Can't wait to see you remove the smoke element and test it again. Also, a thin-walled steel tube sleeve in the PVC (like a heat shield) might be the solution should you use the smoke element in the future. With all of that space at your disposal, perhaps you could fire one horizontally into a fridge for entertainment value. :)
The fridge idea is funny but first I would have to find a fridge and then I would have to haul it out to the testing site... Funny idea but too much work.
Thanks for your video journal of your quest for knowledge. During my testing I have found the forward bulkhead to be the most likely to fail from a blowout. After you address the heat issue you might want to reinforce the concert lugs with some metal to prevent a lug sheer force failure. Eliminating the smoke is the right direction, as it is lit first and has a long time to transfer heat to the PVC. It may be necessary to incase that element in concrete to prevent heat transfer, clay kitty litter might work well also. If you made the smoke element small enough to allow 1/4 inch of kitty on the side walls might be just enough. Good luck with it, I rest assured you will find the answer.
There's no question at all, when you review the footage in slow motion that the failure happened while the motor was still at full thrust, and did not wait until the smoke had started.
True that it did happen early on an during full thrust. However, the smoke element is ignited at the same time that the fuel is ignited so I am still concerned that it may be causing some heat issues at the top of the motor where it is located. I could be wrong but I will remove the smoke element and make a few other minor changes next time and see.
@@rotaryrocketry If you could slip a few wraps of paper into the casing, then pour in a bit of dilute sodium silicate [water glass] and allow it to dry... This would give a decent temporary shield against heat because it would hold up to over 1000F for at least long enough to finish the burn. The paper would keep the water glass from shattering and would emit some CO2, which not only hardens the water glass, but offers an ablative form of cooling, that should emit at just a low enough volume that it does not eject the fuel from the cartridge before it can properly burn. 2 or 3 wraps of paper [at 0.003" per wrap] along with the small amount of water glass it should be able to absorb, should contribute less than 12 grams to the mass of the motor. The idea would be to insert the paper, dribble in the water glass [using gloves, since it is an alkaline product and cause minor skin irritation] and roll it around until all of the paper is wet, then let the rest drain back into the container to be used later. While the paper will not dry rapidly without heat, it will dry eventually witout heat, if there is risk of damaging the PVC with heat. Interestingly, if one had a hair dryer and aimed it down the tube at a few inches of stand-off [4 to 6 should be enough], that would likely be enough heat, while not too much heat, as you would not want the water glass to boil dry inside the paper as this would make a mess of things. The exhaust from a shop vac would do the same thing, but with a safer limit on its heat, but using a lot more air flow. I can not say how long it would take to dry, I have never tried to force dry water glass this way, and such factors as heat and relative humidity would make a difference, as would altitude. You would not want to try to vacuum dry it, because that would cause it to boil and foam up inside the casing, reducing the space for your fuel too much. On the other hand, it is possible to create a glass foam insulating liner with water glass, I've done it before with a torch, just not as a sleeve for a motor like this. I used it to insulate the outside of some stainless steel tube I was using in a solar thermal motor research project some 18 years ago, and I deliberately used a rather thick, syrupy mix and after letting it dry just enough to be too stiff to sag, I heated it rapidly with a heat gun to cause it to turn into a glass foam, thereby making instant medium temperature [up to 850F] glass foam insulation. If you can have a shape for the assigned internal volume of the cartridge, and you can mix up your own balanced mix of water glass, you can heat it to produce similar results. In theory, if one also added a pinch of sodium carbonate [soda ash] they can both expand and harden the product at the same time. I have not personally tried this as of yet, but it is on my long term 'to-do' list of research. As a side note, sodium silicate is often used as an absorbent, either in little packets marked as 'silica gel' or as cat litter [the type that looks like colored rock salt]. This will tell people a little bit about the product... byjus.com/chemistry/sodium-silicate/
Why aren't you using screws into the anchoring cement instead of relying on the probably poor shear strength of the cement? When I was a kid, that's how we successfully held in our Durham's Rock Hard Water Putty nozzles and end plugs. Note that we're all still alive and have all of our body parts because we knew what we were doing. See the classic Brinley's Rocket Manual for Amateurs and Richard Nakka's Experimental Rocketry Web Site for more info including SAFETY MEASURES.
