APCP Rocket Motor Test with Data. DIY Composite Rocket Motors
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- čas přidán 16. 01. 2020
- Round 3 of testing the APCP motor and we finally get some data!
-Help EM build an airframe and avionics for a real launch! / elementalmaker
-Please save this link as your amazon homepage, so when you shop its supports the channel: goo.gl/x1ehvA
Make sure you check out Foley Defense since they were generous enough to send us this great motor! I have confirmed with the owner that they have these motor kits available for purchase, so email Foley Defense to buy yourself a kit.
The above contains amazon affiliate links which earn the channel a small commission and help me to produce the videos. - Věda a technologie
2:18 Oh damn, you got a mach diamond there!
So same test meaning still over-expanded :)
I saw the diamonds!
Can't wait to see this thing with a tiny bit choked down nozzle for that sweet spot.
was exactly thinking about that.
Man I am still loving the rocket stuff. The shock diamonds or whatever they're called are sweet looking. Also random people reading this comment you should join the patreo so you can have early access to videos and be that annoying guy who leaves "first" comments.
I also still find it wild you found the random tab welder video I have. I was thinking about that randomly last night and what the odds were of that and how I made that video for the AvE subs then found you through AvE (suggested video on the side) then a few months later you comment on that video. Tiny world here on youtube.
Thd Shock diamonds produced by the Space Shuttle were particularly stunning, with their conical shape and all that power.
Oh, man... I still love these shock diamonds... Keep it up, you've got amazing content! (In your videos, you do exactly, what i love doing in my backyard! ;D )
Haven't been back on this channel in a while and wow! APCP! So cool! Loved your sugar motors but I also was waiting to see you try APCP
I love this channel so much. It's totally me deep down inside. Thanks for keeping me on track. It's easy to get distracted by every day hassles. It's nice to be relieved 😊 by raw science
Hell yeah! Love the rocketry stuff on your channel. Can't wait to see bigger and thrustier engines ;)
And now you’re on a list! You were on a list before, but that was a different list.
Keep it up! W00t!
Its awesome to watch you work. It shows that anyone can create these projects with self education and work. Will love to see a larger motor lift off. Best wishes to you and your family.
Cant wait to see some of this in a rocket and not just a test on the pad. That will be awesome!
another beautiful burn, very cool to see the data
Love the rocket experiments!
@ElementalMaker Just subscribed to you on Patreon, my first ever. THIS is the type of content I have been searching/waiting for friend! I have a goal of reaching level 3 NAR cert at some point (i'd like in the next 10 years), and to be able to do it with 100% from scrap material (if that is allowed). Everything rocketry interests me so keep it coming!
awesomeness dude, now the next logical step is stacking 3 bates grains,
If you're having trouble finding Mann400 (check Grainger's,) you can wrap the mandrel with Teflon plumber's tape, then peel it out after the grain cures.
The ends of your grain failed to ignite, yielding a very progressive burn profile. Rough grain ends can be... problematic. To yield a more neutral thrust curve, you will want to promote a full Kn start. Cast your grains a bit too long, then trim to length, with both ends flat for a single grain motor, or very slightly concave for a multiple grain motor. And you don't want to "over-stuff" your case. You want tiny little gaps between the fwd closure, the grain, and the nozzle. To allow the ends to ignite.
BTW... I've been making this stuff for twenty years. In case you're wondering...
Awesome video
Seems like this might be a good candidate for a second stage motor
I have several spare gallons of of white urethane casting resin . It's low viscosity , like water and has 20 min pot life . I'm happy to share it with you and the correct mold release.
Again my friend, Great.
I know nothing about rockets but I know that this looks freaking cool. 👍
I do a fair amount of epoxy casting and my go to parting agent is paste wax. A bit of taper on the rod would help a bunch also
That was about as perfect as you can get. Love to see the AP cell & double displacement you used in making your O2 component of fuel? Pre made/ disposable motors are too expensive, making your own is only way to go.
OK; you got me, SOB.
Finally patreoning for a Beer O'Clock.
Which is oddly fitting since I always watch YT Friday night with a sh*t ton of beer and nicotine.
Thanks so much! Appreciate it bigtime! 👍
have you considered a star core at the top to increase your initial boost? tiz just a thought ;)
Could you maybe do a multi-stage motor where the launch stage is a sugar motor and the second stage is one of these?
That would be really awesome!
@@ElementalMaker it would, indeed
Just a conjecture, but perhaps the flame isn’t properly traveling down the barrel of the fuel and that’s why your seeing that reverse thrust curve. Putting the igniter deeper might solve the problem if that is the case
Got the igniter are far down in the core as possible. The thrust curve is characteristic of the core type. A star core would resolve the thrust curve, but is alot more complex to make.
