Sugar Rocket Motors Are Underpowered

[KG7UAT]

Hey there,

I've been working on making homemade sugar rocket motors. What originally got me started on this path was a YouTube video from the King of Random on how to make your own sugar motors. I'd been into rockets before but stopped doing it due to the cost of the motors. Making the motors looked simple, easy, and cheap, and that lured me back into the hobby. Besides that video, I've done some reading on making sugar motors and to make sure I'm working within the laws of the federal, state, and county governments.

There are multiple ways to make a motor. Some cook the mixture, others just hammer it in the tubes dry. Since I don't have a very good way of cooking it, I decided to just do it dry. I know I'd probably get better results if I did cook it, but the King of Random did his dry and it worked and I've heard of others doing it dry and that worked fine, so I figure mine would work just as well.

Rummaging through my room, I found quite a few empty Estes B6 motors and quite a few more empty A10-3T motors. I decide to use the old motor casings to put my sugar mixture into, that way I didn't have to buy new tubes (these were just as good) and they'd fit into my rocket easy-peasy.

To make the sugar fuel (which I call "white mix") I finely ground and then mixed a 65:35 ratio of KNO3 and Organic Cane Sugar (no added ingredients). After thoroughly mixing it, I pour the white mix into the motor casing and press it down with a dowel and then gently tap it with a mallet. Next comes the delay mix which is the exact same thing as the white mix but contains 15% baking soda by weight. I put a little bit of that on the top before capping it off with powdered kitty litter. To do the parachute ejection charge, I hand drill a small hole in the kitty litter end cap and then add a bit more white mix. The motor is then done.

So that's how I make my KNO3-sugar powered rocket motors. But I wouldn't be on here now if that worked just fine. It doesn't. My rocket motors do not produce enough thrust to lift the rocket. The rocket just sits on the pad as the motor burns away and I'm not sure why. When I slide the rocket down the launch pad pole, it slides just fine, so the issue is not there. I thought the problem could be with my KNO3. I know potassium nitrate is hygroscopic, so I wondered if the KNO3 just had too much water in it and thus it didn't burn well. But even after drying out the KNO3 in the oven for 30 minutes at 300 degrees Fahrenheit and creating a new batch of white mix, my motors still don't provide enough thrust. Up to this point, I had been using Estes B6 size empty motor casings, but after several episodes of unsuccess, I decided to try an A10-3T motor. Rockets that use these smaller engines are smaller and lighter themselves, so I hoped that the lighter weight would make the difference, despite the fact that the smaller engines would also contain less fuel. But that didn't work either, I got the exact same results. Now I really wondered if the motor was powerful enough to lift even itself, so I tried that, and it could, but it will not lift a rocket.

I'm not sure what to do.

[patsroom]

I had the same thing happen to me. I read somewhere to add a pinch of red oxide (rust) to the mix, I did and the rockets flew after that. To test find some rust and sanded it off of the rusting object and add it to the powder. That should improve your motors. If it does you can order some of that off-line....................Pat

[stix]

+1 what pat said regarding RIO. You can pick it up at a hardware store - it's often used for colouring cement and cheap as. You could also drill into the core from the nozzle end maybe around half an inch. You you try both methods together.

 

I did something similar a while back with an empty Estes C6 motor. I used melted KNSU+1%RIO and drilled into the core around half an inch. I attached it to a stick, lit the fuse, and it took off like the powers of piss, so much so that I found myself giggling

Edited November 19, 2018 by stix

[KG7UAT]

Hey thanks for the idea! That actually makes a lot of sense. When I did some reading on sugar motors, a few sites mentioned using iron oxide, but I never thought much of it since only a few mentioned it. I'll definitely have to give that a try. I don't having any rust or anything rusting, so a friend is going to bring me some. I'll let ya'll know what happens!

 

Thanks again!

[stix]

Sounds good.

 

Just be careful in case you have more thrust than you thought. An Estes D12 clay nozzle flung into your eyeball is not a good outcome.

 

Be Safe.

 

cheers.

