Experimental rocket fuel

[NeighborJ]

All these tests have been nozzleless. And I'm slowly coming around to the realization that I'm gonna need a nozzle. These things are getting crazy long and it's damn hard getting the spindle out even with the full taper of a pusher design. I've also been amazed at the lack of catos, even when using a spindle with sali whistle which normally is an automatic Cato for a bp motor.

[NeighborJ]

I've devoted quite a bit of time to the testing and experimentation of these fuels, I've found some neat things but I've not accomplished my goals. I'd like to report to Masterface that I've tested his formula exactly as it is written but cannot get good ignition, only a few loud cuffs. But I've found it will burn quite steady at atmosphere with lots of gas production and slow burn rate. I have been able to use it in place of a nozzle as the first increment of a standard whistle motor, it burns at the perfect speed to allow the orifice to expand very slowly allowing for a neutral burn. It has been instrumental in creating a supersonic rocket, but my sticks can't handle it and so far every one of them has snapped both sticks clean off. I'd like to know how Deweebs keeps his rockets together for his supersonic flights. At this point I think I'll need to use standard delta fins to make this happen.

[dagabu]

...but my sticks can't handle it and so far every one of them has snapped both sticks clean off...

 

Have you used two sticks, 180° apart? It is generally the off center force from the rocket "nozzle" (tube) that breaks sticks, this is easily solved with using 2 shorter sticks.

[NeighborJ]

Yeah Dags,you taught me that trick. I use two sticks on every hi power motor. They lift off arrow straight and somewhere around 100-150' they get real quiet, the sticks break, and I can hear it again as it drops back down to subsonic and quark screws until it hits the delay. They stay attached to the motor and break within 6" of the bottom of the motor. I use hi quality sugar pine,and have tried sticks approaching 1/2" square on a 1# motor. would a different type of wood work better? Mabe oak? Or would it be too brittle?

[dagabu]

Well, I'll be buggered! That should not happen. Any pictures of the broken sticks still attached to the motors?

[NeighborJ]

I left the motors in the trash but I think the exhaust is forcing the two sticks apart. But it's just a theory I tried to videotape it but they are just too fast to follow at a distance it can be viewed clearly. Mabe I should try a large single stick.

[ddewees]

I've had sticks "cooked" off too... It can be frustrating. You end up with that death spiral.

 

[Video]

[NeighborJ]

Ddewees, it looks like you filmed one of my flops because that is exactly what mine have been doing. I think at some point the second stick is hurting my rockets. I think the thrust cone coming from the back of the motor is pushing out on the two sticks until one or both sticks break. The other theory is the stick bend out and snap off as it breaks the sound barrier due to drag. I had similar problems in amature rocketry where either the fins would rip off or the body tube would rip in two, almost like it was cut with a knife. But those were aerotec motors jammed into ultra lite rockets. Those composite c-slot motors have a lot of thrust and would quickly find the weak spots in a rocket design.

[dagabu]

True that, J! Your motors must rock!

[August]

Pine is to fragile IMO. Get yourself some poplar. Might also want to wrap a bit of foil tape on your sticks for fireproofing.

 

Have not heard of sugar pine, but sugar maple would be a poor choice. Red Oak would be better than pine or maple, but not nearly as good as poplar.

[ddewees]

My sticks were poplar... 3/8 inch square. Short too... Only 30 inches.

[NeighborJ]

Yeah ddewees, 30" is a good length for mine as well but I can't believe that only a 3/8" stick is enough. Mine have been around 1/2". I will need to try poplar, I was also considering rotating the stick 45 degrees so the flat sides are not facing the thrust cone, this should keep the thrust cone from pushing out on the stick. I'm also going to try to face the arch of the tree rings toward the motor, this should allow the stick to bend more without breaking.

I have very limited time for these experiments now so I had to put most of them on the back burner, but I will return to them armed with additional knowledge and fresh eyes.

[ddewees]

That's the size Midwest wood specialties sold (used to sell?)...

 

I had a local guy cut me some 36" x 1/2" x 1/2" and they seemed like over kill.

 

Some people love the long sticks... I never cared much for them. Harder to transport, and more likely to snap when loading into tall racks.

[OldMarine]

I don't build whistle rockets yet but use 2 sticks on my 3lb rockets. I use a piece of tape at the ends of the sticks to keep them separated and to keep them from flailing about during launch, I started doing this when I was using white pine rather than poplar for my sticks and it's served me well so I stuck with it.

 

EDIT: With the white pine, some of my hotter rockets would rip the stick off at the top of the launch tube and fly off like a crazed cruise missile. I got tired of running from them since I'm an old fat guy so doubled up on the sticks and connected them at the bottom.

