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git: https://git.xythobuz.de/thomas/OpenChrono
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github: https://github.com/xythobuz/OpenChrono
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date: 2022-06-26
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-update: 2022-07-01
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+update: 2022-07-07
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comments: true
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---
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@@ -146,6 +146,8 @@ lightgallery([
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Attaching the whole unit to a airsoft gun barrel turned out to be a bit tricky.
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+### M1911 Red-Gas Blowback (Part 1)
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The first gun I wanted to test with is a full-metal TM 1911 clone with a gas blowback system.
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The repetition imparts a big impulse on any barrel attachment, big enough to break my self-made silencer adapters in the past after a single-digit number of shots.
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Of course OpenChrono is much heavier than a plastic silencer imitation, so predictably it broke after only three test shots, even though I supported the weight with my hand.
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%-->
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+### M11 Co2 Non-Blowback
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For the second test run I tried to use a non-blowback ASG Ingram M11 Co2 gun.
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Besides some unrelated problems with the magazines it worked relatively well.
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Even without blowback the impulse on firing is still big enough to cut out the AA battery power.
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@@ -191,6 +195,8 @@ With the first shots with a fresh capsule the speed is about 105m/s, which is 1.
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The speed then reduces with each shot and goes back up again when waiting long enough between shots, as the capsule slowly heats up again.
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With the last couple of shots I took only 0.23J were left.
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+### M1911 Red-Gas Blowback (Part 2)
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After getting a metal threaded adapter from 14x1mm-CCW to 12x1mm-CW I was also able to continue testing with my 1911 blowback pistol.
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It worked fine!
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The printed female thread can withstand the forces much better.
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-The measured speed / energy seeme a bit low, that's because I was using a propane magazine with a Co2 hammer spring.
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+The measured speed / energy seeme a bit low.
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+I suspect that's because I was using a propane magazine with a Co2 slide spring.
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Another topic is the weight of the OpenChrono device.
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When attaching large weights to the front of a 1911-style mechanism, the force required to actuate the slide is much larger.
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Therefore the valve is open for a longer time, increasing the gas usage.
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So the magazine gas chamber empties quickly and, I suspect, the BB force is reduced as well.
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That's a drawback of this style of chronograph mounting for some guns.
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+### Tracer Unit
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+Unfortunately the tests with the UV LED tracer did not work out that well.
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+When dropping a BB through the device it actually visibly lights up as expected.
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+But the velocity is far lower in this case compared to a real shot.
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+When trying the same with either of my two guns the BB is not visible at all, even in complete darkness.
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+The power output of the two LEDs is simply not enough (`2 × 3V × 20mA = 120mW`).
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+[Experiments done by airsofttech.dk](http://airsofttech.dk/Guides.cshtml?Page=TracerUnit) suggest we need at least 20 times as much power, with ~3W going into the LEDs.
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+So for now I do **not** recommend to build OpenChrono with the tracer option as it currently can be found in the repository.
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## Build Guide
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<a class="anchor" name="build_guide"></a>
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Also take a look at [the "Hardware" section of the README.md](https://git.xythobuz.de/thomas/OpenChrono/src/branch/master/README.md#hardware).
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You can find detailed parts lists, schematic and wiring plan there as well.
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+### Parts
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Before starting the build you need to acquire the following parts.
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<!--%
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-For the UV tracer option you also need the following parts.
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+<s>For the UV tracer option you also need the following parts.</s>
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<!--%
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tableHelper([ "align-right", "align-right", "align-right monospaced", "align-left" ],
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[ "Description", "Type", "Count", "Link" ], [
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- [ "UV LED 3mm", "", "2x", "<a href=\"https://www.ebay.de/itm/373071970513\">eBay.de</a>" ],
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- [ "Resistor", "30Ω", "1x", "<a href=\"https://www.ebay.de/itm/372813822157?var=642490601725\">eBay.de</a>" ],
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+ [ "<s>UV LED 3mm</s>", "", "<s>2x</s>", "<s><a href=\"https://www.ebay.de/itm/373071970513\">eBay.de</a></s>" ],
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+ [ "<s>Resistor</s>", "<s>30Ω</s>", "<s>1x</s>", "<s><a href=\"https://www.ebay.de/itm/372813822157?var=642490601725\">eBay.de</a></s>" ],
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]
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)
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%-->
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-### Tracer Option
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+### <s>Tracer Option</s>
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-If you want to build the left half with the UV LED tracer option included I recommend using the existing ground connections of the IR LEDs and phototransistors.
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+<s>If you want to build the left half with the UV LED tracer option included I recommend using the existing ground connections of the IR LEDs and phototransistors.
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That way you only need to run two additional wires.
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-I placed the 30Ω resistor on the underside of the Arduino, shielding it with some heat-shrink tubing.
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+I placed the 30Ω resistor on the underside of the Arduino, shielding it with some heat-shrink tubing.</s>
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<!--%
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lightgallery([
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I'm sure it is also possible to make better use of the space inside the device and make wiring much easier that way.
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Also the tracer feature has been kind of an afterthought.
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-I have no real use for it and have not really tested it.
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-So I'm not sure how well it will work in practice under different conditions.
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+I have no real use for it and it does not work the way it currently is dimensioned.
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I also don't think it's realistic to take this bulky device onto a field, but who knows, I'm not really into that.
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To be quite honest, I'm happy with the device as it is now.
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-But I'm always open to feedback and pull requests of course 😉
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+But I'm always open to feedback and pull requests of course, especially ones improving the tracer option 😉
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## Potential Other Uses
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<a class="anchor" name="potential_other_uses"></a>
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