@@ElementalMaker (edit: I now see you commented on one of the videos so you are aware of it.) I was going to suggest a star core. Anyway, you should check out this channel, KUNFU CHAN that seems to be someone in China making large HTPB rockets, some made with carbon fiber.. Not many views but the short videos are interesting. He shows his manufacturing setup and thrust tests. In one he launches a powerful rocket almost horizontal in a valley that was wild. link: czcams.com/channels/t2mQxTYdcAc63b7i-EGD3g.html
Also, to get better release you may want to look into making the central rod of your core mold out of either teflon or POM (polyoxymethylene, Delrin). Both are very slippery and nothing really adheres well to them. You can also 3d print POM.
You know these my favorites
That's a classic core-burner thrust profile. starts with a lower thrust and steadily increases as the surface area of the core increases.
Of course you could cast a star shaped core to increase initial surface area, but you'd have to make the appropriate spindle first (what do you mean, you don't have a cnc machine?!) and getting the spindle out of the grain could be a real pig unless you can get a release agent that actually works.
Try using a stubby (half-length ish) spindle, with quite a bit more taper to it. (the taper will help with the withdrawal process too!)
I'd guess she'd put out about 1/2 to 2/3 of the thrust your current motor will do to start with, then it'll drop off as it moves into the end-burning region. it'll burn for much longer though. which might be what you're after. If you can find the right compromise between core/end burning profiles you might have a winning combo.
If you want to change the shape of your thrust vs time, consider changing the ignition point inside motor. Igniting at the begin, middle or the end of the motor will yield different power curves.
2:16 - nice and very quick thrust vector control ;-)
To have a better thrust 'curve' I suggest you use a C-slot propellant shape. A simple hole in the center causes a progressive thrust profile.
The thrust curve is directly related to the burning area. Adding more grains of the same geometry will only increase total impulse and thrust (and pressure if you keep the nozzle constant). If you want more initial thrust you can change the internal shape to look like a star or something with more surface area than the circle.
Absolutely 👍
Awesome test. I'd like to point out that my comment on the last test video estimated the average thrust pretty well, albeit under-estimated the specific impulse by 35%. Any idea which this composite motor burned slower than the last one?
2 hours in, still haven't gotten a notification. Oh well.
Have to say, tho, your content is exceeded only by your delivery.
I'm starving for more elemental maker content please go daily or weekly at the least 😭
"Same shit, different toilet", Hahahahaha! That's why I love you, man!
It looks like a very well-behaved burn. In order to get the profile you're after, you will need to change the grain shape to one that generates it. This composition looks like a good candidate for profile experiments.
Soo going to be a air flame🔥🛩🔥
Data is beautiful! Instant thumbs up. Could the linear part of the thrust curve be ideal? You have the cylindrical combustion chamber growing in diameter as the burn goes on and the burn rate is increasing proportional to that since its a surface phenomenon. Maybe it just means you got a nice consistent fuel and with a constant throat diameter. And that initial spike is cool, i bet that's the igniter blowing blowing out. Thanks man!
yay more rocket stuff, Is it bad I want to see you put that thing on a rc car or plane?
Great video, but where is the link to Foley Defense ?
Have you tried teflon spray on the spindle?
Love what you do,but would like to see some skyward fails /successes
If you're looking to adjust that curve, you'll need to change the pattern of the burn area. You're currently using a circular pattern, if you want a higher initial thrust a Star pattern would give the result you're looking for.
Your absolutely correct. Been looking into machining some new casting molds
Been watching for awhile, I wish I could support, hopefully one day. :(
Your thrust curve looks correct given the grain arrangement and a single grain. Please start using liners of some sort to protect your nice casing. More bates grains will level it all out as will different core arrangements.
Thanks. And I am using a paper/cardboard liner. It's always intact after firing, so it's doing its job to protect the casing.
Did you do a Stock Shelf Motor as a Base line? Rockets are cool and all but I hadn't messed with
them enough to know much. DrPhu
What if you cast a small diameter sugar grain and then over-mold cast the full diameter composite propellant directly to the sugar grain? (I hope that makes sense.)
Any idea what the ideal chamber pressure is for your rocket? For a nozzle diameter of over 6mm, your nozzle end looks way under expanded, yet your'e still getting shock diamonds, a symptom of under expansion. I dont know anything about the kn curve of this propellant, but it seems that lowering the nozzle throat diameter might squeeze some more performance out of the motor.
