Thought I would start a bit of a thread and compilation about the size of the air transfers in pneumatic spearguns.
There has always been talk about how some guns' transfer ports in the bulkhead throttle the airflow too much and limit the ultimate power of the gun. To the point where - supposedly - a popular mod amongst the mediterranean spearos was to yank out the bulkhead as soon as you bought your gun and also sometimes open up the transfers at the rear of the barrel.
For now, I don't have any answers, I will just share some measurements as I do them or find them in my "archives". (I am still without most of my speargun parts as I am now based in the Philippines but a lot of my stuff is still in storage in China).
I will be focusing on 13mm guns but the real problem is, I have no way to model how much you can reduce any orifice the air has to pass through before it starts hurting the gun's performance. Also, does the shape of the ports matter? Is the flow laminar or turbulent and to which extent does that matter. There are so many things we don't actually know here but maybe someday we will have an expert in fluid dynamics here who can chime in
But air, of course, is extremely malleable in lack of a better word, so it might be a fair assumption that not all openings have to match the 133mm² cross area of a 13mm piston. But how much smaller can we go...?
Anyhow, let's get started in the next post with the PredaThor which is one of the guns I do have on hand.
There has always been talk about how some guns' transfer ports in the bulkhead throttle the airflow too much and limit the ultimate power of the gun. To the point where - supposedly - a popular mod amongst the mediterranean spearos was to yank out the bulkhead as soon as you bought your gun and also sometimes open up the transfers at the rear of the barrel.
For now, I don't have any answers, I will just share some measurements as I do them or find them in my "archives". (I am still without most of my speargun parts as I am now based in the Philippines but a lot of my stuff is still in storage in China).
I will be focusing on 13mm guns but the real problem is, I have no way to model how much you can reduce any orifice the air has to pass through before it starts hurting the gun's performance. Also, does the shape of the ports matter? Is the flow laminar or turbulent and to which extent does that matter. There are so many things we don't actually know here but maybe someday we will have an expert in fluid dynamics here who can chime in
But air, of course, is extremely malleable in lack of a better word, so it might be a fair assumption that not all openings have to match the 133mm² cross area of a 13mm piston. But how much smaller can we go...?
Anyhow, let's get started in the next post with the PredaThor which is one of the guns I do have on hand.
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