[MadMat]

In your reading, did you learn the difference between end-burners and core-burners? I say this because, according to your description, you are making end burners. I have had very little success with end burner sugar rockets, especially without RIO. Even with RIO added, end burner Rcandy rockets can be somewhat anemic. IMHO, I would put a core into your engines, but as Stix said, be careful, this will definitely increase the output. One thing to consider.... reusing Estes tubes may seem very convenient, but the ratio of nozzle diameter to ID of tube is optimized for black powder. Although this difference is probably rather small, it could be adding a difficulty someone new to this doesn't need

Edited November 21, 2018 by MadMat

[nils]

Dry hammering or melting method are not good enough for end burner. Smaller nozzle hole helps to increase the internal pressure and bigger pressure makes sugar fuel burn faster.

To get the best and fastest burning mixture it is neccessary to completely dissolve KNO3 and sugar in water and then boil the water out.

I add red iron oxide in the end of boiling out. This way I can avoid overheating visually. Mixture must not become too brown.

[MadMat]

A few other thoughts on your manufacturing process. By pressing (or hammering) a dry mixture, you are putting a lot of impact on the nozzle/plug of the reused engine. If you don't have a close fitting mandrel to support the plug, it can cause it to crack and fail. Additionally, the nozzles will erode after a firing and get larger in diameter. If, as I suspect, the nozzle of an Estes motor is a bit large for Rcandy in the first place, any erosion will just put it farther out of wack. As Nils stated; "Smaller nozzle helps to increase internal pressure...." if the nozzle is too big you will get a FTL (failure to launch) But remember, if the nozzle is too small, the tube can fail. Tube failures do include explosions.

Edited November 25, 2018 by MadMat

[dagabu]

*At the Federal level, sugar rocket fuel is not within the specific outline of low explosives but should be considered 'Black Powder' for the sake of remaining unaccosted by federal officials. It IS mentioned in the NFPA 1122 and almost all states have adopted the 1122 in their fire code, this means that at the state level, all the rules in the NFPA 1122 must be followed as well as local laws and ordinances. LINK (OLD) Also, this is a good read but be aware that this was written BEFORE the 2009 ruling on APCP motors. https://www.atf.gov/file/56316/download

 

The fact that NAR rocketry is recognized and its safety and launch site requirements are codified in Codes 1122 (Model Rockets) and 1127 (High Power Rockets) by the National Fire Protection Association, will be a very powerful part of your discussion with any fire marshal.

NFPA 1122

Code for

Model Rocketry

2002 Edition

3.3.6* Model Rocket. A rocket that (1) weighs no more than 1500 g (53 oz)with motors

installed; and (2) is propelled by one or more model rocket motors having an installed total

impulse of no more than 320 N­sec (71.9 lb­sec); and (3) contains no more than a total of

125 g (4.4 oz) of propellant weight.

3.3.8* Model Rocket Motor. A rocket motor that has a total impulse of no greater than 160

N­sec (36 lb­sec), an average thrust of no greater than 80 N (18 lbf), and a propellant weight

of no greater than 62.5 g (2.2 oz), and that otherwise meets the other requirements set forth

in NFPA 1125, Code for the Manufacture of Model Rocket and High Power Rocket

Motors.

4.2.3 A model rocket motor shall be assembled with all pyrotechnic ingredients preloaded

into a cylindrical paper or similarly constructed nonmetallic tube that does not fragment into

sharp, hard pieces.

The exemption below only relates to the Federal Government, your state may have rigorous rules such as my home state: The laws in Minnesota prohibit any manufacturing of any pyrotechnic device without a license:

 

Class 1 – Model Rocket

Which is an amateur rocket that:

Uses no more than 125 grams (4.4 ounces) of propellant;

Uses a slow-burning propellant;

Is made of paper, wood, or breakable plastic;

Contains no substantial metal parts; and

Weighs no more than 1,500 grams (53 ounces), including the propellant.

The Orange Book (BATFE) Federal Explosives Law and Regulations, Subpart H—§ 555.141 Exemptions

(10) Model rocket motors that meet all of the following criteria—

(i) Consist of ammonium perchlorate composite propellant, black powder, or other similar low explosives;

(ii) Contain no more than 62.5 grams of total propellant weight; and

(iii) Are designed as single-use motors or as reload kits capable of reloading no more than 62.5 grams of propellant into a reusable motor casing.

*all the above was taken from the internet, I am not offering advice nor do I know or understand the laws or codes in your area nor should you proceed with making devices that may/will harm you.

