Rocket Stability

This episode discusses the stability of fin stabilized rockets. It includes multiple swing test experiments to verify the location of the Center of Pressure determined by two different estimating methods. This video is intended for high school teachers and students.

[@bcdefg]

can't tell you how good it is to see videos like this on youtube - no fancy graphics or ADHD humor, just straightforward info. great work

[@spamcan9208]

It's very refreshing. Just the facts.

[@Xhampeion]

I would agree but I do also like picture models/blueprints and real models.

[@arnie8958]

Lmfaooo ADHD humour😂😂. You a legend

[@waiqiao6875]

Agreed

[@hollodollo4771]

"ADHD humour" dude adhd is a condition that people dont choose. You can jus say chaotic you don't need to be insulting about it.

[@BristenBourque]

Just watched this with my 11-year old son. You did such a great job explaining the concepts! Thank you so much for sharing :)

[@gastonbarouille767]

Best teacher I ever saw on YT! Few resources and tangible explanation makes invaluable information transfer to everyone! Thank you so much for sharing!

[@sushantasharma3415]

Great Video, did a very good job on explaining rocket stability concept to the people who are new to rocket science.

[@OngoGablogian185]

The slow-mo of you swinging the cylinder around your head was Hollywood-level. A true work of art. You looked like a majestic and benevolent lion, taking a well-earned day off from mauling zebras to enjoy a day in the park.

[@hoytvolker3]

Very informative and logical, now even a 10 years old can understand due to your good way of conveying the info.

[@nikrous5996]

You did the best for us. You are exact and clear on what you say. The method and the way you use, ,makes everyone to understand too many things in a such short time, in the most theoritical as well as in practic way. You are superb.

[@anajuliahirata7783]

That's true. You know how to explain is a easy way mixing hard tasks with easy ones

[@muhittinselcukgoksu1327]

Thank you so much. I am a retired statics lecturer. Your explanations are beneficial to me.

[@Mephora]

A bit too simple for what I was looking for but I feel like this is one of the best introductions to rocket stability I've ever seen. Loved all the little props you had to illustrate Forces etc

[@lawrenceh5354]

Wow! I've been wanting to get into rocketry for awhile and watched a bunch of videos about it, this is hands down the best. Straightforward and easy to understand. THANK YOU!!!

[@lautarocardozo9921]

perfect for playing KSP

[@leonidkhamadakov7778]

Lol yeah

[@RICREYNOLDSMUSIC]

I am a distant relative of the Lee family from the same area. Most of my family on that side lost their lives in Coal mines. I have fought, starved, and survived that life to work in the aerospace and military supply area. I was on the Trident missile program and Raytheon missiles. A late starter at age 32, I am a living example you never give up and fight until your last breath. I am now with a a break-off company from Raytheons best inventors to help with innovation and new future ideas. We are part of our ancestors and though we improve on those characteristics, we should still be thankful for the sacrifice they made.

[@Omar_P.S9inchhs]

I'm making a paper plane for my nephew that's why I'm here...his brother refuses to make a paper plane for him and he asked me and I promised him a paper plane that make his brother jealous...I watched this video and I made the paper plane...I'm still playing with that paper plane myself!...this flying capabilities are amazing!...and I'm starting to get interested in rocket science...and yes this thing is absolutely gonna make my nephew happy and more importantly make my older nephew his brother jealous because his paper is barely flying 😂...Thank You very much this was a great demonstration.

[@embergamedev]

I have watched so many videos just getting into the hobby. This is by far the most detailed, enjoyable, and intuitive video on the topic I have watched so far. Thank you! I am excited to try all of these tests for my own model rocket!

[@gustavo1995gugu]

Sr. You were born to teach! I wish every teacher was like you. I thank you from Brazil.

[@paulorocha7801]

Congratulation. This is the best explanation i found in internet.

[@capcloud]

This is a crazy good vid. Thank you from a Aerospace engineer.

[@titusrider7948]

Excellent video lesson ! Not only a great video on what is center of pressure but also why it is important to the flying characteristics 😊

[@mybluemars]

Beautiful video! Good stuff here! Thank you!

[@klebao9515]

wow, amazing video, a hug from Brazil!

