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Nerf Dart Gun Challenge (now open) disscussion thread

All non-spudgun related discussion goes here such as projects, theories, serious questions, etc. All "off-topic" posts (aka useless posting, determined by moderators) will be removed.
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Are you intrested in participating in this challenge?

I'd like to participate in this challenge
16
46%
I think this is a good idea, I might participate
15
43%
I don't like the idea of this challenge
4
11%
 
Total votes : 35
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Unread postAuthor: kenbo0422 » Thu Nov 19, 2009 12:06 pm

How about a standards category: Using the standard nerf dart bought from the store. Would they be fairly common and standardized? It would take some of the guesswork out of how to make the perfect dart for the gun by just designing the gun around the (standard) dart.
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Unread postAuthor: btrettel » Thu Nov 19, 2009 9:39 pm

Below is a bit about how I think the contest should be run.

How is the winner to be chosen though? As I recall the official contests here have a semi-private stage where some judges determine which guns should be voted on in public. Should we do something like that?

I'm also debating whether or not something as explicit as the KED limit is appropriate for the contest. Safety is an important issue, but I fear some people don't have the chronometer and small scale necessary to determine KED.

Thoughts?

@kenbo0422

I'd like to keep the competition fairly open ended. Most people here likely prefer homemade darts because they are cheaper, more customizable, or for some other reason. That would be an interesting angle, yes, but it wouldn't work well with what I have planned as store bought darts are very loose in my aluminum barrels.

----------

Nerf contest/challenge

This challenge is simple: to build the best Nerf gun you can. Whether it shoots micro darts or big foam missiles, it is game.

Deadline: March 1st

Judging

(Based in part on what ilovetoblowthingsup has suggested.)

1) Effectiveness. Accuracy, rate of fire, range, efficiency, and how well the gun appeared to handle would be my concerns. There are, of course, other potential concerns.

2) Reliability. This really goes under effectiveness but its important enough to warrant its own category. A semi-automatic gun (as I suspect most here are looking to make) is worthless unless it is reliable.

3) Aesthetics. Doing all of the above in style never hurts.

4) Innovation. Introducing some new ideas should be a stated goal of the competition.

5) Safety. Safety is a paramount issue in Nerf and making it a category to be judged upon only reinforces that thought.

Safety

There are two parts to safety that will be judged upon: terminal ballistics and material safety.

Any sort of foam dart may be used provided that 1) the impact surface is not hard and 2) the projectile's KED is below the maximum defined below. An example of an acceptable micro dart is the "Slug dart": http://www.youtube.com/watch?v=7EBtyXCsnKo

The maximum KED is 0.015 J/mm^2. This is equivalent to a micro dart (0.53 inch diameter) with a mass of 1.1 grams and a velocity of 62 m/s. KED is defined as the kinetic energy (0.5 m * v ^ 2) divided by impact area. The higher the KED, the more a material will deform upon impact. For a circular cross section dart is is defined below.

KED = (2 * m * v ^ 2) / (pi * d ^ 2)

where
m is the dart mass
v is the dart velocity
pi is 3.141592...
d is the dart diameter

An example for m = 1.1e-3 kg (1.1 g), v = 62 m/s, and d = 13.46 mm...

KED = [2 * (1.1e-3 kg) * (62 m/s) ^ 2] / [3.141592 * (13.46 mm) ^ 2]

...reduces to...

KED = 0.01485 J / mm^2

Note that the dart diameter is the minimum dart area. If the tip tapers, the thinnest part must be used. Flat tips are best from this standpoint, but they have a relatively higher drag coefficient.

All materials must be used with an appropriate safety factor and/or known pressure ratings must not be exceeded.
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Unread postAuthor: JDP12 » Thu Nov 19, 2009 11:15 pm

Dang trettel... Impressive
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Unread postAuthor: SEAKING9006 » Sat Nov 21, 2009 8:41 pm

I'll have to withdraw from the contest. Recent events have proven to be far from fortuitous, and I find myself without the capability to participate. I won't be able to return to the forum for quite some time, either. Best of luck to the rest of the participants.
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Unread postAuthor: iknowmy3tables » Sun Nov 22, 2009 7:58 pm

could we set an alternative such as a max range flat from 5 feet above the ground with standard darts, so we don't scare off anyone who'd rather not calculate KED, I'm really favoring the idea of measuring performance with a store bought dart
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Unread postAuthor: roboman » Sun Nov 22, 2009 8:29 pm

iknowmy3tables wrote:could we set an alternative such as a max range flat from 5 feet above the ground with standard darts, so we don't scare off anyone who'd rather not calculate KED, I'm really favoring the idea of measuring performance with a store bought dart


Standard darts can cause problems with high-powered guns. Recently, I modded an AirTech 2000 (AT2K) with a basic CPVC turret, and it was capable of actually blowing the tips off of stock darts. Sometimes, the foam part never left the barrel.

This is a stock AT2K (not my pic):
Image
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Unread postAuthor: iknowmy3tables » Sun Nov 22, 2009 11:00 pm

I see though I would blame that on the tightness of the cpvc, but anyways do we really need such a complex system for saftey, we don't evaluate safety for other contests and what we use them for is our own business, can we just eliminate any gun that tries to make an appeal with dangerous power during the 1st round
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Unread postAuthor: btrettel » Sun Nov 22, 2009 11:49 pm

No very specific safety limits for the darts then. I was thinking people wouldn't be able to work with KED because some are scared of math or because they lacked a chronometer and scale. If something seems dangerous I'm sure someone will point it out as has been said.

Stock darts don't always fit in barrels as well. The aluminum I use is fairly loose on streamlines but it fits the FBR I can find pretty well.
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Unread postAuthor: iknowmy3tables » Mon Nov 23, 2009 12:45 am

who shall run the competition, do we have any neutral officers?
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Unread postAuthor: JDP12 » Tue Nov 24, 2009 11:24 am

ok just a warning... I dunno if I will be able to do this contest anymore.

My money is rapidly drying up, and with no money coming in and very little time I'm not sure if i will be participating.
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Unread postAuthor: iknowmy3tables » Tue Nov 24, 2009 4:28 pm

do your relatives send you anything during the holiday seasons? that's income for me, though it's pretty pathetic at my age, you could try a clever cheapy design
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Unread postAuthor: kenbo0422 » Tue Nov 24, 2009 9:59 pm

We're talking nerf... How much money do you really have to spend? Most of the stuff to launch a piece of foam could even be cardboard tubes. It was my favorite way to pass the time on a rainy day as a kid, and finally get into trouble for antagonizing my sister... :roll:
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Unread postAuthor: JDP12 » Wed Nov 25, 2009 9:05 pm

alright i'm back in...

and busy designing :D :D
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Unread postAuthor: Moonbogg » Thu Nov 26, 2009 1:51 am

Hmm. Will hybrids be accepted?
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Unread postAuthor: inonickname » Thu Nov 26, 2009 4:24 am

Moonbogg wrote:Hmm. Will hybrids be accepted?


Many nerf players have little to no understanding of science and many lack common sense. You could modify a small weed-whacker engine and use the exhaust gasses to power a full-automatic nerf gun. The nerf community wouldn't like it as they hate pneumatics, let alone "omfg explosion guns". Then again a week whacker isn't very stealthy. Perhaps a fixed machine gun to mow down players at a choke point.

You could also make hybrid cartridges, the volume needed would be TINY for average nerf performance.
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