I found him exclusively because some other RUclipsr copied his video and he called such RUclipsr out on the comments. So I'd say the algorithm isn't helping a lot...
I'm commenting because yt promotes content that gets comments and I want your channel to succeed! I'm in school studying engineering right now and it helps so much to see these concepts in action.
You may consider using one of those squishy ear protection devices to plug the nozzle... This will hold the e-match in place and secure any loose black powder, when in normal launch configuration orientation.
The LASQAD (loose and sloppy, quick and dirty) method for finding the area under the curve, insert the image of your graph into a Fusion360 CAD canvas, scale the dimensions and select the find area command.
The simplest way to integrate over a dataset in excel, I think, would be to sum up all your data points, and then multiply by the length of the timestep. Edit: Doing that with the data you linked between the marked start and end points gives me ~50.1 Newton-seconds of impulse, so the motor would be a class F, and your specific impulse is 68 seconds (an exhaust velocity of 668 m/s).
I've just done the same (worked out average thrust from data points, although changed start and end points you labelled) So can back up Zuthal's Maths Total Impulse = 51.61 Ns Isp = 70.23 Sec Eff Exhaust Vel = 688m/s A smaller nozzle diameter/high chamber pressure should yield higher exhaust velocity and efficiency
It seems like a lot of people are just calculating the total impulse, which I agree is around 50 N-s. This isn't the full story however, specific impulse or Isp is better way to gauge the performance of a rocket. Isp = I/(m*g0), I being the total impulse, m being the propellant mass, and g0 being the local acceleration of gravity. propellant mass is 75 g (0.075 kg), g0 is 9.8 m/s^2, and I is 50 N-s 50/(0.075*9.8) = 68 s. Pretty good Isp for a sugar motor. Typical estes motors can range from 50-80 s. The space shuttle SRBs were around 250s. A cool program to check out, ProPep 3 uses thermochemical calculations to give you the optimum Isp for a particular propellant mixture. It also spits out other parameters that can help calculate the ideal nozzle expansion ratio. There are hundreds of chemicals to choose from it really helps when designing hobby motors. www.rimworld.com/loggerusb/propep3/intro.html
I've done some calculations in R and seems like the area under that curve is 5107.915 g-s with absolute error < 0.55. The error (which is really small) is due to the adaptive quadrature method used for evaluating the area. It could be a little bit higher because of the Hermite spline interpolation done on the data, but still I don't think that could be problematic at all! The area is calculated on the raw data given, I don't know if there was some scaling to do beforehand So the result comes out to be roughly 50 N-s
Yeah I calculated 5096 g*s, in Excel. I just did rough area calc by taking difference in time data points * thrust data point and then summing them all up. riemann sum.
@@PaulHollandWheels Being the data without any error, the only error is in the evaluation of the area under the points which is given directly by the function in R! The resulting plot is very well-behaved so I would expect the error on the area to be small
@@Wompylulz I was just giving you a hard time . I'm in awe of people like you I really have no idea and it's right or wrong I don't even know for sure what the equation is I know it pretty cool to be able to do that though😉
Copper oxide works great for color in AP based motors, but on nitrate-sugar based motors there is just smoke :(. It does increase the burn rate a bit though! I will be using copper oxide in some future videos on AP motors.
@@ElementalMaker As you probably know, it is because the particular 'ammonium-based solid oxygen' you are referring to has Cl in it and can therefore act as a chlorine donor.
Area under curve would be total impulse(just a sum of all the data points divided by the number of samples per second). To get specific impulse you then have to divide by weight of the propellant burned during that period.
I got a hair lower using excel but not far off. If rounded up what I get comes to 5kg so yeah not bad for a sugar motor with too big a nozzle. He's into midpower with an F motor.
I have to disagree with this value. Just by "eye-balling" a close up of your chart...ie: length of burn ≈ 1.15 s and the MEP (mean effective pressure) appears to be ≈ 2500 g so the product of these two would be the Impulse (area under curve) ≈ 3000 gram-sec or about 30 N-s. The MEP can be judged fairly accurately by eye, if you imagine a horizontal line that would split the rocket engine's graph in half area-wise. I estimated this line to be at 2500 g.
For the area under the curve, just sum all the data from START to END, and multiply the result by the timestep Δt (time between two consecutive measurements). A = ~5098 [grams-force seconds] = ~50.01 Newton seconds That's because you're building the area from little rectangles. Every rectangle has height=value in grams-force and width = Δt. => Area of the rectangle is Ar = height * width = value * Δt So we just sum all the areas: Total Area A = ∑i (Ar_i) = ∑i (value_i * Δt) But since Δt is the same across all rectangles we can simplify that to: A = Δt * ∑i (value_i)
@@ElementalMaker Yeah, that's why I like discrete math stuff xD I've also made a spreadsheet with graphs and other cool numbers. Maybe it could save you a little time, so you may want to check it out: goo.gl/n1HqdH Thank you for the good content!
@@ElementalMaker Use rectangles where the curve goes through the center top of the rectangle. This approximates better because it takes the somewhat triangular section of the segments into consideration. You can use different width rectangles - as long as you also use the appropriate time for each segment. It is even possible to use horizontal segments, or a combination of the two.
