Black Powder Propellant Questions

[dave carver]

The FSI F100 and E60's were more cato prone due to the fact that they weree gang pressed versus automated machine made with a Mabel. The QC suffered consequently. what I'm saying gang presses were used by pyrotechnic manufacturers for centuries to make cored skyrockets, which the FSI F100 and E60 basically were. Plus the fact that longer cored motors will have less strength towards the middle-top with age and weathering issues also resulted in catos.

The original Carlisle Rock-A_Chutes were made with air hammers if you can believe that! They also suffered QC problems and hence Vern Estes designed and built Mabel.


Thermalite igniters were probably overkill for the FSI engines; it would be like using a small blasting cap which would fracture the pressed BP causing a cato. I also beleive this caused a number of catos. Electric squibs such as used in APCP are probably NOT a good idea for BP motors of any size. Did you know that you could get completely different thrust time curves depending on whether you ignited a core burner at the top or bottom?

In pyrotechnic skyrockets above where the core ends, they had a solid grain called a "heading" the length of this "heading" determined the delay of the short high thrust skyrockets. To prevent depressurization they would place a clay cap above this with a hole in it to propagate the flamefront to loose BP which was used as a burst or ejection charge as we call it today Orv Carlisle exchanged this heading made of pressed BP with a new pressed BP delay train that was formulated to make more smoke.

If you ever have seen internal drawings of pyrotechnic skyrockets and the old Coaster Cored rocket motors, or the FSI F100/E60 or Rocketflite FGH they all look identical.

HTH

Terry Dean

By "bottom" I should have said nozzle end. My mistake.

 

[bobkrech]

High explosive? BP can detonate?

CJL

BP, UN0028 is a 1.1D explosive. 49 CFR 172.101 Table

BP contains 3 megajoules per kilogram, and for comparison, the energy density of TNT is 4.6 megajoules per kilogram. BP has 65% of the explosive power of TNT.

Due to the lobbying power of NRA and the Second Ammendment, BP for small arms use is reclassified as NA0027 4.1 Flammable Solid.

Bob

 

[cjl]

BP contains 3 megajoules per kilogram, and for comparison, the energy density of TNT is 4.6 megajoules per kilogram. BP has 65% of the explosive power of TNT.

Energy content alone does not tell the full story with explosive power. The flame propagation speed is also significant. A simple road flare contains significant energy, but due to the slow release of the energy, it has effectively no explosive power at all.

TNT detonates. Its flame propagates supersonically, effectively allowing the entire quantity of explosive to go off instantly, generating a significant overpressure and shock wave. BP, at least as far as I know, cannot detonate. Instead, it simply burns quickly, creating a fireball with plenty of heat and energy, but nowhere near the overpressure or shock wave that an equivalent amount of TNT would.

 

[The EGE]

Energy content alone does not tell the full story with explosive power. The flame propagation speed is also significant. A simple road flare contains significant energy, but due to the slow release of the energy, it has effectively no explosive power at all.

TNT detonates. Its flame propagates supersonically, effectively allowing the entire quantity of explosive to go off instantly, generating a significant overpressure and shock wave. BP, at least as far as I know, cannot detonate. Instead, it simply burns quickly, creating a fireball with plenty of heat and energy, but nowhere near the overpressure or shock wave that an equivalent amount of TNT would.

Deflagration versus detonation.

I've never used the Estes E motors, and I may never unless I decide to make a 24mm cluster. They're just so much heavier than composite Es, and too low-thrust for my taste. Plus I can get E18s for the same price, and I can adjust the delays and ejection charge on them.

