Exactly. I feel like TH-cam is missing comprehensive video series on rocket engine design. Feel free to make longer in-depth videos. Can't wait for next one. Thx BPS!
This is fantastic, there is essentially no content online for hobby scale liquid rocket engines. I've always wanted to do this as a project. Thanks for great intro video, can't wait for the rest of the series 😁🚀
Man, you really got me going now. I didn't know how to even start doing the math, I've made the stoichiometric calculations to have a perfect fuel / oxidizer ratio but never figured out where to go then. This was a quick "tutorial" but really easy to understand for the average mind! Thank YOU!
Thank you for attempting this sort of challenge. I have been longing to see how I can produce one for use on high power rockets to send small payloads to high altitudes, not to mention my university has brought up the possibility of developing one from scratch. However, I do not quite know where to start other than reading and taking notes from "An Introduction to Rocket Science and Engineering" as well as reading "Ignition!" which, admittedly probably isn't enough for me to fully understand how they are constructed.
Hi, thank you SO MUCH for this. Learning so much here compared to what I learned in class. It was mostly theory, but all of this is practical. Just another reminder that you're a really big help. hope you're doing well.
Charlie what level are you? Those are some pretty beefy rockets in the background. I just got my L1 certification yesterday. You set off much of my interest in space at the Cosmosphere and it literally changed my life. Thanks for the great years, man!
Wow! That is amazing! Very interesting topic, liquid rocket engines seems like a very complex thing 🤔 Looking forward for next video! PS. Thanks Joe for bringing me here!
I’m 15 and making solid propellants for my rockets. Making a liquid fuelled engine is definitely my next project once I have a bit more experience with liquid propellants... a lot more experience 😄
This video made designing an engine incredibly simple! New subscriber :) I'm *attempting* to design a 3D printable rocket engine that won't melt. Easier said than Done!
If/when I get back to college, I want to eventually design and build a ~1kN MethaLOX engine, so if you don't mind I'm gonna be taking some serious notes, so if you want to go beyond the layman's explanations into truly nitty gritty masters details, please do cause I'm gonna need all the help that I can get to have a basic head start before I get back.
I don't talk about it here, but I did design work on a 2kN methalox engine. Machined a lot of test parts, but we had problems with supercritical methane injection, cooling, and generally inexperienced choices made early in the design. I'll throw deets in later videos.
If you're still interested, i've found using NASA's CEA ( cearun.grc.nasa.gov/ ) on the rocket mode will tell you almost anything you want so long as you spend a bit of time figuring it out.
@@robbiejames1540 Thanks for the link, I've bookmarked it! Unfortunately I'll be putting any return to classes plans on hold until the pandemic ends, but I've been gradually learning basic and above basic equations and concepts I previously hadn't learned yet. If I can learn some thermodynamics and become more acquainted with it as pertaining to the gas laws, I could potentially design a simplified rocket engine, or at least familiarize myself to the equations for one, before I make any real plans.
How do you purpose to deal with heating of the combustion chamber and the nozzle. Thanks if you have time do you have time to talk to a old guy about a few ideas
Hi Charlie. First of all, thank you for sharing your knowledge with us. It's really great to see other rocket engineers ideas. But I believe I have found some error in your calculation of enthalpy of formation. 2:01 From WIKI (en.wikipedia.org/wiki/Standard_enthalpy_of_formation ) enthalpy of formation for C2H5OH -277.0 kj/mol H2O -241.818 kj/mol CO2 -393.509 kj/mol. As far as I know, enthalpy of formation 3*(-241.818)+2*(-393.509)-(-277.0) = -1235.472 kj/mol. If I'm right, for 1mole of ethanol 1235 kj of energy is released. Feel free to correct me if I'm wrong. Again thank you for making this video. bye
Normally, you'd be right! However there's a phase change or two to remember, since we'll have liquid reactants and gaseous propellants. The other secret is that software does this now-a-days with much higher fidelity because it can consider reactions that don't run to completion, and disassociated products in the exhaust stream.
