Calculating bullets deceleration

[Ray B]

If I understand the ballistics programs correctly I should be able to enter the variables: bullets ballistic coefficient and initial velocity, barometric pressure, temperature and initial elevation. Then if fired straight up in addition to the decrease due to air resistance I would subtract 32 feet per second per second velocity for each second of the bullets flight until its velocity is zero. Is this thinking correct? and for the calculation which program is preferred?

 

[fourfive8]

Yes, that sounds like the correct way to calculate it. However I don't think the calculators include the changing air density for a bullet flying straight up. The calculator probably only uses an average air density based on temperature and altitude in a more or less horizontal plane (actually a parabolic curve though the air in that horizontal plane) where the differences of air density due to changes in altitude of the bullet would be minimal. Just have to see if a calculator like JBM can be "massged" to handle vertical flight predictions. Post the results- interesting question!

 

[Shootist43]

Ray B, just curious, why are you asking the question?

 

[fourfive8]

Why? ... we’re all going covidcrazy

 

[Shootist43]

Why? ... we’re all going covidcrazy

That is precisely what I was thinking.

 

[K E Johnson]

When doing this calculation, don’t forget to allow for the coriolis effect...........

 

[Ray B]

The reason was that a few years ago there was a dictator (seems to me it was Sadam Husane) who was trying to get into the ballistic missile business with artillery that could send shells into the atmosphere. So I was wondering just how much BC and velocity it would take to accomplish it. Using a ballistic program, a BC of .8, initial velocity of 3000 fps, fired from 35,000 feet and using a charted barometric pressure which has increments at 5,000 ft intervals based on 30.0 at sea level the answer that I get indicates the bullet would top out at well short of 100,000 feet, which is still well short of getting a bullet to an elevation where it would break free from the Earths atmosphere and be used as a ballistic weapon, so I'm wondering just what sort of cannon the dictator had in mind- the Germans had one they could fire into France but that was a parabola similar to Earth gravity ballistics. So just wondering.