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#353908 Post your DIY/Maker/Craft/Mod hobbies

Posted by Doom on 02 June 2016 - 08:09 AM in Off Topic

That looks amazing.  Could you do a DIY guide?

 

Both of my links are to guides.




#353895 Post your DIY/Maker/Craft/Mod hobbies

Posted by Doom on 01 June 2016 - 11:01 PM in Off Topic

shmmee, quite nice work. I bet the hair was heavy!

Back in the day I used to build homemade water guns. I've gotten back into this lately, though the new one I built this year hasn't worked so well and I intend to re-purpose it. I'm planning another one which would completely avoid the faults of my newest one.

One homemade water gun I built that I'm particularly proud of I called SuperCPS.

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This one worked nicely, but I broke part of it by trying to upgrade it. I never bothered to fix it, though I might now.

My most powerful one I called Supercannon II. Not practical for actual water fighting in any way, but it's extremely powerful and gives a good buck when shot, especially when the nozzle is removed so you have a 1.5" diameter water jet.

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#353821 Constant Force spring blaster infodump

Posted by Doom on 28 May 2016 - 10:43 PM in Homemades

Nice work.

 

Back in 2008 or so I bought some hefty constant force springs (probably 9293K14) for a water gun design. You usually want constant pressure, so this would do that. I don't remember all the details, but after getting two of the springs (to avoid the balance issue you have) I scrapped the project and returned the springs to McMaster-Carr. I think I decided the springs were way too unwieldy, and I was skeptical of the safety of the design. But this is making me reconsider given that it could be combined with another crazy idea I have for a water gun, which probably wouldn't require the largest springs.

 

Ultimately, I think Kane is right and increasing force is better for Nerf. You want to build up pressure as quickly as possible, so you'd want higher force initially to get higher acceleration and more compression initially.




#352981 Hobbyking Silicon Rubber Tubing

Posted by Doom on 23 April 2016 - 12:00 PM in Homemades

The age of the tubing is less of a concern than how many stress cycles it has been through. Silicone (silicon tubing does not exist to my knowledge and seems to be a typo on Hobby King) rubber can be pretty good in this regard from what I've read, but I've never seen comparisons with latex rubber. No time to look right now, but I'll post again if I find anything along those lines in the future.




#352016 What to do about Broken Images. Also, Fuck Imageshack

Posted by Doom on 05 March 2016 - 03:33 PM in Site Feedback

Langley, I did an image backup in 2014, and it appears to be on the root of the NH server in a file called "nh_images.zip". Probably is worth checking out for images lost in the interim. I don't have the time to look at it right now, unfortunately. I also don't recall saving the images in a particularly logical format. I imagine they were all just put in one directory, and if I wanted a broken image I'd match the filename. There could have been conflicts.




#350610 AR or venturi

Posted by Doom on 08 January 2016 - 08:14 PM in Modifications

Compressibility is a bitch. Just like a sponge can be squished and change it's density, so can a fluid, and all these easy equations go out the window. For a fluid to reach the point of compressibility, the air flowing in the pipe must be greater than 0.3. If the barrel is plugged by a dart, logically, the air flow cannot exceed the speed of the dart. In something like a suped up 4B, the FPS can reach 300 if you plug the pump, it's more like 250 for high end springers. So with the speed of sound at sea level being 1125 FPS, the mach number of a springer's barrel would be 0.22 and for a 4B, more like 0.27, so we get pretty close to compressibility being an issue, but dodged that bullet for now, so that above equation is valid. Honestly in some of these looser fit 4Bs I wouldn't be surprised if, when hooked up to the right equipment, we actually got into the realm of compressibility.

BUT if that restriction is made too small you begin to run into the problem of compressibility in homemades. For Nerf brand shit you won't have to worry about that.


(This is somewhat technical and can be ignored by most people.)

The phrase "compressibility" is used in several different senses in thermal-fluid science, and they can be confusing. The Mach number does not need to go above 0.3 (or whatever cut-off is set) to have compressibility effects. Take a sealed piston, compress the gas, and hold it still. The Mach number is zero, yet there's a change in density.

