Final steps in making BP motors - seeking advice

March 11, 2020

I was wondering what the heck "waterglass" was. I've seen it mentioned in other threads regarding something to do with rocket motors. I hadn't taken the time yet to look it up. Thank you. IIRC, sodium silicate is the stuff that is used as a threadlocker for muzzle devices for attaching suppressors on threaded barrels. It, reportedly, has a high heat tolerance, which regular "locktite" doesn't have. Thanks for the tip. I will keep this in mind. It sounds a bit sketchy doling it out so that there's enough to do the job rightly, but not so much that it leaks all over the tooling. Sounds like something that should be removed from the mandrel thoroughly, and that the motor/nozzle assembly should be removed from the mandrel promptly.

Good tip on being able to thin it with water, too. I had a really solid success today with my nozzle puzzle and I hope I have found the answer that will work for me. But I'll keep this as an idea to try if my "solution" today doesn't solve things.

Thank you.

--HC

Using that stuff for threadlocking sounds a bit extreme....for the life of me I can not see how the device could be removed from barrel once this stuff sets. One might just as well weld it in place. You are right about the fire reactance, it does not break down of soften even at extreme temperatures. In fact it is used to fireproof wooden constructions....impregnation with waterglass shall render wood nonflammable. Even to the extent where it does not burn in a furnace. I remember a case when construction workers took old wooden beams from a church roof construction and repurposed them as firewood. Turns out the beams were impreganted with waterglass and would simply not burn

Dosing is simple, you use a syringe and figure out the correct volume to add to each size nozzle/motor. Make measuring cups for the clay granules to keep their amount constant too. After that it is just repeating the movements. The nozzle can be pressed in one go when using the waterglass/bentonite composite. No need to do it in several sections. Inevitably some does collect on tooling, but if you scrub it off with water after use then it shall not pose too much resistance to cleaning. Letting it set with the clay for a few days and then trying to clean the residue is hard work.

March 12, 2020

Success-er!

I remade the tooling for the Estes-style nozzle today and pressed a PKL (plain kitty litter) nozzle. Looked AMAZING! Being me, I had to bung up a bit on the machining and it's kind of a pill to remove the motor/nozzle from the mandrel but it works. I got so excited that, while mixing the H2O and BP, I forgot to smash the second half of the charge into the cup I was messing with and then only packed that first bit into the motor (I thought I got it done quickly). Major Dumbass strikes again. I've been me for a while and that kind of junk happens all too often. Anyway, I did a burn test on it (having already put the clay bulkhead in the motor before realizing I was short on BP). It burned very shortly, of course, but it didn't blow out the nozzle or erode it any. I will have to try again and get a longer burn with my "standard" 15g of BP, but optimism is high.

I also pressed another of the hawthorn-grog-wax nozzles and loaded it with BP (15g) then 3g of "delay" mix (60-40 KNO3 to charcoal), then a clay bulkhead, then some fine (-70+100 BP) to fill the hole I drilled in the bulkhead and then some -30+50 BP to near the top and a 1/2 tsp (a little less, actually) light-packed clay plug. A "complete" model rocket motor, my very first. I'm so proud. I shot this one, too. OMG, same as yesterday: flash, whoosh, straight up right quick! Got to the top, slight delay (it seemed...kinda hard to tell...I think these things are hitting 200 feet) and a pretty good POP! I was able to recover this one, thank God. The nozzle looks really good, and the pop charge didn't blow the tube up. I'm not sure I'm really happy with the delay charge/time. I think I need to do some static burn tests on that. I may need a different formula/mix for the delay (I'm all ears if anyone has something better). I also need to find a tune on the pop charge. I heard the report from the ground which makes me think that the pop charge was too much and likely would have blown a rocket body tube open or sent the clay as shrapnel trough a plastic parachute.

The flame formation from the PKL Estes-style nozzle looked different than what I've seen from the de Laval-style nozzles I've shot, but until I can put this into a model with an altimeter, I'll not have any way to know if one nozzle gets better "efficiency" than another.

In summary: plain, non-scoopable, cheap kitty litter, when formed like an Estes-brand nozzle, worked well in a handicapped/limited test. Having a more complicated nozzle form (de Laval) required several iterations of mixes to end at 61% hawthorn fire clay, 31% grog, and 8% wax (heated and mixed). Both nozzle styles/products were pressed at about 7,653 PSI. The 75-15-10 BP (these latest tests wtih ERC (eastern red cedar) bedding) is working well in an end-burner configuration. The nozzle opening (throat) is 1/8" which is 1/4 of the ID of the tube (tubes are 1/2", 25% of that is 0.125"). I'm adding 3% by weight H2O to the BP and pressing at around 3,000 PSI in a tube which has been wrapped with PVC tubing (split) and hose clamps to support the tube from distending/rupturing. Tooling is homebrew SS for an end-burner.

I think I'm going to have to build a "custom" rocket to use these motors as they are 5.5" long and slightly larger in OD than the Estes motors. So, there won't be any using these in the Estes rockets. That's gonna take a minute so it may be a bit before I can test these with model rockets. I also, now, will attempt to build core-burners as I think I'm gonna need the extra oomph to get any kind of heading worth messing with into the air. Now that I've succeeded at what I set out to do, I'm a lot more relaxed. Now this is fun. Thanks for the help and input, all.

The motor on the left is the PKL as an Estes-clone nozzle which was fired for a very short time. The one on the right was the "fancy" mix made up as a de Laval nozzle which flew to maybe 200' and then popped a parachute release charge.

--HC

March 12, 2020

Using that stuff for threadlocking sounds a bit extreme....for the life of me I can not see how the device could be removed from barrel once this stuff sets. One might just as well weld it in place. You are right about the fire reactance, it does not break down of soften even at extreme temperatures. In fact it is used to fireproof wooden constructions....impregnation with waterglass shall render wood nonflammable. Even to the extent where it does not burn in a furnace. I remember a case when construction workers took old wooden beams from a church roof construction and repurposed them as firewood. Turns out the beams were impreganted with waterglass and would simply not burn

Dosing is simple, you use a syringe and figure out the correct volume to add to each size nozzle/motor. Make measuring cups for the clay granules to keep their amount constant too. After that it is just repeating the movements. The nozzle can be pressed in one go when using the waterglass/bentonite composite. No need to do it in several sections. Inevitably some does collect on tooling, but if you scrub it off with water after use then it shall not pose too much resistance to cleaning. Letting it set with the clay for a few days and then trying to clean the residue is hard work.

I'm unaware of anyone actually trying to *remove* the device after affixing it with "Rocksett". I am *told*, but do not know for *fact* that the Rocksett thread locker stuff is sodium silicate. All that is *if* memory serves me. I don't try to pass along misinformation and I try to fact-check my stuff, but I make mistakes from time to time. https://www.brownells.com/gunsmith-tools-supplies/general-gunsmith-tools/thread-locking-liquids/rocksett-prod54624.aspx

I read an interesting thing in part today where a guy "wrote the book" on making model rocket motors back in the 70's. I have not finished reading the piece, but it sounds like he was saying that, to wrap convolute motor tubes, to use sodium silicate as the adhesive instead of white glue. I may be screwing up a detail so don't quote me on that. I can tell you that trying to make my own convolute tubes with wood glue has been a fiasco (reduced or not reduced, didn't matter). I'm going to go back and read the rest of that page later. Maybe I should be trying sodium silicate to bond the layers of paper. IF that worked then maybe it would prevent the inside of the tube from burning and would allow for "reloads". Maybe.

To be sure I'm understanding correctly: just scoop the necessary amount of clay into the motor tube, squirt the amount of sodium silicate necessary (as determined by testing) on top of the loose clay in the motor tube, and press it all in one go? Is there a recommended PSI? I've not used the sodium silicate so this may be a silly question, having not handled the substance, but won't it squish up past the tooling? Or does it soak into the clay that fast? Since I was at the pottery shop, and since it's 40 minutes the wrong way for my drive from the house to the shop, I bought a bag of bentoninte "just to be sure". My current "solution" doesn't require bentonite so I have no need of it. Using your process would give me a use for it.

--HC

March 12, 2020

To be sure I'm understanding correctly: just scoop the necessary amount of clay into the motor tube, squirt the amount of sodium silicate necessary (as determined by testing) on top of the loose clay in the motor tube, and press it all in one go? Is there a recommended PSI? I've not used the sodium silicate so this may be a silly question, having not handled the substance, but won't it squish up past the tooling? Or does it soak into the clay that fast? Since I was at the pottery shop, and since it's 40 minutes the wrong way for my drive from the house to the shop, I bought a bag of bentoninte "just to be sure". My current "solution" doesn't require bentonite so I have no need of it. Using your process would give me a use for it.

--HC

Yep....scoop, squirt, press, be done in in go. I used bentonite kitty litter granules of the dirt cheap kind in combination with a diluted down waterglass solution and forgot about any nozzle related problems. I soaks right up into the granules and does not creep up to the tools when the correct amount is used. Surely some will collect on spindle and nozzle seat surface, but it is not really a problem if cleaned up after use. One does not need a monstrous force for pressing....just keep pushing until you sense it compacting to a state where little happens upon increasing the force. Ususally there is a clearcut moment when the granules compact to a state that leaves no more room for further movement. I have no clear recollection about the actual force I used for for pressing (it was several years ago if not close to a decade), but I can figure it out for a reference if that helps you.

March 12, 2020

Success-er!

I remade the tooling for the Estes-style nozzle today and pressed a PKL (plain kitty litter) nozzle. Looked AMAZING! Being me, I had to bung up a bit on the machining and it's kind of a pill to remove the motor/nozzle from the mandrel but it works. I got so excited that, while mixing the H2O and BP, I forgot to smash the second half of the charge into the cup I was messing with and then only packed that first bit into the motor (I thought I got it done quickly). Major Dumbass strikes again. I've been me for a while and that kind of junk happens all too often. Anyway, I did a burn test on it (having already put the clay bulkhead in the motor before realizing I was short on BP). It burned very shortly, of course, but it didn't blow out the nozzle or erode it any. I will have to try again and get a longer burn with my "standard" 15g of BP, but optimism is high.

I also pressed another of the hawthorn-grog-wax nozzles and loaded it with BP (15g) then 3g of "delay" mix (60-40 KNO3 to charcoal), then a clay bulkhead, then some fine (-70+100 BP) to fill the hole I drilled in the bulkhead and then some -30+50 BP to near the top and a 1/2 tsp (a little less, actually) light-packed clay plug. A "complete" model rocket motor, my very first. I'm so proud. I shot this one, too. OMG, same as yesterday: flash, whoosh, straight up right quick! Got to the top, slight delay (it seemed...kinda hard to tell...I think these things are hitting 200 feet) and a pretty good POP! I was able to recover this one, thank God. The nozzle looks really good, and the pop charge didn't blow the tube up. I'm not sure I'm really happy with the delay charge/time. I think I need to do some static burn tests on that. I may need a different formula/mix for the delay (I'm all ears if anyone has something better). I also need to find a tune on the pop charge. I heard the report from the ground which makes me think that the pop charge was too much and likely would have blown a rocket body tube open or sent the clay as shrapnel trough a plastic parachute.

