Black Powder Propellant Questions

[ScrapDaddy]

#1 why don't they cut slots in BP propelent? does it have anything to do with the structure or how it burns linerly?It burns faster than composite propelent so wouldn't this create a higher thrust?

#2 Why don't you see BP motors larger than an E? Is it the brittleness of the stuff?

[GrossApproximator]

Regarding your second question, I'm pretty sure that larger black powder motors were at once available, but they were phased out due their brittleness (unseen cracks cause CATOs I think) and because the composite motors produce so much more power per unit weight.

[bcanino]

#1 why don't they cut slots in BP propelent? does it have anything to do with the structure or how it burns linerly?It burns faster than composite propelent so wouldn't this create a higher thrust?

BP is press in the motor tube itself which makes it hard cut after the fact. I don't think slot burn design works well with BP motors. There has been core burning BP motors before, but they are labor intensive and are more prone to cato if not stored / handle properly.

AP is pressed in a liner, it is easier to cut a slot in the liner.

#2 Why don't you see BP motors larger than an E? Is it the brittleness of the stuff?

That have been BP F and above, and Quest says they will have a F BP soon, but it hard to press the amount of BP for E and above. Also BP E's and above (Even Estes have to be shipped hazmat which add to the price)

[cjl]

#1 why don't they cut slots in BP propelent? does it have anything to do with the structure or how it burns linerly?It burns faster than composite propelent so wouldn't this create a higher thrust?

#2 Why don't you see BP motors larger than an E? Is it the brittleness of the stuff?

1) Because they don't need to. It would be a huge manufacturing headache, and create extremely short burn motors. They would also have to completely change the way that the delays were done. It would also cause greater risks of cracks in the BP and catos. Besides, some people like longer burn motors.

2) BP isn't very efficient, so the motors would be very large (physically). This would put them at high risk of cato due to propellant cracking. Besides, it wouldn't be any cheaper than AP motors of similar size, and why would you buy a BP F motor rather than an AP F motor (aside from the novelty factor)?

[bobkrech]

#1 why don't they cut slots in BP propellant? does it have anything to do with the structure or how it burns linearly?It burns faster than composite propellant so wouldn't this create a higher thrust?

#2 Why don't you see BP motors larger than an E? Is it the brittleness of the stuff?

While there a much larger BP rocket motors made by fireworks folks than E class Estes motors, they are made by hand as opposed to the automated machine made Estes motors. Furthermore big BP motors are regulated explosive devices requiring an explosives permit, and this alone drives the larger hobby motor market toward APCP. (Any BP motor with more than 62.5 grams of BP is a regulated device requiring an explosives permit.)


Black powder motors are quite different than composite motors.

Black powder rocket motors are made from compressing black powder in a heavy motor tube as opposed to APCP propellant grains that are simply cast and cured in a thin walled casting tube.
Black powder burns at a much faster than APCP, typically about 1" per second versus 0.2" to 0.4" per second for composites, but they are not efficient in converting propellant weight to thrust. The specific impulse of BP motors is typically between 60-80 seconds whereas hobby APCP has a typical specific impulse between 170-230 seconds.
On an equal propellant weight basis, you get 3 times more thrust from APCP than you get from BP.
BP motors are more dangerous to make than APCP motors because BP can explode when compressed in manufacturing whereas APCP will not ignite in manufacturing unless there is a major screwup in processing safety practices.
Bob

[ScrapDaddy]

That have been BP F and above, and Quest says they will have a F BP soon, but it hard to press the amount of BP for E and above. Also BP E's and above (Even Estes have to be shipped hazmat which add to the price)

GRrr tell me about it Did estes purposely put 5.8 grams to much in JUST to incur a HAZMAT fee?

[MarkII]

For the first couple of decades, Estes Industries made core-burning black powder motors. The celebrated (and now very rare) Estes B14-0 (http://www.ninfinger.org/rockets/nostalgia/68estp52.html) motor was the standard first stage booster in such rockets as the Farside-X because it was unsurpassed in getting 3-stagers and large 2-stagers up and off the launch pad. They were a real PITA and dangerous to make, though, which is why they were discontinued by the Damon-era Estes. For a number of years, Estes then produced a B8 motor, which had a pronounced dimple in the propellant face rather than an actual core. The high-thrust 18mm motors were eventually phased out and the big D motors became Estes Industries' heavy load lofter. Because of the safety issues with making them, I doubt that we will ever see cored BP motors again.

