There are some nuances to it. British Airways (not the original British Airways Ltd [0], who merged to form BOAC) was established to manage several existing airlines that had already been nationalised (BOAC, BEA) and two regional carriers (Cambrian Airways and Northeast Airlines).
Of course BOAC and BEA had been made my consolidations of many smaller airlines which gets messy quickly when tracing the lineage. Even Cambrian and Northeast had formed British Air Services prior to this which was 70% owned by BEA.
So it is technically true that is was started as a state owned airline, but one made from companies that were originally created as private with a mixed history of state ownership.
You may be thinking of a different film, as all the cast members listed on wikipedia[0] are stated to have died after 1945.
The trivia section of the German wiki page of the same film says there's a disputed rumour that the film was prolonged to help the young extras avoid conscription.
I said a good overview. Many experts have given their analysis on why Lynetteholmen sucks including environmental scientists [1]. The very fact that the environmental assessments were done piecemeal [2] plainly demonstrates the politicians responsible for this mega-project disaster knew exactly how bad it was.
The second route is currently being built in Munich [0], with work started in 2017. I recently watched a youtube video by The B1M about rail projects in Germany that included a long section about the currently ongoing works in Munich [1] that gives a good visual overview.
If it takes energy to compress the air in the cylinder - doesn't it also release most of that energy when that compressed air is expanded on the subsequent stroke?
If you release the compressed air without pushing the cylinder down you would lose that energy, but you would need a extra device to do so (by lifting a valve at the right time). This option does exist for large vehicles like trucks as a compression release engine brake [0], but this isn't something you'd have on a family car.
In a petrol engine you always want the same ratio of petrol to air in the mix that is taken into a cylinder. As you want to vary the amount of fuel, and therefore power developed, you have to be able to therefore limit the amount of air that is sucked in. Otherwise the engine would always run at full power.
There is a mechanical restrictor called a throttle plate that lives inside the throttle body that restricts how much air the cylinder can pull in (and therefore how much fuel is injected to get the same fuel/air mix). This is controlled by the throttle. When you are coasting, this plate is in its most closed position. This creates significant resistance on the intake stroke, and is where the majority of energy is lost during engine braking. This is also known as a pumping loss.
Diesels always intake the same amount of air, so they can compress it enough to autoignite the fuel. They vary the amount of fuel injected to the same volume of air. This means no throttle body or plate, so unless an extra exhaust restrictor has been added there is minimal engine braking on a diesel engine.
You're right. Petrol engines are air pumps so I should've realised the explanation wasn't correct.
Though the ECU would be doing the AFR management on modern EFI engines as the injectors aren't vacuum operated like Carburetors were. You should be able to cut fuel injection when coasting in a modern engine, can't run lean if there's no fuel at all. Not sure if carbs could do the same.
On all the fuel injected engines I have owned there is a physical cable that controls the position of the throttle plate. There is an airflow mass sensor the other side of the plate to measure the amount of air and therefore how much fuel needs to be injected. So interestingly in these sort of engines you're really just controlling airflow to the engine rather than fuel/air mix like on one with a carburettor.
More modern engines have electronically controlled throttle plates, and this is definitely somewhere you could do something clever like you suggest - cutting fuel flow but also maximising airflow when there is zero throttle input.
I assume engine braking is generally considered a beneficial thing by manufacturers, but it could be fun to be able to customise the amount. Or do something like have the braking come on gently at first then harder. Maybe even try and have a linear or flat response curve vs. engine rpm.
> cutting fuel flow but also maximising airflow when there is zero throttle input
You don't want to do this. Much of the engine braking effect is from pulling the intake air charge past the mostly closed throttle plate. On a car with a wide open throttle plate [even with no fuel], the engine is acting more like a spring than a damper. On the intake stroke, it will pull an intake air charge past the small restriction of the open intake valve(s), then compress it on the compression stroke, then release that compressed energy on the "power" stroke, then exhaust it past the small restriction of the open exhaust valves. Pushing air past the valves will cost energy, but it's not much.
This is why diesel trucks' engine braking works differently. (Diesels don't have a throttle plate.) They can open the exhaust valves to prevent the energy recovery in the "power" stroke to create a higher net braking force. Jake Brake: https://en.wikipedia.org/wiki/Compression_release_engine_bra...
> Or do something like have the braking come on gently at first then harder.
You can do this by letting go of gas pedal slowly. I have "current amount of fuel used" info in my car (liters/100km), it shows pretty clearly, that when going fast and slowly letting go of gas, amount of fuels slowly goes to 0. If I let go of gas fast, the engine is intelligent enough to not close throttle as fast as possible, still probably takes 1 second.
