Did False Circles Cause The Challenger Disaster?

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[@TheActionLab]

In this video I am showing how the tests that NASA did on the re-usable rocket boosters was not adequate to catch any boosters that were out of roundness. These were reusable rocket boosters that were taken apart and reassembled and then tested for roundness. If they were not round then this would only add to the problem of fuel leaking from the joints and non-conforming o-rings. NASA has now changed how they measure roundness. This doesn't mean that the rocket boosters were for sure out of roundness, but their test for it could not catch it. Richard Feynman himself proposed this theory while he was on the committee investigating the disaster. He describes it in his book "What Do You Care What Other People Think?"

[@bobbybologna3029]

Unfortunate that you have to hammer this out repeatedly, I thought it was pretty obvious that the lesson was about false circles and not the segue into the lesson about false circles lol.

[@JohnnyWednesday]

Are you 100% sure about this? yeah their tests were insufficient - but what about the manufacturing process? was that insufficient?

[@BackYardScience2000]

How do you know that this is how they measured the roundness of the boosters? Can you provide citation for the claim that this was the only way that they measured them? I find it kind of odd that they would only measure them in this way. It seems to me that they would have had issues like this before and would have found other ways to measure them, along side using this method as well. This theory just doesn't make sense to me, like, you'd think that they'd be more competent than that when measuring and identifying flaws. Please post citation for what makes you think this to be the case, or at least part of it. I'd love to see where it says that they only measured in this way and no other way and determined the boosters to be adequate for use in the shuttle and safe to use and not just an idea that isn't provable since we can't recover enough of the booster that failed to be able to take the measurements.

[@gothicbagheera]

If their tests were inadequate, and that inadequacy could have been a factor in this tragedy, then you need to explain how the booster sections not being perfectly cylindrically round could cause the o-ring to not seal the two sections together properly, when they were initially assembled. Plus, where did you get the idea that the booster sections might not have been perfectly round, and thus a factor that led to this disaster? I've never heard that as a guess, let alone an actual factor. My dad happens to be one of the people that was directly involved in the investigation, and when I asked him, he said that was never an initial thought nor a conclusion reached, at any point in the investigation.

[@MeatMachine69]

The Challenger crew didn't die instantly from the fireball, the cabin was still intact, likely most of them died from lack of oxygen

[@brandonn6099]

*For those wondering how false circles cause failure,* it's because two false circles are unlikely to align properly with each other. This will leave gaps between them. Gaps too large for a cold o-ring to fill (or as the pressure inside made them perfect circles the o-rings couldn't flex enough)*, or gaps that cause too much pressure on a weak joint. Had the cylinders been perfect, the imperfect o-rings may have worked properly, and the weak joints would have been under less internal stress. The effect of imperfect circles on aerodynamics, thrust, or internal explosive force would be negligible. They were mostly round, barely imperfect, and caused very tiny gaps. *Edit: thanks Joe, that's a good possibility

[@Bradley_Warren]

@@liefschneider3123 Any sphere has imperfections to some degree. We don't have the ability to make "perfect" spheres.

[@anthonyjohnstone695]

@@Bradley_Warren Yes we do that's why people are able to machine balls

[@afriendofafriend5766]

Your comment did a better job of explaining this topic than the video did.

[@JoeFrickinFriday]

@LessThenThree Assuming Thiokol actually did only measure the diameter of booster segments in one spot (as opposed to measuring runout), it doesn't prove that they were false circles; it just didn't prove that they weren't false circles.

[@JoeFrickinFriday]

The O-rings were likely sealing just fine before ignition, even if the booster shells weren't perfectly round. That is in fact the entire purpose of O-rings: to fill in gaps between two surfaces that don't mate perfectly enough to form a seal on their own. The problem was that the mating parts of the booster segments changed shape when subjected to the 1000-psi operating pressure after ignition, and ice-cold O-rings on launch day couldn't change shape quickly enough to maintain the seal when the booster segments distorted. The SRB field joints were redesigned after the Challenger disaster, but there's nothing in the descriptions of the new design that mention out-of-roundness or false-circle phenomena. As badly as NASA performed in the lead-up to the losses of Challenger and Columbia, I'd like to think that the forensic efforts trying to figure out what caused the failure would have known whether false circles were a problem.

[@paladin_pat]

Could you tell us more about how false circles would have caused the rocket to fail? Is it because it affected things such as how much resistance it met when trying to leaving the atmosphere?

[@nostalgic7752]

Same question here

[@fiusionmaster3241]

Agreed

[@Andreamom001]

Others are saying the pressure inside from the gas would be unequal in a non-circle, causing some spots to receive more pressure that might make a failure point.

[@Andreamom001]

But yeah, he often doesn’t explain things well in his videos, imo.

[@n2n8sda]

Most likely the rubber seals that were fitted between the sections of the tubes that made up the booster rockets to seal the joints (failure of these due to low temperature is the official recorded verdict). These seals were circular in shape, designed for a round tube, they could have been distorted due to the non round shape contributing to their failure in low temperatures.

[@stratagama]

I've been finding a lot of these videos that I watch on this channel incredibly frustrating because it'll introduce an incredibly interesting premise but it does not follow them to their conclusion. It doesn't explain how a false circle rocket booster would lead to explosion doesn't address if this was a serious concern that they were looking at an addition to the o-rings and the joints just a load of vagueness

[@tonywilson4713]

I haven't seen any of his other video's so can't comment. On this one see the answer by "Brandon N" I am an aerospace engineer and his answer is something that should have been in the video.

[@bobsondugnutt2519]

I'm finding myself having these same thoughts after watching this. Seems like half the video got lost in the editing

[@The_Essential_Review]

Exactly my thoughts

[@shorty808100]

A perfect circle is the strongest shape there is but if that circle isn’t perfect it has a weakness we’re the false circle part comes in which cause failure to occur because the pressures inside the SRB is too high for the false circle to handle hope this helps you understand better

[@MontanaRealtyCompany]

He used to make longer videos in the past. But has definitely shorten them up a lot. But going back to this particular video. He is basically bringing up a theory as to what could've caused the issue, but he can't really prove it. So the length of this video is enough to go straight to the point and explain what false circle are.

