My Most POWERFUL Rocket Motor Yet! (Pushing the limits)

[@AeroPropulsions]

Please subscribe, comment, and like!

[@alexanderbraun9294]

Hey, copper o-rings might be a option to consider, keep up the great work ^^

[@AeroPropulsions]

Thank you for the input!

[@Rubencoheteriaexperimental]

Good job! Steel is not a good conductor of heat, so the heat that destroys the o-ring comes after the fuel has been consumed, always talking about short-term candy fuel (less than 2 seconds). The same thing happens with the o-ring in my engines, I have never had a leak and I always put in new ones (they are cheap). At minute 2:53 of the video I see the starter next to the engine, with which I estimate the length of the cable, at minute 4:13 you can see the starter placed on the engine, from what I see a lot of cable sticking out of it, this leads me to the conclusion that the starter is not inserted all the way into the engine, for the engine to start correctly the starter must reach all the way to the bottom. Greetings

[@AeroPropulsions]

Thanks for the insight! Steel’s low conductivity protects the O-ring during short burns, and replacing them often is smart. Great catch on the starter-it wasn't fully at the bottom. Will fix for the future tests!

[@rafaelguida2317]

Congrats on the new SN3!! Very hot and long burn! Im from Brazil and we are a university rocket team and we're taking a very similiar approach to design the nozzle and casing. I got a little curious, how exactly do you line the inside of the aluminium case? Also, this might be of your interest: I was researching thoroughly on rocket nozzle materials, material combinations etc and one REALLY interesting approach I have yet to test is making a similar nozzle to yours in aluminum but with external grooves for passive cooling. It could be easily turned on a lathe and I believe this would help on the heat buildup. To mitigate surface erosion and melting, the aluninum would have to be " hardcoat anodized " this is a somewhat common process where a very thick oxide layer is grown on the part, acting as essentially as an insulator ( since aluminum oxide / alunina is used for making fire bricks etc ) Thanks fot the great video!

[@AeroPropulsions]

I do not use a liner inside the aluminum casing. For the relatively short burn duration, the 2mm cardboard casing on the outside of the propellant grain provides sufficient insulation. Across all 11 tests conducted with SN1, SN2, and SN3, there have never been any issues with the casing melting or deforming. That's a smart approach, I will look into that. I never considered it before. My other aluminum nozzles didn’t hold up well; they eroded and melted away! You're welcome! Glad you enjoyed it!

[@rafaelguida2317]

@@AeroPropulsions that's really interesting to know!! Thanks for the much appreciated info! I have never tested/calculated/ simulated the idea I told you about but I think it has some potential for short burns. The oxide layer is typically really thin, so the radially simetric grooves would help dissipate any heat that eventually goes through the surface. The " gotcha " is that preferably only the inside surface can be anodized, otherwise the heatsinking of the outer grooves will lower a lot. Also also, lol, I got into a rabbit hole one day of essentially casting ( slip- casting ) a thin line of fire brick mix into the inside of the nozzle. Wish you all the success with your rockets !

[@AeroPropulsions]

@@rafaelguida2317 I'll need to see if the machine shop I order from can anodize only the inside surfaces! If they can, I definitely will give it a try! Appreciate the good wishes, best of luck with your experiments too!

[@rafaelguida2317]

@AeroPropulsions Thanks! If they can't do it only on the inside, I think it would still be worth a try, mainly to evaluate the protection from the coating. Just remember it needs to preferably be " hardcoat anodizing" AKA " type III anodizing " since normal anodizing creates a much thinner layer. I know JLCPCB can do it, and maybe xometry. Also, picking natural over black colour could help

[@pigalex]

@@AeroPropulsions if not, you could maybe have the whole part anodized, but you'd have to make the outer diameters larger so you could machine off the top layer to expose the "raw" aluminum. cool project btw!

[@makex_se]

That was cool! Exited to see more

[@AeroPropulsions]

Thank you!

[@daviddrift7663]

Subscribed and liked. A really interesting video. I will be watching!

[@AeroPropulsions]

Thank you so much!

[@Nabilphysics]

Thank you very much for sharing the details.

[@derekstarkjr5128]

Instead of a rubber O ring why not find a piston thats close 2 the same size and use its piston ring. File 2 fit.

