Building a HUGE pvc rocket motor - Dan Pollino's K500 motor
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- เผยแพร่เมื่อ 3 พ.ค. 2024
- Today I'm building Dan Pollino's K500 rocket motor.
We fill it with flexi-fuel sugar fuel and test it.
I would REALLY like to point out that I don't recommend people use this video as a building tutorial because of the "explody" problem we had when testing this motor. I am hoping to solve this and be back soon with another attempt at this motor.
Be sure you understand the possible dangers involved with using PVC as a motor casing. Take appropriate safety precautions when testing ANY type of experimental rocket motor.
Nozzle washer
www.mcmaster.com/98029A037/
Motor mounting brass inserts
www.mcmaster.com/92395A116/
Dan Pollino's TH-cam channel
/ @danpollino
Interview with Dan Pollino
• Interview with Dan Pol...
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Lots of comments regarding safety. This is a great video with lots of details. Anyone building something of this size probably has a good understanding of the dangers of large scale rockets. We're adults and shouldn't need all the whining Karens crying that the sky will fall. Anyone building this should understand that distance is safety. PPE is safety. That's all.
One of the best comments I've seen in a long time... Thank you.
@@rotaryrocketry my pleasure. I appreciate all the hard work, time and money that went into creating it. Thank you
Possible subtitles for that book.
Results May vary.
You may not be so lucky.
Believe it or not.
I keep them in formaldehyde.
This dumbass makes a motor in a tube that clearly has "NOT FOR PRESSURE" written down the side, claims its a tutorial, and misleads people who don't know better. Unless your PPE includes a Bomb Suit, good luck trying to protect yourself against an accidental explosion.
@@BrainiacManiac142 I do think Rotary Rocket needs some SERIOUS disclaimers on the video. At the beginning, in the middle, and at the end.
The "problem" with PVC cased HPR motors is that they're useful for certain applications, with a cost/benefit & pro/con tradeoff.
And at the same time, they're simple enough for any idiot with zero experience, $100, a Home Depot, & a supermarket in their town, to make something capable of killing themselves with in a weekend. Assuming they don't light a few pounds of powdered/confection sugar & KNO3 Spectracide "Stump Remover" on the kitchen stove first...
Most any High Power rocketry motor is not going have a tube/body that directly resists the combustion pressure laterally.
Aluminum, stainless steel, fiberglass, carbon fiber, phenolic resin & cotton, tight-wound pyrotechnic cardboard tube... they may have a higher burst rating than PVC, but they'll still all fail if they try to contain the combustion pressure directly.
The fuel itself does most of the containment, and right as it's finished combustion, the pressure drops.
And from a launch perspective, any significant failure is going to cause a CATO blowout that will destroy the rocket. So in that sense, wanting to use something cheap & available like PVC is not unreasonable.
The issue with PVC is that when it fails, it often shatters into multiple small triangular splinters. (Which is exactly what we saw in the video)
And that is just about the worst failure mode from a safety standpoint.
Other casing materials will burst while ripping open. Often staying in one piece, or, they might fragment, but there's only 2 ot 3 pieces. Or there's countless fragments, but the fragments are tiny and light, and can't travel any appreciable distance.
If proper range-safety is followed, the additional risk from PVC shrapnel is irrelevant. And if it fails on a launch, a motor casing with a more sedate failure mode in a CATO blowout is still going to wreck the rocket no matter what.
The various high power rocketry clubs will not allow PVC motors & Sugar/KNO3 mixes at any sanctioned event. Even if range safety makes the danger at launch moot. (Although, it might take out neighboring rockets awaiting their turn...)
Mainly because the fragmentation risk with PVC in the event of some wild low-probability accident while unloading the van, or carrying the motor to the staging & assembly area happened, in the middle of spectators etc.
But, if you're launching alone, in an appropriate place, and following the best safety procedures, the "risk" to using PVC & Sucrose/KNO3 becomes one of wasting your time in hopes of saving money, or, chasing the chance of getting more launches for your money.
This was well worth watching. I have built rockets, but never the engines. Thanks for the informative video. Even minor failure is worth seeing.
I use a hot plate "Nuwave" because I can set the temp, and it wil be accurate to within 10 degrees, then I use a submersible thermometer that has an alarm on it. Thanks for the video.
Rockets are really cool and model rockets are even cooler. It wasn't that long ago when rockets were just a fantasy. Today we can build them and actually fly them. Plus the educational factors that come with it. Math, science, and engineering, so important in today's world but add common sense problem solving like you did with drilling a simple hole in your fuel coring rod and then putting a socket. You had a ticking clock and solved it on the fly. This is fun food for the brain. Much better than watching cartoons.
Awesome interview with Dan. He too was an inspiration to me in my early years developing sugar motors in my garage with my children and getting them involved. Just this past week, I have gone on to achieve level 2 certification here in NZ and am working on a lvl3 attempt. Rotary Rockets is kinda picking up from where Dan left off, keep up the great work boys!
you did great all your effort well appreciated
Rocketry is not an easy hobby once you get into making your own motors. Keep it up as I think you were getting things figured out. Good Luck!
There are glass thermometers on brass backing specially made for sweetmakers to get precision temperatures with heated sugar. Search local cookware shops (or online!) for cooking thermometer or sugar thermometer. Yes sugar gets harder if it' been heated to higher temperatures, too high and it loses any elasticity and becomes brittle (Then the core cracks and it cato's!). Near me cooking thermometers vary from £5 to £25, which is less than you spent on a banger!
Reminds me when I tried making this type of rocket fuel when I was a teenager many years ago. I heated a smaller amount than you did on a metal pan in a hot plate. I poured the heated fuel fron the pan and a little bit ran down the lip after pouring. I set it back down on the hot plate which ignited it like a fuse. It burned up the side of the pan and into the pan and set off everything in the pan. Fortunately I did this outside! Heat and rocket fuel should be done outside.!
Hint, hint, when handling R-Candy Fuel always wear latex free gloves or moisture from your hands will increase moisture content in the fuel. Even though it's nontoxic always wear gloves. If you use a dehumidifier to reduce relative humidity to at least 35-40% in a sealed room with ventilation during the build the overall humidity in your fuel will be less for longer burn motors. For longer burn lower impulse motors use sucrose or glucose sugar and sodium nitrate not powdered sugar because it has impurities, it burns cooler too.❤
You might add a final step by fiber-glassing the outside. wrap in a couple layers of glass cloth around the length of the motor and set it with laminating resin. I believe the glass will provide like 440ksi of added strength whereas pvc is under 15ksi.
