A Primer on Nuclear Rocket and Why They're Awesome in Space
ฝัง
- เผยแพร่เมื่อ 15 ต.ค. 2024
- Want weekly Vintage Space? Subscribe! / @amyshirateitel
There's more on Nuclear Engines and NERVA in my companion blog post over on Discover: • A Primer on Nuclear Ro...
Thanks to Scott Manley and Matt Wood for double checking my nuclear description on this one!
And more even older space in my book, BREAKING THE CHAINS OF GRAVITY! You can order your copy on Amazon: bit.ly/astbtcog
My blog archives has lots of awesome olde timey space, too (and I'm looking for a new home for it, too!): www.popsci.com/...
I've also got a PATREON PAGE! Want to listen to a Vintage Space Podcast or get awesome merch like t-shirts? Please consider becoming a patron! I've set up a Patreon account so I can raise funds to buy the gear I'll need to make an awesome podcast and also work with professionals to make better content all around. Any help is so hugely appreciated. / amyshirateitel
Connect on Facebook: / amyshirateitel
Google+: plus.google.co...
Instagram: / amyshirateitel
Twitter: / amyshirateitel
Amy thank you I have missed you very much and have always enjoyed your very informative videos. I always wish you and your cat the best be safe be happy and I look forward to your next video.
That little giggle at 1:30 in context of what you are saying ... PRICELESS!
Finally understand what specific impulse is now. Thanks Amy!
I hope this helps! We all know I'm not actually a rocket scientist, but I feel like I finally got my head around it!
I usually just multiply it by g and get the propellant velocity at the nozzle.
I saw explanations on other channels, but Amy's explanation is by far most clear and easiest to understand
Isp is relic from time before electronic calculators (it simplifies calculations). Even today it has advantage of being same in all unit systems. But in physics it is incorrect.
Impulse = force*time
specific impulse = force*time/mass (mass of propellant used in time)
This has unit of speed. So to get specific impulse from Isp you multiply with g. In this case you have to use 9.81 m/s² even if rocket is on the Moon.
They got Isp by using same unit for mass and force and canceling units away.
@@jkn6644 I think the seconds comes from the following. if you measure thrust is kg-force, its how long an engine can burn on the amount of fuel in kilogram as its thrust in kilogram-force. so if an engine with 40000kg-f or 392.266KN can produce 40000kg's of force with 40000kg's of propellant for 311 seconds, it has a specific impulse of 311 seconds.
This might be your all time best video (with the exception of your awesome Pluto videos, your great Apollo videos, etc). It is great to have you back. Seriously though, I was going to say that this video is so good it puts you back up to where you were when you were on par with Scott Manley, then I saw you give him credit for helping so I'm not sure how I can compliment you on how good this is. I'll have to bump up my patreon pledge!! You guys are both top notch!
Welcome Back! - I look forward to getting to your book on my Kindle list. BTW, Nice Gemini Rogallo! I don't think I'd noticed that before.
I'm from Brazil and love your knowledge in space's history. But rarely a have seen a video so deep in tech in your channel. Impressive.
2:04 The CSM Engine didnt use Hydrogen, it was hypergolic N2O4 / Aerozine 50, the 5 J2s on the second Stage and the one on the SIVB used H2/LOX. Im sure amy knows this, but the animation department made a whoopsie.
The CSM did use Hydrogen for the fuel cells, but this is obviously for power generation not propulsion. Probably why they mixed it up.
Love the quality of the channel and your delivery. You make it almost seem simple ... not an easy thing to do at all.
Welcome back! Missed these!
Nice description, Amy. Thanks!
Great to see you back on the air with more fantastic retro space info! Nuclear rocket propulsion is probably my favorite vintage space tech.
Very happy that you are back Amy. Big hug for you and Pete.
glad to see you back Amy. I missed your videos
thanks for coming back to enlighten us
Beautiful Amy is back! Now I can binge on sci news and history again.
Amy, you're a treasure. Thanks a million. Per Aspera ad Astra.
I think I know this one... "Through adversity to the stars"?
(I know I could just google it, but that's no good for winning at pub trivia!)
This was a great explanation of specific impulse. It's way simpler than the mental model I was using before. Great video.
