Noise - when 90 fpe doesn't sound like 90 fpe

[JW652]

Check with a hydro place. If the tank brand has had issues, they will know. HPA deserves respect.

 

[MrP]

Regarding the ldc: yes, I built it myself - aluminum host, 3d printed internals. I've found a way to securely attach 3d baffles thy at can stand up to the higher pressures of this airgun. this plastic is not the most durable - I know folks sell plastic printed LDCs... It's a great medium for experimentation but in my experience it inevitably fails at higher fpe. this is pla and layers sometimes separate if hit by very high pressure. There are a variety of filament types I am aware, and epoxy coats might improve durability. 

About 7" in front of the muzzle and the remaining 6-7" is volume behind to vent into.

I'm attaching a diagram of a similar design (different outer host and this one was shorter than the aluminum ldc in the photo). The front baffle core has large vents that dump air back into the space shrouding the barrel. This isn't obvious in the sketch. The green items pictured are the clamp that goes behind the muzzle. I currently have the space surrounding the barrel packed with felt - wrapped around the barrel like a bandage.

 

[Guest]

Cool talandor. I'm partial to the Talon and its ugliness

 

[JungleShooter]

Hi

Let me explain it in this way:

Cut the barrel in 3 part like if you have 600mm barrel cut it to 3X200mm

1: You pull the trigger and your air pressure is 4000PSI:

pellet through barrel start accelerating by 4000PSI air pressure

By first 200mm of the barrel pellet achieve up to 60FPE

By second 200mm it gain 20FPE more and now it has 80FPE

By last 200mm it gain final 10FPE and now exit the barrel with 90FPE.

2: You pull the trigger with 2500PSI left in your tank.

By first 200mm of the barrel pellet achieve up to 40FPE

By second 200mm it gain 30FPE more and now it has 80FPE

By last 200mm it gain final 20FPE and now exit the barrel with 90FPE.

-------------------------------------------------------------------------------------------------------------

So here is the clue:

When you have 4000PSI in the first part you accelerate so quickly and for second and third part you accelerate less which mean less air pressure in that area. I made a sample tablefor each 1000PSI you would achieve 15FPE)&(Volume for each 200mm barrel is: ((6.35/2)^2)*3.14*200=20099=20,000)



Air pressure * Volume= (4000*20,000)+(1333*40,000)+(667*60,000)=80,000,000+53,320,000+40,200,000=173,520,000

if you want that 10 extra FPE in second part you have to fill all the first part and second part here is the table:



Air pressure * Volume= (2667*20,000)+(2000*40,000)+(1333*60,000)=53,340,000+80,000,000+79,980,000=213,320,000

Now for same energy you need 173,520,000 at high pressure and 213,320,000 at low pressure, because when pellet go further through the barrel how ever it need same amount of air pressure but more volume should be fill with that pressure.

Arash,

thank you for such a clear explanation! Very interesting!

Matthias

 

[DavyBoone]

I've been through every valve spring valve retaining nut, through hole diameter, Top Hat Gap you could imagine on the Air Force platform and the quietest and best tune comes from a heavy valve return spring and I moderate sized through hole through the valve nut.

Too much air released at the low pressure end of a shot sting with a too light V return spring May produce the same foot pounds as the high pressure end, but the excess air creates more noise and unstable bullet at the muzzle which will affect accuracy least that's been my experience.

Another thing that has helped me achieve the best tune possible is a 3-piece hammer arrangement that greatly diminishes Hammer bounce.

 

[MrP]

Thanks davyboone. Can you share that hammer setup that you use? Can anybody elaborate under what particular conditions hammer bounce is most likely? 

 

[Arash]

Hi

Let me explain it in this way:

Cut the barrel in 3 part like if you have 600mm barrel cut it to 3X200mm

1: You pull the trigger and your air pressure is 4000PSI:

pellet through barrel start accelerating by 4000PSI air pressure

By first 200mm of the barrel pellet achieve up to 60FPE

By second 200mm it gain 20FPE more and now it has 80FPE

By last 200mm it gain final 10FPE and now exit the barrel with 90FPE.

2: You pull the trigger with 2500PSI left in your tank.

By first 200mm of the barrel pellet achieve up to 40FPE

By second 200mm it gain 30FPE more and now it has 80FPE

By last 200mm it gain final 20FPE and now exit the barrel with 90FPE.

