ap0r

KSP inspired me to design a liquid-fueled rocket engine

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22 minutes ago, Matuchkin said:

A thin layer of nickel-iron should do then, just lining the nozzle and combustion chamber

That's not easy at all, you know? Not everything can be used for lining. The active cooling part is correct.

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4 hours ago, kunok said:

That's not easy at all, you know? Not everything can be used for lining.

I know. I'm thinking of using titanium. Probably the easiest thing I know I can get. Easier than any other metal or metal alloy we mentioned.

What if the nozzle and combustion chamber are also lined with something that can melt easily, like plain old aluminum, on top of the titanium? What would happen? I'm thinking we can layer a small amount of something like titanium with an easily accessible metal- perhaps that will reduce strain on the titanium, or act like sweat and remove heat as it melts and falls off. At the same time, the active cooling system will also help, behind the titanium rear-layer.

I'm not an expert, and have never thought of an idea like this before. Just asking this question out of interest.

Edited by Matuchkin

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17 hours ago, Matuchkin said:

I know. I'm thinking of using titanium. Probably the easiest thing I know I can get. Easier than any other metal or metal alloy we mentioned.

What if the nozzle and combustion chamber are also lined with something that can melt easily, like plain old aluminum, on top of the titanium? What would happen? I'm thinking we can layer a small amount of something like titanium with an easily accessible metal- perhaps that will reduce strain on the titanium, or act like sweat and remove heat as it melts and falls off. At the same time, the active cooling system will also help, behind the titanium rear-layer.

I'm not an expert, and have never thought of an idea like this before. Just asking this question out of interest.

You are looking for an ablative material, aluminium isn't a good option as far I know. I don't know much about ablative materials sorry.

For cheap high temperature materials look for ceramics, I even have seen a project that made the worst part of the engine (it was a static one too) in concrete, but i don't remember where i seen that. The problem is that they are a lot more fragile. If you are able to get it, graphite is a good option too.

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Once you have the test stand working, you should weigh the tanks full and empty and add the engine/plumbing weight to the tanks dry weight.

I wanna know how much delta V it has :D

What about TWR? 

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3 hours ago, KerbonautInTraining said:

Once you have the test stand working, you should weigh the tanks full and empty and add the engine/plumbing weight to the tanks dry weight.

I wanna know how much delta V it has :D

What about TWR? 

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

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Hello! I have another update! The cooling design is almost complete :D
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?

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Well I want to see the cad of the cooling jacket, maybe you can make the jacket with a standard pipe of 50mm, so you only need to machine the start and the end of the jacket.

On 17/5/2016 at 2:10 AM, ap0r said:

Also, would you rather have smaller updates more often, or larger updates with more time in between?

I like both ways, but maybe put each day in a different spoiler tag?

Like:

May 16th

Spoiler

example

May 18th

Spoiler

example

 

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Hey @ap0r what does your injector geometry look like also just using water as coolant and then dumping it?

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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.

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about cooling:
is it possible to cool the engine ablativ? ->
lingter engine, but waste after use....

there are som firms that can create something from a graphit block ...

Edited by Sereneti

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4 hours ago, Sereneti said:

about cooling:
is it possible to cool the engine ablativ? ->
lingter engine, but waste after use....

there are som firms that can create something from a graphit block ...

It's going on a test stand, so weight doesn't matter.

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On the side of things that might go boom, have you considered ballistic curtains?

As far as ignition goes, considering the design of your nozzle is specificaly arranged so as to not allow exhaust gasses to pass back into the commbustion chamber, maybe an ignition source at the exhaust wont work so well? Ive seen videos of pulse jets being lit with a bit of burning tissue paper (low residue) placed in the combustion chamber before fuel is added. You might need to trickle in a little oxygen so it doesnt smother too fast, but the flow rates of reactants you have worked out should be more than enough to eject it. Safer than lighting it by hand...

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5 hours ago, Sereneti said:

about cooling:
is it possible to cool the engine ablativ? ->
lingter engine, but waste after use....

there are som firms that can create something from a graphit block ...

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.

1 hour ago, KerbonautInTraining said:

It's going on a test stand, so weight doesn't matter.