[@999fine5]

That didn't exactly explain why the Challenger would have exploded because of those shapes.... How does an odd shape like those cause a shuttle to blow up? Interesting info tho.

[@DystopiaWithoutNeons]

I think it's related to the ring capability to seal correctly.

[@p0pimp2004]

He gave 3 possible reasons. Werent u listening?

[@g45sp4]

You have been clickbaited ny friend

[@timscoviac]

@@p0pimp2004 he gave reasons at the start but didn’t really explain what the shapes had to do with it after showing us everything about them

[@calvinlee1127]

@@p0pimp2004

[@poofpoof9940]

You've been a very informative source for a long time, but if you'd answer the HOW x affects y, and why and not just what when and where it'd really take your videos to the highest tiers of science information.

[@fiusionmaster3241]

Yes

[@bobbybologna3029]

That's not the scope of the video though

[@modelt8951]

@@bobbybologna3029 the title is literally "did false circles cause the challenger disaster" it definitely should be within the scope to answer that question

[@poofpoof9940]

@@bobbybologna3029 its directly implied from the title and thumbnail, that the answer is presumably yes, and he will tell us why and how.

[@cloudricklloyd1]

It really sounded like he was onto something and then the video just ended .. lol

[@GrimJerr]

It would have been more informative if you went into how a noncircular shape affects the aerodynamic forces on the shuttle launch arrangement, and how that may have contributed to the disaster, but it was a nice primer on the subject

[@fiusionmaster3241]

@@ronaldwanders mabey

[@Blackmark52]

"how a noncircular shape affects the aerodynamic forces" I don't think it is aerodynamics. It's pressure inside the boosters being uneven because of the imperfect shape of the boosters. Pressure loves a weak point.

[@hanleypc]

Or the non-circular profile could be the reason the O seals didn't seal correctly if the mating part wasn't the same profile.

[@whoknowsnotme]

It wasn't the aerodynamics, Richard Feynman who helped investigate Challenger said the reason this was significant is because the O-Rings wouldn't have sealed as well if the shape of the boosters warped from the impact of previously being used, but the diameter test might not show that

[@westonding8953]

@@whoknowsnotme he should make a follow up video

[@whoknowsnotme]

Richard Feynman who helped investigate Challenger said the reason this was significant is because the O-Rings wouldn't have sealed as well if the shape of the boosters warped from the impact of previously being used, but the diameter test might not show a change. He also says they weren't even checked to see if the diameter was the same at every point, just a set number of angles, so really they could have warped to all sorts of shapes so long as the diameter was the same at those finite points. So he mentioned these shapes just to cement the argument really, they weren't specifically involved with Challenger.

[@JdeBP]

The diameter test wasn't about measuring circularity, though. It was about measuring the differences between two parts of the SRBs that were to fit together in assembly, ensuring that they did within a tolerance (0.25 inch), *even though* they weren't circular, and in fact were expected not to be. See the Rogers Commission report, pages 58 and 59.

[@patrickvolk7031]

They probably were more checked for straightness than diameter. The O-rings were seated in a tongue in groove joint, which was secured by bolts. They were torqued to a specific spec, which ensures compression on the O-ring to seal the gap. If it's not round, there might be more pressure point on a section of the gasket, but that would extrude into the gaps around it. That is part of the reason for flexible materials for gaskets. There are fiber gaskets, which are more to withstand the pressure on a flat joint (not squeeze out of the space between). You see those on flanges.

[@Anonymousduck161]

I used to work in aerospace machining and for something like that we’d use a radial travel gauge which allows you to check for cylindricality while the piece is spinning in the lathe.

[@superchuck3259]

@@mattmurphy7030 The issue was poor human judgement or alternatively the shuttle was destroyed on purpose to derail the program and stop it. It was expensive after all. Maybe it was remotely piloted. If I am going to theorize, I will not theorize people being intentionally sacrificed.

[@RamLaska]

0:10 Let's please clear this up right now. The Space Shuttle Challenger (as a whole) didn't explode, the External Tank exploded due to hot gases escaping the SRB, and also being struck by the loose SRB. Between the impact of the explosion of the ET and the aerodynamic stresses from losing attitude, the orbiter broke up in the atmosphere. So, parts of the Shuttle (defined as the entire stack - one Orbiter, one External Tank, and two Solid Rocket Boosters) exploded, but not the entire Shuttle. It is quite likely that many or all astronauts survived the Shuttle's breakup, and died when the Orbiter cabin (which had separated from the rest of the craft) struck the ocean. Source: Wikipedia. The article, "Space Shuttle Challenger disaster" is very informative, and well cited. It is a sad and grizzly reality of the Challenger accident, and it's understandable with the authorities of the day repeated the lie that "the Shuttle Exploded, killing everyone instantly." But it's high time to describe the incident accurately. Smith, Scobee, McNair, Onizuka, McAuliffe, Jarvis and Reznik deserve that much. Thanks for reading. I was in middle school when it happened, and only learned of the astronauts fate a few years ago.

[@x_Dude1]

Its true that some were still alive after the explosion.

[@mrsamamorris]

So had the orbiter deployed parashoots they could have survived!?

[@astrodude87]

@@mrsamamorris After Challenger, all Shuttle Launch/Entry Suits included personal parachutes and inflatable flotation rings.

[@paperburn]

@@mrsamamorris They remove the escape parachutes to save weight , the thinking was nobody could survive after passing maximum dynamic stress speed. They were wrong.

[@simontist]

The presence of wings (or large aerodynamic surfaces generally) would seem to greatly exacerbate the effect of losing attitude control: if the angle of attack is suddenly changed to 90°, the G force would be extreme and it would break apart. A capsule is much more resistant to this kind of event, I would think.

[@draygoes]

Well, that explains how it can be a false circle and how they can miss it, but how did it cause the disaster?

