How The Space Shuttle Started Its Engines And Launched 

These launch videos are such eyes candies. It’s interesting to see all those exhaust plume and smoke travelling in slow motion - to see it travels in orderly way as opposed to the powerful chaotic turbulence we would see in the real time footages.

That shot of the engine bell wiggling back and forth between oval shape and round at 6:55 always amazed me; the pure power and fury of what was happening to that big piece of metal was astonishing. Watching live shuttle launches was a thrill that never got old. The engine startup was like a shot of adrenaline.

11 minutes to explain 10 seconds. This is quality content. Also, Space Shuttle is still the coolest spacecraft ever.

Great explanation of the startup process, Scott. I was the Quality Assurance Manager for the Solid Rocket Boosters and External Tank processing as well as processing of the entire vehicle once rolled out to the Pad. I started as an inspector working on all those systems with operations and engineering. I spent 29 years out there and loved every minute of it. Keep up the great work!

The fact that only ten seconds of launch it-self can be expanded in information packed eleven minutes and STILL be highly simplified, is testament of complexity of this whole situation :D

I always liked the description of the SRBs as "when those ignited, the question wasn't whether you were going to space, but how much of Florida you were taking with you"

The first SSME live firing I saw was on my first day working for Rocketdyne at Stennis. I remember being in awe of the power as I watched the test from only 1/4 mile away. I witnessed (and eventually ran) a lot of SSME tests in the years following that day. By far the most fun I've had in my 25 year career.

The engines are splayed into the "start" position not only to prevent the engine bells from colliding, but also as a thrust alleviation as the twang loads are applied to the stack. Engine 2 and 3 are gimballed away from each other in the start position, then move together for the liftoff position. If the engines started in their liftoff position, yes the engine bells would be in more danger of collision during startup, while at the same time increasing the twang loads applied to the stack during startup prior to launch. We have to remember that all these off center thrust loads are translated via the SRB field joints. SLS will not have to deal with these "twang" loads that STS did. A few days before launch, the SLS stack will be unbolted from the Mobile Launcher. Since there are no twang loads from the SLS stack, no T minus Zero pyros are need to release the stack from the ML/MLP. In STS days there were 4 frangible nuts that held each SRB to the ML/MLP(Mobile Launcher Apollo and Space Launch System/Mobile Launcher Platform=Shuttle=Space Transportation system. These nuts were detonated via 2 redundant NSD's(NASA Standard Detonators) per nut, 4 nuts per SRB 8 nuts per stack. These charges were initiated along with the SRB T minus Zero signals which lit the starting charges at the top of each SRB. These charges cause a flame front along the entire inner surface of the SRB propellant face. Varying the exact inner shape of the solid propellant allows a certain amount of "throttling" to occur. When the 3 Space Shuttle Main Engines which supply just 1.2 million pounds of thrust at liftoff while the 2 SRBs provide 6.4 million pounds of thrust at liftoff throttle down from just over 6 million pounds thrust down to 4.4 million pounds thrust just before entering the area of maximum dynamic pressure(MAXQ), the SSMEs reduce from 104.5% rated power level down to 67-72%RPL, while at the same time the SRBs thrust decreases thus allowing the Shuttle stack to not crush itself like an aluminum can as it accelerates into the supersonic regime of flight. Following MaxQ, the 3 SSMEs go throttle back up to 104.5% and the SRBs thrust increases up to 5 million pounds thrust. The RSRMV(Redesigned Solid Rocket Motor V=five for 5 segment motor) will have 4 RS25 engines that have actually flown on many Shuttle missions already. The quartet will thrust at 109% RPL, while the new 5 segment RSRMV's will thrust with approx. 4 million x 2 pounds force thrust off the pad. While there have been 5-6 tests of a 5 segment RSRM or FSB Five Segment Booster, they have all been horizontal and have never been fired in the vertical launch position.

Thanks! This was great!

