Bb Design....

[Guest]

In the context of the recent thread by @alxndrhll 

 

 https://airsoft-forums.uk/topic/48850-biggest-rif-technology-advancement/?tab=comments#comment-391659

 

 
Please discuss :-

 

“A smooth golf ball hit by a professional golfer would travel only about half as far as a golf ball with dimples”

and

 

”Dimples also affect lift. A smooth ball with backspin creates lift by warping the airflow such that the ball acts like an airplane's wing. The spinning action makes the air pressure on the bottom of the ball higher than the air pressure on the top; this imbalance creates an upward force on the ball. Ball spin contributes about one half of a golf ball's lift. The other half is provided by the dimples, which allow for optimization of the lift force. ”

 

In the context of bb’s.

 

rdb

 

[alxndrhll]

Iiiiiiiinteresting.

 

My only presumption as to why we’ve (or at least I’ve) never seen such thing would be the difficulty of manufacture. I’m going to assume dimples would like add far more difficulty into ensure consistency, as is the nature of creating an irregular surface. But I am aware shapes are weird and engineering certainly isn’t my wheelhouse.

 

I’d also be curious as to whether there is much science behind the size of the dimples, and such science just doesn’t transfer to such a scale. Definitely intrigued to see what folks that are engineers (assuming that’s the field this falls into) have to say on this!

 

Cheers,

Alex

[EDcase]

I imagine the same principles would apply to a smaller spherical body with magnus effect but as alxndrhll said,  cost of manufacture would be prohibitive.

[Guest]

4 minutes ago, EDcase said:

I imagine the same principles would apply to a smaller spherical body with magnus effect but as alxndrhll said,  cost of manufacture would be prohibitive.

Would it be prohibitive though?
 

All bb’s are injection moulded then polished, it would cost more to make a dimpled mould, but not much. Easily possible to design a mould that produces a bb to the correct spec once polished. And dimples aren’t raised.

 

Players already pay a premium for heavier bb’s to increase range, imagine doubling the range, what would people pay?

[alxndrhll]

Not even sure the mould would cost more, granted my experience from moulds for different materials comes from tabletop miniature production. Generally moulds/tooling are a pretty flat rate.

 

As I assume most know, so apologies if it comes across as condescending, the most expensive parts of manufacture are those that require bodies to do the work over machines... I wouldn’t have thought adding dimples would cause an increase in manual work. As such, I wouldn’t necessarily expect an inflation in price for anything other than that which is chargeable due to ‘perceived value’.

 

Cheers,

Alex

[EDcase]

The moulds would be more expensive to produce and not last as long.

Plus I think releasing the BB tree from the mould would probably be harder.

 

May depend on the best design for the dimples...

[Adolf Hamster]

Afaik isnt the range increase from a golf ball more to do with the "drag crisis" transitioning between laminar and turbulent flow around the ball. Roughening the surface just about brings the velocity needed to acheive this down to the velocity it's normally travelling at.

 

I do wonder if there's something going on with airsoft with regards to velocity, somewhere around 280-320fps or therebouts. Haven't done the math on it admittedly.

 

edit:

found a nice picture of it, in this case reynold's number (the x axis) is a function of the fluid velocity, or in our case how fast the bb is moving.

the thing is, for our case we can also adjust the velocity of our bb (note this is raw velocity not necessarily the energy it has) so smooth or rough is probably going to be less relevant as we can adjust our bb's into this range by other means. in the case of a golf ball the velocity is more based on the average golfer's ability to hit the ball which presumably for the better players is probably pretty constant, so roughing the ball works in that scenario.

 

the question i have, and imma have to sit down and get freaky with excel again to prove it is would this benefit outweigh the gains given by running heavier ammo at lower velocities? intuitively i'm going to say no as from my personal experience even as low as 1j a .48g bb still flies much further and straighter than a .3g 

[Skara]

This isn't new.

I remember someone actually testing dimpled bbs.

