SpaceX barrelling like a juggernaut toward first Starship/Superheavy orbital flight this year
Starship prototype #15 about to land, May 5, 2021
A series of articles at Teslarati in the past two days suggest strongly that the next Starship flight will be on top of a Superheavy first stage, and will likely be the first near orbital flight from Texas around the globe to splashdown softly in the Pacific Ocean northeast of Hawaii.
And it will likely happen this year!
First there was the report from locals in the McGregor, Texas, area indicating that SpaceX has completed a full duration launch burn of a Raptor engine.
A local resident and unofficial SpaceX observer has reported hearing a test of one of Starship’s Raptor engines that lasted more than five minutes at the company’s McGregor, Texas development facilities.
If accurate, it could be the longest static fire of a Starship engine that SpaceX has ever completed in the two years since full-scale Raptor testing first began. Whether it was successful or not, a five or six-minute static fire would also confirm that SpaceX is well into the process of qualifying Raptor for Starship’s first orbital launch attempts.
This burn is somewhat longer than the engine burns during the Starship test hops, and approaches the burn time required for Superheavy during a launch.
Next there was the report describing the newest known engine configurations SpaceX is planning for Superheavy itself, with the first version possibly having 29 engines and a future more powerful version sporting 32.
This high number of Raptor engines needed for the planned upcoming test flights, most of which will not be recovered, has also required SpaceX to accelerate its engine production rate, apparently completing one engine every 48 hours. The total number of engines on hand appears to be approaching 150, with that number likely doubling over the next year.
Then today was an additional story describing not only the anticipating assembly plans for Superheavy but also noting that the company is in the process of completing the first tank test on the second Superheavy prototype.
All in all, it appears that SpaceX’s Starship development program is now focusing itself entirely on that first near-orbital flight, which also tells us that this flight might very well occur before the end of the summer, an achievement that would be beyond astonishing.
The last Teslarati article also had this factoid about Superheavy’s anticipated capabilities:
With 29 identical Raptors, the simplest possible Super Heavy booster would produce up to 5800 tons (12.8M lbf) of thrust at liftoff. If SpaceX has already completed Raptor Boost’s design and qualification and kicked off mass production of a 250-mTf engine, that liftoff thrust climbs to 6800 tons (~15M lbf). If SpaceX achieves performance goals (~210 mTf stock; ~300 mTf RBoost) mentioned by Musk last year, a 32-engine Super Heavy could achieve peak liftoff thrust greater than 8500 metric tons (~18.7M lbf).
Even in its weakest configuration, Super Heavy will still be more than 60% more powerful than Saturn V and 25% more powerful than N1 – the largest rockets to have ever successfully or unsuccessfully flown.
Moreover, as designed, Superheavy will return to Earth, ready to fly again. And it will do it for pennies on the dollar when compared with the cost of both the Saturn 5 and SLS.
Finally, a story at Business Insider highlighted a tweet by Musk which stated that the refurbishment of one of two floating oil rigs, dubbed Deimos and Phobos, is aiming for completion next year. If all goes as intended the first regular orbital launches and landings will take place from these platforms.
All the pieces appear to be falling into place. The next year or so could be by far the most exciting year in space exploration since 1969.
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The “cap” sections being added to the orbital launch table legs at Boca Chica strike me as a probable design revision. I think someone realized that without a flame trench, the base of the launch table needed to be higher up above ground level. But with the angled orientation of the legs, extending them would result in a table base that was too narrow. So the only way to raise the table, was to extend the legs absolutely vertically, resulting in an odd dog-leg design.
If a SpaceX design doesn’t look right, it’s probably because it was a mistake that could not be corrected in any other way! Thoughts?
https://arstechnica.com/science/2021/06/the-us-military-is-starting-to-get-really-interested-in-starship/
I wonder if Starship’s earthbound cargo capabilities may turn out to be as commercially valuable to SpaceX as Starlink.
You need air superiority at both ends, but if SpaceX can role them out on a mass scale like C-47 Skytrains then they may have something.
I think that the angle in the launch table legs adds panache. Definitely not a mistake. Very artistic ?
