1lb Rockets Failing - I Need Help

[calebkessinger]

That clamp looks fine. You wanna little baby gap. Most folks don't usually split BOTH sides of the tube. Just cut down one side with a dremel tool or one quick cut on the table saw.

I don't see why it wouldn't work just fine like that.

You don't need a torque wrench. Just a little practice. Soon you will have no troubles. It just takes time. after a while it becomes old hat, You'll get these rockets down, go to making different rockets and then the gremlins will start rearing their ugly heads.

[joeyz]

thanks for the confidence caleb, you da man!

 

herr is another update, i just pressed a rocket. the tube was 7 1/2" long to match the 7 1/2" 1lb core tooling in the above pictures in the clamp. i lost a 3/8" during pressing, see below photo (top of rocket). after releasing clamps, it slowly expanded back to 7 1/4". probably an hour from now, it will regain its full 7 1/2" erection, hahahaha

 

i think i figured what the miner light surface cracks are, tube compacting then retracting, and doesnt look serious to me to worry about. i guess your always going to get shrinking in tubes when pressing big rockets at 2,000+ pounds.

 

neighborJ, thanks for alerting me to examine length before and after pressing. i better understand compacting and retraction. ihad the clamps tight until i could barely pull the rammer with the pull bar.

 

Rocket tube collapsed to 7" during ramming.

 

tube was original flush at top of pvc, 7 1/2" length.

 

rocket regrew to 7 1/4" in length.

 

rocket continued expanding length to 7 3/8".

 

normal i presume.

Edited August 26, 2016 by joeyz

[calebkessinger]

That tube looks fine. I wouldn't be worried about it if it was a whistle rocket or something else.

 

I am amazed it shrank that much. and came back.

are you pressing them at 2000 on the gauge?

[joeyz]

yes sir, 2000 on the gauge. agreed, not worried, going to fire it lol Edited August 27, 2016 by joeyz

[joeyz]

the outside tube and inside pvc surfaces are booth real smooth, i could rough (course) up the inside pvc to prevent sliding.

[NeighborJ]

I roughed up a support once and it delaminated. The inside of the tube got pushed down inside the tube by about 1/2", it was a 3# motor but it catoed. I decided not to do that anymore. It was about that time when I started waxing the tubes, but only the ones I was having trouble with.

On bp motors that shrinkage is normal, and like Caleb said if it was a whistle it would not get fired. I had a big Cato last night with a 4# whistle which had a questionable wrinkle on the side. Never again, that was the biggest Cato I've ever had. My ears were ringing from 50 yards away and I felt like my nose was gonna start bleeding. If I have any doubts I'm crushing the comp out and starting over.

The bp doesn't form a rock hard grain, it remains a little spongey and this helps when the tube relaxes. The biggest problem you need to watch out for is to make sure you line up the nopass lines with the support and not the tube.

[joeyz]

thanks neighbor, i lineup my no pass lines on the pvc top because its exactly 7 1/2" for that 1lb toolset and i use the pvc also as a tube length template to cut.

[DavidF]

That is an insane amount of shrinkage (and 'relaxation')! My first guess would be that your increments are too large. How big a scoop are you using? Also, don't forget to clean out your drifts. Do you hear noise at all when pressing?

[NeighborJ]

DavidF if I don't hold a dwell my tubes will shrink a lot as well, but mabe not quite that much. I was assuming extra shrinking was due to spiral wound tubes, and no waxing? I know he's got good tubes which can handle the pressure, but I'm curious about this issue. I'm waiting to see what happens when he test fires.

[joeyz]

i did one level teaspoon or less, about 20 tspn during the duration of the build. yes, i always check rammer holes and clean after each press. i am going to do the same steps again with a non spiral tube to see if spiral tube is the reason. but i think the next tube wont shrink because its much thicker. going to test tonight, the end burner and core burner spiral tube rockets i made and see how it flies. i dont think it will have any problems but we will see.

 

if composition is too damp or powdery, could that cause shrinking of tube when pressing? but i dont think my mix is damp or dust dry but it is not granualated either and that can play a factor?

Edited August 27, 2016 by joeyz

[DavidF]

Hey, I don't want to say anything bad about Phil's tubes because they all worked for me in every test I did. That said, you guys know I like to wax my tubes. Not just my Phil's tubes- all my tubes. And I don't know where guys come up with having to clean large amounts of wax off of drifts and inside the tube. I use a Scotchbrite 'soft scrub' pad to wipe any wax off my drifts. EZPZ. If it's not applied too thick, barely any gets on the drifts. The wax must be very hot. Also, you don't HAVE to wax the whole tube. You can fill it most of the way, flip it over, and press your nozzle in the dry area.

