# Alternate Binders

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#### Maxwelljets

##### Well-Known Member
Gotcha. So I just have to build the body and integrate an Estes motor? Then, of course, launch it at some sort of event.
Estes motors are not large enough. Level 1 requires an H or I class motor, level 2 requires a J, K, or L, and level 3 requires an M, N, or O motor. Once you get the cert you're free to buy and fly as many of that cert level of motor that you want. Prior to obtaining the cert you may only buy one at a time, for your cert attempt.

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#### FredA

##### Well-Known Member
You're starting out, so take a clue --
None of these binders have so much higher performance that they're worth pursuing.
There are many other areas to spend you time............

#### Acaicia

##### Active Member
None of these binders have so much higher performance that they're worth pursuing. Many of them were even experimented with by professionals and then abandoned in favor of HTPB. PBAN is one such binder, but it requires elevated cure and is a specialty product. HTPB actually has non-rocketry uses as well, so it's cheaper than many of these options. Another potential binder is PPG (polypropylene glycol), which also has slightly higher theoretical performance than HTPB, but unfortunately it is hygroscopic (absorbs moisture), doesn't wet out solids well (so takes forever to mix), and doesn't age well at all. Others, with worse performance, include polysulfide rubber (some of the earliest composite propellants used this, but it was quickly abandoned) and asphalt (melt-casted).

HTPB is used for a reason.
You somehow solved literally everything in 1 single message. I just so happen to have quite a bit of polypropylene glycol on hand at the moment and I know it's pretty cheap. Didn't really know it was a binder possibility. I use a combination of high pressure and heat treatment to harden my prop thus far, but something like polypropylene glycol or even propylene glycol would work incredibly well for me even though it is less than ideal. Nice and non toxic too.

I do understand PBAN and HTPB are used for a reason, just usually for less budget oriented rockets.

#### Rocket501

##### Well-Known Member
TRF Supporter
I guess. I would say why I need an ungodly amount of propellant for but seeing how this forum is, I'm not sure it would go well. Not gonna lie if I'm going to continue, I will probably need at least my L2 or even L3. Ideally, I can use my current small stage testing to get my L1. Other than the ISP limitations, what does getting my TRA get me?
Large rocket engines are not an issue with us assuming they are discussed in the proper forum for the level of detail. Everything Max says is true, but another major benefit of a TRA L2 is that quite a few people will then be willing to actually sell you the chemicals you need to be successful.

As for the rest, if you are building anything large (20lb+ of prop), epoxy based fuels or the vast majority of hobby binder alternatives just won't suffice. The remaining alternatives all have major issues that make them unappealing or need large amounts of additional research, some of which we are undertaking as a community, but we've still settled on basically just HTPB binders and some like the sugar-derivative ones as well.

As for getting your TRA L2, it is not hard or expensive. The way I recommend to do it is to purchase a binder designs excel 4" single deploy which with the supplies you need to build it, would run you around $110. You will need two engines (one for your L1 and one for your L2) of which I would recommend Aerotech 38mm DMS single use motors (one H-class and one J-class). The blue thunder ones light nicely. These can usually be purchased from an onsite vendor for a total of$120 (before tax). Membership fees are $70 for the first year. In addition to flying the rocket, you'll also have to take a short test, which has all of the answers available for studying, so it is very easy to pass. As such, for a total cost of around$300 (possibly the club might have minor fees as well for launch day), you can get your TRA L2, but I would highly recommend more flights to get some experience first.

While Max mentioned a large number of binders, some other options that just don't work very well for us include plastisol, which I can personally attest is miserable to work with and leads to poor results and modern high-energy military binders which are both obscenely expensive and liquid high explosives, and thus kept very far away from the hands of civilians outside of munitions factories and research labs.

Generally amateurs on an extreme budget stick with sugar derivatives. It's harder than you would expect to get good results with PPG. I expect you may very well end up spending more on trying to get it to work well then it would be to just use HTPB. Finally, what oxidizer are you considering using? Not all binders and oxidizers combinations are compatible.

