Weight (mass) and fuel burn relationship

[miles offtarget]

Hello,

Anyone have a handy reference for why fuel burn increases with an increase in aircraft weight ?

I understand that theory, but need a source document to quote in an academic paper which has a little more authority than my tatty and trusty old PPSC ATPL notes !

Cheers, and thanks as ever.

MoT

[BOAC]

but need a source document to quote in an academic paper - you are not serious, I hope? Exactly what level of 'academia' are you addressing?

[miles offtarget]

Why are you being rude BOAC ?

I'm in a public library without access to any technical manuals, and am seeking a quick internet reference to something like AP3456 (or whatever the RAF equivalent is now) or something generic from the CAA/FAA.

The academia is a post graduate dissertation validating computerised flight and fuel planning assumptions when operating B737 aircraft within the London TMA, but I don't see that makes much difference to my request.

If anyone else could help me I'd very much appreciate it.

Thanks.

MoT

[BOAC]

I'm not being rude, just incredulous. If I had to prove to 'academia' that dragging two kids on a sledge needs more effort than dragging one......................

[mutt]

Google..... getting to grips with aircraft performance...... Look in the cruise chapter.

Mutt

[BOAC]

Thanks for a word (Epistemology) I did not know (and never heard at university). "Verifiable first principles, a null hypothesis and robust methodology". Will you need to prove to them the relationship between mass and weight as well and the concept of gravity itself? A big paper, I feel. Quite glad I turned down the offer of a post grad place.

You, are, by the way, welcome to the 737 fuel burn figures at different weights if that might help. I'll watch your parallel universe thread with interest.

[miles offtarget]

Mutt,

Thanks mate, very much appreciated.

MoT

[BOAC]

Beware Smart Cockpit - the more alert of your academics may ask you to show why Thrust (aka fuel burn) is proportional to wing area (which it isn't) (p28 4.1.1.2).

[john_tullamarine]

miles offtarget,

(a) let's not delete the thread - the question is quite valid and should remain.

(b) you need to expect the (more experienced) airline pilot fraternity to be critical - nature of the business. No different to academic peer review in principle .. but tends to be a tad more in your face, as it were - again nature of the business - flying can't afford to be too PC due to the occasional risk of dying during the PC bit. The older folk tend to understand that from near bitter experience.

Come to think of it, I have seen the occasional academic review which was far more acid than this thread's commentary ...

[latetonite]

Trust you can make the equation yourself. Start with F=M*A....

[miles offtarget]

Hello John,

Thanks for your input, you are absolutely right of course.

I only intended to delete the post because BOAC turned a quick enquiry for a reference into a bit of a pointless 'you are not serious, I hope' ad hominem, and so sent the enquiry off topic. I was just going to rephrase the question and post again.

I explained that I knew the answer in my initial post, (I have been flying either for the RAF or commercially for 25 years), but as you are aware, to some extent an author's conjecture or unqualified statements are inadmissible as evidence in an academic context. I needed to reference an existing high quality source in order to demonstrate the weight/fuel burn concept to someone with a background in physics, but not necessarily a background in aeronautics.

After all that's what differentiates academic literature from journalism.

As Latetonite illustrates, it can be a simple but a poorly understood concept, even when most of us can make the equation ourselves (from F=MxA or elsewhere). I suspect however it's not important, not all pilots have good degrees, and in my experience having a good degree certainly does not make one a better pilot !

Ultimately though I suspect the fault is mine, there is a fantastic amount of good technical stuff on PPRUNE, and as you say some very experienced posters who are happy to help, but in contrast to say Dr Net for the medical profession, it is above everything else a rumour rather than research network.

Must dash, have a paper to write.

All the best, and thanks as ever.

MoT

[jonnyn]

And there's no arguing the pedigree:

Newton, Isaac: Principia, 1684

[john_tullamarine]

it is above everything else a rumour rather than research network.

That's not to say it's better or worse, only different. A large emphasis is placed on quiet education without the rigour of academia.

Pilots, as a body and because of the nature of the task, are high ego folk and tend to react better to gentle persuasion ... with some OWTs in this Industry being so deeply entrenched that they are unlikely to be eradicated.

Fortunately, and in general, aeroplanes will fly quite nicely with a goodly dose of SOP even with an absence of defensible rigour in the dissertation ... we just continue to chip away, I guess.

[rapidshot]

i understand the question as an increase in weight of a specific aircraft,

if it is so , (sorry but not quite academic),

as the weight of the aircraft increases you have to fly with higher lift coefficients which increases the induced drag

[nomorecatering]

How about having a look at the book Aerodynamics for Naval Aviators published by the US Navy. A standard ATPL text here in Oz.

[barit1]

Look up induced drag and the connection becomes evident.

[miles offtarget]

Thank very much, will have access to tech library shortly and so will be able to reference it.

Cheers.

[BlankChecks]

Notice how no one answered the question and ran off the OP with the moderators help?