Blew up a small portion of my yard tonight...

[bitesizebeef]

So I have been experimenting with rocket science, and I successfully made a miniature solid booster a few weeks ago. I decided it was time to up the scale and made a 5 LB booster. At one point during the process of making the booster I got an air bubble in the middle of the solid fuel and it went KABOOM! I have a massive dead spot in my yard now where I had it mounted, but no one got hurt so Im going to be redesigning my mold trying to reduce the amount of air pocket potential. Does anyone have any experience building homemade rockets that could give me a few tips?

[Tea-Assault]

I have experience blowing stuff up with farming fertiliser, but I feel for this type of experiment you may want to ask north korea.. I hear their rockets are in the same stage of development as yours

[zorplex]

First, do NOT experiment with rocket motors. Chemical rockets are basically bombs with holes cut in one side, so if you aren't careful you can very easily make a bomb (which you apparently did) and given the right circumstances it can become deadly. Of course the smaller they are, the less risk there is. But unless you have experience and knowledge going into the design, you can easily make something very dangerous. I'm assuming most of your five pound "booster" is propellant. That's a lot of energy and if you aren't careful things could turn south fast.

Think of this: the largest Estes model rocket motors are 2oz with 1.2oz of propellant. Your 5lb motor likely has something around fourty times the propellant. That really sounds like an accident waiting to happen.

If you insist on making one from scratch, follow some published designs. Do not heavily modify the design. Do not "scale up" the design unless someone else already has and have published those modifications. You'll have to have a nozzel of some sort, and it will only be designed to work with the specified amount of fuel.

If you really want to start making bigger rockets, I suggest instead of using a solid motor, you work toward a hybrid engine. The one I'm most familiar with is a Napthalene-N2O hybrid engine. Of course it won't be as cheap as a solid motor, but it will be much safer. Costs will build quickly but if you want to build anything bigger than a homemade firework, this really is the best way to do it.

Again, please, please, please do not play around with this stuff. It's way too easy to make a simple mistake and if you get too ambitious lives can be lost.

[Hypol33t]

Great job on getting this forum on some kind of security / government surveillance...

[bitesizebeef]

Great job on getting this forum on some kind of security / government surveillance...

Don't worry I'm sure the NSA watch list has been monitoring my activity here long before this

First, do NOT experiment with rocket motors. Chemical rockets are basically bombs with holes cut in one side, so if you aren't careful you can very easily make a bomb (which you apparently did) and given the right circumstances it can become deadly. Of course the smaller they are, the less risk there is. But unless you have experience and knowledge going into the design, you can easily make something very dangerous. I'm assuming most of your five pound "booster" is propellant. That's a lot of energy and if you aren't careful things could turn south fast.

Yep it is a bomb with a controlled burn, I have quite a bit experience blowing things up so I do take safety precautions to reduce risk to humans. Yes I did put a ton of propellant into it.

Think of this: the largest Estes model rocket motors are 2oz with 1.2oz of propellant. Your 5lb motor likely has something around fourty times the propellant. That really sounds like an accident waiting to happen.

If you insist on making one from scratch, follow some published designs. Do not heavily modify the design. Do not "scale up" the design unless someone else already has and have published those modifications. You'll have to have a nozzel of some sort, and it will only be designed to work with the specified amount of fuel.

If you really want to start making bigger rockets, I suggest instead of using a solid motor, you work toward a hybrid engine. The one I'm most familiar with is a Napthalene-N2O hybrid engine. Of course it won't be as cheap as a solid motor, but it will be much safer. Costs will build quickly but if you want to build anything bigger than a homemade firework, this really is the best way to do it.

I have made 5 successful 3oz motors for testing my fuel ratios, I think it was the larger design more at fault than the ratios. I used a cardboard cylinder for the outside with a Styrofoam cylinder inside to to create the passage way for oxygen. I think when i was pouring it into the mold I got an air bubble trapped near the bottom as it hardened. I need to come up with a way of pouring it smoother without risking it hardening before the whole pour is done.

I have thought building hybrid/liquid boosters but, as you said they can be pretty expensive especially when you are trying to get a lot of thrust. I'm pretty certain I will use a liquid engine with oxidizer down the road when I start experimenting with dual stage rockets though. Currently though my goal altitude is so low that solid boosters are much more efficient.

[bitesizebeef]

I have experience blowing stuff up with farming fertiliser, but I feel for this type of experiment you may want to ask north korea.. I hear their rockets are in the same stage of development as yours

funny thing about that Tea, potassium nitrate is what the fertilizer that people makes bombs out of uses, and it is also what a lot of people use as the propellant in home made rocket motors. I however use a different blend and stay as far away from that as I can, because it is much less stable than the mixture I use.

One day I shall overtake the NK rocket program and start a war with them using my fishing boat armed with home made rockets to fight a naval battle.