Hi Scott--Very nicely done. I'd like to add a few things that I hope you might find helpful--Regarding the preburner oxidizer valve opening profiles (OPOV and FPOV) the 'dipsy-doodle' nature of these is because of the nature of the initial hydrogen flow into the preburners (especially the Fuel Preburner). When the Start begins, the Main Fuel Valve is ramped open at (essentially) max rate. This causes the downstream fuel lines (the 'steer horns' on the nozzle extension) as well as the nozzle tubes to be 'filled' with hydrogen. The nozzle extension is made from 1080 stainless steel tubes of about 1/4 inch basic diameter each. A VERY high quality heat exchanger! For the next 2 - 2.5 seconds, the fuel system feeding the preburners 'chugs' at its first natural frequency (about 2 Hertz) as that system tries to achieve thermal equilibrium. The hydrogen supply pressure to the preburners oscillates during this period at something like 80 psi 'peak-to-peak'. The 2 high pressure turbines have very strict temperature limits, therefore the mixture ratio going into each preburner has to be 'controlled' (quotes because it isn't really 'controlled'--all of this stuff is open-loop) to keep temperatures from getting out of hand. The opening profile on the FPOV (especially) does what it does to attempt to keep the incoming LOX flow 'in sync' with the oscillating fuel flow. We should make note that it doesn't always work--the start of an SSME is not 'deterministic' as such. We still get temperature spikes in the fuel preburner--we've had some as high as 4000 deg R. Some occur in the Oxidizer Preburner also--STS-68 was an example of such. It takes about 2-and-a-half seconds for this situation to sort itself out. Also note that in some cases (around 5% of the time) the oscillating fuel pressure just doesn't happen--no one knows why. The preburner valve profiles then had to be modified again so that the engine would start acceptably well in either case. Note that the Fuel Preburner is intended to 'start' at Start Command + 1.4 seconds. The Main Combustion Chamber is intended to 'start' at Start Command + 1.5 seconds. This brings up fuel pump turbine 'back pressure' and prevents overspeed. The Oxidizer Preburner is intended to 'start' at Start Command + 1.6 seconds, although that is not as critical as the relation of Fuel Preburner-to-Main Chamber 'start'. This sequencing changed a bit with incorporation of the Pratt & Whitney turbopumps, but for the configuration of the engine you show, and the start sequence plot you show, those are the numbers. Thank you very much.

Scott, you have simply outdone yourself with this one. I have watched this astounding sequence at least a dozen times in complete awe that such a document can even exist, never mind be of impeccable photographic quality. No living thing could survive a millisecond of the conditions extant at any point past ignition, yet our eyes are present, focused, and aperture-adapted to perfection in multiple locations for the entire process. As the hold-down bolts’ charges explode and 6 million pounds literally leaps off the stand with flawless alignment, I am reminded that essentially, I am witnessing the impossible.

This video answered a ton of questions I have always had regarding different aspects of a launch. Thank You.

And those beautiful RS-25s will now be on a one way trip to the bottom of the Atlantic. Hopefully they get the coverage they deserve with 4K video during the launch and start up.

Explaining the white pressure threshold with the ambient air was outstanding. It's comforting to know that there are people out there that actually understand these things and can explain them so clearly for the rest of us. Thanks Scott!

Dont get me wrong, the things we are doing right now with space travel is insane. Rockets that can land themselves, going back to the moon, and going to mars here in a "few" years.... but my god look at that footage. Nothing beats a launch of a space shuttle. Just pure beautiful power and engineering. And they made all that with minimal computer help compared to todays tech.

"In technical terms they call this... 'twang'" Love that!!

About the covers over the thrusters, neat story- they originally wanted to use Teflon plugs to cover them in order to prevent rainwater accumulation that could freeze during ascent. They decided to use butcher paper instead since it was lightweight, commercially available (ask your local butcher!), it would easily dislodge during the first thruster firing, and above all, it stopped water from entering the thruster nozzles. After STS-107 they switched to Tyvek covers, since I guess they were finding chunks of paper in the window seals (which probably gave the engineers nightmares!). The newer nose thruster seals had parachutes which caused them to detach in a more predictable manner during ascent (usually as the Shuttle cleared the tower). (Watching those bursting thruster covers during this video also gives me a clear indication of what would happen to your eardrums if you were there during SSME ignition...). Thanks for posting this video, Scott!

