anybody know in general what the burn rate is for typicial Estes type BP propellant? and then compare this burn rate to say APCP burn rate? in mm/sec please if possible
Does the density of the proepllant mixture play a role in the propellant burn rate? For example, I assume that Estes BP is pressed into their casing at a known pressure? and this produces a propellant slug that has a more or less uniform density? I also assume they are pressed wet....and then dryed/cured by letting the water in them evaoporate off? I hope this makes sense...
2 atm. about 10-12mm/s
3atm: about 14-15mm/s
5atm about 18-19mm/s above about 5atm-7atm the slope drops notably.
10 atm: about 20mm/s
30atm: about 24mm/s
The word "about" is important. Ballistics can vary from lot to lot and other variables come into play as well per below.
APCP burn rate? From < 4 mm/s to > 25 mm/s depending on several variables. Black powder is a relatively "fixed" composition. APCP is not.
It is a pressed composition thus full of microporosity and ballistics depend heavily on compaction pressure.
For example, I assume that Estes BP is pressed into their casing
Yup.
and this produces a propellant slug that has a more or
Yup, more or less. There are density gradients in pressed compositions. Unroll one and take a look.
I also assume they are pressed wet....and then
Humid would be a better word. They can be and are fired immediately after pressing.
It is roughly double to triple the burn rate and has a low rate exponent (rate vs pressure) but a notable increase in ISP with pressure, sometimes 160 ISP or so.
jerry: have you seen or heard of that new BP substitute that ATK Thiokol has produced? its called Moisture Resistant BP Substitute? They replace the charcoal with phenolphthalein, remove the sulfur,add some Potassium Perchlorate as an additional oxidizer in conjunction with the Potassium Nitrate and then add ethyl Cellulose resin as a binder? Its says the Pressure exponent of this mixture is ~ 0.33 versus 0.20 for traditional BP..
david: I don't see why it couldn't be used as an ejection charge or even a delay train for that matter, as they say by adjusting the ingredients, the mixture can be "tuned"....thats their word.....
On Thu, 16 Oct 2003 22:17:24 GMT, Jerry Irvine is alleged to have written:
Knowing what phenopthalein was used for (up until a few years ago), the mental image I got from your suggestion that you might "try it in [your] extruder" is not one that I wanted to have. Excuse me for a moment -- I need to go scrub out my frontal lobes with a wire brush....
If I'm not mistaken, this compound is similar to either Clean Shot, Clear Shot or Triple 7. Given the higher pressure factor and the absence of sulfur I'd bet it's pretty close to Hodgdon's Triple 7 propellant. I've been using this lately in my 45-90 Sharps rifle. I get about 200 fps higher velocity over BP with the same volume charge.
If you ever taken a Chemistry class, at some point, you'll come across phenolphthalein in liquid form, is used as a base indicator.
One of my classmates I guess knew what the other use of it was and added a some to the teachers coffee when he wasn't looking. He wasn't very happy afterwards. Silly High School pranks.
On Fri, 17 Oct 2003 14:28:31 GMT, "Bruce Canino" is alleged to have written:
I'll bet he wasn't. I imagine he wasn't expecting weak bad Irish coffee. Or, perhaps, weak Irish coffee made with "rubbing alcohol".
Phenopthalein indicator solution is typically made at a concentration of 0.5% to 1%, in a 50% to 95% alcohol solution. Sometimes they use ethanol (typically denatured with methanol), and sometimes they use isopropynol.
Assuming for the moment that you used the *safest* variety of alcohol (entirely by accident), containing 50% ethanol, and no methanol. Let's also assume that you used the maximum concentration of phenopthalein, which is 1%. While it was available, the recommended dose was 50-200 mg. Let's assume 50mg would be effective when accompanied by coffee....
OK... 50mg at 1% means 5000mg (aka 5g) of solution. So, about 5 ml of a roughly water-density liquid, half of which is pure ethyl alcohol.
50% alcohol is 100 proof, and 5 ml is about a teaspoon. So, roughly comparable to a *tiny* shot of really bad booze.
I'd be mad, too. Not only did you give him the runs, you ruined a perfectly good chance to make Irish coffee by using really bad, contaminated booze to do it, and nowhere near enough of it!
- Rick "Back of the envelope recipes, Inc." Dickinson
I use phenolphthalein indicator on a daily basis to titrate Hydrochloric and Nitric acid solutions at work. Don't let the guys I work with know phenolphthalein's 'other' use, or they'll be spiking my pop with it! ;-)
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