Delta Rocket History - Part II - Legacy Of Thor - America's Most Successful Rocket

[@mattcolver1]

I had quite a few very busy years at McDonnell Douglas and then Boeing. I worked on the development team for the 10 ft Composite fairing for Delta II then went right into Delta III developing composite structures for it, fairing, payload adapter and interstage, then right into Delta IV developing fairings and payload adapters. I worked 7 years where Saturday was a regular work day. I was at the 1st launch of Delta III and was heart broken over the failure. I was at the 1st launch of Delta IV and it was a much better day. Then we became ULA. When Vulcan development was announced I assumed I'd be part of that development, but all composite structure design was subcontracted out to RUAG. So I grabbed a nice severance package and retired at the young age of 61. I had an enjoyable career.

[@msudawg1997]

It's always interesting to me how this industry is really kind of small and it's easy for people's paths to cross in various ways. Although our paths never exactly crossed, there are similar twists and turns. I started working for Rocketdyne at Stennis in mid-97 as they were in the transition to being bought by Boeing from NAA. While I was primarily working SSME for SSP at the time, I did support Delta IV Common Booster Core testing at SSC. I left Rocketdyne for NASA in Sep 2001 and eventually left Stennis for MSFC in 2009. Nowadays I work structural test at MSFC and one of our customers is RUAG- for some of that Vulcan composite hardware you mentioned. BTW, they recently changed their name to Beyond Gravity. LOL.

[@jeromethiel4323]

You got to live the dream! Cherish that. A great many people live their lives and their contribution to society doesn't amount to much.

[@mattcolver1]

@@msudawg1997 Yep had an interesting career and now have a comfortable retirement. Travelled all over the world after i retired, before COVID hit. Even camped in Antarctica.

[@msudawg1997]

@@mattcolver1 that's awesome! I hope to be able to travel one day but I've got to put in at least 9 more years with NASA. And because I waited late in life for kids I've got at least prob 15-17 years before I can think about actual retirement.

[@mattcolver1]

@@msudawg1997 One of the benefits of going to ULA is that I was able to start drawing my Boeing pension at age 52 allowing a nice double dip for almost 10 years. We've been to all 7 continents. I've fallen in love with the southern hemisphere. Less human civilization and unique wildlife.

[@kerbalengineeringsystems7415]

Here's my thought process on Delta Nomenclature: Once a major piece of hardware flies on a Delta, it becomes "Delta hardware," thus making any future vehicles including it eligible for the Delta name. So once the Delta Cryogenic Upper Stage flew on Delta III (which was unquestionably a Delta rocket), it became part of the Delta family and can transfer the Delta name onto any rocket that flies it, thus making SLS Block I Delta V. Once the ICPS is retired for Block II, it's still a Delta family rocket, since by the same logic the SLS core stage has become Delta hardware, meaning that it can carry the Delta name to Block II. By this logic, then, SLS Block I is Delta V, and Block II is now Delta VI. This is flawless logic and I'll be taking no further questions at this time.

[@brianchan8]

Since sls is a delta now, we need to increase the srb count from 2 to 8

[@kerbalengineeringsystems7415]

@@brianchan8 I fully support this

[@Condorito380]

The Delta of Thesius, if you will. I will not, myself.

[@brianchan8]

@@kerbalengineeringsystems7415 well why stop there, there where plans to give the SRBS 2 smaller boosters, thus increasing the amount of boosters and making it better

[@kerbalengineeringsystems7415]

@@brianchan8 Just do boosters all the way down

[@cosmicinsane516]

Glad you mentioned that Delta II launch failure. That’s probably my favorite rocket explosion of all time for two reasons. First, it was seriously spectacular with the massive fireball and thousands of burning chunks of SRB falling all over the launch site. Second, the commentary on the launch had what was probably the best example of understatement in history “We have had an anomaly…”

[@oldfrend]

she must've been trained in bullshit PR, like all her ingrained instincts told her to NOT CALL IT AN EXPLOSION or some shit.

[@CrazyMrTim]

I was in school that day and it sounded like a bomb went off

[@RWBHere]

@@CrazyMrTim It definitely bombed.

[@CrazyMrTim]

@@RWBHere lol yep, I remember the shocked look on my teacher's face

[@evanfinch4987]

Didn't dude's pickup get melted when he was working in the LCC bunker; he claims he called his insurance and was like pop on the news for proof of covered loss.

