SpudFiles

Firstly, I apologise for opening with such a terrible and obvious pun.

This "rant" is prompted mostly by this post by MrCrowley - an experienced fabricator who has made some pretty impressive spudgun powerhouses - expressing amazement at the performance of a pneumatic launcher designed almost a century ago.

I've said this several times but I'll say it again, most of the members of this forum put a heck of a lot of effort in designing and building their launchers, then proceed to launch "anything that fits in the barrel". I enjoy this too, and it's undeniably one of the fun elements of the hobby. However, for those who enjoy pushing the envelope, it simply won't do.

It's understandable that one would be unwilling to put much effort into something that is going to be fired and will most likely perish, and I'm not suggesting "regular" ammunition should be so finely made, but it would be good to see some one-offs in the interest of exploring the performance potential of our creations.

I believe that with optimised projectiles, ranges well beyond one and even two miles are more than feasible, even with launchers that aren't necessarily the size of this monster.

Unfortunately I don't have the facility to shoot safely over such distances, and perhaps this is what prompts indignation at the fact that those with open acres sprawling at their feet do not take advantage of them.

I was contemplating sponsoring a contest for furthest distance but sadly, independently verifying claims would be a nightmare. Still, it would be interesting to see some attempts at distance records.

In terms of projectile design, I think the factors needed for good performance are well understood - a projectile should be light enough for high muzzle velocity, but should also have high sectional density and minimal drag. A discarding sabot design would seem ideal, but not obligatory.

One of the most challenging aspects though would be locating the fired projectile, some non-pyrotechnic ideas spring to mind:

- chemical or electrical light on the tail of the projectile and shooting at night: this might present safety hazard as it will be more difficult to determine that the shooting area is clear, as well as the need for the light source to survive impact with the ground

- a fine powder which would give a puff of smoke on impact

- gps tracker

- radio beacon as used to recover free flight model aircraft

- acoustic beacon

Any electronic solutions present their own hazards, frankly it would be better to use a device that relies on the projectile breaking in order to function as opposed to hoping it remains intact, especially if you're lobbing expensive tracking devices into the air.

Just my 0.02 euro cents, any thoughts?

I would absolutely love to participate. I have some areas near my house with a few kilometres free range.

I could pressurize my gun to >15 bars (taking quite a while ) and buy a 5 meter barrel.

I have access to a machine shop with lathes, mills, welding equipment and some other stuff.

I also know some people that would be able to construct a radio beacon, as I am not willling (or able) to spend a lot of money on it.

I could also attach some pyrotechnical device (altough against the rules) to help locating it.



If I have the time, money and ability, I would also like to construct some pneumatic mortar....

chemical or electrical light on the tail of the projectile and shooting at night: this might present safety hazard as it will be more difficult to determine that the shooting area is clear, as well as the need for the light source to survive impact with the ground

Been there done that
http://www.spudfiles.com/forums/light-b ... rt,15.html


There are lighters with a small inbuilt LED flashlight (essentially just an LED, button and a battery). You just have to unscrew one bolt to get the whole module... then tape it in transparent tape and you've got an indestructible tracer

This -> http://en.wikipedia.org/wiki/Blinky_%28novelty%29 is probably also an option... never tested one but probably it can survive the launch

Anybody serious enough should have no problems finding projectiles at extended ranges. Three words: Black Rock Desert. Out there the hobby rocketry crowd has recovered rockets that went up to 42 *miles* in altitude. How? Well... It's a big lake bed. Pretty easy to find stuff there. Finding something from a spud gun should be trivial by comparison.

Oh, and yes, it's the same place they do Burning Man.

launching something smelly maybe? a stinkbomb?

Seriously the other day I've seen at WalMart some lighted arrows. Very small and designed to resist impact I guess.
If I'm not mistaken it was something like that:

http://www.youtube.com/watch?v=mO7DZJ79ZIA

You would have to be a pretty hardcore spud gunner to drive across the country just to shoot a cannon into the desert.

Large spaces tend to swallow up small objects. One time I was range testing the Mouse Musket using brightly colored gumballs in a huge empty parking lot. It was amazing how many I still managed to never find. You would think a gumball would be easy to find in a large paved lot. Wrong..

Long range golf ball shots are even harder to find, even in the desert or plowed field.


There are 6 sprinkler marker flags by the arrow. They are bright flourescent colors about 8 inches above the ground. This is from some of the low power close in shots. The landing zone becomes quite large at distance.

Markers for some golf balls and apples. The markers are just past the power lines. The power lines are about 1/2 way to the road at the far end of the field. For size comparison, the powerline towers on the left side are closer than the flags.

Telephoto shot of two of the flags. One is blue and one is red.

jackssmirkingrevenge wrote:I believe that with optimised projectiles, ranges well beyond one and even two miles are more than feasible, even with launchers that aren't necessarily the size of this monster.

Personally, I think Jagerbond has made great design gains with his Compound Round design.

The target @110yrds was composed of 20 years of sun dried trailer deck 1.5" thick with .5" OSB backing. The 32mm round fired using "iron sights" and cross wind demonstrates good accuracy with an abundance of energy down range.

IMO, total distance shouldn't be the sole objective in designing a projectile. A round should be accurate enough to strike a selected target and pack enough energy to do some "work" when it encounters that target.
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If a sufficiently large launch area is a problem the round can alway just be fired nearly vertically. Hang time and the Cd (or measure the muzzle velocity and calculate the Cd) will tell you about both the power of the launcher and the flight characteristics of the ammo.

The only thing you loose when firing nearly straight up is that any ammo that generates it's own lift (like a properly spun golf ball) won't exhibit much lift when fired this way, though it will displace laterally more than a non-lift round.

I was in brief talks with Ragnarok about designing a projectile that could achieve distances of about 2km+ but I never got around to actually getting something on paper or making one. I'd have to get it fabricated and I wouldn't like to pay for that to be done and this current time (being a broke student and all!)

It would've been fired out of my piston hybrid. I have only one place I could really test it, a 2 mile beach about 80 minutes from where I live. It's more or less dead straight but is only 30m wide with the ocean on one side (duh) and sand dunes covered in foliage on the other.

@MrCrowley

I'd have to get it fabricated and I wouldn't like to pay for that to be done and this current

Who said you need expensive ammo to achieve long range??

Well I figured i'd have to make the 'dart' from welded steel rods or something. Unless you have a better idea haha?

Yeah that's what I was thinking about... though who said you can't build one yourself ?

anyway you might as well use drag stabilised ammo... get, let say a
10cm X diam. 20mm steel rod and sleeve it into 30cm lenght of PVC pipe

I wouldn't know where to buy steel rod and I can't weld and don't know anyone who can. There's a mag repair shop not far from me that I've held weld some stuff for me. Usually you can give them a 12pk of beer or $20 and they'll weld the odd job for you.

You think it's better to go with a drag stabilised projectile over a fin stabilised projectile? I guess that would be much easier and cheaper to construct, as long as it keeps the drag coefficient down it should be fine. How difficult is it to construct very low drag projectiles and what would a good drag coefficient be for shooting long distances?

Hmm I think that something along these lines should be enough... sure it isn't optimal as far as cd value is concerned, but as long as it stays stable in flight and has high mass then it should be ok