I would have to know a lot more about the test apparatus and the protocols of the experiment to even start to believe that figure demonstrates a real life, reproducible relationship that is linear over that range of OAL. There is zero chance I would rely on that.
Bullet Setback Overpressure Calculation
- Thread starter Hartkopf
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I would have to know a lot more about the test apparatus and the protocols of the experiment to even start to believe that figure demonstrates a real life, reproducible relationship that is linear over that range of OAL. There is zero chance I would rely on that.
CQB45ACP
Member
So clearly my idea is a bad one
QUICKLOAD would agree:
5th-Order Polynomial
That's more like it! Fitting curves to data sets is good, clean fun!
Well, I would say that it just wouldn't give you meaningful results in terms of telling you what you want to know.
fxvr5
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I'm curious, combustion of what?
fxvr5
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That graph is from their reloading manual #3. They report pressures in that manual, so presumably they were using SAAMI spec methods. But the only way to know for sure is to ask them. Now, Western Powders handles all data for Ramshot powders.
My lab group had a wide variety from smouldering combustion in a variety of solid materials including one guy who did his PhD work on smouldering combustion in micro-gravity; combustion inside piston/cylinders, shock tube reacting flows, etc. you name it. Different investigators focused on different aspects of each, whether it be heat transfer, fluid dynamics, thermodynamics, chemical reactions in the flow, etc. and of course there was always some level of overlap of all of those on any given project.
Under my first professor, the teams were split into electric propulsion in rocket engines (seeding flows with ionized species and then using electric fields to accelerate the reacting exhaust) and combustion instabilities in ramjet engines. I was on the latter of those two teams. I remember giving one of my sisters a tour of the lab and explaining what we were doing and her response was, "You are a rocket scientist!'
After that, I moved to a professor who focused on fire science and I did my MS project using a pair of coincident lasers (He-Ne and Argon Ion) to measure carbon particulate (soot) volume fraction in pool fire flames for a variety liquid fuels. The reason for wanting to know those values is that the carbon particulate inside of the reacting mixture is the primary source of the radiation heat transfer from the flames, which helps in understanding, modeling, and predicting the rates at which fires will grow and propagate.
fxvr5
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You made my head explode. I'm almost sorry I asked.
HAHA! Sorry . . . I don't get to talk about it much at this point in life and when you asked, I just did a memory dump.
I did have an incident in my lab during which I caught on fire. I was extinguishing a circular pan that was about 60cm in diameter with burning acetone in it by snuffing with a lid, but I removed the lid a little too soon and dragged a few ounces of the acetone onto the floor and the front my shirt. It got exciting for a moment because I wanted to drop and roll, but the floor was on fire, which made that seem like a bad idea. Fortunately, the acetone was vaporizing and burning so fast that it burned out before it could hurt me. My shirt (it was cotton) was singed black in spots, but no injury. I was able to use a handy fire extinguisher to deal with the mess on the floor. I was a little shaken after all of that and went home. The next day, the lab manager was really angry because I didn't report it to him before I left. He had no concern over whether I was okay, just that I hadn't followed his rules to the letter in that immediate time period. Nice priorities!
CQB45ACP
Member
Even when I don’t understand, I enjoy hearing or reading someone discussing their work (or hobby) with enthusiasm. Your’s passed every test.
I similarly enjoy reading reloading discussions here about things I’ll never begin to understand.
I think we're going to get along okay!
Blue68f100
Member
I was a lab tech for a R&D center for 20+ yrs. I always had fun when one of the new phd's prediction was way off. We always had side bets on what would happen when we took a test sample to destruction. Most learned not to wager against me
because all my experience would beat them. One of my orders was to keep them from killing them selves or someone ease. It came closer than I liked one time, evacuated the building for 2 hrs till all the poisonous gas was scrubbed. At least he had enough since to open the valve in a lab designed to handle the gas, fully monitored, and containment. My boss and manager was not very happy with the event. The manager was on a conference call with a VP at the time of the event.High press is something you really have to be careful with. I worked with gas pressures to 30kpsi, volume of ~ 1 cuft. I was told when they went to design my test bunkers, a catastrophic failure was the equivalent of 5 sticks of TNT going off. The cells were designed not take damage and contain the gas if needed. The best bomb shelter made.