The screw method is certainly an option... But we appear to be past the point of questioning the shear strength of the cement. Both ends stayed in (at least for the short time it was burning) on this model.
Why not tap the outside of the pipe with a large thread die. And just use a steel threaded plug and a threaded nozzle. Then maybe try Richard’s KNPSB. (If you dare!) Im trying it with erythritol instead of sorbitol. Tests at 29mm when I find myself bored with my robots.✌️
This thin wall pipe is too thin to add threads. I did develop a similar motor that had a threaded fitting welded on the end and a full steel nozzle was threaded onto the fitting after fuel was installed. It worked great. In fact, it was our most powerful motor ever and we used it in our 1000 subscriber special. But the steel fitting and steel nozzle were very heavy. This is basically a version of that motor without the heavy steel parts. As for fuel changes... We've been using a KNSU mixture since we started and I'm really happy with it and also very comfortable making & casting it. So for now, I'm sticking with KNSU.
I am aware that it typically contains around 3 to 5 percent corn starch. However, it is convenient. I do have plans for a new fuel mixture coming up that will need to be more pure so I will be grinding my own for that one.
That would likely work fine. People use a variety of sugar types for fuel. We actually tested a variety of liquid sugar products as substitutes for corn syrup and found them all to work well.
Well, since neither of you has offered any real life data, I will offer some to defend my position... I assume you are referring to the steel casing. This is a soft steel, seam welded pipe. It does NOT fragment into bits of shrapnel if the motor develops excessive pressure. You seem to think it will explode into bits like a grenade... It does not. A grenade explodes into bits because it is designed to do so. This soft steel will merely bursts open or peel like a banana. We have in fact had motors explode using this exact piping in the past before we were using the PVC liner and have seen how it burst open first hand. Furthermore... Even if something was to fly off of this motor (like a bulkhead or cap) we are a safe enough distance away that it would not be a safety issue. We all have to make our own safety decisions and assessments... If you don't want to build a rocket motor with a steel case... Then don't, it's your choice.
Neither Tripoli or our club would allow a test fire or flight since it is a violation of our safety regulations which is enough justification for my saying PVC and Stainless are both "unsafe". BALLS might allow it but 6061-T6 DOM seems to be the only reasonable material for price and ease of machining. I think a 38mm TA2 or Grade 5 titanium case might be a possibility but it requires flood cooling which I don't have. 54mm isn't a standard size, and anything larger gets really expensive.
Oh, I'm quite aware that Tripoli & NAR would not allow such a beast. Pretty much everything I do would not be allowed at a Tripoli or NAR event. Doesn't mean it "unsafe", just "unallowed". And that is why I'm not a member of either group. Myself as well as plenty of other people MUCH smarter than me have had great success with motor casing & fuels that are not allowed by Tripoli & NAR.
Fiberglass is a bad material for a liner. I'd recomend using paper-phenolic liners or if you can't buy them you can make paper-epoxy ones at home but they are less effective. Also why are you making pvc motors and puting them in a steel case when you can make a motor using only steel or aluminium?
The PVC is really only a heat shield for the steel. A while back, I had a similar steel case motor I was developing and was using a thick paper liner. The paper got burned through which allowed the heat to come in contact with the steel. The steel really didn't appreciate that... The motor exploded and went from being a straight pipe to being somewhat horseshoe shaped.
@@rotaryrocketrysome of my friends used paper-epoxy liners and they worked fine. also i used a regular paper tube from a tin foil roll and it also worked fine. i've heard that paper-phenolic liners are great.
I bought a 3' piece of phenolic liner a few years ago for a project and never actually used it. I understand it's supposed to work very well. Problem I have found with using pre-made phenolic liners or paper rolls is finding the exact proper size for the project I'm working on.
Your materials are frangible and very dangerous. If your desert videos are your in local area, there dozens of people within an hour or so of you that can help you learn how to do this successfully. It's not as an interesting video as catastrophic failures and crashes, but cheaper and more successful in the long run. You don't have to reinvent the old wheel, especially with low performance sugar motors.
