Aluminium spears? anyone?

[panzerkrafft]

Thinking about making one with threaded tip when i get the time!

never heard or read about this subject!

Think that penetration will be suffering, but hoping for faster spear travel without overpowering of gun?

any experiance?

 

[foxfish]

I think you might find ally a bit flexy & a bit soft you will also have a very weak point if you cut a notch for a wishbone.

 

[alexrom1207]

Aluminum bends too easily as opposed to spring or carbon steel. Especially in the diameters that you'd be looking at for a spear, a little bit of torque when you hit a fish and that may be the end of the spear. There has been a lot of discussion on the use of aluminum (primarily because it's so cheap) and inevitably the idea gets scrapped. I have heard of titanium being used which is strong, flexible, and light....but that's pricey and I'm still not sure I think titanium will result in better performance than steel will. All a lighter spear will do is travel further and faster and perhaps carry a little more punch towards the end of its range.

The only use I can think of for this would be to give a short gun a longer range, however the downside is that with a lighter spear and a short gun your accuracy at distances is going to be very bad. If you need distance and have a bigger gun then the aluminum shaft is really pointless because with bigger guns and consequently bigger fish, aluminum is not going to pack enough punch to penetrate at distance. So in the end...there is really no application for the use of an aluminum spear that makes sense.

 

[Jonny250]

You could consider a carbon fibre spear with a bonded steel tip.

 

[alexrom1207]

Carbon fiber is not very impact resistant. It has a tendency to chip and flake if it gets banged hard, same with fiber glass. Did actually hear some information about a hollow spear a while back...I think on some fancy Italian gun. Now sure how that worked out.

 

[panzerkrafft]

What i'm planning to use is T6 aluminium which is similar to al/mg5 (marine) alloy
Thats pretty sturdy alloy, and then maybe go up to 7,5mm

Dont know what others might have used , but there's a huge difference in aluminium alloys in case of hardness , i'll atleast give it a try in near future

 

[panzerkrafft]

The idea of a lighter spear was for my 70cm gun ,
For me it's always tempting to use thicker bands to compensate the short acceleration lenght vs heavy spear,say 18/19mm, but in someway i imagine that thick band is slower acceletating than a thin say 16mm band,
(can someone confirm or reject that)
so..if i can lighten the spear the i can use a lighter and faster? rubber
and im willing to trade penetration for speed, but not accurasy for speed!
so, the accurasy would be the next question!

 

[panzerkrafft]

You could consider a carbon fibre spear with a bonded steel tip.

Yes it would definetly be an option,

But then, how is carbon fibre marketed if you want to buy round bars?

Are there any applications that would be similar to a spear?

 

[Old Man Dave]

carbon/stainless steel composite spears are available here Flèche tahitienne inox gainée Carbone Coralign Desiage Arbalète pièces

Dave.

 

[panzerkrafft]

carbon/stainless steel composite spears are available here Flèche tahitienne inox gainée Carbone Coralign Desiage Arbalète pièces

Dave.

Thanks dave ,

Unfortunatly, I dont think they would make it thru the swedish customs:yack

 

[speareasy]

Thanks dave ,

Unfortunatly, I dont think they would make it thru the swedish customs:yack

Yes, but if it was made from depleted uranium it would probably go through with no problems :t

 

[DivingDane]

having a lighter spear would result in a faster acceleration out of the un but VERY fast deceleration once power is no longer being transfured to the spear from the rubber, so long distance shots would be a no no, i think.

the overall mass of a spear is very important for both penatration and range. a heavier shaft will travel further and with the correct power be as accurate but with greater range and much nigher penetration.

carbon shaft are available as mentioned above and i have used them in an old JB Esclapez Concept pro i had and they are VERY accurate but do not last long around reef. they are a hybrid shaft with a 6.5mm cor shaft with carbon rapped arounf the shaft to build it up to 8mm (the tip and base are still straight SS to fit the mech and not explode on impact.

Titanium is nice but expensive but again any light shaft is only really suitable for thin fish. anything of serious size and the shaft will be near on useless (accept maybe if you shoot them in the eye).

DD

 

[Mr. X]

You could consider a carbon fibre spear with a bonded steel tip.

fibreglass with steel tip?

 

[DivingDane]

kinda like a small narrow handspear?

i would not have thought that the fibreglass would have enough structural rigidity to keep the shaft straight during the firing of the shaft, but purely speculating on this point.

DD

 

[Old Man Dave]

I'm guessing that there is an optimum weight (density) for a spear based on the contraction rate of the bands. It seems to me that it is the speed with which the bands contract dependant on their physical size, length and elastic modulus (type of rubber) that is THE factor.

Assuming the fastest contraction (speed) is with a zero weight/zero thickness spear and the slowest with a massive weight/huge diameter spear there is a point somewhere in between which offers optimum performance.

Now there are some other factors like spear stiffness as well as characteristics of the gun like stock stiffness plus line drag etc. However, while you could calculate velocities, hydrodynamics, energy , momentum, range, spear drop etc., etc., etc., it's far easier to derive data from actual testing.

What do we learn from all this? Well people have tested guns and generally there are set sizes of guns, bands and spears that in the right combination work. The only time your gonna improve on this is when your solution is better but was dismissed for a reason, like cost or perhaps durability.

Not being a killjoy but someone has been there done that and it didn't work. Suppose it's fun to learn for yourself though and you never know you might prove me wrong :t.

Dave.

 

[Ron Bakker]

If anything I would go for a heavier than steel spear as the weight behind the spear is what makes it travel, that's why the speargun has evolved into what it has.