The flame formation from the PKL Estes-style nozzle looked different than what I've seen from the de Laval-style nozzles I've shot, but until I can put this into a model with an altimeter, I'll not have any way to know if one nozzle gets better "efficiency" than another.

In summary: plain, non-scoopable, cheap kitty litter, when formed like an Estes-brand nozzle, worked well in a handicapped/limited test. Having a more complicated nozzle form (de Laval) required several iterations of mixes to end at 61% hawthorn fire clay, 31% grog, and 8% wax (heated and mixed). Both nozzle styles/products were pressed at about 7,653 PSI. The 75-15-10 BP (these latest tests wtih ERC (eastern red cedar) bedding) is working well in an end-burner configuration. The nozzle opening (throat) is 1/8" which is 1/4 of the ID of the tube (tubes are 1/2", 25% of that is 0.125"). I'm adding 3% by weight H2O to the BP and pressing at around 3,000 PSI in a tube which has been wrapped with PVC tubing (split) and hose clamps to support the tube from distending/rupturing. Tooling is homebrew SS for an end-burner.

I think I'm going to have to build a "custom" rocket to use these motors as they are 5.5" long and slightly larger in OD than the Estes motors. So, there won't be any using these in the Estes rockets. That's gonna take a minute so it may be a bit before I can test these with model rockets. I also, now, will attempt to build core-burners as I think I'm gonna need the extra oomph to get any kind of heading worth messing with into the air. Now that I've succeeded at what I set out to do, I'm a lot more relaxed. Now this is fun. Thanks for the help and input, all.

The motor on the left is the PKL as an Estes-clone nozzle which was fired for a very short time. The one on the right was the "fancy" mix made up as a de Laval nozzle which flew to maybe 200' and then popped a parachute release charge.

--HC

You should have no problem getting these into Estes rocket tubes. I fly homemade motors in commercial Estes/Quest rockets all the time--a hell of a lot cheaper than store bought motors, especially D/Es and larger, and you can customize them anyway you want. The length can be shortened by cutting off any dead space atop the ejection charge retainer, or you can just use paper endcaps atop your ejection charge in a pinch--glue em in with wood glue, and you'll get sufficient containment for decent ejection. Or you can just fill the whole damned tube with additional fuel and give it a short core (what i do, and Estes with their larger motors), but you'd need to dial it in again for your needs. If your motor's flying 200 feet, you probably have a B-performing motor when you streamline it with a nosecone and fins, that'll likely reach at least double that height (weight/friction dependent). With the larger motor though, you need to pay close attention to your CG/CP locations, and might need additional weight in the nose to prevent parabolic flight (or corkscrews, or worse....). A longer body tube and forward weight... Try a static flight (pointing upwards but locked in place) to assess your ejection charge load. I tend to blow mine rather on the forceful end, so just need to use a longer elastic connector to the cone, and assure sufficient flame protection (actually wrap your parachute loosely in flame-proof paper/other material). If you're using B/C diameter motors that are a little oversized vs the standard 18 mm outer diameter, then they'll be too big for a BT-20 motor (18 mm inner diameter for a friction fit with A/B/C), but will fit into a BT-50 tube easily (24.1 mm ID); you just either need to make a custom motor mount (easy) or wrap your motor in a few turns of masking tape to get a uniform friction fit (easier!). Or you could easily adapt the standard plastic ABC to D/E motor mount adapters to fit your tubes with a dremel. For standard body tube sizing, please visit: https://www.hobbylinc.com/rockets/info/rockets_tubesizes.htm.

I've reloaded commercial motor tubes (once, D & E sized) after cleaning them out, but hand ram, need tooling that protects the stock nozzle, and don't get the pressures that Estes does. Still, with a slightly elongated core, they will launch rockets. But I really don't bother with the 18mm motors. Most of my motors are based on 1-lb rocket tubing & tooling, so my motors are 3/4" ID/1" OD, stuffed to the gills with hot BP, 7.5" total length, with an inch core past the nozzle (coffee grinder milled bentonite only). Had nozzle erosion issues when I tried hand pounding bentonite granules into nozzles, but that disappeared when I switched to pre-ground litter/bentonite, hand rammed, too). Motors are somewhere in the F/G range, with regular flights well above 1000 feet estimated, pushing heavier than usual (for model rocketry) projectiles. And a badass hot long burn, made cooler by addition of spherical titanium (again, I hand ram, so no sponge titanium). They put out a 5-8 foot sparky flame that is gorgeous, and give a several second burn time. The initial coring helps speed up initial launchpad departure. You will absolutely cook any wimpy commercial Estes launcher with these motors, so you'll need to construct your own, with a 1/4" x 4 foot guide rod; i use steel though Al works ok too. Don't aim the blast deflector at yourself, please.

These motors are a tight fit inside a BT-50 but will fit BT-55s and 60s with a little modification. Or, you can roll your own body tubes with manila folder stock that are a little tougher than commercial tubes, to any specific inner diameter desired. My motor tubes are either convoluted pre-cut 1-lb tubes from Caleb or self-cut from Phil's spiral (still tough enough) 2-foot sections; they both work great. I haven't had a need to coat with sodium silicate, but would probably silicate-coat the inside walls it if I planned on reusing the tubes, to minimize likelihood of burnthrough. These motors get hot, and stay hot, so your rocket construction needs to consider this. Sure, the larger motors use a little more BP, but the performance difference is night-and-day vs recreating B motors--I suspect that if you try em out you will never go back (especially when B and C motors are $1.70 each in bulk packs (no tax and free shipping over $100 from hobbylinc).

Nice experimenting you've been doing. Good job. And have fun!!

March 13, 2020

Yep....scoop, squirt, press, be done in in go. I used bentonite kitty litter granules of the dirt cheap kind in combination with a diluted down waterglass solution and forgot about any nozzle related problems. I soaks right up into the granules and does not creep up to the tools when the correct amount is used. Surely some will collect on spindle and nozzle seat surface, but it is not really a problem if cleaned up after use. One does not need a monstrous force for pressing....just keep pushing until you sense it compacting to a state where little happens upon increasing the force. Ususally there is a clearcut moment when the granules compact to a state that leaves no more room for further movement. I have no clear recollection about the actual force I used for for pressing (it was several years ago if not close to a decade), but I can figure it out for a reference if that helps you.

Awesome, I'll try that, what the heck. I am going to get some sodium silicate, anyway, to try with the paper tubes. Buying 1/2" and 3/4" tubes isn't too bad except the one place I've been getting them from charges a fortune for shipping and another place seems to only have 3/4" tubes with 1/4" wall. If I could make them myself then larger would be doable. Not sure I'd ever do it but...I might try one. I understand what you're saying about the compaction kind of hitting a spot where compaction markedly stalls so I don't think there's a need for you to figure it out. Thank you, though.

I am left with a question, though: how much did you dilute the sodium silicate and with what did you dilute it?

--HC

March 13, 2020

You should have no problem getting these into Estes rocket tubes. I fly homemade motors in commercial Estes/Quest rockets all the time--a hell of a lot cheaper than store bought motors, especially D/Es and larger, and you can customize them anyway you want. The length can be shortened by cutting off any dead space atop the ejection charge retainer, or you can just use paper endcaps atop your ejection charge in a pinch--glue em in with wood glue, and you'll get sufficient containment for decent ejection. Or you can just fill the whole damned tube with additional fuel and give it a short core (what i do, and Estes with their larger motors), but you'd need to dial it in again for your needs. If your motor's flying 200 feet, you probably have a B-performing motor when you streamline it with a nosecone and fins, that'll likely reach at least double that height (weight/friction dependent). With the larger motor though, you need to pay close attention to your CG/CP locations, and might need additional weight in the nose to prevent parabolic flight (or corkscrews, or worse....). A longer body tube and forward weight... Try a static flight (pointing upwards but locked in place) to assess your ejection charge load. I tend to blow mine rather on the forceful end, so just need to use a longer elastic connector to the cone, and assure sufficient flame protection (actually wrap your parachute loosely in flame-proof paper/other material). If you're using B/C diameter motors that are a little oversized vs the standard 18 mm outer diameter, then they'll be too big for a BT-20 motor (18 mm inner diameter for a friction fit with A/B/C), but will fit into a BT-50 tube easily (24.1 mm ID); you just either need to make a custom motor mount (easy) or wrap your motor in a few turns of masking tape to get a uniform friction fit (easier!). Or you could easily adapt the standard plastic ABC to D/E motor mount adapters to fit your tubes with a dremel. For standard body tube sizing, please visit: https://www.hobbylinc.com/rockets/info/rockets_tubesizes.htm.

I've reloaded commercial motor tubes (once, D & E sized) after cleaning them out, but hand ram, need tooling that protects the stock nozzle, and don't get the pressures that Estes does. Still, with a slightly elongated core, they will launch rockets. But I really don't bother with the 18mm motors. Most of my motors are based on 1-lb rocket tubing & tooling, so my motors are 3/4" ID/1" OD, stuffed to the gills with hot BP, 7.5" total length, with an inch core past the nozzle (coffee grinder milled bentonite only). Had nozzle erosion issues when I tried hand pounding bentonite granules into nozzles, but that disappeared when I switched to pre-ground litter/bentonite, hand rammed, too). Motors are somewhere in the F/G range, with regular flights well above 1000 feet estimated, pushing heavier than usual (for model rocketry) projectiles. And a badass hot long burn, made cooler by addition of spherical titanium (again, I hand ram, so no sponge titanium). They put out a 5-8 foot sparky flame that is gorgeous, and give a several second burn time. The initial coring helps speed up initial launchpad departure. You will absolutely cook any wimpy commercial Estes launcher with these motors, so you'll need to construct your own, with a 1/4" x 4 foot guide rod; i use steel though Al works ok too. Don't aim the blast deflector at yourself, please.

These motors are a tight fit inside a BT-50 but will fit BT-55s and 60s with a little modification. Or, you can roll your own body tubes with manila folder stock that are a little tougher than commercial tubes, to any specific inner diameter desired. My motor tubes are either convoluted pre-cut 1-lb tubes from Caleb or self-cut from Phil's spiral (still tough enough) 2-foot sections; they both work great. I haven't had a need to coat with sodium silicate, but would probably silicate-coat the inside walls it if I planned on reusing the tubes, to minimize likelihood of burnthrough. These motors get hot, and stay hot, so your rocket construction needs to consider this. Sure, the larger motors use a little more BP, but the performance difference is night-and-day vs recreating B motors--I suspect that if you try em out you will never go back (especially when B and C motors are $1.70 each in bulk packs (no tax and free shipping over $100 from hobbylinc).