 

[MarkII]

Well, I have always said that I am not very well informed about any of this - the history of model rocket motors or the chemistry of propulsion (not to mention a whole lot of other technical aspects of rocketry). Just as Monty has been admonished to do his research, I would like to do some digging for my own education, too. I am not at all interested in making motors, but I want to get a good basic knowledge of the technology of solid rocket motor propulsion. I realize that this may take a fair amount of time and a good deal of study, and I am prepared to make that investment. Can anyone suggest a good place to start? I have wanted to ask this question for over a year now, but I wanted to do it in a way that communicated that I was serious. This is not a spur of the moment interest. I will never be a chemist, an engineer or a pyrotechnics maker; those aren't my goals and they aren't attainable for someone my age anyway. I just want to be informed.

Mark K.

 

[cjl]

Deflagration versus detonation.

Exactly.

I've never used the Estes E motors, and I may never unless I decide to make a 24mm cluster. They're just so much heavier than composite Es, and too low-thrust for my taste. Plus I can get E18s for the same price, and I can adjust the delays and ejection charge on them.

I don't know. As much as I like composite Es (and I do enjoy them very much), there's just something nice about the nearly 3 second burn and slow liftoff of the Estes Es. They're really easy to use and reliable too.

 

[MarkII]

Exactly.



I don't know. As much as I like composite Es (and I do enjoy them very much), there's just something nice about the nearly 3 second burn and slow liftoff of the Estes Es. They're really easy to use and reliable too.

There was a discussion of Estes E9s here last year. The bottom line was that they were great motors as long as one understood how they performed and used them in appropriate applications. We need lower thrust, long-burning motors in most impulse classes just as much as we need the pad pounders.

Mark K.

 

[cjl]

There was a discussion of Estes E9s here last year. The bottom line was that they were great motors as long as one understood how they performed and used them in appropriate applications. We need lower thrust, long-burning motors in most impulse classes just as much as we need the pad pounders.

Mark K.

Agreed. The Apogee E6s are quite nice too - the 7 second burn is truly incredible.

 

[JDcluster]

Do something smart & read some history of model rockets & history in general.
It will prevent you from making the same mistakes that others have in the past.

If you want to do it right the first time, then why keep asking questions that have already been asked before?

Another aspect of rocketry is: RESEARCH


Concentrate on what you know & expand from there...
:bangpan:


JD

What I ment was it was the minimum they could put in to provide 20.01 Ns of thrust, I'm not an idiot

 

[MarkII]

Do something smart & read some history of model rockets & history in general....

JD

Do you know any good sources for the history of model rocketry? I know the basic outlines, but I am weak on some of the details (especially on all of the types of model rocket motors that have been made over the past 50 years).

Mark K.

 

[JDcluster]

Google yielded these links:

https://launchhistory.com/

https://www.solarviews.com/eng/rocket.htm

https://www.ninfinger.org/rockets/ModelRocketry/ModelRocketry.html

I know most of it back to the mid 90's...

The book modern HP is pretty good.
I even have a copy, but the pictures are of poor photo copy quality.




JD

 

[ScrapDaddy]

Do you know any good sources for the history of model rocketry? I know the basic outlines, but I am weak on some of the details (especially on all of the types of model rocket motors that have been made over the past 50 years).

Mark K.

I was -45 years old when the 1st golden age of rocketry occured

 

[ScrapDaddy]

Agreed. The Apogee E6s are quite nice too - the 7 second burn is truly incredible.

It is a PITA that they took the D3 out of production, the 6 second burn for a 18mm motor is unbelieveable

 

[JDcluster]

Can someone please change the thread topic "PROPELLANT" is spelled incorrectly....


Thank you



JD

 

[MarkII]

Google yielded these links:

https://launchhistory.com/

https://www.solarviews.com/eng/rocket.htm

https://www.ninfinger.org/rockets/ModelRocketry/ModelRocketry.html

I know most of it back to the mid 90's...

The book modern HP is pretty good.
I even have a copy, but the pictures are of poor photo copy quality.




JD

Well, I was there for part of it during its first decade, but I only knew about Estes Industries. After that, there is this 33-year lacuna stretching from 1971 to 2004. I'm good from that point on. In particular, I am interested in the rise and fall of the smaller companies, in motor development and in the evolution of HPR. For reference, the Estes D motors had just come out when I went AWOL in '71, but the minis had not shown up yet (I just missed them).