Excellent video and beautiful test!! Just a recommendation, for best results during the measurement, you could put the test device in a rigid surface, because I suspect that the grass absorbs part of the rocket engine energy 8:32 and consequently you will measure less thrust (or a different curve). It would be curious to see if there is any difference. Your channel is awesome! Regards.
Thank you! Yeah I was hoping the 2x4 base would help prevent that, but it did visibly push into the ground a bit. Im sure my data is a bit low due to that. I plan to make some kind of more rigid base in the future.
The area under the curve, using a trapezoidal riemann sum, is 5108. This is calculated by summing A[n] = Δt*(x[n]+x[n+1])/2 for n = 1...N-1 (Δt is the time step size, so 1/80s).
This was a very cool video! Can’t wait to see some more tests! Could you maybe test out all the motors and nozzles in one shot? Load up all the casings you have?
I will probably end up doing a compilation video of the various motor tests once I do enough testing combinations. It would be an insane amount of work to mix and test several propellant combos and motor combos for one video. I might do a simplified version though comparing a few types of propellant in the same motor casing with the same nozzle.
It is not NASA who cast the motor segments for the shuttle boosters. It was Morton Thiokol (later ATK, then Orbital ATK, now Northrop Grumman Innovation Systems). I know this because I interned there.
Yep NASA doesn't cast rocket motors. There were a few other's out there who cast rockets and tried to get the contract for those boosters... like Thiokol's old competitor Hercules (who was later bought by Thiokol/ATK)
@@stoneworld7556 Yep, Hercules cast the motors for the Titan III, and Titan IV rockets back in the day. That plant had over 6000 employees working and they were in full production. In fact, that is where I was, I just know so much about rocketry that I knew who really made the shuttle boosters.
Great video and rocket motor testing! I'll admit that I know next to nothing about what you are doing, but I'm learning a little bit more with every video, thanks!
after watching some of your vids the term lubing your shaft definitely has more than one meaning!! Birchwood Casey choke tube lube might be better for the threads, seeing how it's made for shotgun choke tubes. they tend to take high pressure and heat in extended firing sessions at the range, i've had pretty good experience with it! do you think the slight overheat may have sped up the burn rate any? i expected a bit longer burn for it being that sized motor.
ElementalMaker Very much so! Can’t wait to see the results with the smaller nozzle! Hey, along with different nozzle sizes, have you given any thought to trying different shapes? I could be wrong, but I think a flat taper is supposed to work pretty well.
You should get ahold of some MACOR! It's a machineable ceramic. Could be just the ticket to avoid eroding graphite nozzles. Should handle higher pressures as well for lower nozzle dias.
I use paraffin wax for my spindles. And you can put 2 to 3% of powdered graphit in your grog or bentonite clay. I use a bentonite powder, clay litter, and graphite in a mix for my nozzle and bulkhead. That's a good idea tho
Sweet what would it take to make a longer burn? A BIGGER engine lets find out. Because I'm no rocket engineer either so lets find out. ....Great video keep them comming.
Making it longer burning at the same specific impulse is not really possible using the same ingredients. Its kinda one or the other. But removing the core or narrowing the core bore size will all slow it down making a longer burn but it will also drastically affect or reduce the thrust at the same time.
To make the propellant burn longer would require changing the ratios, or adding a burn retarder such as baking soda in a small percentage. The issue then is your max thrust is reduced. So your essentially trading reduced max thrust for a longer burn. Of course there are more advanced propellants out there, such AP composite, which simply has a shit-ton more energy per gram than sugar propellant, so you can both create higher thrust and longer burns.
@@kwhp1507 With the same propellant, core and nozzle as well? No, it will increase the thrust/pressure and decrease the burn time. Increasing only the propellant length to get increased burn time only works with an end burn motor.
Looking at the image at 11:47 the ideal square pulse area is 1.3*5417 = 7042 gram*second. However, I estimate there is a loss of about 30% of that area by eyeball, so the area under the curve is a bit under 5000 gram*second, or about 50 N*s for your impulse. This is just a rough eyeball, but should be good to within about 5%.
Wow...Congratulations ! Excellent video, well explained. Especially the terms most your viewers probably are familiar with but I wasn't. Thanks for sharing the experience, loved it...Peace
To get your total impulse a quick way would be to take the average of all your thrust data points and multiply it by the duration of the burn. Might have to convert thrust data to a proper force unit of Newtons though.
I think you want "total impulse" which is the integral of force and time (area under your curve.) Each row in your SS is a "slice" of time - say 0.001 seconds. So, each row needs to be converted to Newtons (x 0.00981N/g) then multiplied by the time slice (0.001S) and then you SUM() that up.
Why not use a icing bag or large syringe to fill it or even better pile it in upside dow without rod init then push rod through it with it flush to the table it will compact better.
in the future it would be interesting to know more data on the motors, like the mass before and after the burn so we can know the percentage of propellant burnt.