Edited October 2, 2016 by OldMarine

[NeighborJ]

The thinner stick worked wonders. Used one pine stick this time at 30"x 3/8x3/8, added some AL tape below the motor and on top of the stick to streamline it. This one did not go super sonic but close. I feel comfortable juicing the fuel again to start a new round of sonic tests.

The broken double sticks appeared to have too much surface area, causing the exhaust to push out on them.

[August]

Rotating the stick 45 degrees will do nothing to reduce the force the exhaust cone is exerting on stick. Look at the size shadow it casts. Slightly more aerodynamic, but now it has more surface area to push on.

 

I make my sticks rectangular and attach the skinny side to the tube. Reduced force from exhaust, longer burn through time, and keeps the strength.

[ddewees]

If anyone knows anything about sticks, it's August. Good advice.

[NeighborJ]

I wish I could find a book with simple information,like that, catered to pyro rockets. There is an abundance of info on amature rocketry but a lot of the info needed for fireworks is simply not available, except for the sparse and disorganized info sprinkled thru out apc.

Or there are some people who become stingy with their hard earned knowlege, as thou it is their chance for fame or glory. I am a welding instructor and I have never found any benefit to withholding info from my students, in fact, thru sharing, it tends to generate more interest and all benefit. It is always my goal to have the student outdo his master but there is no substitute for years of experience. Over the years there have been a few students who have really given me a run for my money and forced me to up my game beyond what was previously acceptable and I feel the same would happen for pyro rockets.

Sorry about the rant, everyone here has kindly taken time out of their own lives to answer my questions and I very much appreciate it.

[ddewees]

Pyro is kind of different though... It's easy to climax, so any advantage is always a plus.

 

Group shoots and pyro events quickly turn into competitive environments, and giving all your secrets away is never a good thing.

 

I look at pyro as magic, and knowing all the secrets ruins it.

[OldMarine]

Steve LaDuke is an anomaly. He'll share every tiny ort of knowledge he has crammed in his head over the decades on every type of rocket. Tom Rebenklau is also generous with his knowledge but he apparently despises typing and texting.

Dan (ddewees) and DavidF are also very free with their building know-how and neither is afraid to share a failure as well as successes.

I don't think there can be a definitive book on pyro rocketry because the techniques and materials are constantly evolving. These forums are the best repository for rocket info because they are constantly updated and peer reviewed.

My 2¢

[NeighborJ]

Ahh, Steve and Tom seem to get it. It is the tight lipped nature of the seemingly "black magic" which keeps rockets just out of reach for many perspective rocket enthusiasts. By limiting the playing field by withholding info. I believe it is doing the hobby a great injustice. While it may be easy to reach a climax with conventional rockets, it is easy to imagine where the hobby could be if we could selflessly share that info. While my mind can easily reach a roadblock with creativity, it can also identify ways to improve on other peoples creative ideas. I'm not saying you should share every little aspect of the hobby, but it isn't magic, we need people to see this aspect of our hobby and find the confidence to feel they can be capable too. The masters and novices will still be separated by experience and ability. The survival of our hobby depends on this exchange of knowledge and ideas. This forum is imo perhaps the greatest contribution to our hobby of all time.

[calebkessinger]

You can tell someone EXACTLY how you accomplished the most perfect thing you have ever done without worry.. 99.9% of the time people will disregard a step or determine they can do something better and fail to replicate your work.. and even if they do. You have already learned the lessons that got you there and are on to the next challenge Way further ahead of anyone trying to keep up.

 

Here's my new baby rocket tooling i've been fooling with. 2oz.

That's a 3/8 tube 2.75in. long.

[OldMarine]

You can tell someone EXACTLY how you accomplished the most perfect thing you have ever done without worry.. 99.9% of the time people will disregard a step or determine they can do something better and fail to replicate your work.. and even if they do. You have already learned the lessons that got you there and are on to the next challenge Way further ahead of anyone trying to keep up.

 

Here's my new baby rocket tooling i've been fooling with. 2oz.

That's a 3/8 tube 2.75in. long.

Well, damn Caleb, I forgot to list you in the sharer column! My sincerest apology Sir!

[OldMarine]

I look at pyro like I'm venturing into a jungle somewhere. I'd rather someone else go in first to make sure the natives won't eat me and the food won't kill me. I've had enough adventuring in my life.

Caleb, if you give me a method/process I'm damned sure going to follow it to the letter at least until my results match yours and then I may tweak it. Maybe!

[ddewees]

I'm the opposite. I'd rather discover things on my own, than follow a step by step tutorial.

 

Nice baby strobe Caleb, that was pretty cool.