Sexism in engineering language

[Nicholas FarrParticipant @nicholasfarr14254]

Hi, I agree with what MichaelG has said. If the aeroplane is flying upside down on a level path, the G force on it would be in balance, i.e. not going up or coming down, but gravity will still act on yourself, and hence, would be negative with respect to that of the aeroplane. If the aeroplane descends while upside down, faster than gravity would pull it, you would probably feel a moment of weightlessness, and then get the feeling of being pushed back into your seat, a bit like the feeling you get when going over a humpback bridge fairly fast in a car. At least that’s how I understand it, but someone will no doubt will correct me if I’ve got it wrong.

Regards Nick.

[Hollowpoint]

On Hollowpoint Said:

Again, I don’t see the need to alter language with a million new words.

Language evolves and is not set in stone. New words come into use, old words die away or their meaning changes over time. How words are put together also changes. I have several reprints of technical books from the beginning of the 20th century. They can be difficult to follow as the language is quite verbose and formal.

We have copper, brass, bronze, aluminium, steel, iron, nickel, chromium and the list goes on. For simplicity let’s just call them all metal.

Andrew

 

[JasonB]

On JasonB Said:

What is the point of a connector that mates to itself, or does it actually join to another identical connector?

It joins to another identical connector so only one component is needed, saves on inventory costs and pick ‘n’ place machine reels.

Andrew

[Hopper]

On Hopper Said:

My original question was maybe more in the league of idle musing, but whatever. I did not expect to open such a can of worms, but in retrospect probably should have!

Careful, you could be accused of trolling… Seems to me a perfectly reasonable tea-room subject. However, in these offence-taking days, an opened can of worms is only one word away.

[Kiwi BlokeParticipant @kiwibloke62605]

An example of nominative determinism. Thomas Crapper was a Victorian engineer who made WCs commercially. The c-word (not that one…) pre-dated him. He turned his unfortunate name to his advantage. I had the pleasure(?) of using one of his creations in UK, decades ago. The high-level cistern produced a Niagara-like torrent – and thunder – that would have had no difficulty of disposing of anything in the pan. Has this thread reached rock-bottom?

[JAParticipant @ja]

Standing on the Earth’s surface you are prevented from travelling towards the centre of the Earth by the reaction to you weight. This force equals your mass times gravitational acceleration. To increase altitude acceleration has to increase (usually slightly) etc. However there are things that change your altitude and add additional, non-vertical loads, to you such as aeroplanes, centrafuges, fairground machinary. If the acceration is high will you weight considerably more.

The body handles positive accelerations better than negatve (when you are hanging up side down). With 0 g you fall towards the Earth and negative makes the fall faster. If you are not strapped into an aeroplane subjected to -v g the plane is falling quicker than you and you hit the luggage lockers (and possibly make the news). If strapped in you can have other problems paticularly with the contents of your stomach (which would have been of little concern to a desperate ME109 pilot).

I am a little bit surprised I am posting this but I hope it makes sense.

JA

 

[Nicholas Farr]

On Nicholas Farr Said:

Hi, I agree with what MichaelG has said.

[…]

but someone will no doubt will correct me if I’ve got it wrong.

My correction herewith:

It was not I 

… I was reading an old book in a lovely Library at the time.

MichaelG.

 

[duncan webster 1Participant @duncanwebster1]

It wasn’t me that started calling it negative g, but thanks for the 2 float chambers explanation

Moving to Dave’s toilet, I thought it was snooty victorians copying the French ‘toilette’ on their trains. Does the word occur in English pre railway travel?

[Andrew Johnston]

On Andrew Johnston Said:

The actual problem solved by the small brass washer was that the Merlin carburettor flooded under temporary negative ‘g’.

Andrew

Anyone know why the Merlin used carbs at all given the superiority of fuel injection?

My guess is that, at the time, carbs were simple reliable technology, whereas injection on the BMW 801 engine required a fiendishly complicated electro-mechanical device called a Kommandogerät:

Getting fuel injection to do its stuff across the full range of conditions faced by a high-performance piston aero-engine is clearly much more complicated than squirting petrol in with a pump!  Unlike a motor car engine, an aero-engine has to cope with radically different air-pressures and temperature at different altitudes.  I think the way carburettors work mean that they cope without undue complexity, whereas injectors have to be told what to do, which requires calculation.

Although injection is better all round when set up correctly, I suspect that the relatively inferior performance of carburettors was accepted because they are much easier to get going and maintain than an WW2-era injector system.    And Miss Shilling’s problem apart, very reliable.

On the subject of sexism in engineering, I wonder if a stranger was ever crass enough to mention Miss Shilling’s orifice to her in person?  I expect so, many folk are tactless before booze reduces their inhibitions!

Dave

 

 

 

[SillyOldDuffer]

On SillyOldDuffer Said:

Anyone know why the Merlin used carbs at all given the superiority of fuel injection?

