Non-Spherical Projectiles In Airsoft

[derf]

double post sorry

[greg]

Oh so its better to let the guy throwing the molotov cocktail to catch someone on fire than be hurt himself?

How very Zen.

 

Probably best to post that question in the 'philosophy for beginners' forum.

 

'Cos, as already pointed out, it's getting way off topic.

 

You could always carry on, via pm's.

 

 

Greg.

[Skarclaw]

There's an 8 shot magazine available for a paintball marker which was based off conventional paintballs. All you need to swap out is the bolt and you fire your 8 rounds perfectly fine. The rounds are stacked in the magazine too, so in theory you could have a magazine with 100 of these new paintball rounds and the result will be the same. Obviously it will be a 10 meter magazine, but the point im making is that I think it's pretty straight forward in terms of replicating this for airsoft if theres already a solution for paintball. A single stack staggered magazine similar to airsoft lowcaps is something I envisage for the magazine. For the airsoft gun, well that's a matter of design. Why should it not work for airsoft if it works for paintball already?

 

The main issue doesn't seem to be the magazine or how it loads or whatever, but rather how it would be fairly superlous. You can see why its a good thing in paintball cause they don't have hop systems, so the spin will stablize it better then a normal paintball getting shot out of a smooth barrel, however in airsoft the hop system works, and making a 6mm pellet with fins or whatever probably wouldn't work as well has hop up, and would be more expensive. In short, there is no advantage what so ever.

[Triggerhappychappy]

AIRSOFT ISNT PAINTBALL.

 

A couple low cap magazines arent much use when you could be firing off a few hundred in a days skirmishing, and I mean snipers at that- can you imagine carrying enough per-loaded mags? Or trying to reload them in time between sessions? Or affording them even?

 

Why are you so intent on trying to turn airsoft into paintball? Different weapon platforms, with decades of development to make them reliable (well, excluding the dodgey brands)- its already been tried and no-one was interested.

[Samm]

making a 6mm pellet with fins or whatever probably wouldn't work as well has hop up, and would be more expensive. In short, there is no advantage what so ever.

 

Bingo!

[08kecarv]

Many have tried on this and other forums to 'reinvent the wheel.' The best idea that someone came up with (I forget who) was the dimpling process like a golf ball. Its a tested and very effective projectile BUT again the costs of development and manufacturing outweigh its benefits.

[FELDJAGER]

Regarding the problem of loading a finned round, i think that shell ejectors would be very effective at holding the round in the correct orientation. I agree with Tome though that difference fps and weights will require totally different rounds with different properties; and that spherical bbs and hop ups are "good enough" for now.

[derf]

@ skarclaw & samm: "making a 6mm pellet with fins or whatever probably wouldn't work as well has hop up" - why not?

 

@ trigger: You're assuming there are 3 problems (not enough ammo per mag, reload time, price). Consider that each round is more effective, so you'll need less to score eliminations. Consider that there could be loaders for magazines or that the system itself could be pretty straightforward. Consider that the price is subject to demand and demand is subject to who knows what.

 

I'm only asking if such a thing has been thought of before. Suddenly everyone becomes all defensive and masters of engineering with absurd assumptions. Let's not be dense. If it works in one system, it's more sensible to assume it will work in a similar system that to bash it and say it wont. Especially if you don't supply a reason with the negativity.

[L473ncy]

TL;DR

 

Anyways there was some development in making a "sniper" BB for sniper rifles as a drop in kit however I haven't heard much about it after they made the initial run and did their tests. It was basically a pellet shaped BB and would hold relatively more stable in the air than spherical shaped BB's using hop up. I think the weight they were aiming for was ~.34 grams.

 

The guy was based out of Turkey and IIRC a bag of 500 of these pellets would go for around $25 USD or something.

[Shriven]

Derf: Some of the guys did point out that the size difference may have an effect. Paintballs are much larger and clearly benefit from this skirt, but BBs are so small, that I can't forsee it being THAT useful. They weigh so little that any spin will lob them off course, I mean, the hop up applies the bernoulli principle in order to counteract gravity. If you cant the gun, of fit the hop up nub in not quite the right location, you lose range hugely, because the BB is being spun sideways ACROSS gravity.

