Why Atlas Is Using Dual Engine Centaur For Starliner
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- Опубликовано: 3 сен 2018
- Boeing's Starliner crew vehicle will be the first payload to use the Dual Engine Second Stage on the Atlas V since 2004. While the 2 engine version offers better payload to orbit, it's very expensive and the actual reason for the 2 engine requirement is a bit more subtle and stems from earlier plans for post-Shuttle crew vehicles.
NASA Spaceflight Forums has a lot more on this subject, including links to many of the documents I'm citing
forum.nasaspaceflight.com/ind... 
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4 engine Centaur. That's KSP engineering right there: When in doubt, add engines.
The SLS upper stages - ICPS and EUS - are more like an inflated Delta Cryogenic Second Stage with more engines, than like a giant Centaur. But yes, that entire rocket is a bit Kerbal and not in the best way.
More engines, more struts. Quick mafs
Same with the SRBs. Need some extra delta-v in a hurry? Strap on a few more boom sticks.
Not as Kerbal as a Saturn V. Five F-1s on the first stage, Five J-2s on the second stage, and get ready for this.... a *third stage* with another J-2!!!!!1111!!!
Them $$$$ gonna fly...
How many times have each of us done that absurdly high angle burn with our underpowered upper stage just to keep from dipping back in the atmosphere while playing Kerbal? LOL
Shamefully I have. But Scott make a point, KSP needs g-force repercussions. Or an option for it at least (unless they add that within the last year, been on a hiatus
This was my standard launch profile! I don't know the exact stats, but in KSP nuclear engines are efficient enough that it's better to use a nuclear engine even if you have to pitch up 35 degrees.
There are mods for that.
@@ThomasKwa Living on the edge every time. 😂
What intrigues me, is that in KSP I just do it "by the seat of my pants" - but how do they do it in real life? How do they find the balance between computer-controlled precision and human flexibility to react to unpredicted situations?
My next metal band is gonna be called "100% Fratricide"
Are you an only child? ;)
Each of your videos is a master piece
For some reason I always see your comments!
Agreed! Very informative and interesting.
I enjoyed this video
I feel like your educational videos on the mechanics of spaceflight are such a great way to supplement and build up watching the actual launches. Anyone can watch a launch and be impressed by hardware involved, but knowing just a little more makes it even more impressive to see these engineering marvels work.
4:30 - Reminds me of my Nerv-powered upper stages and spaceplanes...
Slight correction: The RL-10 can be scaled up quite a bit, which is where the RL-60 comes from. Though it's probably not worth starting up a new production line when a new thrust structure and twice the engines will do a good enough job.
Why do kerbal mods look better than ULA animations?
A shortage of 3D artists in the space sector, and a lack of space-themed 3D content generally.
ULA also has no need to spend precious funding on better looking simulations.
Games endeavour to create realistic seeming graphics. Space programmes do not want people confusing animations with reality - although from what I've seen that hasn't stopped Americans. xD
You mean the in-flight footage, such as 4:07 and onward?
Perhaps it could be because the Atlas V dates back all the way to 2002, so there is a chance the animations are from that era too. And when you consider that around that time you had games like Morrowind, Vice City, or Battlefield 1942, I think these animations don't look too shabby. They don't need to look fancy after all, just give a general idea of what is going on.
SpaceX doesnt look too bad
Therapist: Atlas Heavy isn’t real, it can’t hurt you.
Atlas Heavy: 0:46
*Silent screaming*
I appreciate the amount of research and effort it takes to pull even one of these videos together, but you are cranking out content like crazy. I hope you have staff behind the scenes helping you pull all this together...otherwise all work and no play won't make for a happy Scott!
I used to play games on the channel, but nobody watches those any more.
Your passion for the subject matter and your explanations make this channel one of my favorites.
The various topics which came from you always fascinate me. Well done Scott!
Congratulations with the 1m subs! I have enjoyed every video you made and got along back in 2014 with the ksp videos! Thanks for all the great videos!
This is point in career mode where I get frustrated because I haven’t unlocked big enough engines to launch anything worth while.
A question I have had for years finally answered. Thank you Scott!
Very interesting. I love videos like this where you explain what's going on in upcoming space news.
Thank you, I was literally just last night reading about cst-100, wondering when it was launching. As always, quality video.
I always learn a ton here. Great video, man!
Incredible analysis Scott , great work!
Good to see so much hard work being put into making future spacecraft as safe as possible
You tube recomended me this 1 day before starliner lanch in 2019, good job you tube :)
Great video btw, you explained really well stuff that i read at various sources last few days, that didnt go so deep into that. XD
really interesting video for the evening, thanks scott!
