The Amazing Engineering Behind Solid Rocket Boosters

[@Torjus_]

I wish documentaries were like this. Not the over dramatic dumbed down version we usually see. This is great, learned a lot of stuff I've never heard about anywhere else. Fascinating stuff

[@n3rdg4m3r]

No kidding! I knew about the o rings but not the interlocking sections with the pin. The things Scott Manley teaches never ceases.

[@tahini1]

welcome to scott manley's channel

[@djkamilo66]

thats why hes scott manley

[@Prophes0r]

"Dumbed down" is really a matter of perspective. You just happen to be in the target audience for Scott's content. It might be too advanced for some. Or too simplistic for others.

[@LoanwordEggcorn]

This IS a documentary.

[@RepRapper]

From someone who lives in Utah with 40 years of experience building rockets including the shuttle boosters. I don't know how you got your footage but it's the most accurate and informative video I've ever seen on this subject.

[@unistrut]

When I was at Space Camp back in the day one of us asked what would happen if the explosive bolts didn't fire. "They get torn off and the SRB leaves anyway."

[@TheOneWhoMightBe]

That's pretty metal.

[@WanJae42]

This is what I was told, too.

[@michaelbuckers]

Yeah they're designed that way. I mean it would be pretty stupid if the rocket exploded at the launchpad just because the hold-down device failed to unlock.

[@franzfanz]

@@TheOneWhoMightBe They'd be pretty ugly metal after that.

[@maxk4324]

@@michaelbuckers To be fair, its a problem pretty unique to solids. With liquids you want the hold down device to win out because you actually have the capability to shut them down rather than let them fly away uncontrolled in the event of catastrophic failure of some sort. But ya with solids your given the choice of finishing the burn here or finishing the burn elsewhere so the hold down devices don't really serve the same function. You likely already knew or guessed all this I just thought it was interesting info to point out.

[@mattattwell2954]

One of my favs Scott. I knew the general “leaking seal” conclusion for the mission disaster but you’ve just added a vast amount of fascinating info with a presentation skill that assumed reasonable intelligence. Thank you very much and please carry on.

[@bobroberts2371]

The shuttle program could have turned out differently had the boosters been built in Florida. Have a look for " Aerojet Dade "

[@silasmarner7586]

I didn't know until now that the initial oscillations stopped, and then windshear re-opened the gap. That's new data to me. Thanks Scott, and "Fly SafeLY"!

[@hoghogwild]

@@silasmarner7586 That is a sad fact. It's possible that if it werent for the windshear, that "slug" may have stayed in place.

[@byoung1520]

@@hoghogwild if Challenger had survived, NASA's appetite for risk would have increased, and another shuttle would have exploded later

[@DrewNorthup]

@@byoung1520 The launch timing of the Challenger craft, as those of us watching from our classrooms at the time know, was driven largely by an artificial political deadline imposed by Reagan's staff insisting on knowing when things were going to happen so they could structure the President's schedule. In reality Reagan was willing to be far more flexible than his staff pushed NASA management to believe and the shit-show of miscommunication and problem over-minimization snowballed from there. To claim that it was purely about risk culture just isn't accurate-humans fuck up in much more intricate ways than that on average.

[@TheSpatulaCity]

After 30+ years of knowing common knowledge about the Challenger disaster, this video really helped me understand the problem back then. Thank you.

[@Ron4885]

Me too. Never really gave much thought to the booster construction or how it performed. That was my bad. I didn't even know the nozzle could gimbal.

[@guintube]

Another part of each booster's propellant was about 18,500 pounds of Dow Chemical's DER 331 epoxy resin. It was used as a binder.

[@TheExplosiveGuy]

Is that on top of the PBAN binder? What is it's purpose? Is it a curative agent or something?

[@Formula1st]

I really want to know how you knew that

[@timg.413]

PBAN itself doesn't cure for a very long time and needs help. PBAN requires "other stuff" in order to cure and 331 is/was a common addative to assist in the curing process. There's obviously more to the process but this is what's behind the usage of 331 from my understanding.

[@-danR]

@@timg.413 Throwing more sh!t into the witches brew and see what sticks.

[@The_Seeker]

There is a hobbyist named Richard Nakka who has made his own mixtures and has a fantastic website, and the resin increases performance in addition to acting as a binder.

[@Xatzimi]

This is one of your best videos yet. I like it when you just talk about something you know, but 100% footage/diagrams really helps with the explanations, and a lot of the videos you used were just gorgeous to look at too

[@armr6937]

First time I saw one of these babies thrust vectoring was in one of Scott's vids. Dude has footage I've never seen anywhere else.

[@Henchman1977]

I was today years old when I learned the SRBs are lit from the top.

[@jcskyknight2222]

Well don’t worry, not all SRBs do it that way :D

[@andrewfarrow4699]

I thought it was a couple of blokes under the pad with a box of matches.

[@ronaldtartaglia4459]

Ian Colquhoun so you are two days older than me.

[@R3bel02]

@@andrewfarrow4699 Yeah, they pick the fastest ones.

