I suspect he doesn't know about - or thinks most people don't know about - ad blockers, and so offering a browser that has more relevant ads will attract people who hate the irrelevant ads but figure they're unavoidable.
Obviously, for those of us who are smart about adblocking, who almost never see ads we don't agree to see, it's stupid.
But shockingly, there are probably plenty of people who will happily sign up for that "improved" experience.
Not surprising - given the accident description, the pilots dramatically exceeded the structural limits of the airplane by dramatically exceeding the posted limits of safe operation.
Here's the report of the event:
https://ancillary-proxy.atarimworker.io?url=https%3A%2F%2Fasn.flightsafety.org%2Fa...
It reads to me as if the (co)pilot deliberately amplified the Dutch roll motion (which is a simple lateral/directional dynamic characteristic of aerodynamics of ALL aircraft, whether or not it's operationally significant) until reaching such a large motion (probably a combination of simultaneous roll and yaw rate) that it exceeded the strength of the engine pylons.
In particular, it's possible to overstress the aircraft by putting in large OPPOSING inputs in an attempt to stop to the Dutch roll motion too quickly. It's quite possible that if they'd simply gone hands/feet off the controls, it would have damped out naturally with no damage. The failure of AA587 is an example of this: the pilot's large rudder input against the yaw motion (which was due to a yaw excursion due to unexpected turbulence) is exactly what caused the tail to snap.
Nearly every claim in this post is factually wrong. This person apparently knows nearly nothing about aircraft flying characteristics, other than buzzwords.
I am a degreed aerospace engineer working in flight test for over 30 years and I have tested large commercial/passenger-class aircraft, including deliberately-induced Dutch rolls for test purposes. I have sat in the cockpit behind pilots executing these Dutch roll maneuvers intentionally. I personally joined a flight test team that had a crash a few years before, due to a Dutch roll event during flight test in the early 1990s. I also edited the US Naval Test Pilot School handbook FTM-103 "Fixed-Wing Stability and Control Theory and Flight Test Techniques" in 2019-2021. So I'm working with definitive expertise acknowledged in my field.
Some facts.
1) The proper term is "Dutch roll", uppercase, not lowercase, just like "American flag" not "american flag."
2) Dutch roll has absolutely NOTHING to do with the wings alternately stalling. Zero. Nada. Its cause is more subtle and would take a few pages to explain; go look up section 5.2.2.3 of the USNTPS FTM-103 flight test manual (which I edited) if you want the math. A wing stall MIGHT occur AS A RESULT of Dutch roll if you cause such a very large Dutch roll at a very low speed, but I've never seen that happen in hundreds of flight test events, some of which were done with me in the airplane. And even if the wing DOES stall, it's not a big deal most of the time; I've also done many stall tests. We're careful and we know what will happen, but most stalls are immediately recoverable (because all airplanes are carefully designed to recover quickly and gracefully from an inadvertent stall).
3) There is no "triplet" input to "get out of" Dutch roll. It is a natural oscillatory motion and will persist until a "yaw damper" is engaged to counter it automatically; it's almost impossible to manually damp out because it will simply recur naturally. Even if you put in a complicated input to damp it out, it'll start again just due to small gusts. No pilot wants to spend all their time fighting Dutch roll; that's why aircraft have yaw damping systems.
4) Dutch roll absolutely CAN shear off the vertical tail if it becomes large enough. Look up the crash of American Airlines AA587 in 2001. And I personally worked on a program that crashed a Navy S-3B test airplane in 1991 from Dutch roll testing when the vertical tail failed due to bad test technique (deliberately overdriving the Dutch roll mode beyond the limits of the vertical tail strength, due to miscalculation of the tail strength limits). I personally have on my desk the control stick that was recovered by wreckage divers from the bottom of the Chesapeake Bay to remind me of that failure. That crash still informs Navy flight testing practices today.
5) But in normal operation with a properly-functioning control system and absent extreme pilot inputs, Dutch roll will never become large enough to cause a failure; all aircraft are designed with sufficient stability to not reach this point without a control system input (either deliberate or due to a hardover rudder input). It is, however often a nuisance residual motion which can be annoying or nauseating.
6) Dutch rolls not exactly a "very slow" oscillation. Slow, but not VERY slow. In most large aircraft, its period is about 5-6 seconds per cycle. Smaller aircraft have faster oscillations, maybe 2-3 seconds. It's easy to observe, and quite annoying.