It's so nice to have my favorite Canadian space nerd back on TH-cam. I've missed your videos.
I really do mean this in a good way. You make the topics you cover entertaining and easy to understand. *:-)*
I've missed her. Wherever she's been, I'm glad she's back!
1:19 That oversimplification is an understatement! (But a very good one, Amy! :) )
Great that you're back on screen again! Thumbs up, and best of success with your new book
In my original timeline we went to Mars in 1981. I wish I could get back.
Welcome back, Amy. When I first saw the title, I thought this would be about Project Orion, which my friend George Dyson wrote about. It is the atomic spaceship his dad Freeman Dyson worked on in the late 50's that would use nuclear explosions to push the vehicle forward, but that the Partial Nuclear Test Ban treaty put an end to. Your explanation of NERVA and specific impulse is just as awesome. Thank you for resuming your Vlogging.
I’m over here excited about her Civil War book collection by Shelby Foote.
So glad to have you back! Can’t wait for more videos!
Hey lady where have you been? What’s all this about another book?
Great to see you’re making vids again!
She must have found a boy friend or something.
She was writing a new book.
Chad Vader 😭
@@dcanaday Please don't Destroy my Fantasy like that!!!😭😢😭😥
Just finished your book! It tied together lots of issues and happenings from that era that I knew something about. Many history holes have been filled!
You're a great presenter, and I hope you eventually cover the array of experimental magnetoplasma rockets.
Korolev wanted for his interplanetary ship an Ion nuke engine. Nuke reactor supplying an ion engine.
Thanks for coming back. I missed this channel.
Great video. Also took your recommendation and saw Apollo 11. Really a great movie.
Stephen Crawford: you should have seen Mercury, Gemini, and Apollo 13!
Great to have you back. Can't wait for more. Thank you.
Yay new vintage space!!
Thought you were going to talk about Orion engines for a minute. Still cool though.
Orion is neat, and a segment on "nuclear salt"/water rockets would be mindblowing. Isp in the THOUSANDS.
Great to have you back, Amy! Really interesting video.
So while I love vintage space, I do have to disagree with the explanation given here.
What governs rocket propulsion is momentum exchange so having a faster gas exhaust speed with a lighter gas (ie hydrogen) doesn't necessarily give you more thrust, as for Isp, it is purely based on the exhaust speed and not the mass of the propellant!
To achieve that high exhaust velocity, we heat and pressurize the gas and then use a convergent divergent nozzle (or de Laval nozzle) to accelerate it, whether you use a nuclear or chemical rocket!
The reason a nuclear rocket engine is much more efficient (Isp wise) is primarily due to how you achieve that high temperature and pressure! You are using fission which is has much higher power density than a chemical reaction! This is why a nuclear bomb is such more destructive than a chemical bomb!
Since the energy density of the chemical reaction is much lower, this is the first reason of the Isp difference. A second one is directly linked to the chemical process, in a chemical rocket, the pressure required are so high that the chemical reaction time is equal or longer than the time the fuel spends in the engine, so you do not actually use all your fuel! The big flames you see is what the engine waist! This is why hydrogen fuel is the best rocket fuel today, not because of its mass but because of the kinetics of the combustion, hydrogen has a much faster reaction time than fossil fuels so you extract proportionally more energy from the fuel that you can use before you eject it out of the engine.
Finally, the primarily reason of the use of hydrogen for the fuel in the nuclear rocket is due to its thermal properties which optimize the heat transfer through the reactor! The key part is getting the gas as hot as possible! Even with hydrogen, the NERVA designs were planned to produce about 5 GW, which would make them the most powerful nuclear reactors in the world. If it was as easy to heat up a heavier gas we would do it as we would generate proportionally more momentum.
Basically, it is a fight between splitting the atom and stealing electrons!
SoldatInconnus
Exactly. We’re still a Slave to F=MA. If the exhaust gas is lighter it HAS to be faster to generate the same thrust. Now with the nuclear engine, you can run it longer so...
And something a bit more unheard... How to repair an engine that becomes radioactive?