 

The next thing I wonder about Joe's motors, is how tight are the drifts in the tubes? Phil's tubes were available before in IDs of .750" and .765". The .750 would be good for end burners because they require a good snug fit between drift and tube so the spindle doesn't get grazed in the beginning. BTDT. And waxing those tubes makes for a pretty tight fit, yes. For cored black powder motors (and also the flat end burner drifts), I like a sloppier fit. The .765" ID tubes are just right for a .750" drift, in my experience.

 

Waxing Phil's tubes will definitely reduce the shrinkage, but I could not say for certain it is even an issue.

[calebkessinger]

Whistle Catos are the BOMB !!

 

I need to get myself another press put together so I can MAKE SOME ROCKETS!

 

Getting the bug.

[dagabu]

Just got home from Boomtown and started reading this thread again. I say "to each his own" but I do wax my tubes and use a funnel that only allows the wax up to the last 1-1/2" of the tube so the nozzle can bite in!

 

Messy? Nope, I have a rammer, 4" longer than the tube, its been turned down 0.002" and the end has been peened (thanks SLD) so that only a sharp edge touches the inside of the tube wall. This is simply pushed through the tube after the wax has been poured and the wax lining is incredibly thin and does not get on any of the rammers.

 

P.S. I made two end burners with Phil's tubes, waxed the tubes, stayed with 6500LPI on BP, standard Caleb's tooling, launched them and BOTH got 20-30' up and came apart at the seam. I am really saddened, I have to get more and try again.

[calebkessinger]

hmmm...

gonna have to get me another press assembled and work on some more endburners with phils tubes.

[NeighborJ]

In davidfs YouTube video about his brass tube support, he uses a wet sponge to wipe down the outside of the tube so it can grip the support. I wonder if this trick would help Joey keep the shrinkage and relaxation down. I had always assumed he did it only for his support so the brass can catch the tube when tightened but mabe he does it to keep the tube from pulling down. Hopefully he can chime in and elaborate.

[DavidF]

I do just do it so the brass can catch the tube when tightened- that I know of. Maybe it does help keep the tube from pulling down. NEPT tubes have some residual dextrin on the surface that might aid in that. At least the old ones did. The new ones seem to have quite a bit less dextrin. But still, the tube does temporarily swell when the surface is moistened.

 

As Caleb pointed out, Joeyz is the only guy that splits the PVC in two. Another variable that could have an effect. Another thought that comes to mind for the pulling down is dwell. More dwell gives greater compaction of the propellant grain. This would pull the tube down more at the same time. I just can't imagine 1/2" of pull down! Grasping at straws here When I press with the arbor press, I use the P to F gauge to set my torque wrench. Then I just use the torque wrench. Watching the needle on a P to F for every increment is no fun. Also, when torque wrench pressing, if you pull slowly (more dwell), it applies more pressure before it clicks. I pull mine briskly. There's a lot to consider just in the ways different pressing methods apply the pressure. Of course, when we don't have problems we don't consider those things

 

Picking it apart a bit, what about this: With a PVC support, the support is flexible, and to some degree, compressible. When an increment is pressed in, it stretches the PVC a tiny bit as the tube of comp expands inside it. This might make the PVC support just a bit more loose for the next increment, encouraging the tube to pull down. The brass, on the other hand, has no perceptible give. Steve LaDuke is the one that came up with the relaxation theory (at least in those words). Steve LaDuke uses PVC supports.

[dagabu]

I use a combination of solid supports and brass shim stock sleeves, I can press two drivers, side by side, one in each support and put them on the ACME and the graph is very nearly identical.

 

For the tube pulling down, I find that any powdered comp in larger increments pulls further while granulated comp has much less tenancy to pull down. For me, dwell makes no noticeable difference on the pull down but makes for a solid grain in an end burner when I hold it at the 6500LPI for 15 seconds. The pressure spikes diminish greatly.

 

Ill be looking to get a full order of Phil's tubes for another look at endburners but at this time with VERY limited research, I cannot recommend them for use in a dola.

[joeyz]

DavidF, dag, caleb,

 

Points well noted and i value your comments and the time you take to help me.

 

CUT PVC

Bought some new pvc today and going to make a single cut opposed to double cut. Being new to rocketry and tooling, maybe the double cut is a contributing variable, allowing the rocket tube to slide. A one cut is sounds logical, think it wraps tighter. Making thise changes tomorrow.

