Saturday, March 18, 2017

NERF Rapidstrike quasi-sci-fi NIR "compliant"

Ok so not quite so NIR compliant but getting closer.  This partially satisfies my goal of stands out a bit in the visible but is decently camo'ed in the NIR.  Top image is in the visible meant to look a little sci-fi 'ish with semi-camo colors for arid-urban.  Bottom the NIR view with an ACU camo and multicam hat on some grass, leaves, and dirt.  I was surprised the techno-patterns blend act as a decent shape breaking pattern.  If I didn't leave the large black sections this might work well.  I may try some dark blues or purples since those seem to be quite dark in the visible but can be fairly compliant in the NIR as seen in the previous post. These paints were just model paint, not duracoat.  Im not that rich by any stretch to put duracoat onto a nerf rifle.

Also if your interested in more the company hyperstealth appears to do great work in this realm. http://www.hyperstealth.com/c3/

Also here is an interesting paper on oxide nanoparticles and their NIR properties.
https://www.gns.cri.nz/static/pubs/2013/SR%202013-039.pdf
just beware some nanoparticles may be a health hazard prior to proper binding. 



I also put a small bit of paint onto a few sudden death ships that have been sitting on my desk forever screaming at me to start painting again.

Now the question, do I paint another nerf or move on to an airsoft rifle.

Tuesday, March 14, 2017

Sci-Fi SL8 concepts

After narrowing my colors down a bit based on visible camo, NIR camo value at 780nm,  NIR at 940 (or 980?nm  not sure what the diode was spec'ed for).   I set out the colors to see what might be interesting.  If you look closely some of the colors appear to change reflectance a bit as you shift from 780 to 940nm illumination.  Particularly of interest is how some of the blue, dark purple and dark red are fairly bright in the NIR.   Duller, grayer versions of these colors may work fairly well as visible camo or stand out visibly while being effective for camo in the NIR.



Then started playing around in a photoeditor with an sl8 and afg found online to get a feel for possible color and pattern combinations.   Do we want a bright sci-fi  that stands out or one that blends a bit or blends a lot.   Interestingly, done right most of these will stand out far less in NIR than in visible.   Think of it as flashy "high tech imposing government forces" in visible for the average joe observing to keep his distance, and then if they are actualy engaged in an operation at night the weapon blends more into the background ambient.






Friday, March 10, 2017

NIR Color theory... crude

Deciding this was an interesting line of inquiry I acquired a paint sample set from Duracoat.  Many people have taken NIR pictures of their camo clothing, uniform,  rifles, etc but, at least that I have found, none have bothered to dig into more than a couple colors or samples.

My goal is to have a nice camo scheme for airsoft rifles that are NIR compliant and either 1. good generic camo for his airsoft games or 2, awesome sci-fi colors for my tendency to paint things sci fi.   Think of it as stealth-camo.  In the normal visible spectrum it appears flashy sci-fi though non-reflective, but in NIR it is actually a decent NIR compliant camo.  To start I used his plate carrier and hats as a reference and laid the Duracoat samples over them.  I marked out the ones that appear too dark under NIR illumination and gave the names of the rest.  Im seriously considering a more scientific method of comparison... but that always costs money. 

One interesting thing that was unexpected was that some colors like some blues show up pretty light in NIR when in visible they appear much closer to black which usually eats NIR.  Another is Duracoat's "anodized" fascimily paint shows up pretty light.  I suspect they may actually use AlO2 micro or nanoparticles with dye (which is the coating on anodized aluminum) in their paint matrix.   I suspect suspending various polishing powders such as Aluminum, Cerium, Titanium Oxides will yield a visible translucent affect to allow visible observation of the color underneath with minimal visible scatter while the degree of coverage of the particles in the paint will push the NIR scatter rates up to make them appear lighter to the NIR observer.   Tests I did in an earlier post where I had a matrix of rattle cans had vertical lines of paint and horizontal lines of clear coats.  The clears did little to affect the NIR response and so I suspect a clear (such as Duracoat's matte clear finish) suspending an oxide would achieve the desired effect.



