740 replies to this topic

[stickfigure91x]

I was cruising around looking for disk shot mods, When I found this. As it turns out Piney has mage-like mind powers.

I'm reading the mixed reviews as usual, when the fall lineup is leaked out with minute details...

I guess the mention of the word "skeet" makes everyone think it may be crappy, instead if it were a "Nerf Sni.per" set or something with a silencer, or fully automatic belt-fed M-60 wannabes or something...

-Piney-

Creepy.

Edited by stickfigure91x, 29 February 2008 - 01:41 AM.

[laxtk88]

hornet Posted Yesterday, 02:21 PM
Holy carp! that comics said nerf on the bottom that must be talking about us.

Since when do we curse using fish names?

[Salmon]

Yeah hornet, don't insult my kind!

[oozinator]

I apologize for contributing to a topic that has brought so much anguish to others, but I’ve done some speculative calculations on the specifications of the Vulcan. Before I start addressing specific questions, I’d like to add a disclaimer that these calculations are done under ideal conditions for simplicity (friction, air loss, air resistance, weight of certain components are negligible, etc.) and with assumptions on the performance of the Vulcan. Among these assumptions are as follows.

1. The Vulcan priming mechanism is based on an airsoft AEG.
2. Mass of an average NERF or modified dart is 10 grams.
3. Radius of an average NERF or modified dart is 0.005 m = 0.5 cm = about 1/4 inches.
4. Gear is made of nylon engineering plastic (Wikipedia: density = 1.15 g/cm^3).
5. Radius of the gear is 1.5 cm = 0.015 m and 1.0 cm thick.
6. Mass of the gear is roughly 8 grams = 0.008 kg. (Calculated from assumptions 4 & 5)
7. Only 1 gear is used.
8. Dart falls 1 meter after traveling 9 meters (~30 feet)
9. The Vulcan’s pull length is 3 inches (0.0762 m).
10. The Vulcan pull length is the spring compression length.
11. A springer plunger works like an ideal mechanical piston.

Certain figures are also rounded, and calculations are non-integrative (no background in Calculus required, only physics).

So what do we know:

Shots per second = 3.5 (calculated by Secran)
Energy source = 6 x 1.5V D cell batteries in series = 9V

What I’ve speculated out:

Volume of air used:

Chamber volume = (Cross-sectional area of dart) x (pull length)
= (pi)(0.005 m)^2 x (0.0762 m)
= 5.98 x 10^-6 cubic meters

Work per shot (dynamic change of pressure discounted):

Work per shot = (chamber/atmospheric pressure) x (volume displaced)
= (101325 Pa) x (5.98 x 10^-6 cubic meters)
= 0.606 J

Work per second (Power):

Work per second = (work per shot) x (shots per second)
= (0.606 J/shot) x (3.5 shots/s)
= 2.121 J/s

Muzzle velocity (acceleration of the dart in the barrel is discounted):

0.5 x (mass of dart) x (muzzle velocity)^2 = work per shot
muzzle velocity = 2 x (work per shot) / (mass of dart)
muzzle velocity = [2 x (2.121 J/s) / (0.01 kg)]^(1/2)
muzzle velocity = 20.596 m/s = 46.07 mph

OR kinematically, under assumption 8,

(drop height) = 0.5 x (acceleration due to gravity) x (time of flight)^2

(time of flight) = [2 x (drop height) / (acceleration due to gravity)]^(1/2)

= [2 x (1 m) / (9.8 m/(s^2))]^(1/2)
(time of flight) = 0.452 s

muzzle velocity = (distance traveled) / (time of flight)
= (9 m) / (0.452s)
= 19.9 m / s = 44.5 mph

The speeds are relatively close, so my assumption on the figures and range are nearly accurate.

Revolution speed:

The electrical work done by the motor in a loss-less system should equal the rotation energy of the gear.

