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## Mac cargo when only given a weight

• Posts: 105

### MissSoph created the topic: Mac cargo when only given a weight

Just going through a practice exam to find the max cargo able to be loaded.... however in the info I’m given that the pilot, empty aircraft and passengers weigh 2410kg...
I’m trying to do my beetle diagram...

• John.Heddles
• Offline
• ATPL/consulting aero engineer
• Posts: 523

### John.Heddles replied the topic: Mac cargo when only given a weight

Perhaps you might post the whole question as it was presented ? Sometimes we need to see the bit of string before we try to figure out how long it might be ....

Engineering specialist in aircraft performance and weight control.

• Posts: 105

### MissSoph replied the topic: Mac cargo when only given a weight

Question is asking max weight that may be carried in the rear compartment of an echo a/c...
Says weight of pilot, passengers, empty a/c and baggage is 2462kg
Fuel on board at take off..100 gal
Trip fuel to first landing point..35 gals

So I’m confused... am I just looking at how much weight to go before take off weight reached? Or do I have to do the beetle diagram to find out how much can be loaded in the rear... but then I don’t actually know how many pax are on the a/c... )

• Posts: 2184

### bobtait replied the topic: Mac cargo when only given a weight

It looks like you are reading too much into it.

You have been given the current ZFW of 2462kg. Assuming no limitations are imposed by runway lengths, the max take-off weight is:-
Take off max...................................2950
Landing max + fuel burn................2725 + 95kg = 2820
Max ZFW + all fuel.........................2630 + 272 = 2902
So you are landing weight limited at 2820kg.
You weigh 2462 without fuel, so add the 272kg of fuel you are carrying = 2734 kg.
Extra cargo allowed is 2820-2734 = 86kg.

No information is given on balance, so give that answer ignoring balance. It doesn't matter which compartment you use.

• Posts: 105

### MissSoph replied the topic: Mac cargo when only given a weight

Thanks bob xx I’m
Ready to crawl into the fetal position and stay there.... )
Trying really hard to get this performance stuff... self study is tough.... any pointers for perhaps reading and deciphering what the questions are asking of me? As you said... I’m reading too much into these questions and completely muddling myself up....
So maybe remember that if they are just asking for max cargo/ fuel ect.... no worrying about balance... then it’s as simple as just as we did above.... if it wants me to keep the plane in c of g... then all of the other stuff comes into play ?

• Posts: 2184

### bobtait replied the topic: Mac cargo when only given a weight

OK, you can come out from under the bed now!

Sometimes a question can be too easy. In that case you have been given the zero fuel weight, so there is no need to do a full 'beetle diagram'. Just add the fuel and you have the present load condition.

Keep at it. I'm sure you'll master it. Feel free to ask. Remember there is no such thing as a 'stupid question'.

Bob