[@limerumpus3589]

If fuel cylinders aren’t perfectly round, o rings don’t fasten perfectly which can lead to something breaking under high pressure. If one thing breaks the entire structure can fall apart like a domino row. The reason why false circles matter is that the method of measuring the cylinders that they used can lead to them thinking it’s perfectly round even though it isn’t.

[@lumer2b]

If you make the calculations for spheres and you have weird ass shapes in real life then the calculations are all wrong, of course things can go very wrong as they were never designed to be different

[@SmallSpoonBrigade]

@@limerumpus3589 Which may have contributed, but it hadn't been a problem previously, which leads me to think that it was at most the absolute last straw and more likely not a significant factor as the o-ring was what ultimately let the fuel leak out far enough to ignite.

[@lachlanmcintyre5748]

because everything it setup to be perfectly round, so if its diffirent, nothing fits properly and you get leaks.

[@dialecticalmonist3405]

@@SmallSpoonBrigade Just because something didn't fail previously, doesn't mean it didn't have a significant chance of failing previously. Sheer luck is a roll of the dice and that roll can sometimes fail because of slight variations.

[@petermoore9504]

Richard Feynman demonstrated how the O-rings failed by putting rubber O-rings in a glass of ice water then compressing them with a pair of pliers, they did not return to their normal shape.

[@ChristofferOrrmalmUtsi]

The definition of a false circle like shown in the video above, just done differently, but explain the exact same issue.

[@brianleeper5737]

There's several different types of rubber used to make O-rings and they all have different low temperature properties. A nitrile rubber o-ring would be expected to be stiffer than a silicone rubber o-ring at sub-freezing temperatures. The Challenger o-rings were made of FKM rubber.

[@SylviaRustyFae]

Yes and? Richard Feynman also proposed this possible theory that may have also played a part.

[@SmallSpoonBrigade]

@@SylviaRustyFae The point is that the material that was used to make the o-rings alone would have been sufficient to cause the accident. The false circles may have increased the likelihood of an explosion. But, it's also worth keeping in mind that there were warnings prior to the launch that the weather was too cold for the design specs, that did not include any consideration for any false circles involved, simply that the o-rings could fail due to the lack of elasticity at that temperature.

[@Casualties11]

@@ChristofferOrrmalmUtsi Not at all actually lol. The O-rings that failed were out-of-round, which is not at all what is being explained in this video. In this video he is talking about the rocket boosters themselves being manufactured with a false roundness, not the O-rings being out-of-round. An O-ring not returning to its original shape would not even look circular at all, it would appear ovular and not have constant width. What Peter Moore and Richard Feynman are explaining is caused by embrittlement of rubber at low temperatures creating plasticity.

[@AllenBoudreaux]

Really interesting but not enough explanation of how a non-round shape would have contributed to the Challenger disaster.

[@AllenBoudreaux]

@@Dziaji I don’t think it’s laziness so much as just trying to work within the constraints of the KZbin algorithm which encourages shorter videos in order to maintain visibility…

[@randomescu]

Probably he is saying they put O-rings on non-circle section..thingies. so the orings didnt sealed proper.

[@joshdesellier7275]

The challenger was made to blow up. When we have ways to moniter space travel it all of the sudden vanishes? 😆

[@gordo1163]

@@joshdesellier7275 take your tin foil hat off

[@joshdesellier7275]

@@gordo1163 😆 look.up why we don't go to space anymore, they said "it's because we lost that technology" 😆 seriously just look it up bud, it's in plain sight, def not a conspiracy

[@chrissmalley83]

In addition to the low temperature on the morning of the launch, how could "false circles" have also contributed to the failure of the o-ring joint? Look at the false circle that he drew on the piece of paper. Now inscribe a true circle in that false circle. Now try to fit a constant cross-section o-ring between them to maintain a seal. O-rings are generally good as static radial seals, but false circles illustrate why cross-sectional measurement might not be sufficient to establish cylindricity.

[@bertjesklotepino]

Yeah. Or perhaps it had to do with the fact that it was too cold and the O rings could not handle such freezing temperatures. But Richard Feynman was an idiot, ofcourse.

[@rami-succar7356]

i bellieve it has to do with pressure not being homogene, but i can't be sure

[@justinklenk]

What an excellent, critical point on these (damn🙂) o-rings - and quite well-put, I might add... Thank you for illustrating that principle. 👍 Edit: _cylindricity_ - what a juicy word...

[@ADAMJWAITE]

Circular o-rings are used in non-circular joints all the time without issue. Hell, the whole reason you have an o-ring is to compensate for imperfect connections. It's the purpose they serve. If the joint was perfect, an o-ring wouldn't be needed in the first place.

[@peoplez129]

The reality is the people at NASA knew they messed up and tried to cover it up. There's nothing they could learn from wreckage that would tell them anything. They knew that failure issues were present before launch, but they wanted to launch, because not launching looks bad, but then they realized a failed launch that kills people looks worse. So they played the detective game when in reality they already knew what caused the failure the moment it failed. They just wanted to hide their culpability. NASA is not some organization of the best of the best beyond reproach. They try to make it look that way, but they're not. And that's why this happened. Too many overly confident people who have been patted on the back too many times, that they forget they're not invincible. It's easy to blame the failure on this or that component, but they do that because they want to dissuade from the real failure: the human components in charge of the whole thing. Everyone at the top levels involved in the Challenger disaster should be in prison to this day.

[@alerey4363]

0:58 you should roll the cylinder each time you take a measurement; that way you know it has a circular cross section; otherwise you are just checking "width" along the same position (i.e. you could have an elliptical cross section and you'll never know because you don't roll it to measure)

[@jdmather5755]

That doesn’t necessarily result in different measurements. When I ran a high precision centerless grinder on the shop floor - I would have to use special triangular micrometer to measure cylinder. Sometimes the difference is very subtle and other times you can see out of round visually, but measuring with calipers or even standard precision micrometers would show same measurement at any orientation..

