of very similar needs exist in airsoft (desire to hide a big and capable battery pack inside a realistic and tactical-looking weapon's original design and interior spaces...), so if you want your RS to be a bit cleaner, better balanced and integration-ready, you may want to look into airsoft suppliers of battery packs for use in this mod.

A 3S of 18650s may be a little tight, but it might actually work out as well. I am going to use this on a stock-motor RS build so I am using 2S.

Shelf Watch: Zing Products, Buzzbee, Rebelle at Walmart...

Welcome to the second episode of Shelf Watch, now a regular blog series!

Today's hunting grounds: Butler Plaza Wal-Mart, Gainesville, Florida

First up we have an electric soaker from Buzzbee.

Monday, September 9, 2013

RapidSwarm details.

And now for what's inside this thing. I will not cover the RS because that is the old Blade motor tester, but rather focus on the Swarmfire.

Swarmfire receiver to barrel shroud joint. A single layer of PVC sheet made from flattened 4" SDR 35 PVC sewer pipe was used to mate the two with the correct standoff distance.


[Mod] Swarmfire Reliability

Up now: how to set up a Swarmfire rotation system to handle high-rate full auto, worn parts and adverse conditions without skipping a beat.

Saturday, September 7, 2013

RapidSwarm and RapidPistol Completed


Ready to get a combat test. Rock solid.

Rifle and pistol. This is similar to an old image of mine with a Swarmpede and a Guardian PDW side by side. These RS are the successors of those Stampedes, so it makes sense.

Something that is not obvious is the Swarmfire trigger, the tiny orange button just under the flywheel cage of the RS, which is on top of a stock switch out of a Stampede or the like. A 203-style trigger pack was considered, but the bulk recommended against it. In the absence of suitable small switches and a MOSFET to set up an extremely compact trigger module, I used this support-hand button trigger concept taken from the MASS-1. It's not optimal but it stays out of the way and isn't way too easy to ND.

 Also fixed battery leads on the RapidPistol.

Close fit. Not compatible with barrel extensions, but why the hell would you need a twist-lock on the muzzle of an assault rifle? That is a RS feature that seems more like a gimmick than like modularity. I can understand the Spectre can, kinda. This doesn't need it though. Shorter is better in a zombie situation.

It's a terrible internals shot but I was up late working on this thing and wanted to get it done, so documentation of the process fell by the wayside and this is all I have. You can see the rear protrusion of the Swarmfire receiver which is as close to the flywheel cage as feasible and touching the front side of the magwell web, and that is after grinding some strategic areas.

When I put a better spring pack in the Swarmy, there will be images of how it disassembles. The Swarmfire is of course hung on the Rapidstrike barrel shroud, but what's more is that the RS flywheel cage has its two front screw bosses on the barrel shroud as well. By removing the 2 rear flywheel cage screws, the whole front assembly (flywheel cage, barrel shroud, Swarmfire) lifts out in one piece.

The battery wiring was rerouted. The harness now has the battery leads attached to the front assembly (connected to the Swarmfire trigger and motor) and a second Deans connector in the magwell that supplies power to the RS.

Thursday, September 5, 2013

WIP RapidSwarm

Just roughed in this primary.

This is the RS development mule, its life as the lab rat for electrical upgrades over and its tour of HvZ duty about to begin.

This is NOT a slap-it-on affair. When I get a shot of the internals on this build, you will see how I CRAMMED the Swarmfire in as tightly as possible with absolutely zero exceptions for anything! Keeping this integration high and tight to the rifle was a major priority, being that a poor underslung installation can totally destroy the ergonomics and balance of the whole gun. In the past, this was also a major difference in my Swarmpede builds versus many others that had the Swarmfire hung at least 1/2" lower and 1/2" farther forward (that is, if they were not flipped upside down, shelled and other nonsense) - but this makes those old pedes look sloppy.

Look at it this way, I shaved down webs and the burrs left by flush-cutting excess plastic off in order to gain that fraction more.

Compared to the Swarmpede, which is several generations old but still has never had an equal as a well-rounded and effective HvZ rifle.

Until now! Time to wire that Swarmy up!

WIP RapidPistol

After hearing a report from teek42 of an unbarreled RS not shooting wildly every which way, I went ahead with shortening the former stock motor test gun to a pistol.

This is the shortest possible configuration. All battery box remnants are gone. The carry handle was retained, as I do not like the loss of aim reference that occurs when it is removed (leaving a non-flat receiver surface if you cut in the obvious locations). Plus, I like carry handles.

2s pack on the side gets the job done. Still to do: reroute those battery leads which were left from the last front-wired configuration, and bodywork of course. Then paint? I am also going to be putting carbons in these motors and swapping in a better set of flies when I get the chance.

There were/are plans to add a N-Strike stock mount and a stub barrel with twist-lock muzzle fitting for modularity. That is going to need to be balanced with minimum length and bulk. I could easily go as modular as a Stryfe - a full-auto Stryfe... but then again, regular old rifle RS with fixed barrels and receiver-integral handguards/barrel supports do that better. I may just keep it as is, being that this is definitively a quick and dirty type of weapon, is never going to be anything proper and formal and clean, and it is SHOCKINGLY short in its current configuration.

This thing may be my new secondary for HvZ.

Tuesday, September 3, 2013

Interesting data point on "TrustFires"
According to BritNerf user Hammy:
I am now modifying a RS (commisson) and this one has 4 trustfires with solarbotic motors

I used my fluke multi metre to make the measurement.

When the 4 trust fires are not loaded, then they read 15.86V, however once the flywheels are spinning, this voltage drops to 6.5V. and the current flowing is 1.7A...

Whoa! That is a stupendous amount of voltage sag under a very minor load!

With the variability of Fire brands of cells and the fact that the rest of the system (including the cell holder, which is a VERY significant amount of resistance) was never described, this cannot be a useful numerical data point.

It's still a stark reminder of why these batteries and this practice are not a good idea, though. I will cover and explain the situation with 14500 cells in more detail in one of the upcoming battery guides, but suffice to say, they are a very poor choice, if you didn't already know.

The gist of it is that this type of Li-ion cell on its own, even in a best case (such as cells from the likes of Sanyo) is totally unsuitable for the uses people keep putting them to in nerf! This type of cell is designed for a 1C or 2C discharge rate - 1.6 amps at the very most - and even at that rate, the cells are sagging a good bit and heating up. Its internal resistance is far too high to perform anywhere REMOTELY near how a proper battery choice will on a mod - and it is also being abused quite severely. The quality problems of Fire cells and resistance of cell holders only compound that, perhaps significantly.

Carry on, and seriously, lay off the TrashFires!