Standard 22 Moderator 1/2 UNF x 20

[OldCrow]

The current thingiverse upload has the 177 now, and all the STLs all look correct.  Thanks again!

Thank you sir!
Here's another.
https://www.thingiverse.com/thing:6992213

[OldCrow]

Just added the "BOA" to the catalogue up at thingiverse.

It is a two baffle "fat" can 100mm x 60mm about 283cc .  The design was sort of imspired by the "cans" that Airforce puts on the Talon P rifles.  Very big, fat and ugly but quiet in a short package.

https://www.thingiverse.com/thing:6992911

I uploaded several non-AG related models up today as well.  If anyone is interested in Mikrotik routers they might find a useful case up there.

[OldCrow]

MAMBA  150mm x 50mm

https://www.thingiverse.com/thing:6994218

This is the last moderator I'll be uploading for this series.  They cover basically anything you want in an AG moderator unless your shooting big bore airguns.  Everyone of them prints with 1/2 x 20 unf threads.

Ill be updating some of the older stls and 3mf files to clean up some issues with fonts which look great when printed on a resin printer but not so much when printed on an FDM printer.

I'll be working on cleaning up the documentation and notes over the next month and I expect this project will be complete by 1 May

Enjoy.

[OldCrow]

All the moderators I've put up on Thingiverse now include files to do both M10 x 1 printed threads and 1/2 x 20 UNF.

There will be some cosmetic changes to the pages there.  The 3mf files will not change again.  I made changes suggested by @subscriber and @bduardes

[naptemp]

Great moderators.
I downloaded all of them and will print a few.

How well do 2 or 3 baffles moderators work compared to 4+ baffles, assuming the same volume?

[OldCrow]

Great moderators.
I downloaded all of them and will print a few.

How well do 2 or 3 baffles moderators work compared to 4+ baffles, assuming the same volume?

That's a hard question.  I wish I could tell you an answer which would always hold true.  The Ember has always been reported as "impressively quiet for it's size".  I personally know the "standard" model is quieter on my rifles but other's say that isn't true for them.

I do have some "new" information for those who are following this thread though.  See next post.

[OldCrow]

OK guys regarding these Tessla baffles.  Couple years ago I realized that I could compute the "cutoff velocity" for the valves.  I never did it in the code but I often did it on spread sheets.  I've been modifying the code and decided to incorporate that calculation in the code so that I could monitor it when I was tweaking designs.

Why is this important?  The cutoff velocity is the velocity BELOW which the Mach 1 shock wave emanating from the muzzle of the rifle catches the pellet as it is passing through the first cone.  Any velocity below that will encounter enormous turbulence as the back pressure ramps up.  Any velocity above that will clear the first cone and be flying in "clean" air as it transits the remainder of the moderator (unless the shock wave catches up but that is a different problem).  My calculations are probably accurate to about +/-5% on that number.

This image file has a list of the dimensions of every moderator I've posted on thingiverse and more importantly it shows the cutoff velocities for each moderator in each caliber.  If you want to check my work you can build one of the crazy designs (for example the Spooky 22) or you can simply crank your PCP down into the cutoff range of one of the more sensible designs (for example the Ember or Phantom 22).

Over the next couple of weeks I am going to either remove the models which are obviously going to destabilize pellets (the ones in red) or rework them to get that velocity where I want it.  I like it to run around 750 for hunting rifles and in the mid 800's for target purposes.  Anyway... yeah.

I figured if I gave you a heads up you would avoid spending resin or filament working on the ones which I probably should have kept in house.

[Robert 5mm]

Mike,

For the Standard model.

Does the Red Critical velocity change with caliber of barrel versus caliber of the suppressor.

Example : use the .22 Standard on a .177 barrel or use a .25 Standard on a .22 barrel ?

[OldCrow]

Mike,

For the Standard model.

Does the Red Critical velocity change with caliber of barrel versus caliber of the suppressor.

Example : use the .22 Standard on a .177 barrel or use a .25 Standard on a .22 barrel ?

The cutoff velocity changes when the physical geometry of the moderator changes and when the physical length of the pellet changes.  Since the length isn't known exactly the calculation uses a heuristic of 1.5 times the caliber for that calculation.   Usually a smaller caliber pellet is going to be a bit shorter than the one modeled in the calculation for a larger caliber.  That would decrease the cutoff velocity.  A .22 pellet in a .25 caliber moderator would be operating with a slightly more favorable cutoff velocity, perhaps 5 or 10 percent.  The same would be true for a .177 in a .22 caliber.

HTH
Mike

[naptemp]

Great moderators.
I downloaded all of them and will print a few.

How well do 2 or 3 baffles moderators work compared to 4+ baffles, assuming the same volume?

That's a hard question.  I wish I could tell you an answer which would always hold true.  The Ember has always been reported as "impressively quiet for it's size".  I personally know the "standard" model is quieter on my rifles but other's say that isn't true for them.

I do have some "new" information for those who are following this thread though.  See next post.

