Good HTPB hardeners

[cameronvonbraun]

i was wondering if anyone knew any good hardeners for when you cast an htpb fuel grain

 

[Handeman]

Check the RCS Store. They have good products.

 

[AeroTech]

Check the RCS Store. They have good products.

Thanks. Here is our popular curative in an 8 oz bottle:

https://www.rocketmotorparts.com/Modified_MDI_Isocyanate_Curative/p1577809_7835874.aspx

 

[G_T]

Just to note, since you are asking this question you are not familiar with the chemicals. Suggest you get with someone who is... Note the curatives are pretty toxic including the vapor. It is good to know what you are doing and know the appropriate handling procedures.

HTPB fuel grain - are you making fuel for a hybrid? It would be called propellant if it is fuel+oxidizer -> solid propellant. Discussions that get into the chemistry of these is generally relegated to the research forum. Access is available by request to US citizens, L2 certified (unless the rules have changed; I could be out of date).

I and most any rocketry people with any experience would suggest gaining experience using commercial motors before attempting to make your own. And then, find a mentor to teach you. I do not know you or your background; sorry!

Gerald

 

[cbrarick]

Piece of advice: Get yourself a mentor before you kill yourself.

You live in texas according to your posted information. There's a plethora of Tripoli clubs who can steer you in the right direction and help you find a mentor. Remember, you only have 10 fingers, 2 arms, 2 eyes and 2 lungs. Ruin those and you're done.

 

[sharkbait]

i was wondering if anyone knew any good hardeners for when you cast an htpb fuel grain

Viagra

 

[Antares JS]

Weird question, no additional posts, and not an uppercase letter to be seen. I'm calling roboposter.

 

[cameronvonbraun]

Weird question, no additional posts, and not an uppercase letter to be seen. I'm calling roboposter.

hey i am just new to posting i have never asked one before i am part of a high school rocket team in texas but i just needed to know because we are making a fuel grain

 

[Antares JS]

hey i am just new to posting i have never asked one before i am part of a high school rocket team in texas but i just needed to know bc we are making a fuel grain

Apologies, but your post is very similar to the occasional roboposts we get. That said, punctuation and capitalization are your friends. Using a phone is not an excuse to communicate poorly.

I hope you're at least making a hybrid fuel grain and not an APCP propellant grain. The latter is not something kids should be doing. The former really isn't either, but at least there's little risk of accidentally starting fires until you complete the motor and add oxidizer.

 

[cameronvonbraun]

Apologies, but your post is very similar to the occasional roboposts we get. That said, punctuation and capitalization are your friends. Using a phone is not an excuse to communicate poorly.

I hope you're at least making a hybrid fuel grain and not an APCP propellant grain. The latter is not something kids should be doing. The former really isn't either, but at least there's little risk of accidentally starting fires until you complete the motor and add oxidizer.

Yes sir, we are using a hybrid engine. We are just starting to understand the concept. So we are just needing a little help. Thank you so much.

 

[NTP2]

I hope you're at least making a hybrid fuel grain and not an APCP propellant grain. The latter is not something kids should be doing. The former really isn't either, but at least there's little risk of accidentally starting fires until you complete the motor and add oxidizer.

What about liquids?

 

[manixFan]

Mixing a HTPB grain isn't hard – it's a lot like making a cake. But there are certain precautions that need to be followed, like how to mix the various chemicals in the correct order. And precision and accuracy are critical to getting good, repeatable results. As has been mentioned, finding a mentor in the area who already has experience making HTPB grains is really your best road to success. There are formulas that can be mixed by hand, but most work best if mixed mechanically. In addition to RCS, there are other vendors that supply the chemicals needed, but they are not the kinds of things you want to mix in the house – at minimum you want to be out in the garage, or a workshop with good egress capabilities.

There are many experienced flyers in the Houston area that belong to the local Tripoli club there. I strongly suggest you contact that club and see if they can recommend someone in your area that can help you get started. The fact that you are asking about something as basic as what is a good curative indicates you really need an experienced hand guiding your efforts.

Good luck,


Tony

 

[G_T]

I would suggest instead if you are making a fuel grain for a hybrid that you consider the (chemical exposure) much safer options of 3d printing one of ABS, or casting one using paraffin wax + various additives. Either will give you a good performing fuel grain, provided it and the motor are designed together.

Hybrid fuel when it is burned has a rate at which the surface receeds as it is burned away. This is the regression rate. Same term is used for solid propellant motors BTW.

The regression rate depends on many things, but just for generalities:

HTPB based fuel grains have a low regression rate. So you need a lot of surface area to provide sufficient fuel to go with your oxidizer mass flow rate.

Wax has a high regression rate. So you don't need much exposed fuel surface area to provide enough fuel to go with your oxidizer mass flow rate.

ABS is closer to HTPB in regression rate than it is to wax.

You have to have enough total mass of fuel to cover the expected O:F (oxidizer to fuel) ratio, plus additional to act as chamber insulation. A hybrid typically uses some excess fuel as chamber insulation. Not doing so is a bad plan! Hot oxidizer and combustion chambers mix well, to the detriment of the combustion chamber!

So between required fuel mass, and required surface area, you can start to get some idea of the required geometry of the fuel. But there are additional factors involved and it does get complex. It is, after all, rocket science. What you don't know causes things to go boom.

IMHO, if the things I'm stating above are not already obvious to you, then you are nowhere near ready to work on designing your own hybrid motor. If you are instead working with a commercial hybrid motor and trying to roll your own fuel grain, that is more reasonable. In that case, look at the type of fuel grain already used for that motor, and design one with very similar characteristics - particularly with regard to regression rate.