This is the only channel I find myself referring to repeatedly to. Like school texts. My test stand is complete and I just graphed an old Estes A8-3. I drilled holes in the pvc and hold the motor in with those squishy ear plugs. 3 of them hold it through the ejection charge. I added an igniter continuity LED and a 1.8" Display (invisible in full sunlight) Might need a piezo buzzer.... Long comment to bump RUclips Algos.
@@ElementalMaker I was surprised. I bought these about 10 years ago. Thought they would be trash. (But I live in the Phoenix, AZ area) Even the igniters still work! with 9ish volts.
Just add your thrust from start to end = 408.6 (in kgs). Multiply by your sampling rate (0.0125 sec) = 5.108 Kg-sec. Now multiply by gravity (9.81m/s^2)= 50.11 N - s....Or if you divide by 4.448 you get 11.27 lbf-s... pretty good for this tiny grain :)
I don't know how to get the area under a curve for in Excel either, but I know a very old school method. Weigh and measure the paper to get weight/area. Then cut the curve out and weigh that. Welcome to 1940's rocketry!
You should have a cover over the Arduino and a warming box for the laptop so it stays live for you. Also what about using flash paper instead of black powder? I would think that might be a little bit cleaner.
You could photocopy the thrust time curve, then trace the curve on a flat plate of aluminum, cut the plate to the shape of the tracing then weigh the cut out of the plate. The weight is then proportional to the area of the curve. To estimate the total impulse make a rectangle out of this same aluminum plate, call one side “time” and the other “thrust” and multiple the length times the width, this area is the “standard” total impulse of the known area. The unknown is then the ratio of the weight of the unknown curve to the weight of the standard rectangular plate. This is the “Galileo” method of integration. A faster method of the “Galileo” method is the use a length of fishing line and make a loop corresponding the total irregular close loop of thrust versus time. Then do the same with another piece of fishing line for the “standard rectangle” then the ratio of the length of unknown curved loop, to the length of the loop enclosing the standard rectangle is the total impulse of the test motor. Of course the curve “y -axis” and curve “x-axis” must be in regular units between runs (pick a total curve height greater than the expected thrust) and fix the ordinate scale. You can’t let the spreadsheet autoscale, you must use the same total height of the y-axis be fixed between runs .
have you tried to do multiple different ones like one of the fast burn (with the iron oxides) and the last one is a normal so that it has a lot of thrust and then it goes into the normal for long burn and yada yada and then have the burst charge to make a awesome rocket. should do a video of making a rocket and letting it fly
From the timepoints of your measurement you can calculate a delta t between one point and the one before, a simple subtraction. Then you multiply the delta t to each of your values of force. You said, that you are using grams as unit. One gram is 0.00981 N. For the delta t I calculated 0.0125 s. When you multiply the force with the delta t, you get power in the unit of Ns. Then you sum up all the Ns. With your provided data I resulted with 49,191 Ns, what makes this motor a F-type.
Trapezoidal integration of the excel data should be easy. Mathematically you average datapoint 1 and 2, multiply the time between samples, repeat for 2 and 3, etc... and add them all up. In excel you should get the same results by averaging all of the numbers and multiplying by length of time between the first and last datapoint.
Nice experiment and great maker build. Have you considered trying Matlab or Freemat for analyzing your data? I think there might be something there you could use.
Liquid fuel is pretty tough to do at the Amateur scale, especially on a very limited budget. I will be doing some hybrid motors soon though! Maybe liquid fueled someday
@@ElementalMaker Hybrids are not extremely difficult, if you use nitrous oxide as your oxidizer. The hardest part is avoiding an oscillating burn. Liquid fuels are more problematic, since you have to control two liquid pressures to get a stable burn.
I'm a big fan of your channel! How do you calculate the diameter of the core rod for optimum thrust without blowing up the grain/engine? What percentage of the OD on the engine grain is the diameter of the core hole in the engine?? 25%?? Thanks
Hey man, I got a challenge for you: Make a rocket that explodes in the air, and the bang has to be heard 10 miles away. Let me explain, my grandpa challenged it to me last New Year's eve, but frankly I have no idea. That's why I turn to the professional. I hope you can help me. Anyways, greetings from Spain!
why not rcandy? there was a software that we used in the past to calculate the grain size, core size and nozzle size and shape calculated by the required performance... i dont remember the name but i will search for it when i have time...
@@sethmorton8539 from fast search thru my external hdd i found this links (sorry had no time to check more what is what): www.grc.nasa.gov/www/k-12/rocket/Downloads/index.htm www.spacecad.com/ www.space-rockets.com/cgcalc.html www.microsoft.com/en-mk/p/high-power-rocket-nozzle-designer/9nblggh68gfz?rtc=1&activetab=pivot:overviewtab www.nakka-rocketry.net/softw.html burnsim.com/ www.nakka-rocketry.net/design1.html www.nakka-rocketry.net/th_grain.html i couldn't find exactly the link i was looking for with fast search, but i hope some of those links will lead you to the exact software... later i might search again for it more thoroughly... i remember it was a calculation based on the max pressure you want in the motor chamber or something like that...
WooHoo! So, what is the limiting factor for the size of the grain? Could you make one twice as long for twice the burn duration, as opposed to two stages of the same length? Is the limiting factor nozzle erosion?
