Saturn V Staging, Asteroid Deflection and Hearing Rocket Turbines - Supporter Questions, Episode 17

[@travcollier]

Ooh, fun airplane fact. Old large aircraft (like bombers) would often have a star sighting scope + sextant on them too. Navigator used to be a very important and pretty hard job.

[@johndododoe1411]

Yeah, the star sighting windows on some types has been converted to a satellite antenna window on some models.

[@dannykoop]

Earnest K. Gann mentions them, I think, in Fate is the Hunter. I think for aviation they were called octants

[@fredwood1490]

Just a silly thing but the Crews of those old bombers often referred to the Navigator as the "Naviguesser" because of the often less than perfect guidance they offered. On ships there would be three people making he sightings, then they would be averaged but bombers only had the one. Thanks for the GPS systems and somewhere near close accuracy today!

[@ItsReallyJackBlack]

The SR-71 had one. It navigated by the stars.

[@gbcb8853]

Erroneous star navigation was partly responsible for the crash of G-ALDN in North Africa in May 1952

[@wdavidwoods]

Thank you for the mention of the book, Scott. Hoping you don't mind but I can clarify the answer to the Saturn V skirt separation question a bit. The reason they hung onto the interstage ring for 30 seconds wasn't to hang onto the ullage motors. In fact, from Apollo 15 onwards, those ullage motors on the ring had been deleted. The second stage tanks were full anyway and their internal pressure provided sufficient head to feed the engines. The reason they hung onto the ring was because the clearance between it and the engine nozzles on the second stage was a bit close. The fear was that if there was enough rotation of the two halves of the vehicle as they separated, there might be a risk of the skirt striking a nozzle. The plan was to allow the second stage to ignite and settle into its burn. By 30 seconds, the control system would have damped out any major rotation and the stage would be accelerating briskly. The ring would be cut adrift, allowing the stage to accelerate away from it before any rotation would have a chance to cause it to hit an engine.

[@MattH-wg7ou]

I absolutely LOVE my "Haynes Manual" for the Saturn V!

[@MattH-wg7ou]

@@toonarmycaptain He wrote the book. I'm sure the primary NASA source is in there, but I am traveling and dont have access to it now.

[@marcogenovesi8570]

@@toonarmycaptain I think he is the actual writer of the book "NASA Saturn V 1967-1973 " mentioned in the video at 3:24 the name and profile pictures match

[@CardZed]

Wasnt the ullage motor count only reduced, instead of deleted entirely? I remember reading that before Apollo 15 it had 6 motors, afterwards they took that down to 4

[@scottmanley]

Fantastic, thanks for clarifying!

[@milstarr]

One very obscure fact about the interstage: During the launch of the Skylab workshop, the interstage failed to separate because some of the separation charges were damaged by the aerodynamic incident that occured during the S-1C burn. Luckily enough tension straps remained to hold the interstage in place otherwise it could have partially separated and affected one or more of the S-II's engines while they were burning.

[@CardZed]

The blocks of lead "hidden" inside the interstage also did not come off so Skylab reached orbit with more weight than expected. (Blocks of lead were there because Skylab was lighter than the Apollo configuration, which would have made the center of mass way too low for a safe floght)

[@calessi]

Worse yet was the amount of thermal energy building up amongst the J-2 cluster due to the lack of skirt separation. NASA later calculated that the S-II thrust bulkhead was within moments of imploding due to an amount of heat build-up which it was not designed for. In a manned Apollo mission, the failure of the interstage to separate cleanly would have required an abort. In any event the partial separation of the skirt during the Skylab I launch was such that the vehicle never properly registered the failure; from a systems standpoint the interstage had cleanly separated, when in fact the separation was only a partial one.

[@robertbutsch1802]

All these replies suggest how tight the Apollo lunar missions probably were when it came to weight. A separate interstage separation was just another potential failure point, so why include it? I suspect SpaceX would never include such a feature on the Falcon 9 (or if they did Elon would nix it pronto). The ullage motors probably were massive enough by themselves that the Saturn V might not have been able to get the mission to the surface of the Moon and back to Earth again if they weren’t shed as soon as they weren’t needed anymore. So the added risk of a failed interstage separation was worth it.

[@calessi]

@@robertbutsch1802 the dual-plane separation was needed because of the tight clearance between the J-2 cluster and the interior of the interstage. The SI-C was quite massive. Any yaw or pitch imparted to it as it slid away could cause it to collide with the J-2s if the interstage were fixed to the top of the SI-C, resulting in a catastrophic end of the mission and an abort. With an interstage that separates on its own several seconds later after the J-2s had completed their initial gimbaling, that danger was negated.

[@nicholasmaude6906]

@@calessi This!

[@nubnubbud]

"why did the saturn V drop its ring?" *looks up, holding back tears* "if you wait long enough, every saturn loses its rings."

[@Najolve]

*looks down, holding back tears* "I hope that applies to spare tires as well."

[@allanrichardson9081]

Because it discovered its fiancé was cheating?

[@ChemEDan]

@@allanrichardson9081 Saturn's rings are eroding - current estimates say they'll be gone in like 100 million years which isn't much compared to the age of the solar system itself.

[@SomeRandomGuy_id]

Well said.

[@Metallica4Life92]

that was beautiful

[@exospaceman8209]

The ring coming out from the 2nd stage is the most iconic thing from the Saturn V

[@concon3055]

Not “one small step for man…?”