[@rosswarren436]

Love it! "Delta" lives on a little longer. Can't argue with 700 missions for the "family". Guess that's as close as the U.S. will come to all the "Vostok/Soyuz" variants of the R7. I love the Falcon 9, but for many of us, when we think "rocket", that blue-green Delta II will always come to mind. Just FYI: It took about 10 gallons of AkzoNobel's aerospace coating "Blue Fluid Resistant Primer" to cover a single Delta II. Between 1989 and 2018, 155 of the rockets flew. Outside the space program, "Delta Blue" is formally known as Federal Standard 25193. Considered a shade of cyan, it is comprised of 36.47 percent red, 55.69 percent green and 58.82 percent blue. Delta Blue has an approximate wavelength of 488.02 nanometers. Pantone, known for its color matching system, identifies "Delta Blue" as simply "5483-C." If you wanted to paint your rocket - or your room - Delta Blue then you could look for Dutch Boy's "Midnight Run," Sherwin-Williams' "Mountain Stream" (no. 7162) or Valspar Paint's "Ocean Voyage." If you wanted to order your next car in Delta Blue, Chrysler's closest match is "Neptune Green," General Motors' offers "Adriatic Turquoise" and at Ford it is just "Medium Turquoise." To the McDonnell Douglas, Boeing and United Launch Alliance teams that worked on Delta II for three decades though, it was and continues to be "Delta Blue."

[@Gapsx1eGewehr]

Honestly, SpaceX's rockets will always pale in comparison to NASA's greats of the past. They just ooze the vibe of rocketry, while SpaceX's rockets look a bit... too clean.

[@rosswarren436]

@@Gapsx1eGewehr I think the basic white of the Falcon 9 is due to having to reject as much heat as possible in the hot Florida sun, especially with their using "super cooled" LOX and RP-1 to increase their density and hence the performance of the rocket. But yeah, it lacks "character" without even a single roll pattern on it.

[@thedabblingwarlock]

@@rosswarren436 Well, at least until the booster's been up a few times, then it has a bit of character. That said, I was born in 1989, but when I think rocket, I always think of the Saturn V with the black and white scheme and roll pattern on it. There's just something about that monster that speaks to me.

[@motokid6008]

With all the performance they were trying to squeeze out of this family of rockets im really surprised they kept the paint job.

[@Gapsx1eGewehr]

@@rosswarren436 I didn't know about the heat rejection paint, actually It makes a lot of sense now that I think about it though!

[@msudawg1997]

16:40 minor correction: At the time Boeing was developing Delta IV, the RS-68 was being developed by Rocketdyne. Which itself was also owned by Boeing. When Boeing bought McDAC they also around the same time bought Rocketdyne from NAA. It wasn't until many years later that UTC, who owned P&W, bought Rocketdyne from Boeing and created Pratt&Whitney-Rocketdyne (they went by PWR). I remember all of this fairly well as I worked for Rocketdyne at Stennis from June 1997 until Sep 2001. When I hired in we were being called Boeing North American as they were working out the logistics of combining the companies. It was some time after I left Rocketdyne for NASA in Sep 2001 that P&W bought them. So to the point, you could say the RS-68 was a Boeing engine at the time they developed D-IV. As a side note, I supported the D-IV Common Booster Core testing at Stennis. My main job at the time was running SSME tests on A-2 test stand but I got to work LH2 fill of CBC during test. Those were fun days.

[@msudawg1997]

Per Wikipedia, P&W acquired Rocketdyne from Boeing in 2005

[@j99450]

I was going to say pretty much this, Boeing did own Pratt, but it was only for 5 years from 1929 to 1934

[@msudawg1997]

@@j99450 I did not realize that Boeing owed P&W way back then. Thanks for that info. I'll have to go read up on the history of P&W.

[@ethansigh]

The Delta II holds a very special place in my heart since I'm lucky enough that my cubesats flew on that final launch with Icesat2 in 2018! Thanks for such an awesome and informative video Scott!

[@ronjon7942]

Heyyy, tell us more about your sats! Pretty please!

[@frankgulla2335]

Scott, you are the man of the subtle irony. "SLS is a Delta" Fantastic. Thanks for this detailed history of a major launch vehicle.

[@aninditabasak7694]

No it’s more of a Shuttle.