[@ellenbryn]

Fantastic breakdown of the boosters. My dad worked for Thiokol, but I was a little young for him to explain them in this much detail when the boosters were first designed (I would've been about four or five), and after Challenger it was a little painful for me to quiz him about the specifics, especially with my classmates tormenting me about it. He worked at the small plant in Elkton Maryland that made the little kick motors like the separation boosters, probably the ignition booster and firing latches for the bolts at the bottom. I only realized recently that my whingeing about not wanting to move to Utah, which caused him to turn down a promotion, turns out to have saved him from being caught up in the O-ring debacle a few years later. When I was little they were doing a lot of interesting experiments in the physical properties of the rubber matrix of the propellant at his lab. He had bread mixers to mix little bitty test motors, scale models of satellite motors! I loved all the interesting forms they used trying to figure out the best interior shapes to achieve different rates of burn. They settled on star shapes with those long vanes, but it took them a while to refine that core. And there was a really messy few years in the satellite industry when Thiokol's original set of outer casings were used up and they went to a secons set and suddenly the propellant started peeling away from the interiors because the adhesive was just ever so slightly different! Gaps go boom. Gave my dad a lot of headaches back in the day. It was so early that they were using slide rules, so I know they couldn't have been doing computer modeling yet. Early shuttle design was a very hands-on, physical sort of ship design with a lot of scale model experimentation, since it couldn't be computer modeled yet. Somewhere in my parents house is a toy box with my childhood blocks made of honest to gosh rocket propellant. There was a "safe" version which was missing the oxidizer… It was just the rubber matrix, dyed green to show it wasn't explosive, used for tensile strength and other physical stress tests. Lab always ended up with all these oddly-shaped scraps that the scientists took home to their kids. I look for those blocks every time I visit my parents, but they're buried somewhere. They were great; they bounced! I'm sure that wouldn't be allowed now.

[@Tod_oMal]

Thanks for telling. Even if your dad was not directly involved, what were your dad's thoughts at that time about Thiokol and specifically the accident? If it's not too personal to tell. I was also very young but I can remember Thiokol took most of the blame, if I remember well. I can imagine it must have been very tough times for the family.

[@jamskinner]

Some of the inspectors told me they took the blame in return for being able to continue having a contract. Don’t know if that is true or not.

[@K3Flyguy]

Thank you for sharing your story, it was very interesting!

[@jaredhenderson6163]

My father started working for Thiokol on the shuttle booster program back in the 80's, and now I work for Northrop Grumman on GEM 63, so it's nice to see SRB's get some love. Thanks for another great video!

[@JonathanMensah-h3n]

Good on you, excellent. Crippen says they're going up to the spec'd 24mn. Swell, we'll be going places faster with bigger-heavier payload. We also AS-V1X for 'Juno', and a flyback tank that lands like STS.

[@isaid3311]

Wow thank you for answering the o-ring fix for challenger. The netflix doco only states the issue was the o-ring but didn't mention how they fixed it.

[@Astrocat-od5cy]

I gotta be honest this whole time I just thought that they fixed the O Ring issue by launching in the correct conditions

[@alexandrugheorghe5610]

@@Astrocat-od5cy me too. 🤦🏻‍♂️ Glad they took it seriously. I guess next time they should also listen more to their internal reporting when something is red flagged.

[@NarutokunJB]

I highly recommend Allan McDonald's book Truth, Lies, and O-Rings, available on Amazon. He was the key Thiokol witness who managed to alert the Roger's commission to blow NASA's attempts to cover up the cause of the disaster.

[@illuminati.official]

To be fair, while the immediate cause of the disaster was the o-ring not flexing adequately in the cold, the o-rings were never actually intended to do that job in the original design. If anything, the o-rings went above and beyond the call of duty again and again until they were finally pushed over the edge. The real underlying cause was that Thiokol and NASA decided not to redesign the boosters after they realized the original design was fundamentally flawed because it would've made for bad PR for the Shuttle program.

[@haroldpearson6025]

@@illuminati.official I understood the launch went ahead against the advice of the booster engineers due to political pressure?

[@crafty_crumbs]

One time my friends and I were making solid rocket fuel in the backyard using a coffee grinder.. the sparks in the grinder ignited the fuel quite explosively!

[@CarlosAM1]

Similar thing happened to me, was casting R-candy and it suddenly ignited and burnt my hand, arm and legs. 2nd degree burns everywhere, since then I have been too scared about it and have only made non-cooked R-candy, its a loss in ISP but I do not want to feel that much pain ever again. Edit: to which may I add I do measure the weight of the grains when dry packing to keep the engine results consistent, do it blindly and one engine might work and the next is a bomb

[@downstream0114]

You two going for a Darwin award or something?

[@crafty_crumbs]

Carlos_A_M so cooking it makes it molecularly bond better?

[@len.whistler]

I made Saltpeter and Icing-Sugar rockets back in the 1980's.

[@CarlosAM1]

@@crafty_crumbs Cooking it increases the burn rate and hence gives you more thrust in a shorter period of time, it also increases ISP, the propellants mix very well and unlike blind dry packing its way more consistent

[@CH-zw7ti]

I truly appreciate the beauty of the engineering films from this era!

[@RCAvhstape]

The footage from the cameras mounted on the SRBs during launch, separation, and splashdown is some of the most epic spaceflight footage ever made. Even has sound with it, so you can hear the wind whistling and the structure howl and creak as it tumbles downward. When the camera turns so you can see the orbiter and external tank screaming away at full thrust into the dark sky, that is just freaking awesome.