Work per shot = (0.5) x (moment of inertia of gear) x (revolution speed in rad/s)^2
Revolution speed = [2 x (work per shot) / (moment of inertia of gear)]^(1/2)
Revolution speed = [[2 x (work per shot) / [0.5 x (mass of gear) x (radius of gear)^2]]^(1/2)
Revolution speed = [2 x (2.121 J) / [0.5 x (0.008 kg) x (0.015 m)^2]]^(1/2)
Revolution speed = 2171 radians/second
Revolution speed/(2 x pi) = 345.53 rpm = 5.76 rps

Cocking time:
Cocking time = (pull length) / [(revolution speed in rps) x (circumference of gear)]
Cocking time = (0.0762 m) / [(5.76 revolution/second) x (2 x pi x (radius of gear))]
Cocking time = (0.0762 m) / [(5.76 revolution/second) x (2 x pi x (0.015m))]
Cocking time = 0.14 seconds

Plunger travel time = (1/3.5 seconds/shot) – Cocking time = 0.1457 seconds

Electrical Current of Motor:
Current = (Power) / (Voltage)
Current = (2.121 J/s) / (9 V)
Current = 0.235 A or roughly 0.25 A

Notes: This current rating is somewhat idealistic. I think 1 A might be more realistic.

Spring constant:

Work per shot = 0.5 x (spring constant) x (plunger length)^2
Spring constant = 2 x (work per shot) / (plunger length)^2
Spring constant = 2 x (2.121 J/s) / (0.0762 m)^2
Spring constant = 730.57 N/m = 4.17 lbs/inch

It seems battery life and cost per shot is a major concern among nerfers, so everything pertaining to that subject is summarized here. Keep in mind that the data on battery life is very speculative. At some point, voltage will decrease significantly in the battery and become useless. You might be very lucky to even attain half the shots estimated here. All values are taken from http://www.andybaird.../batteries.html.

Shots per 6 batteries (with estimated current of 0.25A):
Shots per 6 batteries = (battery life in hours) x (shots per second) x (3600 seconds per hour)

Alkaline*: 20160 shots
Lithium*: 100800 shots
NiMH: 37800 - 63000 shots
NiCd: 25200 shots
Alkaline Rechargeable: 12096 shots

Cost per shot (with estimated current of 0.25A):
Cost per shot = 6 batteries x (cost per battery) / (shots per 6 batteries)

Alkaline*: 0.0074 – 0.0223 cents
Lithium*: 0.00893 – 0.021 cents
NiMH: 0.0214 – 0.091 cents
NiCd: 0.06 cents
Alkaline Rechargeable: 0.087 – 0.149 cents

Shots per 6 batteries (with probable current of 1A):

Alkaline*: 5040 shots
Lithium*: 25200 shots
NiMH: 9450 -15750 shots
NiCd: 6300 shots
Alkaline Rechargeable: 3024 shots

Cost per shot (with probable current of 1A):

Alkaline*: 0.030 – 0.089 cents
Lithium*: 0.0357 – 0.0833 cents
NiMH: 0.0857 – 0.365 cents
NiCd: 0.238 cents
Alkaline Rechargeable: 0.3472 – 0.595 cents

*Non-rechargeable
** Prices are U.S. cents.

What seems really skeptical for me is the cocking time because it’s about as quick as the plunger travel time. I would think that the plunger travel time should be significantly faster. This is probably due to the fact that the calculations of the time are done using arbitrary dimensions for the gear. The battery life in terms of shots seems to be really high as well, even at the probable 1A setting. It’s likely, however, that the effective battery life will be much shorter. Because the “work per shot” figure was used to calculate the “shots per 6 batteries” figure, the work per shot figure and the power figure are also suspect. I think the only reliable figure I would stick to my guns on would be the muzzle velocity and range figures. They seem pretty nerf to me. Same with the spring constant.
Again this is all theory and ultra-simplified. If anyone has any actual experience on this or notices any mistakes/major issues to address, please give me some feedback.

Unit conversions were done using the applets at http://www.digitaldutch.com.

[Kenpachi Taicho]

Wow ooz, that's quite the post. For starters, I definitely respect the level of technicality along with actually addressing your assumptions before you delved into your dubious quantity (with lots of quality) of calculations. This is still just theory, and I'm kinda surprised you took that much time and effort to speculate. Why not just wait until you have one in your hands, then you don't have to assume anything and your calculations will be more useful. To me your post was a little bittersweet. Awesome level of intellect went into it, however it was kind of a waste of time on your part. I think Assumptions 5 and 9 might be a little large, and this has left you without justification on the time you just wasted proving that you know physics. But I guess if you have to waste your time implimenting something that you've learned, why not apply them to nerf.....I guess that's a good choice.

EDIT: For clarification.....I'm not a "nay-sayer". Infact I'm "patting you on the back" for putting soo much effort (with a good level of intellect) into nerf, irregardless of the vastness of the assumptions.