It will be nice to see dual engine Centaur upper stages again since I like the iconic layout with 2 RL-10 engines :)
However I think the RL-10 is really pushed to its limits in terms of future manned missions. They should really continue with the J-2X development and use it as upperstage engine for the SLS instead of clustering RL-10 engines like on the Saturn I.
Definitely agree about the RL-10. I always liked the idea of using a modified RS-25 on the upper stage instead of the J-2X. The European Vinci seems like a very capable vacuum engine as well. My understanding was that development for the J-2X was rather costly even as rocket engines go.
@@chriskerwin3904 It was costly due to it being the underfunded Constellation program in which the rockets themselves sucked more funding than they anticipated. The J2X was very close to final design as they even tested the prototype engine to see how well the gimballing system would work.
Seems to me that you would want to use pretty much _anything_ but the expensive and rather weak RL-10 for a giant upper stage like that. RS-25, J-2X, Vinci... Hell, let's bring back the LR87-LH2 and bolt one or two of those bad boys on the stage, that thing was fun.
Well, the reason for the RL-10 is the relatively recent trend of small upper stages. For example, the Saturn I's upper stage is larger than ICPS, and the Saturn IB's upper stage is likely larger than EUS. RL-10s are perfectly sized for these stages, since thrust isn't what they need.
Also, the RL-10 shouldn't be expensive. I wonder how the space program would be if we had more engine production companies...
Yeah, the LR-87 was an impressively robust engine. It was able to operate on KeroLOX, HydroLOX and Aerozine 50/N2O4.
Nicely done on this video Scott!
7:13 and i though that this only happened in KSP.
Normally that's when I revert and either add more boosters, or try to get a better launch profile. In real life, when something goes wrong, you have to keep playing it out, and try to save what you can.
I didn't see your comment before typing mine, lol
ahahahahahahaha
@@Br3ttM Nope, irl the simulator also reverts and adds more boosters when it's hopeless but the simulator tries to get to orbit as much as he can. We just don't see it when he hits Esc. Sometimes, he's just too lazy to revert and then we have explosions. Remember the F9 kraken on launchpad? 😂
NASA needs to find a way to quick-save.
We can only hope that during the next Starliner test flight we actually DO get to see those dual RL-10s in action.
Still disappointed that even the post flight videos didn't show them.
Can’t wait to fly on that rocket! Great video Scott, that explains why my KSP RSS Atlas V upper stage kept falling back to earth
I get excited every time u make a video
I must admit that I was surprised to learn that the original unmanned moon Landers, the Mariners I believe, used centaur upper stages. I thought how long have they been flying these things? I'd love a history of the centaur rocket video or a pointer to a good reference.
He already did one.
1:18 I suppose calling it an Atlas 5 022 would be too obvious!
or replace 0 with C for capsule
My point is, why would you put a letter in what, until now, has obviously been a numeric field?
Right?!?!
They some dumb smart people ;p
No, the Atlas V 022 is a special-order variant with a 0 meter fairing, which costs the US Government $10 million extra to produce.
I was thinking they would simply put a dash :)
Congrats on 1million!!!!!!!
Love these type of videos
Really looking forward to seeing the Dreamchaser flying in the future.
So the reason is "MOAR BOOSTER!"?
yes
They've got a fever, and the only prescription is more engine bell
MOAR!
You’re awesome Scott!
That was cool to watch one of your videos from a year ago. ...and I happen to notice 999K subscribers, wow
Fascinating insights. Incredible.
Really enjoyed this. Ty
Scott, one would've thought that NASA would've paid the ULA to fly several of their Atlas Centaur V's with the two-engined variant in order to man-rate it ahead of its use by the Dream Chaser and CST-100.
Who's here after Boeing's successful Starliner failure?
Aye
Bingo
Which one?
Task failed successfully
Atlas 5 series also has significantly less payload compared to 4 series due to the much larger payload fairing and the small burnout mass of the first stage meaning that even a few extra tonnes of fairing reduces the mass ratio by 5-10%.
Nice updates Scott! I don't know if you ever made a comparison video of the various crew capsules and what will be the differences, but if not, please explain this topic!
That's gonna be a long video. I bet the differences go more than just aero, attitude control, abort procedures, mission profiles, landing, emergency egress, loading, mounting.... I'm getting pumped up! That's gonna be a good long video! Please do it! Please please please!
Has Scott gotten past the hacker episode to the point where youtube will let him do long videos again?