Does that motor housing have a pressure-relief? I made something similar and it was fine for 20 or so firings until the pressure got too high one time and it became a pipe bomb. Full on detonation. Pressure got too high and we crossed DDT.
Question, would a lamilar flow nozzle improve the performance?
Also maybe 3 equally spaced sugar rocket boosters that then burn through and activate your slow burner there?
Can floor coating epoxy be used? Or fast drying expoxy? I can't seem to find HTPB in hardware stores. What is it used for?
Are those shock diamonds I see? If you made a hollow grain, esp. with some indentations in the inside surface, the initial burn rate would be faster than later, wouldn't it?
baking paper around the spindle?
what kind of rubber are you using for the fuel?
Is it possible to optimize the shape of the nozzle or do you need more data?
Loving the tests just say when you need it and what size im still thinking 7-10 ft dia and you will have the chute bonified pirate's turned out sweet
What about approximating the reverse of that curve by creating different ix ratios or possibly mixing 5, 10, and 20% of black powder in to your mix and then packing them in as 4 separate layers? You said the black powder burns fast so would that be a reliable way to provide that extra bit of thrust in the lift off at the start even if you just fill it up 70% with normal APCP with a little layer in the first 30% of the tube of black powder infused APCP? Or would this just be stupid and like making a pipe bomb?
You might want to consider using a star shaped grain center opening/spindle. That should result in a *MUCH* flatter thrust curve.
you should do a collaboration with Slow mo guys, you would get some really nice footage to go with your results
That would be absolutely awesome, but my channel is way too small for those guys. Maybe if I start building some much larger rocket motors... but then I'll need to move to the mojave desert, and I dont think the wife is into moving 2000 miles LOL
You didn't weigh the tube and liners before loading with propellant? What kind of shade tree hack are you?
(The kind of shade tree hack I subscribe to.)
Is this pyrogen igniter ?
What if the spindal was tapered like an ejection mold? That is h9w real srb's look inside anyway. Look at space shuttle srb cutaways
Why dont you try a 3 graib motor but with sugar in the first stage and APCP in the last stages
Are you adding any aluminum powder in your propellant composition?
Not yet, I'll be adding burn rate modifiers soon
Looked like a shorter burn time than your other motor experiments. What would give you a more even burn rate? Maybe a smaller nozzle would increase the internal chamber pressure to give you a more even burn rate on your graph.
Maybe instead of using a mold to form a core with more surface area you could try to machine it (maybe drilling 6 holes in hex mount or something like that) - that should provide a lot of starting thrust, although I have no clue on how dangerous would the machining be
dude I love your vids btw are you cousin of Ave? 🤣
Just a thought I had, could it make a difference which end of the motor ignition starts from?. ( That's probably a stupid question)
This isn’t a dumb question, starting near the opening you get a flame that climbs downward, but starting at the very bottom, you get it burning upward. From my experiences when I start at the bottom my motor explodes but staring at the top, I get a consistent thrust. This is because starting at the bottom provides a huge amount of thrust but for a short time as opposed to starting at the top which burns a little slower but longer.
Isn't it at 40grams or 50 that they become a dd?
You need to do a collaboration with JohnnyQ90 and Explosions&Fire2 to come up with some real whacky fuels and rocket motors haha haha
Do you plan to ride in this airframe? I would pay to see that
I find myself wondering if PVA would work as a mould release for your forming tooling. Spray it on the mandrel and let it dry and then pack away. PVA would disintegrate when you tried to remove the finished motor. Another thing that might help would be to machine a small taper of say .050" on the mandrel. Once the bond to the propellant was broken the mandrel would come out easily like a Morse taper. I also have to wonder what would happen if you used sodium silicate and CO2 on your propellant to harden it. Much easier to handle and less likely to fall apart while being consumed. If a motor core disintegrates as it burns it could force out partially burned propellant and negatively affect overall performance. I noted someone else had the same idea I had about using a sugar based propellant initially and then converting to the propellant shown here during the burn. The sugar would give a higher initial thrust but the second propellant would give you the longer burn and higher thrust pressures towards the end of the burn. Perhaps a 1/3-2/3 combination for a test would give some idea of whether it would be beneficial or not.
can u make a video of how to make the propellant
Check out my earlier rocket videos I show the process
Looks like the hiccup at the beginning of the graph was the hotwire diverting the nozzle pressure. That may have been just enough to stall/divert pressure, changing the results. I just wonder how much.
Just an observation.. I don't know jack about rockets. Yet!
Star pattern in the grain, but tricky to cast..
Any plans on the TATP pulse-motor?