[@HowToSpacic]

@@concon3055 that’s more about the Apollo program itself, this commenter is talking about the launch vehicle specifically.

[@fork9001]

And, it’s on every configuration and mission ever flown. Even on Skylab 1.

[@HowToSpacic]

@@fork9001 was it on Skylab? Skylab wouldn’t have needed the ullage thrusters to provide continuous acceleration because it took the place of the S-IVB upper stage, was there a modified skirt section for that mission?

[@travcollier]

It was less of an interstage than Stage 1.5 ;)

[@Lucerne9]

Do a big 1hr+ catch up! I love hearing your thoughts on this stuff and the level of knowledge you share w KZbin

[@firefly4f4]

Another obvious case of hearing the turbopumps starting is the Raptor vacuum engine test that you covered previously.

[@Atlas_System01]

I’m not completely sure about this but I think you can hear the shuttle turbo pumps firing up during launches but I’m not completely sure. If only someone could verify this

[@Katniss218]

The actual reason for the dual-plane separation on the S-II was that the engineers had concerns that the vibrations caused by the 1st stage would make the interstage bang on the engines (since there wasn't much room around them). The interstage was then jettisoned after the engines stabilized burning and the vibrations were under control

[@jamest18]

I believe this is correct. Although I'm sure they were keeping the ullage motors in mind when designing it.

[@malcolmbacchus866]

That's the reason given in "Stages To Saturn". NASA SP-4206 or NASA 033-000-01176-8.

[@Katniss218]

@@jamest18 Yeah, I think so too, it is a nice place to put them, where they won't constitute dead weight

[@takashitamagawa5881]

I've seen interviews with Apollo 8 crew members Frank Borman (Commander) and Bill Anders (Lunar Module Pilot) where they both described the violence of the SI-C - SII staging event. The astronauts were thrown forward against their restraints as the first stage engines cut off, then thrown back into their couches as the ullage motors and second stage engines were activated. No two vehicles so massive or bulky had ever been separated in mid-flight up to that point in time. Yes, there were plenty of unknowns about what vibrations and other mechanical motion modes could occur and about what damage could thus result during staging.

[@heythere135]

@@takashitamagawa5881 it’s crazy how many things had to work perfectly just to stage. S1C outboard engines cut off, milliseconds later both the printer cord and second stage ullage motors fired, milliseconds after that the S1C retro rockets fired while simultaneously the engine start command for the SII was given and all engines had to start perfectly and at the same time. So many violent events, preceded by a violent boost phase from the S1C full of transient vibrations. The engineering to pull just THIS off is mind blowing. And that’s not to mention literally everything else pertaining to the Saturn V and Apollo program

[@elmurcis1]

Loving to see casual "Saturn V owners workshop manual"

[@AdamJRichardson]

I'll have to get one to go along with my Thunderbirds workshop manual, also from Haines

[@esoteridactyl]

@@AdamJRichardson I have the Apollo one. They have a bunch of different ones related to Saturn/Apollo era. I'm not sure what the differences are for example mine vs Saturn V.

[@GenasysMech]

Having obtained my private, then commercial and instrument ratings in the late 70's, early 80's on "six packs" only, when discussing HSI drift, very few today recognize the significance of slapping cams up everywhere in and around the cockpit, particularly the panel cowling and the effect this has on the magnetic compass. Various cockpit configurations at production is the reason for the "Deviation Card" attached to the compass as each aircraft is unique in respect to magnetic field "anomalies". Further, most airports have an official "Compass Rose" painted on the pavement in a remote area of the ramp so you can taxi on to it and with the engine running, electronics all on, aka "in flight mode" confirm you mag compass accuracy. It can be a big deal when truly flying VFR only. A lot of the "RNAV" equipment back then had sensors remotely located to a specific area of the wing because of this issue.

[@raykewin3608]

It's a baren wasteland without your work, Sir.

[@martinrwolfe]

One of the ways that improved the performance on later Saturn V missions was a reduction of the number of ulage thrusters on the insterstage with them eliminated completely on the last few flights that included those with the rover.

[@slaphappyduplenty2436]

How did they eliminate ulage completely?

[@martinrwolfe]

@@toonarmycaptain It is mentioned in the instructions for for the 1:133 Revel model kit. Alos on wiki and the Saturn V owners manual

[@martinrwolfe]

@@slaphappyduplenty2436 I belive it is a combination of residual atmospheric drag and exhaust from the prechill on the J2 engines on the second stage. Does not take much to keeep the propelants settled.

[@jursamaj]

@@martinrwolfe Any atmospheric drag would have pushed the fuel up, not down. As David Woods mentions in another thread, the pressure in the 2nd stage tanks was enough to start the engines.

[@wrightmf]

I read some place that Saturn V had a huge amount of capacity, some ways over engineered so it could lift more mass on later Apollo missions. Launch vehicle can accommodate extra mass but spacecraft itself needed additional capacity.

[@joeschmalhofer6109]

The reason for the 2nd stage skirt was because there are 5 engines on the 2nd stage and they didn't want to drop the skirt until all 5 had lit and were not moving around trying to stear the stack. This info was stated in several NASA documentd.

[@MonkeyJedi99]

You definitely don't want to drop your skirt too early. Giggety.

[@iamjadedhobo]

Termination Shock is a *must read* It doesn't just explore the technical aspect of geo-engineering, but delves deeply in possible geo-political consequences. Who stands to win, and who stands to loose and why would an historic city-state want to go rogue again.