Saturday, March 4, 2017

NIR paint investigation

Some people take airsoft wayy to seriously.
A friend who I occasionally played airsoft with a few years ago started talking to me about a few night games he played a while back in which one team just dominated the field.  Apparently that had some night vision scopes and picked off anyone who dared show their face.  But apparently my friend said he and his buddies seemed to keep getting nailed more than others and he overheard one of them bragging about how some of the guys just glowed or stood out as dark blotches against a mid tone background.  Knowing my camera has a NIR pass filter I took it over to his place to see if I could help him ferret out the issue.  Looking at his uniforms made it very apparent what they were talking about.  Apparently his cheap kryptek nylon gear glowed like a beacon.  Anything just nylon glowed.  But is plate carrier and one set of ACU's did not.  we did a few paint tests with rattle cans and saw that standard camo colors ate NIR light like nothing else.

In the picture below you can see stripeson cardboard I painted as reference tests with the ACU uniform on grass, leaves, and concrete.  his GBB mags in his plate carrier were nice big black shoot me signs.  His Molle pockets made of cheap nylon (not shown) glowed like the sun under NIR illumination.  and aside from his higher end airsoft rifles which were anodized aluminum, the rest of his painted rifles were nearly black under NIR.   So he gave me one of his broken rifles and asked me to do some paint tests on it.  The first such paint test is in the bottom right.  This shows a tan rattle can paint seems to give decent matching to the ACU's.  And a black nerf gun just ate light. 

Colors are awesome, especially when you leave the visual spectrum.   I'm hoping I can convince him to cover costs so I can look more into NIR camo paints as I have a few ideas I want to try out.

Long story short,  Black rifles may look cool and scarry.  but they scream "shoot me" on the airsoft field if someone has night vision.  And don't buy those cheap nylon uniforms or pouches.


NERF Hailstorm: Rival Kryptek

Seeing videos of people converting their nerf rivals I had to give one a shot.  Since C and D batteries are so passe I first replaced its 6 C cells with 3 8000mah lithiums which allows this thing to spit out 12 rounds in well under a second.   I modified the trigger to be a two stage trigger pull half way to spin up the flywheels and a high power ducted fan for the feed tube, wait a quarter second then pull all the way to open the gate and unleash nerf hell.  When this bad boy spins up you know its time to duck and cover. The balls also dont feel very good when you get hit so WEAR SAFETY GOGGLES.

I havent spent enough time to work out the feed issues with the backpack. At present Im thinking some sort of cork screw to prevent clogs.  A project for later...

I decided to paint it with a kryptek style staying with light blue grays or silvers. Other than the backpack clogging issues, and that there is no reasonable way to play with others with this, I am quite proud of this bad boy.  Next I need to develop a filtered vacuum cleaner to pick up the hundreds of balls this baby can fire in a minute. 









Parents get sabers too!

It was unfair for the kids to get sabers so the wife and I get sabers now.
I have a light staff under way but at this rate itll be another 6 months.  Too many other projects.
She gets one that looks vaguely sith like with scratch marks for grip while I get two black and silver handled  more classical style.  Both handles are aluminum with a mild level of polish and the grip black is a duracoat for maximum durability.  


She got the bight teal on the top while I got an aqua and ice blue.  Hers is brighter because its a fixed LED while mine are RB and RGB. 

For the internals I used lightsaberos for arduino as found many places on the net.  Modifed the code a bit, and after a lot of playing figured out a stack which allows an arduinonano, a sound amp, an mp3 player, voltage regulator etc all on one board.   later I further added a 5V boost because on powerup with high power blades we often got a brownout on the boards causing a reboot or glitch state.  a buffered 5V boost allows the arduino to stay powered at 5V even while the batter takes a large initial hit.  

Further powering a few hundred milliamps up to an amp for the LED array takes a fair amount of fet power.  I milled aluminum heatsinks that socket some FETS and allow a set screw in the handle to press the heatsink into contact on the ID of the lightsaber aluminum tube turning the entire handle into ground and a heatsink.  Otherwise these fets overheat and blow within 30 seconds.  It turns out using red is even worse because it has such a low potential drop  compared to blue and green that the fet has to dump a ton of power.  Thus why people making red blades often run half of their LED's in series with the other half.  Blues have such a nice high voltage that the fets down have to dump much heat.  The quad fet below is powering an RGB saber. with two fo them running the Red led's.  The 6 fet sink runs the blade in segments with a common ground (or anode, I forget which) making the blade power up in sequence.