Ballistics and how less power is more energy delivery.

[EDcase]

Ok, how about this?

Fact - Your Joules is fixed.

Your variables are BB weight or Velocity.

So where are your joules going?

Simple, if you want speed, you put your Joules in to velocity by lowering BB weight.. Tadah!

Its a bit more complicated than that with airsoft BBs. Look up 'Joule Creep' but...

Yes, a heavier BB will go slower and possibly further because its less affected by wind but that's nothing to do with what the video is showing.

 

[AirSniper]

Here, play with this and see how the relationship of BB weight and joules energy affects your FPS.

View attachment 80907

https://www.zerooneairsoft.com/airsoft_fps_calculator

View attachment 80908

 

[Adolf Hamster]

i'm starting to think there are 2 very different conversations going on here........

 

[AirSniper]

i'm starting to think there are 2 very different conversations going on here........

Three actually.

One fixed and two vary depending on your use of that input

If your input is fixed weight BB then your fps will depend on the joules input, I think this is what people are getting hung up on.

If your input is fixed velocity then your Joules output is affected by the BB weight

If your input is fixed Joules then your Velocity is affected by the BB weight

This is why it helps to see things like the diagrams as it shows where your power / energy is going to or what is sapping it.

 

[Adolf Hamster]

Three actually.

One fixed and two vary depending on your use of that input

If your input is fixed weight BB then your fps will depend on the joules input, I think this is what people are getting hung up on.

If your input is fixed velocity then your Joules output is affected by the BB weight

If your input is fixed Joules then your Velocity is affected by the BB weight

This is why it helps to see things like the diagrams as it shows where your power / energy is going to or what is sapping it.

you're literally just describing the three variables in the kinetic energy equation wherein Ek=0.5*Mp*Vp^2

but that's far from the only equation at play if you want to know the answer to how much energy a bb with given starting properties (mass, energy and spin) will have at a certain distance, or indeed as most airsofters really care about how much distance can they get the bb to go.

 

[AirSniper]

One final one, this shows that a 0.2 g BB that is swapped for a 0.4g BB has this effect on the FPS, losing about 86 feet per second in velocity.

View attachment 80909

 

[AirSniper]

Spin improves the BB's flight and yes, there is a cost involved because that spin has to cost energy as it was also imparted after the original energy has been put in to it.
 

You would have to shoot in the same barrel but with a hopperless and a hoped up version of the barrel to see the effect of the spin on energy and its power.

You would chrono those two to get your data and see the effect of the hop up unit in action.

For this exercise, its been simplified to ball park figures. If you want to get technical and use all the variables, I did post a link to a very comprehensive calculator that would calculate if you could hit a target by adapting your rifle aim method like the aim angle, are you hold over or hold under to hit the target? 

If you were high enough up, you would see the effect more readily than a firearms shooter, the direction you shoot in also affects the projectiles distance and trajectory, eg, shooting east, bullets drop earlier than shooting west, all due to the spin of the earth, shooting north or south introduces drift. Add in wind, humidity, elevation and your distance to target and you can work out if the bullet or projectile you use will get there.

There are so many variable that even the thermal build up in the projectile from the resistance (friction) of air that it too can affect the trajectory.

Also, how the projectile left the muzzel, is is true and straight or has it yaw spin or pitch roll or tumbling?

How far do you want to go. I am keeping it simple as that is all that is needed.

 

[Adolf Hamster]

yep, definately 2 different conversations going on here.....

at this point i'm not even sure what the point that's trying to be made is  :wacko:

 

[AirSniper]

No its not, its thsame conversation but the data you get depends on where you start.

Back to the beginning...

The op of another thread was complaining that his 200fps on a 0.8 joule rif with a 0.4g BB was not giving them the speed that they wanted.

The reality was that a 0.4g BB on an 0.8 Joule rif is 207 feet per second, allow for variance, they were already there...

Then the conversation went off on a tangent with ballistics in this thread because it was an attempt to demonstrate the relationship of BB weight to FPS from a fixed energy input, which shows exactly waht I am trying to rteiterate time and time again...

You can not get out more energy than you put in, there are only losses, these can be sound, heat, light, velocity and energy depending on what you do.

As the Joules is fixed, you have to decide where you want your joules to go, do you want velocity so you get the distance in the shortest time, hit your mark and bugger the energy dump 

OR

run with heavier BB's to run slower FPS and longer flight time but hit your mark and dump the energy in the BB in to the target.

Only way you are really going to get down with this is to get a chrono, different weight BB's, start throwing them and chronoing the speeds and record the joules and fps per BB weight.

I did just that with some pistols and I will be repeating the experiment again but in a more controlled environment wherte I can record things like humidity, temperature, gas type, etc and chart it in a spread sheet and then I plan on posting it here as its pretty interesting to see how fps and joules vary from the BB weight.