The Mach number is about the speed of sound. You can have a flow where the velocities are well below the speed of sound, yet density changes are important. Buoyancy driven flows (e.g., from combustion) are one major example. I work in fire protection, and the variable density low-Mach Navier-Stokes equations are the starting point. Nerf is another example. The density changes are appreciable, but you generally don't need to worry about the speed of sound effects. So that equation is not applicable.

This is not to say that Mach number effects are not important in Nerf guns. The flow could easily choke in restrictions. In my old Nerf gun simulators, that was the only place I took into account Mach number effects.

To get back to the original question, I can't comment on the effect of this on performance. Seems situation dependent to me. It could act to reduce deadspace as Aeromech points out, or it could just restrict the flow. I'm skeptical of the "Venturi effect" explanation, as it doesn't matter if the velocity near the projectile is fast; the no-slip condition says the fluid will be going the speed of the projectile at its surface. So if the projectile is still, the gas will slow down, etc. It's often more correct to think in terms of pressure. Would this increase the pressure behind the projectile? Probably not, though this isn't the entire story. There's one way to know. Agles, if you think this has promise, test it out and let us know here.




#349293 Survey to help make better homemade water guns

Posted by Doom on 24 October 2015 - 01:41 PM in Off Topic

https://docs.google....DAVtMw/viewform

As some of you all are aware, I also run a water gun website known for homemade designs. We're running a survey to get a better idea of what sorts of tools people have, what sort of water guns they want to build, what sort of parts they can buy, etc., so that we can make better designs and build guides. Please take the survey if you have the opportunity.



#346940 Accuracy mods

Posted by Doom on 26 May 2015 - 10:00 AM in Modifications

Several years ago I wrote an article on a few possible ways to improve accuracy and precision. Some of these ways were mention here already, but check out my article if you want more.

Putting fishing line in your blasters barrel is common in Singapore its supposed to act like a "rifled" barrel


There's no evidence such a thing works. It's purely subjective, and a placebo effect at best.



#345640 Welcome to Nerf Engineering

Posted by Doom on 18 March 2015 - 02:14 PM in Darts and Barrels

This feature of NerfHaven is on indefinite hold. I do not have time to contribute.

I have not heard of internal fletching and can not find anything on the subject in a quick Google search. Let me know when you find something from the episode of the show you are talking about. I'll take a closer look if I have the time.



#343751 Engineering Stack Exchange

Posted by Doom on 29 December 2014 - 01:01 PM in Off Topic

Beaver, thanks for committing.

DartSlinger, thanks for committing and recommending the site. I can see there's been a jump in signups, so looks like things are working.

Anyone else who might use the site, please commit if you are able to. We're getting pretty close to completion.



#343746 chronographing for a nerf war

Posted by Doom on 28 December 2014 - 03:12 PM in Off Topic

I have some incomplete notes on dart safety here: http://btrettel.nerf...-incomplete.pdf

Hasbro uses a factor called KED to measure safety. In this article I detail KED limits for a variety of different injuries like bruising and corneal abrasion. You'll need a chronograph and a small scale to calculate KED. If you mandate using a certain type of darts, then you won't need a scale as long as you know the dart mass. Just convert the muzzle velocity to KED and you're good.

My recommendation would be to mandate use of safety eyewear. I won't make a particular KED limit recommendation, however. It's up to you to determine what level of risk is appropriate. You can look at my document to see how likely certain injuries are if direct impact is made.



#343705 Engineering Stack Exchange

Posted by Doom on 24 December 2014 - 10:05 AM in Off Topic

There's a proposal for an Engineering Stack Exchange website. I'm a big fan of Q&A websites in general, and I'd really like to see this get off the ground. There are quite a few engineers on this site. If anyone reading this could commit to using the site, I would be very appreciative.



#341119 How do i become an moderator or ambassador?

Posted by Doom on 09 August 2014 - 04:27 PM in Off Topic

Rule of thumb: If you ask to be a moderator or admin, you probably aren't going to become one.

At most forums I've been a part of, there are people who want to become moderators or administrators. Generally, this becomes at best a joke to those running the show, at worst a nuisance. Neither are good.