Nice experimenting you've been doing. Good job. And have fun!!

Thanks for the reply. Some good stuff here.

After reading what you wrote, I double checked the fitment of my motors versus the Estes motors (and used dial calipers to check the diameter) and the diameter is virtually identical. The problem was that some of my motors casings are either swollen or smashed a bit and do not fit. That's just a booboo on my part, I should have tested one that looked perfect.

CG = Center of Gravity, check. What's the CP? I will probably feel like an idiot, but at this moment, "CP" isn't ringing a bell. You're saying that adding weight to the nose cone (moving the CG forward) will reduce parabolic flight (or other flight problems)? I'm a tinkerer and the BP and motors have been fun but I've never done anything with rockets except Estes models and I built them per the instructions; I don't know or have experience as a "rocket scientist". Cool idea on wrapping the parachute, I'd not thought of that. Possibly reduce the amount of force to eject it, too. Thanks for that link, the info is useful and then I clicked on a product link and it seems they've got all the stuff I might need to build a rocket model from scratch. I'd not yet done any searching for where to get the parts. I don't have to search now.

When I get all the basics nailed then I'll look at adding stuff to the fuel. It'd be cool to have a spark trail, particularly on a core-burner lifting a heading for night. But I've got a bit to go before I start trying to make stars. I found out firsthand about adding a little core to boost it off the launch pad faster. Wow, it helps. I did have too much core, though, through a couple of tests (documented in this thread somewhere back), and blew the fuel grain and bulkhead out of a couple of motors. Got it on the homemade launcher. That'll be no problem. I have done metal fabrication as a hobby/business for quite a few years now. I have a plasma table. And Inventor. I got this.

I have 25 tubes 3/4" diameter. I've not even made tooling for them yet. I figured I'd start on the small stuff and figure it out. I just got another 50 of the 1/2" tubes (5.5" long), and still have maybe 10 of them from my first batch of 25, maybe I have a few more. I'll build a model rocket from scratch (sort of...from parts from places like HobbyLinc) and get some successes there. Then I'll do some 3/4" stuff and see how that goes. I'd like to make some multi-stage motors, too. I never had a multi-stage rocket before.

Thank you. I like the detail stuff, it's been a lot of fun. Even the worst motor I've tried making this go around (since I started in again trying to build motors as adult) still moved upwards. Can't say the same for the stuff I was trying as a kid.

It sounds like you do a fair amount of this work which makes me wonder: why don't you have a hydraulic press for doing this work? I don't remember what I paid for it, but my Horrible Freight press couldn't have been that much (bought it many years ago). There are some fairly easy instructions/ideas on Skylighter for how to make a hydraulic short-stroke ram into a force indicator (with the addition of a hydraulic pressure gauge). Not busting your chops, just curious.

--HC

March 13, 2020

I am left with a question, though: how much did you dilute the sodium silicate and with what did you dilute it?

--HC

Tap water does the trick. As for dilution ratio....it is not really critical, but if I recall correctly I took equal volumes of the thick silicate syrup and regular tap water. That yielded a solution which was quite liquid and seeped into the clay granules very swiftly. To be honest I can not recall what concentration the undiluted waterglass solution had, but it was concentrated for sure.

March 13, 2020

Thanks for the reply. Some good stuff here.

After reading what you wrote, I double checked the fitment of my motors versus the Estes motors (and used dial calipers to check the diameter) and the diameter is virtually identical. The problem was that some of my motors casings are either swollen or smashed a bit and do not fit. That's just a booboo on my part, I should have tested one that looked perfect.

CG = Center of Gravity, check. What's the CP? I will probably feel like an idiot, but at this moment, "CP" isn't ringing a bell. You're saying that adding weight to the nose cone (moving the CG forward) will reduce parabolic flight (or other flight problems)? I'm a tinkerer and the BP and motors have been fun but I've never done anything with rockets except Estes models and I built them per the instructions; I don't know or have experience as a "rocket scientist". Cool idea on wrapping the parachute, I'd not thought of that. Possibly reduce the amount of force to eject it, too. Thanks for that link, the info is useful and then I clicked on a product link and it seems they've got all the stuff I might need to build a rocket model from scratch. I'd not yet done any searching for where to get the parts. I don't have to search now.

When I get all the basics nailed then I'll look at adding stuff to the fuel. It'd be cool to have a spark trail, particularly on a core-burner lifting a heading for night. But I've got a bit to go before I start trying to make stars. I found out firsthand about adding a little core to boost it off the launch pad faster. Wow, it helps. I did have too much core, though, through a couple of tests (documented in this thread somewhere back), and blew the fuel grain and bulkhead out of a couple of motors. Got it on the homemade launcher. That'll be no problem. I have done metal fabrication as a hobby/business for quite a few years now. I have a plasma table. And Inventor. I got this.

I have 25 tubes 3/4" diameter. I've not even made tooling for them yet. I figured I'd start on the small stuff and figure it out. I just got another 50 of the 1/2" tubes (5.5" long), and still have maybe 10 of them from my first batch of 25, maybe I have a few more. I'll build a model rocket from scratch (sort of...from parts from places like HobbyLinc) and get some successes there. Then I'll do some 3/4" stuff and see how that goes. I'd like to make some multi-stage motors, too. I never had a multi-stage rocket before.

Thank you. I like the detail stuff, it's been a lot of fun. Even the worst motor I've tried making this go around (since I started in again trying to build motors as adult) still moved upwards. Can't say the same for the stuff I was trying as a kid.

It sounds like you do a fair amount of this work which makes me wonder: why don't you have a hydraulic press for doing this work? I don't remember what I paid for it, but my Horrible Freight press couldn't have been that much (bought it many years ago). There are some fairly easy instructions/ideas on Skylighter for how to make a hydraulic short-stroke ram into a force indicator (with the addition of a hydraulic pressure gauge). Not busting your chops, just curious.

--HC

Your dial calipers will get a lotta use, especially if you start fitting to body tubes. "CP" is Center of Pressure, a common term in rocketry, from models to NASA rockets. A decent link that details it can be found here: http://www.rockets4schools.org/images/Basic.Rocket.Stability.pdf . Clearly you know what the CG is. The CP is the point where the rocket would rotate about (similar to CG) due to a lateral wind force. For example, with huge fins, the CP balance point would be moved south towards the motor. You want to keep your CP behind your CG, and you want at least 1 body-tube diameter separating the two, at minimum; this is called "1-caliber stability" and most model rockets are tuned in this neighborhood. It is also possible to make a rocket "too" stable. The CP/CG relationship will change during flight--the CG will move forward as fuel burns off; the CP is innate to the rocket and never changes (unless you change fins, rocket length, or body tube diameter).

Model rocket prices are exorbitant for a few cents worth of cardboard tubes, plastic or balsa nose cones, and tiny cardboard retainer rings, etc.... There are several ways to mitigate this. One is to make all parts yourself. You can make serviceable fins from plastic sheeting. Body tubes can be rolled manila folders, kraft paper... Motor mounts, retaining rings can be rolled to custom size and cut to length. Shock cord is cheap elastic, of any width desired, from the craft stores. If cloth covered instead of bare rubber, then consider soaking it in concentrated sodium bicarbonate/baking soda solution to provide some flame protection. Make your own ejection wadding with bicarb-saturated paper towels or tissues (robbery buying commercial). For smaller diameter rockets, can use cellulose insulation (big bag for cheap at HD) that is all that commercial Dog Vomit is. All for pennies. A mylar space blanket will make all the parachutes you'll need. The 2" wide crepe rolls of paper from the Dollar Store party section make excellent streamers and are already fire-retardant (need to be for hanging decorations); haven't tried, but they might make cheap ejection wadding. Another alternative is to get the Estes Designer kit, which allows you to make up to 8 custom rockets; it's kinda pricey unless you find it on sale (currently $68 at Hobbylinc), but has everything you'd need for some cool builds. Start crude so you don't lament if a CATO shreds a rocket (body tube at least). There are many cheap small kits for your B motors, especially if bought in bulk (Wizards, Vikings, etc...). The ready-to-fly ones can be cheap enough, but you'd likely have to modify the motor mount to accommodate your longer motors (or just let them hang out the back of the rocket). I'd go the pre-built cheapos for initial tests, and probably move over to cheaper (but easily high quality) home-made parts for testing new/larger motors. Your motors can be dual use for launching/retrieving rockets, or for lifting shells (though most, but not all, use full coreburner motors for that).

Excellent that you have a stockpile of tubes, and yes, shipping can get expensive, particularly on smallish orders. I can and have reused 3/4" tubes (and commercial D/E motors) after thorough cleaning and inspection, with good results. Obviously the potential for a failure is increased with anything but a pristine new tube, but you'll be surprised what you can get away with.

Multistage is another beast with homemade motors. Though I haven't attempted it myself, I can see no reason why you could not use your primary motor to ignite a second motor instead of a time fuse on a header! It's all passing fire, just to a different recipient. Shouldn't be an issue, and I'm sure you could sent your rockets stratospheric.

If you haven't read Ned Gorski's Skylighter article on recreating and flying Estes D/E motors, then it's worth a read: https://www.skylighter.com/blogs/how-to-make-fireworks/how-to-make-estes-model-rocket-engines

I'm at HF at least twice/month, sometimes more frequently, and am familiar with their presses, and the well-documented modification tutorials and schematics. Though I use whistle for some enhanced shell breaks, and would love to press some whistle/strobe rockets sometime, it hasn't really been a priority. I actually enjoy pounding out my motors--it's cathartic and relaxing--and I get good consistency and results. And it's just as fast, I'd imagine, as loading increments, pressurizing, waiting for a given dwell time, depressurizing, loading next increment... with a press. Mandatory for safety with whistle and strobe, but not critical for most of my current projects where shell lift and rocket fuels are all BP based. Very likely I will acquire one sometime in the future, because whistle is definitely on my mind. Strobes, too. I'm planning a very busy springtime project list, particularly with the pending COVID-19-associated restrictions that are invariably coming soon (I'm a medical research scientist, doctorate...).

Anyways, hope some of this proves to be of use to you. Will look forward to hearing (seeing--video please) some of your upcoming designs!!