[@deusexaethera]

It was an immensely stupid decision by NASA to not build a 5th version of the Delta rocket, named Delta V.

[@kamipollna225]

It only adds more Delta V lol

[@dotydude]

My first job out of college (Parks College of Saint Louis University) was testing Delta II Second Stage bi-propellant valves with water at Aerojet. Once I mastered that task they let me hot-fire test the whole engine. It was very reliable and I never had a failure.

[@matthewkubinec1620]

Considering SLS to be part of the Delta family because of the second stage makes sense when you remember from the first video that Delta was originally the name for the upgraded Thor second stage. So really, the common factor of a Delta rocket is the second stage lineage, not the first stage.

[@1224chrisng]

which also means that Delta lost heritage with the Delta 3, so Delta 4 was never a Delta to begin with, nevermind SLS Blk-1

[@fork9001]

Then how does OG Atlas become Atlas V? Centaur upper stage?

[@simongeard4824]

And let's be honest, the SLS architecture is a very close cousin to Delta IV. An upper stage that's a direct derivative of the Delta one, a hydrolox core which at one point was intended to use the same RS-68 engine (until they realised it would cook itself, and switched to the RS-25), supplemented with SRBs to get it off the ground due to the deficiencies of a hydrolox core.

[@THEncrtrooper]

​@@fork9001 Core stage tank. iirc the Atlas III mainly changed the engines & the Atlas V extended it.

[@stefanschneider3681]

"Down from 10 to 6 PER YEAR!" I first thought I misunderstood, but then I remembered: There were times before SpaceX, Rocketlab etc ... Great video as always, thanks Scott!

[@Diskpartitional]

Yes, 6 launches per year seems pretty insane these days. It's funny to think that we had that many launches in a day a few days ago (albeit spread out across launch vehicles).

[@scdallav]

6 per year is fairly typical for ULA

[@joyl7842]

I love the Delta IV Heavy. It looks so awesome, plus it runs on hydrogen! Also, it just kicks butt that it lights itself on fire T-0. What a vehicle.

[@denysvlasenko1865]

"Looking awesome" is subjective. Running on hydrogen is stupid for the 1st stage.

[@cube2fox]

By any chance, was the Falcon Heavy design -copied from- inspired by the Delta IV Heavy? I mean they both strap on what is basically two extra lower stages on the side. SpaceX even copied the "Heavy" designation! (Of course with the Falcon Heavy this design makes even more sense since the three booster stages all come back!)

[@joyl7842]

@@cube2fox It may look similar because it's basically 3 of the same boosters strapped together, but they are vastly different vehicles and don't even run on the same fuel. Plus, have you ever seen a Delta rocket land and get re-used?

[@ExtroniusAttributes]

@@cube2fox: Before there was Delta IV Heavy there was Titan III, which is (I think) the first "3 x 10' cores" rocket to fly. Of course, the Titan's two outer cores were SRBs while the center was a (stretched, I think) Titan II that didn't start its engine till the SRBs dropped off. You can go back further: if you don't get caught up with the shape and size of tanks, you can argue that the first "parallel staged" rocket to fly, and the indirect ancestor of the Titan III, Delta Heavy and Falcon Heavy, is Korolev's good old "Semyorka" R-7. One core, four side boosters, all powered by the same engines... Back in 1986, Newsweek devoted an entire issue to what was wrong with the Shuttle program, and made a fascinating comment in passing: that, in an attempt to design a simple heavy-lift rocket, McDonnell-Douglas had proposed a rocket whose first stage was SEVEN Delta cores strapped together. I suspect it's actually the reporter misunderstanding one of the Delta II solid booster configurations, but it would be a hoot if it turned out to be a real proposal and somebody turned up some design drawings!

[@Soacwiththaface]

Was at the last night launch of The Beast!!! Wont make it to port Canaveral this time but I'll be watching from 60 miles north.

[@simontanguay3619]

Very bold move adding SLS to the Delta family. But it's a bold move I can approve.

[@steffan10000]

Would love to see a series like this on the history of all the different Atlas variants leading into its retirement.

[@scottmanley]

I did a single video on Atlas a long time ago

[@rkornilo]

Great video as always, Scott. And I thought it was a classy decision not to show the actual explosion of Challenger.

[@MrFaaaaaaaaaaaaaaaaa]

Agreed. There are likely family members, co-workers, or friends of the astronauts in the audience. It's a small world.