I just think he realized that it is more efficient to make short videos. The other option is to make videos like Curios Droid, which takes a lot of production time and preparation, that's why CD's videos are way better than Scott's, but CD can't upload multiple times a week. So let's be happy we have one guy who uploads multiple times a week and one who polishes the fascination for aerospace and science in general. And btw, he could explain a lot of differences in 10 minutes.
Very Cool, as usual
The expander cycle that RL10 use can be scale up with 2x of thrust, the Pratt and Whitney RL60 feature 2x of thrust of rl10. NASA or other launch provider just don’t want to pay more money into development of a new upper stage engine and end up with only RL10.
6:20 so they aren't allowed to use tweakscale?
At least they can use Engineer Redux mod.
Good one, Scott. More on CST 100 info, please !!!
I'm going to america soon, so I might be able to watch this launch live!
Have you ever done a video of ideas on how to address the orbital debris problem? I would be very interested to see what the realistic suggestions on how to work on this problem look like.
I enjoyed this video
The Starliner recent test flight was good........ launch and landing were spot on, that was critical. The rendezvous with station had to be cancelled, but it will work on the next flight, with crew !!!
I was wondering why they were using the dual engine, thanks!
By contrast, SLS Block I will fly with just the single RL10 engined ICPS upper stage. Is this because the SLS Core Stage puts the Orion capsule and the upper stage very close to being in orbit, so no lofted trajectory required for the ICPS to make orbit?
The SLS core stage will put both above LEO, though still with an atmospheric periapsis (not strictly necessary, just so that the core stage will deorbit). All the ICPS will need to do is make the periapsis positive and finish the transfer.
100% fratricide chance for the aries 1 lol
You didn't demonstrate this classic problem in KSP i noticed. its a really common beginner mistake of too little thrust for the payload.
It would be intresting to get a breakdown of types of rockets and there % of success rates and suchlike.Great channel for a non technical dude like me.
Having 1 engine where possible is good, if you need more engines then 3 and 5 are better options for thrust symmetry.
5:13 Eyeballs In
Thank You.
Watch 6:41 with autocaptions on. It turns "Cygnus OA6 Launch" into "Sickness Always Sex Launch".
"I am fluent in over six-million forms of communication, and RUclips auto-captions isn't one of them..."
7:11 it doe surelly looks like one of those almost failed launches in ksp
Why this video has those dislikes? There is nothing to dislike, it's just an informational video. I am confused.
People who dont believe in space mostly
I'd be interested in a in detailed discussion about various abort modes for the various manned spacecraft and these "black-zones",
Hi Scott, at about the 5:00 mark, you said the study did manage to find a way to bring an Atlas V401 just within limits.
1. How was it proposed that this be done, and
2. Why then does CST100 "Starliner" require a dual engine centaur?
Thanks.
Plus the two SRBs. This is just a guess on my part, but maybe there just wasn't enough of a safety margin: just shallow enough a reentry not to burn up the Starliner as well as barely avoid the "black zones", requiring nearly perfect flight profiles and abort sequences. The second RL10 provides a margin of safety for the second phase of the flight, while the two strap-on SRBs provide a margin of safety for the first phase, both of which would be stressed by the required flight profile without the extra energy/thrust. The Atlas V is a great rocket, obviously, but it was never designed to be human-rated and is not an ideal fit for this purpose, so a heavier configuration than one would normally expect is needed to provide adequate safety margins. Additionally, when the requirement for a second RL10 was made, this ate into the first stage's performance, hence the addition of the two SRBs. When only one RL10 was originally thought to be needed, no SRBs were planned to be used, but changing one part of the system often forces changes in other parts, of course.
The key is to flatten out the flight profile to allow for safe abort modes for humans--instead of the first stage lofting the second stage way higher than required to allow the low thrust of the RL10 enough time to circularize the orbit, which is how the Atlas V normally works, the second stage (Centaur) needs more thrust to circularize the orbit more quickly with a flatter profile (or else it won't make it and will reenter due to Earth's gravity). The reason the normal Centaur has such weak thrust is that having only a single little RL10 makes it incredibly light and therefore efficient. Two RL10s make it much heavier and therefore less efficient, which is probably why the first stage needs help from two SRBs instead of having none, as originally planned--they give the whole system the energy it needs to carry an extra engine on a more challenging profile.
By the way, even the Falcon 9 has to fly a somewhat flatter-than-normal profile, despite being a more standard design with a powerful, high-energy (but heavy) second stage. While this does not impact its configuration, it does require its reusable first stage to land on a barge at sea instead of on land (where it would normally land with a load of that mass). This gives it the additional performance it needs to fly with an adequate safety margin for humans.