March 14, 2020

I'm unaware of anyone actually trying to *remove* the device after affixing it with "Rocksett". I am *told*, but do not know for *fact* that the Rocksett thread locker stuff is sodium silicate. All that is *if* memory serves me. I don't try to pass along misinformation and I try to fact-check my stuff, but I make mistakes from time to time. https://www.brownells.com/gunsmith-tools-supplies/general-gunsmith-tools/thread-locking-liquids/rocksett-prod54624.aspx

I read an interesting thing in part today where a guy "wrote the book" on making model rocket motors back in the 70's. I have not finished reading the piece, but it sounds like he was saying that, to wrap convolute motor tubes, to use sodium silicate as the adhesive instead of white glue. I may be screwing up a detail so don't quote me on that. I can tell you that trying to make my own convolute tubes with wood glue has been a fiasco (reduced or not reduced, didn't matter). I'm going to go back and read the rest of that page later. Maybe I should be trying sodium silicate to bond the layers of paper. IF that worked then maybe it would prevent the inside of the tube from burning and would allow for "reloads". Maybe.

To be sure I'm understanding correctly: just scoop the necessary amount of clay into the motor tube, squirt the amount of sodium silicate necessary (as determined by testing) on top of the loose clay in the motor tube, and press it all in one go? Is there a recommended PSI? I've not used the sodium silicate so this may be a silly question, having not handled the substance, but won't it squish up past the tooling? Or does it soak into the clay that fast? Since I was at the pottery shop, and since it's 40 minutes the wrong way for my drive from the house to the shop, I bought a bag of bentoninte "just to be sure". My current "solution" doesn't require bentonite so I have no need of it. Using your process would give me a use for it.

--HC

If you decide to give rolling your own tubes a go I'd recommend playing around with dextrin glue rather than the sodium silicate. I messed around with this a bit before I just bought a bunch of tubes from Woodys. Not sure where you are buying tubes but I'd check them out if you haven't. Caleb is the man.

I never tried rolling with silicate but what I saw from guys that were building their own tube rolling machines and experimenting far more extensively than me with glues, the silicate actually dries too hard and makes for a brittle tube. Wood glue works well but is hard to work with unless you thin it out with water and all that extra moisture can lead to shrinkage issues. Ideally you want the tube to come off the mandrel dimensionally stable. Dextrin or starch based glues are pretty much the standard in the paper product industry. You can get a glue with high solids content that still has a workable viscosity and good balance of slip and tack, and they are easy to tune to specific applications. Dextrin is also a hell of a lot cheaper and easier to clean up. Let me know if you start messing with this and I can send you links to some threads/website with lots of info on dextrin adhesives and tube rolling.

March 14, 2020

Tap water does the trick. As for dilution ratio....it is not really critical, but if I recall correctly I took equal volumes of the thick silicate syrup and regular tap water. That yielded a solution which was quite liquid and seeped into the clay granules very swiftly. To be honest I can not recall what concentration the undiluted waterglass solution had, but it was concentrated for sure.

Okay, thanks on the dilution. I have a gallon of the stuff as "concrete" or "floor" sealer which should be here tomorrow. I'll try making a nozzle with it maybe on Monday when I get to the shop. I'll try a motor tube tomorrow, though, when it gets here (my nozzle stuff is 30 miles away at a different property).

--HC

March 14, 2020

Your dial calipers will get a lotta use, especially if you start fitting to body tubes. "CP" is Center of Pressure, a common term in rocketry, from models to NASA rockets. A decent link that details it can be found here: http://www.rockets4schools.org/images/Basic.Rocket.Stability.pdf . Clearly you know what the CG is. The CP is the point where the rocket would rotate about (similar to CG) due to a lateral wind force. For example, with huge fins, the CP balance point would be moved south towards the motor. You want to keep your CP behind your CG, and you want at least 1 body-tube diameter separating the two, at minimum; this is called "1-caliber stability" and most model rockets are tuned in this neighborhood. It is also possible to make a rocket "too" stable. The CP/CG relationship will change during flight--the CG will move forward as fuel burns off; the CP is innate to the rocket and never changes (unless you change fins, rocket length, or body tube diameter).

Model rocket prices are exorbitant for a few cents worth of cardboard tubes, plastic or balsa nose cones, and tiny cardboard retainer rings, etc.... There are several ways to mitigate this. One is to make all parts yourself. You can make serviceable fins from plastic sheeting. Body tubes can be rolled manila folders, kraft paper... Motor mounts, retaining rings can be rolled to custom size and cut to length. Shock cord is cheap elastic, of any width desired, from the craft stores. If cloth covered instead of bare rubber, then consider soaking it in concentrated sodium bicarbonate/baking soda solution to provide some flame protection. Make your own ejection wadding with bicarb-saturated paper towels or tissues (robbery buying commercial). For smaller diameter rockets, can use cellulose insulation (big bag for cheap at HD) that is all that commercial Dog Vomit is. All for pennies. A mylar space blanket will make all the parachutes you'll need. The 2" wide crepe rolls of paper from the Dollar Store party section make excellent streamers and are already fire-retardant (need to be for hanging decorations); haven't tried, but they might make cheap ejection wadding. Another alternative is to get the Estes Designer kit, which allows you to make up to 8 custom rockets; it's kinda pricey unless you find it on sale (currently $68 at Hobbylinc), but has everything you'd need for some cool builds. Start crude so you don't lament if a CATO shreds a rocket (body tube at least). There are many cheap small kits for your B motors, especially if bought in bulk (Wizards, Vikings, etc...). The ready-to-fly ones can be cheap enough, but you'd likely have to modify the motor mount to accommodate your longer motors (or just let them hang out the back of the rocket). I'd go the pre-built cheapos for initial tests, and probably move over to cheaper (but easily high quality) home-made parts for testing new/larger motors. Your motors can be dual use for launching/retrieving rockets, or for lifting shells (though most, but not all, use full coreburner motors for that).

Excellent that you have a stockpile of tubes, and yes, shipping can get expensive, particularly on smallish orders. I can and have reused 3/4" tubes (and commercial D/E motors) after thorough cleaning and inspection, with good results. Obviously the potential for a failure is increased with anything but a pristine new tube, but you'll be surprised what you can get away with.

Multistage is another beast with homemade motors. Though I haven't attempted it myself, I can see no reason why you could not use your primary motor to ignite a second motor instead of a time fuse on a header! It's all passing fire, just to a different recipient. Shouldn't be an issue, and I'm sure you could sent your rockets stratospheric.

If you haven't read Ned Gorski's Skylighter article on recreating and flying Estes D/E motors, then it's worth a read: https://www.skylighter.com/blogs/how-to-make-fireworks/how-to-make-estes-model-rocket-engines

I'm at HF at least twice/month, sometimes more frequently, and am familiar with their presses, and the well-documented modification tutorials and schematics. Though I use whistle for some enhanced shell breaks, and would love to press some whistle/strobe rockets sometime, it hasn't really been a priority. I actually enjoy pounding out my motors--it's cathartic and relaxing--and I get good consistency and results. And it's just as fast, I'd imagine, as loading increments, pressurizing, waiting for a given dwell time, depressurizing, loading next increment... with a press. Mandatory for safety with whistle and strobe, but not critical for most of my current projects where shell lift and rocket fuels are all BP based. Very likely I will acquire one sometime in the future, because whistle is definitely on my mind. Strobes, too. I'm planning a very busy springtime project list, particularly with the pending COVID-19-associated restrictions that are invariably coming soon (I'm a medical research scientist, doctorate...).

Anyways, hope some of this proves to be of use to you. Will look forward to hearing (seeing--video please) some of your upcoming designs!!

I'm the kind of guy who carries dial calipers in his trucks "just because". I really do. Okay, I understand about the CP but I've got that article opened up and will read through it later.

I like the information "home brewing" the rockets but there's too much there to address it piece by piece to acknowledge it: suffice it to say; I read it and I appreciate it. From that, it makes me wonder if I could make my own spiral-wound body tubes with some kraft paper roll and glue. That'd be cool. I ordered 3 cheap Estes kits yesterday (all the same...just in case) and I'm trying to make my own motor mount tube. The file folder idea is gonna get tried. Convolute, thin kraft paper with Minwax Wood Hardener isn't working worth spit. I'm going to make an oversize motor mount to accommodate my longer motors. With the info you've mentioned, I'll check the CG and have to guess at CP.

On the reusing of tubes, I wonder if a light run through with a small Dremel wheel brush might clean the inside up well enough to keep minor defects from occurring around the fuel grain-motor tube area. Waxing the inside of the tube (after cleaning it) might help, too. However, I've not tried waxing a tube and I'm not sure how to go about that (I need to look that up before I suggest it I suppose).

I'm talking out of my butt here but....it would seem that multi-stage would be fairly easy as I'm thinking of putting a short length of "quick" visco fuse in the passifre on the lift stage which is inserted into the nozzle of the second/next stage. The "quick" stuff burns at 0.1-0.5 seconds per foot. That's pretty quick. Just make one motor with nothing but BP fuel and a passfire in the bulkhead, then the second stage would have the fuel and delay and ejection charge.

Yes, I've read that article before. I should go back and read it again since it's been a little while. I don't absorb everything on the first pass for sure.

I'm no expert so take all this with a grain of salt: I like the press because it gives me the ability to be repeatable. When I press the fuel, I let the pressure go above the target pressure a little bit because it does "bleed" down. I find a balance where the pressure holds long enough (I think) at the target pressure and move on. Each increment is pretty close in pressure to the others. I like knowing that my nozzle mix has been pressed consistently. I don't know that the fuel pressure really matters that much, but, again, I'm no expert and I could be very wrong. To my limited experience, the fuel doesn't seem to burn differently whether I press it at 3k PSI or a little more or a little less. So long as I don't leave voids in it, it seems to work well. I've read that BP burns faster under greater pressure but I've not seen that information from a source which I would call "authoritative". Smokeless powder is progressive for sure, but I'm not sure about the BP, and, if it is pressure-sensitive, it's not as sensitive as smokeless powder for sure. No real answers there, just thoughts.

I would like to start some basic stars to build for aerial displays. I'd love to build some mortars. I need to find some "simple" star comps to try. However, stars usually seem to contain some esoteric substances and some of these chemicals are dangerous. I don't want to hurt myself messing with something I missed a warning about (e.g. don't mill flash powder). I'm not sure I want to mess with whistle fuel...I have read it's sensitive (specifically, as you suggest, don't bang on it).

I was supposed to be in MA today with my son visiting my mother but we blew off the trip at the last minute because of the virus. Hope you stay safe.

Thank you, very helpful. I'll take a video of one of the modified Estes rockets and post it. It'll be mid-week at best.

--HC

March 14, 2020

If you decide to give rolling your own tubes a go I'd recommend playing around with dextrin glue rather than the sodium silicate. I messed around with this a bit before I just bought a bunch of tubes from Woodys. Not sure where you are buying tubes but I'd check them out if you haven't. Caleb is the man.