[@DroneDocs]

Super excited about the Delta V launch coming up this year Scott! 😉 Fly Safe

[@rockysgarage]

Thank you Scott!! Just adds another layer of love for the Delta 2/4 rocket.

[@elmofeneken4364]

Scott, what a detailed, highly researched, informative Part II of the Thor/Delta story. Thumbs up! Nobody could have done such a thorough job on this subject. You nailed it!

[@minikawildflower]

This is such a great series - I've always been curious about what came before the Delta II, since you'd figure it was Delta I but it was really this long development of different models you've covered here. Thanks!

[@msimpson54]

Scott can you please do one of these on the Titan family at some point? Don’t really hear a lot about them often

[@jonminer9891]

Hey, Scott. It's just another Delta... Riiiight. Very nice program. Thanks for sharing! Stay healthy!

[@petequintanilla4237]

Watching this show for me is like playing golf. If I understand 20% of what Scott is saying, I’m happy. It’s a good day.

[@louissivo9660]

Thanks for the nice overview and history of this rocket.

[@edgeeffect]

I was a huge fan of Delta before you made this series.... after watching, I'm an even bigger fan! Great series... thanks loads.

[@GonkDroid0923]

Oooh you should do the Titan Family of rockets (1959 -2005)

[@connecticutaggie]

LOL - "SLS is just another version of Delta". Great punch line, and a nice way to end the series.

[@charlesmiller1446]

A masterful Delta history! Thanks Scott

[@blackberrymw]

One of the best videos of the year so far. Keep it up.

[@jonathandixon3544]

What a great series. Thank you Scott!

[@paulkinzer7661]

So well presented! Pretty much a book's worth of knowledge in less than 22 minutes.

[@etrain757]

I want to say that I love these rocket history videos! I hope you’ll do a titan history too

[@joyl7842]

0:50 yes people! That's a white fuel tank on the Space Shuttle (only on the first two launches). The orange one came afterward and is thanks to the findings that the white paint wasn't necessary for its purpose (ultra-violet protection) and leaving it off saved 272 kilograms.

[@dillonbledsoe7680]

Who asked?

[@benbaselet2026]

@@dillonbledsoe7680 Maybe someone did, but most probably said "oh that's an early launch" when seeing the white tank :)

[@MrViki60]

@@dillonbledsoe7680 your mom

[@MonkeyJedi99]

@@dillonbledsoe7680 Wow. Who peed in YOUR cornflakes this morning?

[@ronjon7942]

I painted my shuttle model’s tank white; thought it looked better, but maybe that was an 80s thing. I like the naked look now.

[@AsteroidWrangler]

I know I have a deep seated love of ugly rockets, because something about the Delta III makes me happy and always has.

[@jaydonbooth4042]

While reading press releases and stuff for upgraded boosters recently I saw a strange graphic from NASA of an SLS in Delta II teal, and wow that would've looked great, I don't think it was ever seriously considered but for whatever reason someone decided to make a little blue SLS for a info page and it's a great "could've been".

[@RCAvhstape]

Those graphics are fun sometimes. There was a graphic for the now-abandoned Ares V rocket (which morphed into SLS) which showed it with black and white pattern similar to the Saturn V, obviously a ploy to drum up enthusiasm for the project by making it look related to the coolest launch vehicle ever flown.

[@jaydonbooth4042]

@@RCAvhstape Yeah I've seen those old animations and graphics of it looking like the Saturn V paint job. I would've preferred either alternative, black and white or delta blue, to what we got with the orange, I think the white painted space shuttles look so much better. But I get it, even unpainted SLS's payload cap is pretty disappointing as of now.

[@ItsNova816]

The Artemis Kit mod for Kerbal Space Program gives you the option of painting SLS in Delta blue ;)

[@eaofdeath187]

I'm playing KSP with the RP-1 modset once again and I always find myself building a Delta and Titan clone, both are very adaptable.

[@pixelkatten]

I had no idea that the Delta had a miniskirt! Thank you for showing us what was under it!

[@Truck_Company_84]

I have always, and will always love Thor and the Delta I through III rockets. I miss the Delta II sooo much.

[@williammodlin2621]

Hey Scott, what an information rich series about this historic rocket. I can remember the Thor from my childhood, so it’s been great to see the full panoply of this rocket’s career. You probably have a book in this! Thanks for the hard work and deep digging.