Early data, my M&P 9 does better on 0.25 and 0.3g BB's than 0.2g or 0.28g, which was surprising. The M92F favours 0.28g than anything else.

So each weapon, cannon or airsoft RIF will have its own characteristics and losses, these are the things that I believe people are chasing because they see the figures on the tin and expect that to be the minimum. Unfortunately, reality is ae a box of surprises and disappointments as shown here.

 

[Rogerborg]

yep, definately 2 different conversations going on here.....

at this point i'm not even sure what the point that's trying to be made is  :wacko:

I'm backing slowwwly away from one of them, I think it's a bit bitey.

 

[EDcase]

Yeah, I think everything got confused by referring to the video as an example of lower velocity = more energy into target which ONLY applies to hollow point spin stabilized projectiles.

Saying that lower energy = lower velocity or heavier projectile = lower velocity is just following the formula so not in contention.

Are we all happy? ?

 

[ImTriggerHappy]

As the Joules is fixed, you have to decide where you want your joules to go, do you want velocity so you get the distance in the shortest time, hit your mark and bugger the energy dump 

OR

run with heavier BB's to run slower FPS and longer flight time but hit your mark and dump the energy in the BB in to the target.
 

Except that the fps evens out after a short distance and starts to swing towards the heavier weight bb as the lighter one bleeds off energy faster once it leaves the barrel.

And now I am running away before I get caught in another argument where people try and adjust facts to fit their point.

 

[AirSniper]

Here is some early data from a quick chrono test.

If you plug in the data in to the Zero one calculator and do the convertion, you see that variances exist and its pretty close to the change you expect with higher withg BB's on a fixed power input that affects the velocity.

Thus showing that you want to speed up your BB's you have to go light weight.

The video demonstrates (for the umpteenth time) that the fixed point is the slug weight and the variables were the pressure input of power in joules and the resulting FPS.

Which as demonstrated, the sweet spot was 3700 ish PSI (from memory) which if you calculate it is 4880.8799 Joules that was put in to generating the higher velocity than the higher psi of 4500psi or lower psi than the sweet spot.

It demonstrates the same thing with  BB only your fixed source is your power rating in Joules.

Do you not recall how you moved equations around in school to work out things from a couple of known elements, only the data you have needed the equation changing to fit your needs, like V = I/R in electrical engineering, you can find Amps ( I ) from the Voltage and the load resistance in watts. It similar process, you move the element until the desired parts are the answer.

I have suggested people play with the Zero One calculator as it shows exactly what I am saying and I don't understand why people don't get this fact, its based in real life physics.

View attachment 80910

Same pistol, same Joules, different BB weights.

 

[Adolf Hamster]

I'm backing slowwwly away from one of them, I think it's a bit bitey.

thought i had it for a while there, but now i'm definitely lost again.

 

[noctu]

thought i had it for a while there, but now i'm definitely lost again.

View attachment 80911

 

[ImTriggerHappy]

I have suggested people play with the Zero One calculator as it shows exactly what I am saying and I don't understand why people don't get this fact

Because you are looking at it too narrowly.

Your results are based on a chrono which is a couple of inches from the end of the barrel. A bb is very light and that low mass is hugely affected by air resistance.

All this has been done and proved ages ago and it was proved that a heavier bb bleeds off energy at a slower rate and after about 30ft if everything is set properly the heavier bb is equal to the lighter bb and after that is usually travelling faster.

Set your chrono about 35ft away and then test but make sure you use a real one not some £40 hobbyist one.

 

[Rogerborg]

Set your chrono about 35ft away and then test but make sure you use a real one not some £40 hobbyist one.

Ackchyually, we had a good bun fight a while back about how we should be using direct measurements of impact energy, which would make the entire fps / BB mass issue moot.

Sadly, I couldn't find any cheap solid state components that claim to be able to measure the sort of small (energy and size) impulses that we'd be getting with anything like the required level of precision. So then you're left with trying to hit a pendulum and measure its swing, and it all goes a bit Rube Goldberg.

 

[ImTriggerHappy]

Ackchyually, we had a good bun fight a while back about how we should be using direct measurements of impact energy, which would make the entire fps / BB mass issue moot.

Sadly, I couldn't find any cheap solid state components that claim to be able to measure the sort of small (energy and size) impulses that we'd be getting with anything like the required level of precision. So then you're left with trying to hit a pendulum and measure its swing, and it all goes a bit Rube Goldberg.

If you know the fps and weight and can get your shots through the chrono it is easy enough to work out.

I built a steel inner for my skan when I made replacements for the malls ones a few years back and tested it myself over 40mtrs in an indoor environment.

 

[Adolf Hamster]

at this point should we maybe rename this thread to the grand unified theory of airsoft?

i think so far the only topic we haven't taken a tangent into is the #knownfact that tm recoils don't abide by normal physics

oh bugger....

 

[Rogerborg]

my skan

Oh, I'm surprised you didn't have your butler do the shooting for you.