I remember making this same motor a long time ago with the same result. then I switched over to KNSB and have found it easier to work with and easier to build consistently.
Did you ever try KNSB in Dan's K500 motor?
@@rotaryrocketry I did not though due to it’s consistency in making and it’s lower burn coefficient I think it would be much easier to make work.
It was too much of a pain to build that whole motor so I just started using commercial casings.
Building a rocket motor is equal parts of art and science. You did a great job streamlining the process with clear steps. Like any project of this size there is always room for improvement.
Polishing the mandrel up to 1,200 grit and pulling it at the 30 -45 minute mark may help with the sticking. I have found cooking spray works best for me.
Casting the propellant at the melting point without additional heating will result in a flexible propellant that has a slower burn rate. In this case a little moisture may tame the beast.
Props for taking on a project that I deemed to difficult for me.
For more details of temperature and hardness, check out any candy making site. I’m guessing that the ideal temperature would what’s called ‘soft ball’. You reached hard ball. If you really want temperature control, why not put a simple thermistor into the base of the heater and control it that way. Great video, even if the end result was a CATO. I’m surprised that the engine is ignited at the end of the core, most igniters seem to be placed at the nozzle.
I'm familiar with the candy stages and based on Dan's instructions, it would seem that I need to actually be slightly below soft ball. I definitely got higher than that - No doubt about it. Problem is, candy makers don't tell you how the different candy stages will burn... I guess people who make candy don't really care about what the product does when you set it on fire... weird :)
I "could" do the thermistor thing... By that, I mean it's within my realm of knowledge... But probably more hassle than it's worth. Next time I'll cook slower and stop at 200F. I really think that in this situation, under-cooked fuel will be better than over-cooked fuel.
As far as ignition location... Sugar motors are "always" ignited from the top end. I say "always" because I suppose there may be some small exception to that rule but basically, that's how sugar motors work. If you ignite them from the nozzle end, they would build up pressure way to slowly for a good liftoff.
@@rotaryrocketry use a double boiler like a candy maker. It will never get above 212. You can also use an oil bath to get more controlled temperatures.
Yeah, that's been mentioned... Except the oil thing is an interesting idea. I think implementing my current changes for fuel making "should" provide the lower temperature I'm after but the double boiler idea is always a backup plan.
Yeah, I couldn't figure that out either, the ignitor being at the top end of the grain instead of at the nozzle! No wonder the darn thing blew up like that! Back in the 90s, my pre-teen niece and nephew in Oregon were visiting, and I got some chemicals and we made a couple of candy rocket engines and lit them off in the back yard, they were totally stoked and thought that I was absolutely the coolest uncle in the whole world! My sis was happy that I was continuing their education over their winter break!
Guys melted ~4Lbs of solid rocket fuel in their garage/shop. Nice.
IF WEASELS WERE AROUND ROBERT GODDARD HE WOULD HAVE NEVER SUCCEEDED.
It would make a hell of a fire if it lit.
Thanks!
The step bit would work the best for making those holes in the PVC pipe. I'd expect that a forstner bit would be horrible. What I usually do is just put a cutting disc into a Dremel tool and cut grooves into the wall. This has worked well for smaller diameter pipes (~1" or less).
FYI, Rockite is 98% plaster of paris and 2% portland cement; this will be stated in the SDS for Rockite. It's really overpriced for what it is.
PVC pipe is pretty brittle when it's cold; I had similar catastrophic failures trying to launch them in winter vs. the same design used in summer.
Interesting, I fly plsnes & can't afford another hobby, but it sure looks worth the effort.
I said to myself after the 1st 1/2 inch hole was drilled, boy did he get lucky. The 2nd hole met expectation. Yep, even in wood the large drill will grab and tear without incremental increases.
To the few comments regarding safety,, no rocket motor should ever be thought of as completely benign. They all need to be treated pretty much like a gun, ie with safe practices. However, without trial nothing is ever learned and those that treat every rocket motor like the gun are the ones that we can say have learned.
He makes a tutorial showing how to make the motor, but doesn't bother to read the tube. The tube clearly has "NOT FOR PRESSURE" written down the side. This was an inevitable outcome. The safe practices are using proper casing materials, such as aluminium.
@@BrainiacManiac142 Well, suit yourself and don't use PVC to make a rocket motor by assuming the material can't handle any pressure at all. I on the other hand think that the material has a limit & if you don't exceed the limit the material can be utilized. I say this because I've seen PVC tubing used for firework mortars which obviously are momentarily pressurized in order to send the shell 800 feet in the air. I also have seen the shells made of short pieces of PVC blow off their glued on endcaps rather than shatter when the fuse ignites the blackpowder found within the shell.
@@migalito1955 there are types of PVC that can take pressure. This is not one of them. It’s why it has “NOT FOR PRESSURE” printers down the side. If the limit is exceeded, the PVC fractures, sending large sharp fragments at high speed. This is in stark contrast to a properly engineered aluminium motor, where the rear closure is designed to break first, to release the pressure. By willingly taking these risks, you endanger yourself and those around you.
it's possible that there were air bubbles or cavities in the fuel grain that increased the burning area.
When I looked down the core hole, the surface was perfect. Of course there may have been concealed bubbles but I really don't think so... I really think it was just cooked too hot.
Great video, great subject/project. Thank you for this! I cant help remembering that most public schools “stopped” teaching science when I was a kid in the 80’s and 90’s, depriving me of that (and this) knowledge. It started even before my time. I remember seeing “chemistry sets” advertised on tv to spark interest in science, but it all stopped quickly because of this thing called “safety,” as if the teachers were incompetent, and all children are future “terrorists.” Now that is my guess, i did not research my assumptions because “teaching” that was clearly “against policy” in public schools, and the man does not like or want educated people with independent ideas talking to other people without a license in a closed and monitored community, that costs a lot of money to be apart of. The “safety people” are responsible for degradation of our society and our country as a whole. I apologize for my commentary following your praise- but i really like this video and the first comment Im forced to see is part of a dangerous ideology that is a cancer to higher learning and it has metastasized into a cumulative and compounding force that is eating away the foundations on which our country was built- as a US military veteran I have a perspective that only 1% of the US population can claim to have, and I see the problem.