To go along with what Bob said, black powder doesn't scale up well to high power sizes. There were some baby HPR motors made with BP for awhile, but they were quite massive compared to AP motors that delivered the same or greater impulse. If you ever get the chance, hold an Estes E9 in one hand and an Aerotech E30 in the other and compare the weights of these two motors. The weight of the propellant in the Estes motor is 36 grams, while the the propellant in the AT motor weighs 19 grams. Yet the Estes E9 has a total impulse of just about 28 N-s., while the much lighter AT E30 has a total impulse of nearly 40 N-s.

With that being said, though, there is great interest in the mid-power (D, E and F) black powder motors that Quest plans to eventually release.

Mark K.

[ScrapDaddy]

For the first couple of decades, Estes Industries made core-burning black powder motors. The celebrated (and now very rare) Estes B14-0 (http://www.ninfinger.org/rockets/nostalgia/68estp52.html) motor was the standard first stage booster in such rockets as the Farside-X because it was unsurpassed in getting 3-stagers and large 2-stagers up and off the launch pad. They were a real PITA and dangerous to make, though, which is why they were discontinued by the Damon-era Estes. For a number of years, Estes then produced a B8 motor, which had a pronounced dimple in the propellant face rather than an actual core. The high-thrust 18mm motors were eventually phased out and the big D motors became Estes Industries' heavy load lofter. Because of the safety issues with making them, I doubt that we will ever see cored BP motors again.

To go along with what Bob said, black powder doesn't scale up well to high power sizes. There were some baby HPR motors made with BP for awhile, but they were quite massive compared to AP motors that delivered the same or greater impulse. If you ever get the chance, hold an Estes E9 in one hand and an Aerotech E30 in the other and compare the weights of these two motors. The weight of the propellant in the Estes motor is 36 grams, while the the propellant in the AT motor weighs 19 grams. Yet the Estes E9 has a total impulse of just about 28 N-s., while the much lighter AT E30 has a total impulse of nearly 40 N-s.

With that being said, though, there is great interest in the mid-power (D, E and F) black powder motors that Quest plans to eventually release.

Mark K.

Well I came up with the idea of a core BP motor without any knowlage of the B-14, if estes thought of it and I thought of it 30 years later, looks Luke I have a brain!

[bobkrech]

GRrr tell me about it Did estes purposely put 5.8 grams to much in JUST to incur a HAZMAT fee?
ScrapDaddy

A Jr. Mad Scientist should be able to do, or learn how to do, their own research on the web. :y: And maybe someday become a real Mad Scientist like me :eek:, which is how I've earn my keep for the last 39 years. :cool:


:confused: You can search this forum, the TRF 1 archives, or Google to find answers for many of the questions you are asking, and in the process you will learn how a real Mad Scientist gathers the information he needs to do his job. :madnote: +:pop:

If you are confused :confused2:, or don't understand something you find :bang:, there's lots of folks here who can help you out :wave:, but you really should do a bit of homework on your own before you ask a bunch of questions. :impatient:

:cheers:

Bob :2::dark:

[ScrapDaddy]

ScrapDaddy

A Jr. Mad Scientist should be able to do, or learn how to do, their own research on the web. :y: And maybe someday become a real Mad Scientist like me :eek:, which is how I've earn my keep for the last 39 years. :cool:


:confused: You can search this forum, the TRF 1 archives, or Google to find answers for many of the questions you are asking, and in the process you will learn how a real Mad Scientist gathers the information he needs to do his job. :madnote: +:pop:

If you are confused :confused2:, or don't understand something you find :bang:, there's lots of folks here who can help you out :wave:, but you really should do a bit of homework on your own before you ask a bunch of questions. :impatient:

:cheers:

Bob :2::dark:

Just taking a stab here but I'm guessing it was the mininmum amount of BP they could put in and still quallify as an "E"

[shreadvector]

Just taking a stab here but I'm guessing it was the mininmum amount of BP they could put in and still quallify as an "E"
NO. Once again you are proving that you have read very little and done little searching. You obviously want to learn, but you seem to want us to "spoon feed" you or to chew your food for you.