[Jokerle]

I however use a different blend and stay as far away from that as I can, because it is much less stable than the mixture I use.
.

What do you actually use then? I dont know crap about building a rocket, but someone gave me a chemistry degree.

And as a side note, all university chemistry labs that work with explosive stuff have regular accidents. There are few mutilations, but they do happen.

[Róka]

but someone gave me a chemistry degree.

And as a side note, all university chemistry labs that work with explosive stuff have regular accidents. There are few mutilations, but they do happen.

[bitesizebeef]

I however use a different blend and stay as far away from that as I can, because it is much less stable than the mixture I use.
.

What do you actually use then? I dont know crap about building a rocket, but someone gave me a chemistry degree.

And as a side note, all university chemistry labs that work with explosive stuff have regular accidents. There are few mutilations, but they do happen.

Maybe you could educate me a little bit than. I'm sure you are a much better chemist than I am. I use a mixture of 70% (AP) Ammonium Perchlorate 15% (Al) Aluminum and 15% HTPB.

I guess AP is a lot like Kno3 so I feel like my statement earlier is pretty misleading now that I think about it. It is my understanding that AP is more stable than Kno3 though, maybe you could comment on that Jokerle?

[bitesizebeef]

Well apparently my rocket program is on par with Orbital Sciences after the unfortunate events earlier today. Thankfully it was a unmanned resupply ship so no one was injured. Their explosion was much more impressive than mine though

phpBB [video]

[Róka]

[Wi1D_K4rD]

Well apparently my rocket program is on par with Orbital Science's after the unfortunate events earlier today. Thankfully it was a unmanned resupply ship so no one was injured. Their explosion was much more impressive than mine though

phpBB [video]

FTFY

The rocket itself was built by Orbital Science not NASA.

[bitesizebeef]

The rocket itself was built by Orbital Science not NASA.

Yea, NASA doesn't build any rockets anymore. They outsource all their rocket production to third parties, they do however joint mission control for launch. They don't know what happened to it yet, we will know more in a few days.

I updated the original comment for you

[Jokerle]

Maybe you could educate me a little bit than. I'm sure you are a much better chemist than I am. I use a mixture of 70% (AP) Ammonium Perchlorate 15% (Al) Aluminum and 15% HTPB.

I guess AP is a lot like Kno3 so I feel like my statement earlier is pretty misleading now that I think about it. It is my understanding that AP is more stable than Kno3 though, maybe you could comment on that Jokerle?

AP and KNO3 are both oxidiser, and AP is the stronger one if you compare the redox potentials.
From what I read, AP should actually oxidise water from the differences in redox potentials (thermodynamical argument). However, one finds that AP is actually soluble and thus one assumes it is kinetically quite stable.

Were it not for its kinetic stability AP would be very dangerous to handle. It is surely more "potent" than KNO3.
Just compare the R-phrases from those two (R8 vs R9, R44 ). AP will explode under heat, while KNO3 wont.

I dont know if the resulting mixture with metal is more stable with AP or with KNO3, that depends on how kinetically hindered the reaction with AP is, but AP is probably the more dangerous material by itself.


----
disclaimer:
At least that is my judgement from looking at some data and remembering some basics from my inorganic chem. courses (which are years ago ). I could have overseen something important...

[bitesizebeef]

AP and KNO3 are both oxidiser, and AP is the stronger one if you compare the redox potentials.
From what I read, AP should actually oxidise water from the differences in redox potentials (thermodynamical argument). However, one finds that AP is actually soluble and thus one assumes it is kinetically quite stable.

Were it not for its kinetic stability AP would be very dangerous to handle. It is surely more "potent" than KNO3.
Just compare the R-phrases from those two (R8 vs R9, R44 ). AP will explode under heat, while KNO3 wont.

I dont know if the resulting mixture with metal is more stable with AP or with KNO3, that depends on how kinetically hindered the reaction with AP is, but AP is probably the more dangerous material by itself.


----
disclaimer:
At least that is my judgement from looking at some data and remembering some basics from my inorganic chem. courses (which are years ago ). I could have overseen something important...

And the prophecy read: Bitesizebeef back yard chemist, doesn't know what hes talking about.

That is some very interesting stuff, I was under the impression this whole time that kintetic stability was what made things more safe, from the aspect of preventing things from blowing up, and thermodynamic stability was how big the explosion was. So naturally my logic was, big boom potential that doesn't blow up = safe. Little boom, that blows up frequently = dangerous. Now I must rethink my logic and do more studies.

Damn you and your chemistry degree! Seriously though, thanks for the insight. I am always trying to learn, so I appreciate any chemistry knowledge you can put down. Do you recommend any good books or websites I can learn more about chemistry?

In the non explosion category, my solar cells came in last night, and I made a working prototype solar panel, now I just have to make a more durable/secure housing unit for my panels.