Not so happy rocket launch

[Sparx88]

Um, yep, it happened. Took my time with it and did almost everything the same as far as the motor goes. I did'nt add any alum to the bp this time as it did'nt do much for a tail on the last one. It shot straight through to the can. Too hot of bp I'm thinking as well as not rammed very good. I mean I was'nt going easy on the ramming about the same as the last one but this tube's I.D. was a little larger maybe .5 mm so the tolls were a little tiny bit loose fitting. So maybe the whole column of rammed bp was pushed up and out while the rocket went up to the right, and shot the can up to left. That was supposed to happen as I had a small charge at the top of the rocket to shoot the can a little higher with a report then the can burst. These are just best guess. I WILL NOT, give up

 

 

 

 

https://www.youtube.com/watch?v=BzYPPqfB4c0

[OblivionFall]

Hey, at least it still shot the heading into the air

 

I'm no expert on rockets but I remember reading somewhere that Hot BP is used to make endburners with no nozzles. Ramming could have definitely been an issue. If you try again and find that Ramming isn't the issue, maybe try a larger end burner hole?

[nater]

Did you use a bulkhead? What did the remains of the motor tube look like?

 

Oblivionfail - hot BP is used for end burners WITH a nozzle or nozzleless coreburners.

Edited April 27, 2015 by nater

[FlaMtnBkr]

I forget, are these core or end burners? If core, how much comp was rammed above the top of the spindle? In other words, how big was the bulk head? Was it all BP or was there clay added?

 

It's hard to tell but it looks like the bulk head may have blown thru causing it to end early as fire got thru. A 1 ID bulk head above the spindle is a good starting point.

 

Maybe work on getting a reliable motor going before starting to put headers on. You can crank the motors out a lot faster if they don't have a header and you won't feel bad lighting them during the day. If you want something, 1g of flash makes a nice report that isn't too obnoxious.

[Sparx88]

Did you use a bulkhead? What did the remains of the motor tube look like?

 

Oblivionfail - hot BP is used for end burners WITH a nozzle or nozzleless coreburners.

I top them off with a clay bulkhead about 1/2" long since these are 7/16 id tubes. I hand drill an 1/8" hole in them for you know, fire transfer. I don't want to sound like I have been doing rockets for any length of time. Truth is I just started a month ago making rockets. That equals a whole half dozen Oh yah, I took some pics of the casing and stick. I was surprised to find it only 4' away from the launchpad still intact. Think maybe that adding that 1 1/4" core was a no no? I commented about that in my previous rocket success post down the way abit. I added at my best guess a 3/4" x 1/8" with drill bit. I tried a 1.5" x 1/8" on another previous rocket and it went bang. So I thought trying something in the middle would work out. Seems that it should, I keep coming back to the idea that the tube was'nt as solid as it should be and the fit was loose. Therefore when ignited the pressure swelled the tube and caused the nozzle and bp to come loose?

 

 

 

I forget, are these core or end burners? If core, how much comp was rammed above the top of the spindle? In other words, how big was the bulk head? Was it all BP or was there clay added?

 

It's hard to tell but it looks like the bulk head may have blown thru causing it to end early as fire got thru. A 1 ID bulk head above the spindle is a good starting point.

 

Maybe work on getting a reliable motor going before starting to put headers on. You can crank the motors out a lot faster if they don't have a header and you won't feel bad lighting them during the day. If you want something, 1g of flash makes a nice report that isn't too obnoxious.

your right I need to focus on the motors more first. I think that the bulkhead and nozzle failed. Hope the pics help us figure this out.

 

[FlaMtnBkr]

I read the other thread but still not sure exactly how they are made.

 

It can take a little bit to make a good strong tube. It obviously didn't burst but is there a line or gap on the inside where the paper starts and fire could flash along? Are you using a board when making the tubes to roll the tube and tighten the paper on the mandrel? If not could the tube be bulging and allowing fire to get between the grain and the tube? Have you heard of waxing tubes? A layer of wax is applied to the inside which helps stop that last thing from happening. It's fairly new but a search should yield enough info.