[@michaelz6555]

There were 24 perfectly fine launches before Challenger failed. There were 110 perfectly fine launches after that (although Columbia lost some tiles on STS-113 that led to its disintegration on re-entry). The O-ring grooves need to be ideally circular within tolerance so that shear moments are not placed on the seals such that their performance degrades beyond spec. If the engineers measure roundness at specific points on the SRB, you can bet they're going to include the O-ring seal points at the joints. There were no engineering changes made to the Space Shuttles after Challenger. The only substantial change NASA made in the aftermath was to its work culture. Engineers with boots on the ground knew that the launch temperature was too cold and they recommended a scrub. Higher-ups pressured the engineers to approve the launch because Reagan wanted to make a speech that night about American exceptionalism and the first non-specialist civilian to go into space. And for that, seven people died and NASA suffered a blow that carries with them to this day. After Challenger, NASA decided that the people who actually got paid to do the pre-flight safety checks would be empowered to do their job, including scrubbing a mission without the input of a higher adjudicating authority. False circles on the SRBs were not the problem. Remember your history, please.

[@SmallSpoonBrigade]

Absolutely, the issue was that the launch happened in weather that wasn't in the design specifications that the shuttle was designed for. At most, this may have slightly nudged things towards a disaster, but given how many rockets and shuttles had been launched with this technology that were not affected, it seems reasonable to suggest that it wasn't a large enough contributor to worry about.

[@MattH-wg7ou]

They did make changes to the seals between segments of the SRBs. They added another flange on the inside annular to the seals.

[@SmallSpoonBrigade]

@@MattH-wg7ou Keep in mind that unlike the Soviets, NASA was incredibly conservative about how these were handled, especially after they finished the race to the moon.

[@rapturedmourning]

My college engineering professor discussed this case. He said engineers were 'over-ruled' and it was a business decision to launch. He didn't mention Reagan.

[@michaelz6555]

@@rapturedmourning if you read Richard Feynman’s book “What Do You Care What Other People Think?” on the chapters in which he discussed his service on the shuttle committee, I think he reported that the engineers capitulated under pressure from management, as opposed to management overly overriding the engineers. Shuttle launch managers never previously stood in the way of mission scrubs, and there were a lot of them before STS-25 (although I don’t know if any before were due to low temperature). That means someone at the top definitely wanted that rocket going up. I don’t recall if Feynman mentioned Reagan’s influence in the decision. My guess is that it was oblique at best. But I definitely recall what my dad had to say about it. Back in the day he simply blamed Reagan for the whole thing when the truth came out. It didn’t help that he hated the man’s guts, but it did get me thinking more about the likely chain of events. The head of NASA at the time certainly knew that Reagan would be live on the air with Christa McAuliffe once they were up in orbit, and as a guy who holds a much different balance of engineering and politics than most NASA people, he’d definitely be weighing things differently than the boots on the ground. I don’t blame Reagan. But with great power comes great responsibility, and if he as much as said “well golly, that’s too bad, but you do what you think is best,” I could easily see how that would go from “disappointing but understandable, let’s try again in a few days” to “passive-aggressive encouragement to push for a launch” all the way down to hard management pressure and then capitulation by the engineers. Oops. It’s a form of gossip with devastating consequences. I’m sure wars have been started over less.

[@ExaltedDuck]

"72 seconds after lift off the Space Shuttle Challenger exploding, killing all 7 on board" That glosses over a few important facts that make the terrible event of that day far, far more tragic. The solid rocket boosters are in a constant state of "explosion" as they burn. Even though their break up in turn led to the break of the shuttle, in terms of g-forces, they wouldn't have been all that different from the ongoing operation of the boosters. And the break occurred aft of the cabin. And astronauts wear pressure suits for launching and landing. And the cabin was likely intact all the way to the ocean. There have long been unconfirmed rumors of a radio transcript in which the astronauts remained conscious and continued to speak as the wreckage of the shuttle barreled back down to altitude zero. We'll probably not know for sure for another 20 or so years. But to imagine the possibility and its implications... that makes the day so much worse.

[@postalpacifist88]

while I cant confirm of any radio transmissions i do remember watching a documentary where they stated that some of the emergency air supplies that were connected to the space suits had been activated when rescuers found the bodies

[@stew6302]

6 are still alive 😝😝😝

[@mykalimba]

So for something that is a) engineered to be perfectly round, and b) indeed measures perfectly round using the tests that NASA was using, what is the actual likelihood that it is not truly round because it's become a false circle? Seems like it takes significant effort to engineer a false circle, and thus it's an extremely unlikely coincidence that a true circle goes out of roundness by somehow morphing into a false circle.

[@dmeemd7787]

Rhe biggest reason is the engineers saying it is TOO cold to launch, do NOT launch... buuuut they did it anyway for PR reasons, mainly for a live broadcast they had planned while in space, (and couldn't delay it..or wouldn't rather imo) so NASA pushed it and most of the engineers didn't think it would even clear the tower.. they were almost right when you look at the videos of it... Bad deal through and through 🤦‍♂️ Another really great video!!!!

[@kyle5555]

😔I hope that isn’t true

[@TheZolon]

Wow.. I didn't realize how much of an impact that had on me. Watching the explosion again put me mentally back in front of my TV watching it live.

[@dineshp0305]

Hello action lab!! Thank you for all the information!!😊👍 Can you make more videos regarding aeronautics please? Or fluid mechanics?

[@MysterySteve]

I still can't wrap my head around how false circles just... work. Like I keep seeing them demonstrated and explained, but it's one of the few things in science that legitimately just looks like you have to warp reality as a whole to do it. Wild stuff

[@captdramamine]

thank you for this video. I was in elementary school in Tampa then. the whole school was outside to watch the launch. I didn't fully understand what happened back then. I remember the teachers rushed us back inside and left school out early that day. The "Y" shaped plume stayed in the sky for a notably long time. it was still in the sky when my mom picked us up from school. a very sad day it truly was.

