Creating a Pressure-Fed Liquid Fueled Sounding Rocket

TopRamen said:

I think Ideas about this sort of thing are what the Research Section is for, or the "Personal Message"(PM for short), feature.

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Unfortunately i can't acces the research section.

LukaPeradze1 said:

Unfortunately i can't acces the research section.

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That's a bummer. I'm not even L1 in anything.
I just don't want to see you get banned or anything like that for a violation of some rule or something. Kinda' like how your not even supposed to post specific formulas about Pyrogens in the "Propulsion Section" but it's ok to talk about constructing your own Igniters in general.

LukaPeradze1 said:

Alright guys just a quick update i have attached a preliminary design of my feed system. Let me know what you think, and wether or not it is viable.


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I'm sure 99% of any 6th grader or older would come up with a drawing identical to yours if asked how to do the same thing, pretty basic. Drawing it up is the easy part, getting it to work is a different story. I would go with 2 separate compressed gas tanks totally isolating the fuel from the oxidizer tanks. The connection between the 2 worries me. That is just my first impression.

LukaPeradze1 said:

I think i havent stated my intention well. Im not going to be fabricating this myself, that would be as you said very time consuming/diffuclt/dangerous. I am designing the engine and the feed system in a CAD environment and then Sending it off the get CNC'd , i got a $200 quote for the engine i have attached below. Its a design i have been working on for a while. I thought id contact you guys as you have a lot of experience in the field, and i need help designing the pressure feed system which i have a general outline for. Thank you very much for your input


Sincerely,


Luka

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If it only cost $200 to make a liquid engine, you'd see a whole lot more people doing it. For reference, I am working on a similar project and can guarantee you it is quite a bit more involved (both technically and financially) than I think you're cutting it out to be. There's a bunch of things that seem to be left out, including valves, control/valve timing, thermal support, pressure support, an more.

rcktnut said:

I'm sure 99% of any 6th grader or older would come up with a drawing identical to yours if asked how to do the same thing, pretty basic. Drawing it up is the easy part, getting it to work is a different story. I would go with 2 separate compressed gas tanks totally isolating the fuel from the oxidizer tanks. The connection between the 2 worries me. That is just my first impression.

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I'd say that drawing has about <5% of the detail it needs, feeding both systems from one tank isn't much of a problem. That's not really what I would ask questions about first. My first questions would be along the lines of, where are your valves, and its oxidizer. Also paint might not be the best program to map out a propellant feed system in.

Luka, if you cant get access to the research section I won't be able to help you. If it is because you don't have a L1 cert, getting a L1 cert isn't that big of deal compared to what you are wanting to make and would be worthwhile to do. If it is because you aren't a US citizen I definitely cant help since I think propellent feed systems is actually one of the line items on the ITAR restricted list, and I am not a fan of million dollar fines.

I make it my policy to give the benefit of the doubt where-ever possible, since I remember what it is like to be on the other side of the table. I'm not sure you are at a point where I'd recommend pursuing a project like this. I'd really recommend spending some time researching the basics of what is going on before you want to move to making anything since you would only waste a lot of time and money not having the basics covered. There are some fantastic books on liquid engine design that you can get from amazon. I'd get one of those and work through some of the calculations to make an engine. $200 seems unreasonably cheap for CNC time. That would be about an hour and 15 minutes at the rates most shops charge, that wouldn't really get anything made other than the most simple shapes. As I said before the propellant feed system isn't really that complicated of a system for pressure fed rockets, if the overall concepts are giving you trouble you really should do more research. If it was a very specific question about one aspect of the feed system that would be an indication that you are more ready for a project like this.

Is anyone on here good with CAD that could make a 3d solid from my 2d drawings?

I agree with you thats its VERY basic, its just an outline of how i plan to do things. Currently im working on designing the injector and igniter for engine.