[@flashgordon3715]

"Era"!. I did work on shuttle stuff before it ever flew. Era, youngsters these day's, meh. 🤙 When Challenger didn't come back, I was so afraid it was something I might have missed. But I was way down the totem pole, like underground. Turns out the parts I tested were never intended for flight and are in a warehouse somewhere.

[@adamkendall997]

Footage from inside the fuel tank of a Saturn rocket is some of the coolest in my opinion.

[@andyheater]

does anyone kkow where we can find these slow motion films online?

[@RCAvhstape]

@@andyheater They're all over KZbin, and the ones that belong to NASA are public domain so you should be able to download them if you search NASA's website or maybe even write to them.

[@spaceflightbricks]

Great video as always! One correction though: at 13:58 you state that the extra segment means a longer burn time. I thought this was the case until recently too, however, the extra segment only adds extra thrust. The burn time is more of a function of the radius of the booster (propellant burns from centre outwards). It turns out the 5 segment SLS boosters burn for 1 second less than the 4 segment shuttle SRBs!

[@gelatinous6915]

That would (probably) entirely depend on the diameter setup of the booster. They probably opted for a larger "tunnel" in the lower segments for the new boosters, allowing them to burn faster for more thrust. Narrower diameters would add more fuel and more burn time.

[@michaelzilkowsky2936]

Fun Fact: The boosters acted totally differently than they had been designed to work, or to be more accurate, than the engineers anticipated. Engineers envisioned a uniform outward expansion of the booster case at the moment of ignition, which would have pressed the tang and clevis together and squeezed the O Rings. However, when they conducted the first pressure test of the booster, they were astonished / surprised / shocked / confounded / flabbergasted to discover that the casing ballooned outward above and below the field joints, aka joint rotation. Instead of the joint sealing tighter as they assumed, it opened up (this is a separate phenomenon from the 3 to 4 flexes per second that released the built up pressure of The Twang). Joint rotation was an even more serious threat to the shuttle program than the resultant O Ring erosion (which was waived as an acceptable risk) because a complete joint redesign would have not only been expensive, it would have required grounding the shuttles until the joint was fixed properly.

[@thomasjamison2050]

My father developed guidance systems for satellites and warheads. He always complained that most everybody just couldn't seem to properly comprehend the magnitude of the pressures held in the system. This all is getting to be something from a long time ago...

[@adrianfewster8391]

There never should of been sections. NASA should have paid the extra for a one peice srb, saving 7 lives. $ priority over safety costs lives.

[@michaelzilkowsky2936]

@@adrianfewster8391 I think a one piece casing would have been wildly impractical because of the transportational logistics as well as the fact NASA spread its contractors around the country (especially to States with representatives who voted money for NASA). Once the joint rotation phenomenon was known, they could have added the capture piece to the inside of the top joint, or simply have listened to the engineers who begged and pleaded not to launch below 53 degrees.

[@adrianfewster8391]

@@michaelzilkowsky2936 One piece srb designs were offerred, and with ocean transport supply, however rejected in favour of the Thiokol cheaper offer with compromised safety using o-ring sealed segments for road transport, What are 7 astronaut lives as well as the loss of the complete shuttle worth in comparison to srb savings ?

[@JoeBlow-bd1eg]

@@adrianfewster8391 or maybe just don't launch when there's ice on the launch pad.

[@jfischer507]

"backbone of the shuttle" more like the glutes and quads

[@chuckkimber2773]

LOL! Never skip booster day at the gym!

[@maxg4304]

The shuttle doesn't skip leg day.

[@SukacitaYeremia]

All three at once I dare say...

[@oldcarnocar]

except 4 the crappy o-rings

[@moosemaimer]

How do you go to space? *SQUATS*

[@rorypenstock1763]

Finally, I get to learn about the space shuttle booster TVC! I've been wondering about it for a long time.

[@221b-l3t]

Yeah me too. I always wondered how they could move considering they needed a flexible part that could take the immense heat. But lots of metal plates it is :)

[@deadhamster7570]

@@221b-l3t The rubber seal is the most impressive thing imo. What did they tell the material scientists? Umm, we need a flexible material that can handle a thousand degrees and 60 bar...

[@zoperxplex]

More than twice as powerful as the most powerful liquid fuel rocket engines.

[@alponselrik]

yes.... but it would make bad ISP i guess that's why we rarely see a solid rocket at the upper stage

[@MrDJAK777]

@@alponselrik Probably less to do with isp (while important its benefits could otherwise be outweighed by some of SRB's other benefits) and more to do with second stages often needing to shutoff, coast, have variable throttles, and the ability to* reignite multiple times to make adjustments or get into the proper orbit/position for deployment of satellites.

[@MCWaffles2003-1]

@@MrDJAK777 adding SRBs to upper stages is so innefficient it actually reduces the total dV of a rocket typically

[@emilybraswell4570]

​@@MCWaffles2003-1 Then what about the STAR family of solids? They are almost exclusively used as kick/third stages.

[@Bizzon666]

@@MrDJAK777 Both are the concern on upper stage, control/restartability and Isp. But some launchers still use solid upper stages or apogee kick motors, I guess because of the simplicity and price. Lot of satellites don't need to get into exact orbit by the launcher, most geo-stationary satellites do the last circularization burn maneuver using their own propulsion. There are just too many parameters and different approaches, and very few universal solutions.