Ultimately tho you are temperature limited and the lighter hydrogen atoms are moving faster, at this given limit right? A heavier gas has a lower Isp at a given temperature and reactors will melt if allowed to get too hot. This is why other ideas like the gas core reactor are proposed. Solar thermal uses hydrogen for this reason and can achieve over 1000 sec. as opposed to the 800 plus of solid core nuclear reactor rockets using a rhenium heat exchanger (at lower thrust and for in space use only but at a tiny fraction of the cost).
It DOES matter having a faster gas exhaust speed with a lighter gas, being lighter means that you can load more with the same mass. So in the end you will have more thrust for the same weight
@@stevemickler452 dear Steve, in the Nuclear rocket, you are not temperature limited but energy limited (big difference), which explains this. You prioritize the the gaseous element that can best transfer the heat from the reactor to itself so that you can extract the most energy, which here is in the form of heat! And again, heat transfer is mass dependant but much more dependent on the specific heat, it will take 10 times more energy to heat up 1kg of water than 1kg of iron! Hydrogen's thermal conductivity and specific heat in the gas phase is greater than any other gas and this is why you pick hydrogen, combined with the fact that it is the most abundant element in the universe means that it is the one element where you could imagine space refuelling.
As for the Isp, the reason the heavier gas has a lower Isp is because its thermal properties are not as good as hydrogen! Ve is directly dependent on the gas temperature and the mass but specifically on the isentropic expansion factor (thermal property) which influence the much more the exhaust velocity! At equal Isp, it is better to have a heavier gas. Whether you want to look at it from the point of momentum or thrust, the total momentum is p=vm and the thrust is T=v*dm/dt so it means that if your gas is twice lighter, you have half of your thrust but the same Isp! Which means now that your tank is twice bigger and so your rocket is much more bulky and heavier to send the same payload into space! The MAIN reason hydrogen is the best is because while you have the mass as a factor, the thermal properties influence much more the result of the thrust, more than the mass and compensate for the smaller mass of hydrogen!
Very good explanation, extremely clear and easy to follow.
Great to have you back!
A nit pick: the beryllium jacket is a neutron reflector, it prevents neutrons (not heat) from escaping, and so sustains the fission reaction. The control rods are boron on one side and beryllium on the other. Again, the boron is absorbing neutrons: the amount of neutron absorption is what controls the reaction, not the amount of heat absorption.
The rotating control rods were less likely to get stuck than linear control rods, at the temperatures these were run at.
Heat does have a controlling effect, in that thermal expansion will reduce the fuel density and so increase the critical mass and lower the reactivity, but this was not enough to save one of the experimental models, which ran out of hydrogen, blew up and spread itself over the Nevada test site.
Kevin, thanks for the details. I thought the beryllium jacket was just a high-priced fashion statement. 😁👍
Thanks for sharing that tale of Jackass Flats. I was going to say: Cooling rods or Control rods? You explained it well!
Glad someone caught those details.
Another sciency question. The application of the word "weight" when referring to the exhaust gas has me confused. I think it should be mass or density, but I'm not sure which. Any thoughts?
Molecular weight. Hydrogen gas has 2, water has 18, the lower the molecular weight of the exhaust gases the higher the isp.
Thanks for your efforts, always of interest.
Wow like old times!
(hey Amy your Insta link doesn't work : )
neither does the twitter link
Thoroughly enjoyed this as usual and so great to have you back!
Excellent video, and thank you for not being one of the hysterical "OMG NUKULAR!!!" folks that reject this much needed technology. If we are to colonize Mars, we will have to employ nuclear power in the process.
*"Nuklar **_combat, toe-to-toe with the Rooskies."_** -- DR. STRANGELOVE (Or: How I learned To Stop Worrying And Love The Bomb) [1964]*
😊😊😊
SHE’s BACK!! For REALSIES! Awesome.
This is the stuff I want to get a Ph.D in. People scoff at wanting to combine rockets and nuclear engineering! Ahaha!
They just haven’t tried hard enough yet
That's the kind of comment that should be followed by :"I'll show them, I'LL SHOW THEM ALL!"
@@TheStephaneAdam you forgot "Muahahahahahahahahahahahaha!"
My uncle is involved in the design of a fission rocket engine. If you are interested in this you should look at working with or at Marshall space flight center in Huntsville Alabama.