My hearing sucks--who provided the motor casing? And do you have a video about that thrust measurement setup? I'm Patreaoning, not a total parasite on your excellent channel, this is great stuff.
Hey Kei, thank you for your support! The motor casing and nozzle parts came from Foley Defense of West Virginia. I do have a video on the thrust measurement stand. I will find it and link it in another comment after this one.
Such a welcome sight your video is. Takes my mind off the fact that my wife has fallen out of love with me. Why i didnt want to get married in the first place.
Hey Josh I'm so sorry to hear that. I hope you and her can reconcile things and grow close again. I'm not much of a counseling kind of guy, but just doing something like a date night once a week, every Thursday night in my case, no cell phones allowed, has kept my wife and I close. Just a thought that has helped us. If you ever need an ear to vent to just drop a comment.
Why not heat the side of the chamber so that it melts and settles easily ? And also can u do a video on different oxiders? Like I used patassium permanganate instead of potassium nitrate to make gun powder(kinda worked) research the different types of oxiders
Have you ever used a octo-star core rather than that smooth cylinder? How much did overcooking the propellant effect it's burn and thrust? Overall very nice.
I haven't yet but plan to in the future. That core geometry gives an incredible thrust curve. The overcooking likely decreased performance very mildly, since it was just barely caramelized. I will have to repeat the test with a fresh grain to quantify any difference.
For a moment I thought I was watching the AvE channel. Sound just like him.
I really wish more people knew about your channel
You and me both! LOL
@@ElementalMaker question why did the propellant go so fast
I found him exclusively because some other RUclipsr copied his video and he called such RUclipsr out on the comments. So I'd say the algorithm isn't helping a lot...
That's just the nature of this particular propellant. Its very fast burning stuff!
Maybe you should try 3lb black powder!
I'm commenting because yt promotes content that gets comments and I want your channel to succeed! I'm in school studying engineering right now and it helps so much to see these concepts in action.
I truly appreciate you commenting! I hope you are enjoying the content, and continued good luck at school!
You may consider using one of those squishy ear protection devices to plug the nozzle... This will hold the e-match in place and secure any loose black powder, when in normal launch configuration orientation.
Damn that's genius!
Great to see my cheery friend again.What can I say,"Bigger is Better" eh. Woohoo bud. Bring on the 6.3 my friend !
The LASQAD (loose and sloppy, quick and dirty) method for finding the area under the curve, insert the image of your graph into a Fusion360 CAD canvas, scale the dimensions and select the find area command.
The simplest way to integrate over a dataset in excel, I think, would be to sum up all your data points, and then multiply by the length of the timestep.
Edit: Doing that with the data you linked between the marked start and end points gives me ~50.1 Newton-seconds of impulse, so the motor would be a class F, and your specific impulse is 68 seconds (an exhaust velocity of 668 m/s).
I've just done the same (worked out average thrust from data points, although changed start and end points you labelled)
So can back up Zuthal's Maths
Total Impulse = 51.61 Ns
Isp = 70.23 Sec
Eff Exhaust Vel = 688m/s
A smaller nozzle diameter/high chamber pressure should yield higher exhaust velocity and efficiency
Hears, "TODAY!..." Expects, "A Treat Especial!"
Is this a doppleganger or twin?
I keep hearing this classic rock song in my head. MOTOR GRAIN!!!
Hey,
I just wanted to let you know that you inspired me to start making videos. Your videos are great btw, and this rocketry series is awesome!
That casing/nozzle setup is absolutely farking awesome. The test rig you built is super cool too. Great vid, that was super interesting. Loved it.
Thanks Thor!
It seems like a lot of people are just calculating the total impulse, which I agree is around 50 N-s. This isn't the full story however, specific impulse or Isp is better way to gauge the performance of a rocket.
Isp = I/(m*g0), I being the total impulse, m being the propellant mass, and g0 being the local acceleration of gravity. propellant mass is 75 g (0.075 kg), g0 is 9.8 m/s^2, and I is 50 N-s
50/(0.075*9.8) = 68 s. Pretty good Isp for a sugar motor.
Typical estes motors can range from 50-80 s. The space shuttle SRBs were around 250s.
A cool program to check out, ProPep 3 uses thermochemical calculations to give you the optimum Isp for a particular propellant mixture. It also spits out other parameters that can help calculate the ideal nozzle expansion ratio. There are hundreds of chemicals to choose from it really helps when designing hobby motors.
www.rimworld.com/loggerusb/propep3/intro.html
how'D you get the Impulse/I
@@princemiro7241 Total impulse is area under the Impulse curve
Andrew Mitchell you just need to multiply each data point by delta t and add them up. This will give you a good approximation.
Beautifully done, my friend. Can't wait till the next test! Keep plugging along!
I've done some calculations in R and seems like the area under that curve is 5107.915 g-s with absolute error < 0.55. The error (which is really small) is due to the adaptive quadrature method used for evaluating the area. It could be a little bit higher because of the Hermite spline interpolation done on the data, but still I don't think that could be problematic at all! The area is calculated on the raw data given, I don't know if there was some scaling to do beforehand
So the result comes out to be roughly 50 N-s
That is most certainly not the Isp.