 

My guess is that, at the time, carbs were simple reliable technology, whereas injection on the BMW 801 engine required a fiendishly complicated electro-mechanical device called a Kommandogerät:

 

 

 

Because fuel injection didn’t really become superior to carbs until it was fully controllable by electronics. Just look at your picture and you’ll soon realise that it’s the sort of thing that only a German engineer cannot resist, especially when the Spitfire’s problem was solved by the clever application of a washer…..

[Chris CourtneyParticipant @chriscourtney72250]

The choice of carburettor rather than fuel injection wasn’t to do with complexity. According to Stanley Hooker (later to be Rolls Royce chief engineer)in his biography fuel injectors had a large performance penalty. For the Merlin the fuel was fed before the supercharger and the evaporation cooled the air by 25 degrees C, which enhanced the performance of the supercharger and increased the power of the engine, particularly at high altitude.

 

[Andrew Johnston]

On Andrew Johnston Said:

On JasonB Said:

Is flying upside down actually negative G. If you took your seatbelt off you would drop out of the plane so positive G is active.

I would say that flying upside down is negative ‘g’, at least from the viewpoint of the pilot. If I am flying the normal way up and undo the harness nothing happens; I stay in the seat. If I push forward positive ‘g’ reduces and if the ‘g’ reaches zero and then goes negative I will rise off the seat, restrained only by the harness. Similarly if I am flying upside down (-1g) I am lifted off the seat and am only restrained by the harness.

Andrew

And if you push the stick hard forward in normal flight, dust, grit and sweet wrappers fall from the floor to the canopy, just as if you had rolled inverted.

More info on aircraft fuel injection vs carburettors here:

And talking Spitfires and gender reassignment, consider Roberta Cowell:

https://en.wikipedia.org/wiki/Roberta_Cowell

[Andy Stopford]

On Andy Stopford Said:

And if you push the stick hard forward in normal flight, dust, grit and sweet wrappers fall from the floor to the canopy…

Been there, done that. After a simulated winch launch failure I pushed positively to get the nose of the glider down to maintain airspeed. All sorts of crap from the cockpit floor rushed upwards. The instructor complained I’d pushed too hard, I disagreed and quoted back the numbers and actions we’d just been lectured on.

Andrew

[Chris Courtney]

On Chris Courtney Said:

The choice of carburettor rather than fuel injection wasn’t to do with complexity. According to Stanley Hooker (later to be Rolls Royce chief engineer)in his biography fuel injectors had a large performance penalty. For the Merlin the fuel was fed before the supercharger and the evaporation cooled the air by 25 degrees C, which enhanced the performance of the supercharger and increased the power of the engine, particularly at high altitude.

 

But you could squirt the petrol in upstream of the blower with fuel injection. As others have said I reckon it’s the complexity that put our lot off. Someone once said a carburettor is a device guaranteed to deliver the wrong mixture at all conditions of load and speed, but at least it will continue to deliver something, whereas that complicated box of tricks could stop at the slightest provocation. There would have been plenty of German systems avalable for study after the Battle of Britain.

There is an astonishingly detailed description of Merlin carb development here

[Chris CourtneyParticipant @chriscourtney72250]

The complexity of the German fuel injection system was because it had to inject the correct amount of fuel into each cylinder at the correct time. Injecting a continuous stream of fuel upstream if the supercharger is a very different, and much easier problem. The difficulties with carburettors in the Merlin engine have become greatly overstated in more recent years. It caused some problems during the Battle of Britain, but obviously not decisive ones. It was essentially solved by the Shilling diaphragm and the later carburettor designs.

A very interesting link to the carburettor design article Duncan, thank you.
<p style=”text-align: center;”>I can recommend Stanley Hooker’s biography “Not much of an engineer” if you are interested in the development of piston and jet engines.</p>

[Michael Gilligan]

On Michael Gilligan Said:

On Nicholas Farr Said:

Hi, I agree with what MichaelG has said.

[…]

but someone will no doubt will correct me if I’ve got it wrong.

My correction herewith:

It was not I 

… I was reading an old book in a lovely Library at the time.

MichaelG.

 

Hi MichaelG, I do apologize, don’t know how/why I got you muddled up with JasonB’s comment about flying upside down.

Regards Nick.

[Michael GilliganParticipant @michaelgilligan61133]

No problem at all, Nick

Just felt obliged to mention it for the sake of clarity.

MichaelG.

[Andrew Johnston]

On Andrew Johnston Said:

On Andy Stopford Said:

And if you push the stick hard forward in normal flight, dust, grit and sweet wrappers fall from the floor to the canopy…

Been there, done that. After a simulated winch launch failure I pushed positively to get the nose of the glider down to maintain airspeed. All sorts of crap from the cockpit floor rushed upwards. The instructor complained I’d pushed too hard, I disagreed and quoted back the numbers and actions we’d just been lectured on.