#### Maxwelljets

##### Well-Known Member
You somehow solved literally everything in 1 single message. I just so happen to have quite a bit of polypropylene glycol on hand at the moment and I know it's pretty cheap. Didn't really know it was a binder possibility. I use a combination of high pressure and heat treatment to harden my prop thus far, but something like polypropylene glycol or even propylene glycol would work incredibly well for me even though it is less than ideal. Nice and non toxic too.
Are you certain it is polypropylene glycol? Propylene glycol (without the poly) will not work. You will also need a diisocyanate curing agent as well to get it to set. Additionally, you will need to know the equivalent weight of your polypropylene glycol if you want to be able to cure it properly.

Second, reread my message and you'll see I went into exactly why PPG is not used. It is hygroscopic, and water A. interferes with the curing process, and B. will partially dissolve the AP. Oxidizers dissolved in fuels are a great way to get rapid unplanned disassemblies. Additionally, PPG does not wet out solids well at all. I have tried using it before. Mixing took hours just to get the solids fully incorporated. HTPB fully incorporates in minutes. In that time, the PPG is sitting out in the open having a bunch of air (and thus humidity) mixed into it. Even if it started out dry, it would not remain dry after mixing. The only way to fix this is to mix under a vacuum, and building a vacuum mixer is way more expensive than just buying a half gallon of HTPB.

Trust me, just use HTPB.

I do understand PBAN and HTPB are used for a reason, just usually for less budget oriented rockets.
Basically every single amateur rocketeer you'll meet who makes APCP will be using HTPB. Every single commercial motor manufacturer uses HTPB. If there were a significantly cheaper alternative that worked as well, do you really think that profit-driven corporations wouldn't be using it?

#### Acaicia

##### Active Member
Are you certain it is polypropylene glycol? Propylene glycol (without the poly) will not work. You will also need a diisocyanate curing agent as well to get it to set. Additionally, you will need to know the equivalent weight of your polypropylene glycol if you want to be able to cure it properly.

Second, reread my message and you'll see I went into exactly why PPG is not used. It is hygroscopic, and water A. interferes with the curing process, and B. will partially dissolve the AP. Oxidizers dissolved in fuels are a great way to get rapid unplanned disassemblies. Additionally, PPG does not wet out solids well at all. I have tried using it before. Mixing took hours just to get the solids fully incorporated. HTPB fully incorporates in minutes. In that time, the PPG is sitting out in the open having a bunch of air (and thus humidity) mixed into it. Even if it started out dry, it would not remain dry after mixing. The only way to fix this is to mix under a vacuum, and building a vacuum mixer is way more expensive than just buying a half gallon of HTPB.

Trust me, just use HTPB.

Basically every single amateur rocketeer you'll meet who makes APCP will be using HTPB. Every single commercial motor manufacturer uses HTPB. If there were a significantly cheaper alternative that worked as well, do you really think that profit-driven corporations wouldn't be using it?
I have both Poly and non poly. The non poly can be made into poly pretty easily if I remember correctly, just a bit of dipropylene should do the trick

#### Maxwelljets

##### Well-Known Member
I have both Poly and non poly. The non poly can be made into poly pretty easily if I remember correctly, just a bit of dipropylene should do the trick
That's not correct. Polymerizing PPG from propylene glycol is a condensation reaction where one water molecule is removed for each propylene glycol. Getting rid of this water from the final product, as well as getting rid of the condensation catalysts, is prohibitively expensive. Commercial PPG is manufactured by ring-opening polymerization of propylene oxide, which is an extremely toxic, very flammable gas that is basically impossible for amateurs to obtain. Making PPG at home is not a viable solution.

Additionally, the PPG used should have a molecular weight of at least 1000 (even higher is better) or else the binder will end up too rigid.