Yeah I calculated 5096 g*s, in Excel. I just did rough area calc by taking difference in time data points * thrust data point and then summing them all up. riemann sum.
Yes the error is small. I think you're overlooking something. Don't you?
@@PaulHollandWheels Being the data without any error, the only error is in the evaluation of the area under the points which is given directly by the function in R! The resulting plot is very well-behaved so I would expect the error on the area to be small
@@Wompylulz I was just giving you a hard time . I'm in awe of people like you I really have no idea and it's right or wrong I don't even know for sure what the equation is I know it pretty cool to be able to do that though😉
you should add a really small amount of copper oxide (or copper dust) and get a green jet.
Copper oxide works great for color in AP based motors, but on nitrate-sugar based motors there is just smoke :(. It does increase the burn rate a bit though! I will be using copper oxide in some future videos on AP motors.
@@ElementalMaker As you probably know, it is because the particular 'ammonium-based solid oxygen' you are referring to has Cl in it and can therefore act as a chlorine donor.
@@ElementalMaker also hybrid motors are pretty cool *wink wink*
@@hiddencow3272 hybrid motors are on the way 👍
A bp acetone slurry in the core ensures that everything gets lit instantaneously. The powder doesn’t do near as good of a job!
brilliant
Area under curve would be total impulse(just a sum of all the data points divided by the number of samples per second). To get specific impulse you then have to divide by weight of the propellant burned during that period.
Taking 1.2875s of data, the total impulse was 49.89N-sec, for an average thrust of 38.75N. You could call it an F39. Thanks for sharing the data!
~5107g g-s, so about 50 N-s. Happy to send you a spreadsheet.
I got a hair lower using excel but not far off. If rounded up what I get comes to 5kg so yeah not bad for a sugar motor with too big a nozzle. He's into midpower with an F motor.
I have to disagree with this value. Just by "eye-balling" a close up of your chart...ie: length of burn ≈ 1.15 s and the MEP (mean effective pressure) appears to be ≈ 2500 g so the product of these two would be the Impulse (area under curve) ≈ 3000 gram-sec or about 30 N-s. The MEP can be judged fairly accurately by eye, if you imagine a horizontal line that would split the rocket engine's graph in half area-wise. I estimated this line to be at 2500 g.
core shape makes a difference, a lot of the solid boosters are 8 prong star shaped
There always that side of me that wants to see a failure but not so much on this awesome setup.
I second that.
I can't say I disagree! Although I would hate to see my thrust stand and electronics go up in smoke... Still though LOL
Fuk the pair of ye, I wanna see an explosion🙌😂
Wait I noticed something we watch the same videos!🙂
wrong x9
For the area under the curve, just sum all the data from START to END, and multiply the result by the timestep Δt (time between two consecutive measurements).
A = ~5098 [grams-force seconds] = ~50.01 Newton seconds
That's because you're building the area from little rectangles.
Every rectangle has height=value in grams-force and width = Δt.
=> Area of the rectangle is Ar = height * width = value * Δt
So we just sum all the areas:
Total Area A = ∑i (Ar_i) = ∑i (value_i * Δt)
But since Δt is the same across all rectangles we can simplify that to:
A = Δt * ∑i (value_i)
Wow I didn't think how simply I could have calculated it! Thanks for shining some light into a dim section of my brain 👍💡
@@ElementalMaker
Yeah, that's why I like discrete math stuff xD
I've also made a spreadsheet with graphs and other cool numbers.
Maybe it could save you a little time, so you may want to check it out: goo.gl/n1HqdH
Thank you for the good content!
@@ElementalMaker Use rectangles where the curve goes through the center top of the rectangle. This approximates better because it takes the somewhat triangular section of the segments into consideration.
You can use different width rectangles - as long as you also use the appropriate time for each segment. It is even possible to use horizontal segments, or a combination of the two.
Excellent video and beautiful test!! Just a recommendation, for best results during the measurement, you could put the test device in a rigid surface, because I suspect that the grass absorbs part of the rocket engine energy 8:32 and consequently you will measure less thrust (or a different curve). It would be curious to see if there is any difference. Your channel is awesome! Regards.
Thank you! Yeah I was hoping the 2x4 base would help prevent that, but it did visibly push into the ground a bit. Im sure my data is a bit low due to that. I plan to make some kind of more rigid base in the future.
been wee-aitin for it! BLOW me away. side note, if you add an ad at the end ill "watch it"
Truly appreciate it Bob!
The area under the curve, using a trapezoidal riemann sum, is 5108. This is calculated by summing A[n] = Δt*(x[n]+x[n+1])/2 for n = 1...N-1 (Δt is the time step size, so 1/80s).
The guys at Morty Thikol did the SRB motors and stack for the Shuttle. Interesting how fast the motor peaks.
This was a very cool video! Can’t wait to see some more tests! Could you maybe test out all the motors and nozzles in one shot? Load up all the casings you have?