Wax + sugar, various plastics, various rubbers, asphalt + additives, rolled bonded paper, machined PVC pipe, lots of things can work for the fuel grain. Some better than others of course, and there is no single best answer.

I presume if you are working on a hybrid, you at least have a mentor that is at least L2 certified and hopefully has at least a little experience with hybrids? There is no such thing as a safe rocket motor.

Gerald

 

[cameronvonbraun]

What about liquids?

nah man to expensive

 

[NTP2]

nah man to expensive

Not if you get some kerosene…

 

[cameronvonbraun]

i was told by boss man that we are making a r class rocket motor

 

[NTP2]

i was told by boss man that we are making a r class rocket motor

You need to go in to his office and tell him that he is being an idiot!!!
A R class is supposed to be for space shots not HS!!!!

Ps I’m also in HS so maybe you should listen.

 

[jsdemar]

 

[Rschub]

Everything is bigger in Texas.

 

[Handeman]

i was told by boss man that we are making a r class rocket motor

You need to go in to his office and tell him that he is being an idiot!!!
A R class is supposed to be for space shots not HS!!!!

What @NTP2 said! That requirement is like asking a 14 year old to design and scratch build a safe street legal car. Most adults can't do that.

Is this a ground test only? You should have a bunker and you must have a 2000 ft. safe distance when you fire that thing. If you plan to actually fly it, where? Who's going to do the FAA Class 3 paperwork. The required paperwork is so complicated and in depth, Tripoli has a special committee in place to help members that fly Class 3 rockets do the paperwork.

 

[Brainstormz123]

This could be their team. Brazoswood in Texas has the high school altitude record with a very large hybrid. https://www.systemsgo.org/texas-high-school-rocket-sets-world-record/

 

[Rschub]

 

[TonyL]

Hi "Cameron",
I am calling you "Cameron" because you have not introduced yourself. There is a wealth of information available on this forum, not to mention a much larger mountain of BS. If you would like more of the former and slightly less of the latter, I would suggest that you introduce yourself, what you are doing and why you are doing it

Also most of the people you really want to hear from are 'old', so communicating in a style that does not aggravate them is in your best interest [read: correct punctuation and real words].

What you are describing has a 'how hard can it be?' look on paper, but in practice there are a number of pitfalls that have resulted in possibly no completely successful R size hybrid flights to date by the amateur community [someone else may know of a successful flight(s), I've only seen the several obvious failures, but then I have not really looked either]. People who 'knew what they were doing' have died in hybrid rocket system accidents even using nitrous oxide, so one should take any liquid oxidizer seriously.

Hope this helps,

Tony

 

[brentius]

i was told by boss man that we are making a r class rocket motor

an R? Are you trying to get to space or sth? I'm also in HS, and we've made a D class hybrid. I'm designing a small liquid, but that's a personal project. Solids are banned over here in the UK.

 

[brentius]

i was told by boss man that we are making a r class rocket motor

Start small, make something like an F or G before moving up the ladder. The explosions will be smaller, and so will the cost.

 

[cbrarick]

R class? I'm calling troll.

There was a R class hybrid at BALLS last year, Consensus on the flight line was not a full load of oxidizer due to time constraints.

That's definitely NOT a class project. Especially NOT a high school project

Not enough experience
Not enough engineering knowledge
Not enough manufacturing knowledge
If you're asking about curatives for HTPB, not enough chemistry understanding
Not enough money
No high school rocketeer would be qualified to fly it. AND TARC / SLI wouldn't let you fly it, so where would you do that?

 

[eggplant]

R class? I'm calling troll.

There was a R class hybrid at BALLS last year, Consensus on the flight line was not a full load of oxidizer due to time constraints.

That's definitely NOT a class project. Especially NOT a high school project

Not enough experience
Not enough engineering knowledge
Not enough manufacturing knowledge
If you're asking about curatives for HTPB, not enough chemistry understanding
Not enough money
No high school rocketeer would be qualified to fly it. AND TARC / SLI wouldn't let you fly it, so where would you do that?

Not disagreeing with your individual points, but this poster almost definitely isn't a troll. Here's an example of a previous build done through this program:
https://www.mysanantonio.com/news/e...-class-built-rocket-ready-to-soar-4687656.php

Looks like they launch at White Sands. No idea what their success rate is, but apparently some Texas high schools build big projects.

 

[FredA]

$50k cost to the Gov to shutdown White Sands so they can launch this toy?
WTF
What back door connections do these kids have?

 

[TonyL]

My understanding from my friend that works on base is that WSMR has an educational outreach budget, so schools have a much easier path to fly there.

 

[cameronvonbraun]

thanks tony

Hi "Cameron",
I am calling you "Cameron" because you have not introduced yourself. There is a wealth of information available on this forum, not to mention a much larger mountain of BS. If you would like more of the former and slightly less of the latter, I would suggest that you introduce yourself, what you are doing and why you are doing it

Also most of the people you really want to hear from are 'old', so communicating in a style that does not aggravate them is in your best interest [read: correct punctuation and real words].

What you are describing has a 'how hard can it be?' look on paper, but in practice there are a number of pitfalls that have resulted in possibly no completely successful R size hybrid flights to date by the amateur community [someone else may know of a successful flight(s), I've only seen the several obvious failures, but then I have not really looked either]. People who 'knew what they were doing' have died in hybrid rocket system accidents even using nitrous oxide, so one should take any liquid oxidizer seriously.

Hope this helps,

Tony

Thanks tony,Cameron is fine ,but this is extremely helpful