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Arbalete Pneumatico Santino

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popgun pete

popgun pete

Well-Known Member
Jul 30, 2008
3,035
590
153
Australia
Maybe this is the muzzle port here, being used as a sort of muzzle compensator by directing a water jet upwards.
muzzle port maybe.jpg

This feature does not appear on the earlier muzzle which would make sense if it was a vacuum barrel shooting bare tail spears.
Santino muzzle.jpg
 
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popgun pete

popgun pete

Well-Known Member
Jul 30, 2008
3,035
590
153
Australia
More views of the gun showing how the trigger mechanism fits into the stock, it being integral with the barrel and tank as a sub structure, and what I assume is a frictionally loaded side-mounted line release.
Santino handle details.jpg

Santino rhs and line release.jpg

The line release pivot is related to the black item forward of the reel axle and may be a rubber friction block.
 
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popgun pete

popgun pete

Well-Known Member
Jul 30, 2008
3,035
590
153
Australia
I suppose so too. There are neither water escape ports as usual. Water must escape forward with the spear...
Next I suppose that the compression ratio is probably CR > 2.5
I made an estimation using my speed-energy calculator. For the longest model speargun, 120 cm a suppsed the working couse of the piston to be 115 cm (maybe it is less, 110 cm?). On 11.76 bar (12 at) with CR=2.5 if the spear weight had been 361 g the initial speed of the spear would be about 34 m/s.
Initial loading effort 12 kgf and final loading effort about 29 kgf. I did not take in calculation water column around the shaft so the result might be a bit worse.. (The Force on the spear on shot is the average force)

View attachment 54257
The final pressure for the later version seems to be 25 bar and as initial charge pressure is a maximum of 12 bar then the compression ratio must be 2.0. That means the gun shoots much like a dual power pneumatic gun set to low power as for a compression ratio of 2.0 that means Vb equals Vr. Vb is the volume of the barrel and Vr is the volume of the reservoir and/or any other sections behind the piston when the gun is cocked to shoot. In dual power guns low power can be much lower with a compression ration of 5, so the Santino gun shoots a bit better than that with a compression ratio of around 2.

Probably comparable to the monotube guns such as the old Nemrod "Torpedero" (or Russian "green stick" copy) in terms of compression ratio, but this gun will have modern seals and a way better trigger mechanism with a rear tied spear.

CR = initial volume divided by final volume or (Vb + Vr)/Vr = Vb/Vr + 1
RPO-2 green stick.jpg
 
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tromic

Well-Known Member
Aug 13, 2007
1,551
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Croatia
I don't believe that the average pressure of 18.5 bar = (25 + 12)/2 would be sufficient for 11 mm piston..?
It would be like Cyrano on 18,5 bar while normal operating pressure would be near 30 bar.
I agree about the muzzle port...
 
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popgun pete

popgun pete

Well-Known Member
Jul 30, 2008
3,035
590
153
Australia
Watch the videos of the gun shooting and the gun being pressurized where we see the needle on the pressure gauge moving, it moves to just under 12 bar.

The "Arbalete Pneumatico" seems to be designed for general purpose spearfishing rather than high power shooting.
 

tromic

Well-Known Member
Aug 13, 2007
1,551
149
153
Croatia
Yes it is possible for the 120 cm model the shooting range to be 5,5 m having average pressure of 18.5 bar because the working length of the piston is long - maybe 110 cm (?) and I also notice that probably 1 mm mono were used with his setup.. In that case the initial speed of the spear would be about 31 m/s and shooting on 5,5 m is possible.