Anyway, in consideration of “people who are here to ruin everything for everyone,” and to protect yourself, I recommend adding to your disclaimer to cover any and all things… it appears that informing viewers “this is for entertainment purposes only,” is a good start. You may need to expand on that to absolve yourself of any responsibility for the stupidity of the “safety people” and their children, who by birthright are stupid too. If they were not, their parents wouldn’t be upset and actively protest to remove EVERYONES constitutional rights. Anyone with the capacity login to youtube, select this video, watch it and understand whats going on here already knows about safety! *im not being ridiculous or far fetched- i am pointing out a problem that starts in the micro and quickly infects us all at the macro level. i fear “losing” good people like you, a voluntary independent selfless public servant that is sharing information freely, that in any other context will cost far too much money and or time to learn for the average citizen like myself. Im actually below average based on socioeconomic and cultural statistics😓 please keep doing what you are doing, it is more important than ever before in ways i never even thought to think. I apologize for this rant, Please protect yourself- the enemy starts their attacks with innocuous statements like “safety…”
Thanks for a very interesting video. Keep trying, I've subscribed and sent the video URL to a bunch of my friends.
30 years ago I burnt a big hole in the kitchen linoleum of my new bride and my first home trying to make sugar rocket fuel lol.
ooooo.... I do think I told the viewers NOT to make rocket fuel in the house. These things happen :)
I married my wife when I was only 19 and thought I knew it all, were you in 1993! I definitely needed adult supervision. Still married to the same perfect woman but I could still use some adult supervision at times.
Ok, I've now seen the entire video & the test firing.
If your spot on regarding burn rate & temperture reached during fuel processing perhaps after the fuel becomes warm enough to have the consistency of a thick batter you switch the mixture to a Double Boiler where the temperture can not exceed 212 degrees F and can be left in the double boiler as long as desired under being heated.
Under this scheme it would be impossible to exceed 212 which is darn close to 210.
Good luck.....
That is a really good idea for preventing excessive heating... I had not considered that because most of the time we cook our sugar fuel to 230F. This was the first motor I've built that called for a lower temperature of 210F.
You exceeded the bursting pressure. NOT a surprise for a tube this long. As commented: two layers of 8oz BI glass cloth AKA Rutan glass cloth from Aircraft Spruce.❤❤. Total Impulse ? Burn Time ? ❤❤
Beat me to this project, nice job. I got the 'Fingers book online (used). As you point out, one does not need the templates, but there are snapshots of Dan's site on the Wayback Machine. And good hints about saving $$ here and there, too--my shop and budget seem to be similar to yours (ha ha, I too cut PVC pipe with an old radial arm saw). But I did spring for a cheap import vise for my drill press--looks like yours would take one, too--makes drilling that PVC pipe more stable, and one can bore holes through both sides at the same time. Didn't get to see your lathe, though!
Very interesting about hotter temperature making for harder, and faster burning, fuel. I can think of two reasons for both: the powdered sugar particles more fully dissolving, and loss of water by evaporation. In any case, one motivation for flexi-fuel was to be able to case bond without the fuel grain cracking under pressure. So maybe a compounding factor to faster burning was a cracked grain because of a harder and less ductile fuel. In any case, it is useful to learn that this aspect of creating the fuel has an important variable. (Another variable I've been thinking about is that corn syrups are not all the same.)
Regardless of all, this is really great stuff. The more experimenting you do, the less the rest of us will have to do.
Just to touch on a few of your points... Next time I build this, I'm going to use the 1/2" Forstner drill bit. It's only about $8 at Home Depot and hopefully will make drilling PVC much easier.
The aspect of harder fuel burning faster was only a simple observation experiment we did a few years ago... So hopefully I am correct about that. You are correct that I could have gotten cracking with this hard fuel and that would most certainly cause "Boom".
I looked through all the documentation I have from Dan and it never shows the actual container of corn syrup so I don't know what brand he was using. I suppose there is the possibility of slight differences between brands. I had also wondered about varying granule size for the potassium nitrate. Unfortunately, there is no way for me to compare my products to the ones Dan was using so I just have to go with what I have.
Would using schedule 80 PVC pipe make a difference? My understanding is that it has double the pressure capacity of the schedule 40...
No doubt it would be stronger but two issues with that...
1. Smaller ID changes the overall performance of the motor.
2. I'm following proven design instructions so I would like to get the motor working as it is designed.
DREAT video! I would suggest pouring the furl from the wok into a metal mixing bowl to keep it at a cooler level. I would also suggest a probe style cooking thermometer to take readings below the surface.
My experience with testing this fuel since 1998, if you cook it longer and hotter the fuel does become harder, however its burn rate is significantly reduced. Caramelized sugar has a different molecular makeup, and it burns slower than nor caramelized sugar. What may have happened here is your fuel grain may have gotten cracks or air pockets in it, which when the burn reaches it, acts like little combustion chambers and spikes the combustion chamber pressure. If I let motor I have made sit for a while, they would get cracks in the grain and blow to smithereens. It is best to use what you make and not store them. Nice video!
Interesting... We did some testing a while back and found that fuel cooked to 190F burned noticeably slower than fuel cooked to 230F. It wasn't really a very scientific test, just observations so I think I may do some more testing on that in the future. I don't feel there were air pockets but admittedly, the hard fuel might have cracked under combustion pressure. Glad you liked the video.
@@rotaryrocketry It takes a but of playing around with. But what happens if you cook at lower temps, is you don’t get all the moisture out. So you have essentially wet fuel. This can give a bit of a misnomer. I got a short up where I burned 6 & 9 grans of 40/60 compositions, and they were very rapid burning. It’s dry, and not caramelized. I’ll have some vids up soon. Thanks for your reply! I just subscribed!
You've got that step drill bit. Should use it
Ya know I could have used that on the PVC... Funny... It didn't even occur to me at the time.
Parchment paper is waterproof. An alternative igniter is a 10 ohm 1/4 watt resistor, apply 12v voltage and resistor gets hot & burns up, I used Cat5 solid twisted pair wire.
I don't know anything about making rocket engines. That being said, I have a question about the process. Would a thin coat of anchoring cement on the inside of your PVC rocket body help with insulating the plastic from the fuel? You could "wash" the inside with a thin solution of the cement, then let it dry, giving you a fireproof lining to your rocket body. Maybe you already tried this and i didn't see it? Just a thought from someone that knows nothing about your hobby. Thanks for the great video!!!!!