Nomenclature; correct me if I’m wrong, but c* is typically used for characteristic velocity, c is exhaust velocity, not the same quantities (c* isn’t even a real velocity)
2:44 does anybody know how he gets to 3030K here? I only get something around 7000K, and when I use high temperature values for cp, I get to slightly above 4000K. So I must be making a mistake somewhere
I'm so excited for more! Also promise me if you get it to work that you'll put a marshmallow coated in phenolic ablatives into the exhaust and attempt to roast it
Follow his lead and build a small one first, not like me who try'd to build a 5Kn engine right away. Short version I ended up putting the 5Kn on hold to build (and now done test firing) a smaller one first.
if anyone is still curious on how he got all these values on his calculations, learn to use CEA. trust me, there is a LOT of things going on behind the scenes adn unfortunantly he does not go into much detail at all on how to do this yourself. this is just a intro. read RPE and do a little CEA and you will be able to get similar numbers to what he got. best of luck
@@Outsoldier hello man, RPE stands for rocket propulsion elements, from Sutton. It has been a year since I started my rocketry project and I also recommend RPA which stands for rocket propulsion analysis. Super useful program. Currently writing a journal of how to make a rocket engine step by step, so if you are interested drop by my channel at some point for it. Unlike most videos on TH-cam I will publish my project to the public as a open source project so that anyone can replicate it and modify it. I also plan to make a discord server for people such as you and me to share their knowledge in a centralized place without the fear of being gatekeeped out of the hobby. Have a nice day.
Hi Charlie ! Thanks for your great explainations about Rocket engines But I've tried many times to calculate an adiabatic combustion temperature, and every time I get a crazy value like 5000K, and you got a decent value here, how did you do ??? What values should I take for DH, and the heat capacities ??
Any recommended books to learn about this kinda stuff? I'm in high school rn and I really want to learn! I don't care if they're technical or involve some math as long as I can mostly understand them :) 📖
Hello, im working on a 1.4kN liquid rocket engine for a high school project. My calculations somehow led to a very long combustion chamber. Could a longer combustion chamber lead to more instabilities or somehow endanger the engine itself. From what i know, it just loses its energy.
We'll talk about combustion chamber design in a few weeks, but especially for small engines, the chambers look disproportionately long in order to get good combustion efficiency.
Hey Charlie, at 1:59, when calculating heat released, 1145 kJ/mol is the enthalpy from the reaction, right? I saw from another site that the reaction of ethanol with LOX is 1368 kJ/mol instead. Is there a reason they're different? Am I looking at the wrong value on here - www.ausetute.com.au/heatcomb.html? Thanks! Awesome series!
how did you get Cp of co2 and h2o because from what i see it changes with temperature and you cant calculate it without so did you just use a prediction?
How did you get 32.25 megajoules/kg? If 1000 grams (1kg) of propellant were used(oxygen included), 32 percent by mass would have to be ethanol. In 320 grams of ethanol, there are about 7 mols ethanol. 7mol times 1145 kJ/mol is 8015 kj or 8 mj/kg propellant. Even if you burned 1000 grams ethanol in excess oxygen, it would only equate to about 24 megajoules. Maybe I’m missing something?
alright I want to make one but I want some books about it first so I can understand all the equations you used also where did you learn what you to make this engine if there are books can I get the names and links
I’m so glad I found your channel! I’m going into my sophomore year of college, and have a similar goal (rocket engine build) I want to reach by graduation. Based on your injector design, I’m guessing you already know about them, but I recommend checking out Copenhagen suborbitals. They walk through a bunch of cool stuff (not just the propulsion system, but....) and they really got me interested. Also, could I ask what books/videos you primarily used to get started? (Unless it’s all from class)Thanks a ton, and can’t wait to see more! Isaac Davanzati
Hi Isaac, I'm quite familiar with Copenhagen Suborbitals, I was quite inspired by them myself back in the late -oughts (jeez I feel old...) MIT's class notes are linked in the description. For texts, I used Huzel and Huang's excellent guide on small rocket design and Sutton's Rocket Propulsion Elements to start.
Ok I need a workshop, some materials, ethynol, LOX, and a test stand. I am actually curious tho, my friends and I are designing a rocket and I was wondering if I should use a hybrid or liquid fueled engine. I’m aware of the pros and cons of both, I just want a 2nd opinion.
For the equation C*^2/2 = CpTc, does this consider pressure increase from released gasses? Is pressure increase negligible or does it somehow get factored to the derivation of this expression, in due to using Cp instead of isobaric specific heat? Would it not be possible to use ke = mv^2/2 to estimate characteristic velocity, using entropy in addition to enthalpy, to get an estimate of best case conversion from chemical energy to exhaust velocity?