 

Since you are using your regular BP that is hot, maybe try not using a clay nozzle and making nozzle-less motors. A long core gives it power and you don't have to worry about the nozzle as much or how long the core should be. I think 7 ID's is the normal spindle length for BP tooling, and 10 ID's for the tube length.

 

Are your BP grains very hard? Is it pressed and corned or plenty of binder? Hard grains make ramming difficult as it doesn't compress well and leaves cracks in the grain. Are you ramming in short increments around 1/2 ID or less? More can leave sections that aren't compressed well. I rice my BP without binder which gives durable enough grains but will compress nicely when rammed.

 

It could be any of these things and probably others I'm not thinking of. Since it looks like the nozzle and bulkhead blew out I would look at the full strength BP while using a clay nozzle as being the cause. Either make weaker fuel, don't use a clay nozzle, or don't drill a core and stick with an end burner. That's what I would look at first personally.

 

Good luck.

 

Edit: clarification

Edited April 28, 2015 by FlaMtnBkr

[Sparx88]

I haven't tried using the granulated bp since the first rocket. I made it an end burner with nozzle and it exploded instantly. I have been using the milled powder. same hot bp but before ricing. The good rocket in the other thread had it in there. Waxing the inside of the tube sounds great. Makes perfect sense. I assume avoid waxing the ends where the nozzle or bulk head goes. I have a couple more tubes made up. Shorter ones though. I'll make one an end burner with nozzle and the other cored without nozzle. Then I suppose I could give the granulated another try. It's some wicked bp and that's being modest. Should I just go ahead and break some granulated back down to a powder and do that?

[FlaMtnBkr]

If you don't mind working with the mill dust you can use it, it's just normally a bit messy. Some people add a little oil to keep the dust down and help with compaction and TR the rocket master even uses a small amount of water. So you can keep using it if you don't mind working with it and maybe make some granulated without binder next time you're making BP.

 

I haven't tried the waxing yet but it does sound like it has multiple benefits. I know people are waxing the whole tube and a few people wondered the same thing but found the clay bites into the wall about the same and it's not an issue.

 

Something I just thought of. Are you pressing the clay all the way to the very end of the tube or are you setting the tube on a 'tit' of dowel so the clay plug is recessed an 1/8" or so? When it is recessed it creates a bulge that is narrower on each end to help keep plug in place. If it is flush with the end it can come out easier under pressure. Are you using ground up kitty litter for your clay? Depending on the brand, hardness, and granule size you can add 15-20% of the granules to the powdered clay and it can help bite into the tube when ramming.

 

Give the two types of rockets a try and see what you think. Remember that end burners can't lift a ton of weight depending on what you want to do.

 

Edit: I type fast and it seems to make sense in my head while I'm doing it but it's not easy to tell what I'm replying to. Guess I need to make better use of quotes though it isn't real easy on the phone. The phone also likes to auto-correct and that doesn't always help. Anyway, if something doesn't make sense just ask what I was trying to say if anyone is interested.

Edited April 28, 2015 by FlaMtnBkr

[pyrokid]

I second the recommendation for nozzleless core burners. I don't know if tooling is too readily available.

 

I have been making 1/2" ID x 2.625" L core burners, and they lift 50g using only a bbq skewer as a stick. Approximately 7.2g mill dust is the fuel.

 

Tube is super simple: I take two strips of 8.5x11 paper, 2.625" wide x 8.5" long, stack them, roll them dry onto the mandrel, and use a single piece of scotch tape to secure the outer layer.

[ddewees]

I would concentrate on making a decent tube... If none are available to purchase.