[@Julian-wp8sc]

it may be possible that your ignition probe isn’t long enough to be starting the burn from the far end opposite of the nozzle. If your flame propagation is only slightly faster than the transversal speed of the flame in the core, this could lead to a slower pressure/heat buildup for the fuel to be simultaneously ignited. i suggest a finely ground KNO3 mixed into nitrocellulose (you can buy it as “liquid stich” at your local walgreens/CVS) lacquer to line the inside cavity of your fuel chamber. this mixture should also have the benefit of being decently resistant to moisture for startups in these winter months. hopefully this mixture (or something similar) can help get the core burning uniformly. i’m subscribing to see what happens next, good luck!

[@AeroPropulsions]

Thank you! Will be implementing this for the next static fire.

[@deucedeuce1572]

Would a thin insulator work to help protect the o-ring? There are some very thin, but amazingly effective heat insulators. I can't say I know them all, but I've definitely seen a couple over the years. Might be cheaper to just buy higher temp o-rings though. I just always try to do the research to think about all the options.

[@AeroPropulsions]

I am using o-rings that are rated for 400 F right now. Looking for some that are slightly higher and made from silicone!

[@lawrenceweaver1906]

Great work. I love this kind of content. A little tip for reducing the likelihood of o-ring failure at the nozzle is to cast the grain with a recess to the propellant that's at least equivalent to the liner thickness. On the nozzle there should be a shoulder on the converging end that fits snuggly inside the liner up to the recessed propellant. Upon assembly, load the motor from the nozzle end wnd use high temp(copper color) rtv silicone on the nozzle shoulder before inserting it into the motor. This setup gives you a free redundant nozzle end seal with the added benefit of weight reduction due to physically less material in the nozzle itself.

[@AeroPropulsions]

Thank you for your input! I’ll definitely take it into consideration. My concern is that using RTV could make it difficult to remove from the motor and disassemble later on. One of the main goals for these motors is to ensure they are easily reusable!

[@lawrenceweaver1906]

As long as you're careful with it, it's not that big of an issue. Put it on the lip of the liner so that any extra will squeeze inward. It will easily burn out during the firing. A trick I picked up from Richard nakka to get good ignition on hard starting knsb formulas is to paint any surfaces of the grain that are exposed to the flame front with finely powdered black powder that is suspended in acetone. After it dries store it as you would a normal propellant grain. Works wonders for keeping the startup pressure up for slightly longer as well as igniting the entire grain surface simultaneously.

[@tankkiller3386]

this is interesting stuff, keep making videos!

[@AeroPropulsions]

Thank you!

[@DidierGellert]

Bonjour, je regarde votre vidéo à l'instant, je fabrique des fusées depuis un moment, j'aime ça ! Je me limite à des buses en résines, j'ai des BEM en 316 mais j'ai envie de changer, j'adore votre vidéo et m'abonne dorénavant. Bon travail, je vous souhaite de très bonnes fêtes en cette fin d'année.

[@AeroPropulsions]

Thank you so much! Glad you enjoyed the video and subscribed. Best of luck with your rockets, and happy holidays!

[@HoangNguen-o2j]

Wow, your nozzle design looks alot like mine, for divergent half angle, have you ever consider using a lower angle like 2 degree, since for conical nozzle, that low angle is the most optimum for convert momentum into thrust.

[@AeroPropulsions]

I have not considered that but will be moving forward. Thank you for in input!

[@Kargoneth]

Fwoosh! Nice

[@Adrian-s6u2f]

🔥

[@Mrshotshell]

Instead of an oring graphite packing rope like is used in steam engines might be worth considering. Mcmaster has "High-Flexibility Steam-Resistant Packing Seals" rated to 1200F and 2500psi for a reasonable price

[@AeroPropulsions]

I’ll check that out. Thank you!

[@deucedeuce1572]

Would that slow start cause a failed launch?

[@AeroPropulsions]

Yes, at the beginning it was not producing around a half of pound of thrust. The rocket would eventually lift off at the end of the burn but wouldn’t reach the targeted altitude!

[@Brainstormer_Industires]

Seems like the burn through would be solved simply by making sure rocket isn't on fire for like 20 seconds before it actually starts burning for real. Getting all the propellant to burn properly will reduce the heat exposure time to what, 5 or 6 seconds total? Vs this test, which was like 25 with that pre-burn phase that wasn't generating any pressure.

[@AeroPropulsions]

@@Brainstormer_Industires Yup that’s exactly what we are doing! Next test there will be some modifications to the propellant to hopefully solve that issue.

[@RCreview-USA]

How much does this motor cost you, just the metal part?

[@AeroPropulsions]

@@RCreview-USA Casing: $25 Nozzle: $119 Bulkhead: $56. This doesn’t include shipping. Shipping can get expensive because it’s coming from China.