[@therealaim-9xmissile]

The way he explains these concepts in a simple straight to the point strategy is a god send for stem students lol

[@jodigant]

Thanks for Wonderful video, I am a teacher and I teach model rocket to school and college students. I always love to enhance my teaching methods,and this video surely help me lot. Thanks again.

[@yevgeniygorbachev7289]

I love how concise the presentation is.

[@ahmedosama7463]

I loved this explainer, without fancy graphics nor music, i did really learn from it, amazing one, keep doing more like this one

[@dagon86]

This is the best video about rocket stability on youtube

[@anajuliahirata7783]

I really liked you videos. I'm from Brazil and with your video I could understand the center of pressure and how to calculate it. Thanks very much

[@notsecure6855]

Dude, you're awesome. Thanks!

[@rcytb]

EXCELLENT explanation. Thank you.

[@moroniafrifa614]

Wow! This is one of the best explanations of rocket stability

[@thephilanthropist5918]

If you places a fan about 2 or 3 feet above the cardboard cutout blowing downward onto the "shadow" and then tried to balance it you may find the center of pressure more accurately. The downward flow of air will create a greater force toward the rear of the rocket because of the greater surface area which means if you want to balance it you will need to move the fulcrum point further back towards the rear. Not sure of this would be more or less accurate than open rocket but I'm fairly confident it will be more accurate than the shadow method without the fan. Just a thought

[@lfmtube]

I just read the About on your website. Congratulations on all your accomplishments, and thanks for sharing your knowledge. I find your videos very interesting. Pure knowledge! Thanks!

[@biology789]

Very useful video Sir these kinds of channels are creating the next Scientist, Entrepreneur and the making kids ambitious about science, technology and space. ThankYou we all appreciate ❤❤

[@nonunga]

My right ear is sad

[@lucasrademaker286]

exactly

[@josephamalsabu]

Mine too 😁😁

[@greetingsgentlemen.8179]

lol

[@EricRobb]

I didn't even notice until I read this comment. LOL

[@busy_beaver]

Yes

[@niceguy5772]

this channel is so underrated , it deserves more subscibers

[@steffenleo5997]

Very well explained Video Sir... Thank you so much for these videos... 👍👍

[@edwardlecore141]

Brilliant demonstration, I wish I understood a word of it.

[@anajuliahirata7783]

Hi! I'm from Brazil and I loved your video, thank you so much

[@mexitechnology7838]

Thanks for this amazing knowledge. hope to see you here again.

[@edgarguinartlopez8341]

Thank you, professor. Rockets are a fascinating matter.

[@princedemiterios2488]

That's a very infirmative and educative ,all the best Sir , Thank you .

[@ekulda]

my favourite subject. rocket science. Thank you, i learnt so much today. what about fuel distribution. Weight pay.load capacity? great teacher you are Sir. simple and to the point.

[@thetransformatorium7980]

This is a great explanation and demonstration. For what it's worth, you just got another subscriber. Cheers!

[@stemmentor9700]

Of all the years building as a teen, and now moons later getting back into model rockets (79 my last launch). I only knew Cp and Cg but never calculated or had too. love the simple explanation and great to know there is more Open Source software (OSS) Like Open Rocket to help calculate I plan on starting from scratch again (bottom up) but will have a nice custom built and do these calculations. simple - informative and years later i know more then just Cp & Cg and the Cp had to be behind. I know why 👍

[@jarrodblankenship7546]

Was a little late to the show lol but i was recommend to watch your channel by a friend of mine, and man am i happy i did. just gained a subscriber!

[@adamprozak9409]

Great job on this video. Very useful and coherently and simply presented

[@andreytarakanov9879]

Вот что значит качественный и хороший лектор. Я ничего не понял, что он говорил (я не знаю английского языка), но я все понял что он показывал. Даже без знания языка, он доходчиво все объяснил. Молодец. Хороший рассказ.

[@kripton1312]

Ней Андрей как дела Я знаю турецкий язык

[@edenyanko9521]

A great video with a super great demonstration! The best I've seen. Huge Thanks!

[@joelevy6676]

Really outstanding! This is going to help me get my students up to speed.

