Help! Buster has busted.

As a Royal Navy helicopter pilot for many years and with two years teaching helicopter aerodynamics to student pilots I am probably qualified to comment here. ;-)

Given that a helicopter is a three dimensional craft, the Cyclic (that’s the stick between the legs) controls the general movement of the craft by controlling the main rotor. It’s called that because it controls the pitch of the rotor blades independently of the rotor position, that is to say that each rotor will be at a required angle at a given part of its rotation. As the rotor turns, it’s angle will change. The effect of this is to control the direction in which the helicopter moves. The other rotor control is beside the pilot and looks like a handbrake. It is called the Collective because it controls the pitch/angle of all of the rotors together. The effect of this is to vary the amount of lift generated by the rotors to control the up and down movement. So a typical take off would be to pull up the Collective (more pitch, go up) and once up a bit to push forward on the Cyclic (adjust the pitch at certain points to cause the craft to move forwards).

So far, that is a pretty good summary. It would be unfair to carp about details.

There is also a Throttle, but unlike a car a helicopter is designed to run at a fairly steady engine speed and blade rotation. Flight speed is controlled by how much Cyclic is applied, and height is controlled by how much Collective is applied, not by making the engine go faster.

Very few helicopters have had hand throttles for half a century. I learned on one that did, but the perils of getting the rotor speed wrong have been much alleviated by automatic systems.

And finally there are two pedals for the rudder. This works by adjusting the speed of the tail rotor. The tail rotor counteracts the gyro effect of the main rotor in a carefully balanced system. By increasing or decreasing the speed of the tail rotor you can turn the body of the helicopter to the left or right.

I am afraid that is so wrong, and it is the reason I am replying. ;-(

I will excuse the misuse of ‘rudder’ as it might give the right idea, but the speed of the tail rotor is constant, since it is directly connected to the main rotor. The pedals adjust the collective pitch of the tail rotor blades to change its thrust. It is the ‘torque reaction’ of the drive to the main rotor that this thrust is balancing, and has nothing to do with gyros. Small adjustments to that thrust will turn the body of the helicopter.

And yes, a tail rotor failure means that the system will try to balance itself by having the main rotors and craft body spinning in opposition. When the rotors are what’s keeping you up, consider it a “uncontrolled fall out of the sky” event

If the torque reaction is not balanced by tail rotor thrust it will turn the body of the helicopter in the opposite direction to the rotor. That might be a disaster, but not necessarily. In forward flight the tail boom and fin provide lateral forces and if quick, a pilot can lower the collective, reducing the torque to zero. The helicopter will descend, but under control in a condition called autorotation, from which a safe landing can be made.

This is Aldershot, so I hope this diversion is acceptible. ;-)

Very few helicopters have had hand throttles for half a century.

You must have found Airwolf to be somewhat amusing, all the “crank up the epic looking throttle to go faster” stuff. And we’ll just gloss over the aerodynamic issues of going even faster by the use of rocket thrusters. ;-)

I am afraid that is so wrong, and it is the reason I am replying. ;-(

That’s okay. I basically learned this stuff in a book¹ that didn’t go into much detail about the behaviour of the tail rotor, other than “if it fails you’re screwed”. I did wonder how it would change speed, maybe some sort of slip clutch arrangement? But after your explanation, variable pitch there is a lot simpler.

and has nothing to do with gyros

I didn’t say gyros, I said gyro effect. That being that a thing with a part that is spinning will have a natural inclination for itself to start to spin (that’s why if you have a fancy gyroscope toy in a little metal cage, setting the flywheel part spinning will cause the cage to spin as well). It’s this that the tail is counteracting.

The helicopter will descend, but under control in a condition called autorotation

This is where your Royal Navy background is coming out. I bet one needs balls of steel to pull that off…
How do you even train for such things?

¹ And two minutes flying a Westland Lynx (with the training wheels on²).

² Direct quote of the proper pilot. Apparently they’re “interesting” to fly with the stabilisers off. He didn’t demonstrate.

You must have found Airwolf to be somewhat amusing, all the “crank up the epic looking throttle to go faster” stuff.

I go further back to Whirlybirds. ;-) Even today you will hear the sound effect on film of the rotor increasing in speed as a helicopter climbs away. It sounds like a car would, so it must be right.

And we’ll just gloss over the aerodynamic issues of going even faster by the use of rocket thrusters. ;-)

That is not so ridiculous in principle. Additional forward thrust offloads the main rotor allowing it to remain aerodynamic at higher speeds. But Airwolf was just daft.

I didn’t say gyros, I said gyro effect.

It still has nothing whatever to do with gyro effect. It is all to do with torque reaction. You will come across people, some of whom should know better, trying to explain rotor dynamics in terms of gyros. They are wrong, wrong wrong.

setting the flywheel part spinning will cause the cage to spin as well

Putting on my physics teacher’s hat, that too is not the gyroscopic effect. With good bearings the gyroscopic effect only happens when an attempt is made to change the direction of the spin axis. It then turns at right angles to both the spin and applied turn.

I bet one needs balls of steel to pull that [autorotation] off… How do you even train for such things?