I want to try to explain what I mean by a “design revision” in the launch table legs. A design revision could be required by a) faulty requirements, b) faulty design to satisfy valid requirements, or c) both!
From anecdotes about the skill and elegance shown in SpaceX engineering, I think b and c are less likely than a. This is also supported by Elon’s musings about misjudging the requirement for a flame trench. He didn’t say “We may have mis-judged the design of a flame trench”, he said “We may have misjudged the requirement for a flame trench!”. Important distinction. The difference is between mis-understanding the correct problem, and mis-understanding how to solve the problem.
Assume SpaceX determined that a deck height H above ground level would be required to obviate the need for a flame trench. If this is a correct requirement, the best design solution is obvious: a leg inclined to a degree that optimizes the size, weight, materials, etc. to give the right deck height and the amount of lateral stability required. A trade study Elon could probably do in his head! It would NOT include a dog-leg.
But let’s suppose SpaceX did not pick H correctly! How can it get to the new (higher) H without digging up the existing legs? It can put in a dog-leg. But, you say, perhaps SpaceX’s esthetics committee defined the dogleg as desirable! Okay, how would one implement a dogleg? Well, not like it has been implemented!
To make a join between two circular-cross-section tubes that subtends angle X, you cut a face on the end of each tube that is angled at X/2 from a right angle. You end up with two elliptical faces, but they are elliptical in precisely the same way! So for practical purposes, you can bolt them together nicely. And the stresses are distributed evenly too.
BUT that’s NOT what they did! Instead SpaceX cut the lower leg at horizontal just as if it would be bolted directly to the underside of the launch table, which I think was what was intended. But that means you now have to bolt a circular tube onto a tube cut elliptically! Yikes! I suspect the vertical tubes are elliptical, given that that such a joint would be a mess! And elliptical tubing of that size and weight… $$$ ka-ching!
BUT WAIT! If the vertical tubes are elliptical, won’t that screw up the hole pattern required in the bottom of the table? Nope. Think about it… it was always going to be elliptical! We just got there in a very expensive and dorky way! Which is why I think SpaceX missed the requirement for the value of H needed to avoid a flame trench, and once they realized it, those pretty inclined legs were set in concrete, so to speak. I couldn’t have been the only one who wondered week after week why that elegantly modernistic Stonehenge wasn’t being touched while everywhere around it was in churn!
I have made a messy argument here pecking away on an iPhone, but it feels like something is wrong with the legs of the orbital launch table, and above is my stream-of-consciousness cut at what it is!
I find it strange that they’ve decided to go almost orbital before they’ve tested the Starship at Max Q and the control conditions when transonic.
Sometimes I wonder if the pad is really pusher plate supports for pulse-ORION.
Sorry to say this, but I think it is N-I’s other record of largest non-nuclear pad explosion that gets bested-but Falcon Heavy’s flight was near perfect…fingers crossed.
Jeff,
That would be the coolest thing to see an pusher-plate Orion! Dyson would be proud!
Reading and remembering about the N-1’s history: not a lot of functional testing on the ground and there were quality control issues. I know there has been a lot published about the N-1 after the fall of the USSR, and even some of the numbers were a little fuzzy. I have seen payload numbers to LEO between 75 and over 100 tons.
SpaceX is being methodical in their testing of Super Heavy, I do not know what their Q.C. numbers are on the Raptor engine , but I do have to say that the Merlin engines have been pretty damn good.
“Apollo 4”
NASA film
https://youtu.be/n8FmR3OL36k
11:41
So he tells NASA, going to the Moon with out you.
RVD:
To your commentary about the design change to the table legs I believe you are over thinking it.
At this point the Starship/SuperHeavy program is only in the prototype phase, and virtually NOTHING is final yet. And, when things need changing SpaceX doesn’t wait, they switch ASAP using a Good Enough For What It’s For design mentality, not a quest for the most ideal, elegant, and optimal. And this holds true most especially I think when it comes to the ground equipment that has no long term utility with intended flight ops looking to be ocean platform based anyway.
This being the case the use of an optimal and elegant ellipse to ellipse joint in the leg may have been considered, but they went with the easier/faster/still good enough fix instead.