[@thanoscube8573]

You are an amazing teacher. I'm going to use what you taught me in my bottle rocketry. Thank you so much

[@adelalshurbagy1113]

from costa rica , keep the great awsome informative works coming

[@panigrahi_industries]

Sir Absolute best wor in youtubei guess it was very helpful and wasas pretty straightforward

[@ProjectHub1]

love the chanel. Simply without a fancy camera

[@KumarKumar-fc2gc]

Just fantastic...!....your spin test was awesome...

[@emilkuban6978]

nice explaination. I like it

[@quebuenavaina]

excellent video , thank you to share your knowledge

[@e.g.c.8376]

Thanks for the video. Very interesting. Will watch your other videos.

[@sivasrinivash7206]

Great video sir. Thanks for effort you put in this video. I wish all our education materials should be digitalized in such a simple and excellent way as you did sir.

[@andrey-kramer]

VERY good video Unfortunately it is in English, not Ukrainian. But it is the only one disadvantage 😀 P.S I am extremely grateful to you for the video. During the war and mass rocket attacks of Kiev, I am interested in the physicist of the rocket flight. It would be super if you talked about navigation rockets in flight. And how to calculate the amount of fuel necessary for flight at a given distance.

[@dhoomketu731]

Beautifully explained

[@TheStephensonRocket]

Great video with great explanations of the concepts

[@jeffparisse4202]

Wow! You’re an excellent science teacher! Great refresher! Subscribing now...

[@ansterling522]

I understand now.yay!

[@meriquirogaalbarracin2420]

Excelente explicación..

[@RandomRoulett3]

4:16 I think the better explanation would be if you take the total cross-sectional area of the rocket and divide it by two, the dividing line would be the center of pressure. The drag produced on each side would be equal to each other.

[@miguelmouta5372]

Thanks for sharing your knowledgment.

[@arty5279]

My left ear really enjoyed this

[@steveinfrance6159]

I don't know if you're still reading comments so maybe I'm wasting my time ! Thank you for a well done explanation. There are a couple of things I've never understood about fin-stabilized rockets. Firstly you don't mention the effects of thrust. I believe the thrust force on the rocket will occur at the venturi (i.e. pretty much at the rear) and may not be exactly axial. The result seems to me like balancing a broomstick on your finger - that is it's completely unstable and I don't see how the fins compensate for that. The other, and probably less important, is that the CG of the rocket will change as the propellant grain burns.

[@labratscientific1127]

You are right, a thrust misalignment will cause the rocket to pitch (or yaw, or both) which could make it fly in big loops or become unstable. All rocket pitch, roll, and yaw motions act about the rocket's center of gravity. As the rocket pitches due to the thrust misalignment the fins take on an angle of attack to the airflow. This angle of attack causes lift to be generated at the back of the rocket which causes a moment (or pitching action) about the CG. Because of the geometry of the system, the lifting force is in the opposite direction of the slightly sideways thrusting force. As such, the motion due to the thrust misalignment is countered by the lifting action of the fins. If the fins are big enough and the misalignment is small enough the rocket wont actually pitch (or yaw) much and will remain stable. Now in an extreme case a huge thrust misalignment could overcome any lift generated by the fins - and the rocket would flip around and be unstable. The key is that the motion is about the CG in free-flight and you need to look at the direction of the forces acting on the rocket (lift, drag, thrust). Robert Goddard (the father of modern rocketry) had the same concern about the "broomstick on the hand" issue. Because of this he put the rocket motor at the front of his first rocket. It didn't' work too well and after that 1st flight he moved his motors to the back of the rocket and added fins... I guess he thought more about the forces at play. Finally, as the motor burns (in a model rocket for example) the rocket gets lighter at the back. This makes the rocket's CG move forward, which in turn makes the rocket more stable. Remember stability depends on the distance between the Center of Pressure (CP) and the Center of Gravity. If the rocket shape does not change, the CP position remains constant. This might not be the case for a liquid rocket since a lot of the fuel may be carried in front of the CG. I guess that is why we need rocket scientists - to figure out this stuff. Thanks for the question, I hope I helped clear things up a little.