I do have Mark Canepa's book; I have just started reading it. I have also been dreamily contemplating the catalogs at Ninfinger (oh, how I totally remember those 1967-1970 Estes catalogs) and the documents at YORS and YORP since 2004, but the archived documentation at those sites is far from complete, from what I understand.

Mark K.

 

[ScrapDaddy]

Well, I was there for part of it during its first decade, but I only knew about Estes Industries. After that, there is this 33-year lacuna stretching from 1971 to 2004. I'm good from that point on. In particular, I am interested in the rise and fall of the smaller companies, in motor development and in the evolution of HPR. For reference, the Estes D motors had just come out when I went AWOL in '71, but the minis had not shown up yet (I just missed them).

I do have Mark Canepa's book; I have just started reading it. I have also been dreamily contemplating the catalogs at Ninfinger (oh, how I totally remember those 1967-1970 Estes catalogs) and the documents at YORS and YORP since 2004, but the archived documentation at those sites is far from complete, from what I understand.

Mark K.

when you droped out of rocketry did you scrap all of your kits?

 

[Winston]

Could be that any more impulse (>28Ns) would require 29mm cases (to still be practical). Or maybe the Mabels won't handle cases longer than 3.75".

But, once they're over 30g, there's no obvious reason to stop at 36.

From looking at how little space there is left at the ejection charge end of an E9-8, I think the limiting factor was how much propellant they could fit in a 24mm 3.75" casing which they were limiting themselves to for some reason.

Quest claims these are still to be released even though they were projected for 2009:

https://www.rocketryplanet.com/content/view/2522/28/

They claim the D8 will be 24mm and the E12 and F12 28mm.

 

[Pantherjon]

Can someone please change the thread topic "PROPELLANT" is spelled incorrectly....


Thank you



JD

Done

 

[MarkII]

Done

Oh, so THAT'S what we're talking about...... :shock:

Mark K.

 

[powderburner]

Energy content alone does not tell the full story with explosive power. The flame propagation speed is also significant. A simple road flare contains significant energy, but due to the slow release of the energy, it has effectively no explosive power at all.

TNT detonates. Its flame propagates supersonically, effectively allowing the entire quantity of explosive to go off instantly, generating a significant overpressure and shock wave. BP, at least as far as I know, cannot detonate. Instead, it simply burns quickly, creating a fireball with plenty of heat and energy, but nowhere near the overpressure or shock wave that an equivalent amount of TNT would.

I don't remember where I read it but I thought BP was classified as a "low" explosive because of a relatively slow detonation wavefront velocity. It also happens to have less energy density (compared to dynamite and others) but that was sort of a secondary consideration.

Miners used to use blackpowder all the time as a true explosive. I don't know if there were specific forms (powdered as delivered, packed into a prepared cavity) that worked best for this, but it was detonated and not "burned" or "deflagrated." Gunpowder as used for cannon propellant (which did burn or deflagrate) was usually manufactured in the form of small pieces (sticks, flakes, tablets, etc) to control burn rates.

 

[cjl]

I don't remember where I read it but I thought BP was classified as a "low" explosive because of a relatively slow detonation wavefront velocity. It also happens to have less energy density (compared to dynamite and others) but that was sort of a secondary consideration.

Miners used to use blackpowder all the time as a true explosive. I don't know if there were specific forms (powdered as delivered, packed into a prepared cavity) that worked best for this, but it was detonated and not "burned" or "deflagrated." Gunpowder as used for cannon propellant (which did burn or deflagrate) was usually manufactured in the form of small pieces (sticks, flakes, tablets, etc) to control burn rates.

Are you sure that mining black powder detonated? You can generate significant overpressures without detonation. As for how to get the most explosive punch out of it? My guess would be that it was finely powdered - the flame propagates in the spaces between grains much faster than it does within the grains itself, so extremely fine powdered BP can make quite a bang.