I will probably end up doing a compilation video of the various motor tests once I do enough testing combinations. It would be an insane amount of work to mix and test several propellant combos and motor combos for one video. I might do a simplified version though comparing a few types of propellant in the same motor casing with the same nozzle.
It is not NASA who cast the motor segments for the shuttle boosters. It was Morton Thiokol (later ATK, then Orbital ATK, now Northrop Grumman Innovation Systems). I know this because I interned there.
Yep NASA doesn't cast rocket motors. There were a few other's out there who cast rockets and tried to get the contract for those boosters... like Thiokol's old competitor Hercules (who was later bought by Thiokol/ATK)
@@stoneworld7556 Yep, Hercules cast the motors for the Titan III, and Titan IV rockets back in the day. That plant had over 6000 employees working and they were in full production. In fact, that is where I was, I just know so much about rocketry that I knew who really made the shuttle boosters.
nice motor , nozzle and great cooking :) .. looking forward to 6.3 mill .. awesome ..
Great video and rocket motor testing!
I'll admit that I know next to nothing about what you are doing, but I'm learning a little bit more with every video, thanks!
after watching some of your vids the term lubing your shaft definitely has more than one meaning!! Birchwood Casey choke tube lube might be better for the threads, seeing how it's made for shotgun choke tubes. they tend to take high pressure and heat in extended firing sessions at the range, i've had pretty good experience with it! do you think the slight overheat may have sped up the burn rate any? i expected a bit longer burn for it being that sized motor.
"A double entendre!", he ejaculated.
I’ve been waiting for this video!! I’m happy now! 😊
Hope you enjoyed!
ElementalMaker Very much so! Can’t wait to see the results with the smaller nozzle! Hey, along with different nozzle sizes, have you given any thought to trying different shapes? I could be wrong, but I think a flat taper is supposed to work pretty well.
Awesome job! Can't wait for the next one...
You should get ahold of some MACOR!
It's a machineable ceramic. Could be just the ticket to avoid eroding graphite nozzles. Should handle higher pressures as well for lower nozzle dias.
I'd be interested to see the effects of fine Al powder addition on performance, though I'm not sure how safe it would be during the "cooking" step.
Awesome video man! Anyone ever said you sound like Negan from TWD? Because you do. (Not a bad thing)
I've heard it quite a few times! LOL
Hey congrats on your first burn with that grain! I've been experimenting with KNSU cold packing rocket motors and they are a lot of fun!
Thanks Bud
That was a really cool video.
Can't wait to see more testing.
Super cool.
:D
I use paraffin wax for my spindles. And you can put 2 to 3% of powdered graphit in your grog or bentonite clay. I use a bentonite powder, clay litter, and graphite in a mix for my nozzle and bulkhead. That's a good idea tho
It was nice to see your likes go from 1999 to 2K. It was me.
Thank you!
Not to be pedantic, but please put units on your excel sheet, it would make the math much easier (as in I wouldn't have to read and guess as much)
Glad I found you. Great info on this channel.
Sweet what would it take to make a longer burn? A BIGGER engine lets find out. Because I'm no rocket engineer either so lets find out. ....Great video keep them comming.
Making it longer burning at the same specific impulse is not really possible using the same ingredients. Its kinda one or the other.
But removing the core or narrowing the core bore size will all slow it down making a longer burn but it will also drastically affect or reduce the thrust at the same time.
To make the propellant burn longer would require changing the ratios, or adding a burn retarder such as baking soda in a small percentage. The issue then is your max thrust is reduced. So your essentially trading reduced max thrust for a longer burn. Of course there are more advanced propellants out there, such AP composite, which simply has a shit-ton more energy per gram than sugar propellant, so you can both create higher thrust and longer burns.
@@ElementalMaker Or making motor with larger diameter
Will a longer motor case of the same diameter increase the burn time proportionately?
@@kwhp1507 With the same propellant, core and nozzle as well? No, it will increase the thrust/pressure and decrease the burn time.
Increasing only the propellant length to get increased burn time only works with an end burn motor.
Milk of Magnesia is pretty good, cheap anti-seize. Good power!
Looking at the image at 11:47 the ideal square pulse area is 1.3*5417 = 7042 gram*second. However, I estimate there is a loss of about 30% of that area by eyeball, so the area under the curve is a bit under 5000 gram*second, or about 50 N*s for your impulse.
This is just a rough eyeball, but should be good to within about 5%.
Very good estimation! The most exact answer I've seen so far was 49.795 or something along those lines 👍
Wow...Congratulations ! Excellent video, well explained. Especially the terms most your viewers probably are familiar with but I wasn't. Thanks for sharing the experience, loved it...Peace
Thanks Grant! Glad you enjoyed!
If you want to integrate that you just need to multiply each data point by delta t and add them up.
To get your total impulse a quick way would be to take the average of all your thrust data points and multiply it by the duration of the burn. Might have to convert thrust data to a proper force unit of Newtons though.
I think you want "total impulse" which is the integral of force and time (area under your curve.) Each row in your SS is a "slice" of time - say 0.001 seconds. So, each row needs to be converted to Newtons (x 0.00981N/g) then multiplied by the time slice (0.001S) and then you SUM() that up.