[@santiagorivero6074]

A few years ago my neighbour found in his farm a delta ii solid Upper stage that reentered earth's atmosphere, the uss governent came and gave him medalls and invited him to the united states but he didn't accept the offer. He showed me the medalls and told me the story when i was younger, it inspired me to learn about rockets.

[@santiagorivero6074]

The Upper stage was launched in 2003 to Mars by NASA according to a news article,probably oportunity or spirit launch and it fell in Artigas,Uruguay in March 2011

[@sukubann]

astonishing Thor / Delta history, thank you very much

[@evgSyr]

These ballast jokes never get old.

[@Stant123]

When Scott Manley says he was "unlucky enough to have his car break down while parked at the launch site." what he's really saying is he was trying to convince the base staff to let him stay for the next launch.

[@matthewcox7985]

Love the pun in the still at 0:09... Marvelous. 😁

[@NikitaWolf1776]

Make one of these for the Titan rockets next please? Either that or the Japanese rockets?

[@ChemEDan]

Scott Manley: Explains a bunch of *incremental changes* made to a launch system. Me: So that's why they call it *delta.*

[@ronjon7942]

Ahhh, nicely done.

[@michaelterrones4642]

Worked General Dynamics, Lockheed Martin, and ULA as a Quality Inspector. Total - 42 years. The Atlas missile outlived them all and is still going. The GOAT in aerospace!

[@dianapennepacker6854]

I wonder if you worked with my grandpa. He worked in around Lockheed, and maybe Douglas, and the nuclear industry. I think as an inspector or saftey in both. He didn't talk about it much at all sadly. I do know he, and people thought the engines were for a cruise missile. Couldn't beleive they'd attach a man to it let alone two. God I wish I actually learnt things from him!

[@donjones4719]

SLS is another version of Delta? Sir, the lawyers for the Delta family have just filed a suit for libel.

[@idigbebop]

Excellent review. I spent 27 years on Delta launch pads.

[@kenhelmers2603]

Really like this historical review! Thanks Scott

[@UpLateGeek]

That was a great dig about calling the SLS a Delta. You should totally call it Delta-SLS from now on!

[@TheAmazingCowpig]

Delta II Heavy, I just really like the thing; definitely somewhere on my top favorite orbital launch vehicles. I dunno, I think it just LOOKS right. A simple long tube, single engine at the bottom, and "added more boosters".

[@mikerichards6065]

Great video series - thank you Scott. Any chance of a similar one for the Titan?

[@topsecret1837]

After this do you plan on doing a detailed history of the Titan rocket Family?

[@howardjohnson2138]

I always like your presentations. Thank you for all the study and hard work.

[@LordFalconsword]

All those decades of launches, and Falcon9 has beaten it in just a few years. Truly astounding.

[@RollWithTheChanges]

I LOVE THE EXTRA-EXTENDED LONG TANK THOR!!

[@_mgde_]

So….history of Titan next??

[@MCsCreations]

Really, really interesting history, Scott! Thanks! 😃 Stay safe there with your family! 🖖😊

[@ZeroSpawn]

I came for the Scott Class, i hit the like button once i saw the shirt. I don't care what your ex says, you Rock! 🙌🏾

[@brucefrye8799]

Thanks so much Scott I've enjoyed this series

[@brucefrye8799]

Btw love you t shirt in this video

[@One_High_Guy_420]

I love to listen to you while im stoned.

[@NeonsStyleHD]

That shuttle launch. Interesting flare between the booster and the shuttle up near the top of the left booster. What is it? 1:09

[@iitzfizz]

Great series Scott

[@MrHichammohsen1]

I rewatched the previous two videos before this, and i think if you put them together like a documentary it would be amazing!

[@buttersPbutters]

The kindest thing one can say about Delta IV is that it was significantly less expensive than Titan IV, which was significantly less expensive than Shuttle. It's all relative...

[@richb313]

Thanks for the update Scott seems that years of experience cannot overcome changes in technology and more complicated mission requirements.

[@MarcusHollinger]

great video always loved the delta rockets 🚀

[@ryanrenolds]

You commented 1 Minute after the Video was published how do you know its good

[@MarcusHollinger]

@@ryanrenolds its a scott manley video

[@mikehenning1791]

Great video very insightful thanks please do more history videos on different rockets

[@BugsydorPrime]

Gotta say, those Graphite Epoxy Motors were truly outrageous.