That's an interesting idea... However... In this motor design, the PVC should not see the heat until the last moment when the fuel is fully consumed. You see, the fuel is ignited at the inside core hole and then burns outward so the fuel itself is protecting the PVC from coming in contact with the fire and heat.
Your "cement wash" idea is really interesting though. In other motor designs where there are gaps between fuel cells, it would be an interesting to see if that thin layer of cement would offer any protection.
E match is also known by other names depending on it's use. Model rocketeers call it a solar igniter. Electricians call it a fuseable link. Photografers call it a flash bulb. Easy to make your own bu using 16- 18 gauge stranded wire. Simply expose the end of two wires and reattach them with a single strand of much smaller wire. When 9 volts is applied the smaller wire burns in a flash.
True... I have made them before by connecting a few strands of steel wool between two wires. That's pretty much the idea that Dan uses in his instructions for making this motor. I just used the e-match because it was quick and easy... Also, I have a pile of them laying around for making ejection charges.
How is it that the core rod was significantly above the target depth? Did the rod expand in length? Any chance the core had defects at the nozzle end? The tool you made could have been used to seat the rod? A question not a statement. Very interesting!
So you noticed that huh... I wasn't sure if I should have discussed that issue in the video but I decided not to. So what happens is that the PVC pipe actually shrinks in length when it gets hot from the fuel. The fuel temperature is WAY above the rated temperature for the PVC. I've seen that happen before with a smaller motor that was only about 18 inches long so I was not surprised to see it happen with this one. The rod was actually fully inserted into the nozzle as it was supposed to be.
that dude is rippeed.. envious
Well, I'm guess you are referring to my assistant and not me... I will pass this along to him, he'll enjoy the compliment.
you can drill faster if you use coolant to cool down the drill-bit as well as the quickly melting plastic.,
One would think that to do anything more than watch others when dealing with chemicals and using them to get a violent reaction for the energy it creates, that one would find out the dos and donts and safety procedures before beginning. Many people make slam fire shotguns and there are definitely safety concerns when doing that such as using seamless pipe for the barrel. He used schedule 40 pvc and apparently others before him have done the same with success but I agree with you in that i would have used schedule 80.
Not sure if Sch 80 would have contained that force... Maybe. But you are correct, I was following instructions so I didn't want to deviate very far from the plans.
Are you sure your "tablespoon" measure is actually a tablespoon? It seems large but the camera might be playing tricks. A tablespoon is 15ml and a teaspoon is 5ml. There are some weird measures that have 2 TBSP size for instance. Or non-standard acronyms.
Absolutely LOVED the video. You just got a new subscriber. Do you by any chance have a .eng file for that motor that I can use in OpenRocket?
Welcome to the channel :) I made a .eng file so I could place this motor in a rocket design but the file does not contain any thrust data. It's only for size and weight. If you want that info, I would be happy to share but if you are looking for thrust data, I don't have it.
@@rotaryrocketry Yes please send me what you have.
Any hints to the different cooking temp video?
Hopefully with the next few months.
The step bit you had at the beginning should have worked for your 1/2" holes in the pvc. It cuts in a similar method as the forstner bit and will cut thin materials without grabbing.
Yeah, it's a tablespoon. Problem with measuring anchoring cement with measuring cup is you don't know how hard it is compressed so you'll never get the same exact quantity each time. I typically just add water a bit at a time until I like the consistency.
In hind sight, that's a good idea. But for some reason it never occurred to me to use the step drill for that part. Live and learn.
You should try those temperature dots the other guy used and cross check with the digital thermometer. You may find that the majority of your mix is still way under 200⁰. I'm most likely wrong, but it's a variable to eliminate.
Oh, I'm very confident the entire mixture was way over the 210 target. I knew it at the time but there isn't anything you can do once it is overheated. Well, other than start over... But I didn't want to do that.
It is unfortunate that you need so such a big sugar motor for k impulse... (compared to apcp).
I would be really interested in seing one of the motors using richard nakka's rnx-57V propellant (or maybe rnx-3)!
Or maybe you could add Aluminum to the flexi-fuel.
True... Sugar motors tent to be pretty large for the amount or thrust provided. But I like them because of the cheap, simple ingredients. I've read about Nakka's epoxy propellants in the past. Really interesting stuff and maybe something I will look into in the future. Problem is, the West System epoxy is actually pretty expensive.
Ohh that saw reminded me of my dads old dewalt. Had no brake stop and the blade takes a very long time to spin down. He almost lost his finger on a mishap with the saw off. Cut half way through his middle finger. After that he kept a board 1 inch wide nearby to press against the side to stop it after use.
Fuel Baking: MEATER Plus wireless cook thermometer, with Smart Phone app.
I looked it up... Very nice... But a bit expensive.
Any advantage to using sched 80 ???
Good question... 80 is obviously thicker so "should" be a bit stronger but that would also add to the weight. I was following Dan's instructions and he was using Sch 40 for this motor so in theory... It should work.
i built 6 inch pvc sugar rocket but it starts moisture inside and becomes wet ,how to make dry fuel which didn't expose to moisture
I am not understanding your question because of the wording. If you are using cooked sugar fuel like we make, you do have to seal the end of the nozzle when storing it so it does not absorb moisture from the air. But I don't think that is exactly what you were asking. Not sure what you mean by "becomes wet". Can you explain a bit more?
@@rotaryrocketry yeah you got my question rightly,thanks ,I am using 65gm kno3 with 34gm sugar and 1gm iron oxide,but only problem it absorbs moisture
Ah... o.k.... Well, just keep the motor sealed air tight until you are ready to fly. Putting a plug in the nozzle hole works or just tape the nozzle closed.
Are you not using a 12 inch saw blade on your radial arm saw?
No, that one is only 10.
@@rotaryrocketry My machine is a 1956 model [not sure what year yours is] and I run a 12 inch, 100 tooth blade.
Something is maybe wrong with my motor though, as it bogs easily. [even with a 10 or 8 inch blade]
Eventually, I aim to open it up and see if there is a problem with the wiring, but right now, I'm busy with so much other stuff, I just limit how much I use it so I don't overheat the motor and destroy it.
Also, I suspect mine has been dropped or shocked somehow, because all of the right angle positioning points are between 0.5 and 1.2 degrees out of square.
Re-squaring these things takes a lot of specialized work.