I never tried rolling with silicate but what I saw from guys that were building their own tube rolling machines and experimenting far more extensively than me with glues, the silicate actually dries too hard and makes for a brittle tube. Wood glue works well but is hard to work with unless you thin it out with water and all that extra moisture can lead to shrinkage issues. Ideally you want the tube to come off the mandrel dimensionally stable. Dextrin or starch based glues are pretty much the standard in the paper product industry. You can get a glue with high solids content that still has a workable viscosity and good balance of slip and tack, and they are easy to tune to specific applications. Dextrin is also a hell of a lot cheaper and easier to clean up. Let me know if you start messing with this and I can send you links to some threads/website with lots of info on dextrin adhesives and tube rolling.

Long story short: I have a fair amount of dextrin I made to add to BP which I will not add to BP. I could use it for this.

I have tried wood glue thinned with water and it doesn't work well. The paper absorbs the moisture and wrinkles badly. If you don't thin it then it leaves too much glue in the tube and it's soft and squishy. It has not worked well for me.

Yes, please, I'd like links to information on rolling tubes.

Thank you.

--HC

March 15, 2020

I'm the kind of guy who carries dial calipers in his trucks "just because". I really do. Okay, I understand about the CP but I've got that article opened up and will read through it later.

I like the information "home brewing" the rockets but there's too much there to address it piece by piece to acknowledge it: suffice it to say; I read it and I appreciate it. From that, it makes me wonder if I could make my own spiral-wound body tubes with some kraft paper roll and glue. That'd be cool. I ordered 3 cheap Estes kits yesterday (all the same...just in case) and I'm trying to make my own motor mount tube. The file folder idea is gonna get tried. Convolute, thin kraft paper with Minwax Wood Hardener isn't working worth spit. I'm going to make an oversize motor mount to accommodate my longer motors. With the info you've mentioned, I'll check the CG and have to guess at CP.

On the reusing of tubes, I wonder if a light run through with a small Dremel wheel brush might clean the inside up well enough to keep minor defects from occurring around the fuel grain-motor tube area. Waxing the inside of the tube (after cleaning it) might help, too. However, I've not tried waxing a tube and I'm not sure how to go about that (I need to look that up before I suggest it I suppose).

I'm talking out of my butt here but....it would seem that multi-stage would be fairly easy as I'm thinking of putting a short length of "quick" visco fuse in the passifre on the lift stage which is inserted into the nozzle of the second/next stage. The "quick" stuff burns at 0.1-0.5 seconds per foot. That's pretty quick. Just make one motor with nothing but BP fuel and a passfire in the bulkhead, then the second stage would have the fuel and delay and ejection charge.

Yes, I've read that article before. I should go back and read it again since it's been a little while. I don't absorb everything on the first pass for sure.

I'm no expert so take all this with a grain of salt: I like the press because it gives me the ability to be repeatable. When I press the fuel, I let the pressure go above the target pressure a little bit because it does "bleed" down. I find a balance where the pressure holds long enough (I think) at the target pressure and move on. Each increment is pretty close in pressure to the others. I like knowing that my nozzle mix has been pressed consistently. I don't know that the fuel pressure really matters that much, but, again, I'm no expert and I could be very wrong. To my limited experience, the fuel doesn't seem to burn differently whether I press it at 3k PSI or a little more or a little less. So long as I don't leave voids in it, it seems to work well. I've read that BP burns faster under greater pressure but I've not seen that information from a source which I would call "authoritative". Smokeless powder is progressive for sure, but I'm not sure about the BP, and, if it is pressure-sensitive, it's not as sensitive as smokeless powder for sure. No real answers there, just thoughts.

I would like to start some basic stars to build for aerial displays. I'd love to build some mortars. I need to find some "simple" star comps to try. However, stars usually seem to contain some esoteric substances and some of these chemicals are dangerous. I don't want to hurt myself messing with something I missed a warning about (e.g. don't mill flash powder). I'm not sure I want to mess with whistle fuel...I have read it's sensitive (specifically, as you suggest, don't bang on it).

I was supposed to be in MA today with my son visiting my mother but we blew off the trip at the last minute because of the virus. Hope you stay safe.

Thank you, very helpful. I'll take a video of one of the modified Estes rockets and post it. It'll be mid-week at best.

--HC

What rockets did you order? I ask because sometimes I repurpose rockets that are not "expected" to return home. So...I know about most of them. Intimately. Including CPs, which are simple to estimate, and essential if you are sending off loads of pyro instead of a delicate parachute! Common courtesy :+}

Rolling your own tubes? I've rolled a lot of body tubes for rockets (simple once you get your glue/former correct), but have never (yet) rolled a motor tube. Plenty of gerb tubes from Kraft paper that I'd expect might perform ok as motors, but never explicitly for that reason. Caleb's convoluted tubes are great! And so are Phil's spiral tubes at ihaveadotcom.com (hilarious); they're just as good and burn-through resistant. If you perfect the fine art of motor tube rolling then you'll save a lot of loot in the long run. This I am not expert on, but intend to learn, just for the DIY factor. Enjoy no matter what you pack your powder into. Rocket body tubes though? You'll soon tire of paying Estes prices, and can do it yourself, and better, for 1/10th the cost (not including time/labor, but this is a hobby).

For tube refurbishment for a second go, yes, a Dremel is great...I scrape any chunks crudely with a butter knife and then smooth (actually roughen) things out with a mini dremel sander, as far as I can reach (not very in small-diameter tubes). And smaller half-moon files are useful. Get it as close to a new interior as possible--even a little chunk of scrap on the wall might serve as a fracture nucleus for your fuel grain, or a pass-through for fire, both of which can cause CATOs. Waxing? Dunno. Never bothered. Plenty of info/how-to videos available. But I have painted my tubes with a diluted sodium silicate solution before for second uses, typically the last step before reloading, after filing out any leftover slag/goulash, which roughens up the walls a bit and might assist fuel pellet adherence/approximation and prevent potential flame blow-by issues along the wall. Never bothered waxing tubes. No need/no discernible benefit so far, at least with 1-pounders.

Multi-stage should be easy-peasy. It's just passing fire. Yes, fast visco should work. With both homemade and commercial motors, though, I'd up the odds a little and dip your visco into an NC/BP slurry on the external end to grab fire more certainly. in the nozzle/core of your secondary motor, I'd dab my fuse into NC lacquer (for sound attachment), and then fill any voids with hot BP to guarantee flame transfer and secondary motor ignition. Just like regular commercial rocket motors--it's just getting one to light another. Here, too, you can test this on the ground before you stuff it into a tube with fins! Easy stuff. Fun, too. I don't expect you'll have issues lighting one motor from another. Keep in mind, though, that you want less "ejection" and more "flame transfer"; the second motor firing will blow off the first booster, like an ejection charge.

Stars, many, are simple. Especially the BP based ones. Yes, there are many esoteric formulations out there, and as good pyros, we will continue to develop more. But star-making is not daunting, or expensive, even without a roller or pressing hardware! Cut stars are the simplest perhaps to begin playing with. You make a dough of comp like BP before granulating. Then roll it out flat to your desired thickness. Then either cut it into cubes with a drywall knife or similar or push it through a screen. There are many videos available. Usually helps to coat your sheet (top & bottom) with BP or your desired prime before cutting/pressing to 1) minimize sticking to knife or screen, and 2) pre-prime (likely will need more after). Not so challenging, and your first successful batches will be rewarding. Start out at 100-150 gram batches at first, to get you on track without using too many chems (if you screw up) and until you get your desired effect--then you can easily ramp up volumes for whatever you want to do. Simples! You can also "press" stars in cut-off plastic syringes or dedicated tooling of varying complexity/cost. These, too, I push by hand. Relaxing. You'll learn soon that burning a star on the ground doesn't typically show you how it will perform in flight. If it is not primed appropriately, a burst charge can inhibit star ignition (blowing blind). Colors and effects frequently look very different on a star in motion versus a star burning on a cinder block. So, you'll want a small mortar (cardboard is fine), or multiple dedicated small-diameter mortars of various sizes, to use as starguns to test out your stars/comets in motion. Easy stuff. The crudest way to evaluate your stars is to light one and just toss it in the air...

Mortars, too, are easy, and little ones are a great way to test out your stars ("starguns"). Shorter mortars are great fun for low aerial effects like mines, and a little longer (typically 6x inner diameter in length) for launching BP-lifted shells. I use HDPE exclusively, but you'll find your fiberglass lovers (lighter weight) and steel lovers (heavy, gotta bury them in the ground, though) for bigger shells than I worry about. HDPE blows great 2" shells or great 6" shells! Please do not use PVC tubing, even Schedule 80 "higher" pressure stuff; it is absolutely unsuitable for responsible pyro use, particularly as mortars or rocket tubes (though you will find many videos showing PVC motors--meh!).

Hey, you're going to have a lot of fun! It's refreshing that you are doing the appropriate research and asking before diving into a new project. Tips from others can often save you time and headaches, and occasionally save some skin on your butt.

And, as others have told me, you can roll your own tubes. I'm just too lazy...

Looking forward to your first video of your modified Estes; will be a hoot even if it CATOs.

Best of luck. As always, keep it (relatively) safe!!

March 15, 2020

Long story short: I have a fair amount of dextrin I made to add to BP which I will not add to BP. I could use it for this.

I have tried wood glue thinned with water and it doesn't work well. The paper absorbs the moisture and wrinkles badly. If you don't thin it then it leaves too much glue in the tube and it's soft and squishy. It has not worked well for me.

Yes, please, I'd like links to information on rolling tubes.

Thank you.

--HC

Ask and you shall receive. Sorry for the slightly spammy list of links. You'll find a mix of rolling techniques and glue experiments. I would pay attention to Col's posts--he know's what he is saying. A couple general comments: First, paper quality matters. Recycled kraft is hard to work with and not as strong, but you can still roll a decent tube with it. If you were getting wrinkles you probably were not rolling the tube tight enough. The key to good tubes is getting them rolled as tight as possible so there are no gaps between the layers of paper. To do this you want to roll with pressure on the mandrel and once the tube is rolled give it several more rolls in the same direction while pressing down hard. Some guys use a board for this to get more even pressure on the whole tube. Check out this video to get an old school idea of what I'm talking about. If getting them off the mandrel is hard (and it probably will be) I've found it's best to have a way to push rather than pull them off. This can be as simple as a board with a hole the same size as your mandrel.