[@zapfanzapfan]

"Ballast", showing image of astronauts... I chuckled 🙂

[@echoharmony926]

SLS definitely belongs with the Delta IV when you look at the cost.

[@ewetoo]

Got me with the benefits of rockets flying without unnecessary ballast" *shot of astronauts* 😬 And then Delta has a little disaster of its own...ugh.well played sir.

[@nathanel1313]

Well I guess it was mostly about one person of that crew

[@Joshs4stro]

can’t wait for the delta V launch in a couple of hours! 😁

[@JMurph2015]

There's something about the Delta IV Heavy that is just so kickass, what an absolute unit of a rocket. I know Falcon and Falcon Heavy absolutely outperform it, but I'll still have some nostalgia for the Delta IV-H

[@josephalexander3884]

Most of your math is beyond me; however please keep adding it. Great video, thank you very much. Excellent video, thank you.

[@jamesshutchison5297]

That was a wonderful series particularly for the corps of aging geeks. Thank you .

[@tomhill4617]

The Delta GOES explosion from 1986 has a guest appearance on The Martian as the exploding supply rocket.

[@matthewbond5028]

Oh wow! You were at Vandenberg for the last launch?! It was a great launch I crawled out of bed and drove out there to go watch it.

[@krazyhorse0074]

Well done Scott

[@georgemancuso9597]

Good to see an informational video

[@lonnieholcomb2078]

I enjoy this kind of video, always fun

[@rickstorm4198]

Great content Scott

[@bf1701]

Wouldn't it have been quite the memory to have the last Delta II launch melt your car to slag?

[@oldfrend]

i wasn't prepared for that plot twist ending! delta V go!

[@grahambuckerfield4640]

Maybe it lives on longer than we think, after all on the timeline of the movie, in 2036 a Delta had an identical failure to 50 years before when launching the probe to re supply Mark Watney on Mars!

[@mirien7277]

I'm definitely gonna start calling sls delta 5

[@KernelLeak]

I think Delta-V would be more appropriate...

[@gordonstewart5774]

Better than Senate Lobby System.

[@davidlabedz2046]

An interesting history of the Thor/Delta/......SLS, family

[@76luislara]

The Space Shuttle suppose to take over the Delta rockets, but after the Challenger accident, it was clear that NASA will never reach the cadence of 24 or more flights a year, so that's when Delta II was created and from 1989 to the earlier 2010s became the workhorse for NASA.

[@coolguy13333]

In school we did a thing where we had to make cool concepts in class and I drew something called: the delta 5” it was supposed to be a mix of the delta 2 and delta 3. the main rocket is like a esa Vega c rocket with boosters and a green second stage.

[@Globovoyeur]

As I recall, Air Force Secretary Edward Aldridge resisted the push to move launches to the shuttle, thereby keeping expendable booster production going. When Challenger was lost, he became a hero to the military.

[@NebraskaWarningSirens]

Delta 4: I do not want to go:( ULA:but you have served us well Delta 2 :what happened to me was I not good enough??

[@ExtroniusAttributes]

Notice how the design of one second stage (3:30 in the video) includes a "miniskirt." Delta was nothing if not hip to fashion.

[@rafaeldiaz6855]

Dear..regarding the Delta ..any book to buy...for more information ?..Thks

[@SusEngineSFS]

"You expected you were completely new, but it was I, Delta!" -Delta to SLS, probably

[@joyl7842]

15:32 that looks like a modified oil rig. Whatever happened to those Sea Launch platforms? Sounds like something SpaceX might want, or their specs, if they are still around.

[@scottmanley]

Currently docked in Russia

[@joyl7842]

@@scottmanley Thank you!

[@nobelchurch4338]

Thinking sls is the next/last delta variant is definitely a plus for sls in my book!

[@charlieturner5831]

What do you think of the James Cameron's Avatar space shuttle? Could the design work and are we capable of launching something of that size?

[@squidwardfromua]

...benefits of rockets flying without unnecessary ballast _showing shuttle crew_

[@dannypipewrench533]

Vulcan is essentially the child of Atlas and Delta. It, of course, will use Centaur as a second stage, a first stage with similar diameter as Delta IV, and the SRMs I believe are based on those used by Atlas. Alright, it is essentially a new Atlas vehicle, but the way I see it is if you built a Delta IV out of Atlas V parts.