All about air temp- speed of sound

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FatAlbert
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All about air temp- speed of sound

Post by FatAlbert » Sun Jan 27, 2019 5:37 pm

This something that you need to factor in if loading and shooting SUBS. https://www.weather.gov/epz/wxcalc_speedofsound its all about the air temp.

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Sharkbite
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Re: All about air temp- speed of sound

Post by Sharkbite » Sun Jan 27, 2019 6:14 pm

FatAlbert wrote:This something that you need to factor in if loading and shooting SUBS. https://www.weather.gov/epz/wxcalc_speedofsound its all about the air temp.
Doesnt your altitude play a factor as well?

FatAlbert
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Re: All about air temp- speed of sound

Post by FatAlbert » Sun Jan 27, 2019 6:31 pm

Silent But Deadly: distance above sea level comes into play when you are finding the drop of a fired bullet, because of gravity.

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dellet
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Re: All about air temp- speed of sound

Post by dellet » Sun Jan 27, 2019 6:53 pm

Sharkbite wrote:
FatAlbert wrote:This something that you need to factor in if loading and shooting SUBS. https://www.weather.gov/epz/wxcalc_speedofsound its all about the air temp.
Doesnt your altitude play a factor as well?
Of all factors, temp will have the most effect. What happens with altitude gain is that temp normally drops, so it’s misleading.

Bottom line is that 1050 fps is good basic number to use, good to “0”. There are other reasons to go slower, but if you’re just trying to get rid of the crack, it works.

This is a pretty good explanation with formulas and explanations.

http://www.sengpielaudio.com/calculator-speedsound.htm
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John A.
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Re: All about air temp- speed of sound

Post by John A. » Sun Jan 27, 2019 9:03 pm

temp will have an effect on sound, and I have noticed in winter, there is also less humidity when the temperature is lower.
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Mike7.62
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Re: All about air temp- speed of sound

Post by Mike7.62 » Sun Jan 27, 2019 9:24 pm

Air temperature affects the density of air. Colder means thicker air, hotter means thinner air. Thick air, higher velocity for mach 1, thinner air, lower velocity for mach 1. Humidity also affects SOS, making air thicker or thinner, as does altitude. Higher humidity, thicker air, lower humidity, thinner air. Adiabatic lapse rate for temp is 2*F/1000 ft, meaning temp decreases 2*F for every thousand feet above sea level (ASL), which will affect air density making it thinner the higher you go, which will affect the SOS as well. There are lots of variables in speed of sound calculations, but the number of 1050 f/s is a good one for keeping everything subsonic in most conditions.

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Re: All about air temp- speed of sound

Post by golfindia » Mon Jan 28, 2019 5:22 am

FatAlbert wrote:Silent But Deadly: distance above sea level comes into play when you are finding the drop of a fired bullet, because of gravity.
Please elaborate on this.....

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