[@paulhaynes8045]

I love the way I get answers to questions I didn't know I had! Definitely the best space nerd channel - by a long way.

[@randalscott7224]

Re the space elevator and Mars. Clarke covered that in "The Fountains of Paradise" where the enterprising Martians (humans born and raised on Mars) wanted the elevator built using Mars' outer moon Deimos as a source of the raw material and as a counter-balance mass. They even had a solution for avoiding Phobos, Mars' inner moon by sending a payload up that flexed the tower in a similar manner to a guitar string. Clarke's hero was amused by the Martian's idea of turning this into a tourist attraction, imagining Phobos sailing past just a few km from the passenger car!

[@danieljensen2626]

The Red Mars trilogy has something similar, probably inspired by Clarke. In fact now that I think about it, they use an asteroid called Clarke, so that's a pretty obvious nod.

[@aaronmicalowe]

The problem I see with all of these engineering challenges is that it wouldn't take much for something to crash into it creating a chain reaction that would cause the whole thing (and everyone on it) to come crashing down. Ideally it would need to be some kind of self repairing material that could also avoid disasters. Perhaps some sentient AI quantum level exotic substrate operating partially outside of physical reality. By the time we got to that level it'd be easier just to beam people's souls up in a jiffy.

[@jpchan23]

David Brin wrote a short story called tank farm dynamo that posits a much smaller space elevator that moves space craft from say low earth orbit to higher earth orbit. I wonder how much more practical that would be compared to a ground to orbit type space elevator.

[@RS-ls7mm]

A space elevator might be possible but not while there are people around. Its too big of an opportunity for terrorists.

[@MattMcIrvin]

@@jpchan23 There was Hans Moravec's idea of a rotating cable whose ends would describe cycloids as it orbited the Earth--at the low end, it could grab onto a payload and yank it into space, but you might want some kind of counterweight object going in the opposite direction. I tried using that in some of my amateur science fiction.

[@dakotahrickard]

I always listen for the turbopumps to spin up. It helps me know what's going on as a blind viewer. You can hear them on a lot of the test videos. Sometimes, the spin-up is a quarter of a second. Makes me wonder at the materials sciences here, as the pump has to handle the torsion forces, thermal variances, and fluid loads. Guess that's why being a rocket scientist is kind of a big deal.

[@ValentineC137]

The first question was actually about a spacecraft heading for impact with fuel onboard, would burning that fuel to increase the impact velocity add more energy than just keeping the fuel onboard to increase the mass of the impacting rocket

[@MattBond00797]

That was my interpretation too

[@HarzemTube]

Exactly, Scott misunderstood the question.

[@joshuacheung6518]

Well. Your intercept orbit could end up just gently grazing the target at like 1m/s... which would be equivalent to what scott was talking about But yeah, i also agree he misunderstood

[@desilove007]

Burning the fuel to increase velocity will impart more energy on impact. Specific Impulse basically means how much velocity can be added by burning a certain amount of the fuel. So if a rocket had a mass of 3kg and initial velocity of 1 mps then momentum is 3kgmps. If we burn 1kg of fuel and the new velocity is now 2mps then the total momentum is 4kgmps. So there will be more energy transferred on impact.

[@Andrew-13579]

Could this be a valid analogy: If you drop a 7.62mm rifle cartridge 1m to the ground will it hit with as much momentum as if you put it in a rifle and fired the projectile into the ground? In this case the mass of the propellant (and casing and primer) is far less important to momentum than the velocity given by combustion of the propellant to just the projectile.

[@praetorfenix69]

The other issue you didn't point out with servicing JWST: it's not in LEO, it's orbiting the L2 lagrange point. No current spacecraft is capable of travelling outside of LEO and Orion certainly isn't intended for servicing sattelites

[@applesaregoodeatings]

Crew dragon on a falcon heavy. But there is no was NASA would let that happen

[@slaphappyduplenty2436]

Robots could be sent out there. Also, I can’t imagine it be impossible to send out a “backpack” with cold gas thrusters which could affix itself to the sun side of JWST and keep it in orbit. Of course, by then a new and better telescope could be developed and sent out to relieve it of duty.

[@slaphappyduplenty2436]

Heh. Should’ve watched the video first 😬

[@_K3PLR]

@@slaphappyduplenty2436 im not sure if a servicing mission would even be feasible. JWST to my knowledge, just doesn't have the hardware for servicing, that milimeter thick, delicate sunshield would not do well against any engine firings. A new telescope with designed with serviceability in mind would be the better option.

[@randomnickify]

@@applesaregoodeatings It took jwst almost month to get there, good luck sending astronauts on mission.

[@allanrichardson9081]

I don’t see any other comments on this subject, but one way in which the military - and politics - complicated the design of the Shuttle was in the manufacturing site of the SRBs. The original plan was to build the SRBs in one piece near Woodbine, GA (about 15-20 miles north of the FL line on I-95 or US-17), and float them on barges down the Satilla River, then south on the Intracoastal Waterway (the gap between the mainland and the barrier islands) to the Cape. Simple design, fewer steps to fabricate, and NO O-RING JOINTS. But the military wanted a polar orbit launch site in the CA desert, so they had to be transported by land. And Morton Salt, based in Utah, bought the manufacturer Thiokol, and lobbied Utah’s Congressional delegation to push for moving the factory site to Utah. This meant that the SRBs had to be moved by rail, requiring them to be made in three pieces that could be put on a rail car, leading to the O-rings that failed and led to the Challenger tragedy. And for every launch they had to be moved from Utah to Florida by rail, rather than from southeastern Georgia, and never once got shipped to the California launch site which was part of the reason for the design change!