Also, you should seriously consider whether you want to become a moderator or administrator. The experience is often negative. Cleaning up the mess some members leave is not fun or easy. I also wasted a lot of time with forum politics when I was an administrator at my old water gun forum. Thankfully there is not so much forum politics in the NIC, or at least I've learned to ignore it by now.



#338323 What Happened to NerfRev?

Posted by Doom on 19 April 2014 - 07:58 PM in General Nerf

I've asked around about this. No one knows what happened.



#338277 Stock dart diameters

Posted by Doom on 17 April 2014 - 07:51 PM in Darts and Barrels

This might be old news, maybe not, but we have this thread on different stock darts from the HvZ forum. Might be useful to be using darts from the same production run.


Didn't notice this reply. I did look through that thread before, but I don't think the subject has been discussed on NH before. Thanks for bringing this to our attention. Given torukmakto4's findings, I'd suggest anyone who posts stock dart diameters, masses, etc., also posts the tip code.



#338115 Chicago Nerf War?

Posted by Doom on 07 April 2014 - 10:36 PM in Nerf Wars

Apologies, rechecking my link and doing some copy pasta research I have determined it is impossible to link to an advanced member search. Thus the 'guide' to navigation makes more sense.


It's not impossible. You have to reverse engineer how the members list works. Try this link. Looks like for the location, you just add &field_6=location to the end of the URL.



#338070 Stock dart diameters

Posted by Doom on 06 April 2014 - 10:01 AM in Darts and Barrels

Birch, DartSlinger, thanks for taking these measurements. They'll prove very useful in my upcoming article.



#338049 Stock dart diameters

Posted by Doom on 05 April 2014 - 09:29 AM in Darts and Barrels

Lately I've been compiling data about darts. One thing I've found to be lacking is the available data about stock dart diameters. There basically is none, and for the moment I have no access to Nerf guns or darts to make my own measurements. Would someone with calipers mind measuring the diameter of the heads of their stock darts? Post that along with the dart type. Foam diameter and other dimensions would be interesting too, but I'm most interested in the head diameter. This'll be useful for an upcoming dart safety article, and I'll be appreciative otherwise.

To be more specific, if you look at whistlers, for example, you'll see that the head is bigger than the foam. For streamlines, the opposite is true; the minimum diameter of the head is smaller than the foam. This is the diameter I'm most interested in.



#337927 Why do slug darts need to be made with washers?

Posted by Doom on 31 March 2014 - 04:25 PM in Darts and Barrels

I always thought this was one of the main reasons for using washers over bbs/bearings/fishing weights - the washers have more surface area and are less likely to punch through the padding on the dart.


This is quite a correct point and I should revise my earlier statement because of it.

Has anyone done any dart durability tests? I'm thinking about shooting darts at a set velocity and a set distance at a certain hard target, say brick. I'd like to see some more specific numbers about how often weights break off, etc. I have seen that phenomena in wars, but only after looking at darts on the ground.



#337873 Welcome to Nerf Engineering

Posted by Doom on 30 March 2014 - 10:38 AM in Darts and Barrels

Nice post, RedFear. I was about to suggest posting your own thread, but seems you already have. I'd suggest changing your post to a link to that thread rather than updating both, as it's easier.

Also, as a note, if someone suggests that I investigate something and I'm slow, I'd be perfectly happy for someone else to jump in. I already have a lot on my plate.

Edit: So, I am being slow in general due to other obligations. I'm aiming for one new blog post a month now, and I'll mostly be working through my backlog. Feel free to post here with suggestions, still, as I'll take a look and others might be able to help as well.



#337844 Why do slug darts need to be made with washers?

Posted by Doom on 29 March 2014 - 04:55 PM in Darts and Barrels

Yeah, I always thought that Kane and the like were just being ridicules with all of their "safe dart" concepts. He was making a non-proven dart to solve a non-existent problem.


I wouldn't say that dart safety is a non-existent problem. The issue is that most common "solutions" are too restrictive in some cases and not restrictive enough in others.

