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Author Topic: Testing a space capsule with noise  (Read 1742 times)

Chris Hindle

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Re: Testing a space capsule with noise
« Reply #10 on: March 13, 2017, 01:41:32 am »

It depends at what distance the measurement is made at.

But it is actually not all that hard.
Well, not for YOU guys at Danley...........  ::)
Chris.
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Jonathan Johnson

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Re: Testing a space capsule with noise
« Reply #11 on: March 13, 2017, 02:43:58 pm »

From my days in military avionics, I remember strapping things to 20" voice coils and various other things to test them.  There was even a place in SoCal that would load a plucked chicken into a howitzer and fire it at a test unit.

But are those organic, free-range chickens?
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Tim McCulloch

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Re: Testing a space capsule with noise
« Reply #12 on: March 13, 2017, 04:39:25 pm »

But are those organic, free-range chickens?

There were upon launch....
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"Practicing an art, no matter how well or badly, is a way to make your soul grow, for heaven's sake. Sing in the shower. Dance to the radio. Tell stories. Write a poem to a friend, even a lousy poem. Do it as well as you possible can. You will get an enormous reward. You will have created something."  - Kurt Vonnegut

brian maddox

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Re: Testing a space capsule with noise
« Reply #13 on: March 14, 2017, 09:54:34 pm »

It depends at what distance the measurement is made at.

But it is actually not all that hard.

I acknowledge that Danley can do this.  I also acknowledge that the numbers I used originated from my rectal region....
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brian maddox
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andy craig

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Re: Testing a space capsule with noise
« Reply #14 on: April 05, 2017, 02:16:54 am »

The article is pretty light on specifics, but interesting.

http://www.popsci.com/why-lockheed-martin-is-blasting-orion-crew-capsule-with-noise-from-1500-speakers

I have a blurry memory of Tom Danley chiming in on a thread on the old LAB talking about his work with NASA back in the day. The thread was originally about what was the most powerful amplifier ever. There was a lot of talk about Crest 10001s and the like and then Tom talked about the amp they built back in the early days of the US space programme.
There had been a lot of launch failures in the early days, so a team was put together to reproduce the SPL at launch and see if that would shed any light on the problem.
The team did manage to build a transducer which achieved the target and they discovered why the launches were failing.
IIRC the spectrum had, as well as a heap of low end, a spiky HF element at 8k(?). When these higher frequencies were introduced to the test signal at the appropriate SPLs, a bunch of machine screws unscrewed themselves. Problem identified.
It was a very interesting read. I've tried a search of the Archives but couldn't find the original thread.
Cheers,
Andy
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Ivan Beaver

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Re: Testing a space capsule with noise
« Reply #15 on: April 05, 2017, 07:31:01 am »

I have a blurry memory of Tom Danley chiming in on a thread on the old LAB talking about his work with NASA back in the day. The thread was originally about what was the most powerful amplifier ever. There was a lot of talk about Crest 10001s and the like and then Tom talked about the amp they built back in the early days of the US space programme.
There had been a lot of launch failures in the early days, so a team was put together to reproduce the SPL at launch and see if that would shed any light on the problem.
The team did manage to build a transducer which achieved the target and they discovered why the launches were failing.
IIRC the spectrum had, as well as a heap of low end, a spiky HF element at 8k(?). When these higher frequencies were introduced to the test signal at the appropriate SPLs, a bunch of machine screws unscrewed themselves. Problem identified.
It was a very interesting read. I've tried a search of the Archives but couldn't find the original thread.
Cheers,
Andy
Resonant frequencies can be quite interesting.

It is not just low freq that cause issues, sometimes it is much higher.

And you have to be "dead monkey nuts on" in order for it to take effect.

Just like a buzz in a speaker cabinet.  Some freq don't do anything-but when you sweep it and stay on the problem, it will "take off" and be really bad,

But a couple of Hz higher or lower and there is not an issue.
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Stephen Kirby

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Re: Testing a space capsule with noise
« Reply #16 on: April 05, 2017, 07:35:37 am »

We used to use a strobe set slightly off the frequency of the vibe table so you saw a "difference" or a really slow beat of the part apparently moving in slow motion.  The amount of displacement in an apparently solid contraption was really disconcerting to watch.
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David Allred

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Re: Testing a space capsule with noise
« Reply #17 on: April 05, 2017, 11:16:04 am »

So once again,like the "brown note" in Mythbusters, the subs are arranged in a circle.
I'm sure it's loud but would a wall of them all stacked together not create an even better low freq source?
Either way, would not want to be in that capsule...if you dare  ;D

As I recall, they were cycling 8hz.  Seems they stated having a hard time breathing.
I had a similar experience during a root canal.  The suction was overpowering my lungs.  Not a pleasant experience.

I think that "brown notes" exists, but only for those "ripe" with a virus or other chronic conditions that require an effort to "Keep it together". :o ???
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