You train at autorotations very reqularly and full engine off landings often. It is a bit like gliding. Doing it without a tail rotor is not something you train for, but might think quite hard about. ;-)

Edit. Pilots today do a lot of simulator training and might be faced with a tail rotor failure emergency.

Old operating systems could fit in a 16K ROM. Modern ones take megabytes for the basic core, and potentially gigabytes for a full install.

This wasn’t my point. I’m just saying that a complex OS must stay simple to use.

Example: archives. There is the case where it adds complexity (different way to manage them, compare to directories). And there is the case that add them without adding complexity: ArcFS, SparkFS, etc. And sometimes there is a third case: no functionality added, but more complexity. See Gnome3 VS Gnome2.

As you can see, little in common with a car, never mind a bicycle.

Wasn’t my point too. I wanted to say that if you wan’t to learn to go from point A to point B, it’s easier to begin with simple solutions (by foot, with a bicycle) before learning to drive a space shuttle. Even if the space shuttle is best way to go far away.

Python is popular because it isn’t hard to learn the basics and you can do a lot without too much code or weird syntax rules

Correct. Was my point. Simple is sometimes good.

Some people still asking why C is so popular, compared to other languages. The limited size of the base framework is important. Of course, it’s fantastic to have a framework that can do everything. But for a newcomer, thousand of pages of docs is a no go.

HTTPLib I’m ignoring, it’s a Python library as far as Google tells me.

No, a RISC OS one :)

This wasn’t my point. I’m just saying that a complex OS must stay simple to use.

My mistake, I thought we were talking about the level of complexity in OS libraries.

Yes, generally speaking operating systems nowadays are quite a bit easier than in the past. There are many imperfections, but “stuff plugs in” without all the hassle of fiddling with IRQs and the like in days gone by.
Press the power button, the OS starts up, gives you a nice clicky-pointy interface so you can start up Firefox and watch kittens on YouTube.
Which is a far cry from starting the computer from a boot disc, tweaking CONFIG.SYS and AUTOEXEC.BAT to get the most memory, then finding and running a program.

Okay, the memory tweaking might have been a one-off, but you needed to know about HIMEM.SYS, LOADHIGH, and the fact that some things liked to be loaded in a specific order and/or not loaded high. All problems that nobody needs to care about these days. Tell me, how many people using modern PCs have any idea what A20 is? [ https://en.wikipedia.org/wiki/A20_line ]

I wanted to say that if you wan’t to learn to go from point A to point B, it’s easier to begin with simple solutions

I disagree. One must go with appropriate solutions. By all means favour simplicity over complexity, but go with what is most appropriate.

Some people still asking why C is so popular, compared to other languages.

Because it is well known, widely supported, and is often used for operating system components?

Useful, also, to distinguish between interpreted languages and compiled languages. They each have their strengths, even though there is some overlap.

But for a newcomer, thousand of pages of docs is a no go.

C has just as many (if not more) libraries and frameworks available. They usually aren’t part of the base compiler installation, but can be added.
But, then, PHP supports the use of modules that extend its capabilities with features such as image reading/writing, plotting text into images, talking to various types of database, etc etc.
One does not need to learn about the peculiarities of DBMS in order to write “Hello World!” in PHP. The thousand-pages book is because in order to sell copies, it has to document everything that a user might want to know.

No, a RISC OS one :)

Ah, Chris Mahoney’s one. I didn’t use that as, well, it wasn’t that hard to use the URL module directly. The only quirk is that initiating the fetch doesn’t actually do anything, that part happens when you loop waiting for something to happen. :-)
Oh, and don’t run test code that tries to talk to WebJames on localhost in a command window, it needs to be a task window so the multitasking still works, or WebJames ain’t gonna reply! :-) :-)

I note (brief look at the source) that httplib doesn’t appear to set the “Host:” header (does URL do this automagically?) and it doesn’t look as if it can handle redirections … though, arguably, URL ought to do this for itself before people devise a dozen different ways of doing the same.

Simple is sometimes good.

Sometimes – the key word there. Thoughts and methods change over time. When processors were slow and expensive, clever hardware was important. But that’s no longer the case, a little microcontroller can run rings around any amount of cool hardware – that’s why today’s washing machines have electronics inside rather than the nifty mechanical things that came before. Plus the tech adds extra possibilities like sensing the amount of washing present to vary the water level specific to what is being washed.
Once it was simple electrics and complex mechanics. Now it’s simple mechanics and complex software.

And in the future? Who knows… Maybe I’ll win the lottery and have somebody else worry about that. Maybe Iran and UK will go to war, blow the crap out of everything, and we’ll be back to using those old rustic lavoirs?
I suppose both options count as simplifications. ;-)

Helicopters: I was always amused that the RAF lumped helicopters and hovercraft into the same “things that can’t glide” book.

Mind you, I’m so old I had to sit on the parachute when I learned to fly.

I note (brief look at the source) that httplib doesn’t appear to set the “Host:” header (does URL do this automagically?)