1320crusier nothing specific. Heat rejection is still a major problem.
Very interesting and really well explained and finally, someone that explains impulse so simply - my Kerbanauts thank you.
Love learning new things in The Vintage Space Classroom......I left an Apple for The Teacher! Cheers From Ohio...Home of Wapakoneta
🍎
Ohio is also home to Dayton, the Birthplace of Aviation... and the late John Glenn... and the NASA Glenn Center in Cleveland.
note to Stuport… yes, home to Wapakoneta but, just fyi, Mr. Armstrong let his official biographer (Jim Hansen) know he always considered Upper Sandusky his hometown as that's where he did most of his growing up in the Buckeye state...…...
@@richardmourdock2719 I knew this fact! I was just being cheesy in mentioning this City! GO BUCKS O-H
@@ChristopherUSSmith My Dad was a 33 year man in the USAF and we went to Wright Patterson every year for the Air Show and to sight see in the museum! Really cool adventure! Cheers
I'm glad you're back; thanks for all the great stuff! You explain things well, quite understandable.
At 2:30, “Tyranny of the Tsiolkovsky Rocket Equation”.
That sounds like a movie! 😀
Basically that states that the pressure of the propellants entering the combustion chamber of the rocket engine must be greater than equal to the pressure (but not the total power) of the rocket exhaust
Ironic that immediately before Amy's Vid I got an advert with Chris Hadfield sta[r]t[t]ing:
"The rocket equation - it's a beautiful thing...."
Um...._weeeeelll_...
The Rocket Equation is what it is, there is no aesthetics to it
Such a cool engine concept. Loved this one Amy!
Could you do a video on what would happen if the Saturn 5 rocket exploded
Think small nuclear bomb.
@@randomworld1 yeah but I still want to know exactly besides no one has looked at this topic trust me I checked.
🚀💥😱
@@jonathan-rm4sk If a Saturn 5 exploded (depending on mission stage) it would kill everyone around it. This never happened though in a mission, thankfully. This is part of why there is an enforced radius away from the launch site during launches. Well, that and the risk of people going deaf. The Apollo command module (which had the astronauts in it) was equipped with its own launch escape system in the case of a serious Saturn 5 issue. If 2 out of 3 wires that ran all the way to the base of the rocket during launch lost power, it signified that the booster was coming apart, and a small rocket on top of the module would fire, lifting the module off, and the module would splash down.
@@SweetBearCub yeah I know why they built the launch pad that way I'm not dumb I'm just curious what would happen if it did like what would the blast raiders would be how powerful it would be and how deep a crater it would make stuff like that because no has done a topic like this before trust me I checked.
Yeah!! Welcome back! And teaching on day 1 - I never understood specific impulse before, thanks Amy
Hi Amy welcome back! Apologies for being pedantic … but … the Beryllium reflects neutrons not heat and the Boron absorbs neutrons thus shutting down the reaction. I guess to the extent that the neutrons are able to transfer heat this could be correct, but in the strictest sense it is not. Also technically they are control rods not cooling rods. But wait perhaps that explanation was part of the vintage video you displayed and who ever put that video together “dumbed it down” for public consumption.
Anyway … welcome back!
Aah, but are they thermal neutrons?
Rob Speed that’s a hot question
@@christianbergman711 Gotta think fast!
Rob Speed you show good breeding
I'm happy Vintage space is back.
I work in the Space Biz, but I always learn something new.
I work in a Biz Space. Commonly called a cubicle.😵
That's really cool! If you don't mind me asking, what do you do exactly?
Welcome back Amy! Interesting and informative as ever.
NASA: "We want nuclear rockets"
Russia: "We want nuclear bombs"
*CONSPIRACY MODE ENGAGED*
Russia: "We have nuclear rockets!"
NASA: "We need to make nuclear rockets great again!"
Soyuz New 3rd stage is monopropellent with amazing thrust, nuclear or plasma?
love the exclusive use of vintage graphics 😁
Welcome back Amy!! Nice re-starter video!!
Great info. Welcome back. Keep the videos coming.