I don't think you understand the purpose of what we do and the purpose of our channel. It's not about copying other peoples designs or using already proven techniques. It's about experimenting and testing our own ideas. Most times, that results in failure... But that's part of the journey. And to your point of dangerous materials... The steel casing is not dangerous. It's a soft steel, welded pipe that will either burst or peel like a banana if over pressurized. We've done it, we've seen it... It does not explode into shrapnel.
@@rotaryrocketry What is the burst pressure for your pressure chamber? Did you look up what frangible means (NFPA)? What is the propellant characterization look like? What is the ISP of your propellant? What is the mass flow through the port? What is the expansion ration of your nozzle? Does your homeowners insurance have a mitigation clause? (for not paying if your house burns down) I completely understand the purpose and risks of your channel. Do you?
Clearly not someone who will enjoy our channel. Not worth my time to continue this conversation since you clearly decided that you already know everything. Good day.
@@rotaryrocketry Clearly, the intent of my, and other's comments, regarding the materials is borne out of an attempt to help you understand the risks of the materials to avoid injuries or property destruction. Characterizing me as a "know-it-all" underscores my experience with a steel nozzle coming within an inch of taking a friends head off after a cato. Advanced high-power rockets have taken out cars and trucks. It is worth my time time to help you avoid that experience, or burning down your property. Your homeowner's insurance has a a clause that requires you to mitigate damage. If you have a propellant accident inside, you insurance company may not pay to rebuild. Few people these days can afford a mortgage with no place to live. All the commentors want you to have safe fun.
Awesome to see another test! That FrankenMonkey is looking mean.
Thanks for the video. Good luck with #3!
Can't wait to see you remove the smoke element and test it again. Also, a thin-walled steel tube sleeve in the PVC (like a heat shield) might be the solution should you use the smoke element in the future. With all of that space at your disposal, perhaps you could fire one horizontally into a fridge for entertainment value. :)
The fridge idea is funny but first I would have to find a fridge and then I would have to haul it out to the testing site... Funny idea but too much work.
Thanks for your video journal of your quest for knowledge. During my testing I have found the forward bulkhead to be the most likely to fail from a blowout. After you address the heat issue you might want to reinforce the concert lugs with some metal to prevent a lug sheer force failure. Eliminating the smoke is the right direction, as it is lit first and has a long time to transfer heat to the PVC. It may be necessary to incase that element in concrete to prevent heat transfer, clay kitty litter might work well also. If you made the smoke element small enough to allow 1/4 inch of kitty on the side walls might be just enough. Good luck with it, I rest assured you will find the answer.
That song is awesome, damn.
Thank you. I've been using UDIO.com for music and it's been really fun to see how amazing they come out sometimes.
There's no question at all, when you review the footage in slow motion that the failure happened while the motor was still at full thrust, and did not wait until the smoke had started.
True that it did happen early on an during full thrust. However, the smoke element is ignited at the same time that the fuel is ignited so I am still concerned that it may be causing some heat issues at the top of the motor where it is located. I could be wrong but I will remove the smoke element and make a few other minor changes next time and see.
@@rotaryrocketry If you could slip a few wraps of paper into the casing, then pour in a bit of dilute sodium silicate [water glass] and allow it to dry...
This would give a decent temporary shield against heat because it would hold up to over 1000F for at least long enough to finish the burn.
The paper would keep the water glass from shattering and would emit some CO2, which not only hardens the water glass, but offers an ablative form of cooling, that should emit at just a low enough volume that it does not eject the fuel from the cartridge before it can properly burn.
2 or 3 wraps of paper [at 0.003" per wrap] along with the small amount of water glass it should be able to absorb, should contribute less than 12 grams to the mass of the motor.
The idea would be to insert the paper, dribble in the water glass [using gloves, since it is an alkaline product and cause minor skin irritation] and roll it around until all of the paper is wet, then let the rest drain back into the container to be used later.
While the paper will not dry rapidly without heat, it will dry eventually witout heat, if there is risk of damaging the PVC with heat.
