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A scientific look into the dynamics of the shot cycle of three spring-piston airguns


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(@hector-j-medina-g)
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Not an April's Fools joke.

This will be a NINE part series.

We use three of the best recoiling spring-piston rifles ever made.

We will publish one part every two weeks.

https://www.ctcustomairguns.com/hectors-airgun-blog/shot-cycle-dynamics-in-3-spring-piston-airguns-preface

Hope you all enjoy!

 

 

HM


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DavidEnoch
(@davidenoch)
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Hector, I look forward to reading about this research in your blog.  I wish you could test multiple transfer port sizes in one gun.  I think that would be insightful.  We need some new research to update what Cardew did years ago.

David Enoch


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(@hector-j-medina-g)
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@davidenoch

Thanks, David.

Sadly, that is something that cannot be done easily. AND it has been done. What we will show is that the TP geometry is NOT THAT important if other factors are taken into account.

The Cardews' work was exceptional for its time, but it is, now, dated. AND, more importantly IMHO, is that we will provide anyone that's reasonably handy with the tools and knowledge to create a machine to measure the vibrations in THEIR rifles

This will be an experiment in "Crowd-researching" that HOPEFULLy, will de-bunk some "theories" ("truths"?) that have been accepted and prevalent since the old days and that have hampered the real development of the spring-piston airgun.

 

So, stay tuned . . .    😉


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(@pruitt)
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This is great information! thanks for sharing.


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DavidEnoch
(@davidenoch)
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Hector,

I look forward to the research.  I know Tom Gaylord played with a set of changeable transfer ports at one time.  I don't think he had a mechanism to measure movement though.

One thing that has puzzled me is that occasionally I come across a gun that jumps vertically when fired.  I don't think it is a rotational movement but that is the only thing I can think of that would cause a springer to bounce vertically.

David Enoch


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(@hector-j-medina-g)
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David;

Most modern spring-piston airguns have a "jump" or "upwards flip" as the Brits call it.

It obeys the fact that the pistons are  moving forwad, the rifle is moving backwards,  but it is supported by the shoulder at a point where that reaction is ABOVE and offset vertically, so that the gun seems to "jump".

If you have ever shot a Baikal IZH 60 or the copy, or the SPA SLR900, you will note the real absence of this "flip". That is because the piston runs in the stock, from the buttpad to the pistol grip. SO the support point is ABOVE the reaction of the gun.

To the shooter it is a flip, but in reality is a rotation around a point that is relatively far away from the origin of the reaction.

😉

Keep well and shoot straight!

 

 

 

 

HM


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straitflite
(@straitflite)
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Posted by: @hector-j-medina-g

What we will show is that the TP geometry is NOT THAT important if other factors are taken into account.

The Cardews' work was exceptional for its time, but it is, now, dated

I have read Cardews cover to cover and I believe the only thing that is dated are the tools and technology. Same could be said for Einstein's theory of relativity; Given proper context. But dated? That is an EXTREMELY strong statement -given your own context. Same for TP geometry. Are we to believe that Bernoulli's principle no longer holds water as well?

Hector, you are more knowledgeable than I in airgun related terms so my hat is off to you sir. Your efforts are to BE applauded and I will enjoy following along....seriously! Nothing comes without science and its mathematics and using a "thing" in a controlled test also constitutes experience. I personally would love to see someone reinvent the wheel. That would be a pretty cool thing to see....

Best wishes in your endeavors 😀 😀 

Bo

 


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(@hector-j-medina-g)
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@straitflite

Bo;

It's not a question of who's "right" or "wrong". There can be more or less precise measurements. Sometimes, as in quantum mechanics, the simple FACT of taking a measurement, affects the outcome ("uncertainty principle").

In airguns things happen so fast, that the human senses have NO WAY to really unravel the whole picture, so SOME FORM of EASILY ACHIEVABLE instrumentation is important to the furthering of airguns themselves.

And AAMOF, I am NOT saying that our measurements are absolute and exact. On the contrary (and we can talk about this later, if you want).