Exactly.

30 minutes ago, SinBad said:

On the side of things that might go boom, have you considered ballistic curtains?

As far as ignition goes, considering the design of your nozzle is specificaly arranged so as to not allow exhaust gasses to pass back into the commbustion chamber, maybe an ignition source at the exhaust wont work so well? Ive seen videos of pulse jets being lit with a bit of burning tissue paper (low residue) placed in the combustion chamber before fuel is added. You might need to trickle in a little oxygen so it doesnt smother too fast, but the flow rates of reactants you have worked out should be more than enough to eject it. Safer than lighting it by hand...

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 :)

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1 hour ago, ap0r said:

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 :)

Can you make a video? :)
 

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

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I posted this on the wrong thread previously, so don't be confused if you see this there.

I have two important questions to ask:

1. What will it be like to use H2O2+_____ as a bipropellant mixture in this scenario? I'm thinking of H2Oand kerosene as a mixture- seems easy to get.

2. Where can one get potassium permanganate?

Edited by Matuchkin

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Hello. The engine is designed for methanol-gox. Other propellants will result in different pressure, temperature, mass flow ratio, mix ratio, a different gamma value, and so on. Without making calculations I can't tell for sure.

You can get potassium permanganate at any drugsture, it comes as purple pills that you dissolve in water to treat feet fungi. But then again, if you're using potassium permanganate as a catalyst to decompose the peroxide you're probably thinking of a monopropellant engine?

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Hello all... Not a real update today. I don't have time. But I-ve reviewed everything, fixed typos, added more data, a video on expansion, and a list of my reference material if any of you wants to do a similar project :)

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Hello again I have a couple questions that I was hoping you could help me with. I was wondering if you could tell me where you found the fact that in small hobby rockets that the average heat transfer from the hot gasses to the chamber walls is about 0.5 Kw/cm2/sec. Also, how do these units work out because doesn't average heat transferred have units of W/m^2 not W/m^2/sec. Next, could you expand on what you mean by using two reservoirs to bring the water leading to the cooling jacket up to 10 m/s. Thank you for everything.Your updates have been very helpful.

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18 hours ago, views1995 said:

Hello again I have a couple questions that I was hoping you could help me with. I was wondering if you could tell me where you found the fact that in small hobby rockets that the average heat transfer from the hot gasses to the chamber walls is about 0.5 Kw/cm2/sec. Also, how do these units work out because doesn't average heat transferred have units of W/m^2 not W/m^2/sec. Next, could you expand on what you mean by using two reservoirs to bring the water leading to the cooling jacket up to 10 m/s. Thank you for everything.Your updates have been very helpful.

Yes, sorry. The original data was expressed in BTU's, that's the origin of the confussion. Should have used Joules :D and I got it from "Designing, Building and Testing Small Liquid fuel rocket engines"

By using two reservoirs I mean the water pressure and flow rate straight from the tap or the tank where I live are not high enough to cover this, and thus I will need a reservoir and pump to provide the desired flow rate.

Another update is coming as soon as I can find the time. Between work, flying, and studying I'm usually too knackered to do anything other than crawl into bed every night

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Finally found a bit of time for a small update! The cooling system is finished, next up, injectors!

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On ‎01‎/‎06‎/‎2016 at 4:34 PM, ap0r said:

Hello. The engine is designed for methanol-gox. Other propellants will result in different pressure, temperature, mass flow ratio, mix ratio, a different gamma value, and so on. Without making calculations I can't tell for sure.

You can get potassium permanganate at any drugsture, it comes as purple pills that you dissolve in water to treat feet fungi. But then again, if you're using potassium permanganate as a catalyst to decompose the peroxide you're probably thinking of a monopropellant engine?

No, this is important. I'm thinking of a simple gas-generator, to power your fuel pump. It's not as complex as you think. All that you have to do is:

- Dump those aforementioned KMnO4 (potassium permanganate) pills into a can.

- Pipe pressurized H2O2 into it. The reaction will create hot, pressurized steam.

- Steam automatically goes out the other end of the KMnO4 can and can spin a turbine.

Edited by Matuchkin

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