Why not use a icing bag or large syringe to fill it or even better pile it in upside dow without rod init then push rod through it with it flush to the table it will compact better.
Would be interesting to see you try and maximize the burn time instead of thrust. Good video.
IIRC you can add corn starch to lengthen the burn
It’s so cool to see this crap actually work after so long of working on it great job man hopefully you can get something in the air soon
Thanks! Hope so!
in the future it would be interesting to know more data on the motors, like the mass before and after the burn so we can know the percentage of propellant burnt.
This is the only channel I find myself referring to repeatedly to. Like school texts.
My test stand is complete and I just graphed an old Estes A8-3.
I drilled holes in the pvc and hold the motor in with those squishy ear plugs. 3 of them hold it through the ejection charge.
I added an igniter continuity LED and a 1.8" Display (invisible in full sunlight) Might need a piezo buzzer....
Long comment to bump RUclips Algos.
Thanks for the great comment 👍. What kind of thrust did you get from the A8-3?
@@ElementalMaker 968g peak. Wish I could post pictures... Just posted the graph on twitter: _Mycroftxxx
@@_mycroftxxxadamselene922 wow pretty impressive thrust!
@@ElementalMaker I was surprised. I bought these about 10 years ago. Thought they would be trash. (But I live in the Phoenix, AZ area) Even the igniters still work! with 9ish volts.
@@_mycroftxxxadamselene922 black powder doesn't go bad as long as it's kept dry! Graph looked beautiful. Great data 👍
Weigh the cut out curve and weight a square inch of the same paper and you can compute the area
I use to make and fly rockets ! 3" x9" slugs
Nice!
If an AP/aluminum fuel, sounds like about a J for Isp.
Are these casting molds available to buy and if so, where?
If you haven't yet, you could change to a more powerful graphing software. For midrange stuff and making very pretty plots, I recommend Kaleidagraph
Awesome setup
Great video! I love rockets.
To anyone else watching. The motor Dynometer works very well. Very sensitive. It will detect the pressure of a fart.
I farted by mine and destroyed the smaller load cell. RIP little buddy.
Just add your thrust from start to end = 408.6
(in kgs). Multiply by your sampling rate (0.0125 sec) = 5.108
Kg-sec. Now multiply by gravity (9.81m/s^2)= 50.11 N - s....Or if you divide by 4.448 you get 11.27 lbf-s... pretty good for this tiny grain :)
I don't know how to get the area under a curve for in Excel either, but I know a very old school method. Weigh and measure the paper to get weight/area. Then cut the curve out and weigh that.
Welcome to 1940's rocketry!
Wow, that's brilliant!
Makes me wonder if a suppressor body (no baffles, or baffles removed) could be used as a high capacity engine case and nozzle.
The suppressor case doesn't have a nozzle, just a hole, so it would basically be a cylindrical pipe section...
Always remember "keep your little rocket in a vice"
That's a spicy-a marshmallow!
You should have a cover over the Arduino and a warming box for the laptop so it stays live for you.
Also what about using flash paper instead of black powder? I would think that might be a little bit cleaner.
You could photocopy the thrust time curve, then trace the curve on a flat plate of aluminum, cut the plate to the shape of the tracing then weigh the cut out of the plate. The weight is then proportional to the area of the curve. To estimate the total impulse make a rectangle out of this same aluminum plate, call one side “time” and the other “thrust” and multiple the length times the width, this area is the “standard” total impulse of the known area. The unknown is then the ratio of the weight of the unknown curve to the weight of the standard rectangular plate. This is the “Galileo” method of integration. A faster method of the “Galileo” method is the use a length of fishing line and make a loop corresponding the total irregular close loop of thrust versus time. Then do the same with another piece of fishing line for the “standard rectangle” then the ratio of the length of unknown curved loop, to the length of the loop enclosing the standard rectangle is the total impulse of the test motor. Of course the curve “y -axis” and curve “x-axis” must be in regular units between runs (pick a total curve height greater than the expected thrust) and fix the ordinate scale. You can’t let the spreadsheet autoscale, you must use the same total height of the y-axis be fixed between runs .
Imagine this, but with a teeeny bit of iron oxide....would love to try that myself
I'll be testing that soon 👍
Really nice video as always👍 keep up the good work
Will you ever build rockets that fly?
Thank you! I definitely will get something in the air soon!
Keep up the good work. Love the vid's. Approximate power of motor = (RMS of Peak) x time. As it was a pretty smooth "bell curve."
Have you ever replaced the water in your hho generator? By the way I built a HHO generator using your design but with 10 cups.
I've replaced it a couple times so far. And awesome! Hope its working a treat for you!
Nice test
have you tried to do multiple different ones like one of the fast burn (with the iron oxides) and the last one is a normal so that it has a lot of thrust and then it goes into the normal for long burn and yada yada and then have the burst charge to make a awesome rocket. should do a video of making a rocket and letting it fly
From the timepoints of your measurement you can calculate a delta t between one point and the one before, a simple subtraction. Then you multiply the delta t to each of your values of force. You said, that you are using grams as unit. One gram is 0.00981 N. For the delta t I calculated 0.0125 s. When you multiply the force with the delta t, you get power in the unit of Ns. Then you sum up all the Ns. With your provided data I resulted with 49,191 Ns, what makes this motor a F-type.