-------------------------------------------------------------------------------------------------------------

So here is the clue:

When you have 4000PSI in the first part you accelerate so quickly and for second and third part you accelerate less which mean less air pressure in that area. I made a sample tablefor each 1000PSI you would achieve 15FPE)&(Volume for each 200mm barrel is: ((6.35/2)^2)*3.14*200=20099=20,000)



Air pressure * Volume= (4000*20,000)+(1333*40,000)+(667*60,000)=80,000,000+53,320,000+40,200,000=173,520,000

if you want that 10 extra FPE in second part you have to fill all the first part and second part here is the table:



Air pressure * Volume= (2667*20,000)+(2000*40,000)+(1333*60,000)=53,340,000+80,000,000+79,980,000=213,320,000

Now for same energy you need 173,520,000 at high pressure and 213,320,000 at low pressure, because when pellet go further through the barrel how ever it need same amount of air pressure but more volume should be fill with that pressure.

Arash,

thank you for such a clear explanation! Very interesting!

Matthias

Hope that was useful.

--------------------------------------------------------------------------------------------------------

You know about Tesla Valve?

I'm thinking of how change it for silencer: my idea is like this

one baffle with some hole in it so it can let air pass through but next one has no holes. So now this extra air goes back and block the pass.

Tesla valve is this:

And my Idea is this:

 

[Guest]

I dont get it why ppl keep talking about valve return springs etc. It serves only one and one purpose only to ease filling when totally empty and thats about only reason manufacturers put them there. None regulated pcp regulates its self by far best without it and also there is more power, less airconsumption due less junk on the way to distract airflow + pressure shuts valve by far more evenly than pressure +spring. Hammerforce to knock it open is almost same bit less for none spring. Thats prettymuch first thing I do with every gun thats not running with balanced valve. 

 

[MrP]

Makes sense to me. Since you asked, it looked to me like air was wasted at low pressure and being a noob I wondered if adding a little more spring would solve that. Of course one could change hammer or hammer spring and achieve a similar result.

 

[MrP]

I'm enjoying this conversation arash.


I have indeed thought about those valves and actually tried creating one with a path for a pellet through it.


I've also been thinking about evolved designs for handling air. I mean we're sitting here fumbling with clumsy modern experiments but there are creatures on this planet that have been wrestling with the atmosphere for eons and they have some pretty good solutions. 



I printed a "biomorphic"? air stripper based loosely on lungs that tested ok. Need to get back to that design. 

 

[Guest]

Makes sense to me. Since you asked, it looked to me like air was wasted at low pressure and being a noob I wondered if adding a little more spring would solve that. Of course one could change hammer or hammer spring and achieve a similar result.

Best way to make changes is adjusting dwell and hammerforce. Valve spring generally have zero or none existing effect on how valve closes, pressure pushing it to close position is by far stronger and faster than any spring you can put in there. I assume ppl generally think increasing that spring force inside there dose something due they are actually decreasing hammerstrike force to knock valve open and therefore decreasing dwell also with increasing force required to open valve and generally this is worst, most unefficient and least practical way. If your only problem with low pressure is increased noise I would simply build alot bigger shroud to have enough volume to handle it or than just simply reduse usable pressure range. 

You can even make 257texan at 200fpe quiet by just having enough volume on shroud. Thats carbonfiber, aluminium internals total lenght 400mm, and if i remember correctly it only extends gun by 140mm. Chambers after muzzle are filled with holedpipe that is used on car mufflers and cloth and chambers around barrel are just empty space with aluminium spacers that have holes and allow airflow to go backwards, first spacer is placed almost instantly after muzzle to reflect most of air 180degree backwards. Only thing you can hear is hammer hitting and those 80+gr slugs impacting. 

 

[MrP]

Must be venting back into the shroud of the gun itself. Quiet 200fpe? I assumed only "quieter" was possible. Sounds like an excellent setup and I wish I had metalworking skills. I have a similar setup on mine but aluminum and larger volume. Works amazingly well but at 130 fpe you DEFINITELY hear air moving and more than hammer slap. Heck the "pang" of the tank itself is pretty loud. Then again, I am always right next to it when it fires so maybe it sounds quiet like yours from 20 feet away I have no idea.




