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Re: Effects of air Temperature on Subsonic load speed
Posted: Thu Dec 26, 2019 8:31 pm
by dellet
Thank you for posting that, that will give you a real look at actual applications of why altitude does not matter for subsonic shooting.
An elevation change of 5000 feet, will have less influence on the speed of sound than most peoples extreme spread of a 10 shot string. It's statistically irrelevant
Re: Effects of air Temperature on Subsonic load speed
Posted: Thu Dec 26, 2019 9:04 pm
by rebel
If disagreeing -
Have you played with your posted calculator?
Re: Effects of air Temperature on Subsonic load speed
Posted: Fri Dec 27, 2019 2:39 pm
by Suputin221
Blowout wrote: ↑Wed Dec 25, 2019 6:32 pm
Altitude change will change the velocity of the round. With increased elevation there is lower air density which will allow for an increase the velocity of the bullet everything else being equal. Altitude can’t be ignored as a contributing variable to a subsonic load. Similar effect as increasing temperature...
You are confusing velocity with drag. If you shot a bullet in a vacuum, it wouldn't go any faster than one shot in air. However it wouldn't slow down because there would be no drag, unlike a bullet shot in air.
Thus, at altitude, bullets do not start out faster than ones shot at sea level. What they do is go further because there is less air drag.
Re: Effects of air Temperature on Subsonic load speed
Posted: Sat Dec 28, 2019 1:57 pm
by popper
Yes I verified it works, as pointed out above, for us, no practical difference. Unless you are shooting Yeti on Everest (or 50bmg @ 1 mi. or more). NASA site has been dumbed down from ~15yrs ago, mostly for kids now. Trying to push kids toward science now but schools don't teach good math or science anymore. Just push computer buttons.
edit" tidbit - f86 had a problem when first introduced with 30 cal, running into own bullets at top speed. Me109 had a problem with spent 20mm cases, can't toss them in the slipstream as they hit the plane. IIRC the thunderbolt with 4 blade prop and big engine had same problem in straffing power dive. About the time they started using BT ammo to keep BC up. Airspeed and muzzle fps don't add exactly.
Re: Effects of air Temperature on Subsonic load speed
Posted: Sun Dec 29, 2019 4:24 pm
by rebel
popper wrote: ↑Sat Dec 28, 2019 1:57 pm
Yes I verified it works, as pointed out above, for us, no practical difference. Unless you are shooting Yeti on Everest (or 50bmg @ 1 mi. or more). NASA site has been dumbed down from ~15yrs ago, mostly for kids now. Trying to push kids toward science now but schools don't teach good math or science anymore. Just push computer buttons.
edit" tidbit - f86 had a problem when first introduced with 30 cal, running into own bullets at top speed. Me109 had a problem with spent 20mm cases, can't toss them in the slipstream as they hit the plane. IIRC the thunderbolt with 4 blade prop and big engine had same problem in straffing power dive. About the time they started using BT ammo to keep BC up. Airspeed and muzzle fps don't add exactly.
That's why I edited my last post, wasn't sure if your were using that to prove air density had an effect, which the calculator clearly shows "not much, if any". If you really want to go down the rabbit hole, we can get into how sunlight effects POI. Trust me, way more than how dense the air is. Those discussions tend to keep you awake at night and experiment at the range while mumbling to yourself.