Author Topic: 100 Yard challenge/Cyclone  (Read 15795 times)

Offline PelletPaul

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Re: 100 Yard challenge/Cyclone
« Reply #15 on: February 22, 2009, 09:33:01 PM »
Thanks Stan.  Try again in a few weeks.           Paul
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Offline SAVAGESAM

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RE: Follow-up
« Reply #16 on: February 23, 2009, 12:53:26 AM »
Quote
MEHavey - 2/22/2009  6:36 PM

Sorry guys,... but wind has nothing to do w/ pellet drop, and the rest is pure ballistics.
An 830fps (muzzle) pellet reaches the target w/ ~430fps remaining,for an average velocity of ~615ps over the 100 yards

That means a half second flight time to target w/ a resulting 4-ft drop by pure 1/2aT(sq) math.Tilting the barrel up to compensate for a scope 1-1/2 inches above the boreline when sighting at 25yrds reduces the net drop to ~28 inches, not four. Ain't no way around the simple physics

Paul is correct.
IMHO, I think you need to be more specific. There are variables that come into play here. A super light weight pellet may leave the muzzle @ 830 fps  but might not be close to 430 fps  after 100 yards. Where as, a heavier projectile (say a 21.1 Gr. .22 Cal. Beeman Kodiak) leaving the muzzle @ 830 fps might arrive at 100 yards with more than 430 fps.  What do you think?
Beeman RX-1 .177 Cal./  http://www.talontunes.com    T.T./A.F. Condor .22 Cal. Thanks Tony.

Offline MEHavey

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RE: Follow-up
« Reply #17 on: February 23, 2009, 01:20:20 AM »
Good point.  Here's the data...

The case above was the old standard/Crossman Premier 14.3gr/0.0190BC being kicked out at 21.8ftlbs (which is what the/my RWS460 family produces by direct comparison with the 350 in question)

The 21-22 ft lbs is the constant.  Heavy or light, you get roughly the same energy out of the RWS springer.

The heavier 21.1gr Kodiak at pushed out with that 21.8ftlbs starts at 683fps (0.0360BC) and reaches the target at 485fps -- faster than the lighter CP.  But it started slower so average speed is lower and it actualll takes slightly *longer* to reach the target.  As a result, the Kodiak zeroed at 25 hits 33" low at 100.

My personal favorite, the JSB Exact Heavy at 18.0gr/0.0310BC, goes out at at 739fps for that 21.8ftlbs, and reaches the target with 508fps remaining for roughly the same average flight time as the Crosman Premier -- and has the same drop of ~28 inches at 100 yards.

Offline MEHavey

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RE: Follow-up (to the follow-up)
« Reply #18 on: February 23, 2009, 01:25:33 AM »
The  really light 12.5gr Super Bear (12.5gr) does go out approaching 900fps for 21.8ftlbs.  But its lousy BC means that its down to 285fps (!) at 100 yards -- making it slowest of them all over the course -- with almost a 40" drop.

Offline melloroadman

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Re: 100 Yard challenge/Cyclone
« Reply #19 on: February 23, 2009, 03:58:38 PM »

Offline MEHavey

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Re: 100 Yard challenge/Cyclone
« Reply #20 on: February 23, 2009, 04:12:50 PM »
A pellet always starts at a speed relative to the stationary muzzle.  But reference the air around it, it quickly adopts different groundspeeds.

A 15 mph headwind will subtract 22fps from the effective muzzle velocity (reference the ground speed)
A 15 mph tailwind will *add* 22fps reference the groundspeed

These are maximum figures, and practical effect is somewhat less that this in both cases, but no matter.  We'll analyze using max effect.

The standard 20ft-lb Crosman Premier start outs at 830fps, and when zeroed at 25 yards strikes 28" low at 100 (no wind).
With the 15mph headwind, it will find itself adopting an apparent 808fps initial groundspeed, and impact 30" low at 100.
The 15mph tailwind will cause an apparent increase in groundspeed to 852fps at the muzzle, and hit 26" low at 100.



Offline MEHavey

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Re: 100 Yard challenge/Cyclone
« Reply #22 on: February 23, 2009, 04:26:32 PM »
Pellets are usually shot with crosswind, which DOES affect lateral dispersion.  But the headwind/tailwind component has little relative effect.  (See above)

Offline MEHavey

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Re: 100 Yard challenge/Cyclone
« Reply #23 on: February 23, 2009, 04:27:29 PM »
Pellets are usually shot with crosswind, which DOES affect lateral dispersion. But the headwind/tailwind component has little relative effect on drop. (See above)

Offline MEHavey

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Re: 100 Yard challenge/Cyclone
« Reply #24 on: February 23, 2009, 04:28:15 PM »
Pellets are usually shot with crosswind, which DOES affect lateral dispersion. But the headwind/tailwind component has little relative effect on drop. (See above)

Offline MEHavey

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Re: 100 Yard challenge/Cyclone
« Reply #25 on: February 23, 2009, 04:30:30 PM »
Pellets are usually shot with crosswind, which DOES affect lateral dispersion. But the headwind/tailwind component has little relative effect on drop. (See above)

(Don't know why this is posting in the wrong sequence)

Offline MEHavey

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Re: 100 Yard challenge/Cyclone
« Reply #26 on: February 23, 2009, 04:31:02 PM »
test

Offline PelletPaul

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Re: 100 Yard challenge/Cyclone
« Reply #27 on: February 23, 2009, 09:40:00 PM »
Marvin - Good looking chart you sent there.  I need to study the format and try and understand what it is saying.  Wonder what the FT shooters do when the wind is blowing hard?  Bigger targets I guess.       Paul
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Offline DanoInTx

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Re: 100 Yard challenge/Cyclone
« Reply #28 on: February 25, 2009, 12:07:19 PM »
Thanks Marvin, I had read about the "S" ballistics due to wind a long while ago, but never could find the link again.  This isn't the same link, but is the same info.  Great stuff!!!
Dan

Current shooters: Beeman HW97K .177 with Hawke Eclipse 4x16x50SFAO and Steve C. stock, Beeman R9 .177 with Hawke Airmax 4-12x40AO and Gene\'s Midas touch, Air Arms S200 with Bushnell Banner 6x24x40AO Rowan brass bling and Steve C. custom stock, BAM B25, BAM B40 .177 with BSA 3x12x44AO, Benjamin Marauder .22, Benjamin 397 pumper.

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Air gunzzzzzz, air gunzzzzzz, air gunzzzzzzz!!!  ...You will feel better\" T.E.C.2008

Offline MEHavey

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Re: 100 Yard challenge/Cyclone
« Reply #29 on: February 25, 2009, 01:21:15 PM »
The resulting 'S' curve, however, is greatly exagerated left and right -- as much as +/- 12 feet left & right at a 1,000 yards for a mere 10mpg wind at right angles for a 200gr 30 caliber bullet starting at 2,800fps.

But as that 15 mph wind swings around to be a headwind or tailwind, however, the rise and fall of the impact point changes only +/- five inches