Great video, I'm excited to see the rest. I'm also working on building my first engine this summer. I've decided to code all the nessecary equations in Matlab so that I can optimize them faster and compare other design choices on the spot. Do you have any experience with Nitromethane? I've read about it being used as a monoprop and I'm interested in trying to use it with Nitrous Oxide although I'm prepared to switch to another hydrocarbon for my fuel if my calculations push me that way. Also hoping to use a pintle injector with face shut off. My goal is to iterate until I have built a fairly reliable engine that I can then use to test other ideas that I have.
I'm curious what you plan to optimize for. Especially for the first engine you build 'robustness' is usually the most valuable quantity, but there isn't an equation for that. I've heard of nitromethane being used as a monoprop in torpedos, but I'm not super excited to go and try it. In a biprop, there are cheaper, higher performance, easier to obtain, stabler fuels, and even some with all of that in one.
When solving for the temperature of combustion, how did you find delta h? I get finding specific heats and your initial temperature, but I can't figure out how you found your change in enthalpy?
Hi Charlie, thank you for your videos. Is your equation for exit velocity for choked flow only? Then I assume you wouldn't have a divergent nozzle? I ask because the equation NASA gives for exit velocity = Exit Mach * sqrt( Gamma * Gas Constant * TempExit ).
Can't wait to see more, great work, Charlie!
You should build him some SRBs
It will be great if you both collaborate and build a rocket ..
Vineeth BA oh. My. God. Yes. Joe could design the flight computer and gimble system while Charlie makes the engine
hey! you are here too!
BPS.space!!
I would love to see you develop and test this engine.. Together with BPs space this is getting interesting. :)
Here to see all the videos till the end result! Good explanation!
Looking forward to seeing this project advance. I really hope you take us along for the full ride.
Exactly. I feel like TH-cam is missing comprehensive video series on rocket engine design. Feel free to make longer in-depth videos. Can't wait for next one. Thx BPS!
This series sounds awesome! The more in-depth the better.
This is fantastic, there is essentially no content online for hobby scale liquid rocket engines. I've always wanted to do this as a project. Thanks for great intro video, can't wait for the rest of the series 😁🚀
Man, you really got me going now. I didn't know how to even start doing the math, I've made the stoichiometric calculations to have a perfect fuel / oxidizer ratio but never figured out where to go then. This was a quick "tutorial" but really easy to understand for the average mind! Thank YOU!
Even more excuses for me to build a propulsion test stand..
interesting first order explanation to get a feel of the scale of the numbers. thanks.
Most legendary Cosmosphere counselor of all time
Thank you for attempting this sort of challenge. I have been longing to see how I can produce one for use on high power rockets to send small payloads to high altitudes, not to mention my university has brought up the possibility of developing one from scratch. However, I do not quite know where to start other than reading and taking notes from "An Introduction to Rocket Science and Engineering" as well as reading "Ignition!" which, admittedly probably isn't enough for me to fully understand how they are constructed.
Count me in on this. The more depth you're willing to provided in your process, the better, imo :)
I ended up here because of BPS' recommendation in his community post
absolutely ecstatic that you finally posted this
Hi, thank you SO MUCH for this. Learning so much here compared to what I learned in class. It was mostly theory, but all of this is practical.
Just another reminder that you're a really big help. hope you're doing well.
Please please please do more videos about this topic. This is great!
This is awesome! I can't wait to see this work.
Charlie what level are you? Those are some pretty beefy rockets in the background. I just got my L1 certification yesterday. You set off much of my interest in space at the Cosmosphere and it literally changed my life. Thanks for the great years, man!
I'm so excited to hear that! I'm honored you remember me. I earned my L3 on an M1650 two years ago with the black and blue rocket in the left corner.
I am interested in seeing all those things that you just suggested. Awesome concept for a channel!
Subscribed and SUPER interested in all the nitty gritty details!
BPS sent me over, I’m super excited to see what you do since I’m going into my junior year studying these mechanics.
I'm very interested to see more of this project!
You got me interested! Looking forward to your next video.
