Has anyone got access to real BP pressure curves ?

[dtknowles]

"Burn Rate" charts have gotten more people in more trouble than loose women.

"Burn Rate" is the speed of unpressurized powder.
It is only ONE factor in a powder's ballistic response:

- Burn Rate/sec
- Energy content (Heat/Kg)
- Ratio of specific heats (specific heat at constant pressure vs and the specific heat at constant volume)
- Progressive (or de-gressive) burning rate (with increasing pressure)
- Progressive burning limit (at which point it quits increasing pressure)
- ...and last but not least: a "Factor b" to balance the thermodynamics

As you can see, don't ever use simple Burn Rate to estimate loading results.

Are saying that you disagree and that Unique is not the powder that will most closely represent Trail Boss of those Larry suggested?

Tim

[mehavey]

- Delete -

[mehavey]

I am saying that published "Burn Rates" are near-meaningless when all the
factors affecting internal ballistics actually get going upon ignition in a cartridge

[KenH]

Attachment 275589
http://www.texas-mac.com/Black_Powde...bturation.html

That is the best combining of those graphs I've seen. Thanks for posting - I'll really be glad when Larry gets his results posted so we can see some good graphs.

[KenH]

I am saying that published "Burn Rates" are near-meaningless when all the
factors affecting internal ballistics actually get going upon ignition in a cartridge

A very good illustration showing difference in powders. That QL program is really great, as long as a person doesn't forget it's only a theoretical calculation and actual results might vary some, but it does get loading data in the ball park.

[mehavey]

Except for Fill volume, RED DOT acts more like TrailBoss in Max Pressure and Risetime.

In fact the curves overlay to the extent that I'd be almost tempted to say TrailBoss is
merely 'puffed' Red Dot (shot from guns, so to speak)




(But life can't possibly be that simple)

[dtknowles]

Except for Fill volume, RED DOT acts more like TrailBoss in Max Pressure and Risetime.

In fact the curves overlay to the extent that I'd be almost tempted to say TrailBoss is
merely 'puffed' Red Dot (shot from guns, so to speak)




(But life can't possibly be that simple)

Yeah but Larry did not offer to test with Red Dot.

Tim

[mehavey]

All I really want is the BP pressure/time curves. Data that
as far as I can tell either doesn't exist, or isn't available.

Everything else is gravy since I can then extrapolate from the
relative responses of the other powders he is going to test.

Not to worry.....

[dtknowles]

All I really want is the BP pressure/time curves. Data that
as far as I can tell either doesn't exist, or isn't available.

Everything else is gravy since I can then extrapolate from the
relative responses of the other powders he is going to test.

Not to worry.....

Post #40 had three black powder curves

[mehavey]

Without any units (other than apparent Peak Pressure), and without any related-
relative curves (other than "rise" which is/isn't 10-90% ?) with w/o anything but "Trailboss"

Which in earlier curves is shown to be (apparently) much Faster than BP.
(But that can't possibly be -- since BP is supposed to be faster than anything)

Let's wait for Larry....

[dtknowles]

Without any units (other than apparent Peak Pressure), and without any related-
relative curves (other than "rise" which is/isn't 10-90% ?) with w/o anything but "Trailboss"

Which in earlier curves is shown to be (apparently) much Faster than BP.
(But that can't possibly be -- since BP is supposed to be faster than anything)

Let's wait for Larry....

Are you kidding me about BP being faster than anything. Trail Boss is fast but not the fastest powder. Certainly there are smokeless powders that faster than BP but I don't think that Larry is testing with one that is. Unique might be a close match for FG but slower than FFFG. The next fastest powder he suggested 2400 is almost certianly slower than FFFG.

Another thing you mentioned is with smokeless the speed depends on conditions. If you limit smokeless to BP pressures they all get slower. Some will not even burn right at those low pressures.

Why won't your software make plots for BP?

Tim

[dtknowles]

Without any units (other than apparent Peak Pressure), and without any related-
relative curves (other than "rise" which is/isn't 10-90% ?) with w/o anything but "Trailboss"

Which in earlier curves is shown to be (apparently) much Faster than BP.
(But that can't possibly be -- since BP is supposed to be faster than anything)

Let's wait for Larry....

The related curves are shown in the pictures, the plots are probably about 2 ms long since that is the likely barrel time. You can just drop a graph on them like I did in the comparison plot I made. I think they would be more accurate than the plots you posted from QL.

Tim

[Larry Gibson]

Take notice in drawn or, in particular, the computer generated traces they are nice and smooth with even curves going up and down. Many, if not most pressure traces, especially those at the low end of the 45-70 loads being discussed, are not smooth curves. So, if they are not smooth curves, as in illustrations, do not be surprised or assume something is "wrong".

Also, the computer generated curves and drawn curves are based on one input of data. What is will post will be the pressure traces and data of all the shots on each test. There you will see not only anomalies of each shot but the differences of each shot in a specific test of multiple sample shots.

[charlie b]

The trials of the test engineer. Trying to make sense of data that doesn't look like the models or theories

[mehavey]

What is will post will be the pressure traces and data of all the shots on each test.

Exactamundo.
Real life is messy.

[Larry Gibson]

Got some bullets cast and loaded. Waiting for a "good" day of 65-70 degrees with acceptable wind to test.

Attachment 275821

Attachment 275822

[KenH]

We're all waiting with great interest in the results. Go Larry!!! Per NOAA it looks like you've got a few days of 50°F weather for a few days. BUT - you will get some decent days.

[charlie b]

I think your shoulder is going to be sore