[@LordMarcus]

Scott Manley is morphing into Captain Picard as the years go by. I remember finding this channel years ago via KSP, can't remember the version but you were playing a science mod that would let you achieve warp propulsion. 9 years ago? Maybe 10?

[@General12th]

Interstellar Quest?

[@ApocolypseChild]

Indeed, JJ is probably right that it was interstellar quest. The only other one I can think that it may have been was Galileo Conquest but that's only because I don't remember the details of that series quite as well.

[@aaasss4077]

He's French?

[@awilliams1701]

interstellar quest and it was pre-beta and beta. He had tons of problems with it.

[@lordbored2706]

M'lord

[@dierbloodrose5178]

I hadn't even thought of 100 questions in one video 🤔, but now that you said it I want it. 🎉🎉

[@samuraidriver4x4]

Would be very interested in your take on the possible effects of the digging around in the red Forrest in Chernobyl. Things like Kicking up radioactive dust into the air and how it can travel with the wind is an interesting topic.

[@zapfanzapfan]

And what it would do to you eating rations covered in a bit of that dust.

[@saxon215]

I'm really glad you mentioned Charles Sheffield, this was a great read as a teen

[@scottmanley]

Wish I'd remembered his name.

[@80b]

With an ion engine, aren’t you also adding energy to the spacecraft that wasn’t part of the original mass, e.g. photos hitting the solar cells converted to electrons that add energy to the fuel?

[@scottmanley]

That too!

[@nathanmorgan9807]

With ion engines the gain in velocity has almost no effect on the mass of the projectile but let's assume for a minute we were using solid rocket motors. The energy released by the impact is a result of MV^2 so as long as the velocity gained is equal to or higher than the proportional loss of mass you will always be adding to the energy of the impact. A change in velocity has double the effect as an equal change in mass.

[@imconsequetau5275]

Solar cells do not convert photons to electrons.

[@nyxaerospace4319]

8:00, you can hear antare’s turbo pumps when you hear it in person, it’s a beautiful sound

[@Oddman1980]

15:08 I LOVE it when the author of a sci-fi novel puts an appendix in with all the math they used in the book! One of my favorites is "The World Is Round" by Tony Rothman about a very large planet that has an axial tilt like earth, but spins very slowly. There was an entire thing in the appendix with graphs and formulae just explaining how the seasons worked.

[@andrewharrison8436]

7:49 what an excellent question - fabulous that (once you are aware) you can pick out that sound in all those recordings.

[@KamikazeWombat]

That sound is the turbopump? I've always wondered what that crazy sound was!

[@crashmaster26]

Your video's NEVER cease to entertain and intellectually stimulate. I found you because of your legendary video on the Fountain wars in Eve Online. You are AMAZING!!!

[@UncleManuel]

"Thank you for thanking me!" 😂😂 I'm actually always impressed by Scott pulling factoids off his head and describing them in an understandable fashion. That's simply impressive! 👍👍

[@Arational]

Scott, audio book format is the best way to keep up with reading while you are doing mundane tasks.

[@acefox1]

14:00 Regarding guidance system updates on Apollo, if I recall correctly Mission Control determined that the doppler shift information on the radio transmissions was such a good reference that they used that as a primary source for velocity information to update the guidance system as well.

[@joevignolor4u949]

That's correct. After Apollo 11 landed about four miles from the intended landing spot they realized that velocity errors were at least part of the reason. Someone came up with the idea to use doppler shifts to get an accurate velocity measurement as the LM reappeared from the back side of the moon. This was quickly used to calculate a new false landing location to fool the LM's guidance system to land in the intended spot. If you listen to the later descents you can hear mission control reading up the new landing location and the astronauts punching it in. This was necessary on Apollo 12 because they wanted to land within walking distance of Surveyor 3.

[@wdavidwoods]

The Apollo missions used a blend of 2-way Doppler (for radial velocity), delay measurement with a pseudorandom number coded into the radio signal (for distance) and antenna pointing angle. This was, as you say, the primary means of determining the spacecraft's state vector (its position and velocity). The crews used star/horizon angle measurements to achieve the same thing as a backup. In the event, the command module pilots proved to be as accurate as the ground engineers in determining the state vector.

[@acefox1]

@@wdavidwoods awesome explanation! Thank you! 👏👏👏👏👏

[@tossedsaladandscrambledegg8576]

Really enjoy these types of videos. Both hearing the varied questions but also your thoughts and solo deliberations on the many what ifs. Thanks and keep flying.

[@KarlenBell]

9:10 I like how the rocket he's describing is right behind him, but he still uses his hands to describe the situation 😂

[@u1zha]

Hehe that too. I had the same reaction at 10:42 when he talks about a big payload bay and even turns his head a bit so his nose points to Shuttle payload bay and Hubble

[@noahway13]

Fake room, he's in a hologram.

[@senioravocado1864]

lmao, now that someone pointed it out its hilarious

[@128Cores]

@@noahway13 no, he himself is the hologram not the room.

[@sstroh08]

No that's actually a model of the rocket. The real thing is much larger. You're welcome for the clarification 😂

[@SRFriso94]

On hearing the turbopumps spooling up: one of the cleanest I can think of is the Raptor engine test firings. Because it's in HD with a good mic next to it, and there are two pre-burners spooling up instead of one, it's actually pretty audible. Obviously only for a second, because then it's overtaken by the Raptor itself, but it is there.

