Could someone please explain the difference between...proportional and all that ****

[Jinkster]

I maybe a bit fik but could someone explain in basic terms the meanings of proportional, directly, inversley proportional to.....

Many thanks in advance,

Jinkster

[FlyingForFun]

These terms are used to relate two numbers to each other.

"Proportional" means that as one number increases, the other number increases as well. The weight of your aircraft is proportional to how many pork pies your passengers had for lunch.

"Directly proportional" means that as one number doubles, the other number doubles. The distance you travel is directly proportional to how long you fly for (assuming your speed is constant).

"Inversly proportional" means that as one number increases, the other reduces.

If you have specific examples, post them here and I'll try to explain how the terms to be interpreted in your examples. There is a bit of flexibility - for example, "proportional" can often be used to mean "directly proportional", depending on the context.

FFF
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[Penworth]

Directly proportional means that if the terms on one side of an equation go up by a particular factor, then so do the terms on the other side increase by that factor. For example, if X and Y are directly proportional, then doubling X will see Y double as well.

Inversely proportional is the opposite, if X is doubled (ie multiplied by 2), then Y will be halved, effectively multiplied by 1 over 2. Whatever factor you multiply one term by, if another is inversely proportional to it, you divide it by the same factor (in this case 2).

Hope this helps!

PW

[OneMileHigh]

Sorry Jinkster but: What I am about to say may seem a bit harsh, but sometimes a reality check is called for.

You are aiming to be an Airline Transport Pilot, where intelligence is an absolute requirement for the job. The ATPL theory exams partly fulfil the role of removing the unqualified from the potential pilot pool, but also gives those without the required knowledge and intelligence the chance to develop. For many it takes a lot of time and money but they get through, and in a lot of cases this forum provides many answers to many questions.

Now I am not saying that every pilot should know beforehand the meaning of proportionality and whether it is applied inversely or not, but it would normally be assumed that an aspiring commercial pilot would have this knowledge. However my worry with you is that you are immediately resorting to an internet forum like Pprune without any attempt at self help. What has happened to books in your life, or even the wider aspects of self study using the net.

What impression are you giving to potential employers where nearly all the planning and preparation you would do is by self analysis and using written information effectively. Even met briefings are done without the old fashioned met man to help.

Now please don't take all this critisism to heart, because beneath it all is good sound advice. Self study is an essential part of life for anyone aiming for a higher employment level, and it is a habit you would do well to adopt.

[witchdoctor]

And don't forget arrogance.

Arrogance and a superiority complex...........both absolutely vital!:}

Jargon and big words are for clever people who like to make themselves feel even cleverer by describing simple concepts in impressive ways to confound less clever people.

I suspect you don't bake too many cakes, so let's use beer as an example;

Directly proportional would describe the fact that when you drink more beer you become more pissed - (one up, the other up).

If you are a big lad, then you will be able to consume more beer than your little buddy, who will get pissed faster. So if you both drink 10 pints before climbing into your aircraft, he will have drunk proportionally more than you as he is so much smaller, and 10 pints occupies a much greater amount of his body.

Indirectly proportional would describe your ability to commit rumpy pumpy with the trolley dollies - more beer, less performance (one up, one down).

Easy really, and no stupid 'I'm a smart arse maths teacher' twaddle from a text book.:D

[RowleyUK]

Wannabes A forum for those on the steep path to that coveted professional licence. Whether studying for the written exams, training for the flight tests or building experience here's where you can hang out

So therefore if you know what proportional,direct or inverse mean then this is the place to be!!

Take Off Distance is proportional to Weight. ie, weight increases therefore take off distance will also increase!


Temp is inversely proportional to Altitude.ie Altitude increases but the temperature decreases!

Hope this helps!


:ok:

[Old King Coal]

W.r.t. 'Temp is inversely proportional to Altitude. ie Altitude increases but the temperature decreases!'

For the avoidance of doubt, that's not strictly true but is mostly correct at lower levels ( and / or temp inversions aside ).

[Jinkster]

Thanks for all the replies.

I am not really thick by no means. However how the :mad: am I expected to know what all these words mean if no one has actually told me in the first place!!!

After studying GCSE and A-Levels I had never come across those words before studying for my ATPL.

Many thanks for all the helpful replies and for the others I am sure that yourselves will come across things you dont know in the future. God forbid the people helping you wont have the attitude you have taken!!!

[High Wing Drifter]

After studying GCSE and A-Levels I had never come across those words before studying for my ATPL.
Its a funny upside down old world. I don't have any maths qualifications (In fact I don't have any qualficiations worth speaking of - now how scary is that?) and yet I was quite familiar with these terms and indeed with all the maths in the ATPL syllabus. I suspect you probably did but filed that information in the circular filing bin in your head marked "useless for everyday things." :8