 

Hey there,

I've been working on making homemade sugar rocket motors. What originally got me started on this path was a YouTube video from the King of Random on how to make your own sugar motors. I'd been into rockets before but stopped doing it due to the cost of the motors. Making the motors looked simple, easy, and cheap, and that lured me back into the hobby. Besides that video, I've done some reading on making sugar motors and to make sure I'm working within the laws of the federal, state, and county governments.....

.....I'm not sure what to do.

 

[KG7UAT]

Hi there!

 

Didn't realize there was ongoing discussion. Thanks for your tips and suggestions everybody!

 

Yes, I do remember in my research reading a little about core and end burning motors, I didn't think too much about it. I guess I should give core-burners a try.

 

I'm using an Estes B6-4 size motor, which looks to have a hole size of .5cm (half a cm). Is that too big or too small? I've been very careful when hammering my mix in because I've damaged a few motors by hammering too hard. The nozzle seems to stay in tact quite well, but my main issue is that the tube can bend or break if you are not gentle with it. I haven't noticed any nozzle erosion, but I'll definitely keep an eye out for that.

 

Thanks nils for your suggestion, but I don't have a good way to cook the KNO3/sugar mixture, so I'm just doing dry at this time. From what I've heard, cooking it is definitely better, but I'm fine with dry packing it as long as it produces some good results.

 

Update on how my rocket motors are coming along: A friend of mine has promised to give me some rust, but he lives an hour away and I haven't seen him lately. Going to pick it up this weekend and then give it a try. Thanks your suggestion!

[KG7UAT]

I'm using an Estes B6-4 size motor, which looks to have a hole size of .5cm (half a cm). Is that too big or too small?

 

Looks like I answered my own question:

 

I was blown away from the power of this motor (not to be taken literally). Thanks MadMat for the core burner idea! That seems to have done it! I'll just need a bigger hole in my nozzle. I'm looking forward to seeing how the rust will affect my motors when I get it.

Edited December 6, 2018 by KG7UAT

[stix]

I did like the laugh @ approx 35 seconds in. It sounds like the laugh of someone who enjoys what they see, but can't quite put it into real words.

 

Creating rocket motors and seeing the results, is very very very addictive. Hopefully, mostly where they don't explode. But the occasional explosion?... well it has it's merits.

 

During testing, I advise to test your motors "vertically". Simply use a small bucket of sand (or similar) and make a vertical hole in it, and bury the motor up to the nozzle. This will allow some "tolerance" in that any explosive force would generally be directed (harmlessly) upwards.

 

I'm not sure if that makes sense. If not, please put forward any complaints to the manufacturer.

 

Take care.

[dagabu]

I agree with Stix but I do like to use a forstner bit in a log to put the nose of the rocket motor into when test-firing, since I use paper I'm not concerned about shrapnell and like to see what happens during the burn on video. To each his own, but it is great to see what that motor is doing on a test burn.

[stix]

Thank God his "donga" didn't get in the way.

 

 

[KG7UAT]

Haha yeah, that laugh. That's my success laugh Sure enjoyed that explosion. Well, it didn't actually explode. The kitty litter end cap disintegrated violently, shooting the tube, nozzle first, to who knows where. When watching it frame by frame, the tube is just barely seen in two frames before disappearing. I was shooting in 240fps, so that tube had to have been moving at a bullet's speed.

 

Thanks for your suggestion. I used to secure the motors in a vice, but stopped doing that because the combination of heat and pressure caused the tubes to deform. When I built this core burner, I didn't expect the results that I did, so I didn't really prepare well enough. Recently my motors hadn't gone anywhere so I didn't expect this one to be any different Man was I wrong

[dagabu]

The good news is that you have motors to test! Regretfully, you have about 99 things that can affect the motor and cause 'rapid unplanned disassembly' which you may need to figure out before you have a solid motor.

 

I do have a top 10 things that make a motor go BOOM! list if you like?

