ap0r

Of course you can make hydrazine more easily. That is not the point, wich sadly, you seem to be missing entirely. If you want to proceed with this dangerous chemical against all advice, on your head be it.

Hello @KSPNewbie and thanks for the mention @KSK Now for your plan. Believe me when I say I'm not a person prone to theatrics or exxageration, but I simply cannot find words strong enough to stress how big of a bad idea using hypergolics is. Really, I'll use caps and a big font to get the point across. This stuff is R E A L L Y , R E A L L Y N A S T Y Yes, as mentioned I'm designing a liquid-fueled rocket engine. One of the first choices was propellant, and in fact I did consider hypergolics, just like you. While I did not post the pros and cons of each fuel combination, I have it on hand. Let me paste here Hydrazine/NTO: Pros: Ignites on contact, reliable and simple ignition Storable for long periods of time Non-cryogenic Cons: Corrosive. (It eats through stuff) Toxic. Like, DEADLY toxic. Carcinogenic (It makes you get cancer) Ignites on contact (safety) Really hard to find (Really, I had to write to CONAE and they told me they imported it directly from the manufacturer) - this point may be moot outside of Argentina Can only be bought in bulk (this point valid only in Argentina, I think) Extremely expensive. This is just a supposition, after all I was unable to get a quote. Real life rocket scientist are trying to their best to find a replacement for it. That's how bad it is. This for Hydrazine: According to the U.S. Environmental Protection Agency: Symptoms of acute (short-term) exposure to high levels of hydrazine may include irritation of the eyes, nose, and throat, dizziness, headache, nausea, pulmonary edema, seizures, coma in humans. Acute exposure can also damage the liver, kidneys, and central nervous system. The liquid is corrosive and may produce dermatitis from skin contact in humans and animals. Effects to the lungs, liver, spleen, and thyroid have been reported in animals chronically exposed to hydrazine via inhalation. Increased incidences of lung, nasal cavity, and liver tumors have been observed in rodents exposed to hydrazine.[40] Limit tests for hydrazine in pharmaceuticals suggest that it should be in the low ppm range.[41] Hydrazine may also cause steatosis.[42] At least one human is known to have died after 6 months of sublethal exposure to hydrazine hydrate.[43] And this for NTO: EXPOSURE AVOID ALL CONTACT! IN ALL CASES CONSULT A DOCTOR! Inhalation Cough. Sore throat. Shortness of breath. Dizziness. Headache. Burning sensation. Laboured breathing. Nausea. Symptoms may be delayed. See Notes. Use breathing protection, closed system or ventilation. Fresh air, rest. Half-upright position. Administration of oxygen may be needed. Refer immediately for medical attention. Skin Redness. Burning sensation. Pain. Serious skin burns. Protective gloves. Protective clothing. First rinse with plenty of water for at least 15 minutes, then remove contaminated clothes and rinse again. Refer immediately for medical attention. Eyes Redness. Pain. Severe burns. Wear safety goggles or eye protection in combination with breathing protection. Rinse with plenty of water for several minutes (remove contact lenses if easily possible). Refer immediately for medical attention. Ingestion Burns in mouth and throat. Do not eat, drink, or smoke during work. Rinse mouth. Do NOT induce vomiting. Refer immediately for medical attention. Basically, and to reiterate, this is a bad idea from your personal safety and budget viewpoint. I strongly suggest considering alternate propellants. Your propellant choice should be tought out, and not be "something cool you heard about", but "something that does what you need it to do, in the most safe way possible, and with minimal expense" Sorry for the wall of text but this is paramount to your safety, and also if you're involved in an incident/accident the media will cast bad light on all hobby rocketeers indiscriminately as it has happened in the past. If you need any advice, feel free to write me. Mind, I'm not an expert by any means, but I have devoted some time to study these matters, and much time to thinking about it. PS: I reccomend you get these books: Design of Liquid Propellant Fuelled Engines Designing, Building and Testing Small Liquid fuel rocket engines Ignition A History of Rocket Propellants <- Especially this one, it'll really open your eyes about hypergolics. Sutton-Biblarz-Rocket_Propulsion_Elements Once again sorry for this lengthy post but I wanted to get the point across really clearly.

Yes, video will be part of the documentation after it is built.

Yes, this was talked already and ablation cooling is possible, but I choose simplicity and cheapness over mass. Also a graphite nozzle would be cool, but the price of a graphite nozzle in my country would be more expensive than 3 copper chamber + nozzle assemblies. Exactly. On the side of things that might go boom: A) The cooling jacket doubles as a shrapnel shield. B) Engine will be operated remotely from behind a wall, and looked at with mirrors. C) Since I don't care about mass, all pressurized parts are designed to very high safety margins. Thank you all for your feedback and time

Hello @B787_300, injector geometry consists of a commercial spray nozzle for fuel and impinging holes for oxidizer. The water will come from a reservoir, as there is no way i'm getting the required flow out of a house pipe, and head out to another reservoir to avoid waste.

Like this, @kunok

Hello! I have another update! The cooling design is almost complete As always, start on today's date in the first post of the thread, or, if you're new, start from the beginning of the first post of the thread. If you have any sort of suggestions, ideas, doubts, or even better, think you've found an error, please, do let me know! Thanks You guys rock. Also, would you rather have smaller updates more often, or larger updates with more time in between?

All of that and more will be measured once the engine is operational.

First of all sorry for the delay. Work has been hectic. Now, @Matuchkin your project seems to go way beyond my extremely low expertise at this moment. If there's anything I can help with, sure, do contact me, but you are planing on using a gas generator, a turbopump, a combined regenerative/ablative cooling system, all of wich I've deemed too complex/expensive to tackle right now... So I'm not realy sure how I could be of any help. And @kunok, you're spot on.