Going down this path will lead you to nothing but frustration and disappointment. The spreadsheet I use to make mix sheets for propellant includes a cost per pound calculator. HTPB is about $120/gal from consumer-facing stores, PPG is around 30 last I checked. When I plug in those numbers for a typical propellant of mine, the price with HTPB ends up around$11/lb, and the price with PPG ends up around $10/lb. IMO that is not at all worth the added headache. Let's put it another way. These are the performance curves of PPG and HTPB at different solids loadings: The US Military, which is willing to use highly sensitive explosive binders like GAP and explosive additives like RDX in order to get better performance, gave up on PPG in favor of HTPB. There's roughly a 5s Isp difference between the two. Unless PPG had some terrible downsides, they'd be using PPG for everything. The fact they're using HTPB instead should tell you everything you need to know. Last edited: #### Acaicia ##### Active Member That's not correct. Polymerizing PPG from propylene glycol is a condensation reaction where one water molecule is removed for each propylene glycol. Getting rid of this water from the final product, as well as getting rid of the condensation catalysts, is prohibitively expensive. Commercial PPG is manufactured by ring-ope ing polymerization of propylene oxide, which is an extremely toxic, very flammable gas that is basically impossible for amateurs to obtain. Making PPG at home is not a viable solution. Additionally, the PPG used should have a molecular weight of at least 1000 (even higher is better) or else the binder will end up too rigid. Going down this path will lead you to nothing but frustration and disappointment. The spreadsheet I use to make mix sheets for propellant includes a cost per pound calculator. HTPB is about$120/gal from consumer-facing stores, PPG is around 30 last I checked. When I plug in those numbers for a typical propellant of mine, the price with HTPB ends up around $11/lb, and the price with PPG ends up around$10/lb. IMO that is not at all worth the added headache.
I'll experiment around a bit.

#### Rob702Martinez

##### Zip-Tie Oversight Committee
TRF Supporter
I guess. I would say why I need an ungodly amount of propellant for but seeing how this forum is, I'm not sure it would go well. Not gonna lie if I'm going to continue, I will probably need at least my L2 or even L3. Ideally, I can use my current small stage testing to get my L1. Other than the ISP limitations, what does getting my TRA get me?
So why do you need an ungodly amount of propellant?

#### Banzai88

##### Lvl 1,Wallet....Destroyed
TRF Supporter
So why do you need an ungodly amount of propellant?
Probably the single most important question so far.

#### FredA

##### Well-Known Member
If the OP only thinks he might need his L3, then his "ungodly amount" is actually pretty small.
For an L2 -- one of my 25# batches would be an ungodly amount -- lots of little motors.....
I think this usage of ungodly can be chalked up to "everything is relative."

#### AeroTech

Estes does not sell high-power motors. L1 certification requires use of an H or I-class high-power motor. L2 certification requires a J, K or L-class motor. L3 certification requires an M or higher class motor.

Epoxy curatives also generate lots of ammonia when used with AP.

Gotcha. So I just have to build the body and integrate an Estes motor? Then, of course, launch it at some sort of event.

#### prfesser

Damn now I remember why I don't like hobby specific forums. There's always one of these ^^
My apologies. I should not have posted as I did. Just that we have all seen SO many people --- usually enthusiastic young men --- who join TRF and immediately ask how to make rocket "fuel" (a misnomer). It becomes tiresome after a while. (For an idea of "a while", the first times I've encountered such requests were often from those styling themselves as "kewl bomz d00ds" or something similar.)