I've never even played the game, but you've got my brain reading "KSC" as Kerbal Space Center. :-D
How on earth does this guy have the time to:
1) find all this info
2) make these videos
3) have a full time job
I learned something, happy days....
That launch is coming in a few days, I had a view of the bimotor centaur in Smarter Everyday's video, and made some guesses but had to reconsider everything after this explanation. And had to watch the video twice for a full understanding. None of this knowledge came from my aerospace engineering Msc
I spaced out for a minute and when Scott was saying “dual” I heard “juul.” I had to rewind and make sure that I wasn’t going crazy 😂
N22 could be a follow up to the N1 xD
Those fairings on the right in the drawing at 0:17 are interesting. It looks like they add a lot of mass and unusable volume by enclosing both the second stage and the payload. I'm assuming there's aerodynamic issues they are compensating for? Makes me wonder if I should be starting my fairings in KSP just above the 2nd stage engine.
Nah, in this case it's a necessary evil because the Centaur only has a 3-meter diameter. Putting a 5-meter fairing on top would probably put too much stress on the rocket. The Centaur was designed for the old Atlas D from Project Mercury, not the beefier Atlas V.
im pretty sure its so that there is more room for larger fuel tanks.
Scott, please elaborate on the difference between expansion cycle engines and the other types. (Have you already done a vid about that?)
ruclips.net/video/4QXZ2RzN_Oo/видео.html
Brilliant! Thank you!
"I'm Scott Manley, fly safe."
[opens Steam, launches KSP]
"Flying safe..." then appears on the loading screen.
new Vintage Space video premiering
I covered my second stage with a fairing in KSP once, I'm not sure why. Hadn't realized that was an actual thing that NASA did though.
Was thinking it was to keep it from rolling. Mhhhh, can Imagine it having both as a reason
I've had the experience of the 2nd stage struggling to make orbit in KSP when using the nuclear rocket. Much higher delta-V, but much lower thrust.
I'm a bit confused about the current Atlas versions. I worked on the original Atlas at Astronautics in San Diego, as well as the Centaur, and there is virtually no link between the original and the V, other than the names Atlas and Centaur.
6:57 I have done this in KSP more times than I care to relate....
Fly Safe!
And having insufficient second stage engine thrust, so you're struggling to accelerate your payload to orbital velocity is the thing Kerbal Space Program can teach you! 😊 The same as falling from 270 kilometers on a steep trajectory is not exactly a good idea.
And yes, dual engine Centaur looks cool!
The amount of black zones for the Shuttle is terrifying.
They learned that the hard way with _Challenger._
Sorry this isn't related, but are you going to talk about how the hole on the ISS turned out to be a drilled hole rather than a debris strike?
The Soyuz capsule has 2 layers of metal with foam in between. The hole in the inner metal layer was drilled and probably it has been there unnoticed for a while. The hole in the outer layer was microdebris. Only when both layers had a hole there was air leaking. Since they couldn't fix the hole in the outer layer they patched up the inner hole.
Someone made a mistake during assembly and drilled a hole in the wrong place, classic russian space engineering.
Looks like a Crazy Cosmonaut was trying to mount a bracket...used too long a drill bit...Whoops..!
I’ve seen some diagrams of ULAs Vulcan and on it they have a 4 engine upper stage centaur
That's ACES
N22? Why not just 022? N22 sounds like some obscure model number, not a booster config. :(
Also, what caused that one Atlas CBC to crap out before its burn time was over?
The issue on the OA-6 mission was with a mixture ratio control valve (MRCV) on the RD-180 engine. The valve erroneously reduced the amount of fuel being fed to the engine. Sensing that the engine wasn't producing enough thrust, the avionics increased the amount of oxygen being fed to the engine, which in turn increased the thrust back up to normal levels. However, since the rocket was consuming more oxygen than intended, it ran out of oxygen earlier than intended, which is what ultimately caused the engine to shut down early.
“Hopefully launching early next year”
I’m still saying that
And I thought too low thrust on 2nd stages resulting in desperate fights against gravity, was something you only get in KSP.
Check out the Saturn V launch profile, you have to loft the second and third stages at a higher angle because they have anemic thrust. You will be falling as you circularize. IIRC Angara V was similar last time I launched a replica in RO/RSS. I have a better launch record with Angara V though, Saturn V is a fickle beast.
The Saturn V is supposed to enter into a very low orbit, almost dipping into the atmosphere...
