Hybrid engine questions?

Discussions of motors from single-use and RMS solid propellants to hybrid propellants

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J.gray
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Hybrid engine questions?

Postby J.gray » Tue Mar 23, 2021 8:24 pm

Hi everyone,

First post on here so don't bite my head off if I say something completely stupid. The background to this thread is that I need some help with designing the oxidiser system in a hybrid rocket that myself and some other student friends of mine are making. I have dabbled in solid motors before so I think I have a few core concepts down. Obviously this is the first time myself and my friends have tried to branch out into hybrids so we are seeking some help. We have also enlisted the help of a few aerospace engineering students at Imperial University in London, however they don't have much if any experience in hybrids so they are just helping with nozzle and aerodynamic equations right now. Sorry for that very long winded explanation however I believe full transparency is best. Hopefully some of you guys can help us out with all your knowledge!

1. How does one turn gaseous nitrous oxide into liquid nitrous? Is it just down to pressurising the gas to a certain point (critical pressure + temp)?
2. Is mixing glue sticks into a paraffin fuel grain a viable option to stop the wax from melting so easily and expelling un-combusted droplets out of the engine?
3. Has anyone got any experience using aluminium powder in order to increase the regression rates in paraffin fuel grains, and if so is around an 8% aluminium powder 92% paraffin mix to low or high?
4.Could somebody possibly explain to me there own GSE if they have any experience with an N2O system whilst flying hybrids (pictures would also be doubly helpful but don't sweat it).

I really would appreciate any answers/criticisms to any of the above questions and I'm sorry if I sound a bit stupid but we all have to start somewhere.

Many thanks.

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kopius
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Re: Hybrid engine questions?

Postby kopius » Wed Mar 24, 2021 6:35 am

Hi J.Gray, welcome to the forum. There are a number of people on here who have solid knowledge of hybrids.

Before anyone jumps to far in the weeds though, would you mind doing a post to give some background on yourself and the project? Would appear you are a university group, which uni? Are you in Australia? What is the end goal for you and the team?

Looking forward to some more context to ensure the right info is put forward.

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J.gray
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Re: Hybrid engine questions?

Postby J.gray » Wed Mar 24, 2021 10:04 am

Hi,

Sure thing. Myself and the team (2 other guys) are all 17 years old in year 12/Lower 6th of secondary school in the UK (sorry I don't know the equivalent in the Australian education system). Whilst we are not at university yet we have contracted the help of a few aerospace engineering students to help us when the equations get a bit out of our depth. We are designing and building the hubris engine, and eventually an airframe for it to fly in, for a few reasons. One member of the group is writing a dissertation on hybrid rocket engines and needs to include a practical element and the other two, myself included, are mega space nerds. We have all dabbled in solid rocket engines and done launches however we all wanted to challenge ourselves with a hybrid engine. We have currently done 2 static fires of the engine and it works. We are using GOX and paraffin currently however after we have developed the engine further we are planning to fly on N20 and paraffin for oxidiser density (therefore weight) reasons. Just to clarify we are not going to fly not the same engine with both GOX and N2O however we are using the GOX/paraffin engine to work out design flaws and get experience in designing nozzles and doing nozzle equations as well as just basic engine building and design. We have received support from our school's physics department, however their knowledge on such questions as posed before are limited.

Sorry if I rambled a bit just wanted to give you as much information as possible.

Jack

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Re: Hybrid engine questions?

Postby Voyager » Thu Mar 25, 2021 9:17 pm

I don’t know whether you noticed, but there is a sub forum on hybrids here: https://forum.ausrocketry.com/viewforum.php?f=7u
Some of your questions might be answered here.
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