 

https://www.airsoftsniperforum.com/35-sidearms-optics-gear-accessories/58025-silo-s-new-bbs.html

 

https://www.airsoftsniperforum.com/32-general-sniper-talk/55463-golf-ball-technology.html

[Lozart]

5 hours ago, Adolf Hamster said:

Afaik isnt the range increase from a golf ball more to do with the "drag crisis" transitioning between laminar and turbulent flow around the ball. Roughening the surface just about brings the velocity needed to acheive this down to the velocity it's normally travelling at.

 

Basically, yes. https://www.scientificamerican.com/article/how-do-dimples-in-golf-ba/

 

In theory it's possible to achieve this with a BB, whether or not it's practical to do so is another matter!

[Cr0-Magnon]

The real question is, do we really need our BB's to travel further or should we spend more time working on our cardio?

[Lozart]

2 minutes ago, Cr0-Magnon said:

... or should we spend more time working on our cardio?

 

HA HA HA HA HA HA HA HAH AHA HAAHHHA AHAHAAH HAHAAAHAAHHHAAAAAAAAAAA!!!!!!!!!

 

 

 

 

 

No.

[Adolf Hamster]

11 minutes ago, Cr0-Magnon said:

The real question is, do we really need our BB's to travel further or should we spend more time working on our cardio?

 

you work on your cardio all you like, you'll only die tired

[Cr0-Magnon]

I'm not claiming to be Mo Farrah out there but we as a community do chase range and accuracy too much. Even on large woodland sites we're "engaging" at about 40 metres

[Albiscuit]

Three great points here so far:

1) My initial thought was great idea, then worried about the manufacturing. Would it be possible? how would you QC a batch with dimples? if the dimples were out of off slightly wouldnt you then have bbs pinging off in any direction? Also would the science work for such a small projectile? I guess in theory it should but would it?

 

2) Yes, from my experience 80% of airsofters (myself included) should be doing more cardio   

 

3) How much would you pay for "better" BB's, well I think BBs are generally cheap. I use ASG Blasters, I tend to buy them by the box load and think even without the box discount about a tenner for 3000 shots is bloody good value so I would happily pay double to significantly increase range and effective accuracy range. However unless these magical balls of plastic could be made cheap enough to be in 90% of peoples budget I dont think they should be made.

Imagine doubling your range with bbs which cost a lot, we are talking £20 per hundred.  it would create such an unfair advantage for those who could afford them (but lets face it, if they were that dear I doubt there would be a market for them)

 

 

[Adolf Hamster]

14 minutes ago, Albiscuit said:

3) it would create such an unfair advantage for those who could afford them (but lets face it, if they were that dear I doubt there would be a market for them)

 

airsoft is already full of unfair advantages, for example as CR0 points out being physically fitter is a massive advantage, and not everyone can solve that problem by just going to the gym (although granted a lot of us can and probably should)

 

it also needs to be pointed out that no matter how good your hardware is, it isn't going to stop you getting outplayed, sure you might be able to outrange the guy in front of you but that's not going to stop the sneaky bugger in the bushes behind you.

[Albiscuit]

Good point actually, theres always a player or two with better range, accuracy or just "better" at the game than you. 

 

It was more about limiting the ability to buy an advantage, but then that happens in every hobby, sport and aspect of life, TM over a cheaper brand, HPA over a springer for ROF for example.

[alxndrhll]

Interesting but not surprising that it’s come up before. Having thought some more on it I’m also going to assume that this sort of BB would need adjustments in the hop up design to get any sort of consistency. This could be that my brain is struggling to picture what exactly a 6mm golf ball would look like, but given the money we shell out for ‘super precision’, ‘super polished/smooth’ BBs I’d certainly need some convincing before I dare run them through a regular system. Irrelevant of the quality I can’t help but think that sort of design would be prone to getting snagged on hop buckings... but this could just be me failing to visualise what these things would actually look like!

 

1 hour ago, Adolf Hamster said:

 

airsoft is already full of unfair advantages, for example as CR0 points out being physically fitter is a massive advantage, and not everyone can solve that problem by just going to the gym (although granted a lot of us can and probably should)

Weirdly lands on a somewhat similar point that came up in the thread which saw the birth of this one.

