lutorm

Exactly. In addition, by delaying the relight as long as possible you're giving drag as much time as possible to do the work for you (assuming you're not at terminal velocity, so not applicable for the ship.)

The primary purpose of having those cameras is to gather test data, not provide entertainment.

As others have said, you're correct. But one reason for doing this, beyond just looking cool, is to give a visual cue for motion. The aim isn't primarily to look realistic, but to make it as easy as possible to interpret the outputs. Motion cues help with this.

As an example, if you're watching an airshow against a clear blue sky, especially filmed with a long lens where you can't see the ground, it is very hard to understand what's actually happening because you can only see attitude changes, but not the velocity vector. Add just a few clouds in the background and the impression is very different.

Every moment your engines are burning at anything less than maximum thrust, you are wasting fuel. You want to relight as late as possible with as high thrust as possible for maximum efficiency. But that it actually works is nuts.

No. Way too hard to validate.

There is so much coal... I wouldn't worry about running out of that.

I met Lee briefly, along with a few other Nobel laureates, in 1991 at a weird symposium in Japan. Unlike some of the others, he was very friendly and relaxed. RIP.

The downfall of trains is that they require track, which require rights of way. Trains are cost-effective if a lot of people make the same trip, and that's after a massive investment cost.

No one in their right mind would fly their small airplane between two cities that were connected by high-speed rail. But if you're going from somewhere small to somewhere else small, trains will never be a cost-effective (or efficient) mode of transportation.

So you're concluding that there is no benefit to general aviation because, presumably, you don't fly?

I think we should absolutely keep airplanes as a mode of transportation, because the alternative is that all small airports go away and then it won't matter when renewable fuels become a reality because there will be no longer be anywhere to land and take off. Those airports would not come back.

Perfect is indeed the enemy of the good. So we should realize that not everyone values the same things and not single out something as deserving extinguishing just because it's something we personally don't value.

So wrong. You can get an airplane for the cost of a car. Yes, it won't be new and it won't be fancy, but you can definitely fly without being wealthy.

I take it from your attitude that you don't drive, fly commercially, buy resource-intensive consumer goods, use electricity produced from nonrenewable sources, or eat food produced from large-scale agriculture then, and agree we should make those so expensive for the average consumer that it's uneconomical to do these bad things at all?

Because otherwise your comment sounds more like hypocrisy.

How do you get seven times?

Takeoff constitutes a negligible part of the total fuel consumption. Climb to altitude uses more, but you get that back when landing since you're then using your stored potential energy.

Small-aircraft GA is a vanishingly small fraction of total fossil fuel use, and it will be quite easy to replace that with some renewable fuel solution (compared with the huge amounts of fuel consumed by transport aircraft). For my part, I think it would be a shame to kill GA because of a temporary and relatively unimportant concern.

Yes, if someone tells you how the air flows around a wing you can immediately deduce that it's producing lift, since the air is deflected downwards. The real task is explaining why the air flows the way it does.

Newton's laws are absolutely not sufficient to explain how an airfoil works.

It's not a cause and effect situation, because you can't have one without the other. A pressure differential can only exist if the flow is altered somehow, because a pressure differential means that the air molecules are subject to a net force which accelerates them. This is really just Bernoulli's theorem, which is Newton's second law. However, it doesn't tell you anything about why the flow around a wing arranges itself into such a configuration.

As a purely conceptual illustration of the fact that the air must be deflected downwards by the wing, sure. It doesn't really work, though. For example, there's no reason for the air to move faster over the top of the wing in your scenario, and without that you'd underestimate the amount of lift a wing actually generates.

Usually you draw a line from the trailing edge (which is sharp so unambiguous) to the point on the leading edge that makes the line the longest.

The definition that makes the most sense, though, is to disregard the geometry of the wing and define zero angle of attack as the zero-lift angle, because then lift is proportional to AoA.

Increasing drag is actually useful when landing. too. Trying to land an airplane with very little drag at a given spot is difficult because if you're just a little fast they'll float a long time.

There are efficiency races for general aviation aircraft, yes. Check out https://en.wikipedia.org/wiki/CAFE_Foundation

Because of the negative lift of the horisontal stabilizer, the main wing needs to provide more lift than the weight of the airplane. This increased lift requires flying the wing at higher angle of attack, which always comes with increased drag (https://en.wikipedia.org/wiki/Lift-induced_drag). Increased drag means lower efficiency.

Analyzing energy transformation is not so useful, because most drag ultimately ends up heating the air. (A little will heat the airplane skin.) There are several different mechanisms that makes that happen, and no easy way to figure out how large it is, but it's definitely not minimal. It's why (most) airplanes need an engine to stay up...

"See how it flies" that you linked is a wonderful resource for understanding the physics of aircraft and the skills needed to fly one.

Another, more math heavy treatment, of why airplanes fly that still aims to gain a conceptual understanding is "Understanding Aerodynamics" by Doug McLean: https://www.amazon.com/gp/product/B00B9QLBH0

Exactly, this is why understanding fluid dynamics is so difficult. You can't look at some physical laws and assume that the right hand side "causes" the left hand side. They all represent relations and it so happens that the fluid configuration that fulfill all the relations (and that the world adopts) is the one that causes lift. Just trying to talk about cause and effect is a misunderstanding.

Unless your two terminals are talking to the same satellite, the answer to whether your traffic has to go through a ground station depends on the topology of the space laser inter-satellite links. Whether the routing in practice allows for a terminal-to-terminal link directly without going through backhaul. I don't know. It would be a miniscule fraction of traffic.

It's worth noting that the laser links are potentially thousands of km long, so they also impose a significant link latency (even if it's lower than the corresponding fiber link.)

I think his point was that the time to check the lane over is before you initiate a lane change, not after. About the only reason to initiate a lane change without pre-checking where you're going is if there's an emergency (like the incident we're discussing) and then it's questionable whether it's better to do the lane change anyway...

YWWV. Our DRLs are not enabled if the transmission is in park.

It's worse than that, I think. The typical radar beam is so wide that it can't discriminate between in the road and near the road, so the Doppler selection is the only reason it even works at all. This is very noticeable on our car when you observe how far away laterally a car you've been following has to turn, e.g. when it takes an offramp, before the ACC ignores it.

I find adaptive cruise control definitely helps with the mental fatigue as well, because I can concentrate on looking for hazards far ahead instead of having to pay attention to keeping distance to the car ahead. But yeah, I never drive more than a few hours without taking a break anyway.

That rule explicitly states that it's not for being able to stop, though, it's just to have time to react to the driver ahead stopping. Two seconds isn't nearly enough to stop in front of a stationary object. At highway speeds it's even barely enough to not rear-end the vehicle ahead if it has to panic stop.

* ... should typically be able stop a car length per 10mph.*

This is not correct, stopping distance scales as the square of speed. The distance you'd need to stay from the vehicle in front to be able to stop if it magically came to an instantaneous stop is far, far larger than anyone will reasonably keep.

The stopping distance at 65mph, including reaction time, is at least 300ft. That's ~20 car lengths, not 6.5 that your formula would yield. If conditions are wet, your tires are not in great shape, or you're not paying attention, it's going to be much longer.