Thanks so much Sebastian!
oh i see you got inspired by the yellow thing from the last video
That I sure did! Nearly there! LOL
Trapezoidal integration of the excel data should be easy. Mathematically you average datapoint 1 and 2, multiply the time between samples, repeat for 2 and 3, etc... and add them all up. In excel you should get the same results by averaging all of the numbers and multiplying by length of time between the first and last datapoint.
Graphite is king.
Damn Im jealous. no more cardboard and kitty litter for you...
Haven't seen you in a while. Glad you're good
Nice experiment and great maker build. Have you considered trying Matlab or Freemat for analyzing your data? I think there might be something there you could use.
Ill have to take a look at them! I cringe hearing Matlab after my college experiences with it LOL but that was some time ago.
Very pretty.
Hey alright! Awesome. Still haven't used my rocket motor Dynometer. To cold here.
Sum up all your data points and multiply by the time interval between samples, yes?
can you tell us how you record all that data and what are you using with arduino to make all this ?
he did a video on that like a couple weeks ago, check the channel, its somewhere recent
Do you have a video where you fly the motor? Would like to see that.
have you ever thought about trying to make liquid fueled rockets? great work btw!
Liquid fuel is pretty tough to do at the Amateur scale, especially on a very limited budget. I will be doing some hybrid motors soon though! Maybe liquid fueled someday
@@ElementalMaker Hybrids are not extremely difficult, if you use nitrous oxide as your oxidizer. The hardest part is avoiding an oscillating burn.
Liquid fuels are more problematic, since you have to control two liquid pressures to get a stable burn.
You should make and sell igniters to make money. I don't have time to make them.
I'm a big fan of your channel! How do you calculate the diameter of the core rod for optimum thrust without blowing up the grain/engine? What percentage of the OD on the engine grain is the diameter of the core hole in the engine?? 25%?? Thanks
Hey man, I got a challenge for you: Make a rocket that explodes in the air, and the bang has to be heard 10 miles away.
Let me explain, my grandpa challenged it to me last New Year's eve, but frankly I have no idea. That's why I turn to the professional. I hope you can help me.
Anyways, greetings from Spain!
why not rcandy? there was a software that we used in the past to calculate the grain size, core size and nozzle size and shape calculated by the required performance... i dont remember the name but i will search for it when i have time...
IamIUareU if you find it let me onow
@@sethmorton8539 from fast search thru my external hdd i found this links (sorry had no time to check more what is what):
www.grc.nasa.gov/www/k-12/rocket/Downloads/index.htm
www.spacecad.com/
www.space-rockets.com/cgcalc.html
www.microsoft.com/en-mk/p/high-power-rocket-nozzle-designer/9nblggh68gfz?rtc=1&activetab=pivot:overviewtab
www.nakka-rocketry.net/softw.html
burnsim.com/
www.nakka-rocketry.net/design1.html
www.nakka-rocketry.net/th_grain.html
i couldn't find exactly the link i was looking for with fast search, but i hope some of those links will lead you to the exact software... later i might search again for it more thoroughly... i remember it was a calculation based on the max pressure you want in the motor chamber or something like that...
Hello! Great video :) The proportions of sorbitol and potassium based oxygen which you used on the mixture are molar or massic?
WooHoo! So, what is the limiting factor for the size of the grain? Could you make one twice as long for twice the burn duration, as opposed to two stages of the same length?
Is the limiting factor nozzle erosion?
I demand daily vlogs
My hearing sucks--who provided the motor casing? And do you have a video about that thrust measurement setup? I'm Patreaoning, not a total parasite on your excellent channel, this is great stuff.
Hey Kei, thank you for your support! The motor casing and nozzle parts came from Foley Defense of West Virginia. I do have a video on the thrust measurement stand. I will find it and link it in another comment after this one.
Here's the arduino test stand video ruclips.net/video/-yq1EmTkBCs/видео.html
Such a welcome sight your video is. Takes my mind off the fact that my wife has fallen out of love with me. Why i didnt want to get married in the first place.
Hey Josh I'm so sorry to hear that. I hope you and her can reconcile things and grow close again. I'm not much of a counseling kind of guy, but just doing something like a date night once a week, every Thursday night in my case, no cell phones allowed, has kept my wife and I close. Just a thought that has helped us. If you ever need an ear to vent to just drop a comment.
Why not heat the side of the chamber so that it melts and settles easily ? And also can u do a video on different oxiders? Like I used patassium permanganate instead of potassium nitrate to make gun powder(kinda worked) research the different types of oxiders
Have you ever used a octo-star core rather than that smooth cylinder?
How much did overcooking the propellant effect it's burn and thrust?
Overall very nice.
I haven't yet but plan to in the future. That core geometry gives an incredible thrust curve. The overcooking likely decreased performance very mildly, since it was just barely caramelized. I will have to repeat the test with a fresh grain to quantify any difference.