For what it's worth, the ingredients for high-quality solid rocket propellant will run on the order of $50-60/kg today, plus shipping and hazmat (some ingredients must be picked up at the source or shipped by truck --$100 or thereabouts to start). For making more than very small (100 g) batches, minimum equipment and ancillary materials will run at least $300-400, not including safety equipment. And a good place to work; garages are rarely satisfactory, and young men who start house fires are rarely looked upon with favor by parents/spouses/emergency responders... One piece of advice: there are good sources and bad sources of information on YouTube and the like. Popularity is not a good indication of quality, merely a good indication of...well...popularity. Unfortunately there is no good way to determine whether a source of information is actually useful knowledge. ("I did this and it werks!" is a data point, not really information much less knowledge.) Regards -- TWM #### boatgeek ##### Well-Known Member So why do you need an ungodly amount of propellant? Probably the single most important question so far. I don't normally wade into threads like these, but the "why" here is fascinating to me. The OP is strongly implying that this amount of propellant is needed for a secret SpaceX project, possibly for the military. If that were the case, doesn't SpaceX have a number of people on staff who could address the propellant mix issues? Sure, they're mostly liquids people, but they must have a few people on staff who have made composite propellant either in class, as a hobby, or professionally. If not, they could definitely hire a consultant (maybe even our professor!) for a couple thousand bucks. Would the X have trouble sourcing materials or be worried about a few dollars per pound? If it's a job requiring dozens to hundreds of pounds of propellant, the customer is expecting to pay big bucks and the cost argument goes away completely. This all just doesn't make sense. If it's not a SpaceX project, then why act like it is? I don't particularly need an answer, it just struck me funny. Carry on. #### RocketRev ##### Lifetime Supporter TRF Lifetime Supporter Dear Acaicia, While I think that every person on this thread, myself included, is thankful for your service to our country, your other "credentials" don't really mean much. The very fact that you are disrespecting the decades long experience of the exact people from whose expertise you are asking for them to share, says more about you than you apparently are aware. If you are going to get angry because the Prfesser calls you a "newby," then you don't understand what a "newby" is. Terry is NOT saying you're an idiot or stupid or anything derogative at all. It just means that you are new to this hobby and like so many others before you, you apparently think that you are ready for something that by your own line of questioning and your response to the answers that have been shared, you clearly indicate that you are not. You are asking very basic questions about binders and are getting very good information from people who actually know about binders from actual experience working with various binders and you are responding that you know better. If you know so much and have so much experience, and your credentials clearly give you all the information that you need to disagree with the information that you are receiving, then why are you asking for help? Please reread this whole thread. The responses that you've gotten actually answer every single one of the objections that you've raised. Unfortunately, you seem to be dismissing the responses that you've gotten because you know better. To echo what you haven't allowed yourself to hear, you are a newby. So please start listening to the incredibly good information that is being shared with you. The only engineering credentials that I have are from working as an aeseptisary-hygienic site services engineer. But you'll also note that I've not shared any of my expertise on the various binders mentioned on this thread. That's because I own and have thoroughly read thru and used the Prfesser's book (an EXCELLENT resource that you ought to purchase A.S.A.P., if you are seriously thinking of making your own propellant) and have successfully made my own propellant which I gladly flew in my own rockets. But, I am wise enough to know that I'm not a propellant engineer like the people who have been answering your questions. The research thread is where they can get into all the technicalities of the answers to the questions that you've been asking. This thread is in the open forum section and as has been stated over and over again. The very technical questions that you are asking can only be fully answered in the research section of this forum. But by your own admission you are not yet credentialed enough to get into that section of this forum. And the credentials that you need are very practical in the real world experience. I can read between the lines like everybody else. You clearly have some major goal in mind for which you are aiming. Nobody here is disrespecting you for having lofty goals. Lofty goals is par for the course in this hobby (small joke). But please do not make the mistake of assuming that because this is a hobby, the folks that have been sharing information from their areas of expertise with you are not professionals. Its quite the opposite in fact. The Prfesser is an actual college professor in chemistry and has so much in the way of credentials for talking about rocket propellant as to be almost over qualified. So instead of dismissing the information being shared with you from the very experts that you have been asking to share their expertise, please listen. And in the mean time get some actual high power rocketry experience under your belt. You're going to need it. And the loftier your goals, the loftier your "in the real world" experience is going to need to be. By the sounds of it, you're going to need your L-3 which means that you will need to deal with people who likewise have "in the real world" experience. Your lack of ITRL experience is not very reassuring at this point. Brad, the "Rocket Rev.," Wilson TAP and L3CC (and if you don't know what those mean, then you really need to do some more research) #### Acaicia ##### Active Member If the OP only thinks he might need his L3, then his "ungodly amount" is actually pretty small. For an L2 -- one of my 25# batches would be an ungodly amount -- lots of little motors..... I think this usage of ungodly can be chalked up to "everything is relative." 700 KG #### Acaicia ##### Active Member My apologies. I should not have posted as I did. Just that we have all seen SO many people --- usually enthusiastic young men --- who join TRF and immediately ask how to make rocket "fuel" (a misnomer). It becomes tiresome after a while. (For an idea of "a while", the first times I've encountered such requests were often from those styling themselves as "kewl bomz d00ds" or something similar.) For what it's worth, the ingredients for high-quality solid rocket propellant will run on the order of$50-60/kg today, plus shipping and hazmat (some ingredients must be picked up at the source or shipped by truck -- $100 or thereabouts to start). For making more than very small (100 g) batches, minimum equipment and ancillary materials will run at least$300-400, not including safety equipment. And a good place to work; garages are rarely satisfactory, and young men who start house fires are rarely looked upon with favor by parents/spouses/emergency responders...

