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What's your Holy Grail of Spudguns?

A place to ask general spud cannon related questions.
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Unread postAuthor: MrCrowley » Sun Jan 13, 2008 10:07 pm

Ragnarok wrote:@JSR: Not really, if I get my 30 bar mods done, with HEAL and a dart, a trajectory of 3 degrees would get it out to 500 metres, or so GGDT and my range calculator tell me.

The range calculator is pretty accurate, I can't fault it's predictions, but it still has a few last bugs to handle before I'm happy about releasing it. Sorry to keep it from you for so long, for that I apologise, but I want to get it all as streamlined as I can first, I'm a bit more of a perfectionist than my relatives.


I really don't see a dart going 500m from HEAL with only a 3* trajectory.

If you look at something like an arrow, which is similar to a dart, it needs a huge trajectory to get a fair distance.

I just don't think it possible at only 435psi with HEAL and a dart.

I'm sure you can shoot 500m, but not at that trajectory.
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Unread postAuthor: Isomer » Sun Jan 13, 2008 10:58 pm

My holy grail(s):
-Piston hybrid (eliminate burst disk reloading) that can completely be controlled remotely or from the handle of a hand-held-
electronic propane injection and pressurization+trigger(obviously) even better if its semi or full auto
-A high-powered pneumatic that uses cartridges containing the air and projectile. This would make auto much easier and allow for portability.
-Not really a holy grail gun but would be awesome: If Lowe's/Home Depot started to stock SDR21, schedule 80/120 pvc, larger pressure rated pipe (2.5"-6") including fittings, and QEV's from .25" to 2" lol (does it even exist)
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Unread postAuthor: Ragnarok » Sun Jan 13, 2008 11:04 pm

MrCrowley wrote:I really don't see a dart going 500m from HEAL with only a 3* trajectory.

Well, the dart would be doing nearly 800 fps.

It sounds about the right sort of value to me. At 800 fps, even with drag, the dart should take under 2.5 seconds to reach the target.
Drop in 2.5 seconds is about 30 metres
The tan(3) * 500 metres [which calculates the distance the round would rise without gravity] is 26.2m.
Both those numbers in the same sort of region, especially when you consider the drop is likely to have been overestimated, which tells me it's probably about right. At 4 or 5 degrees, the numbers show it should be more than possible, so the estimate of 3 is probably about right.
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Unread postAuthor: MrCrowley » Sun Jan 13, 2008 11:12 pm

2.5s to go 500m :shock:

I'd like to see that.

Anyway once the mods are done, and you find 500m of flat land, let me know :)
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Unread postAuthor: markieclarkie » Sun Jan 13, 2008 11:56 pm

A semi auto magazine fed water balloon launcher. To keep the flow of ammo going, some pressure would have to be fed into the magazine.(somehow).
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Unread postAuthor: jackssmirkingrevenge » Mon Jan 14, 2008 12:55 am

A 1 gram lead pellet at 900 feet per second drops several feet at 120 metres, I think you're underestimating the effects of drag on your projectile here. Three degrees doesn't sound right.
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Unread postAuthor: TwitchTheAussie » Mon Jan 14, 2008 1:39 am

My holy grails in the making. I just need a welder :cry:
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Unread postAuthor: rna_duelers » Mon Jan 14, 2008 1:49 am

TwitchTheAussie wrote:My holy grails in the making. I just need a welder :cry:


So do I,and some Aluminium parts.
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Unread postAuthor: ALIHISGREAT » Mon Jan 14, 2008 2:45 am

At 4 or 5 degrees, the numbers show it should be more than possible, so the estimate of 3 is probably about right.


3 degrees seems too little... *gets protractor to check* :lol: yeah i would shoot at like 10degrees.

i wonder how far i could shoot a 1000fps paintball...
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Unread postAuthor: MrCrowley » Mon Jan 14, 2008 3:57 am

Well it's not like he can shoot it at exactly 3* anyway, but that's not the point. I just highly doubt it's possible with HEAL, those pressures, 3* and a dart.

Oh and is 800fps the muzzle velocity or average velocity? Because it ain't gonna stay at 800fps the whole time. If 800fps is the average you're ok, but you can't use the muzzle velocity to calculate drag, the parabola (projectile curve) and time to impact. And most importantly in this case, your firing angle.
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Unread postAuthor: jackssmirkingrevenge » Mon Jan 14, 2008 4:58 am

At 500 yards, a 150 grain bullet leaving the muzzle of a 30-06 rifle at 2,700 feet per second will drop almost seven feet from the line of bore, I think Ragnarok is being just a little too optimistic.
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Unread postAuthor: rna_duelers » Mon Jan 14, 2008 5:25 am

Ok I have found my Holy Grail. . .Carbon Fiber/Carbon Kevlar constructed pneumatic launcher.
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Unread postAuthor: Ragnarok » Mon Jan 14, 2008 5:49 am

To go 500 metres in 2.5 seconds, I'd need an average speed of 200 metres a second. If I'm launching a low drag dart at 240, I don't think that 200 m/s average is hopelessly optimistic.

What I'm using for the calculations is a souped up version of the Launcher Range Calculator - and it's much more powerful.

I've accounted for the temperature, pressure and humidity of the atmosphere - even how it thins with altitude as the projectile rises - I'm calculating drag vertically and horizontally, using a 0.1ms interval for the calculations.
I've checked the maths I'm using twice, and I think it's right. I'll release it soon, then you lot can scrutinise it for mistakes.

@ALI: Not hugely far I would say, paintballs have low sectional density, and slow down pretty fast.
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Unread postAuthor: jackssmirkingrevenge » Mon Jan 14, 2008 6:02 am

I'm not saying you won't make it to 500 metres, looking at some longbow statistics makes such a figure believable for a high pressure pneumatic launcher, but not at three degrees of elevation.
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Unread postAuthor: rna_duelers » Mon Jan 14, 2008 6:17 am

I'm 100% on the side that says it won't make .5km at 3 degrees elevation,I can make 500m easily with a golfball gun but with 3 degrees of elevation from a small projectile even at around 800fps it doesn't seem right.
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