Terminal velocity and how to figure it up

[DanWho]

I was just wondering if anyone can tell me the formula to figure the terminal velocity using the bc and weight of the pellet? Maybe a formula that could gives velocity vs distance traveled with known starting velocity, bc and weight? Knowing both these formulas would give some insight as to Max distance the pellet will likely travel down range. there may even be an app that will have these formulas already available in some form of another.

Thank you
Dan

 

[dreuf]

Chairgun or strelok apps do that very well.

 

[Willie14228]

Dan the Chairgun app shows a graph of when or how far until the shot will fall off after the set zero

 

[DanWho]

Fantastic, will look them both up. Thank you both for the info.

 

[Scotchmo]

This is what I use:

terminal-velocity = muzzle-velocity / EXP(distance / (8000 x BC))

Pellet weight does not matter. You can calculate the terminal (down range) velocity from the muzzle-velocity, BC, and distance.

Edit: for the above formula, distance is in yards.

 

[DanWho]

I wasn't thinking clearly, bc would have the weight and air resistance built into the value, only excuse is trying to get ahead of my self while thinking about momentum and the differences with kenetic energy and trying to fit them together to come up with an answer that really isn't closely related to either but still has a close cousin relationship with both. Have to remember to think in new circles sometimes. My only other excuse could be that I have spent the last 3 months working with tax season that finally ended and am still used to thinking in government math and that kind of math many times doesn't make sense to anyone but the government.

 

[Guest]

That is a pretty good approximation so

terminal velocity (fps) = MV (fps) / EXP(range (yards) / (8000 * BC)) 
OR
terminal velocity (ms) = MV (ms) / EXP(range (m) / (8000 * BC))

Nice.

 

[Scotchmo]

"oldspook"That is a pretty good approximation so

terminal velocity (fps) = MV (fps) / EXP(range (yards) / (8000 * BC)) 
OR
terminal velocity (ms) = MV (ms) / EXP(range (m) / (8000 * BC))

Nice.

Not quite. You need to account for the difference (ratio) between a meter and a yard.

8000 x 0.9144m/yd = 7315

Try this:

when using distance in meters:
terminal_velocity = MV / EXP(range (m) / (7315 * BC))

when using distance in yards:
terminal_velocity = MV / EXP(range (yards) / (8000 * BC))

when using distance in feet:
terminal_velocity = MV / EXP(range (ft) / (24000 * BC))

Edit: the following thread covers BC and applies directly to the topic question
http://www.airgunnation.com/topic/backyard-bc-for-22-cal/#post-79451

 

[Guest]

Got it. Rookie mistake.

 

[DanWho]

How could I figure the time of flight, height, and the terminal velocity if I was dumb enough to shoot straight up in the air? I'm sure I wouldn't need to dive into the nearest bomb shelter, but is a normal baseball cap plenty of protection or would I have to make a quick trip to the army surplus store for a steel pot be in order? I know the math for an approximate height: 32 feet/second squared or 10 meters/second squared will give a general height, air resistance will lower the height some. After reaching the Apex it will accelerate again until it reaches terminal velocity and floats gently to the ground. Is there any way knowing the bc I can figure that velocity?

Dan

 

[AGunBug]

TBH an exact straight up shot, and if there was no wind, no expectation of drag, and not counting for the very minimal amount the Earth will rotate in the moment it reaches apogee and starts its tumble back down, and was to still hit you, well...depending on how thick your hair is, you might not even notice.

Many still believe a penny dropped from the Empire State building, let alone the Sears Tower in Chicago [yes, I know they changed the name, but I am originally from Chicago and any Chicagoan still calls it Sears Tower, much akin to Macy's is still Marshall Fields], that it would kill you, cut right through a car, or embed into the sidewalk. This is not true. Yes, a penny hitting you from that would sting like hell, but that's about it; you'd rub your head and be like, "WTF?!?!?!"

Here are a few helpful links:

Overall how to calculate TV (use link below for handy calculator, but check this link out first so everything can be explained):
http://www.wikihow.com/Calculate-Terminal-Velocity

Terminal Velocity Calculator
http://www.calctool.org/CALC/eng/aerospace/terminal

I hope this helps

--AGunBugMay all of your rifles stay powered and your pellets fly true! 

 

[Mousefart]

ChairGun. Or maybe ChairGun. A 3rd option is to give ChairGun a try. 

 

[AGunBug]

ChairGun is great if you are sitting at your computer, but its mobile application is horrible, rarely updated databases and quite limited when it comes to scopes.

Strelok is absolutely awesome and I would recommend spending the few bucks on the Pro version. When in the field, it is my Go-To application if I ever second guess a shot, and as of so far, it has been dead on balls every single time and I have been using it since January 2017. It has a massive scope database and many more features than ChairGun in terms of ease-of-use, ease-of-access and reliable portability.

There's not a thing ChairGun can do Strelok cannot, and I find that Strelok has more to offer in than ChairGun with a quick reference accessibility.

I know many here love ChairGun, and yes I still use it, but unless I truly have a generic mildot scope or wish to spend the dough on a Hawke scope when my UTG AccuShot is damn good, as well its compatibility for the average air gunner--even an elite one--is as limited as a Buy One, Get One Free at a rock store.

Examples:

This is the best ChairGun can give me since I do not have a Hawke Scope:

Strelok

Now this is what my scope looks like, and although the Strelok has all the added settings on (far distances, MRAD, etc.), but you can switch off my a touch on your screen. If my target was closer or farther away will dictate the hold under's as well via app view, and I love the feature I can email myself or anyone my views immediately from the phone. See the circle upper left with the small rotated 'L' brackets? That's instant zoom!

Here is an example when I recently zeroed my scope @ 12yds to do ratting once I am back home with a max distance we will be shooting is @ 24yds:

Right there, without fail with zero wind is where I need to aim (albeit you can see this without zooming; all depends on distance).

Also, based on location, Strelock will automatically adjust for temperature, pressure and humidity which yes, has more to do with long range shooting say a center-fire, but temperature does have a factor regardless when it comes to shooting anything.

Now, both have the ability to enter your own "Custom" pellet not listed in their DB's, as well as other identical options, but I like Strelok's ability to save your selections without being prompted over and over for every change if you are exiting the program / application.

Just my thoughts on the matter, so choose which one works for you is what it all boils down to.

Just check out the reviews on either the Android PlayStore or The AppleStore in regards to the ChairGun mobile app and it might convince you. If not, download both and try them out, however I am quite certain which one you'll uninstall .

--AGunBug