I think the people watching these videos would appreciate as much detail as possible 😂
Sure enough
Please continue with the series even if you fail. Eagerly awaiting the next episode
4:16 @CharlieGarcia How may this process be done? is it just based of the price and how much fuel is used? just wanna make sure
I saw you on bps space. Would definitely be interested in all the nitty gritty details of the whole design process behind this
Very nice and interesting video, it could be nice to see more !!
Good luck Charlie. Very interesting.
Go deep man! It's really cool seeing the thermodynamics behind the engine.
great presentation. ill be waiting for more videos.
Wow! That is amazing! Very interesting topic, liquid rocket engines seems like a very complex thing 🤔 Looking forward for next video!
PS. Thanks Joe for bringing me here!
This video is so good I subscribed before finishing it
Love the vids keep it up and would love to see more like these.🚀
I’m 15 and making solid propellants for my rockets. Making a liquid fuelled engine is definitely my next project once I have a bit more experience with liquid propellants...
a lot more experience 😄
Excellent work Charlie , looking forward for your videos on how to design a combustion chamber and nozzle for liquid propellant rocket engines
We will watch your hobby with great interest.
This video made designing an engine incredibly simple! New subscriber :) I'm *attempting* to design a 3D printable rocket engine that won't melt. Easier said than Done!
If/when I get back to college, I want to eventually design and build a ~1kN MethaLOX engine, so if you don't mind I'm gonna be taking some serious notes, so if you want to go beyond the layman's explanations into truly nitty gritty masters details, please do cause I'm gonna need all the help that I can get to have a basic head start before I get back.
I don't talk about it here, but I did design work on a 2kN methalox engine. Machined a lot of test parts, but we had problems with supercritical methane injection, cooling, and generally inexperienced choices made early in the design. I'll throw deets in later videos.
@@dingwon Share the resources!!! I'd love to check them out!
@@dingwon Hi, is this offer still available? If you could share your resources that would be greatly appreciated.
If you're still interested, i've found using NASA's CEA ( cearun.grc.nasa.gov/ ) on the rocket mode will tell you almost anything you want so long as you spend a bit of time figuring it out.
@@robbiejames1540 Thanks for the link, I've bookmarked it! Unfortunately I'll be putting any return to classes plans on hold until the pandemic ends, but I've been gradually learning basic and above basic equations and concepts I previously hadn't learned yet. If I can learn some thermodynamics and become more acquainted with it as pertaining to the gas laws, I could potentially design a simplified rocket engine, or at least familiarize myself to the equations for one, before I make any real plans.
How do you purpose to deal with heating of the combustion chamber and the nozzle. Thanks if you have time do you have time to talk to a old guy about a few ideas
Yes, we are very interested in the more in depth videos!!! Load me up with plumbing footage!
Thanks bps space for recommending this video, very cool!!
Definitely interested in both more and more in-depth content!
Make more lectures on how to stable rocket....and all about rockets from starting
Hi Charlie. First of all, thank you for sharing your knowledge with us. It's really great to see other rocket engineers ideas. But I believe I have found some error in your calculation of enthalpy of formation. 2:01 From WIKI (en.wikipedia.org/wiki/Standard_enthalpy_of_formation ) enthalpy of formation for C2H5OH -277.0 kj/mol H2O -241.818 kj/mol CO2 -393.509 kj/mol. As far as I know, enthalpy of formation 3*(-241.818)+2*(-393.509)-(-277.0) = -1235.472 kj/mol. If I'm right, for 1mole of ethanol 1235 kj of energy is released. Feel free to correct me if I'm wrong. Again thank you for making this video. bye
Normally, you'd be right! However there's a phase change or two to remember, since we'll have liquid reactants and gaseous propellants.
The other secret is that software does this now-a-days with much higher fidelity because it can consider reactions that don't run to completion, and disassociated products in the exhaust stream.
Nomenclature; correct me if I’m wrong, but c* is typically used for characteristic velocity, c is exhaust velocity, not the same quantities (c* isn’t even a real velocity)
2:44 does anybody know how he gets to 3030K here? I only get something around 7000K, and when I use high temperature values for cp, I get to slightly above 4000K. So I must be making a mistake somewhere
Pls do more of this... I love it
4:28 I'm confused as to whether you crossed out the pressure of ambiance, or both pressure of exhaust and ambiance. Can someone elaborate?
Spacex interviewer- what projects have you done
Him - bulit a liquid fueled rocked
Can you tell me how did you calculated combustion temperature and exhaust velocity didn't get that 😭
Wow you deserve a LOT more subscribers!