[@midship_nc]

It was poor application of the elastomer. The cold ambient temperature increased the durometer of the orings and they lost their compression in the joint. That is my understanding at least, I have extensive experience with Aflas and it can be very brittle and tough when cold.

[@Blox117]

what should have been used instead? EPDM?

[@midship_nc]

@@Blox117 EPR can work at low temperatures but it may have not been chemically compatible with the booster fuel, or they used aflas because of its chemical range and it can go up to 400F before compression setting. I'm not sure, but obviously they shouldn't have proceeded with the launch and a simple material temperature limit got people killed. It was likely an oversight due to public relations pressure.

[@steveapplegate4565]

@@midship_nc The "cold" temperature shouldn't be a factor, because the rocket encountered much colder temperatures shortly after liftoff. At 40,000 feet, the temperature is about minus 50°F.

[@midship_nc]

@@steveapplegate4565 temperature has a big impact on elastomeric materials though. Challenger had ice hanging off of it before launch. Also after running the SRB's for a while I'm sure there would be heat soak but this would not be effective at launch or for a time until the chassis got hot. Directly after ignition with cold parts, and extreme pressures and forces I could see how an oring could be damaged that would later totally fail once warmed up and everything is expanding.

[@roanysebaert]

Then how do you test if something isn't a false circle?

[@mikehenriksonII]

Dial indicator. Set the dial indicator on the item in question and turn said item.

[@ocping]

That's a very good question... not sure how NASA does it nowadays (Google doesn't really return any good results) but I'd maybe use the method explained to at least prove it's a false circle first. After that, I'd use a circular ring of the desired radius equipped with metal detectors, rotate the ring along multiple sections and calculate the deviations from a perfect circle to be within a certain acceptable error range.

[@JxH]

As far as I've read, there's zero evidence that this otherwise mathematically-interesting finding had anything to do with the accident. At all. Which is the true reason that nobody has ever heard of it.

[@SmallSpoonBrigade]

Definitely, this was the only time this had happened, and we'd been launching rockets based on similar technology for decades at that point without this issue. It's rather unlikely that the extra space that this might have allowed would have been more significant than the lack of elasticity in the o-rings. It may have slightly increased the likelihood of the leak, but not without the launch being conducted on such a cold day with seals that weren't intended to deal with those temperatures.

[@Blox117]

@@SmallSpoonBrigade the difference is that these were reusable rocket boosters that have gone through the stress of flight and landing in the ocean several times

[@SmallSpoonBrigade]

@@Blox117 That wasn't the part that failed though, the part that failed was the o-rings and that would have been replaced between every launch. In the grand scheme of the cost of these missions, the o-rings are pretty cheap.

[@ragingwillie483]

i am always impressed with the way you present a subject, giving a perspective thats not often given. THANK YOU for sharing all you do

[@jacobeng4097]

I love your videos man! Always applying little known science and abstract concepts to the everyday. I can’t wait to use these videos and your teachings to get my kids excited for math and science! Please don’t ever stop

[@renaissanceman5847]

I think we've run across this situation in machine shops with Lathes that have bad bearings and were readjusted to compensate. they turn a cylindrical part... it measures just fine with a micrometer ... but when it placed into a gauge it doesnt fit.

[@44hawk28]

Interesting and informative video. It has literally nothing whatsoever to do with the Challenger disaster. The Challenger disaster was foretold and at least two newspaper articles I read months before it happened. Both of them had talked about how close the solid rocket boosters were to failing. In one launch the solid rocket booster was an apparent failure mode and had blown out the side of it at one of the seams seven seconds after it Departed the launch vehicle. That was getting dangerously close to failure. When they redesigned the seal they did not change it markedly the same basic design was still in use they added an extra o-ring and put it at a different stress point. I was working on that day and a friend of mine came up and stated that the Challenger had gone down and I told him instantly that it was probably the solid rocket booster failure that had caused the failure. And I told him then about the newspaper articles I had read several months before that. The fact that the Engineers who built it say stated numerous times before it took off that it would fail because the O-rings would not be at a temperature in which they could even possibly make a seal consistent exacerbated the issue. But the primary issue was the fact that it had a temperature range which was required to be maintained in order to have a successful launch and nobody decided to follow that advice that had any decision on whether or not to light the fuse.

[@Chironex_Fleckeri]

Weird to insert your own ego into a comment that mightve been insightful or interesting. Did you write the book, "Everything I Say is Right" ?

[@KakuiKujira]

@@Chironex_Fleckeri He may have read that book, but it was written by my wife.

[@Chironex_Fleckeri]

@@KakuiKujira lmao

[@mbox314]

Geometric dimensioning and toleranceing (GD@T) is supposed to address this problem. When you make a part with a cylindrical shape you do not simply provide a diametrical tolerance, you have a diametrical tolerance with a circular tolerance zone, a surface profile, Run out tolerance or another tolerance zone that is referenced to a set of datums. Inspecting in this way creates an imaginary volume in space that the part can exist within while still functioning according to design and a huge part like an SRB casing would have almost certainly been designed and inspected with this in tolerance scheme.

[@DrHarryT]

You didn't explain how a "non-circular diameter" could have caused the booster to burst??? O-Ring testing revealed that micro-fractures would form at low temperatures. One of the engineers complained about the problem in a pre-launch conference call and his opinion/data was squashed.

[@Assorted12]

Interesting, but how would the boosters being non-circular have resulted in the explosion? Thanks for the video!

[@frankb3347]

Uneven pressure.

[@aliensoup2420]

In any complex system there can be multiple points of failure that are not directly apparent or directly related to the primary failure. The Apollo 13 accident is a case in point. Anyone that writes simple computer programs is familiar with this concept.

[@eloiseharbeson2483]

"How Round is your Circle?" by Bryan and Sangwin goes much deeper into this and related questions.