[@richardmillhousenixon]

I think what the first question was trying to ask is if, let's say there is a situation where a spacecraft with a base mass of 1000kg, with 500kg of that being propellant, and a velocity of X is on a collision course with an asteroid, will it be better to accelerate the spacecraft towards the asteroid, burning off Y amount of fuel (and therefore losing mass) but gaining Z amount of velocity, or will it be better to not burn, and impact at that base velocity of X but retaining all the mass of the 500kg of propellent.

[@BuffMyRadius]

Because kinetic energy is m*v^2 I would assume it's always better to trade mass for velocity, but someone with more knowledge would have to confirm that for me.

[@lunaticbz3594]

The answer would depend on the speed your already going. At slower speeds its going to be better to burn the propellent, but at some speed it would no longer be worth it.

[@BuffMyRadius]

@@lunaticbz3594 I think the opposite would be true. By the Oberth Effect rocket engines add mechanical energy more efficiently at higher speeds.

[@lunaticbz3594]

@@BuffMyRadius I just looked at an extremely slow, and an extremely fast scenario. 1,000 kg at say 10m/s is way less then 500 kg at however fast that propellent gets it moving. At 20km/s burning 500kg of propellent isn't going to give you more energy then having 1000kg travelling at 20 km/s. To actually figure out where it stops making sense to use propellent would require math, and exactly what king of propulsion and efficiency etc. But just looking at the extremes shows that at some point it stops making sense to use the engines.

[@mskellyrlv]

The Saturn V did I/II staging by carrying the interstage skirt with the upper stage until the ullage rockets had allowed the upper stage stack to achieve a safe separation from Stage I. Only then were the five J-2 engines started, and the interstage skirt was dropped as quickly as possible. If the skirt had stayed with Stage I, the outboard J-2s on the second stage would have to have been pulled out of that skirt, a distance of several feet. There was still a substantial dynamic pressure at I/II staging, which could cause either the spent Stage I or the upper stages to rotate and/or translate with respect to each other. The risk of a collision of the outboard J-2s with a skirt attached to Stage I was substantial. Moreover, the separation/ullage rockets on Stage II were solids, having no thrust vector control, and had their own motor-to-motor thrust variability - up to and including the failure of one or more to ignite. The chances for damaging the Stage II J-2 engines were just too great, so they carried the skirt with Stage II, and didn't ignite the Stage II engines until the stages were separated by a good distance (Stage I even had solid propellant retro rockets on it to slow it down, overcoming the F-1 shutdown transients). Once the J-2s were lit, the skirt could safely be jettisoned (it rode off on rails which prevented it from rotating and hitting the engines). The number of factors involved in tandem rocket staging is large, and the problem can be very complex. I was deeply involved in the development of the Peacekeeper (MX) and Small Intercontinental Ballistic Missile staging problems, and gained a substantial appreciation for the ins and outs.

[@pqddachu]

Well I think it's because saturn already has a few more rings to spare

[@Alexander_Sannikov]

fun fact about electromechanical indicators on aircrafts. one might think that they're just simple voltmeter-like devices, basically just a springed coil and a permanent magnet. well turns out they're way more complicated to make their readings stable in a tumbling aircraft. in fact, all those "voltmeters" have static coil interacting with a dynamic coil on the pointer and together they form a variable transformer that's used for feedback to stabilize the pointer even in a vibrating/tumbling aircraft. this is also why all those dials have that characteristic smooth type of movement as if they're submerged into a thick liquid.

[@Froblyx]

How about putting a great big spring on the front of the spacecraft approaching the asteroid, so that we get an elastic collision rather than an inelastic collision -- doubling the momentum transfer?

[@faroncobb6040]

I don't think you quite understand how fast something like the DART spacecraft is moving. It would be like putting a spring on the front of a bullet to make the bullet bounce off when it hit someone, only moreso.

[@Froblyx]

@@faroncobb6040 I should have added the appropriate smiley (🤪) to indicate that I was being facetious. The idea is conceptually sound, but the energy absorption required of the springy thing would be, well, far beyond anything we can build.

[@davidvomlehn4495]

Regarding IMU recalibration: attitude, i.e. the direction in which you are pointing, can be automatically recalibrated using star trackers and sun sensors, which provide very accurate information. Location is recalibrated using a transponder that sends a signal when it detects a signal from ground radar. The ground radar can then use the transponder's signal to locate the spacecraft. We use a transponder instead of trying to detect an echo of the ground radar signal because the strength of the reflected signal is proportional to 1/r^4, that is, it fades*really* quickly as you get farther away.

[@juzoli]

The biggest issue with the space elevator is not physical or technical. The problem is that it is a huge point of failure. If it snaps, then the whole structure is gone. And as long as terrorism and wars exist (= forever), it will never be safe.

[@HalNordmann]

No real space elevator concept is wrecked by a cable snapping. All of them have redundant cables, so you can do repairs if one of them snaps for some reason.

[@u1zha]

Good point. Though if one can build a space elevator, one can also build a few tethers for redundancy maybe...

[@HalNordmann]

@@u1zha Skyhook tethers are still useful for other reasons, like carrying things that need to be in Earth orbits that are difficult to reach from GEO.

[@juzoli]

@@HalNordmann We are not talking about predictable accidents here, but major catastrophes, and deliberate attacks.

[@HalNordmann]

@@juzoli Again - big redundancy and failsafes. Like ensuring the cable burns up in the atmosphere while falling.