What I will end up doing is taking those parts, opening them up on the mill, and then making a special insert that is right on dead center, and make sure that the setting marker is also dead on center.
When I am done with it, it will look [as much as possible] like it is on the showroom floor.
I sure hope this doesn’t damage amateur rocketry. How do you launch high power rockets made with PVC cases where NAR and TRA don’t allow them?
You don't launch them at NAR and TRA events. I am not a member of either of those organizations so no problem there.
So do you get FAA clearance independently?
@@hikerbiker32 Anyone can apply for clearance... It's just a simple form. The place were I launch has an established flight ceiling due to a local group that launches there each month and I have never launched anything that comes even close to the max ceiling.
What about using a double boiler when mixing the fuel? That should provide more even heating.
That is a really good idea for preventing excessive heating... I had not considered that because most of the time we cook our sugar fuel to 230F. This was the first motor I've built that called for a lower temperature of 210F.
I've never seen Sched 40 pipe burst. That was very sobering.
Instead of a wok you might use a cast iron pan on top of an induction cooktop. Some of them have fairly precise temperature control...which is the beauty of using induction cooktops.
Yeah, that PVC is something spectacular when it blows. Induction cooktop is certainly a good idea but I was really trying to follow Dan's instructions as close as possible and that's why I got the wok.
On large pipe like that it's best to glue both pieces to get a better bond. Pipe inch and a half in less it's not a big deal
Yeah, I saw that when I was editing the video... I really did mean to put glue on both sides. Sometimes you get so concentrated on shooting the video that you forget things :)
you gotta remember that once your pan gets to your desired temp... it will continue to rise for a little bit. so if 210 is the goal. stop it around 200.
Yeah, that's part of the plan for the next attempt.
If your trying to get to 210F, why not use a double boiler system? water boils at 212F and IF you need it get it to a higher temp you can add slat (or other substances) to raise the boiling point in a controlled means.
Yup, it's been mentioned a few times. That's definitely a backup plan. I really would like to get it working using the wok because that is how Dan was doing it when he was building these.
Why you dont put red ironoxide in to it like 1~2% by weight?
Well, I need to get it working and not exploding before making adjustments to the fuel.
Too bad comments are turned off on your how to get potassium nitrate video. I've been using Seed Ranch for years, but since you took the time to post these videos I used your link this time, so hopefully you get the credit.
Back in the day I got the stuff, and other landscaping/farming chemicals, for $15/50lb from the farming chemical supply, just fill up the back of my truck with bags and bags of everything.. Those days are gone as far as I know.
Little story about the Potassium Nitrate video you're referring to... A few months after I posted that video, I went to log into my affiliate account with Seed Ranch and the account was gone. I tried to contact them and they didn't respond. I tried to setup a new affiliate account and never got an approval email. I don't know what's wrong with their system but I got fed up with it and I "thought" I had set that video to Unlisted. It seems that maybe I forgot to save the settings after changing it to Unlisted because I just checked and it was still set to "Public". Well, I appreciate you trying to help out by using our affiliate link but honestly, I does nothing at this point. Oh, and I had disabled comments on that video because I didn't want people to complain that the video sounded like a commercial :)
that things gonna have allot of juice when you fine tune it.
PVC is more brittle than ABS, that's why you see so many PVC potato launchers shattering into splinters. ABS is more elastic - that's what I would use if I were making a rocket motor out of plastic tube.
Interesting idea... I've never seen a motor made from ABS. It may be a bit less brittle but I do believe it is significantly weaker. You've given me a good idea for a video though... A comparison.
You can buy the coupling without the ring and it's called no hub.
Interesting... Maybe something for purchase on-line but they only have the ones with the ring at all my local hardware stores. Good to know though.
I also add iron oxide and magnesium in my kno2
Polish that coring rod. Mirror it and you will be able to get it out easily the 220 sand paper was actually roughed up the rod
Good idea... I'll hit it with some 1200 grit before the next build.
@rotaryrocketry get a buffer and compound the closer you can get to a mirror the better it will not stick
A couple things I'd change. Instead of the press in threads to mount motor in rocket I'd use stainless blind rivet nuts. They would not allow anything through when poring in propellant plus by a good anchor to bind everything together. Above all I'd use a induction cook top so you can have a exact temperature without guessing at when to turn heat off. Lol and next time just take small cuts with the radial saw Instead of walking to bandsaw making exact steps. Hindsight being what it is and all..lol
Yeah, in hind sight, I probably just should have cut that part out about the radial arm saw cut depth. If I still had my 12" radial saw, that would not have been an issue. I think I wasted time talking about a problem that was only specific to my particular saw.
You sure blew it.
This is a classic case of "Two things being true at once."
PVC is indeed inferior to cardboard for most motor or pyrotechnic applications.
Well wound, tight, high pressure cardboard for motors and pyrotechnic use can and do exceed Sched. 40 PVC pressure ratings, peak & sustained by miles. And they don't shatter/fragment if they do fail.
That is just normally irrelevant because you can't use cardboard tubes for plumbing applications. Even in light duty residential plumbing, you'll notice that PVC is used as unpressurized drain pipes, and rarely, if ever, as pressurized supply pipe.
But, its also irrelevant in single use high power rocketry motors, as the proper cardboard tubing in the sizes and lengths needed is hard to get, doesn't even exist, or if it does, it's expensive.
PVC, despite being extremely mechanically inferior, is cheaper and readily available in multiple sizes, and with useful adapters & fittings, because it enjoys massive economy of scale. The basic US plumbing market is thousands of times larger than HPR or pyrotechnics.
So, the surface area of: "PVC IS DANGEROUS!" Is kind of a: "Yes vs. Yes*, but..." sort of thing.
Yes, PVC is dangerous, especially with a basic Sucrose/KNO3 mix, because anyone who's ignorant of the details, procedures, best-practices, basic & advanced rocketry safety, or a willfully stupid person who ignores them... it's indeed dangerous as hell. And the ignorant, or the deliberate idiot... they can get 98% of everything needed from a big box hardware store & a supermarket.
Or...
Yes* but..., PVC (& Sucrose/KNO3) is dangerous, but a lot of things are dangerous, but arguably "worth doing." Scuba diving, skydiving, race car driving & drag racing... all sorts of things, that with knowledge and practice, you can get an acceptable risk/reward ratio.