 

I think more players than you’d think—myself included in the past—that things like site limits exist to try and create ‘fairness’ alongside the safety reasons. I suspect that’s just naivety on my part, given that outside of ‘field specific’ restrictions there aren’t really any sort of fair play guidelines to followed when it comes to what your RIFs can do. This isn’t to say I’d want them, just an observation that this side of ‘fair play’ just doesn’t seem to be much of a consideration in a hobby which involved charging around with luxury toys. Sorry, I fear I’ve gone off topic at the end here... but not enough to delete it all? 🤷🏻‍♂️
 

Cheers,

Alex

[PopRocket123]

Wasn't this an April fools joke a couple of years ago?

[EDcase]

There's already a purchase advantage for those who can spend more on a 'better gun'.

 

BB's are only one part of the system so even if they existed and were better, they would only produce the best results when the rest of the gearbox and hop are working properly as they need to now...

I would guess snipers to be the main users of better BB's

 

What about the advantages of having a hi-cap vs mid-cap or HPA.  I think those make more of a difference in a game.

[Adolf Hamster]

57 minutes ago, Albiscuit said:

Good point actually, theres always a player or two with better range, accuracy or just "better" at the game than you. 

 

It was more about limiting the ability to buy an advantage, but then that happens in every hobby, sport and aspect of life, TM over a cheaper brand, HPA over a springer for ROF for example.

 

tbh with airsoft it's very much a case of diminishing returns when it comes to performance, it's relatively easy to get 80-90% performance out of *most* systems, and that little difference is something that can easily be overcome with playstyle.

 

i remember once having a hell of a duel with a chap in a grassy section of a site, he was running jeans, t-shirt and a battered rental spec g36, whereas i definately had the on-paper advantage of my labour of love hpa'd m4 which has been a very long and expensive journey into chasing every last minute of angle possible. despite having a theoretical kit advantage i got absolutely destroyed, repeatedly, because he was a sneaky bugger who knew the site like the back of his hand and could literally run rings round you.

 

and that's just one example of hundreds, i'm not going to say that better kit isn't nicer to use and can open up opportunities (for example my primary tactic relies on shooting people who don't think i have the range to hit them), but it doesn't guarantee success in the same way that being one with the bushes isn't going to help much if you can't hit the broad side of a barn from 10 feet.

 

7 minutes ago, EDcase said:

BB's are only one part of the system so even if they existed and were better, they would only produce the best results when the rest of the gearbox and hop are working properly as they need to now...

I would guess snipers to be the main users of better BB's

 

this is the main point i think when it comes to performance, no one factor can overcome another being sub-par, doesn't matter how good the ammo/hop/barrel is if the compression is lousy etc etc.

 

snipers tend to use the better bb's because they don't shoot enough of them for it to be too expensive, i'm mad enough to occasionally run .48's in an assault gun and you can hear the "cher-ching" of money leaving the barrel with every trigger pull, needless to say i don't do it often because good lord is it expensive.

 

[Adolf Hamster]

ok so bit of an update to this

 

due to the boredom of lockdown figured i'd have a crack at seeing if the drag crisis has any significant effect on our bb's and as far as i can tell the answer seems to be no.

 

in the chart above the drag crisis starts around Re<10^5.

 

for a sphere moving in air Re is given as Re=pvd/u (there's meant to be greek symbols of rho and mu but i cba typing them out properly)

where p=the density of air (~1.225kg/m³), v is the velocity of the fluid (or very loosely approximated the velocity of the bb in m/s), d is the characteristic length (again loosely approximated to 6mm) and u is the viscousity of air (~18.5*10^-6 Pas)

 

so if you run the numbers for an 0.2g bb at 2.5j you get Re=62818 which is well below the transition point.

 

in fact you need to be over 6j before you get to the region where the the drag crisis starts to become an effect of note.

 

of course this is very approximate, and as with all calculation based approaches it's entirely possible i done goofed.