Pellets don't rise!

Discussion in 'General Airgun Chat' started by KeithW, Nov 8, 2019.

  1. KeithW

    KeithW Barn door? Where?

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    A couple of years ago an air rifle magazine editor wrote that pellets fly upwards after leaving the barrel before starting to fall. I wrote to him to point out his error and he defended what he'd said and refused to publish any clarification - I think he was too embarrassed.

    Earlier this year an article appeared in the same magazine, written by a very experienced shooter (who frankly should have known better), making the same statement. I wrote to the now new editor and pointed out the error: I didn't get an acknowledgement. I then wrote to the editor in chief and didn't get a response to that either. So then, just to clarify matters:

    In order for a horizontally launched object to rise, it needs lifting surfaces ("wings"). Pellets don't have wings, they don't rise. As soon as a pellet leaves the end of the barrel gravity causes it to start to drop and the further it gets so the rate of fall increases (being the cumulative effect of gravity). You can also add that as velocity slows so the rate of fall increases.

    I think a lot of shooters have gained the wrong idea simply because they use Chairgun which represents the image visually as the pellet rising and then dropping. I accept this is really the best / easiest way to represent the issue.

    Basically it's because we look through the scope in a straight line. The scope is mounted above the barrel therefore the line of the pellet and optical line through the scope would never intersect if the scope was set in a true horizontal plane. But we need the two to intersect to get our primary zero so we angle our line of sight downwards, by using the adjustable reticle. Thus, bearing in mind the pellet is falling, there will be two points of intersection (primary and secondary): but this is not caused by the pellet flying upwards "into" our line of sight, rising above it. then falling through it again, as Chairgun would seem to indicate.

    I spoke with the writer who had made the claim in his article and he maintained that pellets do fly upwards because barrels are angled upwards. A bit of thought tells us that if barrels are angled upwards, or the bore is somehow angled upwards, then the barrel is not actually horizontal. I checked this claim out and found that some target rifles actually had the scope dovetails angled (by 0.02 of a degree I seem to recall) in order to reduce the amount of adjustment necessary for the shooter to make to the scope. In other words the manufacturer is not angling the barrel they are angling the scope.

    I feel better now!
     
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  2. Halesowen Kid

    Halesowen Kid Member

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    Interesting....
     
  3. Dale

    Dale Active Member

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    Technically that would actually be an accurate representation of what occurs when you fire an 'aimed' shot.

    Consider iron sights to start with - you take a direct line of sight to the target, in order to hit that target you have to compensate for the natural fall of a shot if fired from a horizontal barrel.

    By raising the rear sight, you maintain your direct sight line, but, you have raised the muzzle of the firearm relative to that sight line to allow the projectile to hit the target whilst compensating for its fall.

    So the projectiles flight path is now rising to a certain point then arcs back downwards again, an effect of this being you get a 'rising' initial cross of the sight line and the main intersect of the sight line and trajectory at the target distance.

    Of course unless you are shooting at extreme distances the amount of elevation of the muzzle is so small it is still perceived as being horizontal when viewed, but in reality it is not.

    A scope achieves the same basic effect, but it corrects for distance by in effect making it look down towards the position of the falling shot, however, because once again we use a direct line of sight to our target, the shooter is actually raising the muzzle of the rifle to compensate for where the scope is looking.

    The fundamental error is the assumption that you are launching the projectile in a horizontal direction.

    To see this in a more extreme way just look at how artillery is fired, the elevation of the muzzle is far more pronounced but the basic principle is common to all firearms / air guns.
     
    Last edited: Nov 8, 2019
  4. Ferisk

    Ferisk Member

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    Thank you Dale

    ( so .....twats or not ?????? )
     
  5. Dale

    Dale Active Member

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    I would say not all editors are twats, but some of the readers are. :D
     
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  6. AlexS

    AlexS Active Member

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    If I throw a ball up in the air, it flies upwards after leaving the hand before starting to fall.

    I have tested it several times and it is still correct, despite the ball doesn't have wings or other 'lifting surfaces'. The same thing happens to pellets out of barrels. I defend what I wrote and refuse to publish any clarification - There is nothing to be embarrassed about.
     