1. Paper Crush; your tube fractures from the inside, this comes from a poorly made tube, no tube support or too much pressure.
2. Oversize Increments; fluid dynamics demand that you keep the depth of powdered materials at 1 increment or less or all the compaction pressure just goes to the tube walls.
3. Radial Grain Cracks; pressing with too much force can cause the tube to wrinkle (a whole other thread) and as it relaxes, the increments pull apart causing WAY more fuel grain surface then the casing can hold the pressure of when lit.
4. Longitudinal Grain Cracks; caused when a motor is dropped, twisted off a spindle, abused or not aligned on the spindle while pressing.
5. Spindle Length; if you make a whistle rocket, you are going to be limited to a certain spindle length, any longer and you get all BOS! Make poor BP? No problem, get a very long spindle...
6. Nozzle Throat; all that energy in the form of gas and flame is going somewhere, if it all goes out the back side in a uniform manner, you may get a nice lift of a shell, if the throat is to small or the throat is too long, the pressure may not get out in time. BOOM!
7. Hammer Time; if you pound your motors, are you using the same force on every strike? With a press and listed pressures (loading pressure) you will get better results, you may have to use tame BP if pounding rockets.
8. Bulkheads; we don't need no stinkin' bulkheads! Clay bulkheads are all the rage but may not be necessary, if your powder burns at 3 seconds an inch and you are making a 1 pound motor, perhaps just use your BP for the delay? Clay bulkheads are tricky, you have to press them on top of your fuel, if you are getting wrinkles in your tubes, your bulkhead may not be seated, fire may get around it or even push it out of the end.
9. Light Me Up; where you put your fuse will determine the internal pressure upon ignition. With tame BP, you can stick a fast fuse up to the end of the core and make the most out of a slower fuel. Try that with HOT BP or whistle and you had better have a jacket and glasses on and ear plugs in! A simple "J" hook of a piece of visco is often enough.
10. Better The Devil You Know; tooling is expensive, a lot of use like to start by making them ourselves, "How hard can it be?". The simple fact is that your buddies are using tooling made by Caleb or Ben, all the dimensions, tubes, data and formulas have already been proven. Still, many have to "learn it for themselves" which is fine but sometimes at a great cost.

Good luck and Godspeed

[KG7UAT]

Thanks dagabu! That should be handy. I'll copy that into Notes, if you don't mind, for later reference.

[dagabu]

It's really for black powder rockets but the ideas may inspire you to find solutions to you issues with sugar rockets.

[MadMat]

There is one more thing to consider for CATOs .... the diameter of the core. It may seem unusual, but if the core diameter is too small, it can cause the tube to explode. Make sure your cores are the same diameter as your nozzle throat. Of course most cores (if using tooling and not "drilling them into a completed engine) have a slight taper to them , but at the bottom, the core HAS to line-up and match diameter with the nozzle.

Edited December 7, 2018 by MadMat

[KG7UAT]

Thanks MadMat. My cores are the same size as the nozzle, but I think my nozzle is too small because my motors are still exploding.

 

Thanks so much for your help everyone! I'm having soooo much fun!!

[dagabu]

Sugar rockets, MM?

 

I have to say that my experiences differ from that, when making a sugar rocket with bates grains, I have found a core as small as 2 mm is enough to get the 'fire going' but it does not increase the pressure at all, the surface is just too small to build that kind of pressure.

 

Now... if you are combining the core with the nozzle diameter then I understand but the two may not correlate. In fact, pressing a sugar rocket with the proper nozzle then using a rod to make the core smaller than the nozzle diameter is a good way to 'sneak up' on getting a very light rocket off the pad without blowing the fins off. No need to match them up size for size.

 

 

Edited December 7, 2018 by dagabu

[dagabu]

KG7UAT,

 

There is a lot of things to consider when making sugar rockets, from casing selection to nozzle material, from chemical grinding to grain pressing etc. I strongly suggest you read through Jacobs site HERE and and James site HERE .

 

They both have loads of information and can help you forge your way through all the information and come up with an idea that works for you.

 

One note I would like to make before hitting the post button, PVC is a horrible casing material. A lot of people argue that it is not but considering that it shatters when over pressured, becomes plastic (soft) at 200 degrees F and will never hold a bulkhead long enough to get a good burn, I would look at paper for your trials.

[KG7UAT]

Thanks that should be very helpful as well!

[stix]

Put safety at the top of the list.

 

Whatever interesting and enjoyable reasons, please be careful.

[RedAir]

Posting on an old thread here, but have you checked out Richard Nakka's SRM excel spreadsheet program? I learned a lot from that.