[@sundownermgr]

My great grandma worked on the Challenger's motherboard's, so after the catastrophe, my mom and her sibling would joke with her, sayingthat she rigged the motherboards (obvious joke meant to cope with the disaster after the initial shock.) Thankfully, she always kept a cool head and wasn't angry at them for joking about it, best grandma ever imo

[@Idaho-Cowboy]

So cool, most of what I've heard about the Challenger has been in the context of not calling it off based on the temperature and the known O ring failure. Never knew there could have been other issues contributing to a bad seal and disaster.

[@torydavis10]

I mean, it's technically true, but any potential unroundness would only really have contributed to the severity of the known, stated, and ignored problem. The singular reason people died is still the decision to launch on that day.

[@adamhale6672]

This is all hearsay. The steel rocket casings used in the SRBs are manufactured on an enormous lathe. The test engineers in charge of this process don’t use calipers to “measure the diameter“. A feeler gauge is run around the perimeter to test for deviations from roundness. This is done at multiple points along the body to test for cylindricity. I don’t know what source this guy gas, but what was demonstrated does not at all reflect how measurements are taken.

[@jmd1743]

The person who refused to call it off ended up being promoted for the way she handled the disaster clean up. NASA is a failure because it has people think they're better than the engineers because of their leadership Hierarchy. None of them have skin in the game as well. Boeing is in the mess it is today because they allowed Douglas Aerospace's middle management to replace the engineering culture. I honestly think that Airbus, Lockheed, and Boeing could become flexible like SpaceX.but It's going to take big pocket activist investors to get those companies back into shape & into the right mind set.

[@imnotsubbingtoeveryonewhos7996]

Imagine a bowling ball with this shape

[@YHDiamond]

That wouldn't work

[@billharm6006]

Never heard of this. Wonderful explanation. I just wish you had linked it to possible failure modes.

[@riddle672]

We face similar basic problem in Centreless Grinding process, in shop floor terms we refer it as “Lobing”. Its basically roundness of the part, form parameter. Can easily be overseen if we do not know about this problem. It will have major effect where fitting or assembly areas.

[@unvergebeneid]

If someone warned about a possible O-ring failure due to the temperature and the O-ring failed due to the temperature, why do we need a second possible explanation on top of it?

[@whoknowsnotme]

My speculation would be that it added to the instability and perhaps contributed to the clog of char (which initially stopped the leak) coming loose, which is what ultimately caused it to break apart. Would like to know for sure though.

[@jcskyknight2222]

We don’t know for certain that that was the entire cause. This particular issue came up during the investigation as a possible contributing factor.

[@unvergebeneid]

@@jcskyknight2222 I mean, if am engineer raises the alarm _beforehand,_ gets ignored and then the thing explodes, that's pretty strong evidence that he was on to something.

[@jcskyknight2222]

@@unvergebeneid I believe they raised the true circle thing beforehand as well. The people overhauling the booster parts could see the parts were well out of shape even though they were passing the checks.

[@unvergebeneid]

@@jcskyknight2222 well that would change things. It's the first time I hear about it. Would've been nice to get a bit more info in the video :/

[@RobertTempleton64]

That's a sad way to determine roundness (circularity) and cylindricity since it only does a two-point diametric check at each circle. You would think that they would have a large gantry CMM which could do multipoint circles to get a realistic measurement of this feature control or at least do multiple diametric measurements around each circle.

[@dntfrthreapr]

i dont think they had CMMs in the 1970s tho when Challenger was built

[@RobertTempleton64]

@@dntfrthreapr Yes they did. First CMMs in 1959.

[@dntfrthreapr]

@@RobertTempleton64 interesting

[@mbox314]

@@dntfrthreapr Sperry was building CMM machines in the 1960's but GD&T was developed before CMM machines existed, everything can be measured with gauges, fixtures, indicators, jigs and maybe an optical comparator if you are fancy.

[@OverlandOne]

This is why machine shops us V-Micrometers. When using a centerless grinder, if you drift below center you can generate a shape that will measure perfectly round on using a regular micrometer but, it you check the parts using a V-Micrometer, you will easily see it is not round at all. Any machine shop will have V-Mics for just this reason.

[@bozhijak]

Mt. Hood Oregon?? Every once in a while i come across jems like this. Thank You!

[@Sashazur]

Is this a real cause identified in the investigation? I never heard of this. Engineers knew the o-rings had a high risk of failure if the launch took place in cold weather. They told this to NASA mgmt (though their presentation could have been clearer), and mgmt went ahead with the launch anyway - and the result was disaster.

[@adamhale6672]

This is absolute hearsay. The steel rocket casings used in the SRBs are manufactured on an enormous lathe. The test engineers in charge of this process don’t use giant calipers to “measure the diameter“. A feeler gauge is run around the perimeter to test for deviations from roundness. This is done at multiple points along the body to test for cylindricity. What was demonstrated does not at all reflect how measurements are taken, and the actual process does not have those issues. I would love to read what sources he is getting information from, but none are listed. There is zero significance in this as a cause of the challenger disaster.

[@kickassnetwork]

If you don't mind me asking. I didn't know what a feeler gauge is till I looked it up, but how is that used to determine roundness? From what I found out it measures gaps. Do you know the process by how they used that to measure?

[@Num6er47]

You can't determine roundness with a pair of calipers

[@kindlin]

@@kickassnetwork I don't think what you get when you google Feeler Gauge is what he's talking about. I'm familiar with a methodology that just uses a simple roller on an actuator that measures the distance till the roller contacts. As the piece is rotated over that roller about its centroid, if the piece was perfectly round, there will be zero movement in the roller. It would probably be easier to do it on the sides so that gravity flexing is less of an issue, or from a standing position. But there are definitely ways.

[@ScottHz]

This is what Feynman was pointing out - when recertifying the used SRB shells, they were implying that they were within a tolerable ‘roundness’ by measuring a few diameters around the cylinder, which did not logically follow (having constant diameters doesn’t guarantee that both pieces of the SRB will have a gap within the original design specification).

[@ScottHz]

His source is likely “Surely You’re Joking, Dr. Feynman”

[@markg7963]

Just subscribed. Nice guy, interesting stuff, and straight to the point without fluff! Thanks.

