mikegarrison

When I was a kid, my dad had all kinds of funny-looking nuts and bolts in the garage. It was only years later that I realized these were aerospace fasteners. When he was getting through college, he worked at Boeing as a machinist. (He became a civil engineer, working for the Seattle Water Department.) Anyway, on his last day there, after he had gotten hired as an engineer, he had to take his toolbox home. While he was away from it, his co-workers thought it would be funny to fill it up with random fasteners and drill bits and such, as if he was trying to smuggle them out of the plant. He rolled it out to the gate, and the guard asked him what was going on. He explained he had gotten a job as an engineer, so he was taking his machinist tools home with him. The guard let him drive his truck in and helped him load it into the bed. Neither one of them knew it full of smuggled fasteners. I bet he *still* has some of those fasteners.

The video you posted explained this. This option is the only one that, from the point of view of the cabin, makes it like the door isn't there at all. It lets them use a 3-abreast seat and has a full-sized window. The other options all take up space in the cabin and require 2-abreast seating in that row. Looking for indications that a bolt was even there in the first place.

When I first joined Boeing, they had a program where engineers spent about four weeks at a voc-tech school, where we had to build various airplane parts following blueprints. This was supposed to teach us to make better blueprints. I spent my entire career in Airplane Performance (later called Flight Sciences) doing Noise and Emissions engineering. Never made a single blueprint. Anyway, it was a fun class. I still have the part I built (part of a 727 PSU) in my garage. I guess the point, if there was one, was that Hi-Locs were one of my favorite fasteners. Fun to use. Anyway I agree that, to the extent I understand the design, the bolts in question are not highly loaded and probably it made sense (or seemed to make sense) to use a castle nut just to retain the bolt, not to ensure some level of torque on the nut. Castle nuts should only be used in low-torque applications.

That's called lockwire.

Yes, two different boxes that record two different things. The CVRs are something of a compromise because pilots don't want everything they say being recorded but also understand that being able to access the CVR ultimately can help keep them safer. Many years ago, I actually used the cockpit ambient mic from a CVR to estimate the amount of hail an airplane flew through before both engines flamed out. It was of course an extremely rough estimate, but I was able to show that the plane very likely did fly through more hail than the engines were certified to be able to ingest.

They do. Sort of. Like any door, there has to be a way for it to open. For the main cabin doors, that means pulling it in a little, and then translating it a little until it fits through its own opening. With this door it works a little differently, but if it is in place then it is a plug that can't fit through its own frame. Apparently this one was not properly held in place. But that's just an assumption. There will be a final report.

But they had already flown the Saturn I, which used the third stage of the Saturn V as its second stage.

I actually sold my directly-owned Boeing stock after I retired, but still have some in my 401K. There. Now you know. So did that change anyone's lives?

I don't know what you are talking about here. SpaceX is a private company, not a public one, so they don't have public shareholders they have to make disclosures to. If you are alluding to some sort of self-dealing or other financial games, that can still be an issue with private companies. If you mean that the mostly anonymous posters on this board need to reveal if they have a financial interest in the companies being discussed, that's ridiculous. I mean, so what if they do? This isn't journalism; this is a forum for a computer game.

It's actually very difficult to tame coupled resonances like that, and mostly control systems just make sure that the engines transit through the danger zones rather than dwell there long enough for the resonance to set up.

F-1 did have a serious issue on one of the unmanned Apollo missions. They had recurring issues with "pogo" instability of the middle engine getting into resonance with the vibrational mode of the rocket structure. The fuel would slosh in the feed lines, driving a thrust instability. This would resonate with the structure that supported the middle engine. This was as much a structural issue as an engine issue. It got really bad on one mission (Apollo 6, IIRC), and would have done mission-critical damage if that had been an actual lunar attempt. They solved it for the first stage by injecting helium into the fuel system that damped the slosh. Then on Apollo 13 they had a second-stage early engine shutdown for the same reason ("pogo" of the middle engine), and they had to fix that for later missions too.

Often listed as one of the supposed great innovations from Elon Musk, but it was pretty obviously deeply flawed from the start. Same with his underground car tunnels idea. In both cases, he wants to replace mass transit that already works (rail, above or below ground) with individual vehicles. I guess so you don't have to share your personal space with strangers?

Might be just the angle the picture is taken at. But there are two test vehicles. As I understand it, it was initially designed to accommodate two engines, but when the decision was made to only use one engine, they just left it off-center. Maybe for the second one they knew that there would only be one engine, so they relocated it closer to the middle? The 3-view on wikipedia indicates that it is for vehicle #2, and it looks a lot like that second picture.

Elon Musk is not, and never was, "Tony Stark".

There are payloads that a single SLS can launch but no number of F9s can launch.

That's not the issue. I mean, rockets now have real-time computer control that allows them to land! Dealing with the thrust imbalance is not the difficulty. The concern is something like a fire or an uncontained turbo-machinery failure that sends shrapnel into the neighboring engines. We've seen in both launches now that engines start dropping out after the engines next to them drop out, which is extremely concerning.

It all depends on what *kind* of engine failure. There are many failure modes where one engine failing does not particularly risk a cascade, but there are others where it does.

Seems obvious to me that landing is still the biggest risk item for Starship/SH, but of course landing is optional (for now). But the risk item that has bothered me from the start that still seems like it my be plaguing them is the large number of engines. More engines = more redundant *unless* their failure modes are not independent. And it has always concerned me that so many engines, so close, without heavy (and space-consuming) armor between them, is a huge risk for fratricidal cascading engine failures. That means more engines = less reliability, rather than more reliability. We'll see.

My kerbals are too busy playing Baldur's Gate 3 to celebrate this year.

Yes, a year or two ago I remember standing outside my house in the cold on the rare clear winter in the Seattle area, waiting for the ISS to pass over. When it did, there was no mistaking it for anything else.

I am not saying SpaceX is going bankrupt. But that being said, the size of the company is no guarantee against going bankrupt. In fact, it can mean you do so quite quickly. Bigger company means more spending means that you can rack up debts even more quickly.

Yes, obviously if it increases the percentage chances of success, then delay or slow down the rotation. I was just reacting to the suggestion that the only reason they were doing it quickly was to show off. This (almost) can't possibly be true. The claims that were being tossed around was that the cost per flight would ultimately be lower than F9 due to a substantial increase in reusability. A claim that I found dubious. Consider, for instance, prop-fans v. high-bypass turbofans. People were predicting things like a 50% increase in efficiency from the prop-fans back in the 1980s, but it's been 40 years and the propfans are still not in service. Meanwhile the efficiency of the high-bypass turbofans has almost increased to the point where the propfans were predicted to be, so now for the prop-fans to succeed they need to be competing against the current turbofans, not those of the 1980s. As F9 gets more and more reusable and cheaper and cheaper to fly, SH has to compete against the newer, better F9 costs, not the F9 costs that existed when SH was conceived.

There is no "typical rocket of this size". Every second before they boost back makes it harder to return to landing, and the whole premise of the booster is that it must return to landing.

Water deluge has been used for 50 years, at least. The question is not "how did SpaceX design a water deluge system so quickly?", but rather "why did they think they didn't need one before?"

I assume he was confusing km/s with km/h.