ANY basic information on Model Rockets shows the power ranges for the different letter classes. ANYTHING over 20.01 Newton-seconds and up to 40.00 N-s is an E motor. You can make an E motor with 21 N-s or 27 or 35 or 40.

I suspect that Estes chose the new casing size (1 inch longer than the D12 and 1/4 inch longer than the not-so-good E15 from a few years earlier). They then determined how much maximum propelant and delay time they could fit in using a machine.

As a matter of fact, they may have determined the casing length by testing longer versions with more propellant and determining when they got "too long" and experienced casing erosion to the point of being too thin. They then selected the longest safe length and that determined the maximum propellant.

Again, that's all "maybe". Maybe someone can contact them directly and ask them as they would know?

[ScrapDaddy]

NO. Once again you are proving that you have read very little and done little searching. You obviously want to learn, but you seem to want us to "spoon feed" you or to chew your food for you.

ANY basic information on Model Rockets shows the power ranges for the different letter classes. ANYTHING over 20.01 Newton-seconds and up to 40.00 N-s is an E motor. You can make an E motor with 21 N-s or 27 or 35 or 40.

I suspect that Estes chose the new casing size (1 inch longer than the D12 and 1/4 inch longer than the not-so-good E15 from a few years earlier). They then determined how much maximum propelant and delay time they could fit in using a machine.

As a matter of fact, they may have determined the casing length by testing longer versions with more propellant and determining when they got "too long" and experienced casing erosion to the point of being too thin. They then selected the longest safe length and that determined the maximum propellant.

Again, that's all "maybe". Maybe someone can contact them directly and ask them as they would know?

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]

Just taking a stab here but I'm guessing it was the mininmum amount of BP they could put in and still quallify as an "E"Someone (it might have been Fred S.) discussed the origin of the Estes E9 in another thread sometime in the past month. I can't find the post right now (the Search function here is very limited in power), but as I recall, the post said that the E9 was a "detuned" version of the very cato-prone Estes E15. Estes started using a different shape of nozzle for the motor in order to improve its reliability. This changed the motor's performance, causing it to be redesignated as an E9.

Also, as previously discussed, black powder is not a particularly efficient propellant (effective, but not efficient). In other words, it is rather dense and heavy for the amount of impulse it delivers. It requires more than 30 grams of BP to produce a motor with E impulse. Motors with more than 30 grams of propellant require hazmat shipping, hence the extra charge. No one can produce a black powder E motor that contains less propellant. Estes has 50 years of experience in producing black powder model rocket motors; they are the experts. If it were possible to manufacture black powder E motors that contained less than 30 grams of propellant, Estes would be doing it, because it would enable the company to sell a heck of a lot more of them than they do now.

Mark K.

[plano-doug]

If it were possible to manufacture black powder E motors that contained less than 30 grams of propellant, Estes would be doing it, because it would enable the company to sell a heck of a lot more of them than they do now.Mark,

According to the NAR spec sheet on the E9, it has 35.8g of propellant and 27.87Ns of impulse which amounts to 0.78Ns per gram of BP. Thus, 30g would yield about 23Ns, a baby E (assuming no change in Isp with the smaller load). So they can do it.

But they probably thought 23Ns was kinda wimpy for an E. My guess is that they were trying to get more whoosh - as much as what they deemed practical - and that's how they arrived at the current motor.

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.

Doug

.

[dave carver]

For cored BP motors look up FSI F100 or E60's. I went through 9 F100's before I discovered the tendency, in almost equal porportions, 1) to blowup on the pad, 2) go up 10-20 feet then blowup, 3) take a rocket for a ride of thousands of feet. Unlike the composits that are lit at the delay end of the core the FSI motors were issued with a short piece of Thermalite(not thermite). You were instructed to take the outer wrappings of fibre and flair the wires out far enough to hold it in the nozzle. Thermalite is made with a wire core then about 1/8th inch in diameter core of Thermalite, 7 strands of wire wrapped around that and a sisel(fiberous rope stranding) wrapped around it all. the piece was about 2" long and you'd just connect the leads one above the other, the hot wire between the leads igniting the Thermalite.