One piece of advice: there are good sources and bad sources of information on YouTube and the like. Popularity is not a good indication of quality, merely a good indication of...well...popularity. Unfortunately there is no good way to determine whether a source of information is actually useful knowledge. ("I did this and it werks!" is a data point, not really information much less knowledge.)

Regards -- TWM
To be fair I do 100% qualify as an enthusiastic young man. More or less came here looking for alternate binders as I have a pretty good idea as to what my fuel+oxi is. I completely understand it probably gets tiring of people coming here and just straight up asking how to make rocket fuel. My budget is larger but still limited, hence me trying to find a slightly more cost effective binder. I certainly don't plan on using a bottom shelf alternative for an airborne application if that's your concern. More or less it's an experiment done in a proper facility complete with remote ignition sources and vent systems in the scenario of a bad reaction. I might come off as relatively inexperienced (which I evidently am in many fields), but nieve doesn't quite fit.

Cheers!

#### Acaicia

##### Active Member
Dear Acaicia,

While I think that every person on this thread, myself included, is thankful for your service to our country, your other "credentials" don't really mean much. The very fact that you are disrespecting the decades long experience of the exact people from whose expertise you are asking for them to share, says more about you than you apparently are aware.

If you are going to get angry because the Prfesser calls you a "newby," then you don't understand what a "newby" is. Terry is NOT saying you're an idiot or stupid or anything derogative at all. It just means that you are new to this hobby and like so many others before you, you apparently think that you are ready for something that by your own line of questioning and your response to the answers that have been shared, you clearly indicate that you are not.

You are asking very basic questions about binders and are getting very good information from people who actually know about binders from actual experience working with various binders and you are responding that you know better. If you know so much and have so much experience, and your credentials clearly give you all the information that you need to disagree with the information that you are receiving, then why are you asking for help?

Please reread this whole thread. The responses that you've gotten actually answer every single one of the objections that you've raised. Unfortunately, you seem to be dismissing the responses that you've gotten because you know better. To echo what you haven't allowed yourself to hear, you are a newby. So please start listening to the incredibly good information that is being shared with you.

I can read between the lines like everybody else. You clearly have some major goal in mind for which you are aiming. Nobody here is disrespecting you for having lofty goals. Lofty goals is par for the course in this hobby (small joke). But please do not make the mistake of assuming that because this is a hobby, the folks that have been sharing information from their areas of expertise with you are not professionals. Its quite the opposite in fact. The Prfesser is an actual college professor in chemistry and has so much in the way of credentials for talking about rocket propellant as to be almost over qualified.

So instead of dismissing the information being shared with you from the very experts that you have been asking to share their expertise, please listen. And in the mean time get some actual high power rocketry experience under your belt. You're going to need it. And the loftier your goals, the loftier your "in the real world" experience is going to need to be. By the sounds of it, you're going to need your L-3 which means that you will need to deal with people who likewise have "in the real world" experience. Your lack of ITRL experience is not very reassuring at this point.

TAP and L3CC (and if you don't know what those mean, then you really need to do some more research)
I'm asking here because quite frankly I don't know everything. I'm not short on knowledge, just experience. I can guarantee almost anyone on this forum has made more SRF and more complex SRF formulas than me. My credentials don't mean I know everything, if anything it should tell you what I DON'T know. I specialize in orbital trajectory calculations, thus I know at least a little in fuels, but that certainly doesn't make me an expert.

I do understand this a hobby forum, but believe it or not I came here expecting experts. I don't know any beginning hobbyists who could populate a large forum like this.