I will print the Wraith today.
It seems to be the largest 3 bafflle moderator (excluding the Archangel).

Do you have a single document/image showing the specs for the moderators (dimensions, number of baffles, etc)?

[OldCrow]

Great moderators.
I downloaded all of them and will print a few.

How well do 2 or 3 baffles moderators work compared to 4+ baffles, assuming the same volume?

That's a hard question.  I wish I could tell you an answer which would always hold true.  The Ember has always been reported as "impressively quiet for it's size".  I personally know the "standard" model is quieter on my rifles but other's say that isn't true for them.

I do have some "new" information for those who are following this thread though.  See next post.

I will print the Wraith today.
It seems to be the largest 3 bafflle moderator (excluding the Archangel).

Do you have a single document/image showing the specs for the moderators (dimensions, number of baffles, etc)?

   

[WhatUPSbox?]

What triggers the Mach 1 condition?

[OldCrow]

What triggers the Mach 1 condition?

The velocity of sound at standard temp and pressure. 

I am trying to calculate the fastest possible arrival of interference at the bottom of the top cone in the baffle.  Once I have that I can calculate the minimum velocity that will allow the pellet to clear that intersection before it happens.  That calculation is dependent on the  exact geometry of the moderator.

What do you think?

[WhatUPSbox?]

I guess my question really was, for a subsonic pellet, in your calculation, when does the flow achieve sonic condition and create a shock wave? You must use that time delay to start the race to the first baffle.

[OldCrow]

I guess my question really was, for a subsonic pellet, in your calculation, when does the flow achieve sonic condition and create a shock wave? You must use that time delay to start the race to the first baffle.

That is an interesting question.  If the pellet never achieves mach then the first instance of the "shock" wave being created is at the muzzle during "uncorking".  The pressure increase itself has no doubt started within the moderator body as the velocity of the pellet ramps up during barrel transit.  I have not tried to model that part of the problem.

The "shock wave" I am discussing here is really a pressure wave which can not travel slower than (or faster than) Mach 1.  It is actually an audio pulse.  There is no supersonic shock wave associated with airguns until the pellet actually exits the barrel at some velocity above the speed of sound.

However the sound pressure which the "uncorking" event generates DOES travel at the speed of sound.  Hence Mach 1.

So we are working with two different velocities here, yes.  The velocity of the pellet and the velocity of the sound pulse created by the "muzzle blast".

I am using the moment the crown of the pellet exits the barrel as the start time for my calculation.  The model is not perfect.  There is no such thing as a perfect model.

[naptemp]

I guess my question really was, for a subsonic pellet, in your calculation, when does the flow achieve sonic condition and create a shock wave? You must use that time delay to start the race to the first baffle.

That is an interesting question.  If the pellet never achieves mach then the first instance of the "shock" wave being created is at the muzzle during "uncorking".  The pressure increase itself has no doubt started within the moderator body as the velocity of the pellet ramps up during barrel transit.  I have not tried to model that part of the problem.

The "shock wave" I am discussing here is really a pressure wave which can not travel slower than (or faster than) Mach 1.  It is actually an audio pulse.  There is no supersonic shock wave associated with airguns until the pellet actually exits the barrel at some velocity above the speed of sound.

However the sound pressure which the "uncorking" event generates DOES travel at the speed of sound.  Hence Mach 1.

So we are working with two different velocities here, yes.  The velocity of the pellet and the velocity of the sound pulse created by the "muzzle blast".

I am using the moment the crown of the pellet exits the barrel as the start time for my calculation.  The model is not perfect.  There is no such thing as a perfect model.

I printed the Wraith in .177 and installed it on a 14-15 FPE .177 PCP.
The Wraith is a little quieter than the other significantly larger moderator.
Definitely works well for its size.

[OldCrow]

I printed the Wraith in .177 and installed it on a 14-15 FPE .177 PCP.
The Wraith is a little quieter than the other significantly larger moderator.
Definitely works well for its size.

Test for accuracy.  You might be disappointed.  I hope not.

[naptemp]

I printed the Wraith in .177 and installed it on a 14-15 FPE .177 PCP.
The Wraith is a little quieter than the other significantly larger moderator.
Definitely works well for its size.

Test for accuracy.  You might be disappointed.  I hope not.

The accuracy with the .177 Wraith is fine.

I will print the .22 version of the Archangel over night.

[naptemp]

I put the Archangel on a .22 28FPE PCP.

It works but for its size I expect better.
After all it's ticker than the air bottle.

No more tick and short moderators for me.
The longer moderators work much better.

[naptemp]

So far, I printed two .177 Wraith moderators.
They work well in lower power.

The photo shows the .177 Wraith and Kent's moderator (which I have printed many times).

I tried both on three 6-9 FPE .177 PCP pistols.
The Wraith is a little more quiet but it also has more volume.

So, Tesla valve or not, volume and length seem to matter more.

Also, the short moderators are louder than longer ones.