As a child I enjoyed my basement laboratory (I wrote about it in one of my earlier stories) and have many fond and thrilling memories of the experiments I tried there. Recently I was reading an online article from a 1935 edition of Popular Mechanix and realized that the culture I grew up in was surprisingly open to letting children experiment with chemicals, rockets, and nuclear energy. Today, it seems, our culture is much more wary of the idea of playing with radioactive materials, powerful acids, or explosives (the way a child would think of playing). But as a child, I certainly played with some dangerous things. And while my parents were very supportive of my amateur science tinkering, they did not really know what I was doing nor did they understand how dangerous my playing was.
I cannot remember exactly how I determined the components I needed to make my own rocket fuel. I had always been interested in flying, space flight, and rockets. So it seemed a natural extension of those interests that, around the age of 15, I would wonder how to make rocket fuel and attempt it on my own. Somehow I came to the idea that Kraft caramels (as a source of sugar) and some potassium nitrate (saltpeter) would make an appropriate fuel. My 'recipe' required mixing these two ingredients and then igniting them.
Growing up on a farm, I had easy access to propane torches, but I usually had to improvise methods to heat, mix, or store materials. So after getting the caramels and the potassium nitrate, I decided that a good way to melt them would be in some small, metal container. In those days, 35mm photographic film came in small aluminum canisters (they are plastic now). The melting point of aluminum was fairly high (close to 1500 degrees, I thought), so I supposed I was safe to use it as a container to melt the mixture. After melting it, I was going to let it cool and solidify. This would produce a hard cylindrical rod of rocket fuel. I would then find a way to mount it in a rocket and ignite it.
I knew my mother made popcorn balls with melted Kraft caramels, and she always used what she called a "double boiler"; essentially it melted the caramels by using the heat from boiling water...so that the caramels melted slowly at less than the boiling point of water. But I did not have anything like a double boiler in my little laboratory, and besides, I wanted a quicker way to melt the caramels. So I decided I could just put the two ingredients together in the aluminum canister and apply heat from the propane torch and everything would be fine.
I was home alone on the day that I set out to make my rocket fuel. And things started out well...
I placed the canister containing the mixture in the middle of my laboratory work bench. The bench-top was made of 3/4 inch plywood (again, I didn't have any special equipment to hold the canister). Holding the propane torch, I carefully heated the canister. I could tell it was going to take awhile to melt the caramels so I moved the torch closer to increase the heat and suddenly the ingredients started to flash and pop. Quickly I pulled the torch away and whatever reaction had started immediately stopped. I applied the flame from the torch again to the canister and after a moment the popping and flashing started again. I was not sure what was happening or why...but I decided it was not a good thing; the rocket fuel was close to igniting before the mixure had even melted (and igniting it was not what I was trying to do yet). So I continued to carefully heat the mixture and would pull the torch away if anything started to pop or flash.
But while I was trying to be careful, this was still taking a long time. So each time it started popping, I held the heat on a little longer. After several close calls, I finally did not remove the heat quickly enough. Suddenly, the mixture ignited.
My memory of the next few seconds is rather chaotic. I saw a huge flame leap up from the mouth of the canister, half-way to the ceiling of the basement. I jumped under a nearby table (I can't remember what happened to the propane torch). Crouched under the table, I heard a roaring noise and watched a pillar of fire and thick smoke spew from the top of my work bench. It could not have lasted more than a few seconds, but in those seconds I thought I had burned the house down. I was not sure what was going to happen in the basement where I was (would it explode? how long would it burn...?). I was frozen with fear.
Then I realized the noise and the flame had ended. The basement was full of smoke which was slowly drifting upstairs. I got out from under the table and looked at my work bench. There was a 4-inch circle of charred wood and a tiny crater eaten down into the plywood. There in the bottom of that crater was a solidified pool of aluminum. It was no longer a canister but just a blob of metal. I was shaking, glad to be alive, and then realized the house was not going to burn down. But it would smell very strange for a while. I can't remember how I aired the house out; I don't think anyone (my parents or siblings) ever knew what had happened.
So while I did make rocket fuel, I did not have anything to show for it. Except I decided I wouldn't try it again. I felt fortunate to have escaped the incident – with new knowledge and a new respect for some fairly simple chemicals.
I've told this story a few times to family and friends, they usually think it is funny and they laugh. I chuckle too (but I can do that now).
I've always thought of this story as an example of being a dry farmer... curiosity mixed with inadequate information and not a lot of caution. Maybe experiences like this happen to everyone. Or maybe growing up on a farm just let me try different things than other kids (or my own kids). I don't know.