What I am ASKING of everyone that is truly interested in airguns is to build the instrument, and test his/her guns. Even if they do not follow the calibration procedure that John came up with, that is amazingly simple to follow, just the fact that ANY "home tinkerer" can now COMPARE in very effective terms two different rifles in a non-subjective manner is a huge step forward

My HOPE is that by "Popular Mechanic-izing" the INSTRUMENT, we can all start talking in concrete terms about things that, so far, have been only subjective concepts, like "smoothness of shot cycle", "efficiency of the compression phase", "efficiency of the barrel", and even "pellet dwell time".

In the same way that the advent of, relatively inexpensive, Chronographs on the late '80's  came to dispel a LOT of "MYTHS" surrounding the reloading, archery, and airgun world, I do hope that someday, we can all be talking in concrete terms about the firing characteristics of our guns, instead of the old "it kills deader than dead" of the old timers when they were talking about their favorite deer cartridge, or "it is a tack driver with a flat trajectory" of the target shooters. My other favourite one was the "this one bucks the wind, like it's not there" .

After the chronos became available, a lot of those expressions simply fell into disuse, and more solid approached could be followed.

Thanks for the kinds words, I do realized we ALL learn here, nobody is born with innate knowledge, nor with infallibility.

We, together, will drive the future with concrete evidences of what is really happening inside.

😉

 

Keep well and shoot straight!

 

 

 

 

 

 

 

HM

 

 

 

 


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straitflite
(@straitflite)
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Gotcha. The excitement in your words and contributions to this sport are nothing short of well, exciting!

I agree, since the dawn of the internet ambiguous and arbitrary words/terms are/have been thrown about like snowflakes in the wind...guilty here LOL

I'm glad you did not interpret my response in a totally negative way. Large rocks that have been sitting for years can be hard to move. Who's to say who can move them?

With that, I'll shut up and listen since I have nothing to contribute -except that my R7 is "smooth as butter" 🙂 

Wish you well,

Bo

 

 


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(@christ)
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for a springer


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Steve in NC
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Posted by: @hector-j-medina-g

Not an April's Fools joke.

This will be a NINE part series.

We use three of the best recoiling spring-piston rifles ever made.

We will publish one part every two weeks.

https://www.ctcustomairguns.com/hectors-airgun-blog/shot-cycle-dynamics-in-3-spring-piston-airguns-preface

Hope you all enjoy!

 

 

HM

Hector, I'm very much looking forward to your treatment of this complex topic, and in particular to learning some of the details of your "INSTRUMENT!"

 

Thanks in advance, Steve


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(@hector-j-medina-g)
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First Chapter has been posted, where we look at Instruments we can use and instruments we can make to understand the dynamics of the spring-piston airgun:

https://www.ctcustomairguns.com/hectors-airgun-blog/shot-cycle-dynamics-in-3-spring-piston-airguns-chap-1

Hope you enjoy!

 

 

HM


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Bigbore
(@bigbore)
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Posted by: @hector-j-medina-g

 

 AND, more importantly IMHO, is that we will provide anyone that's reasonably handy with the tools and knowledge to create a machine to measure the vibrations in THEIR rifles

This will be an experiment in "Crowd-researching" that HOPEFULLy, will de-bunk some "theories" ("truths"?) that have been accepted and prevalent since the old days and that have hampered the real development of the spring-piston airgun.

 

So, stay tuned . . .    😉

 I'm looking forward to this portion of the series. I made an instrument with an Arduino and a GY521 accelerometer that can be rubber-banded to a gun to test vibration in 3 axes. I can get 4 millisecond readings in its current configuration.

 

 Below is one shot cycle for a .22 rimfire. The axes that should show the most movement do so it looks like it is performing as it should. I want to get the data point times lower but I haven't fooled with it for quite a while.

 

[img] [/img]

 

[img] [/img]


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Steve in NC
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Posted by: @bigbore
...I made an instrument with an Arduino and a GY521 accelerometer...

Nice packages, but I think you'll find the 16g fullscale limit of that accelerometer isn't adequate (like by a factor of 10x) to cope with legendary (scope-busting) springer recoil.


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