I don't recall Kane saying anything unreasonable, though I don't think his metal-free (or more generally, hard-stuff-free) dart concept is necessary. Avoiding hard things is laudable, however. I don't think it'll happen without changes in how darts are manufactured, but incidentally, I bet Kane believes the same as he's working on automated dart making machines.



#337839 Why do slug darts need to be made with washers?

Posted by Doom on 29 March 2014 - 01:27 PM in Darts and Barrels

Given similar weights, there is no scientific reason to not allow ball bearings but to allow washers. Many dart safety practices are voodoo, unfortunately, so they don't make sense. These practices are based on unverified ideas about what is safest, not realities about what is safest. I suggest bringing this up with local war organizers if you find it is an issue.



#337791 Welcome to Nerf Engineering

Posted by Doom on 28 March 2014 - 09:51 AM in Darts and Barrels

Doom,
In your opinion, what is more important when trying to hopper an airgun, volume or pressure?


This depends on what you mean by "important". According to my theory, whatever configuration (pressure and volume) that gets you the right muzzle velocity will work.

With that being said, high pressures tend to have higher energy efficiencies, so I would bias my own designs towards that. Of course, there are other practical concerns (material strength and difficulty of pumping) that limit pressure.

Also, it's worth noting that my theory hasn't been tested experimentally. It fits the high speed video, sure, but I'd like to see more evidence.

If you want some starting points, there are some numbers in this thread, e.g.:

The only data I could find was CaptainSlug's Pepe, where he used a 10 psi 7 ci tank with a hopper.


Split at NerfHaven told me he couldn't get a hopper to work with a "small" 4 in^3 firing chamber.




#337773 Welcome to Nerf Engineering

Posted by Doom on 27 March 2014 - 09:58 PM in Darts and Barrels

I'm a little out of my depth here, but it would seem to me that double shots (two darts chambering from a hopper per shot) could be caused by too much airflow after the dart leaves the barrel. This may be fixed by lengthening the barrel.


I thought about double shots and didn't have a clear idea of the cause, but way too much air flow does seem highly plausible. Lengthening the barrel might help, but I'm not entirely sure as the only math I have for that is scaling. I'll have to think about it.

Also, I neglected to mention that my theory is based on the Venturi effect, which was previously hypothesized to explain how hoppers work. This idea combined with the high speed video in the thread were essential in figuring out what's going on. I did the math and found that the pressure drop from the Venturi effect is so small that darts can't advance unless the barrel gas flows into the surrounding air. This seems to fit with the high speed video. The darts don't advance until the current dart is out of the barrel and the barrel gas has had some time to drop to atmospheric.

I'll see if I have time to make a more detailed post about these findings this coming weekend.



#337770 Question about airgun fittings

Posted by Doom on 27 March 2014 - 09:46 PM in General Nerf

A few Nerfers have used barbed fittings. I imagine the reason they are rare is that Captain Slug used them because he liked them, and other people just copied what he did without thinking much about it. There are no disadvantages to barbed fittings aside from that they can be a little difficult to set up. You usually need tubing clamps to keep the tubing on. I'm not sure what the outer diameter of your tubing is, but something like 5324K51 should serve you well.



#337757 Welcome to Nerf Engineering

Posted by Doom on 27 March 2014 - 07:23 PM in Darts and Barrels

I'd make a small tank, and then a tank an order of magnitude larger, and another 2 orders larger. Maintain vent hole size with each. Test each at various pressures with the same hopper and barrel system, with a fake barrel that's only a few inches long, in order to demonstrate chambering. Sound about right?


That's a great start. I'd also like to consider the effect of dart mass (to isolate how much gravity helps), barrel length, dead space, dart head shape, number of darts in hopper, possibly the effect of some of the changes people have made to the feed path, and possibly firing angle (right side up, upside down, sideways). That's a lot of variables, so I'd like to get some idea about which are important.