Now, as for making the most of the volume you have, the Tesla diode idea sounds good. I just designed what I think is a 3d equivalent of a Tesla valve. Some features of the model exist only to make sure the form can be printed without supports / scaffolding. Here is my first draft of a Tesla valve for a 44 mm diameter outer Host and .25 cal.

the gray shape is the shape of the hole (that is the "tool" I use to hollow out the orange block on the right The purple, heart shaped piece directs the air out and around. The arches are to enable it to be made by a 3d printer. The object on the right is made by a combination of a cylinder, the gray cutout and the purple insert. I might need to add more support for that purple insert if this was going to be used at higher energy. Of course that would interfere with airflow a little bit but no big deal. This is just a rough draft I will update with the final form later... there's a lot of volume in the block that needs to be hollowed out and vented into. 

 

[Guest]

That surely is working design but I feel you are over engineering it. No matter how you handle it the main thing to achieve is to slow air down and give it as much space to expand as possible so it leaves silencer on low pressure and speed. Therefore no matter how complicated your internals are they only slow it down as much as there is space to let it expand. 

https://youtu.be/kCPwItmlPnY this is my 224cal112fpe max power airgun going off at 2900psi and surely dumping alot of air even after elvis is gone. Silencer is 170mm long 46mm diameter and 3chambers with only the last one having cloth inside. Dont need to be anything amazing as long as there is enough space and oh yes hole is only 6mm and bullets are 5.7mm

Alltho would be super interesting to see how that design works but Im sure you still need to have alot of extra expanding space. I wonder how 3D printer plastic can take that beating. I almost lost my eye last time I tried to replace aluminium endcaps with 5mm thick plastic ones.. Well the back cap blew in million parts after first shot so I assume there is alot of pressure inside. 

 

[MrP]

Over engineered for sure... I don't even have a plan to print that... was trying to follow Tesla's design in 3d as much as I could. I would definitely try to recover as much volume from the block as I could so if I were to actually print this i would hollow out those solid areas and allow air to vent into that space as well for sure.

Working with plastic prints requires a little bit of careful thinking about reinforcement. Metal housing, thick layers and 100% infill help as do epoxy coatings. You can make a plastic print that is durable but they always make me nervous.

I should have a disclaimer on all of this that playing around with different designs is not about being practical, if that was the case I'd buy one from DonnyFL or huma or Neil Clague.

So why do this? Why not buy a metal ldc?


1) connect with like minded tinkerers

2) invent a baffle that is better than others (per unit of available volume)

3) pass some of the free time I have and make use of my 3d printer 

4) challenge myself and learn 3d design so when the day comes I can do something practical 

5) make custom-fit parts that are not available in quite the same form

6) try crazy designs just see what happens. Lung shapes, gill shapes, fractals, Tesla diodes, etc.. it' is fun.

That video sounds pretty quiet! Nice I'd be more than happy with that if I understand what I'm hearing.

i'd be more than happy with that if I understand what I'm hearing. I have a metal baffle LDC that is very quiet but I'm having fun making my own custom fit items.

I have made videos of mine but of course you can never tell from those things how it sounds compared to anything else. I honestly have no idea if someone else hearing my air guns would think wow that's quiet or not. I hear the idea of mouse fart quiet and backyard friendly used but I don't know what those terms mean.

 

[Guest]

Haha yeah man I fully agree with you if its just for experiment go full crazy with designs there is no point to do it easy! In the end only thing that pushes us forward is experimenting.

Yeah videos are horrible to try to judge sounds. Quiet goes louder and loud goes quieter etc just horrible. Place where I live the only thing I need from silencer is to reduce muzzle report so much that ppl living here dont think im shooting 308win at my backyard lol. I have huma silencer also but its really bad one when it comes to high power applications. Its internals are way too weak and what comes to donnyfl etc I just dont feel like paying that money eventho donnys surely are good silencers.

Oh man I cant wait when that day arrives when we can have 3D metal printers in households. Might be years for that but it will surely come!

 

[MrP]

here it is whittled down. I think I'll add little vent holes at the top to vent into the spaces between the fins. The fins are to keep alignment as close as possible. I actually may print a stack of these after fine tuning a bit... I have something they will fit in.



Well, i had to try. Here goes!

 

[Arash]

I dont get it why ppl keep talking about valve return springs etc. It serves only one and one purpose only to ease filling when totally empty and thats about only reason manufacturers put them there. None regulated pcp regulates its self by far best without it and also there is more power, less airconsumption due less junk on the way to distract airflow + pressure shuts valve by far more evenly than pressure +spring. Hammerforce to knock it open is almost same bit less for none spring. Thats prettymuch first thing I do with every gun thats not running with balanced valve.