 

GRANULATING BP

Another possible variable. My BP isnt moon dust or dusty but it is kind of like flour or when you coffee grind sodium nitrate "caking" and extremely easy to compact. I think you have something there with granuals being crushed on top oppose to cake bp being easily pressed to where it immediately pressures the side walls. Sounds like uneven balance or force distributuion during pressing, my bp has no structure, easy to flat. Going to try and improve this tomorrow by granualating. I assume you guys do it the way you granulate any bp, wet it down enough to form a dough ball, tear off chunks, rub or press through a mesh and let it dry. Another option i can try, attempt to minimize the caking, is to spritz alcohol into the container and shake the heck out it. Even though alcohol is not a dextrin, its properties does pull and bind particles closer, tighten up, shrinkage if you will. That should harden things up to where its not like clay. My current rocket bp is like a clay and easy to cake. Does any of this makes sense to you or am i thinking wrong? I am starting to believe my bp is too soft like bentonite clay cause it sure feels like it to the touch and pressing.

 

In ned gorski's youtube vid on making rocket bp, the only step i missed was spritzing with alcohol/water. I was out of alcohol and just used water. I think there was my mistake and got clayish bp pulling down on the walls during pressing.

 

If anyone needs to shrink tubes, just come see me, i show you how to shrink 1/2" hahaha

Edited August 31, 2016 by joeyz

[NeighborJ]

Tube Shrinker? That might just work, the last time I cut my tubes 3 times and they were still too short. That sounds like a handy tool, I could keep it next to my tube strecher, it'll be a kit.

You ever reported back, did the shortened motor fly?

Edited August 31, 2016 by NeighborJ

[DavidF]

Joeyz, the granulation is very important. It seems like you might be about to head down a risky road here. If you granulate with ethyl/methyl/isopropyl alcohol, and make the glistening putty ball, that's OK. You could even use acetone. Different alcohols have different percentages of water. The more water in the alcohol, the harder the resulting granules will be. If they are too hard, they won't consolidate fully. There will be microscopic firepaths that cause CATO- especially important in your case, since you are using low pressing force.

 

Straight alcohol makes soft crumbly granules in my experience. But, my denatured alcohol is different than yours. The SLX brand Ned uses is about 50% methyl alcohol. The vapors are toxic and explosive, not just flammable. Ned gets harder granules with his SLX though. Just a heads up on that.

 

Dextrin is only useful for water granulation. Dextrin-bound water-granulated black powder has hard durable grains. It's suitable for lift or burst- not rockets. Now, Steve LaDuke swears by dextrin for rockets. BUT, he does not make the BP wet and into a ball. He makes it moist like brown sugar, and screens it and dries it. Screening it halfway through drying is a good idea if you go that route. I wouldn't use dextrin at all though, if I was you. You don't have enough pressing force to be sure of adequate consolidation. OTOH, you are moistening your powder before pressing. That softens the grains, so dextrin might be OK to use. But why risk it?

 

While we are on the subject of using expensive, flammable solvents for rockets: I may have mentioned before that I like to granulate my BP for rockets with 2% wax, dissolved in pre-heated naphtha. The wax aids granulation and makes the BP press like a dream. If you are considering solvents anyway, you might think about using wax in naphtha.

 

I think your simplest and cheapest course of action would be to semi-granulate with water only (no dextrin), and to re-moisten the dried product just before pressing. Sometimes I like to put the container of BP on the scale and weigh the water as it goes in.

 

Here's another 3 things to think about.

 

1) You will have the most success following one rocket-maker's method ONLY, at a time. We all mean well, but different rocket-makers do things differently. Mixing and matching bits and pieces of other guys' processes into one 'perfect' process is likely to cause problems. You can do that after you get more experience. As an example, if you follow one of Ned Gorski's tutorials to the letter, success is practically guaranteed. But, getting 15 opinions from a few of us guys instead is like taking the scenic route to your destination- and some people like the scenic route! But it takes longer. Just sayin'.

 

2) Talking about end burners and coreburners at the same time is also likely to end in confusion. They are completely different kinds of rockets, burn in different ways, and (can) fail in different ways.

 

3) This is the most important observation, I think. There is black powder, and there are black powder rockets. Whoever came up with the term 'black powder rockets' has certainly caused a lot of confusion. I can say this now, because they are long dead by this point. In almost all cases, the 'black powder' in rockets is not black powder at all. Yes it is black, and yes it is powder. But it ain't black powder! Sure, somebody can be a smartass and mention using fuse powder or Meal D successfully in end burners, pressed to high pressures. But now they don't have to The black powder-like mixtures that are used to make most traditional-type rockets (coreburners) are more like semi-granulated, adulterated versions of scratch mix than black powder. So, you can see that talking about end burners and core burners at the same time is quite likely to lead to misunderstandings.