See my root-level post here with more information about Dutch roll in general, and the actual issues in this event.
I have a few observations about this incident, because I see some false information in this thread.
I am a degreed aerospace engineer working in flight test for over 30 years and I have tested large commercial/passenger-class aircraft, including deliberately-induced Dutch rolls for test purposes. I have sat in the cockpit behind pilots executing these Dutch roll maneuvers intentionally. I also edited the US Naval Test Pilot School handbook FTM-103 "Fixed-Wing Stability and Control Theory and Flight Test Techniques" in 2019-2021. So I'm working with definitive expertise acknowledged in my field.
Some facts.
First, the proper term is "Dutch roll", uppercase not lowercase, just like "American flag" not "american flag." Basic respect for Holland and all that.
Dutch roll, according to the US Naval Test Pilot School handbook FTM-103 "Fixed-Wing Stability and Control Theory and Flight Test Techniques", is defined as a second-order oscillatory lateral/directional mode of oscillation, sometimes referred to as a nuisance or annoyance motion. It is characterized by an oscillation back and forth between roll and yaw (sideslip); if you look out the side of the aircraft you'll see the wingtip trace a small circle or oval path. Nearly every airplane will exhibit Dutch roll - it's baked into the aerodynamics - the only question being how susceptible it is, and how well it naturally is damped.
So every airplane ever flown is deliberately tested for lateral/directional stability including deliberately inducing Dutch roll to check for its damping characteristics: will it naturally die out or is the "yaw damper" needed to reduce it, and how fast is it reduced by that system.
Dutch roll testing is actually one of the more benign types of flight tests. We are careful to avoid exceeding the sideslip limit of the airplane, so we build up to the larger test points, but it's generally quite safe.
You can see a sample plot of relatively representative Dutch roll motion here: https://ancillary-proxy.atarimworker.io?url=https%3A%2F%2Fwww.researchgate.net%2Fp...
My read of the article and other information I can find about this incident is that it wasn't a Dutch roll that *caused* the problem. "Dutch roll" is simply a natural mode of oscillation present in any airplane, and won't lead to any aircraft damage unless something else went badly wrong. In this incident, it's likely that the rudder power control unit (PCU) had a "hardover" or oscillatory failure and drove the tail to swing sideways (either once or oscillatory) far enough to cause physical damage to the tail (the FAA preliminary report says "substantial" damage), which I presume manifested as popped rivets and visible sheet metal buckling (I've personally seen these before after flight test events that went a bit too far). So the failure was not Dutch roll itself. Presumably the pilots immediately turned off the Dutch roll damping system (the "yaw damper") and maybe even the rudder PCU itself. The resulting residual motion after such a failure, without the yaw damper reducing the oscillation, might be characterized by a sustained yaw/roll oscillation which WOULD be a Dutch roll mode of oscillation, but that was the effect, NOT the cause.
Dutch roll is not inherently dangerous. What *is* dangerous is when it is excited (by pilot input, by control system failure, or by wind gusts) and becomes large enough to cause structural damage, usually to the vertical tail due to side loads on the tail. The crash of American Airlines AA587 in 2001 is an example of what happens when the vertical tail fails due to overstress; the pilot encountered an wind-gust disturbance and used too much rudder to try to correct the motion, and literally sheared off the vertical tail. So modern aircraft include rudder limiting systems to prevent large inputs at high speeds.
In this incident this week, the rudder PCU apparently malfunctioned and caused a huge yaw input, leading to (probably) vertical tail damage.
AFTER the real failure and any damage that occurred, because of the failure of the PCU, it's likely that the rudder couldn't properly damp the Dutch roll during the rest of the flight, so there would also have been a sustained but small oscillation which can cause people to get nauseous or worse due to motion sickness.
If you want to learn more about Dutch roll, here is an older public-domain copy of FTM-103 (the new version I edited is not being released publicly) and you'll find the relevant information in section 5.2.2.2.3.
https://ancillary-proxy.atarimworker.io?url=https%3A%2F%2Fusntpsalumni.wildapric...
Finally, is this a symptom of Boeing design = bad? No, I don't think so. Every aircraft has a ton of parts which must be well maintained. Servos (PCUs) fail due to wear and tear. Aircraft maintenance practices are designed to spot failing or worn parts such as PCUs and replace them before this happens, but sometimes it still happens. That has nothing to do with the fundamental design. And as I have tried to convey above, Dutch roll is inherent to every airplane. The only question is how good are the systems to limit and damp it out, and how good is the servo design to not cause it. Since this and thousands of other 737 aircraft generally have no problems like this, it's not a design flaw; it's a worn-out-parts flaw. So if anything, I'd pin this as most likely due to maintenance not catching a worn part, but maybe just bad luck.
