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Are we going about this correctly?? strictly for the tech heads! (warning long read)

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#42 · (Edited)
I just tried them(My cylinder heads) again, and now the long reducer performs 32fps better(Using 0.40g).
The only difference I can tell is the long reducer is "crownd" better.

My current piston weighs 45g, 0.40g bb, and I use a M160 spring.

Edit: I just made a new reducer, this time it's filling the nozzle up completely.
The new reducer results in a output increase of about 26fps.
Compared to the 6mm reducer, it's a increase of about 58fps(Or 82fps using 0.20g).
 
Discussion starter · #44 ·
BuMS said:
I just tried them(My cylinder heads) again, and now the long reducer performs 32fps better(Using 0.40g).
The only difference I can tell is the long reducer is "crownd" better.

My current piston weighs 45g, 0.40g bb, and I use a M160 spring.

Edit: I just made a new reducer, this time it's filling the nozzle up completely.
The new reducer results in a output increase of about 26fps.
Compared to the 6mm reducer, it's a increase of about 58fps(Or 82fps using 0.20g).
Click to expand...
Good job, well done :tup:

So your tests show a long(full length) port helps increase fps, possibly due to smoothing the air flow, I have read somewhere that in air rifles a venturi did nothing to speed up the air, and added turbulence reducing its ability to provide stable power to the pellet.

The one thing that we haven't mentioned much in all this is the variable weight of BB that could be used, along side what size port to use to best effect

Would a narrow port better suit lighter ammo?? (I personally prefer .28s as most sites I play have a power cap at 450fps or lower, plus I like to see where my BB is going to be able to make ajustments as its normally quite windy aswell)

Or would a standardised port size do for all ammo and we just vary the piston weight to suit required compression pressure???

So many questions, not enough answers & not enough time available to test out the theories :lame:
 
#45 ·
Another way of making BB Retention is to make another nub exactly opposite in the hopup on the bottom. Make it adjustable. So a nub on the top and bottom.
I done this once before on an AEG (M4) but it did not work very well (inaccurate) but if someone is keen they should investigate as I did not investigate enough. (Should have done it to the VSR)
You would only apply a little hop on the bottom nub and more on the top nub. This would mean that the bb will hold for longer but grip onto the top nub more to create the backspin the bb needs.
Anyway, it's an idea that may work for a Sniper Rifle.
 
Discussion starter · #46 ·
1tonne said:
Another way of making BB Retention is to make another nub exactly opposite in the hopup on the bottom. Make it adjustable. So a nub on the top and bottom.
I done this once before on an AEG (M4) but it did not work very well (inaccurate) but if someone is keen they should investigate as I did not investigate enough. (Should have done it to the VSR)
You would only apply a little hop on the bottom nub and more on the top nub. This would mean that the bb will hold for longer but grip onto the top nub more to create the backspin the bb needs.
Anyway, it's an idea that may work for a Sniper Rifle.
Click to expand...
That could work, but positioning would be critical or cancellation will occur.

I'd of said if you put the bottom adjuster directly below the BB as it sat infront of the hop up nub that would probably be best, but then as has already been brought up, those miracle barrels would be close to achieving the same thing.
 
#47 ·
vindicareassassin said:
That could work, but positioning would be critical or cancellation will occur.

I'd of said if you put the bottom adjuster directly below the BB as it sat infront of the hop up nub that would probably be best, but then as has already been brought up, those miracle barrels would be close to achieving the same thing.
Click to expand...
If you put the bottom adjuster directly below the bb as it sat in front of the top hopup nub then you adjust the bottom nub upwards, it would pretty have the same reaction as if you were to push the top nub down as the bb would get restricted by the top nub. So it would be pretty much the same as a normal hopup but being adjusted from the bottom.

Although instead of putting them vertically above each other the bottom one could be back maybe half a millimetre. This would then make sure the top nub was to last to contact.
 
#48 ·
So wouldn't having a smaller diameter exit port slow down the piston? Which is the opposite of what we would want.

1tonne, I think that setup would work perfectly if you have a longer top contact patch and a really short bottom nub.
 
#49 ·
TheHunter said:
1tonne, I think that setup would work perfectly if you have a longer top contact patch and a really short bottom nub.
Click to expand...
That may just be the trick. Could even have a long nub on the top and a short on the bottom
 
Discussion starter · #50 ·
TheHunter said:
So wouldn't having a smaller diameter exit port slow down the piston? Which is the opposite of what we would want.