Given that, I made a simple mathematical model of a hopper. I'll detail this in another post. It helped clear up what the likely important parameters are in my mind. To summarize, it seems that one of the major issues with hoppers is the muzzle velocity. I hypothesize that there's a muzzle velocity below which hoppers won't work. Let's call this the "critical hopper velocity" to sound scientific. This muzzle velocity seems to be controlled by the details of the hopper and darts, so it's not a universal constant. But, perhaps it's similar for most hoppers.

So, if I were to do some tests, I'd start with an airgun and a chrono. Barrel, chamber volume, number of darts in the hopper, etc. are constant between tests. The pressure is varied to change the muzzle velocity. If my hypothesis is true, at "low" pressures hoppers won't work, at pressures near the critical value the hopper will work about half the time, and at "high" pressures the hopper will work reliably.

Now, as for the question of what pressure and volume will get your gun to that velocity, that's where a computer simulator like GGDT comes in. Or, alternatively, experiments and past experience.

One of the other issues is muzzle blast, that is, blowing air out of the barrel after the dart has left. I hypothesize that hoppers require muzzle blast to work. The muzzle blast is likely what advances the hopper. This means that your barrels must be shorter than the ideal barrel length to use a hopper, which reduces the muzzle velocity. Muzzle blast in combination with the added dead space probably account for most of the energy loss associated with hopper use. Experiments and simulators can help you design a gun with a certain amount of muzzle blast. (I'm not sure how long a duration is necessary, though I'll do the analysis for it and compare that against the high speed video I have. First step is to figure out the frame rate of the video.)



#337681 Welcome to Nerf Engineering

Posted by Doom on 25 March 2014 - 04:25 PM in Darts and Barrels

I have no idea how many variables would need to be accounted for in order to solve for barrel length, but it seems logical to say that the best barrel length would be found where the acceleration of the dart equals zero. This would correlate with the maximum muzzle velocity of the dart. If there was a way to track the position of the dart inside of the barrel, it would be easy enough to make a function from that data, find the second derivative of that function and solve for y=0.

I'm not entirely sure if any of this is exactly practical, or if it is the best way to solve this problem. I would love to hear what you think about the subject, and hopefully the community will eventually find a use for the fruits of this labor.


Yes, maximum velocity is the criteria. You can read the internal ballistics section of my old notes for two ways I estimate this theoretically. The problem with theory here is that the equations can't be solved exactly in the most general case, so you are limited to simplified cases. You can get around that by using computer simulation techniques, but in that case it's harder to understand precisely what controls what. The theory helps you understand why and the computer simulation is more practical. Indeed, spud gunners use GGDT all the time to find ideal barrel lengths.

I don't know anyone in the Nerf or spud gun communities who have posted any useful data about experimentally finding the ideal barrel length. The easiest way to test this is to start with a barrel that's too long, shoot the gun while measuring its muzzle velocity (multiple times, because there'll be variability), and cut the barrel down in increments. Repeat this until you have an idea of what length works best. Despite the fact that this method has been suggested many times, I am unaware of anyone trying it.

An interesting alternative is to use a magnetic projectile and put coils on the barrel. From that you can back out the velocity at different points in the barrel and minimize the number of tests you need to do, because you can do one test with a long barrel. (The actual ideal length will vary a bit from what you'll find in this technique due to the flow being constrained by the long barrel, but this is really only important when you Mach number is high. I hope no one has that issue in Nerf.)

I know you already have your plate pretty full, but could you possibly make an article(or two) detailing the pressure and/or air volume required to hopper an airgun?


This was part of the plan. The problem is that we don't really have any good test data for this. Someone with more time on their hands could easily beat me to it. I could detail how I'd test this if anyone wanted to do it.



#337653 Welcome to Nerf Engineering

Posted by Doom on 24 March 2014 - 10:18 PM in Darts and Barrels

I would say that coefficients of friction for various brands of FBR on various brands of CPVC would be a good idea, but there is probably far too much inconsistency for useable data to be accumulated. Perhaps some common match ups could be outlined if a universal barrel length formula is ever created.


Friction measurements are one thing we seriously lack. The problem in Nerf is actually worse than you might imagine. The friction force is a function of the coefficient of friction and the normal force. Neither is known. Roughly, what we do know is that tighter barrels will have higher normal force and that some materials have less friction than others.

