trajectory question

[wmitty]

Forgive me if I'm out of line for asking this question here, but I'm well aware that there are some very knowlegeable members here who probably know the answer without a second's hesitation. The highest point in a bullet's trajectory is not half the distance between muzzle and target ( mid-point trajectory height) because of drag; the trajectory curve being a parabola. My question is, at what distance from the muzzle ( percentage of total range to target) is the trajectory at it's highest point above the line of sight? I can see it's around 60% from looking at the ballistics tables ( Hornady's 3rd edt. pg. 551: 7mm 162 gr. BTSP 1000 yd. zero shows traj. ht. of 98.9" at 500 yds and 99.7" at 600 yds) but I have never been able to find where the highest point is located. Any input would be greatly appreciated and again, if I am asking this in the wrong place I apologize!

[grumble]

wmitty, I'll let the smart guys expound on this more, but the short, easy answer to your question is, "it depends." There will be no set percentage of total range that will be the hight point on every trajectory because of differing ballistic coefficients (BCs) with different projecticles. Worse, different bullet shapes have different BCs and their velocity decreases and drag drops accordingly. (Drag is proportional to the SQUARE of velocity, so a little chage in V makes a big chage in D).

Hope that muddled things up enough to answer the question. <GGG>

[Junior1942]

wmitty, go to www.huntingnut.com and download the free ballistic program.

You'll need to know some things about your firearm and load to use the program: (1) bullet velocity; (2) bullet weight; (3) bullet ballistic coefficient; (4) distance of sighting above bore, usually about 1 1/2" with a scope and 3/4" without a scope.

If you don't know your bullet's ballistic coefficient (BC), then find a similar bullet with a known BC and use it. You'll get close to your bullet's trajectory.

[sundog]

If you shot straight up (not necessarily all that good a thing to do) then the highest point if the trajectory should be exactly half the range. That sounds like a carpetman explanation, sorta. Don't it? And, if you shot straight down, there wouldn't even be a trajectory. Dang, I hope it's not catching.... sundog

[Tom Myers]

wmitty

Its like Grumble says: "It all depends" I have attached two screen snaps of the trajectory calculations of a 270 and a 40-65 in 200 yard increments out to 1000 yards.

As you can readily see from the "Maximum Ordinate Range" Values that the shorter ranges are only about 51% downrange for the short ranges and 53% downrange for the slower 40-65, while the 270 bullet increases from 51% at close range up to 58% on the 1000 yard range.
*********
Well, the attachments did not work - here are the values:

Range.....Max Ord Range...Percentage... Max Height

270 @ 2700 fps w / BC of 0.456
200yd........102.9yd........... 51.5%..........2.8 in
400yd........212.1yd............53.0%..........3.7 in
600yd........327.9yd............54.7%.........38.0 in
800yd........451.3yd............56.4%.........84.7 in
1000 yd.....579.7yd............58.0%.........167 in

40-65 @ 1216 fps w / BC of 0.400
200yd........102.5yd........... 51.3%........13.8 in
400yd........208.0yd............52.0%.........63 in
600yd........315.1yd............52.5%.........159 in
800yd........423.7yd............52.9%.........310 in
1000 yd.....533.8yd.............53.4%.........530 in

Hope this helps,
Tom Myers
Precision Ballistics & Records
http://www.tmtpages.com