[@wacojones8062]

Good Report. Back in 1971 I was at Indianhead Maryland Naval Ordnance station when a disposal burn of a cracked Polaris motor detonated 1/4 of the way through the burn. Shockwaves from the blast carried by the limestone bedding layer cracked the Capitol basement wall. Both the test fixture and the Capital rest of the same rock layer. 3,000 pounds of propellant went bang in a split second.

[@garfield4108]

That was really interesting. I always wondered how the shuttle joint was improved after Challenger. It makes the original look high risk after all the fail-safes added in the redesign.

[@MoonWeasel23]

Never knew that about the wind shear on challenger’s last flight.

[@TheJoeSwanon]

Especially considering you hear rocket launchers getting delayed all the time for windshear They really were in a rush to get that shuttle launch

[@patricks_music]

@@TheJoeSwanon That's really too bad :(

[@dpreston8831]

jonathan lavezzi what’s worse is multiple engineers even told them that it would fail the night before. The document didn’t become known until a few years after because they tried hiding it.

[@dankuchar6821]

@@TheJoeSwanon Yep the engineers from Morton Thai called told them they hadn't tested the o-ring seals for temperatures that low and they didn't think that they should launch. NASA did it anyway. Stupid mistake. NASA had way too much bureaucracy. Apparently they still do. That's one of the problems with government run programs. There's very little incentive to be efficient and eliminate unneeded bureaucracy.

[@toreyweaver9708]

Neither did I!

[@Galactis1]

Than you Scott, this is actually a very, very well done video. I researched the crap out of this and am so happy you put together what I thought of. :)

[@LoanwordEggcorn]

Scott does a great job of both synthesizing and presenting material.

[@-danR]

However, he will never top his classic assessment: "you strap on solid boosters and pretend it's a rocket."

[@mikemcgill4140]

When I was a kid in the 70s we moved to Utah because my dad was a supplier for the Solid Rocket Motors being built by Thiokol. We made some great memories with a lot families whose parents worked on the program.

[@Tod_oMal]

Must have been painful days for everyone of you and the other families, even if your dad was not directly involved with the cause of the accident. I was very young but I remember Thiokol took most of the blame.

[@devgru8197]

As a military veteran, aerospace and aircraft enthusiast, and electrical engineer, I absolutely love your videos. Very very informative and detailed. Strait to the point. As a child growing up in the 1980’s, I would’ve loved to have these videos then. I was always fascinated with NASA, the military, and more specifically, the space shuttle. Keep up the good work!

[@wolfiefink]

That’s some Solid engineering there

[@digitalman01010]

Awesome video! One thing you may be interested in looking was the precursor work done by Thiokol, who developed the SRBs as you mentioned. Their experience with solid fuel came from their earlier work for the Air Force on the Minuteman ICBM program. Back in the 60s, if you wanted to launch an ICBM, you had one of two options: You could use cryogenic propellants, but these meant the the rocket had to be fueled before use. This meant the rocket force was at risk of being taken out on the ground before they were fully fueled, and once fueled, they had to be used within a period of time before too much propellant boiled off. The alternative was hypergolics, which, while storable, were incredably toxic as you've covered before. This was undesirable in a silo, and a non-starter on say, a submarine. A solid fuel ICBM on the other hand, was safe to store for long periods and didn't need to be fueled. It was groundbreaking in the 60s, and gave them the experience needed to adapt it to the SRB.

[@softb]

ah just when I was about to go to sleep, thanks scottt sleep safe

[@richy77]

lol same right

[@alantownsend5468]

Same!

[@richardmillhousenixon]

Who needs sleep amirite??? ᶦ ⁿᵉᵉᵈ ˢˡᵉᵉᵖ ˢᵒᵐᵉᵒⁿᵉ ᵖˡᵉᵃˢᵉ ʰᵉˡᵖ

[@ryannovakovic5046]

Sameee

[@rancidbeef582]

Thing I learned today thanks to this video: that Richard Feynman was on the Challenger accident commission. Of course, didn't know who he was back then...

[@bimblinghill]

There's a good TV movie called 'the challenger' which goes into his involvement in this (not to be confused with a similarly named crap movie)

[@EthelredHardrede-nz8yv]

I was able to see that on NASA TV because my cable carrier had it. Its odd the way I found out about Feynman. My brother came home from an art class and his teacher had told the class about a PBS show that about him so we watched it. Because of an art class. This was before the Challenger disaster. I found about the disaster because my brother's girlfriend called up to tell him that something had gone wrong with it. She worked at JPL.

[@robertreynolds1044]

I can't find that PBS special on Feynman, but I have spoken with Steve Miller about him in relation to Tuva and Paul Pena,watch Ghengis Blues and you will learn even more about everything. I'm Bicycle Bob and I approved this message.

[@illuminati.official]

You should read Feynman's account of the Commission in _What Do You Care What Other People Think?_ He really goes into it.

[@robertreynolds1044]

Richard Feynman, the real "most interesting man in the world"!

[@Greg41982]

I grew up in Utah and always had a special place in my heart for the SRB. The Challenger Disaster (happened when I was in elementary school) soured that a bit, but I was always proud that my state was a part of such a cool program. Thanks for the great video!