Interestingly, if one had a hair dryer and aimed it down the tube at a few inches of stand-off [4 to 6 should be enough], that would likely be enough heat, while not too much heat, as you would not want the water glass to boil dry inside the paper as this would make a mess of things.
The exhaust from a shop vac would do the same thing, but with a safer limit on its heat, but using a lot more air flow.
I can not say how long it would take to dry, I have never tried to force dry water glass this way, and such factors as heat and relative humidity would make a difference, as would altitude.
You would not want to try to vacuum dry it, because that would cause it to boil and foam up inside the casing, reducing the space for your fuel too much.
On the other hand, it is possible to create a glass foam insulating liner with water glass, I've done it before with a torch, just not as a sleeve for a motor like this.
I used it to insulate the outside of some stainless steel tube I was using in a solar thermal motor research project some 18 years ago, and I deliberately used a rather thick, syrupy mix and after letting it dry just enough to be too stiff to sag, I heated it rapidly with a heat gun to cause it to turn into a glass foam, thereby making instant medium temperature [up to 850F] glass foam insulation.
If you can have a shape for the assigned internal volume of the cartridge, and you can mix up your own balanced mix of water glass, you can heat it to produce similar results.
In theory, if one also added a pinch of sodium carbonate [soda ash] they can both expand and harden the product at the same time.
I have not personally tried this as of yet, but it is on my long term 'to-do' list of research.
As a side note, sodium silicate is often used as an absorbent, either in little packets marked as 'silica gel' or as cat litter [the type that looks like colored rock salt].
This will tell people a little bit about the product... byjus.com/chemistry/sodium-silicate/
Durhams Water putty makes good nozzles. Add flowers of sulphur to your mix.
Why aren't you using screws into the anchoring cement instead of relying on the probably poor shear strength of the cement? When I was a kid, that's how we successfully held in our Durham's Rock Hard Water Putty nozzles and end plugs. Note that we're all still alive and have all of our body parts because we knew what we were doing. See the classic Brinley's Rocket Manual for Amateurs and Richard Nakka's Experimental Rocketry Web Site for more info including SAFETY MEASURES.
The screw method is certainly an option... But we appear to be past the point of questioning the shear strength of the cement. Both ends stayed in (at least for the short time it was burning) on this model.
Why not tap the outside of the pipe with a large thread die. And just use a steel threaded plug and a threaded nozzle. Then maybe try Richard’s KNPSB. (If you dare!) Im trying it with erythritol instead of sorbitol. Tests at 29mm when I find myself bored with my robots.✌️
This thin wall pipe is too thin to add threads. I did develop a similar motor that had a threaded fitting welded on the end and a full steel nozzle was threaded onto the fitting after fuel was installed. It worked great. In fact, it was our most powerful motor ever and we used it in our 1000 subscriber special. But the steel fitting and steel nozzle were very heavy. This is basically a version of that motor without the heavy steel parts. As for fuel changes... We've been using a KNSU mixture since we started and I'm really happy with it and also very comfortable making & casting it. So for now, I'm sticking with KNSU.
Why are you using store bought powdered sugar?? It has cornstarch in it!!
Grind ur own sugar.
I am aware that it typically contains around 3 to 5 percent corn starch. However, it is convenient. I do have plans for a new fuel mixture coming up that will need to be more pure so I will be grinding my own for that one.
@@rotaryrocketry What about corn sugar from a Homebrew shop?
That would likely work fine. People use a variety of sugar types for fuel. We actually tested a variety of liquid sugar products as substitutes for corn syrup and found them all to work well.
very unsafe material to use for a motor case
@@benjaminnevins5211 Thank you for your opinion... but not true.
@@rotaryrocketry i think he's got a point
Well, since neither of you has offered any real life data, I will offer some to defend my position... I assume you are referring to the steel casing. This is a soft steel, seam welded pipe. It does NOT fragment into bits of shrapnel if the motor develops excessive pressure. You seem to think it will explode into bits like a grenade... It does not. A grenade explodes into bits because it is designed to do so. This soft steel will merely bursts open or peel like a banana. We have in fact had motors explode using this exact piping in the past before we were using the PVC liner and have seen how it burst open first hand. Furthermore... Even if something was to fly off of this motor (like a bulkhead or cap) we are a safe enough distance away that it would not be a safety issue. We all have to make our own safety decisions and assessments... If you don't want to build a rocket motor with a steel case... Then don't, it's your choice.