The CO2 emissions required to launch 2.5 megatons of hardware into deep space will be enormous. I doubt that much fuel exists on Earth but let's think about the math.
Let's do a back of the envelope calculation...
The Falcon Heavy (FH) is probably the most efficient launch vehicle today. It can launch about 44,000 lb into a Mars transfer orbit. That's a fair approximation for a Lagrange point orbit.
At FH scales, launching 250 megatons into deep space would require 114 million FH launches, expending 772 TRILLION, or 0.772 quadrillion pounds of fuel.
The FH requires 3,400 tons of propellant for each launch, or about 7 million lb. Each FH launch puts about 2 million lb of CO2 into the atmosphere. So all those FH launches would put something approaching 200 TRILLION pounds of CO2 into the atmosphere. That's 0.2 quadrillion pounds. The earth's atmosphere is estimated to mass about 5.5 quadrillion tons, or 11,000 quadrillion pounds. To launch all those rockets would increase the CO2 concentration by 0.18ppm just from the fuel burn.
The atmosphere is about 0.00017% methane, about 2.4% of the amount needed to launch the rockets. It's arguable that converting that methane to CO2 would reduce global warming (methane is 82X more potent a greenhouse gas than CO2), but obviously it's not enough to fuel the rockets in any case. It also doesn't account for the energy expended to extract that methane. I couldn't find any data on how much methane is available from other sources, and clearly the vast majority of the fuel would not be from the atmospheric methane, thus producing an overall net increase in warming.
This analysis doesn't even begin to address the CO2 emissions related to producing 114 million (even partly reusable) rockets, including extracting all the raw materials needed to build them.
Please do check my math, but this seems like a ludicrous proposal. Even if (as suggested in the article) we strip an asteroid for much of the materials and the lifted mass, it's still quite an ask on the global economy and climate.
Maybe instead we figure out how to reduce emissions instead?
I even wonder if they deliberately used the self-destruct to prove to the FAA that THAT particular issue was well-and-truly resolved.
They can be animated USING a very powerful (4090) workstation, BASED ON an iPhone video and stills. The iPhone won't do the animation. There's a HUGE distinction.
Replying to myself: one of the replies to my post indicated that someone spotted flaps underneath the thrust-producing grid. That makes sense - you could set up an arrangement that would use actuated flaps (little servo motors would be sufficient) to block or open part of the thrust produced by the grid, providing a fairly fast and effective rolling or pitching or even yawing moment. That would probably be much better than modulating the thrust in real time. It does come with the tradeoffs of weight and complexity: servos, flaps, wires, etc.: many extra bits that you don't need with a simple quadcopter.
But it wouldn't solve the issue of a widely distributed thrust, and the voltage requirements. And it's frustratingly pedestrian: just a giant ionic box fan, instead of a large propeller, that does basically the same exact thing as a simple fan, just (maybe) more efficiently.
Add to that something I didn't think of before: if you lose some grids, there's NOT a lot of redundancy to keep control.
With all that I wrote above, even with controllability solved by such methods as vane-based thrust deflection, I'm still very skeptical that this thing will work at any cargo-carrying scale.
Just a few quick observations from a flight test engineer.
There are no "innovative physics" here, unlike what the company website claims. It's pretty rudimentary physics, actually, that's been well-known for a long time. Maybe there are some new tricks at scaling it up, but there's nothing fundamentally different at play here.
Battery life could be a real problem. The literature is somewhat mixed on efficiency, with some claiming much higher efficiency than jet propulsion.
https://ancillary-proxy.atarimworker.io?url=https%3A%2F%2Fwww.sciencedaily.com%2Fr...
But this kind of propulsion requires VERY high voltage source. Getting high voltage out of low voltage power cells requires converting DC voltage to higher levels, which itself has significant inefficiencies. No matter how many low-voltage batteries they use, they'll still need significant conversions up to the 10s or 100s of kilovolts needed to generate ionic flow.
