Testing the simplest sugar fuel in our simplest rocket motor

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6 ай бұрын

I thought it would be interesting to try a classic Rocket Candy sugar fuel in one of our PVC rocket motors.
Well it didn't go as well as I had hoped. Maybe we could keep increasing the nozzle size but I wasted enough time and money on this project and it's time to move on. As far as I'm concerned, Rocket Candy fuel is an obsolete fuel because there are better alternatives that are just as simple to make.

Пікірлер: 13

@bachirbouihat6590 6 ай бұрын

Keep going 👌

@mojaverockets 5 ай бұрын

I'm not sure how you are casting the R-Candy propellant but from my experience, I've never gotten it to be pourable. And if packing is the method used, it lends itself to lots of voids and will shrink as it cools. Add that to the fact it doesn't bond very well to pvc and you have many ways that it can overpressurize from the increased burning surface. There are ways you can mitigate those issues...use a liner in the pvc case (I've used copy paper), you can add compression on the propellant so that as it cools it bonds tighter to the casing and helps eliminate stress cracking. It is hard to make two or three 'identical' R-Candy propellant motors because of the way it is mixed, stirred, and cast. I've made thousands of 'sugar' motors from 1/4" to 12" diameter monster motors with hundreds of pounds of sugar propellant in each and had hundreds of failures along the way. If you give up you will never know what the problem was and you will be at the mercy that it will happen again. kzfaq.info/get/bejne/m8t_icuCsNS4lps.html Our first two 12" motors worked perfectly, the third test failed. We learned a lot from the failure and look to a fourth successful test in the future.

@rotaryrocketry 5 ай бұрын

So I don't know the final temperature that I got it to, but I did have a pourable R-candy with this project. It was hot... really hot... Much higher than the 230F that I use for Flexi-fuel. Honestly, I gave up on this one because I really think that R-candy using KNO3 & Standard white sugar is an obsolete fuel. As I'm sure you know, there are much more reliable fuels and I was chasing my tail on this. Eventually I just decided it wasn't worth putting in any more time & money. I've used Flexi-fuel in both the cases used in this vid and both motor designs work spectacular with that fuel. I was really just trying to have fun with an old fuel mixture but it proved to be unpredictable & unreliable. It was fun but not worth pursuing. I watched the vid you sent... Really nice. I love how it was buried in the desert for both support and safety. That would have been spectacular if it had exploded.

@WarbirdPylonRacer 6 ай бұрын

I was going to suggest lessening the coring depth to create more of an end-burner and slow the rate down a bit. Nice little project. Thanks for sharing. 👍

@rotaryrocketry 6 ай бұрын

Interesting idea and it would likely reduce internal pressure a bit... But... The way this motor is built, the fuel is cored from the top down so with that method, there is no way to leave an un-cored section at the top.

@WarbirdPylonRacer 6 ай бұрын

@@rotaryrocketry Yeah I suspect that attributes to the rate at which this motor is burning. With this recipe you would need to redesign the motor. Great experiment though. Now we know! ;-)

@mojaverockets 5 ай бұрын

There are many ways to make an end burning sugar motor with an initial core to provide enough thrust for liftoff. Easiest for the method you use is to simply put in a few inches of propellant and allow to solidify with just a 1/4" or so of the coring rod in the surface of the propellant. This will provide a slot for the coring rod in the next section of propellant. There are other ways to but a problem with this it creates a longer burning motor, not good for a pvc case that will get soft and fail with either a burn through or CATO. This method will work with steel case motors or aluminum with an insulating liner. I stopped doing pvc motors long ago because they are single use and just not worth the effort or time.

@rotaryrocketry 5 ай бұрын

@@mojaverockets True... End burning or even multi-grain burning is a significant problem with PVC cases due to heat contact with the casing which typically results in a very quick case failure. Important to keep the burn within the confines of the fuel cell for the entire burn so the fuel is actually protecting the case. This creates it's own set of adventures but that's part of the fun :)