This is going to be exciting
I'm so excited for more! Also promise me if you get it to work that you'll put a marshmallow coated in phenolic ablatives into the exhaust and attempt to roast it
Small question. Have you read "Ignition!" by John D. Clark? if so do you recommend it?
I have, and I do recommend it!
@@AstroCharlie Awesome! thanks for reply!
Great information. Thank you Charlie
could you put a link on all of your equations cause i am using different prepollents
Follow his lead and build a small one first, not like me who try'd to build a 5Kn engine right away. Short version I ended up putting the 5Kn on hold to build (and now done test firing) a smaller one first.
Stoked for more content! Good luck.
Can't wait to see more
My parents forced me to become doctor but want to become space scientist
You are lucky man
What are some yet unbroken records regarding amateur liquid fueled rockets and what have already been accomplished?
What did you put in ∆h plz reply 🙏🏻
if anyone is still curious on how he got all these values on his calculations, learn to use CEA. trust me, there is a LOT of things going on behind the scenes adn unfortunantly he does not go into much detail at all on how to do this yourself. this is just a intro. read RPE and do a little CEA and you will be able to get similar numbers to what he got. best of luck
what do you mean read RPE?
@@Outsoldier hello man, RPE stands for rocket propulsion elements, from Sutton. It has been a year since I started my rocketry project and I also recommend RPA which stands for rocket propulsion analysis. Super useful program. Currently writing a journal of how to make a rocket engine step by step, so if you are interested drop by my channel at some point for it. Unlike most videos on TH-cam I will publish my project to the public as a open source project so that anyone can replicate it and modify it. I also plan to make a discord server for people such as you and me to share their knowledge in a centralized place without the fear of being gatekeeped out of the hobby. Have a nice day.
@@astraeides11145 sounds really cool! ill keep updated on your channel and the discord server sounds like a great idea thank you!
Excellent video with great info.
Hi Charlie ! Thanks for your great explainations about Rocket engines
But I've tried many times to calculate an adiabatic combustion temperature, and every time I get a crazy value like 5000K, and you got a decent value here, how did you do ???
What values should I take for DH, and the heat capacities ??
Thank you Charlie, very cool!
SAW YOU AT THE BPS.SPACE LAUNCH TODAY!!!!!!
Get back with me about this, I am a planetary scientist but always enjoyed rockets
Any recommended books to learn about this kinda stuff? I'm in high school rn and I really want to learn! I don't care if they're technical or involve some math as long as I can mostly understand them :) 📖
Highly interested and worth the wait
Dude you are a master! Now build a simple a powerful Pulse detonation engine that could power a small aircraft or something like an Ekranoplan.
More video please please please, don't worry we are curious about detsils it wont be bored 👌🏽
Hello, im working on a 1.4kN liquid rocket engine for a high school project. My calculations somehow led to a very long combustion chamber. Could a longer combustion chamber lead to more instabilities or somehow endanger the engine itself. From what i know, it just loses its energy.
We'll talk about combustion chamber design in a few weeks, but especially for small engines, the chambers look disproportionately long in order to get good combustion efficiency.
Hey Charlie, at 1:59, when calculating heat released, 1145 kJ/mol is the enthalpy from the reaction, right? I saw from another site that the reaction of ethanol with LOX is 1368 kJ/mol instead. Is there a reason they're different? Am I looking at the wrong value on here - www.ausetute.com.au/heatcomb.html? Thanks! Awesome series!
I don't explain this very clearly, but my fuel is only 70% ethanol to help control heating, hence the lower enthalpy of combustion.
how did you get Cp of co2 and h2o because from what i see it changes with temperature and you cant calculate it without so did you just use a prediction?
How did you get 32.25 megajoules/kg? If 1000 grams (1kg) of propellant were used(oxygen included), 32 percent by mass would have to be ethanol. In 320 grams of ethanol, there are about 7 mols ethanol. 7mol times 1145 kJ/mol is 8015 kj or 8 mj/kg propellant. Even if you burned 1000 grams ethanol in excess oxygen, it would only equate to about 24 megajoules. Maybe I’m missing something?
I think his calculations are using 70% Ethanol, the rest being Water. That is where the 1145 kJ/mol comes from, undiluted it is around 1365.5 kJ/mol.