Edited by Kenpachi_Taicho, 01 March 2008 - 02:06 PM.

[Kabuki]

Wow... Ooze, that is one detailed post. It will be interesting to see how close your estimates are to the actual measurements that will be taken at a later date. Don't be discouraged by the nay-sayers, for in all honesty, this entire thread is wild speculation and a complete waste of time. Your post is one of the few that have any worthwhile analysis.

[OfAllTheNerf]

Yeah, in all honesty 90% of the posts in these threads are gayer than eating a sweaty condom.

[Scotch]

I hate to be a hypocrite.

But There are 420 posts here! We all know the gun is going to suck, it's just not worth posting!

Half of you people aren't even posting about Nerf, let alone The Vulcan!

If I could close this I would, but I can't.

EDIT: Holy Shit oozinator. That is probably the most helpful post so far.

Edited by Scotch, 01 March 2008 - 10:04 AM.

[Blasphemy]

We all know the gun is going to suck, it's just not worth posting!

I'm sorry, but I didn't know this gun was going to suck. Apparently I missed the memo, did Hasbro do a press release where they already stated the Vulcan would suck. We still don't know exactly how it works, and last I checked you didn't either, unless you failed to post something, so why did you say that, it just seemed plain stupid. I recommend that anyone that decides to post something like this about the Vulcan that passes definitive judgement on it back it up with hard evidence. Until anyone can do that I fail to see the point of them posting at all, so don't do it. I'm not defending those who think this gun is going to be good, nor those who think it is going to be terrible, frankly, I think everyone should forget about it until it pops up in their local toy stores, they crack it open and do a modification on it.

[oozinator]

Thanks for the feedback guys. I originally intended my last post to provide some insight on the feasibility of a system like the Vulcan. As for the assumptions messing up the estimates, I believe that some of the work could still be salvaged. For the most part, the calculations weren't all too fanciful and if any corrections in numbers are needed, the template is already in place to make those adjustments.

I was hoping anyway that one of these crazy engineering majors lurking around would help bring better estimates to light or perhaps, if he's brave enough, he would even try to tweak with the dimensions of the theoretical components to design (and possibly build) a better, homemade version of the Vulcan. For too long, I've seen posts saying that it can't be done (at least to attain the ranges of a conventional springer or air gun), but news of the Vulcan brings some glimmer of hope that we have not hit the technological ceiling with bolt-actions, pneumatic semi-autos, flywheel guns, and pneumatic autos that must be reprimed with each trigger pull (ie. RF20)

A modified Vulcan would probably be the predecessor of future automatic Nerf guns, but I think that if nerfers have access to a projection of the technical data and dimensions of such a system, it would help spur the development of homemades in this area. And that would just plain rock.

[saxynerfer]

ozzinator's massively intelligent post / calculations

I think we have the next CaptainSlug here folks.

[Peter]

<PHYSICS PHUN REMOVED>

That really wasn't too useful yet, because almost all of it is based on speculative physics without proving or disproving anything, it's a veritable wall of text if you ask me. All that info is pretty useless, and pretty much conjured. It would've been better to wait for it to come out, then TEST IT. High school physics doesn't have much use in nerf.

[Pineapple]

ozzinator's massively intelligent post / calculations

I think we have the next CaptainSlug here folks.

When he actually builds something, I will agree.

Until then, impressive, but pretty useless until the actual Vulcan can be tested out.



-Piney-

[One Man Clan]

Useless is the key word here. I can speculate all I want to. I really hope this guys calculations fall flat on it's face, just so everyone can see how stupid it is to make assumptions and guess what the Vulcan will be all about.

[CaptainSlug]

I think we have the next CaptainSlug here folks.

How dare you accuse me of being good at math. Preposterous.

[donz2323]

From my noob observations, by you assuming that friction is zero almost makes your calculations completely useless. Some obvious problems include not accounting for friction on the dart which you used to estimate the force needed to push the dart. The inability ot have numbers for this will make further calculations inaccurate. Second you also assume that this nerf machine is 100% efficient, which could not possible be further the truth. due to friction of moving parts(and there are losts of them), I won't speuclate on efficiency but I assume 30% is probably high.

However the vulcan isn't released yet, and I guess everyone on here can sling a little BS.