[@DaveVelo1]

If my memory serves me right, Richard Feynman concluded that freezing temperatures caused the O ring seals used on the boosters to fail.

[@Generic-Cat-Drawing]

What did the triangle say False circles? “Is this how you roll?”

[@Atlas.Brooklyn]

Even with the edit, this barely makes sense.

[@jatishgupta3497]

HAPPY INDEPENDENCE DAY to every indian 🇮🇳🇮🇳🇮🇳🇮🇳🇮🇳🇮🇳🇮🇳🇮🇳🇮🇳🇮🇳

[@mreventos]

And to every cowboy as well ...🐴

[@kyle5555]

Aw very cool! Happy Independence Day. Who are you guys celebrating independence from?

[@jatishgupta3497]

@@kyle5555 obviously britishers (Britain) who ruled our country for more than 200 years

[@kyle5555]

@@jatishgupta3497 damn. They ruled everybody at one time huh? Lol

[@5alpha23]

I have watched your videos for years now - interestingly enough I find this one the most eye-opening yet. 😁

[@elonfc]

Hey action lab , i love to watch your video and what i wanted to say you is that keep educating people about beauty of science,. Well done . Thanks Your subscriber

[@simonkormendy849]

Actually, it was a faulty O-ring on one of the Challenger's rocket engines, that had frozen and cracked, which caused the Challenger disaster.

[@dmeemd7787]

Exactly, and the engineer said do not launch but they did it anyway for PR reasons for a live broadcast they're supposed to do from space, but NASA pushed it and most of the engineers didn't think it it would even clear the tower

[@100to210]

@@dmeemd7787 yep, they were warned, but NASA still went through with it, and sadly those crew members lost their lives.

[@u1zha]

Are you a fan of single cause fallacy? James mentioned o-rings already, rewatching the video is recommended.

[@TOKEN511]

This is some hyperdimensional projection matrix level stuff here. It's always the same width, even though it's not a sphere. Had to see it to believe it.

[@mike1024.]

A sphere has a constant radius and thus a constant diameter, but having a constant diameter does not mean it has a constant radius!

[@chrisspence6484]

Engineers work with this problem all the time. The challenger engineers would have defiantly known and measured the joints of the rocket to take account of the lobing. (That is what we engineers call it) During manufacture there would have been a geometric tolerance stated on the plans (ie flatness, roundness, squareness, perpendicularly and so on). This does not mean that corners weren’t cut or stated tolerances too great.

[@Tker1970]

My biology teacher, Kathleen Beres, was one of the top 10 finalists for the teacher in space program. We were all watching in the auditorium of Kenwood High School that day. The room was absolutely silent when we realized what happened.

[@bethmaldonado9241]

First

[@sussnoo4081]

Things

[@judeissac7645]

*Investing in crypto now should be in every wise individuals list, in some months time you'll be ecstatic with the decision you made today..*

[@kennethmills2607]

Please how can I contact Mr. Joseph Lubin? I really like what he has done for you, and I also want to benefit from it.

[@kennethmills2607]

@Carletto F THANKS A LOT I HAVE CONTACTED HIM NOW AND HE'S RESPONDED

[@eightmilesupwind9030]

This is so awesome! Thanks for the beautiful demo.

[@runenorderhaug7646]

To be honest, an issue you didnt mention is one of the challenges that to some extent is the biggest to overcome. The reality that pretty much you can only minimize the extent to which it is a false circle rather than truely ever having identifical circles because in the real world pretty much even perfectily matching thing will be slightly varient to some level

[@simontist]

That's why engineering is all about tolerances. So long as the design can handle any defects smaller than the measurement method used (which itself has a known level of accuracy), the design can be assured as safe. This is quite complex to achieve in practice, though.

[@ifpikachuhaddrip2197]

things humans were never meant to see We're no strangers to love You know the rules and so do I (do I) A full commitment's what I'm thinking of You wouldn't get this from any other guy I just wanna tell you how I'm feeling Gotta make you understand Never gonna give you up Never gonna let you down Never gonna run around and desert you Never gonna make you cry Never gonna say goodbye Never gonna tell a lie and hurt you We've known each other for so long Your heart's been aching, but you're too shy to say it (say it) Inside, we both know what's been going on (going on) We know the game and we're gonna play it And if you ask me how I'm feeling Don't tell me you're too blind to see Never gonna give you up Never gonna let you down Never gonna run around and desert you Never gonna make you cry Never gonna say goodbye Never gonna tell a lie and hurt you Never gonna give you up Never gonna let you down Never gonna run around and desert you Never gonna make you cry Never gonna say goodbye Never gonna tell a lie and hurt you We've known each other for so long Your heart's been aching, but you're too shy to say it (to say it) Inside, we both know what's been going on (going on) We know the game and we're gonna play it I just wanna tell you how I'm feeling Gotta make you understand Never gonna give you up Never gonna let you down Never gonna run around and desert you Never gonna make you cry Never gonna say goodbye Never gonna tell a lie and hurt you Never gonna give you up Never gonna let you down Never gonna run around and desert you Never gonna make you cry Never gonna say goodbye Never gonna tell a lie and hurt you Never gonna give you up Never gonna let you down Never gonna run around and desert you Never gonna make you cry Never gonna say goodbye Never gonna tell a lie and hurt you

[@Ryanisalive]

Cool

[@IM_ROZZ_YT.O1]

Let's w a moment to appreciate how much effort he puts into his contact to entertain.♥️🙂

[@AwesomeotasticGaming]

really cool! You gonna do a vid on how to actually test roundness?

[@universalparadoxes2081]

Thanks for teaching me something I had never heard of or thought about before.

[@zzstoner]

The example you did using classic geometry was really cool. 👍 I don't think I've seen another video about 'shapes of constant-width' dig into the mathematical reasons _why_ ... other than showing the given shape has a constant width.

[@johnchristopherrobert1839]

Loved this content. It blew my mind, great stuff!