The issue is that in this video, he understands and follows all other possible precautions, that makes a Sucrose/KNO3 motor failure merely a disappointment. He has a remote launch/ignition system, and gets several hundred yards away, and went through the effort to travel to a large dry lake bed somewhere in the SW US. The flipside is the jackass that ignores everything but the most basic mechanics of the process outlined, and does it in the backyard of his inner-suburb house on 1/4 acre lots, and doesn't even try a test stand firing, but instead sticks a big broomstick on it like an enormous stick-dragger bottle rocket.
There is a REASON, more than one actually, you can't fly a PVC cased Sucrose/KNO3 engine at any sanctioned event by the various HPR organizations.
Sucrose + oxidizer has a very steep & exponential pressure/combustion curve that's very "touchy." And there's many variables besides the mixing/melting heat, and the solid fuel hardness.
Further, the chemistry of producing "rocket sugar" it is very imprecise. And most people don't consider if there's any chemistry involved at all.
Pyrolysis in the heating & melting produces caramelan & related molecules, plus the volatile things like diacetyl, maltol, and others are in the mix, and have unknown or different combustion rates with the KNO3. And even if the target temperature of the entire blob or "dough" is constantly measured to stay well below the auto-ignition point, and the caramelization point of Sucrose, SOME of the Sucrose will caramelize/pyrolyze in small but unknown amounts, because even if the target temp overall is 210° F, the heating surface needs to be much higher than that to get the mix to 210°F and keep it there.
And Sucrose/KNO3 is also very sensitive to the core combustion surface area & diameter, nozzle opening,
But, at the same time, there's a REASON why people like this channel's owner are trying PVC & Sucrose/KNO3 despite the enormous downsides. Namely, because HPR is damn expensive, and they can try to compensate for a significantly inferior fuel/oxidizer & casing material with skill, testing/experiments, knowledge, & exacting safety procedures.
WOW... I don't have anything more to add to that.
You have the same kind of radial arm saw as I have!
Way cool! (~_^)-b
If you have any air pockets in your fuel, the motor will fail 💥.
This is why they don't use PVC to launch fireworks. ABS pipe is readily available.
Hmmm... Never seen anyone use ABS for rocket motor casing. Not saying it's not used, just never seen it. PVC has a pressure rating... Low... But at least some kind of pressure rating. ABS is basically designed for zero pressure.
@@rotaryrocketry OK I mis-spoke. The ones they sell for mortar tubes are HDPE sorry for that.
@@aculasabacca oh, thanks for the update . I'm gonna look into that.
@@aculasabacca hdpe doesn't fragment like pvc but it is very flammable so there is a trade off.
Needed a ALU case. Thanks for sharing
just a warning : rocket fuel will explode from concussion (I know I have parts missing from my left hand) so hitting screw driver is not recommended🤕 also measure the wok temperature as well as the fuel mix!
Yeah my friend don't strike the mix only press it slowly, shit bad accident hope your well today though
fascinating but unfortunately once I noticed the music it became unwatchable. I wonder why we all feel the need to add music.
pancake mix.....yum.....booooom.....lol
Yeah PVC is weak , I used to use 1cm thick cardboard cylinder about 25cm length 5" diameter,thick boy ,they went hard with a huge shower of sparks coming out ,it was outta sight ,lost it and no footage 😭😅
Instead of adding that much weight with the coupler to reinforce the motor by the smoke element why not just line the motor body with a thin sheet of metal, like a cut up soup can.
I suppose other methods may work I was just following Dan's instructions and he has successfully flown that motor many times. The motor is VERY heavy so the weight of that one coupler doesn't make much difference.
Why do I wanna attach a nose cone and fins to the motor alone
Probably because you're just about as crazy as me :)
Has anyone tried using either honey or molasses instead of corn syrup? How about putting corn starch into the mixture? That may keep the grain from getting too hard and cracking. One could also try stirring in some coconut oil to keep it soft. And rubbing the pouring core rod with a wax of some kind or mold release agent would be better than WD-40. Or wrap it with a long piece of waxed paper.
YES !!! We have used Honey, Molasses & Brown Rice Syrup. They work! Here is a link to the playlist:
th-cam.com/play/PLdExiIqOZ0llJQ42u5XqHqHTp8298Ze5z.html
Not sure what the benefit of corn starch would be. It would not help with the combustion process... Pretty much just a contaminate in the fuel that would take up space where other beneficial ingredients should be.
Coconut oil is an interesting idea but never seen it used. Maybe it's got some possibility.
The rod was really not as stuck as I originally thought. It was really just the small bit of fuel that had hardened around the rounded end. Other than that, the spray oil seems to have worked very well. Certainly a mold release product would work well too but WD40 is cheap and simple.
Wouldn’t a double boiler come in handy for the 210°
Yeah, it's been suggested a few times. I'm gonna try again with the wok but cooking low and slow. Double boiler is certainly a good backup plan.
This channel is great. It is the more, step by step detailed explanation in the web to make rocket motors.
Its not great. It promotes unsafe practices. PVC is a material that is entirely unsuitable for this application. This should not be followed as a tutorial.
Thank you. And to all those PVC haters... PVC motors are safe if built correctly. I have two PVC motor designs that we launch regularly and they are great. And we are ALWAYS a safe distance away, even when using a proven motor design.
@@rotaryrocketryyou ahould probably adress the fact some people took it as a tutorial and some of those could be quite underexperienced. but in general yes you are correct with the precautions you listed it would be safe, just try adress the fact it could be very unsafe without the precautions
@@justanother3dumbasses I am pretty sure the test scene will dissuade a lot of people from working with larger home built rocket motors.
Obviously this man lives in space so theren no NFPA
Lets celebrate the 4th
For anyone watching this and are thinking of making something similar, please do not follow this video as a guide.
PVC rocket motors are incredibly unsafe and should not be made. Deadly high-speed shrapnel can be seen in this very video, and is why motors like these are banned from all TRA launches.
"10-10.2 Non-metallic cases shall not be made of brittle materials which may rupture into sharp shards, such as PVC. "
There are many other channels and videos out there that show and respect proper safety code. Hell, there's even commercial options out there who make and sell everything you need for propellant research that comply with TRA safety code.
There is no excuse for making literal pipe bombs like shown in this video besides valuing a few extra dollars in your pocket over your own life.
I’m a new TRA member. Can you guide me to some good information.
I know the best method is to find an experienced mentor, I just have not found one local enough to make the situation work.