How does that song go? "Peroxide and Acetone, a little dab'ill-do-ya..." Then something about putting your fingers into orbit.
TATP in a casing with an igniter in one end... congratulations, you've just invented the "pipe bomb".
have you looked at bps space's flight computer?
Love Bernard's channel and the rockets he's built. Seriously a genius guy. Can't really afford his flight computer right now, maybe in the future.
Get in contact with BPS Space Joe is awesome!!
I think you need another shape of hole in the core to get another thrust curve.
A cross in the core would probably be a good option. largest surface area at ignition decreasing when fuel burns up. Many rocketeers use flash cotton ignited by electronics to eject chute. usually half a gram is sufficient.
Adding a segment will not change the thrust curve much - you will still have a Bates core. To get high initial thrust with it tapering off, you need to burn from the outside in, or maybe get really fancy with the core shape.
In Australia a shit tonne is a measurement of weight. Lol!
Bro try parafin, beeswax, or white crayola crayon (titanium oxide pigment in parafin base) edit: lol I mean for mold release
Try pulling the spindle after an hour and letting it cure without it
The earlier test that you lost the results from looked a little better.
make one addition: add high voltage rings to make an ion engine
When are you going to put one of those rocket engines in actual rocket & send it up???
Looks like your trust is proportional to your burn area, if you where to pack your fuel in a cone shape instead of a cylinder (on the ID) you should see a more even burnrate. 15° should be a good starting number to try out.
You are correct. I am working on a couple ideas to establish greater initial thrust such as star cores etc. Cone would work but would sacrifice a large amount if propellant mass
@@ElementalMaker I agree that a star shape would be more efficient and there are losses to fuelmass when using a cone.
But I would argue that fuel given to useless thrust is not worth the mass.
But I will give a few other reasons to why I like the cone.
1. It's easy to make.
2. It's resistant to faults when moulding (stars are not in my experience)
3. It's easier to fine-tune the surface area and thereby the thrustprofile (usefull in the experiment fase even if you select another geometric form in the end)
4. The lowering of the thrust in the end of the burn makes for a wider window to fire a second stage whitout incurring stability issues. (Maybe not applicable to your plans, but be honest we all en up there in the end. If for no other reason than that the fuckups tend to be more exciting).
In any case god luck and let all rockets go far away from you (and other people to)
I swear I saw shock diamonds!
1) Your ISP is pretty poor for a composite motor - it should be in the range of 180 - 210. If I understood what you said, the maximum thrust is roughly the same as the propellant casing and fuel.
I think you need a much smaller diameter nozzle - or you need a casing that holds 3 or 4 grains using your smallest nozzle.
why don't you make the grain in 2 parts an inner shugger rocket part and an outer apcp part
That is one possible solution, but the route I'm going to go is to use a core shape with greater surface area, such as a star or cross shape.
@@ElementalMaker what about makeing multiple holes down the middle of the grain and igniteing it from the back
I can't afford to contribute money to your channel, but I would be more than happy to donate some time helping you design some of the various avionics and data loggers. I am currently going to school for that sort of thing and I would love to help out
Ok hear me out: 42 pound version of this strapped into 4 skateboards (one on each side of the cylinder, wheels out) and wings made of....something strong, maybe flex seal. I'm sure it would go at least 6 feet
at about 30+g's? :P
You should make sugar rockets with candy.
A caramel fuel grain lol
Aww... u mention 2 & 3 grain motors + sugar, I was hoping u weaponized the gummy bears. 😅
You need to get him to make you a full on De Laval nozzle to play with. Have I ever mentioned that October Sky is one of my all time favorite movies? :P For anyone that wants to know what I'm on about: en.wikipedia.org/wiki/De_Laval_nozzle I'd definitely try using fine graphite powder as a mold release.
I saw three diamonds... Maybe 2
To reverse your curve derivative, you'll wanna make your grain length a lot shorter
Star core for greater starting surface area is my planned solution.
@@ElementalMaker neat, should be a fun build
Might sound kind of stupid but maybe the simplest answer would be to use parchment paper
I used that same scale to sell drugs in my youth. Lol
I was under the impression that everyone that has these scales initially got it for drugs. I sure did.
My old scale I got to make sure my weed weighed what I was told has been used since for many batches of thermite and other similarly fun things
To be honest i bought mine for even weirder reasons. I used it to check if "match weighed" darts are actually match weighd.
Now i check my archery Stuff. Points, Nocks, Pins etc. to build the most consistent arrows i possibly can.
I got one over the summer for photo chemistry. (Had completely forgotten my reloading scale SMH; it measures down to 6mg.)
LOLOL 🤣