Im not really having much trouble, i just wanted to confirm my basic design before i begin. That drawing is just a basic sketch of what i thought of doing. obviously i have to add valves to control the flow rate and achieve a number i want. I do currently live in the US but this is my first time hearing about an L1 certification. If you cannot help my on the public forum you could email me as well. My primary question was on how to implement valves in order to achieve the optimal flow rate, and how i could remotely control them ( it though of maybe using an Arduino to control solenoid valves to control fuel/oxidizer flow.)

On Youtube they are a 13-15 years old Luka Peradze asking about sugar motors is that you ? .....

Probably not

Note that ITAR restrictions still enter into effect for transfer of info to a non-US citizen even if the location is in the US.

If you are really serious about this project, my suspicion is you are not yet at the point where you have an idea how much you don't know. I recommend two books:

Sutton - Rocket Propulsion Elements
Huzel and Huang - Modern Engineering for Design of Liquid-Propellant Rocket Engines

If you get interested in some historical cherry picked stuff, Sutton - History of Liquid Propellant Rocket Engines

Right now I know of four ways off the top of my head that liquid propulsion might be made to work simply and cheaply. At least two have been done before. To get any of them to work, would require lots of designing and lots of testing. Therefore no longer cheap...

If you can make it through the first two books and comprehend the contents, even do some of the math, then you should have an idea of how much you don't know. That's when you could, if you still choose, really start thinking about such a project. IMHO of course. Before that, it is just wishful thinking. This type of work is HARD and UNFORGIVING OF ERRORS. Just in case that point hasn't been emphasized enough!

Find a copy of the books and do some reading. That's my advice. You want to be reading the engineering texts, not the popularized stuff.

Gerald

PS - For background, I do research solids. I am working on my first research hybrid. Hybrid is much more complex as it throws liquids handling into the mix. It is a logical second step towards liquids.

(1) Learn about rocket propulsion in general
(2) Learn how to handle solids, and get experience
(3) Learn how to handle larger solids, and get experience
(4) Learn how to handle hybrids, and get experience
(5) Learn how to handle larger hybrids, and get experience
(6) Learn how to handle cryo and high pressure reactive liquids and gasses
(7) THEN think about doing a conventional liquid propellant engine!

Alternatively, get an aerospace degree and hire on with an organization doing the sort of work you want to do.

Alright guys what do you think of this design, its designed with regenerative cooling in mind, this is the engine i have been referring to which cost $200 to get CNC'd

I wouldn't trust a cnc shop that thinks that can be made for $200.

Ravenex said:

I wouldn't trust a cnc shop that thinks that can be made for $200.

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No kidding, that's some serious machining.

What kind of material are you planning to use to make that?

It's a very old basic design and if done right, it is probably fine. The devil is in the details though. What stainless or other metal were you going to have it machined from? Is there an adequate distribution of cooling channels to prevent severe thermal stress, and if not, can the material handle the stress plus working pressure? What are the properties of the materials involved over the range of working temperatures expected? Do you plan to have it survive startup sequence and a couple seconds of burn (an ablative liner might suffice), or do you plan to have it deal with continuous burn (the reason for regenerative cooling)? Do you plan for it to survive one usage, or to be reusable?

By the way, for pressure fed systems, there can be increased issues with feedback. If the chamber pressure goes up, there is reduced pressure drop across the injectors therefore flow goes down. Since flow has gone down, there is less reactive material in the combustion chamber so pressure drops. Since pressure dropped, there is a greater pressure drop across the injectors so flow goes up. Etc. Shake and bake. Very high quantities of accoustic energy and vibration.

For a project of any complexity, the place to start is being clear on your requirements. What are your requirements?

Gerald

LukaPeradze1 said:

Alright guys what do you think of this design, its designed with regenerative cooling in mind, this is the engine i have been referring to which cost $200 to get CNC'd

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You know, the "design" you've posted was not designed for CNC, rather 3D printing. There are plenty of sufficiently complicated features in the design that CNC just wouldn't get, especially not for $200. On top of that, it isn't going to produce enough thrust to lift too many sounding rockets, much less itself.

https://wiki.fubarlabs.org/FubarWiki/3D-Printed-Engine.ashx

This is not my design, it is a design i want to work off as the man who made it has had it 3d printed and worked. I just wanted some input on weather or not it would be viable. I think his meagre 50 newtons were cause by his different propellant choices, i intend to use LOX and Kerosene, and i though the regenerative cooling would ease my task a bit. im not claiming any credit for that design.