@@badbeardbill9956 Yeah, the Saturn V's parking orbit on lunar missions was only 93 nautical miles compared to 160 on a typical Gemini mission. It would not have taken long to fall out of that orbit, but they only stayed there long enough to doff their suits and get the "Go" for TLI.
@@CountArtha Yup. Parking in such a low orbit helped performance, and iirc the later missions went just a little bit lower than the earlier missions to squeeze extra performance out of the vehicle.
My *immediate* assumption on the reason for a dual-engine Centaur was *not* for larger payload but rather to provide the systems-redundancy demanded of human-rated vehicles.
The Vulcan would probably launch the Dream Chaser nowadays.
I'd much rather have a safer de-orbit with the two engine upper stage, rather than a single engine that would put me at 10-11 G's for an extended time period during re-entry.
Good
Okay so adding a second RL-10 engine to Centaur helps by 1) increasing redundancy, and 2) results in a more horizontal flight path at the time of abort so reduces reentry loads/acceleration, avoiding a ballistic trajectory. Is this correct?
Seeing as abort is only performed in case of emergency, and that crew have survived ballistic entries many times before (Vostok and Voskhod nominal entry mode was ballistic and experienced 8 g's, Apollo nominal entry was 4-6 g's, and Soyuz T-10 pad abort experienced 14-17 g's), it seems like a lot of effort to design, analyze, and qualify/test a new system of adding a 2nd engine all in an attempt to reduce g's experienced in a contingency scenario which we have already know is survivable. Yes it would be harsher on crew, but it's a backup for emergency only and hopefully is never used
Mmm I guess space x saw this and was like "hold my beer " lol
I'd love to see a video on the expander cycle mentioned in this one!
ruclips.net/video/4QXZ2RzN_Oo/видео.html
Just out of curiousity, if the two-engine Centaur hasn't been used in 15 years, then how is this Atlas V 5N22 getting a man-rating? Are they going to have to rush through a lot of test launches?
I thought a big part of why Dragon was being delayed was because of relatively minor tweaks to the Falcon 9?
Dragon wasn't delayed Crew Dragon was
It probably was because NASA never considered the CST-100 Starliner and the Crew Dragon as a replacement of the space shuttle
They need to fly the new configuration twice to get it man-rated. Normally it takes three, but NASA gave both commercial crew providers a waiver for the third flight because Falcon 9 and Atlas V were already reliable as unmanned launchers.
The second test flight of Starliner is happening in about two hours, so if it goes according to plan (this time) NASA will probably give ULA permission to fly astronauts.
I get the one solid boost variant does the power slide thing... But why do the other variants have asymmetric booster layouts?
When the Atlas V was first designed, it wasn't meant to have solid boosters. As such, there are some elements of the rocket that stick out the side (including hardware originally designed to support a "Heavy" variant) where boosters would normally go. Later on in Atlas V development, they realized that boosters could make a big difference in terms of payload and cost, and instead of going back and changing the surface features, they just attached the boosters to places where there wasn't anything in the way. This is also why the Atlas V is limited to only five boosters - there isn't enough space for more. ULA's next rocket, Vulcan, is being designed to support boosters from the beginning, and thus is able to mount them symmetrically, and carry more than five.
@@adamdapatsfan very interesting. Thanks for the reply!
Can anyone explain the dreaded "black zones" diagram for space shuttle at 3:16 in this video? Thanks!
Certain failures at certain times will kill you. Example, losing all 3 main engines during the solid rocket burn. Also, losing 3 engines soon after SRB jettison.
Anyone notice the shielding at the end detaching and floating by the stage before then engine started?
they are covers protecting the docking mechanisms
This reentry and launch black zone stuff could also be filed under "Things KSP doesn't teach." I don't think I would have very many surviving Kerbal's if my reentry trajectory mattered.
There should be a mod that causes the kerbals to have a 50% of being killed if you do a bad re-entry.
But there is a G-force limit option for parts and kerbals even in vanilla.
1,000.000 subs
Does this mean , that a droneship landing is more suitable for crewed dragon?
Maybe it is
Can you answer why the Centaur upper stage and Starliner has that odd structural shape. What I mean is that most of the atlas fairings widen out and then narrow back down into the vehicle, but with the Starliner there is that overhang due to the size of the capsule. Why has Boeing or NASA or whoever designed it like that?
That's because they had issues with aerodynamics without them.
The Centaur was designed in 1962 for a skinnier version of the Atlas rocket. The Atlas V first stage is about 4 meters wide, but the Centaur is only 3 meters wide. The Starliner is half again the diameter of the Centaur (4.56 m), so I assume the skirt is there to prevent an unrecoverable yaw from too much drag on one side.