[@steveinfrance6159]

@@labratscientific1127 Thank you so much for your detailed reply. I forgot to compliment you on your 'piece of string' technique when most folk would be thinking of a wind tunnel. It hadn't occurred to me that, although the thrust is pushing at the bottom, as it were, the force produced must act through the centre of gravity. That does explain things. I used to make large rockets (>1 kG) using PVC pipes and just pot. nitrate and BBQ charcoal. I was fortunate to have a 10 ton hydraulic press at the time so I could form a decent convergent-divergent nozzle and also pack the grain very hard indeed around a hole-centred former. I always used a stick, I'm afraid, but it didn't need to be that heavy and, I suppose, acted a bit like fins in terms of aerodynamics. They used to disappear out of sight in a most satisfactory manner but you had to watch out for them on the way down. I wish I'd seen your video then and been brave enough to try fins but I imagine they need a launch rail to get them up to speed in a straight line while a stick doesn't. I have a copy of Willy Ley's book in which he describes a live test firing of Rheinbote at Peenemunde witnessed, I think, by Goebbels. It was supposed to go off down range but the top fin caught on the launch rail and it went straight up. Ley describes how the moment was followed by frantic scrabbling on slide rules by the rocketeers trying to work out how long it would be before it came back down and if there was any point trying to run away. Came back down it certainly did but Peenemunde was pretty much a bog and it was travelling rather swiftly so it went many meters into the ground before there was a bit of a 'pop' and a wisp of smoke. Goebbels said 'If that was a real weapon we would all be dead', got into his Mercedes and drove off.

[@pauldegregorio5319]

Great video. One question: on a model (flying) rocket (like Estes), in determining the center of gravity, do you have the engine in or out (it can make a big difference)?

[@levibacon3740]

Thank you, this was a very helpful video

[@diiiaggl4513]

Simple and accurate, appreciated

[@Tamingshih]

Amazing , how clear it is!

[@BiancaDianaT]

Brilliant. Just, brilliant

[@sabercruiser.7053]

Outstanding job Sir much greatfull God bless you 🙏🤲👏👏👍👍

[@maxschannel8624]

This helped so munch! Thank you.

[@Mayur5_5]

You are amazing teacher

[@BourbonWhiskies]

How do we calculate the change in CG moving as the fuel is spent. "Find a happy medium". Or, should we account for this? Thank you kindly... By the way, this was a great straight forward video.

[@labratscientific1127]

I would usually design for the worst case, and that is when the CG is at its aft most position (i.e. when the rocket motor is full of propellant). Now, if we are considering a liquid fuel system, the CG could shift aft as fuel is burned depending on there the fuel tanks are located.

[@mostafaseif4409]

Thank you for this it's awesome!

[@shraddharajpoot160]

Very Nice Explainations very nice job sir dor the students

[@nurgulquliyeva7296]

excellent explanation! thank you so much :)

[@wizzardrincewind9458]

Thank you, I learned a lot. Greetings from Germany :)

[@b_rocket]

Thank you for your work!

[@Karno333]

Thank you for video!

[@x1101126]

This is true Rocket Science.❤

[@patriciocohen8081]

excellent video

[@samysalem8311]

Thank you very much, this was actually helpful

[@RidiculousRocketry]

Helpful information.

[@dronepilot260rc]

Very nice! I’m planning to make a propeller rc 🚀 rocket. Very informative video!

[@nm6381]

Great video

[@geraldozambrinjunior4667]

😀 vivendo e aprendendo!!!! Thanks for video!!!💯

[@analogalien]

Fantastic!!!

[@iagolira]

Great! Thank you!

[@emiryazicioglu1039]

so usefull, thanks

[@blockstacker5614]

I guess this is why they never fly rockets with no payload, even if they are just testing one they will put a big weight on top. Makes sense that they do that in order to avoid destabilizing the rocket

[@pingdopong]

This was explained so well

[@andrewferguson8485]

Very helpful! Thanks

[@rodrigopropp2214]

thank you it helped a lot

[@btrocketry3736]

Got my rocket design just right after 2 years of RnD..Launching vertically and landing them horizontally. No parachute required.

[@nickgraham6720]

Really good video, thanks

[@Gio_Grosso]

Thank you so much for this, I wasn’t sure what anything means on open rocket 😭

[@RahulKumar-gc7lc]

Great Explanation Sir..