Neither Tripoli or our club would allow a test fire or flight since it is a violation of our safety regulations which is enough justification for my saying PVC and Stainless are both "unsafe". BALLS might allow it but 6061-T6 DOM seems to be the only reasonable material for price and ease of machining. I think a 38mm TA2 or Grade 5 titanium case might be a possibility but it requires flood cooling which I don't have. 54mm isn't a standard size, and anything larger gets really expensive.
Oh, I'm quite aware that Tripoli & NAR would not allow such a beast. Pretty much everything I do would not be allowed at a Tripoli or NAR event. Doesn't mean it "unsafe", just "unallowed". And that is why I'm not a member of either group.
Myself as well as plenty of other people MUCH smarter than me have had great success with motor casing & fuels that are not allowed by Tripoli & NAR.
Fiberglass is a bad material for a liner. I'd recomend using paper-phenolic liners or if you can't buy them you can make paper-epoxy ones at home but they are less effective. Also why are you making pvc motors and puting them in a steel case when you can make a motor using only steel or aluminium?
The PVC is really only a heat shield for the steel. A while back, I had a similar steel case motor I was developing and was using a thick paper liner. The paper got burned through which allowed the heat to come in contact with the steel. The steel really didn't appreciate that... The motor exploded and went from being a straight pipe to being somewhat horseshoe shaped.
@@rotaryrocketry did you use spiral wound paper tube?
No, it was a card stock material that was rolled up to create 2 or 3 layers.
@@rotaryrocketrysome of my friends used paper-epoxy liners and they worked fine. also i used a regular paper tube from a tin foil roll and it also worked fine. i've heard that paper-phenolic liners are great.
I bought a 3' piece of phenolic liner a few years ago for a project and never actually used it. I understand it's supposed to work very well. Problem I have found with using pre-made phenolic liners or paper rolls is finding the exact proper size for the project I'm working on.
Your materials are frangible and very dangerous. If your desert videos are your in local area, there dozens of people within an hour or so of you that can help you learn how to do this successfully. It's not as an interesting video as catastrophic failures and crashes, but cheaper and more successful in the long run.
You don't have to reinvent the old wheel, especially with low performance sugar motors.
I don't think you understand the purpose of what we do and the purpose of our channel. It's not about copying other peoples designs or using already proven techniques. It's about experimenting and testing our own ideas. Most times, that results in failure... But that's part of the journey. And to your point of dangerous materials... The steel casing is not dangerous. It's a soft steel, welded pipe that will either burst or peel like a banana if over pressurized. We've done it, we've seen it... It does not explode into shrapnel.
@@rotaryrocketry What is the burst pressure for your pressure chamber? Did you look up what frangible means (NFPA)?
What is the propellant characterization look like?
What is the ISP of your propellant?
What is the mass flow through the port?
What is the expansion ration of your nozzle?
Does your homeowners insurance have a mitigation clause? (for not paying if your house burns down)
I completely understand the purpose and risks of your channel. Do you?
Clearly not someone who will enjoy our channel. Not worth my time to continue this conversation since you clearly decided that you already know everything. Good day.
@@rotaryrocketry Clearly, the intent of my, and other's comments, regarding the materials is borne out of an attempt to help you understand the risks of the materials to avoid injuries or property destruction.
Characterizing me as a "know-it-all" underscores my experience with a steel nozzle coming within an inch of taking a friends head off after a cato. Advanced high-power rockets have taken out cars and trucks.
It is worth my time time to help you avoid that experience, or burning down your property. Your homeowner's insurance has a a clause that requires you to mitigate damage. If you have a propellant accident inside, you insurance company may not pay to rebuild. Few people these days can afford a mortgage with no place to live.
All the commentors want you to have safe fun.
I appreciate and respect your clarity of response.