@@hughobrien4139 I'd start on Richard Nakka's site. He has an insane amount of good info there.
BPS Space has made a bunch of videos in the past year that go over fundamentals and testing methodology.
Charlie Garcia is another good one, has made a few videos on solid rocket motor design and simulation.
Rocketry communities like r/rocketry reddit and discord are other good places to find answers / ask questions and learn from others.
I'd really recommend you find a mentor if you want to go beyond research and start manufacturing anything.
Really easy for this stuff to go sideways very quickly (ask me how I know). Good to have a mentor there to oversee and make sure nothing catastrophic happens.
Riley gives some good info there. And don't be shy to ask questions on TH-cam channels that are doing similar things to what you want to do. I have found amateur rocketeers online to be friendly and helpful.
I will tell you this... TRA does not allow PVC case motors and although they do allow sugar fuels, they do not allow the type of sugar fuel that we are making on our channel.
A few comments... First off, I am not a TRA member and not launching at their events so I am free to make whatever I wish. Sometimes it's not about following the rules of others, for us, it's about the fun of experimentation.
As for the "deadly shrapnel"... Well, I guess that depends on how close you are. People who develop and test grenades are probably not dumb enough to stand next to it when testing a new design. We are ALWAYS a safe distance away when testing or even when launching a proven design.
We have a few PVC motor designs that we launch regularly and they work great every time. PVC is safe when the motor is designed and built properly, that has been proven my many people much smarter than myself.
As for following this video as a guide... Well, the explosion at the end should really be a clue that maybe you shouldn't follow what I did unless you are looking for the same results.
@@rotaryrocketry Experimentation is fine. The issue I had with your video is that after your motor failed and the failure mode was clearly overpressurization, your solution was not to replace your casing with something with a larger safety factor or implement some change to significantly reduce chamber pressure like massively widening up the nozzle throat, but rather to discuss how in the future you would manufacture your fuel differently so it will likely burn slower.
If your case's safety factor is already so close to 1 that a slight variation in propellant production and thus chamber pressure would cause such a catastrophic and dangerous failure, then there's already a fundamental design flaw here. The fact you are not addressing it makes me very concerned about your attitude towards safety, hence why I harped on it in my comment.
Coupling this with the rest of the video that lays out step by step how to make this motor, this comes off as a very dangerous how to guide and not a summary video showing off your experimentation.
I'm glad you are keeping a safe distance from these motors when they fire, I just wish this safety culture was emphasized more in your video and in your design process.
PVC can be done safely yes, especially when using very low pressure designs with smaller quantities of fuel and massive stand-off distances.
Considering others in the comments of this video and your other videos showcasing PVC motors seem to view your content as guides or at the very least research material for making and testing their own rocket motors, I think you should take a more active and vocal stance about the inherent safety concerns present with PVC rocket motors and why they are banned by rocketry orgs like TRA, and lay out how you are keeping yourself safe while testing them.
Or, you could simply switch to a casing material that isn't an inherent safety risk, is TRA compliant, is reusable, and can easily withstand the pressures you're working with, like aluminum.
As a side note, I would highly recommend you move away from casting directly into your motor casing and making one monolithic grain, and instead move to a multi-grain design. Your going to get a very progressive burn curve with a single monolithic grain, as well as a much higher peak pressure.
I'm not so sure the motor would have exploded if it was in a rocket. I think your testing set-up was a major contributor, if not the whole reason the PVC failed.
Here's how to see what I'm talking about:
Set your video at 1080p resolution.
Stop the video at the first frame of the explosion (about 1:14:40)
Reverse the video two times (two frames before the explosion). Let's call it Boom-2.
(on TH-cam reversing by frame is the key that has a comma (,) and a less than symbol ().
Cycle back and forth between Boom-1 and Boom-2 repeatedly.
You'll see that the top of the motor compressed itself downward by about 3/16ths of an inch before failure. The metal bench, where you clamped-in the motor, was driven down about 1/8 inch. These are just approximations, of course.
The motor was driving its nose against the bench until the bench couldn't give anymore. The thrust was so powerful the PVC compressed itself downward until it failed. That corner-leg of the bench was stuck in the ground after the explosion.
I think if the motor was in a rocket, with no immovable force against its nose, it may have survived. The PVC wouldn't have linearly compressed itself to failure.
That's my theory. Your thoughts?
Interesting theory. My thoughts...
1. Testing motors in this way is very common, especially when trying to get a thrust curve.
2. I pulled up my original footage and reviewed it frame by frame in full screen. I see that one frame before the explosion it does look like both the motor and the test stand are pushed down about an 1/8 of an inch (just an estimate). That would not be too surprising based on that amount of thrust because we are on a dry lake bed and the legs of the test stand often get pushed into the soft surface.
I guess I would have to say that my opinion is that the motor did not "compress itself into failure" but I see where it is an interesting idea that may have merit.
So one good thing about your comment is that I had no idea you could more forward and backward frame-by-frame on TH-cam until now!
@@rotaryrocketry Hey, at least you learned something about TH-cam. LOL.
If you look closely, it appears the top of the motor moves slightly more than the middle or bottom moves. That means it was compressed - or they would have moved the same amount.
Yes, of course, it's the way rocket motors are normally tested. But with PVC, being so brittle, I don't think it's the best way to test it. I really think the PVC was compressed against the bench.
Think of a section of PVC in a hydaulic press. Pressurize the inside volume of the PVC almost to the point of failure (simulating the fuel burning). Now start the press applying linear force, and it will fail quickly.
I still think it wouldn't have failed if it was in a rocket with no immovable force on its nose.
But, even if I'm wrong, it's still fun to theorize.
Ya know... I gave this some more thought and I'm really seeing what you mean. Unfortunately, I would have to design a very specific testing stand to hold it a different way... Kinda like it would be held in a rocket with the threaded inserts in the nozzle. Gonna have to give that some more thought.
@@rotaryrocketry Here's a quick and cheap testing apparatus. Use a section of 3 inch PVC pipe an inch longer than the motor. I guess that's about 36 inches. Put that through your metal table. It could rest on a scale if you want to get thrust measurements. Drop your 2 inch motor into the "missile silo". Connect the motor to the silo using the threaded inserts at the top of the assembly. Now the nose of the motor is floating an inch above the bottom shelf of the table and is applying force through the bolts at the nozzle position rather than smashing its nose into the table.