I do not know the propellant choices for the 3d printed version. But low thrust implies to me lower chamber temperature and pressure, therefore much lower heat transfer. I think you have a problem.

Gerald

And what exactly are you going to do with this engine? What is the purpose of the rocket? What is your budget? Where are you getting the materials? What are the materials?

I've noticed you never really answer the technical questions and often give vague answers to the questions you do answer. We've had other people come here and post similar questions and they are always evasive with their answers. Not a good sign in my opinion.

I apologize if i have been vague in my answers, i wanted specific responses to some of my questions. i should have state my intentions from the beginning. My goal right now is to create a rocket capable of reaching 5000 meters. In order to do this is am designing a liquid pressure-fed engine. For the actual creating of the parts/rocket, i am using the next line CNC service which is able to cnc with heat rolled steel, which i have chosen as it is cost effective and can withstand temperatures up to 1500 degrees celsius. As it is my first time constructing a liquid rocket i want some assistance with the pressure fed system. Now i have preatty much narrowed down the design, in terms of what i am going to use for valves,igniters,injectors....etc. I have seen some of the previous posts on this forum, where people were completely unaware of what they were doing, and of the complexity of liquid fueled rockets. When i started to post i wanted to make sure that i did not come across as one of these people, as that is not who i am. I apologize if my answers have been vague and amateurish, i hope i have stated my intentions well enough.

a 54mm L motor will take a 10lb rocket to more than 5000 ft (probably more).

You don't need a liquid fueled engine for that.

These are the guys you want to get in touch with, they have the design down pat. Exactly the type of engine you are thinking of. Just make up a smaller version of it. I seen it at the EAA, pretty impressive and would imagine pretty expensive. Also: https://www.xcor.com/products/vehicles/ez-rocket_faq.html


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taiwanluthiers said:

a 54mm L motor will take a 10lb rocket to more than 5000 ft (probably more).

You don't need a liquid fueled engine for that.

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Sorry i meant meters not feet.

This is a plane with a rocket engine....

taiwanluthiers said:

a 54mm L motor will take a 10lb rocket to more than 5000 ft (probably more).

You don't need a liquid fueled engine for that.

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Agreed. My highest has been 3,400 feet on a 4 grain 38mm I motor. 5,000 feet would be easy to do on a 6 grain 38mm I motor. You could go well over 5,000 feet on a skinny 38mm rocket.

5000 meters is about 15,000 feet. Any L2 motor will be able to take a fairly heavy rocket to that altitude. A L3 rocket will be able to take a very heavy rocket to that altitude, or way past that if it's a light rocket.

Getting a L2 or L3 certification is significantly cheaper than messing around with liquid fueled engines. A lot of people don't bother with hybrids because it's so much hassle. Multiply that by 10 for liquid fuels.

In fact most sounding rocket uses solid propellant unless they need to attain orbit (which by definition isn't sounding rockets anymore).

5,000 meters is a lot more than 5,000 feet; I read it wrong. You should have no problem hitting 16,400 feet (5,000 meters) with the right level 3 rocket and a commercial solid motor. Orders of magnitude cheaper than liquid fuels; plus a lot easier to launch. I've seen several rockets go near or over 15,000 feet from my club's field right here in Ohio. All they have to do is call in the waiver and light it. I have to believe that trying to get approval to launch a liquid fuel rocket would be a freaking nightmare.

a 3" Fiberglass rocket with a 54mm motor, using a L should be able to hit close to that altitude... a minimum diameter L should have an easier time.

54mm minimum diameter K350 from Loki can easily surpass 20,000'. Much cheaper as well.

Edward

You can also use a balloon if you want to keep it up there longer... much safer than rocket.