    Last edited: Nov 8, 2019
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  7. pbrown

    pbrown Bunghole

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    Unless you're shooting with the barrel vertical, there's always a gravitational affect on the projectile in relation to the barrel it has been shot from.

    The pictures below sourced from Brian Samsons article at The low-down on shooting up - CompAir for me explain it well.

    upload_2019-11-8_12-51-40.png upload_2019-11-8_12-52-3.png upload_2019-11-8_12-52-29.png upload_2019-11-8_12-52-51.png
     
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  8. Jesim1

    Jesim1 Active Member

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    The writer is technically correct about the pellet rising when shooting what appears to be horizontally, but omits to acknowledge the gun has to be aiming slightly upwards to achieve this effect :rolleyes:

    I see both sides of the argument, and the OP is also technically correct in what he says, but I also think sometimes we get lost in translation, and to acknowledge every technicality can dilute the subject to a point an article can become unreadable, or certainly confusing, if every i is dotter and every t crossed to give 100% correct technical information.

    As an example - the earth is round (according to some of us:D), so how can anything ever be horizontal - perhaps the flat earthers have a point :eek:
     
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  9. Dale

    Dale Active Member

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    Things can be horizontal over certain distances because the Earth is very big so you need to go quite a distance before the curvature starts to interfere. :D

    This springs to mind for some reason:



    :D:D:D
     
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  10. RobF

    RobF Administrator Staff Member

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    You could say things fall to earth due to gravity but you could also say gravity is a newtonian invention and things actually just travel in a straight line across space time which is bent by mass/energy.
     
  11. Adam

    Adam Well-Known Member

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    Is the line of sight horizontal, or is the barrel horizontal? It's arbitrary and depends on your rifle's trajectory, the elevation of the target and the distance you're shooting it.

    Of course pellets "rise" relative to the ground if you are aiming at a target at the same level as the muzzle. So the line of sight is horizontal but the barrel is angled upwards so the trajectory can intersect with the sight line either when the pellet is rising or falling. The barrel is always angled upwards relative to the sight line, but when level shooting it's always angled upwards relative to the ground as well. So the editor is correct.

    It's more correct, more of the time, to say that the pellet does rise (ie get further from the ground) after leaving the barrel. So I'm with the editor there.
     
  12. Adam

    Adam Well-Known Member

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    This is easiest to show with images of olympic archery. The archers use sights so it's easy to see the line of sight, and they shoot at 70m or 90m at a target whose centre is pretty much level with the archer. In this image the sight pin is in the little nub that's sticking out in front of the sight bar (the T shaped thing with Shibuya written on it)

    [​IMG]
     
  13. RobF

    RobF Administrator Staff Member

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    How many shooters does it take to change a light bulb?
     
  14. Yorkshiretea

    Yorkshiretea B Grade Bandit

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    10, 1 to change the bulb and 9 to moan it wasn't done correctly from the sofa.
     
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  15. dave croucher

    dave croucher FT, the sport where simple becomes complicated

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    Someone make it stop!!!
     
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  16. biwain

    biwain Tree bark and paint chipper Champion

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    Take yer gun to the Moon and shoot it, then yer'd see yer pellet rise yer numpty!

    Wot der yer think yer PBR izz? Stands for Pellet Bloody Rise.
     
    Last edited: Nov 8, 2019
  17. RobF

    RobF Administrator Staff Member

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    Unless it was fired at escape velocity, it would still fall ;)
     
  18. biwain

    biwain Tree bark and paint chipper Champion

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    On'y cos the Moon's got a tiddy bit 'o' gravity!
     
  19. Yorkshiretea

    Yorkshiretea B Grade Bandit

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    Ahhhhh the good old days when Einstien snapped Newtons wand of gravity and things still travelled at 9.8 m/s/s
     
  20. biwain

    biwain Tree bark and paint chipper Champion

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    Gravity, reminds me of Frobury last week. Not a fan of gravity!

    Was rising there!!!!
     
    Last edited: Nov 8, 2019

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