I’m pretty sure that AcornHTTP (which is called by URL) does this, although I’m at work right now so can’t check.

and it doesn’t look as if it can handle redirections … though, arguably, URL ought to do this for itself before people devise a dozen different ways of doing the same.

Agreed. It’s on my to-do list to put it in AcornHTTP, but given my backlog don’t expect it any time soon!

My mistake, I thought we were talking about the level of complexity in OS libraries.

True too, but that’s another subject. Libraries are here for modularity, but tend to become towers of babel… sometimes used only by 1 application.

I disagree. One must go with appropriate solutions.

Yes, but there are steps to follow too. IT programming is the only domain where it seems to be a problem.

And in the future? Who knows…

For IBM, in four years it will be brain like computing, with analog tech. It’s even not a joke.

Python is popular because it isn’t hard to learn the basics and you can do a lot without too much code or weird syntax rules.

I suppose you know Python has “made it” when it turns up in college-style calculators. Complete, I should add, with code colourisation, judging by the photos.

Original size: https://i.imgur.com/oDvk8q5.jpg

What I don’t quite understand is why somebody would pay €75 for a “clever” calculator that offers a miniscule display and… I’m not even sure I want to contemplate how to enter code on such a device. Plus, I bet the processor is none too impressive either.

For “that sort of price” you can get low spec Android tablets. They aren’t overly impressive (if my “freebie” one is anything to go by), but there’s a screen large enough to look at, large enough to offer a full keyboard (plus the ability to use a Bluetooth keyboard), a processor more capable than you’d ever find in a calculator, and as an aside it can play movies, do the usual web browsing stuff, IRC, email, calendar, word processor, cloud, blah blah.

Here is a screenshot of my tablet doing some graphical Python stuff. I didn’t write it, it’s one of the demos. Not sure what I tweaked when prodding the screen but I quite like the result, it’s like an event horizon.

Full size : https://i.imgur.com/D1SlcbL.jpg

Worth noting is that the Python IDE was a big install that had to unpack a lot of stuff the first time, and then it needed to retrieve and unpack even more library code – matlab (IIRC?) and it’s dependencies took about half an hour to fetch and make wheels, whatever that means. I didn’t dare try any of the Qt5 examples.
Mind you, this pretty much makes David’s point about libraries. ;-)

So – why would somebody buy a smart-ish calculator when they could get a tablet that does so much more than a calculator for, uh, the same sort of price?

It’s got buttons.

Texas Instruments have/had a stranglehold on the “graphics calculators for schools” market in the US for many years. Not because their calculators were better than the competition, but because they managed to get their calculators featured in all the textbooks.

https://www.youtube.com/watch?v=zoGl8-Wc-L0

With the rise of tablets and smartphones I expect that TI, Casio, and others are starting to feel the crunch. Adopting Python may be one of their attempts to stay relevant – having Python on a calculator will be a lot more useful than the proprietary programming languages that you had to use before. And they can still try and convince schools that calculators are better than tablets precisely because of the fact that you can’t do half the stuff that Rick mentions. Sure, enterprising students will still install games on them, but for most students if a teacher sees that a student has a calculator infront of them then they can be confident that they’re doing work and not instagramming their latest myface tweet.

Beyond schools though, yeah, graphing calculators are pretty much pointless, and have been for several years.

graphing calculators are pretty much pointless, and have been for several years.

Decades?

I suppose you know Python has “made it” when it turns up in college-style calculators. Complete, I should add, with code colourisation, judging by the photos.

And some works with BBC Basic too :)

Decades?

That depends, since it’s probably “since school” for everyone.

One of the things about calculators which is easy to forget, is that they (by design) remain “offline” and “fixed function”. This allows them to be controlled in ways that phones/tablets etc cannot. For most purposes this is irrelevant, but in the schools market it prevents access to unauthorised materials during examinations. Calculators are usually permitted in science/maths exams, phones/tablets not so much ;)

Mind you, I remember graphical calculators had just appeared as I went through A-levels, and since basic calculators were permitted, so were they. I recall kids trying to cram formulae and notes into the (extremely limited) program memory as text strings to smuggle into exams. Not sure it helped them much, since they don’t help much in algebraic proofs, but it shows how any piece of technology will be abused given the chance.

Also, the manufacturers tended to partner up with schools to offer a “standard model” at a small discount. I recall being “taught” how to use a fairly basic model Casio calculator by a maths teacher who had (in the previous weeks) sent a letter round to parents offering this model through the school purchase scheme. It was probably five pounds cheaper than Argos or some such. The combination of “standard being taught by the school” and “discount” was enough to flock parents in droves.

Thinking about it, in hindsight, maybe Acorn should have made the schools into dealers… There’s nothing a school likes more than fundraising ;)

Texas Instruments have/had a stranglehold ..

There was a period in the mid-80s when TI were offering a special deal to universities comprising a desktop computer bundled with their Scheme interpreter and a copy of SICP (Structure and Interpretation of Computer Programs). As an educational package this made a lot of sense, as Scheme was always big in universities in the USA. They made a sales push for the UK, and Sussex University certainly considered it. In the end it was decided that Scheme, being typeless, was too old-fashioned. We started with ML for introduction to programming.