Hi

The question stated and also any example I can find that is similer ie with the Alpha loading system and the need to plit the baggage load bwtween two compartments is the subject matter.
All examples indicate that if you split an 85kg baggage load into say 45 and 40 kg components ie for forward and rear baggage compartments that the moment is not considered at all for the rear baggage compartment. ie only the component related to the forward baggage compartment is utilised as the "line" passes straight down through the scale for the rear baggage compartment?

Hi Graeme,

In this question, you need to know what the max fuel load possible at take-off. The question also states you will need to load 85kg of luggage into the aeroplane but it doesn't state where you should put it. Since the nose and rear compartments each take a maximum of 45kg, you might as well put 45kg in the nose and the remaining 40kg in the rear compartment. You could put 45kg in the rear and 40kg in the nose if you wanted. It makes no difference to the answer in this particular question because there is only a small difference in the final position of the CofG with the two loading options.

You do not ignore the moments of the nose and rear compartments as you mentioned. You pass vertically down through the fuel section (not the rear compartment section) since fuel does not change the CofG position forward or backwards. Adding weight to the forward or rear compartments does change the CofG position. Adding baggage to the nose moves the CofG forward and adding weight to the rear moves the CofG backwards. The interesting thing about fuel loading in the Alpha system though is the fuel tanks are right on the datum so adding fuel doesn't make the CofG position move forwards or backwards from it's current position (fuel generates no moment).

Getting back to the question, once you have loaded the gear and the passengers it is time to start loading the fuel. Plot the CofG position with no fuel loaded. This is the CofG position at Zero Fuel Weight (ZFW). From that point we simulate adding fuel by following the line straight upwards to the limit of the envelope. The difference between this maximum permissable weight and the ZFW is the amount of fuel we can legally add for this flight.

Take another look at the examples starting on page 1.3.4 in the PPL textbook for a detailed working of the Alpha loading system.

Cheers,

Rich