For a totally different take you could try the poly-kraft technique Ned explains here. I've done this using freezer paper and it makes good tubes. The nice part about it is, since your dry wrapping it's easy to fix any telescoping and get things good and tight before baking. The down side is it's not very efficient unless you have several mandrels to bake a bunch at once, plus the cost of paper, bake time. I also am not one to recover my tubes and I don't like dumping plastic from the sky.

Ok, here's your homework:

https://www.borax.com/BoraxCorp/media/Borax-Main/Resources/Technical-Bulletin/borates-starch-dextrin-adhesives.pdf?ext=.pdf

http://pyrobin.com/files/starch%20and%20dextrin%20based%20adhesives%20-%20article.pdf

https://www.amateurpyro.com/forums/topic/7820-what-is-the-best-glue-for-cardboardpaper-tubes-rolling/

https://www.amateurpyro.com/forums/topic/9090-how-to-roll-pyro-tubes/

https://www.amateurpyro.com/forums/topic/10063-tube-roller-4oz-1-and-3-or-more/page-2

https://www.amateurpyro.com/forums/topic/11582-glue-for-hand-rolled-tubes/

https://www.amateurpyro.com/forums/topic/12431-wheat-paste-tubes-bake-them-to-harden/

March 19, 2020

What rockets did you order? I ask because sometimes I repurpose rockets that are not "expected" to return home. So...I know about most of them. Intimately. Including CPs, which are simple to estimate, and essential if you are sending off loads of pyro instead of a delicate parachute! Common courtesy :+}

Rolling your own tubes? I've rolled a lot of body tubes for rockets (simple once you get your glue/former correct), but have never (yet) rolled a motor tube. Plenty of gerb tubes from Kraft paper that I'd expect might perform ok as motors, but never explicitly for that reason. Caleb's convoluted tubes are great! And so are Phil's spiral tubes at ihaveadotcom.com (hilarious); they're just as good and burn-through resistant. If you perfect the fine art of motor tube rolling then you'll save a lot of loot in the long run. This I am not expert on, but intend to learn, just for the DIY factor. Enjoy no matter what you pack your powder into. Rocket body tubes though? You'll soon tire of paying Estes prices, and can do it yourself, and better, for 1/10th the cost (not including time/labor, but this is a hobby).

For tube refurbishment for a second go, yes, a Dremel is great...I scrape any chunks crudely with a butter knife and then smooth (actually roughen) things out with a mini dremel sander, as far as I can reach (not very in small-diameter tubes). And smaller half-moon files are useful. Get it as close to a new interior as possible--even a little chunk of scrap on the wall might serve as a fracture nucleus for your fuel grain, or a pass-through for fire, both of which can cause CATOs. Waxing? Dunno. Never bothered. Plenty of info/how-to videos available. But I have painted my tubes with a diluted sodium silicate solution before for second uses, typically the last step before reloading, after filing out any leftover slag/goulash, which roughens up the walls a bit and might assist fuel pellet adherence/approximation and prevent potential flame blow-by issues along the wall. Never bothered waxing tubes. No need/no discernible benefit so far, at least with 1-pounders.

Multi-stage should be easy-peasy. It's just passing fire. Yes, fast visco should work. With both homemade and commercial motors, though, I'd up the odds a little and dip your visco into an NC/BP slurry on the external end to grab fire more certainly. in the nozzle/core of your secondary motor, I'd dab my fuse into NC lacquer (for sound attachment), and then fill any voids with hot BP to guarantee flame transfer and secondary motor ignition. Just like regular commercial rocket motors--it's just getting one to light another. Here, too, you can test this on the ground before you stuff it into a tube with fins! Easy stuff. Fun, too. I don't expect you'll have issues lighting one motor from another. Keep in mind, though, that you want less "ejection" and more "flame transfer"; the second motor firing will blow off the first booster, like an ejection charge.

Stars, many, are simple. Especially the BP based ones. Yes, there are many esoteric formulations out there, and as good pyros, we will continue to develop more. But star-making is not daunting, or expensive, even without a roller or pressing hardware! Cut stars are the simplest perhaps to begin playing with. You make a dough of comp like BP before granulating. Then roll it out flat to your desired thickness. Then either cut it into cubes with a drywall knife or similar or push it through a screen. There are many videos available. Usually helps to coat your sheet (top & bottom) with BP or your desired prime before cutting/pressing to 1) minimize sticking to knife or screen, and 2) pre-prime (likely will need more after). Not so challenging, and your first successful batches will be rewarding. Start out at 100-150 gram batches at first, to get you on track without using too many chems (if you screw up) and until you get your desired effect--then you can easily ramp up volumes for whatever you want to do. Simples! You can also "press" stars in cut-off plastic syringes or dedicated tooling of varying complexity/cost. These, too, I push by hand. Relaxing. You'll learn soon that burning a star on the ground doesn't typically show you how it will perform in flight. If it is not primed appropriately, a burst charge can inhibit star ignition (blowing blind). Colors and effects frequently look very different on a star in motion versus a star burning on a cinder block. So, you'll want a small mortar (cardboard is fine), or multiple dedicated small-diameter mortars of various sizes, to use as starguns to test out your stars/comets in motion. Easy stuff. The crudest way to evaluate your stars is to light one and just toss it in the air...

Mortars, too, are easy, and little ones are a great way to test out your stars ("starguns"). Shorter mortars are great fun for low aerial effects like mines, and a little longer (typically 6x inner diameter in length) for launching BP-lifted shells. I use HDPE exclusively, but you'll find your fiberglass lovers (lighter weight) and steel lovers (heavy, gotta bury them in the ground, though) for bigger shells than I worry about. HDPE blows great 2" shells or great 6" shells! Please do not use PVC tubing, even Schedule 80 "higher" pressure stuff; it is absolutely unsuitable for responsible pyro use, particularly as mortars or rocket tubes (though you will find many videos showing PVC motors--meh!).

Hey, you're going to have a lot of fun! It's refreshing that you are doing the appropriate research and asking before diving into a new project. Tips from others can often save you time and headaches, and occasionally save some skin on your butt.

And, as others have told me, you can roll your own tubes. I'm just too lazy...

Looking forward to your first video of your modified Estes; will be a hoot even if it CATOs.

Best of luck. As always, keep it (relatively) safe!!

I got the Estes Patriot missile kit. I intend for these to come back but I will send them up on a home made motor. The motor tubes are 5" instead of the Estes 2.75" or so. If you know the CP that would be great, thank you. If not, I'll make a stab at it. I'm moving the CG for sure with the longer motor.

I've tried the motor tubes several times. And one body tube. The body tube I tried spiral and it didn't work out but it was once and I've got several sources of info to explore yet. The motor tubes...you know how when you go into a store and look for something for about 30 seconds and don't find it and ask an employee where it is? And they point/nod/look next to you or behind you or half an aisle down? You were soooo close, just not quite there. That's where I am on the motor tubes. Dextrin glue, currently with a little sodium silicate added to it, is working great. Something isn't quite right; the paper is too thin or the dextrin is too watery, I'm wearing the wrong purse for my outfit...something. But I'm close. I took some time to look up NEPT (New England Paper Tube). Interesting story and they're located in RI. Next time I get to MA to see my mother I'm going to make a trip there, if they offer tours. It's a neat story about their company and how they pulled back from the brink of failure by making paper tubes that no one else can/does in this country. I'm not trying to do the motor tubes to stick it to them, or even really to save the money (NEPT tubes are *good* and worth the $). But 1) I'd like to be able to "just 'cause", and 2) I'd like to be able to make larger motor tubes than what I see available from NEPT through the various suppliers that carry their stuff (1" is the largest I recall seeing (3# in the old nomenclature) although there may be a "6#", whatever size that is). I do need to look into the legalities...but it'd be cool to make a motor tube that was, say, 2" in diameter. I'll launch it from a platform I'll build to sit on the back of my pony.

Understood re tube refurb. I was making a test tube (test motor tube) from a previous test-fired motor yesterday and had to knock the nozzle out. I've knocked a few out that I've made in my present attempt with rockets. This one was one that was made with the 61% Hawthorne fire clay, 31% grog, 8% wax. It was hard as hell. It didn't want to come out. I tried penetrating it with a screwdriver and crushing the outside with a pair of pliers to fracture it. It came out, but it fought the whole way. FYI re the toughness of that mix for a nozzle. Maybe unnecessary, but worth knowing I suppose. Pressed kitty litter comes out easier.

Yes, I totally agree with priming the "input" end of the visco for ignition of an upper stage. I'd not thought of "gluing" the fuse into the upper stage with NC lacquer. That's a good idea. That's getting used. Understood re ejection of the previous stage.

I've been thinking in the box about stars, to an extent. I had not thought about it, but one could make smoke stars and shoot them in the daytime. I am pretty quick (sometimes) and saw a list of star names including "smoke stars" or something like that. Hmm, smoke bomb stuff (sugar/KNO3) melted and dipped into BP meal dust or very fine granules while liquid/gel/gooey would seem to make a primed smoke star. That clarity on the simplicity, and variety, of making stars is encouraging. I could be wrong, and that may not work, but at least it gets me motivated. The Tiger Tail star comp doesn't require anything fancy, I may try that for just, I assume, orange glow effect stars. I wonder about adding some coarse charcoal to a BP mix to make some orange ember tails. I need a shot of success, even if small. Understood re the roll out and cut with a "flour" of BP. I like the idea of a cut-off syringe as a star pump. Understood static vs dynamic testing of the stars. I like the idea of a baby mortar (star gun) for testing. That sounds like fun. Imma skip the "hold in hand, light star, toss".

I'm itching to do the mortars but I've not done any work on it yet. I have some 2-3/8" OD and 2-7/8" OD steel pipe. I have some 8" and I think I I have some 4", both on OD. Thinnest stuff I'll have is maybe 3/16" with most of it in the 0.250" or so range. I appreciate the warnings on the PVC. I was afraid of that stuff already. PVC will fracture if stressed properly whereas steel, mild steel anyway, is more prone to "rip and purge" with little if any shrapnel (maybe with high explosives it would make a lot of shrapnel, but not with BP I don't think). I have a strip of steel that's about a foot wide and 3 feet long and 1" thick. I can weld tubes to that and skip the burial. I'd love to try the HDPE (I've seen folks use the heavy, black poly pipe, which I'm assuming is HDPE) but I'm not sure where to source that locally. I would need something for the star guns. I don't have much in the small tubes of steel...I'll have to go dig through the stuff. There's a lot to this endeavor, it's going to take time. Hey, I like that metric: "6x ID". Thank you. Gives me a handle on where to start.

I'm grateful for the help. I don't want to get hurt doing this (or hurt my son or anyone else). There's some amazingly dangerous stuff you can make, sometimes accidentally, in this life. Best to try to learn a bit beforehand.

