Hi Mark,

No you are not going mad, it looks like there's a misprint in the workings for that question. I'll take a closer look at it and correct it on Monday. I see you got the right answer though so good on you!

By the way, since you are adding weight with a fixed fuel load, you would have to re-check your ZFW CofG position with the new loading to be thorough. It is possible with some aircraft to add all that weight to bring you up to MTOW only to find you have put yourself out again at ZFW.

Cheers,

Rich

Mark, I have updated that answer now. Please take a look and see if that clears everything up for you.

Cheers,

Rich

Hi Richard

Thanks for the update, yeah i didnt realise that your COG could be out at ZFW but still be in at max Takroff so I am just going over your method because it differs abit from mine, but glad we got the same answer

Cheers for the update Richard, appreciate all your hard efforts

Kind Regards
Mark Chetcuti

just spotted another mistake, the new all up weight including fuel should equal 2200 LBS but you have equaled it to 2026 without adding fuel, just being a bit picky now Rich haha

Cheers

Hi Mark,

That will teach me to update questions when tired eh. Sorry about that, I'll fix that typo.

The problem with being out at zero fuel weight and in at all-up is not so much of a problem with Alpha, Bravo and Charlie but it is a different story when you meet the Echo at CPL level. You will see she has no end of loading gotchas.

Apart from that, it is actually a legal obligation to check the weight and balance at ZFW and all-up weight.

Cheers,

Rich

Hi Rich

I have been looking at the echo aircraft lately on my cpl performance that i ordered, seems pretty straight forward atm but def a lot more to consider!! Mate appreciate you getting back to me so quick, just thought I would stir you up a bit 🙂

Cheers mate

Hi Mark,

Just checked it out and found it isn't a typo. The 2026 is the new ZFW we get after adding the 301lbs to Row 2. The new all up weight is still 2200lbs but we are talking about ZFW in that part of the solution 🙂

Cheers,

Rich

Hi Rich

Even we're it says new ZFW 2026 plus fuel = 174 then says all up weight still equals 2026, Is that still right, just thought I would ask mate

Cheers Rich

Right you are Mark - all fixed now (I hope 😉 ). Silly copy paste error that one - thanks for pointing it out.

Cheers,

Rich

Haha mate no problems, glad I'm on the ball, always a good sign picking up the professional's mistakes

Cheers

Hi rich

Just wondeing if the shift to weight formula also works with the charlie loading system or does it just work with the bravo loading system

chers

Hi Mark,

The formula works for all aircraft types. It is based on the physical principle of calculating moments:

[b]Moment = Weight x Arm[/b]

and is a manipulation of a derived formula:

[b]w/W = D/d [/b]

where:
[b]w[/b] = the weight to shift
[b]W[/b] = the weight of the aircraft
[b]D[/b] = the distance the aircraft's centre of gravity is to be moved
[b]d[/b] = the distance the load is moved i.e. the difference in arms.

If we rearrange that second equation to solve for [b]w[/b] we get the familiar formula for shifting weight:

[b]w = (W x D)/d[/b]

The same formula applies when adding or subtracting weight too. The only difference is the value [b]d[/b] to be used: it would now be the distance between the arm of the compartment where you are adding/removing the load and the desired position of the CofG.

I stumbled across a [url= http://www.avcanada.ca/forums2/viewtopic.php?f=3&t=65644 ]derivation of the weight to shift formula[/url] at the AVCANADA.ca website which saved me a heap of typing. Here it is for your edification 🙂

[attachment=399]WeightShiftEquation.pdf[/attachment]

That is just for fun and not needed for the exam.

Cheers,

Rich

Hi Rich

Thanks so much for your help mate

Kind Regards

One problem with the Alpha and Bravo loading systems is that you don't know exactly where the aft limit is as a distance from the datum. They don't give you that information so you have to plot it on the envelope. So you cannot use a formula or flow chart [which is exactly the same calculation as the formula], because you don't know how far the centre of gravity has to be moved. The Charlie loading system does give you the aft limit as 3004mm from the datum, so you can use a formula or flow chart to solve its aft limit problems.

In all loading systems I know of, the forward limit varies with gross weight, so you can't use a formula to solve weight to add or subtract problems on the forward limit.

Bob