#### boatgeek

##### Well-Known Member
700 kg is roughly puts you roughly in the full T or baby U motor range*. If you're building something that large, the price of fuel components is almost irrelevant. There are so many things that are far more expensive than the fuel at that point. If you have that much money to spend, spend a few grand on a consultant on the fuel mix. It will probably save you money in the long run anyway as you avoid expensive dead ends.

* An O8000 at 41K N-s has 18.6 kg of propellant. 700 kg would put you around 1.5M N-s assuming N-s scales reasonably linearly with propellant mass. And I never thought I'd say the words "baby U."

#### Acaicia

##### Active Member
700 kg is roughly puts you roughly in the full T or baby U motor range*. If you're building something that large, the price of fuel components is almost irrelevant. There are so many things that are far more expensive than the fuel at that point. If you have that much money to spend, spend a few grand on a consultant on the fuel mix. It will probably save you money in the long run anyway as you avoid expensive dead ends.

* An O8000 at 41K N-s has 18.6 kg of propellant. 700 kg would put you around 1.5M N-s assuming N-s scales reasonably linearly with propellant mass. And I never thought I'd say the words "baby U."
700 KG ~ more specifically. In theory, it could scale up to 900 KG. If anything, at that size the price becomes MORE relevant. A mere dollar per KG means 900 extra dollars. Pennies will be pinched aggressively during this project.

#### Rocket501

TRF Supporter
Will 700KG be used in a single motor? Have you considered the difficulties in processing that amount of propellant? I think it is quite likely that by trying to save less than a dollar per kilogram using PPG as your binder you could end up adding $10,000+ in equipment needed for motor processing, not even including the increased risk of motor failure and research you would need to conduct. It doesn't seem like a good tradeoff to me. Also, if I guess correctly, you are planning on using ammonium nitrate as an oxidizer, which needs special tricks if you want to get it to work at all, especially at that size. There's many reasons why we don't really use it all that much as amateurs and why professionals avoid it. Finally, you should really have to ask yourself if you truly need a motor of that size, or if there might be some method of using a smaller rocket booster to accomplish the same task through improved design or an alternative approach. #### Acaicia ##### Active Member Will 700KG be used in a single motor? Have you considered the difficulties in processing that amount of propellant? I think it is quite likely that by trying to save less than a dollar per kilogram using PPG as your binder you could end up adding$10,000+ in equipment need for motor processing, not even including the increased risk of motor failure and research you would need to conduct. It doesn't seem like a good tradeoff to me. Also, if I guess correctly, you are planning on using ammonium nitrate as an oxidizer, which needs special tricks if you want to get it to work at all, especially at that size. There's many reasons why we don't really use it all that much as amateurs and why professionals avoid it. Finally, you should really have to ask yourself if you truly need a motor of that size, or if there might be some method of using a smaller rocket booster to accomplish the same task through improved design or an alternative approach.
I'm not even close to getting a fully operational 700-900KG motor at the moment. Starting small until I've learned all the tiny quirks of my fuel.
Chances are, I'll be using Ammonium perchlorate. A tried and true oxi, and if that doesn't work I can use Potassium perchlorate or Sodium perchlorate. I would tell you what all the components of the motor will be but seeing how binders are a protected subject, I have no doubt a full formula will get me flamed.

Indeed, I'm afraid a motor of that size will be necessary in the long run. Once again, if I say what I need such a large motor for, chances are I'll be permanently disqualified from my L3

#### Maxwelljets

##### Well-Known Member
When buying HTPB in bulk, as you will need to in order to mix that much propellant, the cost drops significantly. 55 gallons of HTPB can be had for around $50-$70/gal. You could then make back part of the cost of this by selling any excess HTPB. Many people here would love to take some off your hands.

Sodium perchlorate is a bad plan because it's hygroscopic, and potassium perchlorate is a bad plan because it results in very high pressure exponents (burn rate is very sensitive to pressure). Ammonium perchlorate also has higher performance than the other options you listed there.