[@diGritz1]

Guy In Charge: This is your first day working so we'll make it easy on ya. Just gonna have you crawl in here and pull that pin. Newbie: Pull a pin? The one with the big red tag that says danger don't pull this pin? GIC: Yep, no worries. You did kiss your wife and tell your kids you loved them this morning right? On a side note, I remember Feynman's ice water demonstration. They were not happy about that.

[@GenoLoma]

Being the 80's I hope he took off his polyester jacket first.. that static be a bitch! ;)

[@chuckkimber2773]

This may be the only channel to ever give SRB's some love. I've heard Thiokol invented the modern car airbag based partly on the booster ignitor. SRB's have been saving millions of lives ever since! ;)

[@-danR]

Scott's channel however has also thrown the most immortal shade at SRB's for all time: "You strap on a couple of solid boosters and call it a rocket." I'll never forget that quip for the rest of my life.

[@chuckkimber2773]

@@-danR I remember it. While he was trash talking OmegA. I suspect he caught some flack for that and it's the very reason this video now exists. LOL!

[@headcrab4090]

@@chuckkimber2773 I wondered about that too. I felt he trash talked the Vega-C as well then. Now I am happy again.

[@youtubevanced4900]

Why do we bother abbreviating MAX Q? I've literally never heard anyone say it without following it with an explanation of maximum dynamic pressure.

[@dpreston8831]

Acronyms!!! The world of military/government is filled with them because it takes less time to say it so the comms can stay open

[@notapplicable7292]

Literally, every rocket launch has a callout for MAX Q without an explanation. We just have the presenters filling time by explaining MAX Q, mission control doesn't hear that.

[@MuscleMarker]

Q is the symbol used for dynamic pressure in fluid dynamics calculations.

[@ElectroNeutrino]

The same reason why we use the phrase "delta V" when talking about how much fuel is in a spacecraft. It's a common variable used in the equations.

[@jwilder47]

Because it's a way better name for a band then Maximum Dynamic Pressure.

[@seancoate5695]

I am a shuttle GEEK, but I never knew what the splash was pre-splash of the booster. Thank you!

[@dontgetmadgetwise4271]

Mind boggling to appreciate that every tiny component had design and manufacturing teams. Complex engineering is a wonderful thing.

[@Oddman1980]

12:45 It never fails to scare the hell out of me when intelligent, and educated men and women solve a problem with a complex piece of machinery by doing something I would have tried. There's a lot in this video I didn't know - first, I'd always assumed the casings were aluminum, because of the whole "big flying thing", and second, I thought the star-shape went the entire length of the booster, instead of the first stage. Another excellent video!

[@Mozartenhimer]

Thank you for not premiering this!

[@noxabellus]

Who cares?

[@yacinesenouci6680]

He premiered those 2 because the sponsor told him to

[@redroyal4287]

What's the problem with a premiere?

[@arro_rockets]

What I find interesting is that many composite commercial model rocket motors use the same APCP propellant as the Space Shuttle SRBs

[@ElTurbinado]

It's a very efficient fuel plus we have the production facilities for it in place already (well, the facilities that didn't explode and turn into classic disaster videos, anyways...).

[@fiftystate1388]

11:44 "another factor," upper atmosphere winds. Thanks Scott, new to me. 3:07 cc: reads "very high quality high strength miraging steel" (sic) *Maraging steel* en.wikipedia.org/wiki/Maraging_steel

[@vladimirarnost8020]

Thanks for the link! The day I learn something new is a good day.

[@PSYK0MANT1S]

This is the type of engineering content I subscribe to. Simple explanation, no fat, no fluff.

[@mche7214]

we are still learning about the boosters,the loss of thrust calculation to fuel ratio,the timeline and the base loads.glad to explain .

[@Kylefassbinderful]

You really deserve some sort of award for this video. You don't over complicate or over simplify anything. I'm not an expert or anything close to that yet I was able to understand everything you said. Needless to say i'll be subscribing after I leave this comment.

[@gideonmiles7161]

6:00 "remove pin before flight?"

[@TheJoeSwanon]

That’s a brave man

[@rileyk99]

The pin locks out the electromechanical "Safe and Arm Device" so basically the guy pulls the little pin out of the bigger pin :P

[@DRpotatoYT]

@@rileyk99 the "SAD"

[@cursedcliff7562]

@@rileyk99 Pinsepcion!

[@johndododoe1411]

Like the pin on a grenade. Countdown doesn't start until you release the big lever by throwing it.

[@CreativeEm]

Amazing explanation, as always, Scott, though I'm sure I'm not alone in being instantly nauseated seeing the disaster again. May they, and indeed all those lost in the quest for space, never be forgotten

[@veramae4098]

Christian Science Monitor (newspaper) had editorial cartoons by Danziger. After the explosion he did one for Christa McAuliffe -- a desk, flag hanging, her name on the chalkboard, some of the great books like "The Right Stuff" on her desk. I cut it out and had it framed. Still have it.

[@wholenutsanddonuts5741]

SRBs are crazy beasts!! :)

[@michaeldeierhoi4096]

Good update on the SRB's. You have demonstrated the sophisticated technology that went to these boosters and they do seem to be still a very useful tool in enhancing booster lift capability.

[@CuriousMarc]

So much great information I had never seen before. Had to watch it twice to get it all!

[@matt8863]

9:54 I was hoping to not hear those dreadful words that defined absolute "incompetence" on so many levels in 1986 and beyond.