I always loved watching it launch. It looked so powerful. Especially in slow motion. And the sounds!! Never been to a launch but there are a few great videos with awesome sounds here on RU-vid.

I always love to watch a Shuttle launch sequence, especially starting at T-9:00. The call at T-0:31 go for auto sequence start still puts shivers down my spine.

This is the reason why YT is my only social media addiction.

I can watch Shuttle launches all day. Even though I have seen these clips countless times, it's always a treat with Scott commenting about all the bits n bobs. Fortunate were those who got to experience Shuttle launches first hand.

I'm 70 years old and had just graduated from HS when we first landed on the moon. The Space Shuttle program that followed was a fascinating extension of our space-going program. This video answers some questions I had about the Shuttle launch technology. In particular, the ROFIs. I had assumed all these years that they were what actually ignited the Shuttle engines on launch. Interesting to learn they actually combusted stray hydrogen molecules for safety reasons. Never too old to learn (and appreciate), I guess.

And now imagine all the flat earthers who think NASA went to all this effort just to pretend that the earth is round....

In 3rd grade we had someone come to our school to talk about the space shuttle and they brought one of the tie down bolts, it was hefty, took both hands to lift it.

I remember the night launches as otherworldly events. Simply fascinating that so much power could be controlled in such an elegant way.

A friend's father was a turbopump specialist at Rocketdyne. I really enjoyed talking with Lou over a cup of coffee. The shaft seals on the RS25 turbopumps were a bizarre design. As I understand, the shaft had multiple stair steps, but no mechanical seal. As gas flowed past each step, a vortex resulted. Apparently they leaked like all hell until all the vortices were established, then the magic sealing happened. When the designer proposed the design, many thought that he was daft. He was later regarded as genius.

So much of rocket engine design is "we changed things until they stopped destroying themselves."

That is SO cool.. I've seen snippets of this footage for many years.. but to have your expert analysis commentary over the top makes it all the more awesome.. :) Thanks Scott 👍

The sound of the space shuttle starting is amazing, and those blue cones forming in the exhaust seem almost magical.

Well done Scott. I do wish that SpaceX and NASA would use photochemical high speed cameras on their future launches, but I doubt that will ever happen.

In another video about the Shuttle launch, the narrator said at some point, that the Shuttle computer, when ready, would in effect tell the launch system to "let me go." For some reason, I always cried at that. Making the Shuttle most human at that moment. Let me go indeed.

I've reached the point in life where things I watched live are now historical.

Serves as a good reminder to load up my ISO of the "Ascent: Tribute to Shuttle" DVD and rewatch this plus "Riding the Booster" once again. The film footage is incredible quality, thanks for sharing it Scott.

There's not much that's more of a beautiful sight than seeing the SSME fire and come up to full power. The shock coming off as it builds power is amazing in my eye

I have watched the original video so many times and my absolutely favourite part is watching the engine bells flexing during startup, so mesmerizing and powerful. I loved the side-by with the graph showing the startup sequence, very interesting!

- Captain? The bolts are still keeping the nozzle. - Put this gas pedal a little more to the metal but not much. - We ripped some hardened steel, sir. - Good. Jane, take us off, please. - Yes, sir.

“Rocket porn” indeed: another excellent video, Scott. Helps us amateur newbies appreciate the complexity of “stage zero” & what SpaceX are trying to build in record time at Boca Chica. Hold-down clamps, quick disconnect arms, wobbly closed-loop control of engine start-up sequences. They may have mastered these things with Falcon, but as this video shows, they’ve had to start all over again with this stuff for Starship, and at a whole other level…

I like how rather than "FIRST" comments we get "Hullo!" comments

1:23 little did we know it would launch on November 16 2022

The breakdown was super. The ingenuity of the people who designed the rockets is just another level

I don't know how many times I've watched that launch video, but it gives me goosebumps every time. I wish spaceX could do this for their launches.

Damn I miss the shuttle! It was such an incredible vehicle and spectacular to watch. I grew up I central Florida and never tired of watching the launches. Within 10 seconds after liftoff we could see the vehicle in the sky with the naked eye. We would watch the watch the countdown and launch to clearing the tower on TV and then race outside to watch the remainder.