[Sparx88]

I'm just about there. Tested 2 more endburn/nozzles and they both worked nice. I have a set recipe for rolling tubes that I have been using for quite a few years. One thing I know I don't want is squishy limpy bubbly irregular tubes anywhere near pyro. I use 60lb kraft, wheat paste with Tight Bond and waxed wood mandrels. The rocket that failed last was a rocket that was made using a softer tube because it was what I had and thought it would work out but. Too soft and squishy, bad for pressure. My tubes when dry are rock hard and they bounce when you drop em. I don't stack layers I roll each layer seperate until desired thickness. That way there is only a 1 layer thickness line or gap on the inside of the tubes that could cause fire to pass. I used the wax idea on one of the 2 I tested and noticed no difference. Though a safegaurd like that would help eliminate the 1 out of 20 motors that might have an issue where the wax would help. So I suppose that's all up to who's building if they want the extra steps or instead the risk. I have a nozzless core burner drying, used the spritz(s) of water trick mentioned and it really gets the bp packed tight and super smooth. Just wetted enough so that it would still fall through the funnel. I'll film that one along with another end burner tomorrow.

[Wiley]

Care to share how you roll the tubes?

[Sparx88]

Sure not a problem. I'm honored to. We got rained out so no videos until later today or Saturday. That'll give a chance to get all 5 done. Edited May 1, 2015 by Sparx88

[dagabu]

Um, yep, it happened. Took my time with it and did almost everything the same as far as the motor goes. I did'nt add any alum to the bp this time as it did'nt do much for a tail on the last one. It shot straight through to the can. Too hot of bp I'm thinking as well as not rammed very good. I mean I was'nt going easy on the ramming about the same as the last one but this tube's I.D. was a little larger maybe .5 mm so the tolls were a little tiny bit loose fitting. So maybe the whole column of rammed bp was pushed up and out while the rocket went up to the right, and shot the can up to left. That was supposed to happen as I had a small charge at the top of the rocket to shoot the can a little higher with a report then the can burst. These are just best guess. I WILL NOT, give up

 

Think about the additional thermal energy needed to ignite all of that aluminum then think what additional power you have without all that aluminum... It may not have been the ramming.

[Sparx88]

Care to share how you roll the tubes?

Ok, now this is how I do them for most things. Back when I was still doing 1" and 1.5" shell farts like the one on that rocket for cakes, I rolled the guns and shells. Same method now. Not really a "method" or "super secret" lol. It's really all about the paper and the glue. How you go about using whatever mandrels you like and how you keep the rolls tight is up to you. What size you need etc. for me, it's -virgin 60 lb kraft- I get at office depot they come in 3' x 15' rolls. The glue is 50% standard wheat paste(already made), 30% Tight Bond, 20% water to thin. I just have my strips cut and start painting them with the glue on both sides, with aluminum foil spread out for a work surface, and keep the strips wet until they have turned dark brown and have absorbed as much glue as they will. Note----wait too long and the strips will tear easy. That goes for any paper. I roll 1 strip at a time. No matter how many a tube needs for desired thickness. With well waxed mandrels the tubes slide right off as long as you gave the strips one last paint before rolling to re-wet them. They should'nt be allowed to dry at all during the glue stage anyway. Then just give them a gentle wipe off the excess glue slop and dry them slow. No fans or heat. In fact here recently I have been drying them on waxed dowels/mandrels once the surface wet has dried and just slid them back on. Then, you can dry them faster with fans or heat but only while they are back on the mandrels. I buy 4' lengths of dowels at lowes so to have a bunch extra for drying like that is not a problem. Just 400 grit sand them and wax on wax off sort of deal. Thats about it, not really a method or anything. The tubes are strong, rigid and they look nice. Kraft.

 

 

edit;-- on the wheat paste, just to be clear, when I say standard wheat paste already made is I make it myself with, flour, and water, and a nukem-all machine Oh, and for anyone who does'nt already know, you can preserve your glue, or glue like mine by adding a level tablespoon of boric acid per quart. Yep, stays fresh for months and months and no more wasting. Just re-heat until steaming before capping and put away. Helps out. Boric acid kills mold. Oh and does'nt affect the glue's performance in any negative way unless a super chemical guru can point out otherwise, I have'nt noticed any change No stinky nasty glue

Edited May 8, 2015 by Sparx88