I think the math should be: 1000g * mol/46g = 21mol ... then ... 1248kJ/mol * 21mol = 26208kJ = 26,2MJ
@@theredstonehive where did the 1145 come from is it on a thermodynamic table for ethanol specifically?
alright I want to make one
but
I want some books about it first so I can understand all the equations you used
also where did you learn what you to make this engine
if there are books
can I get the names and links
is this pretty much the only type of it's video
especially with LOX
Could you please elaborate on the specific heats when calculating the combustion chamber temperature?
^^ Did you ever figure it out?
Pleas go more in-depth this project is great and introduces the laymen to basic design principles it’s really interesting.
Wow Charlie reached 1k subs!
I’m so glad I found your channel! I’m going into my sophomore year of college, and have a similar goal (rocket engine build) I want to reach by graduation. Based on your injector design, I’m guessing you already know about them, but I recommend checking out Copenhagen suborbitals. They walk through a bunch of cool stuff (not just the propulsion system, but....) and they really got me interested. Also, could I ask what books/videos you primarily used to get started? (Unless it’s all from class)Thanks a ton, and can’t wait to see more!
Isaac Davanzati
Hi Isaac, I'm quite familiar with Copenhagen Suborbitals, I was quite inspired by them myself back in the late -oughts (jeez I feel old...)
MIT's class notes are linked in the description. For texts, I used Huzel and Huang's excellent guide on small rocket design and Sutton's Rocket Propulsion Elements to start.
Ok I need a workshop, some materials, ethynol, LOX, and a test stand. I am actually curious tho, my friends and I are designing a rocket and I was wondering if I should use a hybrid or liquid fueled engine. I’m aware of the pros and cons of both, I just want a 2nd opinion.
For the equation C*^2/2 = CpTc, does this consider pressure increase from released gasses? Is pressure increase negligible or does it somehow get factored to the derivation of this expression, in due to using Cp instead of isobaric specific heat?
Would it not be possible to use ke = mv^2/2 to estimate characteristic velocity, using entropy in addition to enthalpy, to get an estimate of best case conversion from chemical energy to exhaust velocity?
i have a question though , is this just a lab model to look at or it has enough thrust to weight raio to support use
What is the size of the nozzle diameter relative to the size of the engine diameter?
Great video, I'm excited to see the rest. I'm also working on building my first engine this summer. I've decided to code all the nessecary equations in Matlab so that I can optimize them faster and compare other design choices on the spot. Do you have any experience with Nitromethane? I've read about it being used as a monoprop and I'm interested in trying to use it with Nitrous Oxide although I'm prepared to switch to another hydrocarbon for my fuel if my calculations push me that way. Also hoping to use a pintle injector with face shut off. My goal is to iterate until I have built a fairly reliable engine that I can then use to test other ideas that I have.
I'm curious what you plan to optimize for. Especially for the first engine you build 'robustness' is usually the most valuable quantity, but there isn't an equation for that. I've heard of nitromethane being used as a monoprop in torpedos, but I'm not super excited to go and try it. In a biprop, there are cheaper, higher performance, easier to obtain, stabler fuels, and even some with all of that in one.
When solving for the temperature of combustion, how did you find delta h? I get finding specific heats and your initial temperature, but I can't figure out how you found your change in enthalpy?
^^Did you figure it out?
Can you suggest some good books to learn these things in depth. Plzzzz
How did you get 3030K, I just can't get to that result?!
Very nice! Can´t wait to see more!
How are you planning to make the engine?
Will you just machine it out of something like steel, copper, or graphite?
Hi Charlie, thank you for your videos. Is your equation for exit velocity for choked flow only? Then I assume you wouldn't have a divergent nozzle? I ask because the equation NASA gives for exit velocity = Exit Mach * sqrt( Gamma * Gas Constant * TempExit ).
What value for T(o) do you use? And I'm assuming delta H is your 32.25 MJ?
I love your videos. It would be better if you get a microphone
hi! does regular comprssed air work as oxidixer, and if not where can i get the nitrous? thank you!
I don't care if I get hurt at Least I'll die doing what I love
Can we use liquid propane for propellant
yes i would believe so just follow the process he did in the video and it should work
Can you please tell me which solid fuel is used in rocket
Where can i find a references book for design a rocket ?