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YingKid

BB flight distance

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I just came across this table in an old post on the forum. Is this correct? If so, can someone explain to me with a bit of science how a heavier bb can fly further that a lighter one??? I consider myself pretty knowledgeable in science but this has me completely baffled.

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At any given FPS a heavy BB has more energy and will fly further. You have to keep in mind that switching from 0.20g BBs to 0.30g BB's will reduce the FPS as well.

 

A 1.14J 0.20g BB will fly leave at 350 fps and fly 169 feet.

 

But a 1.14J 0.30g BB will fly leave at 265 fps and fly bewtween 130-145 feet.

 

So actually a heavier BB will fly less far given the same energy input, because its travelling slower which is only somewhat compensated for by its increased density that counters air resistance better.

 

But if the BB has more energy and starts at the same speed then the increased density will allow it to counter air resistance better and travel further, or rather it started at higher energy and hence has to loose more before its speed substantially drops. Air resistance is effectively the same force in both cases, but the input force given the same speed for a heavier BB is much higher.

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I consider myself pretty knowledgeable in science but this has me completely baffled.

 

 

That's because you're most likely applying basic physics, in that an object will fall at the same speed and reach the ground in the same time, regardless of it's horizontal velocity.

You're forgetting that airsoft guns (with hop ups) but backspin on the BB, which keeps it in the air for longer. What BrightCandle said above about comparing distance of heavier BBs with lighter ones at the same FPS is right; the heavier ones will have more energy behind them.

Even at the same energy, a heavier BB may travel further (to a certain extent) as it will be less effected by drag and will slow down less.

 

If I were you, I would only rely on the table as a very rough guide though! The actual range you get out of your gun will be dependent on many factors and will be very specific to your gun. Even if someone had the exact same gun as you, with the exact same parts, giving the same power output and using the same BBs, you'll most likely get different ranges due to very small differences.

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Basically it comes down to kinetic energy. i.e. how much energy the thing has stored in it as it moves. Heavier objects store more energy as they move.

 

Push a big heavy car at ten mph and then try to stop it by grabbing it with your hands, then do the same with a baby's pram. You can stop the pram easily in comparison to the car. Now substitute that analogy for BBs of differing weights, where your hands are replaced by aerodynamic drag, form drag, parasitic drag etc, i.e. all the things the air is doing to slow something down; the air has a harder time stopping the heavier BB because, like the car versus the baby's pram, the heavier BB has more stored energy.

 

One of the trade offs is of course that a heavier BB will have more ballistic drop because if the heavy and the light BBs are both given the same rotation by a hop up unit, their similar size and shape means they will both be creating the same amount of lift. If that lift is sufficient to keep the lighter BB flying level, it won't be sufficient to overcome the weight of the heavier BB.

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At any given FPS a heavy BB has more energy and will fly further. You have to keep in mind that switching from 0.20g BBs to 0.30g BB's will reduce the FPS as well.

 

A 1.14J 0.20g BB will fly leave at 350 fps and fly 169 feet.

 

But a 1.14J 0.30g BB will fly leave at 265 fps and fly bewtween 130-145 feet.

 

So actually a heavier BB will fly less far given the same energy input, because its travelling slower which is only somewhat compensated for by its increased density that counters air resistance better.

No. The first column is the fps measured with 0.20g BBs. Heavier BBs will fly farther form the same weapon. They start at lower speed but they loose their speed slower. They even reach the target faster from about 30-40 meters and up.

 

As for the original question: these values seem to be valid according to my experience.

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Heavier BBs go further, mass and velocity are only 2 factors from a pool of MANY factors which affect an airsoft gun's range.

 

There's a really well thought out and modelled explanation of the whole system here;

http://mackila.com/airsoft/atp/

 

Thanks for everyone's answers. Interesting answers but man, I didn't expect to see a thesis on this subject! Bookmarking it on my phone so that I can read it on the toilet... :)

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I've just skimmed this thread, but i straight away noticed a few people saying that heavier BB's have more energy than lighter ones - in simple terms this is not true in use (although there is debate about a phenomenon known as 'joule creep' however it's effects, if any, are quite small). Momentum is a function of mass x velocity so when a 0.2g BB leaves the muzzle at 328FPS it has 1 Joule of energy - the same gun shoots a 0.25g BB @293.4FPS = also 1 Joule

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Interesting subject, I have wondered about it too.

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I've just skimmed this thread, but i straight away noticed a few people saying that heavier BB's have more energy than lighter ones - in simple terms this is not true in use (although there is debate about a phenomenon known as 'joule creep' however it's effects, if any, are quite small). Momentum is a function of mass x velocity so when a 0.2g BB leaves the muzzle at 328FPS it has 1 Joule of energy - the same gun shoots a 0.25g BB @293.4FPS = also 1 Joule

 

 

Yeah, not sure if you're picking that out of what I said, but if so, I mean at the same FPS as a lighter BB, not necessarily from the same gun.

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