Are you actually building that or just thinking out loud? That'd be insanely cool! Also @views1995 if you don't mind waiting a bit, detailed design of the cooling system should come along soon, but this might be a good reference meanwhile.

Well first of all I'm no expert, I'm learning myself so take my advice with a lot of salt. That said, kerosene should give you higher pressures, wich are no problem with a thicker copper wall, and higher temps, wich might make cooling challenging. Titanium is usually not used in rocket chambers, Inconel is a more common material. So I'd definitely recommend you stick to copper for a hobby engine. You'll have to make thicker walls, of course, but titanium seems like it'd be much more expensive, harder to machine, and also cooling would be a more complicated.

Hello! I have a short update today, on cooling. As always, start on today's date in the first post of the thread, or, if you're new, start from the beginning of the first post of the thread. If you have any sort of suggestions, ideas, doubts, or even better, think you've found an error, please, do let me know! Thanks You guys rock. Also, would you rather have smaller updates more often, or larger updates with more time in between? @KerbonautInTraining Yes, I first tougth of that, but the radiant heat of the plume would probably be enough to destroy my plastic mini-torch lighter, that's why I've yet to come up with a decision on ignition method. Also, the main post got updated

Actually I had tought abouth both methods and I'm undecided between electric ignition, or just sticking one of those kid's fireworks that make lots of sparks up the nozzle. The firework should be much more effective than a piezo sparker, but it might also leave residues... not fun at all! I will have to make tests in order to determine wether the residue is something I can tolerate.

Thanks @FleshJeb. That must have been a cool experience, and you certainly have a valid concern. However, my primary reference material is specifically oriented towards the design of small engines. I of course cross check with other books, and yes, I have found a few differences attributable to scale issues. Thanks for your feedback, and if you think you have any ideas or even better, have found a mistake in my calculations, please, do let me know.

A commercial oil furnace spray nozzle for the fuel and two impinging holes for the oxidizer.

Yes, it's designed already. This was just a sketch to show the new geometry (hence the flat plate at the end). An update may take a few more days to come along because real life is kinda of in the way. But I wanted to show that because it looked way cooler than the original one. It's just that it takes a lot of time to convert from my design notes to something that flows along, includes explanations for stuff I barely understand myself and still makes sense somehow... Time wich I don't happen to have in spades right now.

New nozzle geometry looks much better @A Fuzzy Velociraptor... Thanks!

1) I tought about using compressed air, as oxidizer, but that is not fun imho. All the GOX fittings, pressure regulators, etc, only have to be bougth once, and are then installed in my "test stand" and can be utilized in future designs. 4) I will redesign the nozzle/chamber assembly. Same inner dimensions and wall thickness (pending cooling review), but with this simpler geometry. Thanks for your toughts and feedback, it really is appreciated.

Hey! Thanks for yout toughts, much appreciated! In response to your points, 1) Yes you can but the math is horrible. About o/f ratios, I mention that " There is an exception to that if running fuel-rich reduces the molecular weight of your exhaust, such as in hydrogen burning engines, but that is honestly beyond the scope of this discussion " so maybe you missed that part But really, I'm not aiming for max performance. I'm aiming for simplicity. 2) All relevant calculations are performed with EE units. I use metric in my head, so I usually convert back and forth, but yes, I have taken the empirical nature of the equations that you mention into account. 3) I'm designing for indefinite run time, with a cooling jacket, but will operate it in 5 second increments, up to a max of 30 seconds when I have done many many test firings. Surely that is overkill, but then again, i'm not aiming for a lightweight engine here. 4) It surely would be easier to design, but I worry about the angle on the throat, where the nozzle and inlet are joined... A sharp corner there seems like it would be counterproductive? This requires more tought. 5) That is already taken into account, I will use pressure regulators to get constant oxidizer and fuel pressures despite variations in tank supply pressure with expansion. Once again thanks for the feedback, it sure is appreciated! Thanks! AndThanks Basto to you too

You are absolutely right on that one. Tomorrow I calculate cooling, and depending on the results of that I might recalculate wall thickness. Thanks. So obvious... can't believe I would have missed it

Took me forever, sorry for the delay, but i've finally cmpleted the chamber and nozzle design. Coming up is cooling system design. As always, start on today's date in the first post of the thread, or, if you're new, start from the beginning of the first post of the thread. If you have any sort of suggestions, ideas, doubts, or even better, think you've found an error, please, do let me know! Thanks

Just googling Wageera Aerospace to see if I wasn't stepping on any real life company's toes nd found this thread. Thanks for the mention, and be assured there are other spacecraft and aircraft in the making.

Hey, finally found a bit of time to update the project. Sorry for the delay but Real Life has to come first. Otherwise i'd starve to death. As always, start on today's date in the first post of the thread, or, if you're new, start from the beginning of the first post of the thread. If you have any sort of suggestions, ideas, doubts, or even better, think you've found an error, please, do let me know! Thanks

Well if something goes wrong they can be pretty destructive, but it'd still be classified as an accident because the device was not meant from the get go to explode.

Hello! It took forever, but finally I got a breather from Real Life Stuff. As always, start on today's date in the first post of the thread, or, if you're new, start from the beginning of the first post of the thread. If you have any sort of suggestions, ideas, doubts, or even better, think you've found an error, please, do let me know! Thanks @K^2 i'd appreciate you checking things over. Your feedback has been real helpful.