You must have a LEUP for Thermalite because it is listed as an explosive fuseing material.


...But they blew up....a lot:p

[ScrapDaddy]

How on earth did those motors get certifyed?

[luke strawwalker]

GRrr tell me about it Did estes purposely put 5.8 grams to much in JUST to incur a HAZMAT fee?

No... it takes a certain amount of BP to do the job...

Want a motor with less BP-- Get a D12!

Even the Saturn V wasn't as big as it was just to be cool-- it had to be that big to hold enough fuel to do the job...

Later! OL JR :)

PS... if you're really interested, look up the old FSI F100 motors. FSI (Flight Systems, Inc.) made other BP motors in the E and F range as well...

[luke strawwalker]

Well I came up with the idea of a core BP motor without any knowlage of the B-14, if estes thought of it and I thought of it 30 years later, looks Luke I have a brain!

The FSI motors were cored too.

The Estes B14's were drilled after the motor was pressed... kinda dangerous, running a spinning drill bit chewing it's way through compressed black powder!

I think the FSI motors were pressed around a tapered mandel giving a deep 'core burner' profile, but that's anecdotal and before my time... I had FSI catalogs when I was in high school but couldn't afford their stuff at the time... :)

OL JR :)

[luke strawwalker]

Someone (it might have been Fred S.) discussed the origin of the Estes E9 in another thread sometime in the past month. I can't find the post right now (the Search function here is very limited in power), but as I recall, the post said that the E9 was a "detuned" version of the very cato-prone Estes E15. Estes started using a different shape of nozzle for the motor in order to improve its reliability. This changed the motor's performance, causing it to be redesignated as an E9.

Also, as previously discussed, black powder is not a particularly efficient propellant (effective, but not efficient). In other words, it is rather dense and heavy for the amount of impulse it delivers. It requires more than 30 grams of BP to produce a motor with E impulse. Motors with more than 30 grams of propellant require hazmat shipping, hence the extra charge. No one can produce a black powder E motor that contains less propellant. Estes has 50 years of experience in producing black powder model rocket motors; they are the experts. If it were possible to manufacture black powder E motors that contained less than 30 grams of propellant, Estes would be doing it, because it would enable the company to sell a heck of a lot more of them than they do now.

Mark K.

Wild thought totally out of the blue...

I wonder what a BP motor that contained ground up bits of APCP in it would do... sort of a solid hybrid motor. The BP would provide the pressure and temperature to ignite and sustain the embedded grains of APCP, like a binder of sorts... and of course using BP as the "binder" would allow the motor to be ignited like regular BP end burning motors, as well as allowing for 'regular' BP type staging... :) The mixture would use the 'souped up' high-ISP APCP to raise the performance while greatly reducing the amount of needed BP to a minimum necessary. I'd bet they could even be designed to be cored...

Probably a serious brain fart on my part, but wonder if it's ever been tried???

OL JR :)

[ScrapDaddy]

Wild thought totally out of the blue...

I wonder what a BP motor that contained ground up bits of APCP in it would do... sort of a solid hybrid motor. The BP would provide the pressure and temperature to ignite and sustain the embedded grains of APCP, like a binder of sorts... and of course using BP as the "binder" would allow the motor to be ignited like regular BP end burning motors, as well as allowing for 'regular' BP type staging... :) The mixture would use the 'souped up' high-ISP APCP to raise the performance while greatly reducing the amount of needed BP to a minimum necessary. I'd bet they could even be designed to be cored...

Probably a serious brain fart on my part, but wonder if it's ever been tried???

OL JR :)

you know last staturday I was thinking the same thing But Mixing AcAP and BP is hazardus, as the 2 substances are not compatible

[MarkII]

Wild thought totally out of the blue...

