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Spud guns DB-Sound, G-Vibration and Ns-Velocity measurement

A place to ask general spud cannon related questions.
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Spud guns DB-Sound, G-Vibration and Ns-Velocity measurement

Unread postAuthor: D3vil5ro53 » Wed Jul 30, 2014 6:35 am

Hi to all I searched and searched but could not find post about how and where should we measure those things. This came in mind as I thought to measure my spud gun DB in the feature. And it is different when measuring from distance or near the barrel. If this thread has been mentioned before then sorry. However, I thought I would post my ideas on how and where to measure so all of us could compere our results equally.
To measure the DB there is a free app for android here https://play.google.com/store/apps/details?id=kr.sira.sound
To measure the G there is a free app for android here https://play.google.com/store/apps/details?id=kr.sira.vibration

My idea how to measure is that the spud gun is mounted to a stationary wood base.
*To measure the DB and G then the device is located with those specs.
The length of the spud gun divided by two and then this length is added from the center of the spud gun to the location B.
*To measure the Ns then the device is located with those specs.
The length of the spud gun is added from the center of the spud gun to the location A.
Image

Looking for your feedback what you all think?
If anyone has any better ideas let us all know!
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Re: Spud guns DB-Sound, G-Vibration and Ns-Velocity measurem

Unread postAuthor: jrrdw » Wed Jul 30, 2014 9:23 am

Do a keyword search of "chrony" and you should see the archives of Spudfiliers who have done this by sound but with different equipment. It will be a good read for you.

P.S. You no longer need approval to post...Congrats!
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Re: Spud guns DB-Sound, G-Vibration and Ns-Velocity measurem

Unread postAuthor: SpudBlaster15 » Thu Jul 31, 2014 1:06 pm

There's approximately zero chance that the mic in a smartphone is going to be able to accurately process a high amplitude, short period sound wave like a cannon report, and thus zero chance that the number reported by the application will be correct. In my experience, many of them also peak at something absurdly low like 90dB SPL.

You might have more success using the built in accelerometer to measure recoil acceleration, but I somewhat doubt it.

In short, you're going to need real instrumentation to get meaningful results from this testing.
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Re: Spud guns DB-Sound, G-Vibration and Ns-Velocity measurem

Unread postAuthor: D3vil5ro53 » Mon Aug 04, 2014 7:52 am

Looks like its my forum birthday (no more approval for posts)

If i have time over i will test the build in mobile phone mic vs a real db reader.
I will post the resoults here.

And thx for the tip i will search the archives for my question.
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Re: Spud guns DB-Sound, G-Vibration and Ns-Velocity measurem

Unread postAuthor: D_Hall » Mon Aug 04, 2014 10:32 pm

For what it's worth, we've measured over 800 G vibrations at the muzzle of VERA. They were lateral Gs and associated with barrel harmonics. Longitudinal Gs? I don't recall the numbers for sure but there was a heavy vibrational component there as well. I want to say on the order of 150 Gs.

And no, you're not going to measure that with a phone.
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Re: Spud guns DB-Sound, G-Vibration and Ns-Velocity measurem

Unread postAuthor: jackssmirkingrevenge » Wed Aug 06, 2014 9:35 am

A cheap and reliable dB meter would certainly be of interest! Putting a figure on "my launcher is f***ing loud!" would be fantastic :D
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