[Omega]

Yeah, and that is one hell of a lot of assumptions. I don't think anyone swooning over the physics (which would be quite stunning if they were likely accurate at all) knows how many assumptions that is. Every time you make an assumption in an equation (assumption being a statement treated as fact which hasn't been demonstrated by hard fact or by a law of mathematics) it throws you off.

The physics, while damn impressive before you really think about them, are useless.

[Peter]

In a physics fantasy land, where there exists no friction or air resistance, and where the nerf gun itself is %100 efficient, his calculations might not be far off, the math itself is right, it's just that the application of it is wrong.

[ultra920]

ozzinator's massively intelligent post / calculations

I think we have the next CaptainSlug here folks.

PFF, please. He obviously used a calculator.

With the friction, i would assume it is low unless they have a weird barrel(stuff jetting into the dart).

"Muzzle velocity (acceleration of the dart in the barrel is discounted"

That'll set it off.

"At some point, voltage will decrease significantly in the battery and become useless. You might be very lucky to even attain half the shots estimated here"

And that.

And, i would have a feeling the stock range is 23-28 feet. Not sure why. Just a gut feeling.

[Peter]

ozzinator's massively intelligent post / calculations

I think we have the next CaptainSlug here folks.

PFF, please. He obviously used a calculator.

With the friction, i would assume it is low unless they have a weird barrel(stuff jetting into the dart).

"Muzzle velocity (acceleration of the dart in the barrel is discounted"

That'll set it off.

"At some point, voltage will decrease significantly in the battery and become useless. You might be very lucky to even attain half the shots estimated here"

And that.

And, i would have a feeling the stock range is 23-28 feet. Not sure why. Just a gut feeling.

Friction affects nerf guns quite a bit, that is probably the thing that threw it off the most.

[sourskttles772]

ozzinator's massively intelligent post / calculations

I think we have the next CaptainSlug here folks.

PFF, please. He obviously used a calculator.

With the friction, i would assume it is low unless they have a weird barrel(stuff jetting into the dart).

"Muzzle velocity (acceleration of the dart in the barrel is discounted"

That'll set it off.

"At some point, voltage will decrease significantly in the battery and become useless. You might be very lucky to even attain half the shots estimated here"

And that.

And, i would have a feeling the stock range is 23-28 feet. Not sure why. Just a gut feeling.

Friction affects nerf guns quite a bit, that is probably the thing that threw it off the most.

Im just throwing this out there but I think this gun will have high stock ranges.

[Scotch]

This may have all ready been posted but I'm not about to look through 30 pages.



This may be computer generated, probably, but there is no chain in the gun when he is firring it.

There may be a single-shot mode, but chances are this is a computer generated image.

Oh buy the way did you know that the Nerf Vulcan is based on the M61 Vulcan?

[Peter]

This may have all ready been posted but I'm not about to look through 30 pages.



This may be computer generated, probably, but there is no chain in the gun when he is firring it.

There may be a single-shot mode, but chances are this is a computer generated image.

Oh buy the way did you know that the Nerf Vulcan is based on the M61 Vulcan?

Doesn't look computer generated to me, and you realise that he could have just fired the first shot so no chain would have been expelled yet?


Other than name and belt-fed, the two have little in common with eachother. If anything, the Nerf Vulcan more closely resembles an M60.

[CaptainSlug]

Oh buy the way did you know that the Nerf Vulcan is based on the M61 Vulcan?

I would love to know where you're getting these misspelled and inaccurate "facts" from. I'm guessing they're from somewhere in the Gluteus Maximus region. (i.e. out of your ass)
The Nerf Vulcan is based on belt-fed machine guns in general. You can poke through world.guns.ru all you want, but as far as anyone can tell it's still not based on anything specific. It kinda-sorta like a lot of them, the XM312 being the closest visually. But who cares.

Edited by CaptainSlug, 04 March 2008 - 10:18 PM.

[Captain]

I think perhaps all the pictures we have found should be put in the first post for all to see, so we don't get any more people saying stuff like:
"hey look guise, I found sum pix, LOL."
Because they weren't there to see them posted first, or are too lazy to look through the thread.
It would generally makes things a lot easier.

EDIT: This is not directed at you, Scotch, mostly the idiot who started a whole separate thread to share one picture that everyone's seen already.

Edited by Captain, 04 March 2008 - 09:46 PM.