[@ArnoldClarke]

What happened in 1986?

[@ArnoldClarke]

The one that blew up matt8863?

[@RepRapper]

First of all. The engineers at Thikol tried to stop the Challenger launch. The Bureaucrats didn't listen.

[@Octa9on]

The SRBs were a terrible idea, but at the same time absolutely amazing.

[@jshepard152]

Exactly how I feel about the shuttle program.

[@P8nda]

*I have never been so offended by something I one hundred percent agree with.*

[@woodduck2178]

But they still look amazing

[@Y.M...]

But why were they a terrible idea?

[@Galactis1]

No, SRB's are amazing! seriously cheap, seriously efficient and powerful

[@LarryB-inFL]

A rather odd factoid: According to an old BBC show called "Connections", the size of the solid boosters was limited by the width of the railway cars and tunnels from the Utah facility, and those in turn were based on the track widths, which in turn were based on the width of common horse drawn carriages of the day when railroads started, which in turn were based on the ruts in the dirt roads that criss-crossed Europe, which dated back to the days of Roman chariots, which were designed based on the average width of two horses running side by side. So the SRBs owe their design width to the width of two horses asses!!!

[@jwadaow]

Which were based on the Indo-European chariots designed on the Pontic steppe.

[@nobodynemoq]

... which was not true, however a nice hoax :)

[@divedevil985]

The United States used a different railroad gauge than Europe. Rumor has it that railroads in the US were actually reverse engineered by time travelling shuttle astronauts who knew they would need to be large enough for future SRB transport.

[@jwadaow]

@@divedevil985 there isn't a European gauge. Different countries use different gauges. As exemplified by the logistical challenges Germany faced moving eastwards in the early forties. Even different countries used multiple gauges. In the country where trains were invented the lines were made by competition between private firms and there were competing gauges.

@@jwadaow Not true, but whatever :)

[@8squarefeet190]

Great explanation Scott! I was always stunned at how much the shuttle stack moved when they lit the mains, the whole stack would flex over, and then the boosters had to wait for the whole assembly to flex back.... and that shot of the shuttle at 13:45, showing how the whole assembly slides off to one side as it comes off the pad.... The thing that always amazed me was how fast the shuttle left the pad. As a very young person (5 at the time), I clearly remember laying on the floor watching TV of Apollo 16 and 17..... and they took FOREVER to clear the pad. Comparing the two spacecraft now.... the Saturn's were 18 wheelers leaving a stop light.... the shuttles were corvettes launching on a drag strip. Thanks for the video! Hope the smoke is clearing up on your side of the Sierras!

[@jbidd8647]

Believe it or not, that rocking motion was called "twang."

[@Ferro_Giconi]

I'm really glad you covered the oring and how they fixed it in so much detail. All these years all I ever heard was the extreme vague statement "an oring failed" which tells me no more about what actually happened than saying "it went boom!"

[@SpaceStickwithSpaceTick]

idk man seems kinda easy to build multi-ton boosters for rocket science.

[@mechanicalrocketeer4900]

Not that easy trust me❤️❤️❤️

[@maxnaz47]

@@mechanicalrocketeer4900

[@psyko2666]

"I mean, it's just some clay and a tube. How hard can it be?"

[@BloodSprite-tan]

@@psyko2666 well if you wanna find out just go the elementmaker's channel and you can watch them build tiny little rocket engine, that fail horrible, because clay is not simple in the least bit.

[@vincentcleaver1925]

@@BloodSprite-tan fantastic channel; I have almost no interest in actually doing it myself because I know better and he's very clear on why you don't simply play with high energy chemicals what get very pissed off...

[@mjproebstle]

hello. another awesome vid, you just boosted my day...thx!

[@CarlosAM1]

Heh, see what you did there.

[@mjproebstle]

Carlos_A_M 😉

[@P8nda]

*komedy*

[@banthaboss6390]

Hey Scott, what was the documentary footage of the srb's from? I would love to watch it! Another amazing vid as always. Fly safe.

[@TheMonthlyJack]

I think iv seen them in discovery channel documentary. Ah, it was Extreme Machines: Rockets

[@banthaboss6390]

@@TheMonthlyJack perfect. Thanks!

[@catfish552]

Search for "Best of the Best NASA" here on KZbin. It's a 45-minute video on NASA's channel that's all slow-mo footage of shuttle launches with commentary from NASA engineers. Great stuff.

[@banthaboss6390]

Just when i think I have watched every shuttle and nasa doc, i find out there are even more. Guess i will have to watch all of them!

[@geoffreydowen5793]

sutch a horrible event explained quite proffesionally I'm a luddite but find your posts really informative, like I'm having a personal science lesson. I'm 64 stroke survivor and find these lessons on space exploration and technology so wonderful.cheers Scott, from the sofa in Suffolk England.

[@thelorax9622]

That shuttle video is one of my favourites - the clarity of the slo-mo video is outstanding. Good choice.

[@Heisenberg618]

"Somebody has to go into the nose of the booster to pull the pin." - Wonder if they drew straws.

[@ADTR513]

Just finished the Netflix series, Scott! Excited to see what you have to say!

[@djkamilo66]

whats the name of the series?

[@dougpowers]

@@djkamilo66 Challenger: The Final Flight It's an excellent series which balances the science and politics behind the development of the Shuttle with some heartbreakingly detailed profiles of the seven astronauts who lost their lives due to NASA's cultural mismanagement.