[@Cirrus4000]

I have that Haynes manual and read it a couple of years ago. It's one of the best books on the Saturn V I've read. Not too technical but still has plenty of details and some amazing pictures.

[@AsbestosMuffins]

"You don't want 100 questions in a single video? do you??" Drachinifel does several hour long Q&A's every week, I don't know how he has the time but its a meme on his channel that a 2 hour AMA is light on content. Mind you, he's researching most of the questions too.

[@Gapsx1eGewehr]

Ah yes, a fellow Drachinifel fan. _tips stalhelm_

[@AluminumOxide]

8:21 the space shuttle main engines also make a whistle sound before igniting

[@robbhahn8897]

Yes, it's an amazing sound. I was at the Atlantis launch in 2010 - third to last STS launch ever - and was quite surprised by the sound, even from 3 miles away.

[@RudolfGraspointner]

Question: The ISS and Tiangong space station obviously have different orbits. But, how close to they eventually pass each other and how often. Can someone do a simulation showing this? .... Space elevator: a high chance of satellite collision!

[@sirnik84]

I saw Red Star in Orbit meany years ago. Made me a fan of Alexi Leonov. This year for my birthday I bought myself a lithograph of his painting First Walk. Its hanging next to my lithograph of Alan Bean's painting First Men: Edwin E. "Buzz" Aldrin

[@Rarius]

You don't want a hundred questions in a video, do you? YES WE DO!

[@mistergiea9758]

one day my friend, one day!

[@wmarkwitherspoon]

My late FIL worked on the rover and the lower LEM stage. He developed using the screen wire/plates for the "tires" as well as the folding problem on getting it compact. Lots of compressed springs to get it to unfold in the right order.

[@hillogical]

You don't want 100 questions in a single video, do you? *Drachinifel has left the chat*

[@witeshade]

Once a month 5-6 hour video for patreon questions. Masochistic for him perhaps but pretty damn awesome for his fans!

[@allangibson2408]

The later generations of LM also had a higher specific thrust engine thanks to a larger and longer descent stage engine bell. The extended bell was actually destroyed by impact with the lunar surface on Apollo 15 because they were so much longer. Apollo 15 was the first with a rover.

[@SOU6900]

Something I just thought about last night is how does Russia expect to separate from the ISS when Zarya, if I remember correctly, is actually a US owned module even though it was launched and controlled by Russia? Wouldn't that just make things worse for them considering they're loaded with sanctions and such at this point?

[@fridaycaliforniaa236]

I see this more like they would just abandon it and make a common project with China, but this is pure speculation. I have Russian origins. Russians don't like to lose time with complicated things, so I guess they would just shut it off and let it become an inert cold fridge still tied to the ISS ^^.

[@bee5440]

They're not going to separate, Rogozin is just doing this for political reasons

[@jess2690]

Really enjoy knowing everytime I click on one of Scott Manleys videos, im going to come away with more knowledge on a topic I love so much. Thank ya for all the work you do!

[@gregalbert4033]

👍 love your work Scott! On nanotube "ladders/elevators"... Those, for purest strength are carbon, correct? There is I'm sure massive amounts of math devoted to the logistics of this. But for ONE thing, which is never, ever discussed.... Electrical charge. INCOMPREHENSIBLE electrical charge. If it didn't vaporize basically right on the spot, it would probably be capable of having at least half of the current instantaneous load produced on the Earth at that moment. It's PURE CARBON NANOTUBES!!! How much electrical potential is just in the lower atmosphere on a beautiful day? Alot... And take it to the outer atmosphere and Van Allen Belts?? Largest van deGraff generator ever, not to mention lightning bolt as it vaporizes... Just sayin....

[@stuart207]

Interesting point I've never heard mentioned... 👍

[@surferdude4487]

Besides being a space elevator, it would be a massive power generator.

[@johndododoe1411]

van Allen belts won't make it act like a friction van deGraff generator, just as a lightning rod for the charge provided by the solar wind hitting our magnetic shield. However inserting isolator sections at regular intervals could disconnect the lightning effect, or an internal metal cable could act as a lightning rod. Anyway, Clarke's book used the kind of carbon fiber material now routinely used by the space industry, not the currently hard to obtain nanotubes. There were some openly admitted unrealistic elements for fantasy reasons.

[@gregalbert4033]

@@johndododoe1411 would think the additional weight to neutralize it from electrical charge would be prohibitive. The generator analogy is somewhat poor, I know, but the idea is the same here. And if you think Auroras aren't electrically charged as hell, we need to talk. Same charges exist above the equator, just WAAAYY higher up...

[@gregalbert4033]

@@stuart207 Thank you...I have always wondered why that is. When I first heard of the concept when I was a kid in the 70's, that's the first thing that popped into my head for some reason.

[@ut4321]

Excellent Q&A! I learned some unique, new facts today. Thank you Scott!

[@saicharangottipalli4200]

I have just watched First Man and found your video here. That's Amazing

[@manic6030]

You can clearly hear the turbopumps in the video "The Ultimate Saturn V Launch Video with INCREDIBLE SOUND!!!" and it's glorious!

[@meh4841]

I have that Saturn V manual!!! a friend got it for me for Christmas one year

[@mytech6779]

Ring laser gyros have been used in large aircraft inertial reference systems since the early 1980s. They only have a tiny amount of drift and are sensitive enough to get the aircraft's latitude during the warm up initialization by sensing the earth's rotation. But they are still cross checked and adjusted in flight by the flight management computer using other external data like ground beacons and GPS.