I got the motor mount tube rolled last night. I don't know if it'll work well or not, I'm about to try it out. Maybe finish the rocket tomorrow or the weekend. Amazon said Tuesday, then Thursday, and they showed up yesterday. I will shoot a video of it and post it when I get it in the air (or all over the place).

Thanks again.

--HC

Edited March 19, 2020 by hcb

March 19, 2020

The Patriot is cool. Kind of medium rate liftoff because it's a little chubby, shorter, and heavier than some--they're not meant to fly too high on ABC motors--definitely under 1000' tops. Probably half that on a C unless you're anal about finishing. But that's reasonably high in fireworking, and at least you can see the thing the whole time. Another "smoke" idea is to fill the parachute with a couple of teaspoons of talcum (baby) powder for a little extra puff at ejection.

Hopefully your motors will put out more total impulse than Estes C's. Would strongly suggest that you tape a stick to a motor or two and launch them like regular fireworks rockets before putting them inside your Patriot body. To make sure they don't CATO, have enough power to lift your rocket, and eject correctly. Might want to burn one upside down on a protected digital scale; you can calculate impulse from the reading and measured burn time, but you'll get a decent idea of their power from just launching skyward. Add a header, maybe your smoke comet or shell, for extra fun and to see what it can carry--if so, you'll want to pass fire, not have an ejection charge...

The heavier motor will move your CG back towards your CP. You can calculate your CG in 2 seconds once built (and with a motor in it), and estimate your CP pretty easily too, with a cardboard cutout of your rocket profile balanced on a stick. The Patriot is already kind of stocky, so the only way to adjust CP is to elongate with a longer body tube section (BT-60, I think) or enlarge the fins a little, but they probably come precut--you'd have to make your own. Might not matter all that much unless your CG/CP were super close. I'd be more concerned if my motors were really wimpy. Or you can add weight to the nosecone, whether permanently or temporarily/adjustable by drilling a pluggable hole in the (guessing plastic) cone and pouring in some sand or shot; epoxy w/sand for permanent. I'd do that last, after I know my motors were strong enough. You can increase launch stability by using a longer launch guide rod, to allow it to gather more speed before it's on its own (4 feet instead of usual 3 feet). Probably need a larger lug to accommodate a 1/4" rod, or 3/16" at minimum. Steel vs more bendy Al; less rod whip. The sissy little 1/8" aluminum launch rods from Estes are toys and not fit for anything useful except launching lil speedy baby rockets that get up to stable launch speed fast (disposable rockets, like their crappy weak launch rods).

1" x 6" cardboard tubes glued to any solid base with a fuse hole drilled make fine starguns for testing comps. Your steel is likely tough enough that no burying necessary--that's typically with larger mortars/shells where a CATO could be exceptionally dangerous. Never heard of anybody bothering to bury small-bore properly constructed steel starguns. Paper's cheap. Can buy them as tubes or premade from Cannonfuse.com and others or make your own, easily, in various diameters. You already have a couple of diameters of tubing; if it's tough enough for a rocket motor, it's more than tough enough for a mini mortar. Paint a little silicate solution around/in the fuse hole so they don't burn wide as quickly. Steel is more durable, but I use cardboard. Easier to drill. No rust. Toss em instead of clean em (or use for salutes/smoke). Zero worries about shrapnel. Easy. And you can get some pretty good height using smallish mines 1-2" for backyard fun when testing new comps. Even little tubes can be fun, especially if space/altitude is restricted (ya don't want to drive 20 miles to a launch site...). A couple of grams of lift, a little bag of stars, piece of fuse, cheap-ass mortar (can salvage tubes from commercial cakes, too)...bingo, stand back! Next thing you know, your mortars will become multi-tube cakes, oh my. Link em with QM or whatever speed visco you want. You'll never be as fast as the Chicom factories churning them out, but you can make any effect you want, and any size, for cheaper (labor doesn't count).

Edited March 19, 2020 by SharkWhisperer

March 21, 2020

Ask and you shall receive. Sorry for the slightly spammy list of links. You'll find a mix of rolling techniques and glue experiments. I would pay attention to Col's posts--he know's what he is saying. A couple general comments: First, paper quality matters. Recycled kraft is hard to work with and not as strong, but you can still roll a decent tube with it. If you were getting wrinkles you probably were not rolling the tube tight enough. The key to good tubes is getting them rolled as tight as possible so there are no gaps between the layers of paper. To do this you want to roll with pressure on the mandrel and once the tube is rolled give it several more rolls in the same direction while pressing down hard. Some guys use a board for this to get more even pressure on the whole tube. Check out this video to get an old school idea of what I'm talking about. If getting them off the mandrel is hard (and it probably will be) I've found it's best to have a way to push rather than pull them off. This can be as simple as a board with a hole the same size as your mandrel.

For a totally different take you could try the poly-kraft technique Ned explains here. I've done this using freezer paper and it makes good tubes. The nice part about it is, since your dry wrapping it's easy to fix any telescoping and get things good and tight before baking. The down side is it's not very efficient unless you have several mandrels to bake a bunch at once, plus the cost of paper, bake time. I also am not one to recover my tubes and I don't like dumping plastic from the sky.

Ok, here's your homework:
https://www.borax.com/BoraxCorp/media/Borax-Main/Resources/Technical-Bulletin/borates-starch-dextrin-adhesives.pdf?ext=.pdf
http://pyrobin.com/files/starch%20and%20dextrin%20based%20adhesives%20-%20article.pdf
https://www.amateurpyro.com/forums/topic/7820-what-is-the-best-glue-for-cardboardpaper-tubes-rolling/
https://www.amateurpyro.com/forums/topic/9090-how-to-roll-pyro-tubes/
https://www.amateurpyro.com/forums/topic/10063-tube-roller-4oz-1-and-3-or-more/page-2
https://www.amateurpyro.com/forums/topic/11582-glue-for-hand-rolled-tubes/
https://www.amateurpyro.com/forums/topic/12431-wheat-paste-tubes-bake-them-to-harden/

I try to come back and devote myself to complete replies in a timely fashion. I haven't had time to go through this thoroughly so I can't give a thorough and detailed response yet. But I don't want this to sit and look ignored. Thank you for the information, I will be going through this list. It will take me a while. I will come back when I'm done and make a proper reply.

Thank you.

--HC

March 23, 2020

I try to come back and devote myself to complete replies in a timely fashion. I haven't had time to go through this thoroughly so I can't give a thorough and detailed response yet. But I don't want this to sit and look ignored. Thank you for the information, I will be going through this list. It will take me a while. I will come back when I'm done and make a proper reply.

Thank you.

--HC

No worries, there's a lot to go through there. Let me know if you have any questions. I'm far from an expert, and I never went as far as building a machine for rolling, though I still toy with the idea. But I have had success making dextrin glues and played with a few different techniques for applying adhesive and hand rolling.

March 25, 2020

The Patriot is cool. Kind of medium rate liftoff because it's a little chubby, shorter, and heavier than some--they're not meant to fly too high on ABC motors--definitely under 1000' tops. Probably half that on a C unless you're anal about finishing. But that's reasonably high in fireworking, and at least you can see the thing the whole time. Another "smoke" idea is to fill the parachute with a couple of teaspoons of talcum (baby) powder for a little extra puff at ejection.

Hopefully your motors will put out more total impulse than Estes C's. Would strongly suggest that you tape a stick to a motor or two and launch them like regular fireworks rockets before putting them inside your Patriot body. To make sure they don't CATO, have enough power to lift your rocket, and eject correctly. Might want to burn one upside down on a protected digital scale; you can calculate impulse from the reading and measured burn time, but you'll get a decent idea of their power from just launching skyward. Add a header, maybe your smoke comet or shell, for extra fun and to see what it can carry--if so, you'll want to pass fire, not have an ejection charge...

The heavier motor will move your CG back towards your CP. You can calculate your CG in 2 seconds once built (and with a motor in it), and estimate your CP pretty easily too, with a cardboard cutout of your rocket profile balanced on a stick. The Patriot is already kind of stocky, so the only way to adjust CP is to elongate with a longer body tube section (BT-60, I think) or enlarge the fins a little, but they probably come precut--you'd have to make your own. Might not matter all that much unless your CG/CP were super close. I'd be more concerned if my motors were really wimpy. Or you can add weight to the nosecone, whether permanently or temporarily/adjustable by drilling a pluggable hole in the (guessing plastic) cone and pouring in some sand or shot; epoxy w/sand for permanent. I'd do that last, after I know my motors were strong enough. You can increase launch stability by using a longer launch guide rod, to allow it to gather more speed before it's on its own (4 feet instead of usual 3 feet). Probably need a larger lug to accommodate a 1/4" rod, or 3/16" at minimum. Steel vs more bendy Al; less rod whip. The sissy little 1/8" aluminum launch rods from Estes are toys and not fit for anything useful except launching lil speedy baby rockets that get up to stable launch speed fast (disposable rockets, like their crappy weak launch rods).

1" x 6" cardboard tubes glued to any solid base with a fuse hole drilled make fine starguns for testing comps. Your steel is likely tough enough that no burying necessary--that's typically with larger mortars/shells where a CATO could be exceptionally dangerous. Never heard of anybody bothering to bury small-bore properly constructed steel starguns. Paper's cheap. Can buy them as tubes or premade from Cannonfuse.com and others or make your own, easily, in various diameters. You already have a couple of diameters of tubing; if it's tough enough for a rocket motor, it's more than tough enough for a mini mortar. Paint a little silicate solution around/in the fuse hole so they don't burn wide as quickly. Steel is more durable, but I use cardboard. Easier to drill. No rust. Toss em instead of clean em (or use for salutes/smoke). Zero worries about shrapnel. Easy. And you can get some pretty good height using smallish mines 1-2" for backyard fun when testing new comps. Even little tubes can be fun, especially if space/altitude is restricted (ya don't want to drive 20 miles to a launch site...). A couple of grams of lift, a little bag of stars, piece of fuse, cheap-ass mortar (can salvage tubes from commercial cakes, too)...bingo, stand back! Next thing you know, your mortars will become multi-tube cakes, oh my. Link em with QM or whatever speed visco you want. You'll never be as fast as the Chicom factories churning them out, but you can make any effect you want, and any size, for cheaper (labor doesn't count)

The Patriot is cool. I checked the CG, easier than my prom date. The cut-out of the profile indicated the CP was way far forward. I modeled it pretty closely in OpenRocket and the CP was way farther back than the cut-out profile indicated. I shot it today. Either I got lucky or OpenRocket knows more than a cut-out profile indicates. Took off like a scalded ape. I didn't RTFM and didn't do something right with the AltimiterTwo (I set it to LAUNCH but I didn't wait for the READY to show and I guess it has to sit still and think about life for a minute or something) and didn't get data on the flight. It went up straight and high and deployed the parachute easily. Nothing blew up, nothing broke. I used a re-loaded Estes igniter (wire didn't break so I just coated it with some NC lacquer) and hit it with 12v from a cheap Amazon remote relay thing (not for rocketry, just a general remote relay). WHOOSH! I got a video of it but the video raw feed on the camera looks like I needed to zoom in a bunch and I couldn't track the rocket worth a darn. It was so fast and high right quick. I'll put the video together on the computer tomorrow over coffee.