Andrew

That is weightlessness where the pull of gravity is momenterily reduced eg goes negative because the loose items want to carry on as they were while the aircraft is put into a dive.

But when flying inverted you are still being pulled towards earth by positive gravity that is why Andrew says his belts hold him in, just like the bottom of the seat does when flying the right way up. I am talking continued inverted not just for a moment like you would get with a barrel roll or loop as there are other forces active in that situation.

The short period of being weightless when the spitfire goes into a dive won’t just affect the contents of your stomach or sweet wrappers, the float in the carb will also go light and lift and as it does so it shuts off the fuel.

That dust and those sweet wrappers don’t actually fall to the canopy, they stay in the same position in space while the canopy dives down making them seem to move upwards

 

[duncan webster 1Participant @duncanwebster1]

The article I referenced mentions the difficulty of getting the same mixture to all cylinders. On the merlin some cylinders had to run rich so that the weakest was still OK. It obviously worked, but if all running the same you use less fuel, get greater range.

[JasonB]

On JasonB Said:

 

The short period of being weightless when the spitfire goes into a dive won’t just affect the contents of your stomach or sweet wrappers, the float in the carb will also go light and lift and as it does so it shuts off the fuel.

Ah, but the ‘negative G’ causes the fuel to pour to the top of the float chamber, and the float still floats, only it’s now at the bottom of the chamber. The needle valve is thus fully open, and the over-rich mixture caused the Spit engine to cut.

[Kiwi Bloke]

On Kiwi Bloke Said:

On JasonB Said:

 

The short period of being weightless when the spitfire goes into a dive won’t just affect the contents of your stomach or sweet wrappers, the float in the carb will also go light and lift and as it does so it shuts off the fuel.

Ah, but the ‘negative G’ causes the fuel to pour to the top of the float chamber, and the float still floats, only it’s now at the bottom of the chamber. The needle valve is thus fully open, and the over-rich mixture caused the Spit engine to cut.

can you explain the bold bit. In a dive the float and I would think the fuel lift so the float will be surely beat the top of the chamber

[Kiwi BlokeParticipant @kiwibloke62605]

I had to think hard to come up with an analogy.

Think of a bucket of water, on the surface of which floats a ping-pong ball. Now whirl the bucket in a vertical plane, sufficiently quickly, so no water spills. What do you think happens to the ball? Try it…

[Kiwi BlokeParticipant @kiwibloke62605]

Perhaps you’re confusing ‘in a dive’ with ‘in a G-reversal situation’. In a steady dive, situation normal. It’s the transition that’s the problem.. Don’t forget that the plane can accelerate downwards at a greater rate than free-falling at 1G.

[JasonBModerator @jasonb]

But the plane is not going upside down during a dive like your bucket is. There are also other forces involved when swinging your bucket, the same as I said in a barrel roll or loop your bucket is going in a loop.

If your bucket were strapped into a plane seat then when it dives the water and the ball will come out of the bucket

 

Let’s throw another one at you. We have all seen film of astronauts in training floating about inside a diving plane. If flying inverted is negative G then why do they not fly inverted to simulate negative G rather than diving. Because if they did it in an inverted plane gravity would just pull them towards earth only being stopped when they hit the ceiling which is now at the bottom.

EDIT both typing at the same time.

I’m not confusing the two but others have said ” can someone explain why negative g caused by flying upside down is not a problem, but negative g caused by a sudden dive is? ” That is what I questioned as I feel flying upside down does not create negative G

[HopperParticipant @hopper]

The problem with going into a sudden dive was that the fuel rose to the top of the float bowl, and then poured down the float chamber vent lines into the carburettor intake and flooded the engine with raw fuel, causing it to stall. Fuel also flowed into the carb throat through various small low-speed passageways and so on that connected to the top of the float bowl.

At least, that is my understanding from the article Duncan linked to.

At the same time, it says, the float tried to “float” on the fuel that was now in the upper half of of the float chamber, so it actually pushed the float toward the (normal) bottom of the float bowl, thus opening the float needle valve, providing more fuel to keep the flow going down the vent tubes into the carb intake.

They had similar problems when flying upside down too. But the sudden dive problem was what allowed the German fighters to escape without the Spitfires and Hurricanes following them.

The US Packard-built Merlins were fitted with Bendix diaphragm “pressure” carbs that did not have this problem. They were impervious to attitude or G forces. So eventually RR fitted the same kind of carb and the rest is history.

The Shilling Restrictor was a stopgap measure that restricted the amount of fuel that could flow into the floatbowl so it could not supply more than the engine could burn. Crude, but simple and basically effective along with check valves in the vent lines and some other mods.

It’s all there in the linked article. Quite an interesting read. And the author refers to it as the Shilling Restrictor and says it was also officially known as the RAE Restrictor. No mention of nudge-nudge-wink-wink orifices, and quite rightly so.

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