#### boatgeek

##### Well-Known Member
700 KG ~ more specifically. In theory, it could scale up to 900 KG. If anything, at that size the price becomes MORE relevant. A mere dollar per KG means 900 extra dollars. Pennies will be pinched aggressively during this project.
That puts you at roughly 4 times the propellant mass of the CSXT/Go Fast rocket. I don't remember the exact cost of that project, but I'm pretty sure it was on the order of $1-2 million. You'd then be looking at a ~$2-5 million project. $900 extra for the propellant is insignificant in the grander scheme. That scale of project is not a place to try to pinch pennies.  For sense of scale of what you're getting into, the mixer to mix up an O or so test motor will cost you a couple of grand at least. [/edit] Indeed, I'm afraid a motor of that size will be necessary in the long run. Once again, if I say what I need such a large motor for, chances are I'll be permanently disqualified from my L3 If that's the case, then it's a spectacularly bad idea. You're not doing it for work or it wouldn't disqualify you from L3. If it's that far out of bounds, it's likely illegal and could at minimum cost your job at SpaceX. Employers requiring security clearances really frown on employees who break the law deliberately. #### Rocket501 ##### Well-Known Member TRF Supporter I'm not even close to getting a fully operational 700-900KG motor at the moment. Starting small until I've learned all the tiny quirks of my fuel. Chances are, I'll be using Ammonium perchlorate. A tried and true oxi, and if that doesn't work I can use Potassium perchlorate or Sodium perchlorate. I would tell you what all the components of the motor will be but seeing how binders are a protected subject, I have no doubt a full formula will get me flamed. Indeed, I'm afraid a motor of that size will be necessary in the long run. Once again, if I say what I need such a large motor for, chances are I'll be permanently disqualified from my L3 Ammonium perchlorate is going to run you a bare minimum of$6/lb if you are lucky enough to purchase old stock, more like twice that if you have to buy new stock. It's still the best option we have. Potassium perchlorate and sodium perchlorate both have major issues. What max says is true, you will not save money trying to use something other than HTPB. You'd be able to purchase it in bulk, which is a great deal.

As for being disqualified from an L3, I don't think that can actually happen, unless you are talking about something that could get you arrested, and I'm pretty sure even ex-felons can get certified. However, if it is illegal, I wish to give no further advice.

#### Banzai88

##### Lvl 1,Wallet....Destroyed
TRF Supporter
Pennies will be pinched aggressively during this project.
DANGER WILL ROBINSON.

DANGER

None of this is adding up to a good idea.

#### Acaicia

##### Active Member
When buying HTPB in bulk, as you will need to in order to mix that much propellant, the cost drops significantly. 55 gallons of HTPB can be had for around $50-$70/gal. You could then make back part of the cost of this by selling any excess HTPB. Many people here would love to take some off your hands.
I've done a bit of research and some asking around, in theory, I could source bulk for $45~ per gallon bulk, or about$14 per KG

#### Acaicia

That puts you at roughly 4 times the propellant mass of the CSXT/Go Fast rocket. I don't remember the exact cost of that project, but I'm pretty sure it was on the order of $1-2 million. You'd then be looking at a ~$2-5 million project. $900 extra for the propellant is insignificant in the grander scheme. That scale of project is not a place to try to pinch pennies.  For sense of scale of what you're getting into, the mixer to mix up an O or so test motor will cost you a couple of grand at least. [/edit] If that's the case, then it's a spectacularly bad idea. You're not doing it for work or it wouldn't disqualify you from L3. If it's that far out of bounds, it's likely illegal and could at minimum cost your job at SpaceX. Employers requiring security clearances really frown on employees who break the law deliberately. I'm avoiding doing large scale testing until I have proper permission to make 700 KG of explosives. Starting small at the moment, tops .5KG for small scale testing, thrust curves, potential TWR calculations, etc. The last thing I want is my beloved TS to go away. #### Rocket501 ##### Well-Known Member TRF Supporter I've done a bit of research and some asking around, in theory, I could source bulk for$45~ per gallon bulk, or about \$14 per KG
Then you have no reason to do anything else. Also, APCP is legally not an explosive, but you may need a license for extremely large quantities of AP.

Finally, without a vague hint of what your intended application is, I think most of us would be hesitant to give further advice.

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