I recall discussing some ways to estimate the friction force with Split a while back. He used the bulk modulus to estimate the normal force. I suggested something more complicated that probably would not be much more accurate than his approach. I should look more closely into this.

Spud gunners use a simulator called GGDT which allows you to specify the total friction pressure, which I call the pressure of friction. This is basically the total friction force divided by the surface area. It represents how high the pressure needs to rise for the projectile to move and In GGDT, static and dynamic friction are equal, which is not realistic or necessary, so I don't make this simplification. I stole this notation for my own work.

If you can blow a dart down a barrel, you can be sure that the static pressure of friction is lower than the maximum pressure your lungs can generate, which seems to be about 0.9 to 1.4 psi for men.

As for ideal barrel length, I'll make a thread detailing two simplified theories I developed, how to measure this experimentally, and how to estimate this via a computer simulator. My simplified theories give very approximate equations which can be useful to get a rough estimate of the actual ideal barrel length and understand the basic factors involved in ideal barrel length.



#337585 Joint youtube channel

Posted by Doom on 22 March 2014 - 12:53 PM in General Nerf

Interesting idea. I have some plans to make a NerfHaven YouTube channel for war footage, but no plans for YouTube beyond that. The administrators and moderators here at NerfHaven are already somewhat overextended, and they probably would not be able to do much more than upload a war video every once in a while.

With that being said, I think a group channel would be a good idea, and I encourage other Nerfers to collaborate like that.



#337554 Welcome to Nerf Engineering

Posted by Doom on 19 March 2014 - 05:50 PM in Darts and Barrels

Hmmm. I was writing a ballistics program to calculate ranges at different angles and such. If I had a decent value on the drag coefficient of various NERF darts I could make a few tables/graphs for reference.


Sounds nice. In the post directly prior to yours, I linked to an earlier blog post of mine where I summarized the available drag data: http://btrettel.nerf...com/archives/78

Based on tests done by Daniel Beaver and koree, I would suggest using a value of 0.67 for the drag coefficient. This value fits my flat-fire (small angle) approximate theory very well and is in concordance with wind tunnel tests done for circular cylinders with flat and smooth noses.

You can read more about the flat-fire theory in my old notes: http://trettel.org/p...stics-notes.pdf



#337487 Be on the lookout for broken pages

Posted by Doom on 13 March 2014 - 02:39 PM in Site Feedback

I've made a few security changes to the site that might break some pages, mainly on the wiki. Post here if you notice anything out of the ordinary anywhere on NerfHaven.



#337323 Welcome to Nerf Engineering

Posted by Doom on 26 February 2014 - 11:35 PM in Darts and Barrels

Are you going to be taking attendance, do we need to print out a copy of the syllabus, and when is the first exam?


I find this to be amusing.

Looking forward to the Flywheel lecture.


I'd like to second the request for a flywheel post. There's little to no knowledge in the community as to how variables like wheel mass, moment of inertia, and motor torque affect performance. If we could get a Real Life Physicist to teach us the basics it could really help people who want to build their own.


I know little to nothing about flywheels, but they certainly are within my skillset. I'll take a closer look. Feel free to post some more information here if there's anything in particular that you find interesting (like, for example, someone else's thoughts about flywheels) or other particular questions you might have about flywheels.

I would recommend lecturing about shady ass generic Chinese valves. They are fairly difficult to come across any factual information about them.


Valves in general have a lot of issues. I'll take a closer look at this. I do know the Asian valves tend to use a different test method than the American ones, which adds to the confusion when you do have some information.

If you haven't, calculate the approximate drag force of a micro dart in terms of velocity (in ft/s for use with chronographs) and mass (in grams).

This way, we can use the drag force and gravity to create another formula to get an approximate range from Chronograph readings. This would only work for accurate darts, though. So not for streamlines.


All this has basically been done, though it's not well organized. See this old blog post about drag for the drag coefficient of a Nerf dart and similar shapes and my old ballistics notes for some equations to estimate range. One of my plans is to take that earlier blog post and some appropriate sections of my notes and expand on them in a larger post. I'd like to make an online calculator for range, too.