[@mr88cet]

To *deflect* an astroid you want to transfer momentum to it. To *destroy* an asteroid, you want to transfer kinetic energy to it. Momentum is proportional to velocity, whereas Kinetic energy is proportional to the *square* of the velocity.

[@MadMan020998]

Yes Scott! We do! Bring on the 100 Question live stream!

[@rajinkajin7293]

Scott are you insane please once a month release a straight download of like 100 questions, an hour long, podcast friendly, pinnacle of content, the likes of which remain unseen since the days of hello Internet!!!!! Love you Scott, fly safe brother

[@Vatharian]

One very commonly overlooked part of building space elevator is that it requires mopping up and leaving empty orbit. It's either/or situation - either you have SE, or free orbiting satellites. It is possible to plot high inclination or polar orbits that would consistently avoid the elevator location, but anything close to equator is a hard no, and even then, any case of high angle collision )like Iridium and Roskosmos) puts the elevator at risk. This means all LEO infrastructure would need to go - from communication satellites to imaging systems, and all would remain is geostationary with it's 220 ms ping.

[@HalNordmann]

You just need a slight inclination to avoid the elevators.

[@darkonc2]

I think that a wonderful example to explain the DART question is that a doughnut contains about the same chemical energy as a similar mass of TNT -- but because the energy is expended much slower, it won't blow up your car on the way home (unless you have *serious* digestive problems).

[@wings9925]

Love the Haynes Saturn V manual. One of my favourite books on its construction

[@whirlwind201]

David Woods got this exactly right. When the first and second stages separated, no engines were thrusting, and the computer had essentially no directional control over the two stages. If the skirt had been attached to the first stage, there was too great a chance that the skirt would contact the second stage engine bells and damage them. During the 30 seconds between first/second stage separation and skirt separation, the computer's singular focus was to ensure that the vehicle was traveling absolutely straight -- never mind if it was following the desired trajectory -- so that when the skirt separated, it would slide smoothly backward. Once the skirt separated, the computer resumed actively guiding the vehicle on its planned trajectory.

[@OregonOrcadian]

Scot, thanks. Your space knowledge is so awesome.

[@DUKE_of_RAMBLE]

"Co-elliptic Phasing Maneuver" would be a *_great_* future Space Metal band name! 🤘😬🤘

[@JHuffPhoto]

Love that you have a bottle of Buffalo Trace White Dog on the table behind you. I live near where they make that stuff. It is not my cup of tea but it has sometimes been referred to as "rocket fuel" so it is appropriate.

[@patricbernardo1807]

It is what I imagine corn based rocket fuel to taste like.

[@CountArtha]

I've done that interstage/ullage thing in KSP with structural rings and Separatrons. It's good for rockets whose first stage doesn't _quite_ have enough kick to get it past 18 km and staging would send it tumbling in the atmosphere. The push from the Separatrons stabilizes the back end while you start the second stage engine and raises your apoapsis to make its job easier.

[@themellonfactory]

Red Star in Orbit originated in a book of the same title by James E Oberg, which is superb.

[@dsdy1205]

For question 1, I like how the questioner basically chanced upon the physical explanation for how the Oberth effect. In short, yes, above 3 km/s or so the fuel does carry more kinetic energy than is stored as potential energy in its chemistry.

[@JesterSpeight]

Hey, Scott! Check out your Cirrus POH. You should see that it's actually using a pair of magnetometers in the wingtip for your HSI, not GPS. Pito-Static gives you your up/down and relative wind speed to the aircraft. The avionics pairs pito-static and OAT sensors to give you True Airspeed, and your GPS will give you ground speed and track.

[@steviepatterson7285]

I would definitely recommend the Haynes Manuals for space and rockets I have about 5 and if I every have a question I can just look in them to find a answer

[@torelie6581]

Yes, come back sooner than that👍 Wish you all the best on getting your flying license (fly safe😉). Yes I see you have limited of spare time. At the same time, you are doing some nice things with your time. Keep it up Scott, allways a pleasure.

[@chrisblake4198]

Another interesting thing about air inside the rocket on launch- I learned from Smarter Every Day that the JWS shields had micro pinholes so when in its folded launch configuration, air would escape evenly as it expanded during launch. The holes in each layer were specifically plotted out so when unfolded the holes in no two layers lined up, thus maintaining protection.

[@DonNelsoni]

Yes, we would make you do that. Bring on the 100!

[@stevejordan7275]

Yeeow, that spinup on the Gemini (8:27) was fantastic. Knowing what I was hearing was even better; using a solid rocket motor as a pump starter? That's so nuts and cool at the same time. Okay, yes, it gave me a wave of goosebumps. So I'm a nerd.

[@stevenwilliams1805]

This was an enjoyable break for the typical format.

[@paulcadden4967]

Question, we all know the super Draco engine was made for propulsive landing but is now just used for launch abort. So, 1) why are they still built in when you could save the weight in the capsule and just have a system in the trunk? 2) As they are still there, in the event of a catastrophic failure in the parachute system, could it still be used to save the crew as originally designed?

