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Old 12-18-2016, 05:03 AM   #16
Diving Gecko
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Re: Inalex "Alpha C1" pneumatic speargun

Quote:
Originally Posted by popgun pete View Post
Don't confuse the manufacturer's indicative range of loading effort with that required to load his gun at 30 Bar, those figures are for the gun at minimum pressure, not maximum or even anywhere near it. You seem to want to create a reputation here, just make sure that it is not the wrong one.
[...]
Pete, did you even read what you yourself had posted and I quoted before you insulted me?
This is what you posted:
"Maximum Operating Pressure: 30 Bar
Usual Operating Pressure: 18 - 20 Bar
Loading Effort: 22 - 25 kgf for the above air pressures" (the bold is my highlighting)

So, no - it doesn't say loading effort for "low end charge pressures", it says loading effort for 22-25bar. There is no other way to read this.

The data you quoted or the way you quoted it was erroneous and maybe that never occurred to you. It didn't actually to me as I have too much respect for your math skills to think that could ever happen, so I asked if there was something in the design that could explain this discrepancy - and your reply was disrespectful. Simple as that.
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Old 12-18-2016, 03:20 PM   #17
popgun pete
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Re: Inalex "Alpha C1" pneumatic speargun

Translation 2014/11/04

As for disrespect, ask "Impaler Spearguns" and consider what happened there. I had a word with the moderator and on balance your comments were allowed to stand after we had agreed to it, but they would otherwise have been rubbed out.

Embarrassed you may be, but insulted, no.
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Old 12-19-2016, 03:22 PM   #18
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Re: Inalex "Alpha C1" pneumatic speargun

"In Soviet-era Russia pneumatic speargun operating manuals had to be more precise and honest, although the buyer still had to think about what the figures actually meant. Here is an example for a "Prizm", or an RPB-1M."

Just to elaborate on the "think" comment above I will discuss what the numbers mean in that specification table for the "Prizm" or the RPB-1M. The calculations are easy because the Soviets included numbers in the corresponding size units. The force on a piston is obtained by multiplying the pressure in the gun by the cross-sectional area of the piston. (Note that a square centimetre is 0.0001 square metre or 1 x 10^-4).

Thus for charge pressure P at 147 x 10^4 N/m^2 and a piston cross section A of 1.5 cm^2 or 0.00015 m^2 we get a force value F = P x A = 147 x 1.5 = 220.5 N, (note that N is the force expressed in Newton as the measurement unit). The 10^4 cancels out with the 0.0001 or 10^-4. The table gives a range of force values between 98.1 and 225.63 Newtons which is equivalent to a range of 10 to 22.3 kgf, so the numbers agree with the P x A calculation.

What was not revealed in the table was what level of initial chamber pressure was used, i.e. what pressure had the gun been pumped up to in the first place. Now I calculated the compression ratio of the RPB-1M gun at 2.0, which is pretty high for a pneumatic speargun. Hence that means initial charge pressure must be 147/2 or 73.5 x 10^4 N/m^2 or 15/2 or 7.5 kg/cm^2 which is relatively low, about 7.5 Bar. To obtain initial charge pressure we have divided the final, or cocked pressure, by the compression ratio.

So what if we had ignored the RPB-1M instruction book and using the handpump then squeezed 147 x 10^4 N/m^2 or about 15 kg/cm^2 into the gun as the initial pressure. That would mean that charged to shoot pressure would be 30 kg/cm^2 and final force application to obtain latch would then be 441 Newtons!! A Newton is a kgf x 9.8 as it is an absolute force unit in the SI system, therefore 441 Newton is 45 kgf. or close to 100 pounds of force. The table lists a caution with maximum permissible chamber pressure being 196 x 10^4 N/m^2 which limits the force to 196 x 1.5 or 294 N which is about 30 kgf or 66 pounds of force. Any more pressure and there is a real prospect of bending the spear which is necked down to provide a catch position for the sear tooth to engage which effectively weakens the 9 mm diameter RPB-1M's shaft.
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Old 12-19-2016, 06:22 PM   #19
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Re: Inalex "Alpha C1" pneumatic speargun

The reason I have added the "Prizm" or RPB-1M to this discussion is that it has the same diameter bore as the "Alpha C1" and the calculations will therefore be the same. The difference is the "Alpha C1" has a big air tank of a large OD and a much lower compression ratio than the "Prizm" and it also has a much stronger spear because there are no weakening grooves in its spear. To muzzle load any pneumatic gun the effort is not always revealed in the figures as you can have "stiction" added to the force being provided by the gun's internal pressure. At the start of a hunting session I have seen the spear bow on my "Sten" as I apply the first muzzle loading effort of the day, the piston apparently jammed tight into the muzzle, then it suddenly moves down the barrel. On subsequent shots this "refuses to budge" opposition by the piston has completely disappeared, but unfortunately the final latch effort stays the same. As to what is the loading effort and how to describe it, well you never get an answer unless it is the "latching effort to cock the gun" at final shooting pressure. Gun manufacturers could make it easy to calculate if they gave you their gun's compression ratio, but they rarely do.

I don't know what the compression ratio is for the "Alpha C1", but then I never asked. As for the quoted loading effort I assume that it is an average of the push required on the loading bar, somewhere between the initial effort and the final latching effort as the spear is driven down into the gun. Because the "Alpha C1" uses a releasing valve there is no sear catch as such, hence the shaft can be pushed in a number of times as you work it, and the sliding piston, to travel right back to the rear end of the inner barrel.

Last edited by popgun pete; 12-19-2016 at 06:32 PM.
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Old 12-20-2016, 01:41 AM   #20
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Re: Inalex "Alpha C1" pneumatic speargun

The advantage of a 14 mm diameter inner barrel gun is only 16% compared to a 13 mm diameter inner barrel gun as 14^2/13^2 equals 196/169 which is 1.16. In the sixties and seventies the majority of pneumatic spearguns were 13 mm or 0.5" as that was the "standard", but more expensive guns such as the GSD models had 14 mm diameter inner barrels using their increased power as a selling point. A similar calculation for 13 mm and 11 mm inner barrels gives the answer as 13^2/11^2 equals 169/121 which is 1.40 or 40% improvement. Not surprisingly divers find those 11 mm diameter inner barrel guns easy to load, especially if they are stepping down from 13 mm guns.

Last edited by popgun pete; 01-04-2017 at 02:53 PM. Reason: spearguns plural
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Old 12-20-2016, 12:48 PM   #21
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Re: Inalex "Alpha C1" pneumatic speargun

~~ I personally, am glad that both you guys are here. Cheers, K.
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Old 12-29-2016, 04:38 PM   #22
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Re: Inalex "Alpha C1" pneumatic speargun

More photos of inventor Alex with his "Alpha C1" spearguns. The "Alpha C1" has sufficient gun power to drive a trident head at high velocity and take out several victims with a single shot. Also the trident can punch through a larger specimen as seen in the next photo.
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Old 01-11-2017, 03:52 PM   #23
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Re: Inalex "Alpha C1" pneumatic speargun

Here is a video of the "Alpha C1" shooting over a long distance underwater. While it can slam its shaft right through the target a contemporary band gun can barely make the distance to the target. Gun power on display here as the "Alpha C1" is virtually a straight line shooter over this distance.
http://vk.com/video224496305_171564282?fb_ref=Default
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