#337287 Welcome to Nerf Engineering

Posted by Doom on 25 February 2014 - 09:57 PM in Darts and Barrels

btrettel's Nerf blog was my blog about engineering Nerf guns. There I discussed various aspects of Nerf gun design with a particular focus on theoretical and experimental analysis. The goal was better Nerf guns.

Now it's a column titled Nerf Engineering in the articles section here at NerfHaven. The focus and goal are the same, but the audience is much larger. Despite that, I will make no attempt to dumb down the content. I write for someone in college or older. Some background in calculus will be required for some posts.

Expect a post every week or two. I have a large backlog of topics I've already analyzed, but have not written about in usable form. You can post requests here, in this thread, for now.

All posts here will potentially be updated after their original posting. The date of last update will be listed at the bottom of the post.



#337216 Nerfhaven hacked?

Posted by Doom on 23 February 2014 - 11:35 AM in Site Feedback

The email spam I started getting yesterday makes it a possibility that someone may have been able to steal the NH database of user email addresses.


Although the specific email I examined actually came from a compromised host in the Netherlands, it claims to have been sent by Noodleownz, and other vaguely familiar names appeared on "To" addresses. The spammers had to get it either from the site or from another member, because I created an email address just for NH. It's probably even slightly more likely that some member who has exchanged email with me in the past was hacked, there are so many 0-day hacks for windows browsers now.

I'm willing to share the list of addresses and associated names but only with a site admin, if anyone cares to bother checking the database. If the addresses were to all match NH members, then the probability the addresses were hacked from here would be higher. I wouldn't even suggest it should be any priority, though. Spammers eventually get everything.

Regardless, I recommend everyone change your NH password.
And if you were ever fool enough to use the same password anywhere else, change those too, and make each one unique this time.


Please forward the email and anything else relevant to me ASAP. My email is ben.trettel at gmail.

We have known about the hacking issue since it started, but so far we have not really done anything about it because it seems the hacker could regain access without much difficulty. The plan is to restore a filesystem backup from before the hack, upgrade the forums, and then continue from there. I'll see what I can do to annoy the hacker, though.



#336536 Abilene, Texas Area Nerfers

Posted by Doom on 18 January 2014 - 12:08 PM in Nerf Wars

That looks like a fun time. Thanks for posting about your war, redDKtie. Feel free to make a thread including the details for those who don't have a Facebook account. I may be able to make that, but it will be difficult given my schedule and lack of a car. If you know anyone coming up from central Austin, let me know.



#336486 Abilene, Texas Area Nerfers

Posted by Doom on 14 January 2014 - 07:13 PM in Nerf Wars

Hey, Also a newbie to Nerfing, and in the Austin area (about 3 hours away)

I've got a small group here and would be willing to drive if you got something good organized.


I'm also in Austin and would be interested in a Nerf war. I don't have a car, but I wouldn't mind paying a share of the fuel costs if anyone in the area were heading to a war in Texas.



#336354 Measuring Accuracy

Posted by Doom on 06 January 2014 - 09:45 AM in General Nerf

Once testing on the precision of any given Nerf blaster is underway, I'm fairly certain it will become a problem of proper blaster construction, barrel to plunger volume configurations, and dart-smithing. Not a calculation of MOA at 30 ft.


I'm confused. The standard deviation I mentioned can readily be converted to a MOA. If you want to make sure that your dart-blaster configuration is good then you'll have to do some testing. What don't you like about MOA aside from the fact that it's used in real firearms?



#336339 Measuring Accuracy

Posted by Doom on 05 January 2014 - 12:52 PM in General Nerf

I'm seeing some confusion of terminology here. Just so everyone is on the same page, let me reiterate the difference between precision and accuracy. Accuracy is how close an average shot is to the target. Precision is the variability between shots. Precision is the issue in Nerf. Wikipedia has some nice illustrations of this. Take home point: what people usually think of as accuracy is actually called precision.