[@RCreview-USA]

@@AeroPropulsions Thank you. Would you be able to give me a link to a nozzle that you used?

[@AeroPropulsions]

@@RCreview-USA The nozzle is designed by me! If you would like I can email you the STEP file!

[@RCreview-USA]

@@AeroPropulsions Yes I would appreciate it.

[@AeroPropulsions]

@ Shoot me an email at [e-mail]

[@papakrakazyabrika]

👍👍👍

[@RogerSpace-sf5gj]

Thought this was a Uber fancy rocket stove haha woops

[@Jaystarzgaming]

Let the space shuttle screw ups be the reminder same O Ring problems.

[@meanman6992]

Use copper O-rings? Yes this means you would need to machine the nozzle differently and take a small weight penalty but since they basically work by brunch crushed between the two machined mating surfaces, I highly doubt they would fail.

[@AeroPropulsions]

Thanks, will look into it!

[@ImPrather]

any rubber will be destroyed after reaching those temps. id recommend using a carbon based seal like graphite gland packing

[@1992jamo]

Could you use multiple piston rings instead of o rings?

[@AeroPropulsions]

Thanks, will look into it!

[@hytralium]

Please make a discord, I would love to chat with you there

[@AeroPropulsions]

@@hytralium My username is anthonyfratello

[@ProlificInvention]

You sound like Christian from *JR Garage* on KZbin (his brother) Anyway, excellent video, I like what you're doing.

[@AeroPropulsions]

Thank you so much!

[@TomcatUncia]

any throat erosion with that heat and gunge (very technical) coming out the flamey end and sticking to the nozzle? any increase in diameter after this fire? maybe after a few fires? figure if its sugar mix prop there wont be any aluminium oxide coming out to erode as it passes, the small amount of iron oxide stabiliser and unburnt carbon particles may do some erosion after enough burns though.

[@AeroPropulsions]

No throat diameter changes were observed during this test. SN2 had a stainless steel diverging angle and throat insert, which successfully endured all four static fires without erosion.

[@tegensmith4769]

impressive! what igniters are you using?

[@AeroPropulsions]

@@tegensmith4769 I am using my custom made igniters. I have a video on how I make them! kzbin.info/www/bejne/gKCah2N7hcZsg7csi=riK6tWj_XcrdoC4i

[@railgap]

Give us the measurements. You are using a very safe, but not particularly high performance fuel. I am not recommending you attempt higher energy fuels however.

[@AeroPropulsions]

@@railgap I am using 22.75% milled KNO3, 42.25% granular KNO3, and 35% Sorbitol. I also add around 1-3% red iron oxide. Higher performance propellants in the future!

[@richardzeitz54]

Interesting! I'm curious as to why you'd use potassium nitrate rather than ammonium perchlorate or ammonium nitrate. I'll check your earlier videos. Is the iron oxide to catch infrared light from shining through the propellant, so it burns faster? That's my guess. You probably say in an earlier video. Cool reusable nozzle, btw!

[@en2oh]

Problem with the audio?

[@AeroPropulsions]

No problems on my end!

[@microbeMan]

Wouldn’t graphite be a reliable and useful rocket engine throat due to its very, very high melting point?(3600°C on google) and to compensate for its low tensile strength you can put a small, thin layer of aluminium or steel around it? Correct me if I’m wrong.

[@AeroPropulsions]

You're absolutely right! Most people use graphite nozzles, but I can’t go that route because I don’t have a lathe to machine the parts myself, and most machine shops won’t work with graphite. Luckily, sugar rocket propellant doesn’t burn as hot as something like APCP, so stainless steel works just fine for my needs!

[@eduardojud56]

no one polymeric ring will survive to this conditions... consider a metallic ring or maybe a graphite gasket

[@Testbug-dy6tj]

Fiberglass o ring.

[@78Lokal]

Pretty low thrust... Seems like fuel issue

[@viyye]

why do you call it nAzzle, it nOzzle

[@AeroPropulsions]

I don’t.

[@viyye]

@AeroPropulsions mate, the whole video is littered with it

[@AeroPropulsions]

@ Thank you for the feedback. I’m curious about your accent and where you are from!

[@viyye]

@@AeroPropulsions London

[@viyye]

@@AeroPropulsions watch your video, do you not notice it, i would find it amazing if you didn't pick it up, let me know if you do notice it upon a rematch

[@samw2768]

So what are you doing that a million others havent done? Anything new? Nope same ole bs done by a child that thinks theyre doing something new

[@AeroPropulsions]

@@samw2768 Thank you for the view and support!