Footage like this should always be shot on film. Preferably 60mm, 70mm or better. We should have be able to rescan down the road for future display resolutions.

this was amazing. its crazy to think shuttle had sometimes to use force to pop the bolts as backup plan

For all its flaws and shortcomings... what a majestic, beautiful and awestriking vehicle.

I love you Scott Manley. Planning to name my 1st born after you ... but he (now 19 yrs old) just nixed that idea. Seriously, great video as always. Perfect combo of scientific knowledge, research, humility & humor. Thanks!

We were lucky to have been on a tour in 1982 with a "vehicle ready to launch. We were told about the millions of gallons of water that was released after the motors started (don't see that in your video). A few day later we saw the launch - that sound is amazing and cannot be described. Absolutely amazing......

This guy is amazing... He can make techinical procedures about the shuttle program extremly understandable. I have never found better videos on the shuttle abort steps than his.

SSME's: "We can go from initial start-up to full thrust in under 10 seconds!" SRB's: "Hold my beer."

As a space nerd since the early sixties I watched launch after launch and marveled at the majesty and the incredible science. Hats off to you Scott for an highly skilled job of editing, composition and second by second narration. Wow!

It's worth noting the F1 turbine exhaust wasn't just dumped overboard uselessly -- it was injected into the nozzle extension and formed a layer to insulate the metal from the heat of the main combustion (in hires video of the Saturn V launches, this cooler exhaust "sleeve" is the dark area right after the nozzle) and also added (per a video with Luke Talley) about 18K lbs of thrust, small but not wasted.

Until a few days ago, I never knew about the hold-down bolts that held the SRB's in place. This was an awesome video.

Sometimes in hindsight it's hard to believe that we actually flew such a crazy design. Engineers can make almost anything work.

YES!!!! I love when Mr. Manley talks about the Space Shuttle. My cousin flew on the shuttle several times.

It's sooo much more interesting watching these videos now, than it was when I first started school as an aerospace engineer. Now that I'm in thermodynamics, and other core engineering courses, I see the images and hear you talking about the processes, only to further think about temperature-pressure-volume relationships, and entropic-enthalpic concepts within the systems that you discuss. thank you for the continued inspiration Mr. Manley, and as always, "Fly safe!"

I could listen to this dude all day.

This was a really exceptional video. Made me realize just how much I miss watching Shuttle launches. Thanks, Scott!

This may be your finest video. Simply amazing. I kept running the video back so I could see each detail that you pointed out. Can you do a video showing anomalous conditions that caused aborts in this style? Again, simply amazing... fantastic.

The engine nozzle wobble from the flow separation and its transition to the shock diamonds are some of my favorite imagery ever!

This is by far one one of my most favorite videos from you! Well done good sir! Every time you make a video on how different rocket engines work my mind keeps getting blown away realizing just how incredibly complex these engines are!

Yeeted to LEO! 🚀 The original videos referenced are totally worth a watch. I think I watch it 2-3 times a year.

I never thought much of the engine bells wobbling until I met one up close and felt just how solid they are. Let me tell you, it's not made of cardboard or cardboard derivatives.

As someone who breaths, this is truly breathtaking.

I honestly never realised how absolutely massive that rocket was. I’ve always seen the video and photos of the shuttle launching and taking off from far away, It’s almost like lifting a whole skyscraper off the ground into the sky.

I'd seen the running video commentary that the Shuttle engineers had made on the liftoff sequence but this video brings the description to a whole new level! Much appreciated!

I am in love with your channel! I loved watching those Space Shuttle launch videos earlier but never thought how interesting the startup of the behemoth could be!

I watched the original video awhile back. It's amazing how much happens in that first few seconds of the launch. The man who's explaining everything does it really well too.

Absolutely love this Scott. Somehow, the fact it's all shot on film and you can actually see the sprocket holes makes it even more special.

I never noticed the 2 spring-like devices on the outside of the hold-downs. Maybe just coils of wire or something. Forget onlyfans. These videos are top quality content. “Oh yeah, check out the lip of that flow separation.” True nerd pronz.