However, the most significant compromise, in my view, seems to be the low thrust spread across a huge area, which seems to lead to controllability problems. A jet engine or propeller system has fairly small exit areas with high air velocity; this instead requires a fairly large cross section for the lower-velocity thrust exit area. This results in a fairly large platform, but with low thrust spread across its surface. When you get into the physics, or more specifically the mass dynamics, the problem is a large moment of inertia with a low force to control it.
Imagine, if you will, a rod about five feet long, with a bowling ball at the center (the mass of the system, mainly the batteries and cargo in this case). And there are small thrusters way out at the tips of the rod (like one axis of a quadcopter). You can easily imagine it doesn't take much force on the tips of the rod to make that system rotate. All the mass is at the center. But now imagine the bowling ball mass and the thrust force spread out along the entire length of the rod. If you want to quickly affect the angle of that system, you need a fairly large force differential between the two sides, and it's going to take a while for that force to have an effect. So it is with this system: the mass is spread across a very wide area, and so is the force. Even if the batteries and cargo sit at the middle, you've still got the large structure to hold the thrust components, and the thrust is not concentrated out at the tips where it would have the most effect. At best it can be imagined as effectively only halfway out to the tips.
I'm also worried about response time. Any system like this inherently uses the thrust to create control forces. Now, the real beauty of a propeller-based drone driven by electric motors is the almost instantaneous thrust response, which is why a typical quad or hex copter can be absolutely rock-steady in the air, even with turbulence. (This is also a reason why you don't see jet-engine-based quadcopters: jet thrust is very slow-responding.) But when your thrust response is spread across square meters at very low local airflow speeds, and depends on voltage changes to induce nearly undetectable airflow changes, response time suffers significantly. When you slow down the response time of your control system, you lower the dynamic stability of the system. And the stability decreases with gain in any system - the harder or faster you try to maneuver, the lower the stability.
So from my perspective, there are two inherent challenges that will lead to control problems: a hugely distributed thrust area, plus slow response time. The result, as you can easily see in the video, is instability. The thing never ever stops rocking back and forth, and when they get close to touchdown the amplitude of the oscillation increases noticeably. And that was with a basically zero-load condition. Size this thing up to carry cargo, and it will only get worse. You can try to filter it, but that just leads to larger errors and overshoots in desired position or angle. You can't have stability AND accuracy with a slow-responding or low-force system; you can only pick one.
Another significant problem with very large cross sectional area for generating thrust is drag issues - sure, you can generate a lot of thrust, but using it to move air across those large surfaces means you have a very large surface to generate drag against that airflow. So moving that massive structure through the air (the goal of most aircraft, after all, is moving between locations) comes with a huge drag penalty. If the thrust efficiency gains estimated in that article come to pass, perhaps it won't matter, but I'm skeptical at the moment.
So I'm not holding my breath for success of this thing. Neat toy, and neat demo, but I don't expect the fundamental physics problems to be solved any time soon.
The catch WAS successful, as much as it needed to be. Yes, they had to then drop it because of helicopter sling load dynamics, not because they couldn't catch it.
It didn't work just like the first few Falcon 9 landings didn't work. Baby steps, sometimes.
> Nothing justifies the taking of innocent life, including your own. I get it if you want to disagree, but I firmly believe this is and will always be evil.
The very religious philosophy that teaches about the sanctity of life and about evil also teaches that nobody is innocent. You seem to be mixing up your doctrine here.
Note: I'm a Christian and I'm generally opposed to euthanasia myself - but this argument doesn't seem self-consistent.
Every lawyer, and many retired police officers, will tell you never to agree to talk to the police, at least without a lawyer present, on the premise that you always can be found to be doing something wrong if you give any investigator enough words to convict you. In fact for most people it doesnâ(TM)t take that much before you will inadvertently admit to doing something criminal. In much the same way, even if you think youâ(TM)re a law-abiding citizen, the chances are nearly 100% that something on your phone is illegal in some way. You just donâ(TM)t know what that something is, so the only wise course of action is to never give law enforcement any voluntary access to your device.
What many people miss about this study is that it was done "in vitro," in a lab setting in a cell culture. That's a lot different than "in vivo," in the human body. And this study even points out that fact.
Well, a lot of things will kill viruses in vitro. Bleach works really well, for example. But you don't want people drinking bleach to kill COVID.
Oh, wait....
The actual paper does show quite a few very good examples.
https://ancillary-proxy.atarimworker.io?url=https%3A%2F%2Farxiv.org%2Fpdf%2F2104.076...
We are drowning in information but starved for knowledge. -- John Naisbitt, Megatrends