There's not enough energy in a BB for it to fight gravity without hop up.

 

They've tried to rifle airsoft guns before, via the Tanio Koba Rifle Twist barrel: It basically created a vortex of air around the BB to increase accuracy, and it was a nice idea, but it only works at relatively low FPSs, and didn't offer that much of an increase over a regular tighbore barrel to be worth buying it over say, a decent 6.03mm barrel.

[England Wonder]

I could see it working with a high energy gun, but I think even sniper rifles firing 500fps with a 0.2g BB lack the power.

a 12ftlb air rifle fires at something like 650fps with a 5g pellet. The spin and stability caused by the wasp shape is far far more effective with them then any airsoft gun.

I like the point about the size of pellet, 4.5mm BBs with the same weight would have a much bigger range due to less drag. They would also fall faster due to the reduced drag and wouldn't make so much uplift from a hop up.

 

smaller BBs might be useful in low power pistols but might also cause problems getting through protection

[TDS]

I could see it working with a high energy gun, but I think even sniper rifles firing 500fps with a 0.2g BB lack the power.

 

Problem is that without hopup most airsofters are unable to understand what a dropping projectile means and wouldn't be able to hit the broad side of a barn, would complain about range, they wouldn't sell and would be a bust financially for whoever made them and the rifles to use them.

 

This was attempted in the past more than once, it just boils down to airsofters being unwilling to compensate for bullet drop and wanting to aim directly at targets at any range.

[kojak]

Many have tried on this and other forums to 'reinvent the wheel.' The best idea that someone came up with (I forget who) was the dimpling process like a golf ball. Its a tested and very effective projectile BUT again the costs of development and manufacturing outweigh its benefits.

 

http://arniesairsoft.co.uk/news2/3868

[A Tobias]

I personally think it would be a novelty in both airsoft and paintball. Who is willing to pay 75p a shot, especially when we can put a couple thousand rounds a day.

 

Obviously this wouldn't be feasible for a hi cap magazine, but for snipers (if this is superior to hop up) the price wouldn't be that prohibitive. Also there are NO snipers who shoot a couple thousand rounds per day.

[Stealthbomber]

The main issue doesn't seem to be the magazine or how it loads or whatever, but rather how it would be fairly superlous. You can see why its a good thing in paintball cause they don't have hop systems, so the spin will stablize it better then a normal paintball getting shot out of a smooth barrel, however in airsoft the hop system works, and making a 6mm pellet with fins or whatever probably wouldn't work as well has hop up, and would be more expensive. In short, there is no advantage what so ever.

What he said.

 

@ skarclaw & samm: "making a 6mm pellet with fins or whatever probably wouldn't work as well has hop up" - why not?

Because firing anything out of an airsoft gun that isn't a sphere means getting rid of the hop-up which reduces range dramatically.

 

The hop-up on an airsoft gun controls the spin of the BB which improves accuracy and also generates lift which improves range.

 

Replacing it with a system that ONLY affects accuracy, does nothing for range and also creates a bunch of problems with feeding and chambering ammo cannot really be seen as a positive step.

 

If it was me I'd be spending my time trying to figure out a way to build a hop-up into a paintball gun rather than spending a fortune on fancy ammo.

I suppose it's possible that a conventional hop-up might cause damage to paintballs but an LRB-style system would probably work.

[WhutJP]

So, I want to see if I have this strait;

With a spherical bb and no hop-up, it's (relatively) inaccurate and has ###### range.

A non spherical bb is more accurate (assuming the shape is right) and has a little more range than a spherical bb.

With a spherical bb you can have hop-up, and this greatly increases range.

With a non spherical bb you can not have hop up and so you can not have the hop-up range benifit.

 

Okay, so the question I want to ask is, would not the addition of tail fins (like the example posted above) also increase range? (if not why not)

If it is a case of 6mm bbs being too small for the fins to affect it much, what about 8mm bbs?

And if it did increase range, would it be more than hop up or about the same?

 

Now I don't have a very deep understanding of physics, particularly the physics of objects flying through the air. The reason I asked the question I did was that I was thinking about those nerf balls with the tails on them, you can throw those a lot further than the usual nerf balls.