I wonder what a BP motor that contained ground up bits of APCP in it would do... sort of a solid hybrid motor. The BP would provide the pressure and temperature to ignite and sustain the embedded grains of APCP, like a binder of sorts... and of course using BP as the "binder" would allow the motor to be ignited like regular BP end burning motors, as well as allowing for 'regular' BP type staging... :) The mixture would use the 'souped up' high-ISP APCP to raise the performance while greatly reducing the amount of needed BP to a minimum necessary. I'd bet they could even be designed to be cored...

Probably a serious brain fart on my part, but wonder if it's ever been tried???

OL JR :)I suspect that you have outlined a recipe for a cato. I really don't know very much about such things, but I just have this hunch... :eek:

The motors are the FSI products that I know the least about. I have never even seen any, let alone bought or flown them. I saw a post a couple of years ago that said that the F100s really needed to be lit from the top of the core, just like AP motors, and that they were much more reliable when they were ignited in that manner. In light of what Dave just said, though, it looks like you would have needed to supply your own igniter in order to do that. If the igniters were 2" long, how deep was the F100's core?

Mark K.

[bobkrech]

Just taking a stab here but I'm guessing it was the minimum amount of BP they could put in and still qualify as an "E"
SD

I thought my reply was pretty clear: you need to do your homework before you post or speculate.

If you searched TRF for hazmat fees, you will find out why you have to pay a hazmat fee on an Estes E motor. (Hint: With a written permit from the USPS you can mail rocket motors containing not more than 30 grams of propellant. Shipping rocket motors of any size always incurs a DOT hazmat fee.)

If you searched TRF for explosives permits, you will find that rocket motors that contain not more than 62.5 grams of propellant are exempt from the federal requirement of having a BATFE explosives permit. (NAR/TRA challenged BATFE in court on their ruling that APCP was an explosive, and won, so large APCP motors are not regulated, but large BP motors still are.)

There is no economically viable hobby rocket motor market for a regulated BP motors with over 62.5 grams of propellant when APCP motors perform 3 times better, cost less and are not regulated, so that's why you can find them.

Bob

[bobkrech]

Wild thought totally out of the blue...

I wonder what a BP motor that contained ground up bits of APCP in it would do... sort of a solid hybrid motor. The BP would provide the pressure and temperature to ignite and sustain the embedded grains of APCP, like a binder of sorts... and of course using BP as the "binder" would allow the motor to be ignited like regular BP end burning motors, as well as allowing for 'regular' BP type staging... :) The mixture would use the 'souped up' high-ISP APCP to raise the performance while greatly reducing the amount of needed BP to a minimum necessary. I'd bet they could even be designed to be cored...

Probably a serious brain fart on my part, but wonder if it's ever been tried???

OL JR :)

Why would you do this? The manufacturing processes for a BP motor are totally different than an APCP motor.

BP is a sensitive 1.1D high explosive in the quantities use in motor manufacturing. Handling and pressing BP is dangerous business, and several folks have been killed and/or seriously injured producing them. The great advantage is that with the proper automated equipment, you can make 10-12 motors a minute.

APCP is not explosive but the starting materials are highly flammable and can deflagrate or possibly explode during the initial portions of the manufacturing process, however once the materials are wetted and mixed, they are difficult to ignite by accident. APCP can be mixed in large batches and hand or machine packed into casting tubes to make fuel grains the size of which is determined by your budget.

BP is cheap. Adding expensive AP to it would not be worth the expense of a BPAP motor. APCP is more expensive than BP, but makes a more energetic propellant. It would defeat the purpose of APCP to downgrade it's performance by adding BP.


you know last Saturday I was thinking the same thing But Mixing AcAP and BP is hazardous, as the 2 substances are not compatible

How did you determine that AP and BP are incompatible? (They're not, but you wouldn't mix them for the reasons stated above.)

Bob

[cjl]

BP is a sensitive 1.1D high explosive in the quantities use in motor manufacturing.

High explosive? BP can detonate?

[dave carver]

I suspect that you have outlined a recipe for a cato. I really don't know very much about such things, but I just have this hunch... :eek:

The motors are the FSI products that I know the least about. I have never even seen any, let alone bought or flown them. I saw a post a couple of years ago that said that the F100s really needed to be lit from the top of the core, just like AP motors, and that they were much more reliable when they were ignited in that manner. In light of what Dave just said, though, it looks like you would have needed to supply your own igniter in order to do that. If the igniters were 2" long, how deep was the F100's core?

