Indians For Guns

Dear Friends,
I have worked out for a Effective Set UP for Calculating FPS Of Air Rifle,
Please Put Your Valuable Comments,

The Concept:-
Avisek Chakraborty[HarshVardhan]
Dear Friends I am a Mechanical Engineer ,
Have figured Out Really Easy and effective Technique For figuring Out FPS,
Calculations:-

Concept:- Rifle Is Fired to A Metallic Bell Or anything that sounds, Sound Recorded By PC Microphone, Sound Analyzed To Find Times of Hitting and Firing, Distances Measured.

Distance from Target to Barrel –S
Distance from Microfone to barrel –A
Distance from Target To Microphone -B

• T1 is the Recorded time by microfone when Fired
• T2 is the Recorded time by Microphone while Target is Hitted
• Vs is Velocity of sound 343.2 Meters/ Sec Or 1,126 foot/Sec
So Actual Time of Firing Tf=T1-Time needed By Sound For A=T1-(A/Vs).
Actual Time of Hitting Th=T2-Time needed By sound For B=T2-(B/Vs)


So Time Needed For S distance=Ts=Th-Tf= T2-(B/Vs)- T1-(A/Vs)
Final Velocity Will Be=S/(Th-Tf)


We Know Values of S,Th,Tf[T1,T2,A,B,Vs] Put The Values In Excel Sheet Formula For Easy Calculation



Cost will be Only for Microphone That is around 150 Rs. Only.
if you Use your Mobile For Recording Its absolutely Free of Cost
Now Every One Can Use It.
Software Used for Record and Analysis:-Audacity 2.0.2[Free Open source]
Things You Need:-
1.Measuring Tape,
2.Metalic Object Target
3,Microphone/Mobile Phone with Recording Facility
4.Audacity Software[Free]
5,Excel File Made By Me--Download from-----http://www.scribd.com/doc/115403795
Steps:-
Refer the Set-UP Image

1.Place Target Preferably metallic That Makes Sound
2.Place The Rifle At Distance from Target,
3,Place Your Mobile IN Recording Mode
4.Measure Distances-Rifle-Target,Target-Mobile/Microphone,Microphone Rifle

5.Turn The Mobile IN Voice Recorder Mode
6.Shoot 5-6 Shots for Fixed Metallic Object
7.Transfer The sound File to PC[5-6 shots recorded in one single file]
8.Measure the Time gaps of fire and Hit for each shot[Very easy] in Audacity
9.Put the value in My designed Excel sheet[Formulas Incorporated]
10.Result will be displayed



Pros:-
1.Easy,Free Of Cost,Relatively Accurate

Cons:-
1.Quite Ambiance will be Helpful


Find The Attached File
1.Calculations
2.PDF file Explaining Calculation and Set Up.
3.Sound Analysis By Software-


You Only have to enter Two Times Recorded By Mobile,Others will be Calculated Automatically



Thanking You ALL

Thanks Harshvardhan:
An interesting approach.

Ashok

I have made the excel file for calculation But Unable to post as attachment does not support it

This one is using Phototransistors with IR LED with much accurate, portable & may be cheaper (IR LED & Phototransistor pair cost around Rs.20/- only)

http://www.network54.com/Forum/79537/th ... hronograph

pratik_mahale wrote:This one is using Phototransistors with IR LED with much accurate, portable & may be cheaper (IR LED & Phototransistor pair cost around Rs.20/- only)

http://www.network54.com/Forum/79537/th ... hronograph

Hi pratik,

Thanks for sharing this , I was looking for something like this. it is same approach but instead of collecting sound from mike with lots of noise and echo , you will get two perfect clicks.

Uv

Noise And Echo will not be as loud as firing and hitting target--In the graph you can easily analyze it.Two loud sound will be shown in the graph,
And Its Free of Cost and No Do It Yourself Stuff too.As the Distance is More ,so Chances of Error is also Low.Sound Velocity is also Incorporated for Making it
Error Less
See the graph with Noise and Hit,Hit is easily distinguishable-


Thanks

Keep your mobile or Microphone in the center for more accurate reading

Great idea, thanks for posting!

Thanks ,I am Trying to Re engineering Ball Mouse For Accurate Fps Calculation,
Hope I Can Gift This to All IFG Members as New Year Gift..

harshvardhan wrote:Thanks ,I am Trying to Re engineering Ball Mouse For Accurate Fps Calculation,
Hope I Can Gift This to All IFG Members as New Year Gift..

Thanks and advance happy New year..
See this Link Brother,this type also using Audacity software .
( )
Regards,
RamMani,
Karur(TN).

RamMani wrote:

harshvardhan wrote:Thanks ,I am Trying to Re engineering Ball Mouse For Accurate Fps Calculation,
Hope I Can Gift This to All IFG Members as New Year Gift..

Thanks and advance happy New year..
See this Link Brother,this type also using Audacity software .
( )
Regards,
RamMani,
Karur(TN).

hi Rammani,

principle will always remain same, the quest is how to apply it practically with minimum error. which is shown by harsh and shared post of pratik and that's what actually we should look for.

Uv

In My calculation,Error Is Minimized by incorporating effect of velocity of sound,
I will try to make it more effective by incorporating RamMani's Suggestion
Thanks Every one for your valuable comments

interesting Harshvardhan.....one clarification ;

is your ihp giving you 605 fps at the muzzle or 605 fps at 30 ft ???

or does the the velocity of sound , being a constant negate the distance of the second source of sound ??

what about the velocity of the projectile ?? that is not a constant and would drop with distance, even at 30 ft .

or have i missed out some thing.....

mercury wrote: interesting Harshvardhan.....one clarification ; is your ihp giving you 605 fps at the muzzle or 605 fps at 30 ft ???

or does the the velocity of sound , being a constant negate the distance of the second source of sound ??
what about the velocity of the projectile ?? that is not a constant and would drop with distance, even at 30 ft .
or have i missed out some thing.....

Hi Mercury,
1. FPS is always 'Muzzle Velocity'
2. No - Sound velocity being constant has no relevance to the 2nd source of sound - in fact it works as a reference point.
3. Yes - the velocity of the projectile will progressively drop over distance - depends on:
a) Muzzle velocity
b) Weight of the pellet & its configuration
c) Ambient weather condition such as wind / mist etc.
Briha

Thank You,
You are not only right,you are Accurate,

-The Sound Velocity is Taken into consideration for eliminating error,so it can not negate.
-This is velocity of Projectile only[Pellet]
-Velocity of the projectile will Definitely drop with the distance,Following formula[Negative Acceleration plays it role along with gravity ]
I have Calculated it,But It makes It Complex and Even with negligible effect.So I have Eliminated this from Calculation
I am Making an effective FPS calculator with Calculator[Low Cost Effective Version]
Everything will reflect there.

I appreciate your approach towards calculation,Thanks Again

Regards,