1tonne, I think that setup would work perfectly if you have a longer top contact patch and a really short bottom nub.
Click to expand...
Go and re-read ALL of thread, it is all fully explained
 
#53 ·
That is where the double nub thing would work.
 
#54 ·
There are to many counter productive parts in this idea so far.

I believe the double nub needs to be at the top of the todo list on modding and we need to find a very efficient way to make a high pressure spring system distribute air very quickly much like a gas system.

I think Vindi has a good start but needs to be reconfigured a little.
 
#55 ·
I find the idea of bb retention a bit misguided.
The hopup can create so much force, that the bb won't shoot past.
That alone, should create more retention, then the ideas so far.

A better option, would be to use a longer hop patch, so the max hop retention(Where the bb still can be fired) can be achieved for a longer time.
That would leave us in ER-hop territory.
 
#56 ·
BuMS said:
I find the idea of bb retention a bit misguided.
The hopup can create so much force, that the bb won't shoot past.
That alone, should create more retention, then the ideas so far.

A better option, would be to use a longer hop patch, so the max hop retention(Where the bb still can be fired) can be achieved for a longer time.
That would leave us in ER-hop territory.
Click to expand...
Using just a normal hopup with only one nub will create bb retention and can eventually stop the bb from coming out. The problem is that all the pressure is coming from just one nub at the top and if you apply too much on the top nub you will create more back pressure but also you will create more hopup and so the bb will fly sky high. Since we are wanting the bb not to go skyward we need to even it out from the bottom (But still have hopup) and this is where the bottom nub comes into play.
 
#57 ·
I'm not sure if I even think the high pressure/heavy weight piston stuff is necessary. As long as the bb comes out of the barrel consistently at the same fps with consistant backspin. What does it matter if the piston hasn't decompressed all the way? Could someone clear this up a bit for me?
 
#58 ·
I guess I will give this a shot. My understanding is that this is not about consistent fps, it is about consistent hop. The point of reducing initial air release is so the bb does not pass the hopup as soon as the piston begins its cycle forward. This can be counteract by increasing the hop, but the way I see it, the more aggressive hop you apply, the less stable the bb. So by allowing the bb to remain in the hop while more pressure is build up, less hop is required resulting in smoother, more effective and consistent backline. This would explain the wind resistance as the smoother the hop, the more stable the bb will be and the longer the backspin will last. I don't know if this helps but that is my shot at it.

Sent from my SCH-I535 using Tapatalk
 
#59 ·
1tonne said:
Using just a normal hopup with only one nub will create bb retention and can eventually stop the bb from coming out. The problem is that all the pressure is coming from just one nub at the top and if you apply too much on the top nub you will create more back pressure but also you will create more hopup and so the bb will fly sky high. Since we are wanting the bb not to go skyward we need to even it out from the bottom (But still have hopup) and this is where the bottom nub comes into play.
Click to expand...
lol I was way too tired when I wrote that.
So instead we are looking at a adjustable miracle barrel.
Image
 
#60 ·
Sneaktheif said:
I guess I will give this a shot. My understanding is that this is not about consistent fps, it is about consistent hop. The point of reducing initial air release is so the bb does not pass the hopup as soon as the piston begins its cycle forward. This can be counteract by increasing the hop, but the way I see it, the more aggressive hop you apply, the less stable the bb. So by allowing the bb to remain in the hop while more pressure is build up, less hop is required resulting in smoother, more effective and consistent backline. This would explain the wind resistance as the smoother the hop, the more stable the bb will be and the longer the backspin will last. I don't know if this helps but that is my shot at it.

Sent from my SCH-I535 using Tapatalk
Click to expand...
After reading your post and thinking some more, i think the purpose of this is to accelerate the bb as fast as possible to the fps that the gun is set for by the time it exits the barrel. To reduce bb time in the barrel and to allow you to apply less hop. But can a bb handle the acceleration without going out of control? This works on airguns because they shoot a pellet that doesn't have backspin. So we need to not get airsoft guns too confused with airguns.

I might be stated some things vindi already said, but i dont remember and dont feel like going back and checking. And i dont think it was posted as straight forward. :cheers:
 
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