Mark K.

...try lighting the top and you have insta-cato, the deal with lighting the bottom of the motor was to slow the propagation(sp) of the flame front. They were true core burners with the core extending from the nozzle to the delay element. Silver Streaks are another core burning BP motor.

[dave carver]

How on earth did those motors get certifyed?




What certification? This "certification" crap is a fairly recent developement in the history of rocketry. To top it off we imposed it upon ourselves, no one told us to do it. NAR started doing certifications to insure that a C motor was a C and so on for their competetions.

[Bazookadale]

What certification? This "certification" crap is a fairly recent developement in the history of rocketry.
Not sure what you mean by recent - the NAR was certifying motors in the early '60s, maybe even in the '50s. And yes FSI products did manage to get certified while some others didn't - they were able to pass S&T tests. I for one fell the testing and certification of motors is one of the best things the NAR does

[jdbectec]

...try lighting the top and you have insta-cato, the deal with lighting the bottom of the motor was to slow the propagation(sp) of the flame front. They were true core burners with the core extending from the nozzle to the delay element. Silver Streaks are another core burning BP motor.

Years ago Bob Kaplow showed me how to reliabley ignite an FSI core-burner, from the bottom with an Estes igniter just touching the propellant. A little tape to hold it in place(not covering the nozzle!). Works like a charm!

I don't recall having a Cato using his method.

[shockie]

For cored BP motors look up FSI F100 or E60's. I went through 9 F100's before I discovered the tendency, in almost equal porportions, 1) to blowup on the pad, 2) go up 10-20 feet then blowup, 3) take a rocket for a ride of thousands of feet. Unlike the composits that are lit at the delay end of the core the FSI motors were issued with a short piece of Thermalite(not thermite). You were instructed to take the outer wrappings of fibre and flair the wires out far enough to hold it in the nozzle. Thermalite is made with a wire core then about 1/8th inch in diameter core of Thermalite, 7 strands of wire wrapped around that and a sisel(fiberous rope stranding) wrapped around it all. the piece was about 2" long and you'd just connect the leads one above the other, the hot wire between the leads igniting the Thermalite.

You must have a LEUP for Thermalite because it is listed as an explosive fuseing material.


...But they blew up....a lot:p

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

[RoyAtl]

Wild thought totally out of the blue...

I wonder what a BP motor that contained ground up bits of APCP in it would do... sort of a solid hybrid motor. The BP would provide the pressure and temperature to ignite and sustain the embedded grains of APCP, like a binder of sorts... and of course using BP as the "binder" would allow the motor to be ignited like regular BP end burning motors, as well as allowing for 'regular' BP type staging... :) The mixture would use the 'souped up' high-ISP APCP to raise the performance while greatly reducing the amount of needed BP to a minimum necessary. I'd bet they could even be designed to be cored...

Probably a serious brain fart on my part, but wonder if it's ever been tried???

OL JR :)

Look up in the various patent databases and you will find a patent 20060272754 belonging to Barry Tunick, Ed Brown, and Scott Dixon, concerning a "pressable" type of potassium perchlorate composite propellant, with about 140% of the power of black powder.

If you want to know how Estes makes motors, in general, this is a good document to read.

[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 mega (http://www.rocketryforum.com/wiki/Mega-)joules (http://www.rocketryforum.com/wiki/Joules) per kilogram (http://www.rocketryforum.com/wiki/Kilogram), and for comparison, the energy density of TNT (http://www.rocketryforum.com/wiki/Trinitrotoluene) 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 mega (http://www.rocketryforum.com/wiki/Mega-)joules (http://www.rocketryforum.com/wiki/Joules) per kilogram (http://www.rocketryforum.com/wiki/Kilogram), and for comparison, the energy density of TNT (http://www.rocketryforum.com/wiki/Trinitrotoluene) 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....

JDDo 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:

http://launchhistory.com/

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

http://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 :D

[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:

http://launchhistory.com/

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

http://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.




JDWell, 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 (http://www.lacunainc.com/) 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 (http://www.lacunainc.com/) 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:

http://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]

DoneOh, 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