[@rty1955]

Hey Scott love your channel. Just some fun facts during the first Apollo moon mission. I grew up in Bethpage, Long Island about 1/4 mile from the south approach end of the runway. As you are aware, Bethpage is where the LEM was built by Grumman. Almost everyone that loved in Bethpage worked @ Grumman on either the Navy projects (E2C, F14 etc) or the LEM project. The plant was 24/7 operation to meet the goal. My best friends father was in charge of the wiring for the LEM. One day, I was outside in my backyard when I heard some very unusual engine noise approaching. Being that close to the approach end of the runway, I could actually wave to the pilots that flew over my backyard. But this engine noise was something I never heard before though. When I looked up I saw the NASA Guppy coming in for a landing! It looked like a blimp with wings! It was HUGE! The guppy was there to pick up the LEM and fly it to Florida. I think the departing flight was at night under the secrecy of darkness. Did you know they made two identical LEMS? One went to the moon, the other remained in the hanger @ Grumman in Bethpage where all the engineers were. People actually slept at the plant when the astronauts were on the moon. They were there in case ANYTHING was needed by the engineering team. Very nerve-wracking!. My friends father said they were most nervous when the LEM was to depart the moons surface as once the engines ignited, they could not be shut down! There were wires that connected the accent stage to the decent stage and were cut with a guillotine as soon as the accent Engine was ignited. That is that small explosion you see on the video as the guillotine was activated. If the wires failed to sever the accent stage would have never made it off the surface! After the astronauts were safely home, the second LEM was pushed out into the parking lot and spray painted camo green! I used to see it in the parking lot everyday on my way to/from work and just thought: all that engineering, just being destroyed in the rain. How sad. I thought they could have sent it to the Smithsonian, but I assume it would have been cost prohibitive to transport it. Sadly the Grumman plant in Bethpage closed and the land was sold to developers. Closing Grumman was a very sad day for the proud residents of Bethpage

[@davidlabedz2046]

Always enjoy the Q/A videos!

[@caldodge]

One thing that's rarely mentioned about space elevators is the need to remove ALL orbital items below and above the geostationary point. Every item that orbits crosses the equator at least twice per orbit, so eventually such bits would hit the elevator. IIRC Clarke addressed this with some way to bend the cable out of the way, but that seems impractical with so many satellites, etc. flying by.

[@simongeard4824]

That Haynes manual for the Saturn V is awesome... I don't own a copy, but I found it in the local library a while back. Lots of interesting stuff about the history and development of the vehicle...

[@poiu477]

I would appreciate longer form ones or more frequent updates, but only if its possible with your schedule Scott. I wouldn't want you to sacrifice anything you personally enjoy just to "catch up" with the questions, but if it were in the cards I'm a guaranteed watch!

[@sonnyburnett8725]

I can’t believe they had “Sound” as well as video on the Delta Heavy. Very cool.

[@truman42746]

I have a complaint! Your videos are just not long enough! I love it when people ask questions about the Saturn V rocket. People don't understand how complicated it was getting us to the moon. Everybody should make an effort to see one of the remaining Saturn IV's in person. I have seen two and it's truly amazing what we did with slide-rules over 50 years ago!

[@truman42746]

@Aaron Thanks for the correction.

[@MrRolotube]

I think the reason for keeping the S-I-C/S-II interstage connected to the second stage for a few seconds was not so much the ullage motors, but it was considered to be safer than detaching it together with the first stage, because there was a risk the interstage might touch and damage the second stage J-2 engines.

[@frankgulla2335]

Great Q&A, Scott. You do a great job informing us. And for us "Amerikins" your Scottish accent is icing on the cake.

[@w5cdt]

Hey glad to know you are flying a Cirrus! I'm a G2 SR20 driver....about 1100 hours in type.

[@mikerichards6065]

The Chertov books are fantastic - and even better being a free download. I would also recommend: 'Challenge to Apollo: The Soviet Union and the Space Race 1945 - 1974' by Asif A Siddiqi at the NASA History Office. It's not first-hand, but Siddiqi got incredible access to the Soviet archives and goes into a lot of detail which might be just what you need.

[@tracyrreed]

Hi Scott, For the sake of simplicity at 13:25 I would simply refer to this as a directional gyro or gyro compass instead of as an HSI. The VOR component of the HSI is unnecessary to your example and it's the directional gyro which gets aligned to the magnetic compass. It almost looks like the instrument in the pic is a standard directional gyro and not an HSI but I think I see the little OFF/NAV flag showing in it so perhaps it is an HSI. I almost envy you because my private pilot days were a good time and a lot of fun. Now I'm thousands of flight hours later flying professionally and look back on those days fondly. Have fun and thanks for the great videos!

[@chdarwin05]

I always learn something new and exciting here. Thank you! Best wishes with pilot’s license.

[@donraptor6156]

My Dad worked on rolling the rings for the Saturn 5. Long Ago...

[@Dude3210123456]

More than 100 questions per video would be very desirable and a mark of flying safe!

[@LuciFeric137]

Material for the space elevator: scrith. Nucleosynthesis is still ongoing. Stars are atomic and quarkonium factories. We haven't found ccx everything yet.

[@williamblack4006]

@Luci Feric -- Scrith! Larry Niven rules.

[@dmytropetukhov325]

JWST has some features that may enable certain service missions: a refillable gas tank, removable heat protectors, visual guidance targets, and accessible attachment points. The biggest problem with servicing it is that crewed missions to L2 are currently out of the question, and automated servicing is limited (and was even more limited when the design plans were finalized).

[@ryanhamstra49]

Now we need a 4 hour video catching up on all the questions!

[@iratozer9622]

I am LIKING, SUBSCRIBING, and ringing the BELL, because you did not ask me right up front. By the way, very informative and funny. Thank you.