[@rayramos6970]

Same I saw it too

[@djkamilo66]

@@dougpowers thank you

[@stefanfritzsche]

same here - the timing of this video is perfect. just watched the series on Netflix and was wondering HOW exactly they fixed the O-Ring problem in the end. that part was fascinating. to see actually how complex the solution was; explains why it took them two years to develop and implement it. also, as @dougpowers said, the series paints a very detailed picture from a balanced perspective. I can really recommend it.

[@jankorenberg9773]

You just clicked on a Scott Manley video..now be prepared to learn something new.

[@erikincph]

A lot better and informative than you find in any tv channel.. We are lucky that Mr Manley haven’t been contracted for other tasks and deeds...

[@scottdorfler2551]

You have an amazing way of presenting complex material. I never get bored watching your channel. 16 minutes of jam packed learning. Thankyou!

[@Xenro66]

6:00 So the takeaway from all this is that SRBs are overgrown grenades. Gotcha

[@d.jensen5153]

@Xenro66 APCP does not detonate. That difference cannot be overstated.

[@gong1616]

They are the forefather of the strap-on dildo.

[@BSJinx]

Once you have ignited Mr. SRB, he is no longer your friend.

[@divedevil985]

tell me when a solid rocket booster casing was shattered by the internal pressure?

[@divedevil985]

@@aemrt5745 I worked in every phase of srb from recovery to refurbishing. Please dont reply to me as if you have a practical clue about anything regarding a solid rocket motor because you dont. No booster casing used on the shuttle program ever remotely came close to an over pressure.

[@charanaa3023]

So if the assembled booster is hit by a lightning strike on the pad, when the safety pin has been removed, there is a non-zero chance the booster could light taking everyone on a one way journey?

[@jwilder47]

That's why the launch tower had that big spire on top, it was supposed to direct any lightning away from the shuttle stack.

[@Shadow77999]

@@jwilder47 lol

[@ctleans6326]

@@jwilder47 If that's true, that means they really, really, thought this out.

[@Xatzimi]

@@ctleans6326 It's NASA, of course it is. But it's correct that that big thing on the tower is a lighting rod

[@rileyk99]

I mean, it must have worked because the stack was never hit by lightning.

[@InventorZahran]

6:16 *Seperatrons

[@rattywoof5259]

Eh? 'Separation' is the correct spelling.

[@artysanmobile]

Fantastically complex. This is a standout video, Scott, with exceptional graphics and footage. My favorite of yours. Thanks!

[@edwardhewer8530]

Geez this video is outstanding. Thanks heaps. Had no idea the nozzles were gimballed. Didn’t know about the wind shear Challenger experienced either. I thought these boosters were a lot more simple. Rocket science indeed.

[@JonathanAdami]

"let's talk about the joints" I agree, let's!

[@thethirdman225]

Sounds like a Cheech & Chong sketch...

[@JonathanAdami]

@@thethirdman225 had to google that hahaha I guess I know what I'll be doing from now on! :D

[@thethirdman225]

@@JonathanAdami Have fun!

[@dr.OgataSerizawa]

Jonathan Adami Got me through high school from 66-70 !

[@lalafellgaming]

Learning about shuttle era technology makes my rocket motor solid

[@InventorZahran]

Well my liquid rocket booster gains rigidity when its tanks are pressurized...

[@lalafellgaming]

@@InventorZahran your comment made me experience max-Q

[@ethanprober5417]

I wonder what kind of redundancies they built into the explosive bolts that held down the boosters (1:30). Once you light the boosters they're firing for the full duration, and it no bueno if one bolt didn't go off.

[@tomb504dog]

Ethan Prober I believe that on at least one occasion one of the nuts didn’t separate. The shuttle took off like it was nothing; breaking the metal plate.

[@noodlesthe1st]

My guess is if one bolt didnt go off it would be ripped out. SO the redundancy is that more than one bolt would have to fail. Possibly more that 2 or 3 even.

[@captainoblivious_yt]

It definitely has enough strength to rip off one faulty bolt.

[@edwardgiugliano4925]

It's nice to see solid propellant motor technology finally getting some love! Thanks for this.

[@Tinman97301]

They need to back log this video in every documentary ever made about Challenger. Because to me "an O-ring got cold and failed " never made sense. Hell, That's not even the half of it. Best explanation ever! Thank you.

[@jasonmurphy9647]

Damn that safety pin means the move Space Camp couldn’t have happened.

[@paulgordon9648]

Worked as a Minuteman III ICBM mechanic in the 70's . Was always glad to work around the solid propellent systems . Seems to be much safer than the liquid fuels .

[@texasyojimbo]

So you're saying these are *slightly* more complicated than the good old Estes B6-4 engine?

[@don312000]

Just a bit! Same principle, though!!

[@divedevil985]

I don't remember my B6-4 having a hydraulic system and actuator to gimbal the nozzle, not to mention a hydrazine APU and avionics among other things.

[@lorenwilson8128]

One of my professors consulted with Morton Thiokol and talked about the boosters used on the space shuttle. The previous longest-burning solid-fuel boosters burned for one minute and it was thought by most engineers that this was the limit. The longer burn time wears out the exhaust nozzle. The exhaust is essentially molten sand mixed with gasses, coming out at mach 8, and is very abrasive. The shuttle booster was an engineering challenge.

