About what psi is behind the pellet of a break barrel when it starts to move?

[Motorhead]

If the springer are more EFFICIENT, why the companies are not developing different geometry or ways to canceling the movement of the shot cycle??

Daystate is supposed to have a 2 opposed piston springer later this year...

I would love a springer shooting as smooth as a PCP with the same power levels..

As a PREPPER GUN, it would sell like CUPCAKES...

Increased COMPLEXITY = higher Cost along with greater Weight.
This is nothing new and recoil damped or self canceling cyclic has been done before and died a quick death when SSP came to be which nearly died when PCP replaced them.
While some of each type still exist ... the modern PCP and its variation's are the new normal.

Just sayin ...

Scott
 

[Madd Hatter]

Replace the steel spring and steel piston with one from Titanium and it should reduce the recoil effect but how much who knows.

[Stinger177]

If the springer are more EFFICIENT, why the companies are not developing different geometry or ways to canceling the movement of the shot cycle??

Daystate is supposed to have a 2 opposed piston springer later this year...

I would love a springer shooting as smooth as a PCP with the same power levels..

As a PREPPER GUN, it would sell like CUPCAKES...

There were opposing force systems in the past. Don't know why they fell out of favor. Perhaps someone in here can explain why.

Do a Google search for GISS system airguns. 

[grand-galop]

As i follow  the discussion, the calculations  of pressure  have  been  done  with average power rifles..  The compression  chamber diameter is expending the power when we look at Hatsan..  I dont  know any brand that use 40mm piston , but would like to see pressures and power levels  obtain with 160bar piston...

[Hoosier Daddy]

If the springer are more EFFICIENT, why the companies are not developing different geometry or ways to canceling the movement of the shot cycle??

Daystate is supposed to have a 2 opposed piston springer later this year...

I would love a springer shooting as smooth as a PCP with the same power levels..

As a PREPPER GUN, it would sell like CUPCAKES...

There were opposing force systems in the past. Don't know why they fell out of favor. Perhaps someone in here can explain why.

Do a Google search for GISS system airguns. 

My vintage FWB 300S uses opposed springs, counter wound coils, on a single piston.
 They were used ion the Olympics back in the late '70s early '80s.
I am told the SSP is what did them in.

[subscriber]

According to Hector Medina, springers can reach peak air pressures of 3000 PSI:  https://www.ctcustomairguns.com/hectors-airgun-blog/at-the-moment-of-firing-and-fit-of-pellet-to-the-rifling  (scroll about 45% down the page)

If Cardew's 8 ft.lb popgun produced a peak air pressure of 1500 PSI, then 3000 PSI for something such as a 22 ft.lb Diana 350 certainly sounds feasible.

[Tom Tucker]

Another important point as I re-read the subject line to this thread is that the pellet starts to move before peak pressure is achieved.  A tighter-fitting, thicker-skirted pellet will tend to stay put a little longer.  A heavier pellet will start off more slowly.  I read an article while ago where a bunch of .177 caliber pellets were tested... in fact, I think I saved a graphic from it.  In the article, the same gun preferred a loose-fitting JSB pellet in .177 and a tight-fitting RWS in .22.

[George Schmermund]

Stan and I spent some time developing ideas that may be of use to anyone interested in pellet release times and pressures. Our efforts were in the realm of CO2 pistol measurements, but these methods would easily be transferable to any airgun.

https://www.gatewaytoairguns.org/GTA/index.php?topic=137566.300

[rsterne]

Thanks for that, George.... I keep promising myself that when I get some time I am going to study that thread in detail.... There is so much great info there, it deserves more than a casual read.... 

Unfortunately, I still haven't found the time.... but I will.... 

Bob

[subscriber]

I am still reading George's thread, and it is full of useful nuggets, including the question of pressure curves down the barrel.

[young_skywalker]

If the springer are more EFFICIENT, why the companies are not developing different geometry or ways to canceling the movement of the shot cycle??

Because they are relatively expensive to manufacture - and when maintenance is required, things can quickly go pear shaped. Go set aside $5k and start looking for a Whiscombe if you want PCP power out of a springer.

Daystate is supposed to have a 2 opposed piston springer later this year...

Would love to see info on the Daystate you mention.

As a PREPPER GUN, it would sell like CUPCAKES...

I think it's all about the cost...how many cupcakes is the market?

[grand-galop]

Please!! Dont tell me cost is an issue...
Since pcp's have double the material involved in their duild and can be sold at 300$ ,there is no excuses  for not getting into developping    the break barrel  and still making profit..
I think they can make the power levels on par with pcp's and be SHOOTABLE with a controlled recoil.

[subscriber]

Please!! Dont tell me cost is an issue...
Since pcp's have double the material involved...

It is not the material cost.  It is the part cost. 

How much does a steak cost at a restaurant?  How much does a steak cost when still attached to the cow?

[young_skywalker]

How much does a steak cost at a restaurant?  How much does a steak cost when still attached to the cow?

I really like this comment for it's perspective.

[grand-galop]

Please!! Dont tell me cost is an issue...
Since pcp's have double the material involved...

It is not the material cost.  It is the part cost. 

How much does a steak cost at a restaurant?  How much does a steak cost when still attached to the cow?

You are that kind of people that will accept to run with sqared tire..
 

[rsterne]

Please.... exchanging opinions is fine.... let's leave the insults at the door.... They are not welcome in the Workshop....

Bob

[mobilehomer]

Bob, I don't know if anyone has done this, I would like to see the results if so. Why not put pressure transducers on the barrel block? One passage into the transfer port. One into the compression chamber. And one into the chamber. This would give real world figure for one example, I know, but done with several different calibers it should be usable data to extrapolate approximate values for others.

[rsterne]

Should work....

Bob

[grand-galop]

Is it possible to transfer the calculation map they use in the internal combustion engine to calculate the approximate pressure before the pellet start to move??  I think the shot cycle of the 15 flb rifle is equivalent to the duration that occurs at 2400 rpm in a combustion engine..  Not  including the detonation pressure would be a clever tool since they use bore and stroke ..

[subscriber]

Is it possible to transfer the calculation map they use in the internal combustion engine to calculate the approximate pressure before the pellet start to move?? 

You can calculate the minimum pressure required to start the pellet moving.  If you took a narrow probe and pushed on the pellet until it "popped" loose from the breech cone, that force can be calculated to pressure, based on the area of the pellet.  What makes the calculation after that tricky is that the pellet also has inertia.  The inertia will act to try and keep the pellet in place, and raise the actual peak pressure.

There is an airgun internal ballistics paper that has been linked on this forum a number of times.  It both calculates and measures spring air rifle performance.  It is well worth the read; except I can't attach the PDF because it is too large.  PM me you email address and I will send it to you.