Initial modeling told SpaceX that they wouldn’t need a flame trench, but testing has proven the models were wrong and they are simply adapting to what reality is. Elon understands that models, especially complex system models, are limited in what they can really tell you. The real world almost never agrees and teaches you something new when you perform real and at scale tests. This is precisely why he has structured the program around rapid prototyping with a high tolerance for failure, because as the Cal Poly slogan from my era goes you “Learn by Doing.”
This is the only way you can advance the state of the art in a meaningful way in less than geologic time and with less than infinite resources. And it is why Falcon 9 already is and Starship/Super Heavy are looking to be so spectacular, while NASA’s SLS and Orion and Gateway programs are now shown to be nothing more than corporate welfare that create nothing we didn’t already have 50 years ago.
MDN, thanks for your response. I think you are essentially in agreement with my main conclusions, but you assume I am criticizing SpaceX. Perhaps my tone was inadvertently critical, but my intent was merely to explain that what I saw as an unusual design was indeed probably a consequence of the rapid prototyping process.
I am quite familiar with rapid prototyping in the software development process, where requirements are also often misunderstood, or at least incompletely expressed, but corrections are (usually) easier to make.
My only real criticism was of the opinion that the “dogleg” was the design from the start, so I went to pains to show that it was likely a result of a shaky original requirement. I second your opinion about the contributions of SpaceX when compared to the old way of doing things!
Thanks again for your response.
Ray Van Dune,
You wrote: “If a SpaceX design doesn’t look right, it’s probably because it was a mistake that could not be corrected in any other way! Thoughts?”
My first thought is that if a SpaceX design doesn’t look right then it is probably because they are doing something we didn’t expect. However, since Musk seems to have said that they were wrong about not needing a trench for Super Heavy then they probably are implementing a redesign, most likely an inexpensive or quick to implement solution, not necessarily because there are no other options.
Starship, on the other hand, is likely to land on foreign planets and moons using flat pads or bare ground. Landing on something with a trench for takeoff is unlikely to be practical, or even practicable for the first landing at each new site. Launch of Starship from the surface is likely going to require a trenchless pad, where the legs determine the distance between the engines and the ground. Missing a perfect landing by too far on a pad with a trench could result in a leg in the trench and tragic results.
I haven’t seen recent photos of the launch stand, so I can’t really give a more thoughtful response.
“But that means you now have to bolt a circular tube onto a tube cut elliptically!”
Or use an adaptor. Elliptical bolt “circle” on one side or end, circular on the other.
“I couldn’t have been the only one who wondered week after week why that elegantly modernistic Stonehenge wasn’t being touched while everywhere around it was in churn!”
Thick concrete like that takes time to set and cure.
Rod wrote: “I find it strange that they’ve decided to go almost orbital before they’ve tested the Starship at Max Q and the control conditions when transonic.”
It looks like this is their test plan. They may be more beefed up than they expect the final version to be in order to test the Max Q regime, as they should be able to afford the weight, and they may have some amount of confidence over the control in transonic conditions. The fins on Starship may present more control problems early in flight, but at transonic speed the center of mass should be far forward of the center of pressure, because so much propellant will have already been expended in the booster stage, Super Heavy.
SpaceX has been very aggressive in its Starship developmental test phase. I am becoming less surprised with how much they put into each test.
Re Max Q: it appears that the leading edges of the upper Starship fins have a “droop” similar to leading-edge flaps on an aircraft wing. The reason for this shape is probably to encourage air to flow smoothly over the upper surface of the fin at high angles of attack (AOA). At belly-flop AOAs near 90 degrees, the upper surface flow will still be turbulent. But if the nose is allowed to fall, the droop may induce a smooth flow over the forward fins while the rest of the vehicle, including the rear fins, is stalled. This would seem to be a way to improve roll, yaw, and pitch control authority of the forward fins.
But, I expect that the intent is for those fins to do nothing in Max Q regimes, and let the engines steer. If so, that leading edge droop may induce instability rather than promote stability! So I agree that never having gone to Max Q prior to doing so on top of a Super-Heavy may be a real risk. OTOH, it might just be the only way it can be done safely!
Ps. I assume AOA at Max Q will be essentially zero, or even negative.