> More modern engines have electronically controlled throttle plates, and this is definitely somewhere you could do something clever like you suggest - cutting fuel flow but also maximising airflow when there is zero throttle input.
They cut fuel flow and close throttle plate almost completely but still allow some small amount of air, in order to actually do engine braking. If you need to coast, you can apply clutch in manual. Don't know that much about automatic, but from what I've driven, they use "lift gas" as a "engine braking" signal, so probably they can't really coast that good.
I've got both at the moment on my two Hondas. Both manual, one with a throttle cable and one with throttle-by-wire. There's quite a bit of difference in how they handle off throttle. The cable will just slam the throttle shut if you just jump off the pedal (obviously) and it jerks pretty hard. The throttle-by-wire car hangs the throttle a little when letting off and doesn't just immediately start decelerating. Then it's much smoother once it does start slowing down. The ECU definitely doing something to smooth it out.
Funny because the cars build dates are only 2 years apart, 2005 and 2007, and they're both K20 engines but the engines handle so different.
The ECU is doing that because rapid changes in state are bad for emissions. Letting you just slam the throttle closed could result in a tiny, but measurable at OEM scale, amount of extra fuel going half burnt out the tailpipe. Slamming it open can cause too lean combustion and oxide byproducts which.
The OEMs try real hard to prevent this because the amounts of emissions byproducts that aren't water or C02 they're allowed to produce are on the order of single digit grams per multiple miles (you can mentally file it as "about the baseline air quality in urban areas" though the rules are hugely more complex than that) so these edge cases matter.
An idling I4 has about 10 injection cycles per second. And the ECU clocks injection time corrections at least at that rate, more likely at double that rate or more. So I think that the smoothing is mostly there for the owner's wellbeing, not emissions.
Curiously I have the opposite problem with Too Good To Go - they never give me notifications of available things I might be interested in, even though I've set that I want them.
This is on Android though, so perhaps an ecosystem difference?
> More people are alive today than have ever lived.
Assuming you meant died instead of lived to avoid a potentially nonsensical reading, this is not true.
It seems this factoid[0] has been around since the 1970s, and at least in 2007 it was estimated to be 6% of people who'd ever lived being currently alive [1]
[0] In the original sense of factoid - being fact-like, but not a fact (i.e. not true). C.f. android, like a man
You are absolutely correct about autorotation and helicopters not falling out of the sky. There is one nuance that the rotor blades still need to be able to rotate for this, and a failed gearbox can prevent that. Anecdotally that feels like the most common cause when I read about another crash in the North Sea.
Not all boots are made the same though. I had some bad luck with a pair of veldtschoen welted boots from the English firm Crockett and Jones in a custom leather. The commando sole split twice at the toe, which they repaired, but after less than five years of wear the lining at the heel had worn through.
I took them in to be rebuilt, but after inspection they said the stiffener had come loose, and nothing could be done. Here have your expensive and now broken boots back.
I'd assumed when I got them I'd be wearing them for decades, and at least a few rebuilds. Maybe there was something wrong with that specific pair, but I did have a goodyear welted sole randomly detach from a pair of six month old city shoes from the same firm. And yes I had been looking after my shoes (frequent cleaning and polishing, always using shoe trees, skipping days between wears, etc).
When I had a pair of Church's fall apart I put that down to them no-longer being a quality brand, but now I don't think you can guarantee a long life just as the shoe was expensive and from a reputable brand. I have many shoes that have lasted better (and now since covid I don't wear polished shoes daily), but that does sometimes feel like luck of the draw.
Some SLBMs (Submarine Launched Ballistic Missiles) use star sighting to correct their trajectory mid-flight. ICBMs launched from silos know exactly where they're starting from, whereas a submarine is both moving, at different depths and has some error to knowing exactly where it is. Missiles use inertial guidance, so knowing your starting your point is crucial.
How accurate a missile needs to be is a whole other dimension though. If the value of a missile is as retaliation to destroy a city (countervalue) then it can be a large warhead and "miss" by quite a margin but needs some form of credible survivability of an enemy first strike. If the missile is to be used to destroy enemy military installations (counterforce) then it needs to be a lot more accurate but usually the implication is as a first strike so less survivability is required.
When you have nuclear weapons that you can drop from manned aircraft, ICBMs from silos and SLBMs controlled by different military branches there is going to be a lot of politics over what the missile is for, which will determine its required accuracy, which will be a factor on if it needs star sighting.
Of course BOAC and BEA had been made my consolidations of many smaller airlines which gets messy quickly when tracing the lineage. Even Cambrian and Northeast had formed British Air Services prior to this which was 70% owned by BEA.
So it is technically true that is was started as a state owned airline, but one made from companies that were originally created as private with a mixed history of state ownership.
[0] https://en.wikipedia.org/wiki/British_Airways_Ltd