 

It would be nice if this could be explained without trolling and arrogance. And as previously said, I don't have a great understanding of physics, so brightly coloured, easy to follow diagrams would be appreciated.

 

[Stealthbomber]

So, I want to see if I have this strait;

With a spherical bb and no hop-up, it's (relatively) inaccurate and has ###### range.

A non spherical bb is more accurate (assuming the shape is right) and has a little more range than a spherical bb.

With a spherical bb you can have hop-up, and this greatly increases range.

With a non spherical bb you can not have hop up and so you can not have the hop-up range benifit.

 

Okay, so the question I want to ask is, would not the addition of tail fins (like the example posted above) also increase range? (if not why not)

If it is a case of 6mm bbs being too small for the fins to affect it much, what about 8mm bbs?

And if it did increase range, would it be more than hop up or about the same?

 

Now I don't have a very deep understanding of physics, particularly the physics of objects flying through the air. The reason I asked the question I did was that I was thinking about those nerf balls with the tails on them, you can throw those a lot further than the usual nerf balls.

 

Blame gravity.

 

Stuff falls at a specific rate regardless of what shape or weight it is.

The only exception to this is when an objects surface-area is large enough that it creates resistance and stops the object reaching terminal velocity.

 

You get a longer range out of a nerf rocket simply cos the additional surface area of the fins adds, proportionally, a lot of surface area while the object weighs the same.

It's the same reason a paper plane flies further than a screwed-up ball of paper of the same weight (when thrown with the same force).

 

When a bullet spins along its axis it does nothing for lift. What it does is remove any random element to the trajectory.

If, for example, you have a bullet that's heavier on one side and you fire it out of a smooth-bore rifle the bullet will probably veer off in the direction where the bullet is heaviest.

In a rifled weapon the heavy part doesn't get chance to cause the bullet to veer one way because, as it spins, it'll exert the opposite effect. The dodgy bullet might wobble slightly as it flies but it should fly straight.

 

To be fair, the hop-up on an airsoft gun isn't as useful as the rifling in a firearm for stabilising a projectile cos the BB doesn't spin laterally.

What it DOES do is control the motion of the BB in a predicable, repeatable way which means the shooter gets far less surprises from BBs doing unexpected things during flight.

 

The lift generated by a hop-up is really pretty clever.

As you probably know, a wing generates lift by creating denser air flow underneath and less dense air flow over the top which means the wing can rise.

A hop-up actually causes the BB to do the same.

Because the BB is spinning backwards friction means it's easier for air to flow over the top half of the BB than it is to flow over the bottom half.

This means the air is denser underneath the BB and lift is generated.

 

A finned BB would not add any lift unless it could, somehow, substantially increase the surface area of the BB in an aerodynamic way while, at the same time, not increasing the weight.

[X Lupin]

There's an old adage I like to live by...

 

"If Asahi couldn't do it, don't even try."

[DrKalinka]

Im going to nitpick on your statement stealthbomber, but it will not add anything significantly to this discussion though

 

Everything has a terminal velocity. If you drop it, the terminal velocity is all the factors like drag, angle, gravity, air density (or water density) and so on.

 

But as Ive said... I'm nitpicking and that is all I came up with, so I think your post really ends this discussion. It would be cool yeah, but it wont work as well.

[greg]

@ greg: what?

What? What?

 

I'll tell you what:

 

My post #10 has explained, that hop will allow a bb to travel further with a relatively flat trajectory, than a skirted, rotating bb.

 

You stated that I was 'wrong'.

 

I'd like you to explain exactly what parts of my post were 'wrong' & go into details as to how you know this.

 

I believe you will find I am right. Saying I'm wrong won't convince me otherwise. Explaining the issue may help me to understand why you think I am wrong. During the ensuing, informative discussion, one of us, may become educated.

 

 

Greg.

[greg]

I'm only asking if such a thing has been thought of before.

Yes it has & every time, my post # 10 was the result.

 

 

Greg.

[Stealthbomber]

Im going to nitpick on your statement stealthbomber, but it will not add anything significantly to this discussion though

 

Everything has a terminal velocity. If you drop it, the terminal velocity is all the factors like drag, angle, gravity, air density (or water density) and so on.