Hi.

Let me explain it: there are two type valve spring

1. Valve spring that a hammer hit valve while hammer spring tension is still pushing the hammer forward and none regulated (like normal PCP air rifle)

For this kind of valve spring changing the pretension is kind of useless because calculate the amount of tension is unbelievably hard.

2. Valve spring in some guns like FX and Daystate that when hammer hit the valve no spring tension pushing it (at the end of the way hammer free fly) and using regulator.

In this type of action when you compress the valve spring tension, hammer speed need's to increase (faster the valve open's) & when the valve fully opened because the more tension behind it, it will close faster.

In general by increasing the hammer weight or decrease valve spring tension, time of opening the valve will increase(by millisecond). But in real world make a good combination is difficult due to hard access to valve spring.

Makes sense to me. Since you asked, it looked to me like air was wasted at low pressure and being a noob I wondered if adding a little more spring would solve that. Of course one could change hammer or hammer spring and achieve a similar result.

If you increase valve spring tension you will increase hammer tension after that to achieve 80 to 90 FPE, it wont work like that.

I'm enjoying this conversation arash.


I have indeed thought about those valves and actually tried creating one with a path for a pellet through it.


I've also been thinking about evolved designs for handling air. I mean we're sitting here fumbling with clumsy modern experiments but there are creatures on this planet that have been wrestling with the atmosphere for eons and they have some pretty good solutions. 



I printed a "biomorphic"? air stripper based loosely on lungs that tested ok. Need to get back to that design.

Me too.

Once I used Ansys to model that, but that was to hard for me. I wanted to see what would happen if I use spring in silencer in order to dump air energy buy I couldn't model that.

Nice design, I'd love to see it in action.

Over engineered for sure... I don't even have a plan to print that... was trying to follow Tesla's design in 3d as much as I could. I would definitely try to recover as much volume from the block as I could so if I were to actually print this i would hollow out those solid areas and allow air to vent into that space as well for sure.

Working with plastic prints requires a little bit of careful thinking about reinforcement. Metal housing, thick layers and 100% infill help as do epoxy coatings. You can make a plastic print that is durable but they always make me nervous.

I should have a disclaimer on all of this that playing around with different designs is not about being practical, if that was the case I'd buy one from DonnyFL or huma or Neil Clague.

So why do this? Why not buy a metal ldc?


1) connect with like minded tinkerers

2) invent a baffle that is better than others (per unit of available volume)

3) pass some of the free time I have and make use of my 3d printer 

4) challenge myself and learn 3d design so when the day comes I can do something practical 

5) make custom-fit parts that are not available in quite the same form

6) try crazy designs just see what happens. Lung shapes, gill shapes, fractals, Tesla diodes, etc.. it' is fun.

That video sounds pretty quiet! Nice I'd be more than happy with that if I understand what I'm hearing.

i'd be more than happy with that if I understand what I'm hearing. I have a metal baffle LDC that is very quiet but I'm having fun making my own custom fit items.

I have made videos of mine but of course you can never tell from those things how it sounds compared to anything else. I honestly have no idea if someone else hearing my air guns would think wow that's quiet or not. I hear the idea of mouse fart quiet and backyard friendly used but I don't know what those terms mean.

You have lot's of motivation, I like that. I used a silencer with and with out baffles, huge differences. when air come out at the end of the barrel it carry's lot's of energy, baffle will dump that energy by expanding it. Silencer volume is the area that this air expand and baffles are the key to good expansion.

 

[knifemaker]

The tesla system is already being done and very extensively tested. Here---Near the bottom. Lots of test! 

https://www.silentthunderordnance.com/blog

 

[knifemaker]

And Here-



View attachment SILENCER SPECS TABLE. 17. 2020-10. TABLE.1601784364.pdf

 

[DavyBoone]

Thanks davyboone. Can you share that hammer setup that you use? Can anybody elaborate under what particular conditions hammer bounce is most likely?

I'll pull the hammer Arrangement sometime this week and take you a pic.

You want the breach very lightly resting on the valve head /top hat. Too much preload on the spring will cause more hammer bounce, waste a lot of hair and mess with your accuracy.