[@Rincypoopoo]

I had forgotten the wind shear. Great video again. Keep them coming. And proper Scott Manley music too ! Thanks.

[@zapfanzapfan]

2:28 Temperature limits 40-120 F... someone ignored that...

[@RideAcrossTheRiver]

The _Challenger_ accident was a convergence of factors: cold, the SRB design, and unexpected wind shear aloft.

[@jmannUSMC]

One of my engineering goals is to one day work on these big dumb pieces of awesomeness

[@maxk4324]

Go for it!

[@stevec5586]

4:16 "the thickness (of the propellant) will control the burnt rate" No it doesn't. Thickness has minimal effect on burn rate. In solid fuel rocket motors that burn continuously from start up, the burn rate is determined by the surface area of the internal propellant surface. Subtle shaping of this surface, including non-cylindrical and variable profiles, is used to achieve the desired burn rate and burn profile during the flight. My ex-wife was a rocket scientist!

[@John.0z]

I read a bit about the boosters when they were the latest technology - and a fair few of the details mentioned here were not noted. Thank you yet again Scott.

[@tensevo]

One of the best explanations of the Challenger O-ring failure and counter-measures.

[@chrisvance7824]

Just here pretending I know what he's talking about

[@rabidbigdog]

* mostly amazing when warm enough.

[@SinisterMD]

Allan McDonald. Say his name.

[@wythetrumpet6419]

As a note Thiokol was purchased by ATK Launch Systems, then Orbital purchased ATK, forming Orbital ATK, this was short lived when Northrup Grumman purchased Orbital ATK. As of September 2020 the SRBs are manufactured by Northrup Grumman. Great video!!!

[@Kawil12]

Really great video. Thanks for a more robust explanation of the O-Rings and of the boosters themselves. So much technical info you gave but in a way that was really easy to understand. Great job!

[@patricks_music]

"Will continue to do so for the SLS" Me: If we get it to fly :(

[@emilybraswell4570]

The core stage is the only thing holding it up, and the 6th of 8 tests on it takes place this week. It's almost here, at long last!

[@patricks_music]

EJ Braswell i’m super pumped for it. I would love to see it fly. It’s just a shame how much politics and sus money stuff has been going on too

[@playgroundchooser]

It literally just got pushed to 22, right? Just put SLS out of its misery.

[@emilybraswell4570]

@@playgroundchooser No? It's scheduled for July '21 but can be pushed back as late as November.

[@dalel3608]

" If we get it to fly :( " Ha, it'll fly, as will its 12 following cores.

[@frankzheng9403]

lol, just finished watching Challenger: The Final Flight on Netflix, and this came up.

[@scottmanley]

You do know that Netflix bases it’s recommendations on things you’ve watched right?

[@captainoblivious_yt]

@@scottmanley *Gets "Cuties" recommended* Uh-oh

[@Edax_Royeaux]

Just imagine putting 5 SRB into a cluster and you effectively have a Saturn V sized rocket again.

[@codymoe4986]

Five 4 segment SRBs like the type used on the shuttle would have around 13 or 14 million lbs of thrust? Almost twice that of the Saturn V if the numbers I read were correct...

[@Edax_Royeaux]

@@codymoe4986 Only against the first stage though. The Satern-V's S-II J-2 Engines had a 500 second burn time, something the SRB can't come close to achieving.

[@iraqgsmtech8895]

The most informative, and comprehensive video about solid propellant rockets on KZbin so far. Very good job 👌👍 thank you Scott!

[@88rednumbers]

Loved this video...after watching the challenger documentary on netflix, this video is stellar...

[@henryfeng5311]

The new netflix show “the challenger: the last flight” tells us that the O ring, which was a part of the solid rocket booster was the cause of the tragedy for the challenge. The O ring was used for sealing the components of the rocket booster, but they had a massive issue with low temperature. The elasticity were inversely proportional to the temperature and hence making it more fragile under extremely cold conditions.

[@ReverendTed]

7:22 - Figure 4: Illustration of proposed technique for management of bureaucrats

[@InventorZahran]

What? Blast them with the engine? That'll require some costly cleanup... (does a funeral count as "cleanup costs"?)

[@scorpio6587]

funny stuff

[@ВалентинКомаровский]

Musk does without solid fuel crutches and without magic hydrogen

[@thesunexpress]

@8:00 ffs for YEARS I'd been wondering WTF the thing that hits the water first was all about! Thank you!!

[@jimmyjames2022]

Awesome explanation of the solid fuel, the Challenger O-ring issue and the complex improvements that worked, plus great footage of the booster assembly and launches. In my mind the shuttle had launched military missions from Vandenburg so I am now straight that it hadn't.

[@jon6288]

One of your best videos in a while. Nice job.

[@aatheus]

Enjoyed your deep dive on this. Especially getting a chance to see a lot of archival footage that I have not seen before. Great stuff.

[@MrWATCHthisWAY]

Clear and concise explanation of SRB systems used by NASA. Fly safe!!

[@favesongslist]

Your videos are always so interesting and lots of information that is completely new to me; despite watching 4 space shuttle launches and loving the awesome force of the acoustic shock wave hit you. I cannot wait to see a full Starship launch.

[@-Kerstin]

Great explanation of the O-rings