 

Lastly, we have all made powders that are no good for our intended purposes. But, there is no such thing as black powder that's good for nothing. We all need black match, and we all need prime.

 

As a newbie, I was totally over-whelmed by the sheer amount of available information about rockets. And now, as a lightly-seasoned rocket maker, I'm doing the same thing to the next newbie.

[OldMarine]

I've followed DavidF's advice and am very happy with the performance of my rockets. Everything from tube waxing to my brass supports to his fuel preparation methods have upped my game considerably! His advice shouldn't be taken lightly.

[DavidF]

Geez, thanks OldMarine, your check is on the way

 

I guess I should add one thing to all that rambling. I'm looking at Joeyz's 'black powder' as hot charcoal mill dust to start with for end burners, and 70-20-10 using airfloat and milled potassium nitrate for the nozzled core burners. The end burner propellant can be used for nozzleless coreburners, but I would use wax in either the propellant or on the tube in that case. My preference would be in the propellant though. I do both now- whether they need it or not

[CrossOut]

I definitely recommend standard 75 15 10 mix milled bp for end burners. They can take super fast burning powders and still won't Cato. I've seen people press flash into their end burners and those things take off like a bat out of hell and no cato.

 

I would also recommend other charcoals for your bp. You would be surprised how big of a difference you get using current charcoal. .. spruce is kind of a mid range charcoal better options include paulinia , plum, hard pine, or willow.

 

As for pressing your rocket, I recommend ricing your bp without dextrin. Works for me like a charm and no mess!

 

I would recommend ditching the water and clamping / pressing or hammering you're rockets tighter. Water can cause problems of your motors aren't drying completely or if drying caused the fuel grain to crack. Using the riced no should solve your problems with the mess and using enough force pressing the rockets will solve the powder not sticking. A tighter press also allows for faster burning fuel as well.

 

Your 1 ton arbor press might not be providing enough pressure for your rockets.. I would recommend grabbing a rubber mallet and giving each layer a solid 5-6 hard wacks. You would be surprised how tight of a pack hammering can get. I hammer my 3lb rockets no problem. You will definitely need to clamp your motors for this technique. I've split 1/3" walled parallel tubes so many times.

 

I'm not sure about your sputtering. I do notice this happens with most with energetic fuels like whistles which could be a cause as well as the nozzle dimensions. That is purely speculation tho. I think it sounds cool. almost like strobe rockets. But obviously less efficient.

 

What is the length of your spindle? It should be abouy an inch.. as a general rule, I always press my nozzles to be the same thickness as the diameter of the motor in your case 3/4" thick. If you have an inch long spindle, that will leave a bp core of 1/4" which will provide more l initial thrust for your rocket to take off.

[joeyz]

thanks team!

 

and thank you davidf, marine and crossout. i do value you comments.

 

Davidf,

you are so correct, there are so many areas in rocketry to master and didnt mean to mix apples with oranges by addressing multi issues with end burner and core burners, i see that now that there are so many factors that can contrbute to rocket catos and learning to slow down. because of my schedule (working two jobs), i try to knock out as much and when i can. im great at multi tasking and probably have too much energy. im getting better tin this new rocketry hobby. you guys helped me lots and i think im at the final stage of basic rocketry. the knowledge and data you guys have is amazing and i never realized how a rocket can be sensative to cause a disaster due to tools, fuel and practices. but it all makes sense, we see what simple shrinkage/expanding of o-rings did to the space shuttle.

 

tooling/tubes:

i seem to be straight now in this area. all of my issues involving rocket tooling, tubes, spindle and nozzle technical issues and best practices seem to be resolved thanks to all here, especially dag, caleb, davidf, neighborj and others. i learned/know so much more now than ever before and made so many changes in that area. im definately loving caleb's high quality tools.

 

fuel/pressing: (interesting story that i may have self identified and contributed to rocket catos.)

my focus now has been on rocket fuel for i think its the ground zero and most important. im lacking in this area and still learning fast thank to you guys. i fixed the types of fuel mix ratios to be used on end burners and core burners. you guys set me straight that not all rocket types burn the same fuel. but something hit me this week while making a batches of stars and ran across an issue of them not burning right. they were periodically spitting/popping during testing and not a smooth even sizzle burn as pyro guy would recognize. this tells me i have what i call a "dirty mix". then it hit me, could this also be linked to the rockets i pressed in the video you saw with simularities popping and spitting (car engine back fire)? i usually coffee grind my nitrates and sulfer and run it through a few times back and forth through a normal hand held mesh screen (i got years ago at walmart) and call it good. i call it good because in the past i tested how well the grinder works by testing small batches on a fine steel fuel filter i had and there wasnt a need to further fine mesh my formulas any further and water breaks down the rest during final mixing.