 

[ben_ullman]

I cant remember where I read this or from who I may heard it but I somehow remember that 4.5lbs (its a majic number like 4.56765lbs or something) on up of 4F BP will detonate.

Ben

 

[cjl]

I cant remember where I read this or from who I may heard it but I somehow remember that 4.5lbs (its a majic number like 4.56765lbs or something) on up of 4F BP will detonate.

Ben

Why would flame propagation velocity be quantity dependent?

 

[ScrapDaddy]

Why would flame propagation velocity be quantity dependent?

Some thing don't work in small scale, for an example , when the mythbusters lit a small portion of fabric covered in ******and ***** it didn't work (hindenburg episode) however as the scale slowly increased the propagation of flame and burning increased, for example light a small square of toilet paper with a match, then light a box of toilet paper with a match.

 

[powderburner]

Why would flame propagation velocity be quantity dependent?

Flame propagation is a different phenomenon.

Detonation is induced by a travelling pressure wave. Detonation velocities are typically 10 to 100 times faster than combustion.

It's a whole different critter.

 

[cjl]

Flame propagation is a different phenomenon.

Detonation is induced by a travelling pressure wave. Detonation velocities are typically 10 to 100 times faster than combustion.

It's a whole different critter.

True enough. I still don't see how BP would detonate though (and I might be completely wrong on this - I haven't studied explosives much at all).

 

[jsdemar]

True enough. I still don't see how BP would detonate though (and I might be completely wrong on this - I haven't studied explosives much at all).

BP has a fairly large critical diameter to cause a true detonation, quite a bit larger than a practical BP rocket motor. But, in confined spaces (under pressure) the deflagration will appear to "function by explosion". Critical diameter for APCP is anywhere from a meter to several meters, depending on sensitivity. As a comparison, the critical diameter of a "real" explosive is around a cm or so.

-John

 

[shockie]

4F vs !F grain size BP will burn faster to slower... but grain size is not an issue in BP model rocket motors; what is important is density that the BP is pressed too. Current industry practice is around 1.7 g/cc cubed. BP pressed to this density results in the pressed Bp grain becoming desensitized somewhat to the likelihood of explosion. This is called Dead-Pressing (or pressure desensitization) which is a well known phenomenon in solid explosives,
(such as hydraulically pressed black powder) which occurs
when all of the porosity (the potential hot spot sites) is compressed out of the explosive without igniting hot spots, resulting in a void less material that can
not be shock initiated.

This is why BP model rocket propellant grains are inherently safe

In addition, BP pressed to 1.7g/cc by hydraulics result in a form of plastic flow.

HTH

Terry Dean

 

[bobkrech]

Energy content alone does not tell the full story with explosive power. The flame propagation speed is also significant. A simple road flare contains significant energy, but due to the slow release of the energy, it has effectively no explosive power at all.

TNT detonates. Its flame propagates supersonically, effectively allowing the entire quantity of explosive to go off instantly, generating a significant overpressure and shock wave. BP, at least as far as I know, cannot detonate. Instead, it simply burns quickly, creating a fireball with plenty of heat and energy, but nowhere near the overpressure or shock wave that an equivalent amount of TNT would.

In powdered form, BP burns rapidly and will eventually undergo a DDT (deflagation to detonation transition). That's when BP can be a high explosive. Once pressed and consolidated, the burn rate is much slower since the surface area is much lower.

TNT can burn and not detonate below some quantitity/size limit. Under normal circumstances in pound quantities, you need a detonator to get it to go high order.

It's all about the energy transfer process.

Bob

 

[JDcluster]

Try more like 50lbs or more....That IS why you need a permit when buying & storing BP more than 50lbs. It becomes unstable.


JD

I cant remember where I read this or from who I may heard it but I somehow remember that 4.5lbs (its a majic number like 4.56765lbs or something) on up of 4F BP will detonate.

Ben