Not gonna lie, I usually get bored during these type of videos, but this was so interesting!!! Thank you!

This has got to be one of the best explanaitions of any subject on RU-vid. Everytime I wanted to ask a question it got answered in the next sentence. This is like Dennis Brain level talent.

I miss the Shuttle!

Yessss! Exciting to watch, can't wait for the launch of RocketHub 🚀

Even if you consider its failures this was amazing ship. Its so much easer to never have a failure with a capsule. A ship that returns from orbit and then does it again wow. If starship can pull this off and thats a big if. It will also be amazing

7:16 the forming of shock diamonds and the flow separation lines are just so beautiful, as if they're straight out of a sci-fi movie

When we casually use the expression “rocket science” to denote something complicated few understand just how complex rocket science (especially the engineering) really is. And your (excellent, as always) video is of just ten seconds’ worth of the mission - and just part of the launch mechanism!

One of your best Mr. Manley! Love seeing and understanding!!! ❤️🚀

Gasp! I think I was holding my breath for all 11:50! Beautiful footage splendidly presented. Greetings from Kent, Scott!

That final split second overhead shot of the 'detach & go' is super cool, especially after your detailed explanation of all the individual parts of the process.

Fantastic, I've always marveled at the lighting of those three engines. Your explanation was so detailed and informative and showed me how much I'd missed!

I think there's a good argument to be made that the twang motion, while a designed-in feature of the shuttle launch sequence (and a necessary consequence of using solid and liquid engines that can't be ignited simultaneously), was a critical mistake in the Shuttle's concept, having placed significant structural loads on the boosters and their section joints. Maybe not the most important cause of the Challenger's destruction, but possibly a significant contributor.

Man, this was the best dump I’ve taken in a WHILE

Damn, wanted to see 10 seconds of a Space Shuttle launch, and stayed 11 Minutes ;-)

An absolute "Stare at the screen I cannot avert my eyes" video ! What a great delivery of technical info that is easy to follow along.

For comparison's sake now, I really want to see what a Raptor Vacuum ignited at sea level looks like

Air & Space magazine did an article probably 15 years ago about all the fluid flow, pressure changes, valve synchronization and timing etc. believe they said something like if you could explain all the intricacies of what happened on ignition you would qualify for a PHD in that field. might have been in an article titled 8 minutes in hell or something like that.

THIS NEVER EVER GETS OLD!!!!! Well done much appreciated!

I can never get enough of these engineering videos of the Shuttle launches - and the Saturn Five launches were even better with their old grainy film. But the best were the Mercury launches in the early sixties; they didn't even have cameras. Instead, they had about 5 artists sitting around the launch pad, sketching their little guts out as fast as they could.

Maybe if I’ll be as smart as Scott, I’ll also have his wonderful haircut? 😂

Good thing those hold down bolts have "just enough" strength. Imagine the separation failing and everybody has to wait for a couple of minutes before the SRBs run out of propellant, as the shuttle struggles on the pad.

I love that shot at 3:05. It's never a good day when you have to walk to the bottom of the flame trench to retrieve your test engine.

This video never gets old for me and one of the most detailed yet simple to understand explanation of the ignition process of those RS-25 engines on RU-vid I have seen. Sorry its taken this long to comment.

The SLS is the culmination of technical genius that went into designing and perfecting the Space Shuttle and all its many complex supporting systems. It only took Boeing $23 billion and 10 years to restack it. With a total projected cost $27 billion through 2025, it is very impressive (sarcasm) that Boeing could do so little for so much and get away with it.

The cameras and their film are engineering marvels in themselves. To be able to cover such a wide range of exposure and produce such detailed images without noise at these incredible framerates is just mindblowing. Same goes for the original Saturn footage from the 60s and 70s.

scott this is my new favorite video on the internet, thank you so much for running through all that, you answered some questions i've had rolling around for a few years.

This is the Scott Manley-est Scott Manley video I've ever watched.

I didn't realize I was into rocket porn until now. It definitely puts a different spin on what's going on when someone explained it as it's happening.

hullo

1:30 I spat out my coffee

The Shuttle was a piece of complex machine. Kudos to the engineers who worked on it