 

But as Ive said... I'm nitpicking and that is all I came up with, so I think your post really ends this discussion. It would be cool yeah, but it wont work as well.

Thanks for that.

 

I know I was kinda simplifying the issue.

acceleration due to gravity IS the same regardless of whether the item is a lump of uranium or a lump of sponge.

The differences occur when one has a different surface area to the other.

Jump out of a plane with a parachute and you'll drop like a stone until you open it.

Once you do that it creates enough drag to slow you down so you don't make a nasty stain when you land.

 

I guess the "skirt" on a BB might increase the surface area a little and, thus, increase the range slightly in the same way that the fins on a nerf rocket do but the proportional difference is what's important to us.

A hop-up unit increases the range of a BB by a helluva lot so it'd have to be a pretty whizzy skirt on a BB to match the performance of a hop-up, never mind improve on it.

 

Thinking about it, I'd like to see more information about these skirted paintballs.

Specifically, I wonder if the main advantage of the skirt is to provide higher FPS by creating a better seal when the paintball is fired?

 

Once again, though, I really appreciate the compliment.

[greg]

The only thing that hasn't been mentioned to this point is drag coefficient.

 

If the finned bb has a lower drag coefficient (is more streamlined), it may go a little further than an unhopped, round bb.

 

Maybe a few%. No where near the extra distance, the backspin provided by a hop gives.

 

At 300fps, with a .2 you will be lucky to see 20m, before the bb starts to dip. This can be doubled with a good hop. A skirted or finned, nonhopped bb woulds possibly do 21m before dipping. A good mathematician will give you an exact figure. If both the round & streamlined projectiles are fired at 45 degrees, the ultimate distance traveled by the streamlined projectile will be slightly further, again, just a few %.

 

Most well fettled airsoft guns will achieve 6" groups under those circumstances at 20m. Possibly 3" groups if you put the effort in.

 

Even if a skirted/finned bb halved this, it will start to drop.

 

As a user, you are faced with a choice; improved accuracy with a true ballistic drop, or standard accuracy with an extended flat trajectory.

 

& then there are the feed issues........................................

 

 

Greg.

[Chimpy]

I hope ballistics talk is okay considering this whole topic is about ballistics!

 

The fins on a NERF Rocket force the center of pressure behind the center of gravity which stabilises it by essentially stopping it flipping end over end. Bullets have the center of pressure ahead of the center of gravity and the longitudinal spin stabilises the round due to the torque resistance of the gyroscopic effect it generates. Range is increased for both as a function of pointing the smallest cross-sectional area forward.

 

BBs on the other hand are spun by the hop to generate lift via the Bernoulli Effect. Range is increased as a function of generating an additional upwards force, counteracting gravity on the projectile.

 

Now spin stabilised projectiles also experience a drift to one side called gyroscopic drift. Also any mass imbalance does make the projectile less accurate and contrary to popular opinion the spin stabilisation doesn't stop that it just makes the dispersion 'even'.

 

The internal ballistics of most paintball markers are also terrible as the barrel and paint clogged in it tend to impart a random spin on the paintball itself which send it off in god knows which direction as it leaves the barrel (due to the same forces that give a hop its effect). I'd imagine the skirt alone on the paintball greatly help prevent this by stabilising the paintball in the barrel. It most likely also increases the energy imparted to the paintball in the barrel. Both these effects combined would end up giving slightly more range and improved accuracy. In terms of it's external ballistics I doubt there is any appreciable reduction in drag and there won't be until the shape of the paintball is more similar to that of a real bullet however the flight is going to be much less random.

 

For Airsoft we're frankly better off sticking with the hop.

 

Edit: Just saw that this is a solid end on the paintball in that less-lethal version, that would make the projectile more aerodynamic and probably reduces drag on the projectile in flight.

[derf]

This discussion is VERY interesting because it seems you are all saying that for airsoft, hop-up provides greater range than a skirted projectile, wheras in paintball, it's the other way round. I'm going to re-read the posts to try and spot the exact reason / factor of why this happens because I seemed to have missed it. I'm also going to dig up some graphs and tests on range regarding paintball hop vs skirted-ammo vs regular ammo.