GTA
All Springer/NP/PCP Air Gun Discussion General => Air Gun Gate => Topic started by: Cal on November 19, 2012, 11:16:16 PM
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Interesting topic starter for those who have read it.
BEST shooting pell went out the bore at 1216fps! and it was a light one.
Hmm....
"Vibration vs Velocity" I'm curious!
Cal
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yeass i read that and agreed with him as my diana 460 shoots 177's out at 1050-1075 f.p.s. and is the most accurate gun except for my diana 54 that is just behind it speed wise ,both are extremely accurate and everybody keeps tellin me that a 177 over 1000 f.p.s. wong group. dont tell my guns that fact . neither seem to buzz or viberate like my 34's do they arent bad but they do vibrate a bit . im interested in the viberation control he is testing ,if it works we might have some real tack drivers
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Speed of sound is 1088 or so @ sea level. When something goes trans-sonic, there is a bit of upset, both passing the SOS coming and going.
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Speed of sound is 1088 or so @ sea level. When something goes trans-sonic, there is a bit of upset, both passing the SOS coming and going.
That return trip is no problem if it happens at impact! LOL
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Yeah, I'm with Red. Tom does need to do more testing before hanging a hat on that argument.
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I thought I read that when a pellet breaks the sound barrier (@ 1088fps as stated in an earlier post here) that the pellet tends to tumble and therefore will in most cases not be accurate. I've tried those "light" pellets in my Winchester 1000 .177 and never had any luck with them.
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The speed of sound in dry air at 70*F is 1130 fps.... It varies with temperature, but does not vary directly with altitude.... The reason sound travels slower in the Stratoshpere is that it is colder up there....
Bob
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I saw a review on youtube by edgunUSA on the hw100. Its a pcp rifle so it should have less vibration then a springer. He was shooting the .177 version and couldn't get it to group well. He slowed down the video and you could see the pellet start to tumble as it broke the sound barrier. I suggest you guys check it out. Maybe some of your rifles are shooting well at 1080fps because they haven't broken the sound barrier yet. So they haven't started to tumble. Like rsterne said maybe the sound barrier was higher that day because of the temperature. But on that video of the HW100 you can clearly see the pellet start to tumble and go off coarse.
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It starts at just over 85% of speed of sound.
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Is this "tumble" a design limitation of dibolo pellets?
I have a pair of AR6 renegades that shoot pretty straight and always with the "CRACKKK" of going supersonic. (1225fps chrony)
I know the rimfire guys choose the slower loads for bench rest (<1000fps) but there are a lot of shots fired every day at 1250+
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1225fps is right at supersonic, so there won't be much, if any tumbling. Under 950fps is okay too. The "transonic" region (Mach 0.80-1.20) is where there's stability problems. It affects pellets, bullets, aircraft etc. I've seen some neat photos of jets passing thru it.
http://upload.wikimedia.org/wikipedia/commons/thumb/d/d0/FA-18_Hornet_breaking_sound_barrier_%287_July_1999%29.jpg/640px-FA-18_Hornet_breaking_sound_barrier_%287_July_1999%29.jpg (http://upload.wikimedia.org/wikipedia/commons/thumb/d/d0/FA-18_Hornet_breaking_sound_barrier_%287_July_1999%29.jpg/640px-FA-18_Hornet_breaking_sound_barrier_%287_July_1999%29.jpg)
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I have a 177 shooting 10 grains at 1050 FPS, and its very accurate. Anything below 8 grains though goes SS, and groups horribly. I read the same piece when my mailing came, and found Tom's methods lacking a lot of controls that could answer his questions. The effects of turbulence or what have you as you reach SS speeds are well documented, and given that pellets reach that speed only briefly, then fall away from it quickly imo subjects them to a lot of instability. Throw in the poor design of the diablo pellet and it seems a given that reaching SS would cause serious accuracy issues.
If he really wanted to get a solid result, why not just solidly mount a PCP and film the effects of various speeds on various pellets from the same gun with the same conditions? Once established whether or not going SS really affected pellet trajectory, THEN he could move on to the effects of vibration.
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At least for my winchester 1000......the heavy pellets H&N FTT 10.65 do the best (in the high 700's) Lighter pellets....not so much.
PaperPunch1
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The speed of sound in dry air at 70*F is 1130 fps.... It varies with temperature, but does not vary directly with altitude.... The reason sound travels slower in the Stratoshpere is that it is colder up there....
Bob
i believe the altitude reference is because of barometric pressure. i could be wrong.
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Speed of sound change with pressure is a common misconception.