 

as i mentioned, did this for a few years and never hand trouble with stars, strobes, comets, meteors etc popping/spitting (car engine backfire), so something isnt right, my formula is 100%. so i examined my hamilton beach coffee grinder and discovered the 3/8" round and thick plastic washer beneath the dual blade shaft is worn and only a quarter of it remains. this tells me that the rest of the thick plastic washer was shreaded up and somewhere in my rocket fuel. i also examined the blade shaft and it wiggles around 1/2". hmmm, i wonder if its breaking down the chems right to true air float state. i didnt have my fine steel fuel filter screen to test. i cant find mesh screens in my area (lowes, depot, ace), so i went out to a local asian store called OMART. its just like WALMART but an asian walmart (oriental mart) that carries wide amount of chinese, jap, korean, phillipean etc imports. i bought their cheap cooking steel mesh utensils of finer meshes and ran those two large batches of core burner 70/20/10 and end burner 75/15/10 fuels through it. discovered salt size kernals (or greater chunks/rocks) of nitrate, sulfer and unknown black chunks (plastic?) that i could not push through screen. this tells me few things. the black chunks is the shreaded washer and the the wiggling of the blade is not correctly air floating my chems. SEE PHOTOS

 

walmart screens in bottom, new omart screens top (much finer)

 

Dirty fuel, faulty grinder discovered

 

so im thinking my dirty mix is causing my issues. i think when fire hits those chunks of nitrate, sulfer and plastic it causes the fuel performance issues simular to an engine running dirty fuel (irratic idling, popping, spitting, stalling, back fire). So we might have the evidence causing chuffing, maybe its not the swirly inside tubes.

 

so today, before seeing replies on this post, i went through and cleaned BOTH of my dirty rocket fuels through a variety of meshes and got both batches cleanup of plastic and grinded down the sulfer and nitrate chucks through mesh with spoon. i finished granulating the end burner fuel, stired it down with about 1 ounce of alcohol (50% iso) and riced it on cookie sheets and texas sun dried up quickily. fuel is now crunchy like cereal but easily crushable between two fingers. i havent done the core burner batch yet. i will do that tomorrow but now that i saw your guys reply, will use just water as you recommended.

 

as for dextrin, i never used it in my rocket fuel batches. i never had a need to use dextrin in my bp lift or burst for mortar shells and didnt see a need in rocket bp either. the only time i really use dextrin is in star compositions that need it. but i always use (50% iso) in my bp lift and burst so i thought it wouldnt hurt my rocket bp either after seeing ned using it. however, now i realize he maybe using a different type. but if alcohol modifes the rocket bp and performance, increase of cato risk, i should probably not use it all, i can easily work with water. i can see what your saying about alcohol and is probably a contributor why i have fastest black powder in texas. my bp is so fast (like flash) that i had to tone it down or stop using it, decrease my lift amounts or use less powerful batch. my 3" shells were going higher than commercial 4" shells lol. but totally awesome for burst charges or steel tubes for red, white, blue chalk dust in air for nationa anthems or excellent donot gas rings (UFO). so i definately dont want to make bp rocket fuel over potent. will wait for your reply before wetting down and ricing my core burner fuel with just water tomorrow. meanwhile, going to go out and find a new or better coffee grinder.

 

End Burner Fuel, cleaned dirty fuel,through 150-200 mesh, wetted and granulated with 50% iso

going to press a rocket and see if granulation cures tube shrinkage and label changes (clean granulated fuel with 50% iso and to our test video.

 

 

i still have the other 2 core rockets and 1 end burner rockets before all these recent corrections were made to fuel. tomorrow i will press 2 new rockets (1 core and 1 end burner) and label them. today i built a new cool rocket rack (galvenized 1/2" pipes). neighborj, going to take all these rockets tomorrow, put them in rack with labels and narrate these 5-6 rockets as i shoot test them and post video for you guys to analyze. this not only helps me but helps everyone here. your either going to see a stick bomb, joe's mini strobe rocket (dirty fuel) and/or successful lauch lol i think you guys will have a blast watching me screw up.

 

again, thank you all for your help, truly appreciate it. have a wonderful friday, stay thirsty my friends!

Edited September 2, 2016 by joeyz

[dagabu]

Outstanding! Keep up learning and experimenting, can't wait to see your video!