Amy, great stuff! You may already be aware, but there is a guy named Kirk Sorenson who talks extensively about the Nuclear Rocket Experiment and now its possible application to a molten salt reactor fed by Thorium in a liquid beryllium blanket. His Protospace video at Calgary is a little long (2 hours+) but fantastic and I think you will find a kindred spirit. He was also a NASA engineer for ten years. Thanks for all the terrific history. Capt. Mikey
Excellent video, especially the great explanation of specific impulse. Amy, it's great to have you back!!!
So glad to have you back!
Great video.
Another great informative episode. Thanks Amy!
Speaking of retro space. I just watched an old 1950s movie cold destination Moon. This film portrayed everything that you have discussed. It won an Oscar.
Probably your best video to date. A well-matured presentation. Thank you!
Yay!!!! So glad to have you back Amy!
Welcome back. Loving the use of the old school explainer videos.
(in a tone of astonishment) Aaaahhhhh! Finally an explanation on the workings of a nuclear rocket engine. Thanks Amy! The animation for the explanation was well done, too.
I live in Nevada, and on occasion, a local PBS program will talk about the Nevada Test Site, and briefly mention about the nuclear rocket testing done out there. But, it left us TV viewers puzzled how nuclear fuel was utilized to create such propulsion.
Didn't know @ NERVA, or Werner Von Braun estimation of Mars mission in 1981. Or anything in this vid. Vintage Space = Rock n'roll. I ♡ Rock n'roll!!!
Another great video! Great to have you back!
The new wall colour looks great, hope renovations are going well
Well presented and explained, as always. A few commenters have pointed out some small technical errors, but they are so minor as to be insignificant in the broader context of the video. Welcome back Amy, looking forward to seeing more interesting content from you!
I'm glad to see you're back Amy. I just found myself wondering 'Do Amy's friends roll their eyes every time Amy mentions space at parties?' Keep up the great work and well done for publishing your book.
Great to see you back! and I like the new channel graphic at the beginning of the episode (very 1960s vintage).
Kind of a "My Favorite Martian" TV show look and feel to it. I like it too. 🚀👍
Best episode yet! Loved this one!!!
Glad for more Vintage Space! Great content!
I’ve been missing your work! SO nice that you put a new video out there! Thank you, very much!
Thanks for this. So very good to see you making videos again. :)
Something else I appreciated about this video: It explained the simplicity of chemical rocket fuel. And I bring this up since I can recall in TV dramas and movies in the 1960s, a re-occurring plot for espionage would be a scientist involved in developing a formula for rocket fuel . . . where it gave the viewers the impression that to create rocket propulsion, a complicated, and exotic, blend of chemicals were needed . . . and not something that could be whipped-up in the kitchen of a farm house . . . after all, in rural areas, kerosene was needed for lamps when electrical outages happened. Ah! But what about LOX? Well, farms I'm familiar with do have bottled oxygen for welding/torch cutting purposes.
I learn so much from this channel, thanks a lot!
So good to see you again. Waiting for details about your new book :)
Good to see You again!
Gladly watched a commercial for you, Amy!
It's great to see you back. Thanks for this cool video. I even understood it!
Glad your back - make a show explaining how the crawler worked - moving satern5 - no one has really show how rocket was removed from it
Great video! Thoroughly enjoyed this.
Wow. I always wondered how this type of engine would work. Thanks Amy
Welcome back Amy, I missed your great videos!
Was wanting to hear about this and lo and behold you had this great video. Perfect..
Really interesting video. Glad to see you back!
Quality video Amy.
Thank you.
This is the stuff I come here for! Thank you for the information, had never heard of the Nerva program ... very cool
YAY welcome back Amy I've been missing your great videos!!
She's back! Was bummed, not enough good space channels like yours.
Just found this channel and I already love it and possibly you lol, but seriously great channel so much info that you pass on in a fun and unique way, thank you.
I learned so much from this video. Really amazing.
Where have you been? Great to have you back. Most informative.
Welcome back Amy! Have missed your videos while you were gone and looking forward to reading your new book!
It's great to have you back.. missed u a lot😍😍😍
Thanks for the lesson Amy. I enjoyed it very much
Happy to see you back, Amy!
It's nice to see new content on your channel.
Welcome back, Amy. We missed you.
Love these videos.