[@jayski9410]

I can't believe I've gotten to 70 years of age and never heard of false circles. This ranks right up there with mobius strips and Klein bottles, which I have heard of. I've even seen a diagram of a Calabi-Yau manifold but no false circles until now. Thanks.

[@pb5109]

Some questions, 1. How do you properly test that a shape is circular vs non-circular? 2. Is the only way to test against this by measuring from the center? 3. How could these non circles have affected the spacecraft? (even if not correct, a good explanation can open up some debate)

[@mikefochtman7164]

I believe you can measure the diameter at several positions, AND measure the circumference. A 'false circle' would have a larger circumference than a 'true circle' of the same diameter.

[@anthonykeller5120]

Loved to learn about false circles and how to make them. Would love to see how the false circle solids are designed and made as well. Sounds like a very interesting project. At this late date apportioning Challenger disaster blame is kind of like playing “Who Shot Kennedy”.

[@giannijimenez5684]

I used to go to a school named after that ship, we had to learn about it like once every year but it was actually pretty cool to learn all that stuff about it

[@Equinoxcz]

Is there a 3D print file of it? This seems like another fun. Thank you Action Lab

[@roberthoffman4713]

Wow I think at one point in time they replaced the tires and rims on a pickup truck with something shaped like the copper piece you have and it seemed to roll fine. I think they tried some other shapes also and some at low speed were pretty bumpy but as the speed picked up it smoothed out. It's cool and I think more impact full when you can see what is being shown or talked about with visual aids.

[@garymutunga3187]

Always learning new stuff here 💯💯

[@hexadecimal7300]

Thankyou I learned something as usual. Great channel

[@Troyster94806]

It doesn't even take an engineer to know that they launched too cold.

[@whatworks3006]

This is fing insane dude I love this video and would like to see more like it

[@XploringMyself]

Each new day has a different shape to it. You just roll with it.

[@HyperHrishiHD]

When those noncircular ball shaped “balls” a rolling smoothly, it gives me satisfaction 😆

[@truckerenoch8824]

I was in third grade when our principal came in and told the class about the accident. Sad day!

[@thirteenthandy]

I'd really like a much deeper dive on how this concept could have affected Challenger. I can't find anything related to it elsewhere.

[@sheepthevampire5413]

That's really cool, but yeah, there's a whole bunch of rules that just exist to confirm how parallel, round, spherical, etc something is. The measurements are so specific that it's mostly only added to really confirm if it's the correct geometry to keep costs down. We're talking about micrometers, the same unit used for fittings and specific tolerances. Those likely came up in part of the accident but also in part because machinery becomes more specific every day.

[@originalprojdw6523]

Information on how to fix this would be really neat

[@georgeslater2875]

Makes sense. Cavitations causing uneven burn/propulsion/exhaust, chaotic turbulence over heating the sleeve, causing expansion of the trapped air in further cavitations, pressure breaks the solid fuel, spark set gas alight.

[@davidanderson5310]

- How does a non-circular booster casing cause an explosion? - *Were* the boosters actually "out of round"? They could look at the boosters on the other shuttles to check.

[@TURPEG]

They couldn't check really, 2 shuttle don't have their own pair,

[@davidanderson5310]

@@TURPEG True; I knew that but I was simplifying for the wider audience. I suppose I could have just said "other boosters", but I wanted to preempt the question "what other boosters?". Likewise I didn't want to use any jargon like "SRB casing" or "field joint" that James hadn't introduced in the video.

[@ABaumstumpf]

You forgot to mention HOW that could have affected Challenger.

[@cadechristopher6456]

I saw the Challenger explosion in person. I was in 6th grade at Sea Park Elementary School in Satellite Beach, Florida. My science teacher brought the class out into the parking lot to watch the launch. Because I had watched many launches before I knew something was wrong right away. Mr. McGovern, my science teacher began crying as he ushered us back inside. I had never even thought about death before that day. I have a very vivid memory of the experience.

[@Scardpelt]

I knew someone who worked for DuPont and her only job was having her eyes under a microscope inspecting these O rings for NASA in 2010s She recounted that the general consensus (unofficially) was that a large amount of human error was responsible for the improper orings, and that her job was of good value (and damn good pay)

[@seanjournot7115]

I've seen this before machining parts on a cnc lathe. Chuck pressure was too high and it was deforming a series of parts which were then machined with a cylindrical feature. After running the parts they had a tri-lobed shape which looked good when checked with micrometers or calipers but was obviously out of tolerance when checked for total indicator run out on a V block. This can be a serious issue since it could obviously lead to interference, or out of tolerance clearance, fits between mating parts and has a good chance of not being noticed.

[@wayland7150]

I bet there are some really interesting applications for these. What would happen if they were used as ball bearings? Perhaps as a cam profile?

[@BADALICE]

What you're saying is the astronauts didn't know how to measure the diameter of circles during lift off. I never thought about that. You draw a great triangle by the way. Excellent video, very informative.

[@allen_p]

Very interesting video. First time hearing of false circles. As a commercial HVAC tech I could see how this could be problematic in my field.

[@shivamsharma-ey7hg]

I wish you would include how to detect false circles

[@readtruth6670]

Those shapes look like what often happens to worn down ball bearings. They function well enough… until they don’t.

[@JMWexperience]

Very interesting! Thanks for sharing.

[@TS_Mind_Swept]

While fasting, I can't help but feel like that left more questions than answers..

[@TheOrigamiGenius]

Those shapes are so trippy

[@spiritofthewolf15x]

This was very informative... I don't know WHY it came up in my feed, but I'm glad it did.

[@elijahmitchell-hopmeier182]

Came for the circles stayed to see the challenger disaster

[@Graeme_Lastname]

Some bureaucrat said "Damn the temperature, we launch anyway."

[@sundayridetexas416]

"Exploded" is the incorrect term. The Shuttle tank rapidly depressurized and seperated from the Challenger. Then the aerodynamic forces finished off everything. This was a rapid expansion of gases, not a combustion explosion.