The velocity of the air molecules (on average) determines the propagation speed of a "sonic vibration" That speed changes with temperature. A gas at a higher temperature has a higher average velocity for each molecule than does "cold gas". Sound moves faster in warmer air. It just so happens that both temperature and pressure usually decrease with altitude. But it's the temperature that matters to sound.
Now a lighter than air balloon is more interested in the pressure.... but that's another matter.
\
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like i said, i could be wrong.
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Yea, Bob's right. It's temperature.
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I think that everyone should keep in mind about the answer given about TG! He's a {SALES MAN} he gets paid to promote products and ideas to help sales of items!!!!!!!!!!!! that said, theirs nothing wrong with .177cal guns with bigger power plant pushing heavy pellets at reasonable speeds as long as their accurate but all of the theories here are in the ball park about speed, Speed isn't everything accuracy is! from my own experience and I've seen this in allot of airgunners they think they need a gun shooting Mach 2 to ac hive their goals and I don't know if its the fact they don't or cant understand how to use mildots or what the deal is but you can do just about anything you need to do with a spring gun at 800 to 850fps in any caliber! JMO :P
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Preachin' to the Choir here Bro. .177heavies @900 works.
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To the gentleman's credit. He did layout and describe exactly what he was doing.
Anyone could draw their own conclusions.
Unless they had never experienced a magnum springer jumping in their hands when fired ;-)
The topic is "Vibration vs velocity".
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that's kinda the point were making a good tuned spring gun with no vibration shooting in the velocity's I posted will far serve you better then a hyper magnum that's not lubed and springy,twangy,buzzy, what ever you want to call it? the point is all that power will destroy your rifle! a rifle that's full of vibration is not lubed or fitted properly and will accelerate ware on the parts and have a bad shot cycle and won't be as accurate as a tuned gun, that's the conclusion people have come to find out by shooting such guns! but what do I know? I kinda understand the point TG is making but I think if I'm gonna take advice or learning something about AG's it ain't gonna be from him! I'll listen to the PRO tuners who have done this stuff for over 40+yrs or more! just my extra 2ct :P
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i think that pellet will do very poor at 50-60 yds.
mark
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i must go with what tom said . my 54 and 460 both are very smooth shooting,no twang or buzzing . both will shoot better than i can see . i let a friend who has a gun store shoot my 54 and he was pleasently suprized at how smooth and accurate it is . my 460 has a tad of recoil but no twang at all . i had a daisy hatsan that twanged bad and you was lucky to hit a barn broadside . also a smooth shootin gun will outlik=ve a viberating gun 10 to 1 . i use either rws superdomes or cphp's sometimes boxed domes but they both shoot in the mid to upper 1050 1000 fps
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if a pellet slows down bellow the speed of sound quickly after leaving the gun the transition from supper to sub will have a lot of time to affect it's path if the target is far off, if the transition happens 2 ft from the target there will be no effect. the guns vibration is not the only thing happening at the muzzle the supper sonic effect is there at the departure too. they are no doubt working together.
mark
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if a pellet slows down bellow the speed of sound quickly after leaving the gun the transition from supper to sub will have a lot of time to affect it's path if the target is far off, if the transition happens 2 ft from the target there will be no effect. the guns vibration is not the only thing happening at the muzzle the supper sonic effect is there at the departure too. they are no doubt working together.
mark
Is the pellet already traveling supersonic as it exits the crown? That would cause the entry effect to be controlled by the barrel. It would only be the fall off to subsonic downrange that would cause issue.
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the shockwave would impact the barrel as the pellet entered the air at supersonic speed and cause some? disturbance?
mark
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????
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guys we are floggin a dead horse . however like tom said he was testing a new piece of equipment that controls viberations . and if it works he will post about it . and if it does there will be a lot of $$$ made by the manufacturer the first few years. might be a place to invest in stock and drop them when it looks like it peaked
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Keep your hand tight on the wheel and your wallet.
He sure isn't going to revise aero dynamics or physics with that tact.
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i think the viberation dampener is part of the gun not a new addition to it. a viberation tunable spring gun is nothing new
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Sales Gimmick! :P
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Someone must like them
http://www.benchrest.com/timeprecision/SUPERTUNER/supertuner.html (http://www.benchrest.com/timeprecision/SUPERTUNER/supertuner.html)
http://www.ozfclass.com/articles/1/psm_2005_03.html (http://www.ozfclass.com/articles/1/psm_2005_03.html)
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I'm gonna look at it like this if you have a quality AG and its some what tuned and you have the best pellets that the rifle likes and you have some shooting ability you should have no problem shooting a ragged hole @30yds smaller than your pinkie nail! and gizmo's like that are not needed! if a guy needs things like that to aid his shooting ability theirs something wrong some where! JMO :P