On the chute opening, I got a puff of gray smoke...1/2 gram might be a bit much BP. I made notes but I think it was 1/2g of 20-30 mesh.

I think my rod is 4' now. The original Estes rod got bent (imagine that) and I replaced it with a brass brazing rod. I might be wrong on the length. It was plenty long for this rocket with this motor. I put a short core in my motor to give it a bit of a kick in the butt off the pad...it works.

On the CP thing...if I'd found it was lacking via the software, I was going to take some plasti-core sign material and rip a rib out of it and tape it on the bottom of the "factory" fins on the rocket. The material is light, free (bandit signs), and fairly rigid. I didn't want to have to add material/weight to the nose just because added weight lowers altitude/speed and I hate giving those things up. It was unnecessary. I decided to trust the OpenRocket model and, it seems, it was correct. Or beginners luck.

I'll try to attach a picture. I made a star gun yesterday with some stuff I had lying around. It's not supposed to be pretty, this stuff was literally laying on the floor in my shop. I just cut the stuff to length, dressed the top/mouth ends, drilled fuse holes, and welded to a base. Took me about 15 minutes, including the quick spin on the lathe to dress those mouths a bit. I made this with 3 tubes welded to a 4" x "that looks right" x 1/4" piece of steel flat bar. The three tubes are 3/8", 1/2", and 3/4" gas pipe. If you know anything about steel pipe/tubing, you know that those measurements (3/8", 1/2", 3/4") have *nothing* to do with the dimensions of the tubing (unless you cut a section to that length). I made them 6", 7", and 8" long, respectively. I made two test stars yesterday using some of my failed delay comp (roughly 50/50 KNO3/charcoal plus a little (6% maybe) sulfur). It's really close to a recipe for Tiger Tail star comp (or something like that). I made a couple about 1/2" diameter (rammed in a piece of 1/2" PEX tubing) after I added some -30 mesh (IIRC) charcoal flakes "just 'cause". I then primed them with some hot BP and dried them in the dehydrator. I loaded it all to bring home and try tonight. I shot one a bit ago. OMG! That's the coolest thing *ever*! Unreal! Beautiful! Burned out at apex, maybe 50' or so but I've got no way to know for sure.

Back to the star gun: I chose to use steel for this. I chose steel for a few reasons: 1) I have steel on hand, 2) I've been doing hobby and professional fabrication for 20+ years and have the tools and machines and the experience to make it and stick it, 3) a soft plug (star) sitting on an itty bitty bit (2-3 grams) of BP in a small-diameter steel tube doesn't scare me in the least. Now, if this was 6" and launching a 2-3# shell to 200'....I'd not be so cavalier.

I made some G1 Glitter Star something or another today (Skylighter article). It's basically BP components, some dextrin, and some Al powder, all of which I had so I did it. I didn't make any stars from it today...but you can bet your butt I'll be making some tomorrow!

Always, thanks for your time and help. I launched my first complete model rocket motor today and it worked flawlessly, and I couldn't have done it without the help I got from you and all the others who have helped me here.

--HC

March 25, 2020

The Patriot is cool. I checked the CG, easier than my prom date. The cut-out of the profile indicated the CP was way far forward. I modeled it pretty closely in OpenRocket and the CP was way farther back than the cut-out profile indicated. I shot it today. Either I got lucky or OpenRocket knows more than a cut-out profile indicates. Took off like a scalded ape. I didn't RTFM and didn't do something right with the AltimiterTwo (I set it to LAUNCH but I didn't wait for the READY to show and I guess it has to sit still and think about life for a minute or something) and didn't get data on the flight. It went up straight and high and deployed the parachute easily. Nothing blew up, nothing broke. I used a re-loaded Estes igniter (wire didn't break so I just coated it with some NC lacquer) and hit it with 12v from a cheap Amazon remote relay thing (not for rocketry, just a general remote relay). WHOOSH! I got a video of it but the video raw feed on the camera looks like I needed to zoom in a bunch and I couldn't track the rocket worth a darn. It was so fast and high right quick. I'll put the video together on the computer tomorrow over coffee.

On the chute opening, I got a puff of gray smoke...1/2 gram might be a bit much BP. I made notes but I think it was 1/2g of 20-30 mesh.

I think my rod is 4' now. The original Estes rod got bent (imagine that) and I replaced it with a brass brazing rod. I might be wrong on the length. It was plenty long for this rocket with this motor. I put a short core in my motor to give it a bit of a kick in the butt off the pad...it works.

On the CP thing...if I'd found it was lacking via the software, I was going to take some plasti-core sign material and rip a rib out of it and tape it on the bottom of the "factory" fins on the rocket. The material is light, free (bandit signs), and fairly rigid. I didn't want to have to add material/weight to the nose just because added weight lowers altitude/speed and I hate giving those things up. It was unnecessary. I decided to trust the OpenRocket model and, it seems, it was correct. Or beginners luck.

I'll try to attach a picture. I made a star gun yesterday with some stuff I had lying around. It's not supposed to be pretty, this stuff was literally laying on the floor in my shop. I just cut the stuff to length, dressed the top/mouth ends, drilled fuse holes, and welded to a base. Took me about 15 minutes, including the quick spin on the lathe to dress those mouths a bit. I made this with 3 tubes welded to a 4" x "that looks right" x 1/4" piece of steel flat bar. The three tubes are 3/8", 1/2", and 3/4" gas pipe. If you know anything about steel pipe/tubing, you know that those measurements (3/8", 1/2", 3/4") have *nothing* to do with the dimensions of the tubing (unless you cut a section to that length). I made them 6", 7", and 8" long, respectively. I made two test stars yesterday using some of my failed delay comp (roughly 50/50 KNO3/charcoal plus a little (6% maybe) sulfur). It's really close to a recipe for Tiger Tail star comp (or something like that). I made a couple about 1/2" diameter (rammed in a piece of 1/2" PEX tubing) after I added some -30 mesh (IIRC) charcoal flakes "just 'cause". I then primed them with some hot BP and dried them in the dehydrator. I loaded it all to bring home and try tonight. I shot one a bit ago. OMG! That's the coolest thing *ever*! Unreal! Beautiful! Burned out at apex, maybe 50' or so but I've got no way to know for sure.

Back to the star gun: I chose to use steel for this. I chose steel for a few reasons: 1) I have steel on hand, 2) I've been doing hobby and professional fabrication for 20+ years and have the tools and machines and the experience to make it and stick it, 3) a soft plug (star) sitting on an itty bitty bit (2-3 grams) of BP in a small-diameter steel tube doesn't scare me in the least. Now, if this was 6" and launching a 2-3# shell to 200'....I'd not be so cavalier.

I made some G1 Glitter Star something or another today (Skylighter article). It's basically BP components, some dextrin, and some Al powder, all of which I had so I did it. I didn't make any stars from it today...but you can bet your butt I'll be making some tomorrow!

Always, thanks for your time and help. I launched my first complete model rocket motor today and it worked flawlessly, and I couldn't have done it without the help I got from you and all the others who have helped me here.

--HC

Congrats!!! Homemade motors working 100% on first finned launch is very excellent success!! Good recovery, too--amazing! It must feel good to put one to Estes and their overpriced crap! What'd your son think? And yes, I'd trust the software CP estimations more than the cruder CP guestimations. Nice job!

And glad you're having fun with your new stargun--no need to worry about CATOs with that set up unless you half-fill them with flash for lift, tsk tsk. And yes, firing single stars and comets can be enjoyable and is the only way to test new comps. Suggest making some 3/4" and 1" guns for individual comets (or small bags of smaller stars). You'll soon be moving on to larger-diameter 2-3" (or larger?) mine tubes. Suggest HDPE or cardboard for up to >1" to 2", and HDPE (or lighter fiberglass--about the same cost) for anything larger; not steel at those sizes, unless you like digging holes.

Great news. Can't wait to see the launch video, even if a little far away! And it looks like I owe you a buck for that wager on your Patriot's stability, dangitall! Actually, happy to pay up. Congrats again.

Edited March 25, 2020 by SharkWhisperer

March 26, 2020

Got it done. Shot it for the first time and got it on video.

--HC

March 26, 2020

Congrats!!! Homemade motors working 100% on first finned launch is very excellent success!! Good recovery, too--amazing! It must feel good to put one to Estes and their overpriced crap! What'd your son think? And yes, I'd trust the software CP estimations more than the cruder CP guestimations. Nice job!

And glad you're having fun with your new stargun--no need to worry about CATOs with that set up unless you half-fill them with flash for lift, tsk tsk. And yes, firing single stars and comets can be enjoyable and is the only way to test new comps. Suggest making some 3/4" and 1" guns for individual comets (or small bags of smaller stars). You'll soon be moving on to larger-diameter 2-3" (or larger?) mine tubes. Suggest HDPE or cardboard for up to >1" to 2", and HDPE (or lighter fiberglass--about the same cost) for anything larger; not steel at those sizes, unless you like digging holes.

Great news. Can't wait to see the launch video, even if a little far away! And it looks like I owe you a buck for that wager on your Patriot's stability, dangitall! Actually, happy to pay up. Congrats again.

Thank you. It was a long road, considering what I went through about 35 years ago is part of how I got to have success here. There's more in that one motor than I could ever put into words. In hindsight, it wasn't that hard, but looking from the bottom of the learning curve to the top, it was daunting.

My son was thrilled. He painted the yellow on it with a brush and helped with the spray paint and then got to mash the button for the launch.

I shot a number of Tiger Tail stars and G1 Glitter Stars (comps I read about on Skylighter's site) tonight with the star gun. That's a lot of fun and we stacked them and that was more fun. I can't wait to wrap some in a ball and send that up for a break. There's a lot to learn, yet, with the stars, but getting the first taste of success is fantastic.

Thank you, and everyone here who has helped with this project. I needed the community to call on for information.

--HC

March 26, 2020

<snip> half-fill them with flash for lift <snip>

Hahahaha. No. :-|

--HC

March 26, 2020

Got it done. Shot it for the first time and got it on video.

https://www.youtube.com/watch?v=c3Fb5lvXoLM

--HC

Nice work! I think I enjoyed your excitement about the success almost more then the launch! Congrats.

Final steps in making BP motors - seeking advice

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