I have been playing around with some old ballistic programs and was just curious if anyone here knew the coefficient of drag for the typical 6mm bb. I imagine almost all will be similar, especially once washed so their rate of deceleration from resistance should be pretty consistent.

Thanks.


Ps, a quick sub topic. Has anyone toyed with the idea of a bullet shaped 6mm round? Of coarse it would have to be for a specially designed gun from almost the ground up to even have a chance of working. This could open doors to better aero through slightly pointed projectile and even boat tail rear ends, barrel rifling would be possible. Then there is hop up. Everyone wave bye to hop up. Aside from much higher energy setups the range would be drastically limited due to the loss of hop up. Perhaps a bullet shaped bb with an impact/crush section that causes the bb to crush itself in the middle when it contacts to reduce some of the impact on the target by absorbing a small amount of the kinetic energy. Seems much to complicated to actually work but fun to think about.

I would still love to see dimpled bbs like a golfball, hopefully with a softish bucking you could still get consistent spin. Imagine the distance!

I would love to dance to the theory we could be talking about and such, but maybe a different day friend :)

You should find the data you seek online.

There are a lot of fields that may not approve of a bullet shaped bb projectile for airsoft purposes.

Enough problems with Insurance/Field and the players exist with players using high fps builds with heavy bbs and such, this would be over the top.

I am not saying its a bad idea, but for skirmishing, yes I believe it is a bad idea IMHO.

As I have mentioned in other threads, Bioval had some Dimpled bbs created but again, it was FAR too expensive for users to play with them so they never reached mass production.

For now I suggest working on the various Hop up mods that make use of the current bbs we have or perfecting the heavier bb's as almost every brand above 0.36g has had air pockets [waiting on that guy who always posts after I say something like this xD], I.E. the OEM brands: Guarder/Madbull/King Arms/Matrix/Javelin etc....and even Bioval 0.40g have air pockets and BB Bastrd.

Goldenball does not from all my tests of cutting them up but they are black... :( no good unless you are dead on sighted with say a visible version of the same weight and even then you need to account of other factors but I will leave it at that.

Sorry, I am not trying to harsh on your ideas at all. There is merit to them but these are just my opinions on the matter.

Good job though :)

Yeah convincing insurance companies that the fps/energy doesnt matter as much with a new designed projectile would be a long hard battle. As I said though without the higher fps the loss of hopup would be too much to recover from alone. I suppose you could get into real ballistics if the projectile was stable enough. though with no backspin and such low fps(relative) these things drop very fast and it is very unlikely anyone is going to hold up 7 feet above a target at 200 feet(I made the numbers up yes) even if it is consistent. and the thought of spinning .25 minute clicks is for different ranges with that kind of drop is just funny, not to mention most scopes would never adjust that far, so Kentucky wind age it would be, and that is hardly consistent.

Anyway I found the CD for the bb, since it is, hopefully, a perfect sphere the CD should be .47 (while my car is .28 ;p). I will plug some numbers into my ballistic comp tomorrow when I get off work, no time now. But it will be interesting to see if even theoretically its worth it to change to a boat-tail design or a teardrop even (CD of around .04!!!).


Can you think of any way to precisely make a form or press that would somehow dimple airsoft bbs on the user end? I can think of easy ways to do it with a drill or a press with a form, but both would not be precise enough imo to actually benefit(more likely hinder) accuracy.

I found some achiac posts about the bioval Dimplex bbs, sounded fun but im out of time now to read up more.

Hi there.

Yes, c_d might be about that value. I don't happen to know off the top of my head what the Reynolds number of a typical BB in flight, since the drag coefficient is going to vary depending on the flow, which is dependent on the velocity. Then, to toss another little wrench in there, when you have a spinning sphere, that messes with the drag coefficient as well. I don't know how intricate your ballistics program is, but if you're looking to determine the flight characteristics of a normal hopped up BB, make sure your program is accounting for the lift that the backspin is producing, and not just the flight pattern of a ballistic object with a given c_d. If it doesn't have that ability, you're going to just have to estimate the rotational velocity of the BB, and if you're going to do that, why not just take a look at the ATP?

Coincidentally, there's a thread over on ASM that came up recently about alternative projectiles for airsoft. I tend to agree with HS5's analysis of the situation, though it would be interesting for that to be proven wrong.

First Strike Rounds were made to fill the demand for "sniping" in paintball. They can supposedly be used effectively up to like 400 feet, but the testing was non scientific. Can't find that video now.

http://en.wikipedia.org/wiki/Drag_coefficient

If you want to get really specific on that number, you are going to have to find the Reynolds Number which I believe is based on the velocity of the bb relative to the air around it.

This post has been edited by airborne101: Jul 30 2011, 05:46 PM