Keep in mind, the down-force at the nozzle-bolts will be much greater than the motor would experience in a real rocket flight. But at least the PVC body isn't compressing itself linearly while the pressures inside are high.
The downside is you can't see the motor body during the test. The only way you could see it would be to replace the PVC "missile silo" with a strong frame, or cage. Or, if the silo was transparent...do they make clear, strong 3 inch piping material you could use instead of PVC? Might be worth checking.
I'd be interested to see what happens to the 3 inch PVC silo if the motor goes boom. At least it won't cost much to replace it if it gets blown up too.
Just my initial ideas - maybe they will help you create something that works.
@@thisisreallife5086 The answer to observing the motor casing during testing is to use a strong mesh cage around & supporting it.
Also I think you're on to something about the motor mounts, I suspect that a "strongback" frame connecting the nozzle mounts with the forward bulkhead mount would change the scenario that played out.
dang. Is this close to an L motor? I have a few L motors at home that i need to use for my level 2stuff and my L 3 coming up haha
I don't actually have any thrust data for this motor. Dan has it rated as K500 so I'm guessing he measured the thrust curve at some point to rate the motor.
@@rotaryrocketry next question, should I cook this inside or outside? I live in an apartment and all I have is a stove top so I'm wondering if I should buy a small element and see if I can cook it outside
Really recommend outside. It puts off some fumes but I am not aware that the fumes are harmful. But overall, a good idea to cook sugar fuel outside. An "accidental" ignition of the fuel would be very dangerous in the home. Even if you have a fire extinguisher, there is an interesting problem here... The fuel contains it's own oxygen supply so even spraying it with a fire extinguisher will not extinguish the flames. Please don't burn down your apartment building :)
I would also like to point out that I would not recommend you make this motor by following this video as a tutorial. As you saw at the end... It did not end well. I really need to figure out exactly what went wrong and how to fix it before anyone should attempt this build. I do think it was the fuel cook temperature but that really needs to be proven.
@@rotaryrocketry outside it is 🙂 I'll do it at my dad's place where we have plenty of room on the driveway
I like the way you explain, but please!!!! please!!! invest in a microphone!
The scale 0.1 is more precise not more accurate than a 1.0 scale.
A 5 shot group at .1 inches is precise, but if it is at the 1 ring then. it is not accurate.
Bomb making 101
There is just no way PVC is the right material for the main tube. The inside of a rocket motor gets hot. Plastic melts.
PVC can be used for motors... That's been proven. And I will point out that I was following instructions for a proven design that Dan Pollino has launched many many times. The PVC does not see the heat until the last moment when the fuel is fully consumed. The fuel is a single pour so only the core hole is burning.
You didn't mention the potential of rabid swarms of spider monkeys interfering with the process.
So disappointing.😅
It does seem a pity I missed that... How could I have been so blind :\
@rotaryrocketry I have some suggestions regarding potential reasons this rocket blew up:
1) Hard propelling fractures easily- It is highly likely that using a chisel to "square up" the end fractured the propelling. Also, along this line, using the power drill to rotate the coring rod also likely created cracks. Another phenomena that may be at work is combustion vibration/ thrust oscillation, causing the propelling to fracture. Using WD40 as a mold release agent might not be the correct substance, as it appears not to have kept the propellant from adhearing to the coring rod. I suggest using parchment paper wrapped around the coring rod on your next attempt.
2) Schedule 40 PVC only has a working pressure of 400psi. Have you modeled the architecture in Burnside (open source rocket motor simulator)? If not, that may point you to another source of the motor failure.
It may be that the sugar motor size may be approaching the size where reliability is not achievable without frequent catastrophic failures. There is a reason one doesn't see sugar/KNO3 motors used in commercial motors by any manufacturer.
As a parting thought, you don't see commercial solid motors using black powder above an E or F range, likely largely due to its propensity to fracture. Here's an important point; if the completed motor had been dropped, or fell over, that alone could have fractured the propellant and caused the explosion.
A cousin of mine dropped a D motor once. I told him I wouldn't put that in a rocket I wanted to fly more than once. He ignored my warning and put it in his new rocket. It went up 30 feet or so and turned into confetti.
In the defense industry, if any part of a missile is dropped, it is scrapped. I live by this rule. I hope you find this missive useful.
All great info... Thanks... Just want to touch on a few of those items...
Certainly possible the fuel cracked under pressure after ignition. That was my fault for cooking it too high temp. I was SUPER careful when chiseling the top. And also very gentle using the impact gun on the coring rod. Truth is, the coring rod was only stuck because of the fuel around the bottom rounded end. Once that broke loose, it came right out. So the WD40 seemed to work well... Just not at the tip.
I would point out that this is a proven design that Dan Pollino used many many times. In fact, he even used it on a nationally viewed TV show that he was hired for. So I know it works reliably when built properly... It's the "built properly" part that's tricky :)
I was SUPER careful with the motor after casting fuel... I did realize that if I ever dropped it on the concrete floor then it was all over. I was originally going to have my assistant toss me the motor on camera for the intro and then decided not to do that just in case I turned into butter fingers and dropped it.
PVC is a bad idea and violates the NFPA.
Was not aware that the NFPA was involved with amateur rocketry. PVC motors can be made safely. That has been proven by myself as well as many other amateur rocketeers. Granted... This one did not go according to plan... But that's why we experiment. It's also why we take the appropriate safety precautions when testing things like this.
@@rotaryrocketry Dug into NFPA 1125 section 7.4. Turns out it's not prohibited there. Oops. Sorry for the FUD.
Your honesty is appreciated. I do realize that PVC casings are prohibited at TRA and NAR events and I have mentioned that before in some of my other motor build vids.
this is horribly unsafe, pvc is brittle by nature and fragments very easily under pressure making any motors with pvc is concerning at best
PVC motors can be safe if designed and build properly. I have two smaller designs that we launch regularly and they work great every time. Granted, this one was a bust but that's why we experiment and that's why we take appropriate safety precautions when testing.
@@rotaryrocketry you should adress the unsafness of this because some people took it as a tutorial
@@justanother3dumbassesPoint taken I will discuss the potential dangers in the followup video.
@@rotaryrocketry thanks man , im not trashing on ya for just using pvc, im just tryna make sure people dont get hurt trying to replicate this video
For those safety Karen’s out there, if you don’t think you can do it safely, maybe knitting is more your speed.