In terms of measuring precision (not accuracy), I had planned a test two years ago. I recall others suggesting similar tests on SpudFiles or here years back. Find a long indoor area. Put some large sheets of paper (perhaps old newspaper) up on one end. Set up a gun that is aimed roughly at the center of the paper. This gun is at a set distance from the target. Lock down this gun such that it will not move when the trigger is pulled (clamps are one way to do this). Dip the tip of a dart in paint. Fire the gun at the wall many times. You can measure the location of the impacts from an arbitrary point (say, the center of the papers). From this, you can calculate the standard deviation of the impact locations. This'll give you an idea of how precise the gun-dart combination is.

There is no user error here, as this test does not measure accuracy (e.g., how close the average is to the target because there is no specific target point). It measures precision of the shot, that is, the variability. This variability is the issue in Nerf.

If you have some sighting device or something, you can measure accuracy of that system with the sight aimed at the target (or perhaps you eyeballing it), but I don't use sights, so I haven't thought much about that. You could more or less do the same sort of test, but instead of locking down the gun, you fire it yourself. If you eye-ball your shots, then accuracy is mostly a function of how good of a shot you are.

Who are "a lot of people"? Why are you under the assumption that 30 feet is the magical average engagement range?


30 feet seems concordant with my memory of when I took shots confidently at Nerf wars. A few years back, I had intended to watch a few rounds at local Nerf wars, take photos, and measure distances after the fact to get an idea of how far away most shots are taken. Until someone does that, we'll have to go off of what we remember.

As I recall, you'd need a lot of luck to get a hit at 50 feet or more. I can only recall one hit from over 100 feet away, and that was a total fluke.

You could construct some kind of structure that would keep the blasters level and aimed in the exact same way for every test, but that would take effort and resources and you would need a new one for every blaster since every blaster is shaped differently.


As mentioned, clamps locked down to a table work. And they can be used for basically every blaster.

In my test, the blasters don't need to be aimed at the exact same point. The tip of the barrel just needs to be the same distance from the target. The test only looks at variation from the center of the grouping, wherever that might be.

I think a dart-type accuracy test would be much more beneficial than a blaster accuracy test.


Hypothetically, you could design a gun to have as little barrel vibrations, muzzle blast, etc., variability as possible and do that. The problem is that it's really hard to eliminate all the variability from the gun. I had plans to make such a gun a while back, but I never got around to it.

You can arrange tests and use whatever philosophical rating you want to employ as your logic for such tests, but to what end? These are nerf blasters we're talking about. You can find some magical grouping or calculation of accuracy at 30 ft, but what is this going to accomplish?


If you don't see the value, then don't bother. Personally, I do see much value in designing a blaster that hits my intended target more often.

Speculating (no tests have been done), I think that what causes a blaster to be less accurate is mainly "barrel wobble" and muzzle blast.


In the notes Ivan S mention, I bring both of these up. No tests have been done to see what's worst, but I think for most blasters the muzzle blast is the worst effect.

While I believe testing blaster precision is a worthy endeavor, the intent is to meant for both person and blaster. I understand that one could make a very precise blasters and be a terrible shot. But the blaster precision data does him (specifically) no good, if he were to use the blaster.


A precision test is the most objective and useful test we can do. Improving precision also does the user a lot of good, knowing that a higher percentage of their shots will end up where they want them to.



#336059 Happy holidays

Posted by Doom on 26 December 2013 - 10:00 AM in News

Happy holidays everyone! I hope everyone had a great one! I wish it was colder here in SoCal. A 75 degree Christmas is not too great, but it is better than freezing.


I'm at my parents' near DC and it's been oddly warm here. I live in Austin, TX now and for a while it was warmer near DC than back in Texas! Felt weird. Though thankfully it did get colder on Christmas.

... And congrats to Doom on his 500th post!


Thanks. I thought I might have been the only one to notice. 500 posts in a decade is not very quick, but it sure shows dedication!



#336051 Happy holidays

Posted by Doom on 25 December 2013 - 10:32 PM in News

All of the NerfHaven staff wish our visitors a happy holidays, no matter what you celebrate. Merry Christmas, Happy New Year, Happy Hanukkah, and Nerf On.