Since gun powder is not linear it makes it harder to predict.
When the data disagrees with the theory,
. . . so much the worse for the data.
(old experimental physicist meme)
I was a lab tech for a R&D center for 20+ yrs. I always had fun when one of the new phd's prediction was way off. We always had side bets on what would happen when we took a test sample to destruction. Most learned not to wager against me
High press is something you really have to be careful with. I worked with gas pressures to 30kpsi, volume of ~ 1 cuft. I was told when they went to design my test bunkers, a catastrophic failure was the equivalent of 5 sticks of TNT going off. The cells were designed not take damage and contain the gas if needed. The best bomb shelter made.
Since gun powder is not linear it makes it harder to predict.
Indeed! I remember watching one of the teams pressure test a high pressure combustion chamber by pumping water into it and gradually increasing the pressure until they hit what they needed to verify. A less experienced and aware person might not understand why you use an incompressible fluid like water for that instead of a compressible fluid (i.e. a gas like air). When you compress gases to high pressures they store extraordinary amounts of energy. If the vessel fails, you would then have a bomb instead of a box squirting jets of water at relatively low velocities. Splish splash is preferable to KABOOM!
I've never heard that, but I like it. I would tweak it a little though to say when the data disagrees with the hypothesis (unless I am grossly misunderstanding what the meme means).
Once something is a real theory, it means that it has a large body of data accumulated by multiple investigators that supports the hypothesis that became the theory (because of the evidence supporting it). I cringe a little when people use the word "theory" or "theoretically" when in almost all cases, what they really mean is "hypothesis" or "hypothetically."
ALERT! PACHYDERM PEDANTRY! ALERT!
AJC1
Member
We used to test air tanks filled with water and pressurized with a grease gun.... I learned that about 8 years old....
Well done!
GeoDudeFlorida
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The problem is predictive analytics is the new-age snake oil. Some folks will believe the strangest things - entirely counter intuitively and against the documented evidence - with all their heart if it’s printed in a table.
If computer models were accurate Miami would have been under water 20 years ago.
The problem is predictive analytics is the new-age snake oil. Some folks will believe the strangest things - entirely counter intuitively and against the documented evidence - with all their heart if it’s printed in a table.
If computer models were accurate Miami would have been under water 20 years ago.
You make a strong point!
But then I believe you're talking about models that almost universally start with a pre-conceived outcome and are tailored to point to that outcome rather than objective tools built for objective investigation of hypotheses.
Unfortunately, in that field of study, there is little or no funding for building objective models whose results may not support the desired outcome. If I ever win a huge lottery, maybe I'll work on it myself and hire a few honest people to collaborate. That's actually a really good idea now that I've read what I just typed!
`Could NOT have said it better myself.
(!)For nearly all of recorded history, theory was that men & women were attracted to one another.
Now we know it was really just warped space.
GeoDudeFlorida
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If honesty paid politicians would live in poor houses.
I’m not trying to discourage anyone. I’m just reminding everyone that predictive analytics are defined by very narrow standards. They should only be applied in kind. A simple powder lot change alters the outcome. Maybe it’s negligible; then again, maybe not. Only a carefully constructed experiment can say.
...that includes a chronograph in the setup.
GeoDudeFlorida
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Yes and no. I work in the medical field as a programmer analyst. We’re VERY WELL funded. To the tune of billions - as an industry. Me personally not so much.
When dealing with diseases like MD and cancer - where the patient is the variable - the number of corrective measures for data set is staggering.
My dad was a physicist with the space program. He’s told me many times they were just guessing about so many assumptions made and they got lucky more often than not.
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