Mass & Balance questions

[FliegerTiger]

Can anyone help me here? Am I missing something? I have no clue how the answers of these questions were arrived at (source - OAT exam prep CD-ROM)

1) Using the data for the aircraft below, assuming that the traffic load to be carried is as shown, what will be the block fuel for take off at MTOM?

Crew & equipment - 280kg
MTOM - 12154kg
MZFM - 3227kg
BEM - 1457kg
Start/taxi fuel - 250kg
Trip fuel - 8450kg
Flight duration - 3 hours
Pax - 720kg
Baggage - 4435kg

a) 7677kg
b) 8972kg
c) 9512kg
d) 9262kg

answer given = c)


2) A cuboid box of dimensions 0.8m x 0.8m is to be placed into an aircraft hold with a maximum distribution load intensity of 5000N/sqm.
What is the max. mass that can be loaded in the box? (assume that acceleration due to gravity is 10m/sec sq.

a) 800kg
b) 40kg
c) 400kg
d) 80kg

answer given = d

For this one I would have thought it was a simple question of ratios, ie.

MDLI= 500kg/sqm

therefore 500/1 = x/(0.8 x 0.8)

therefore x = 320kg, not given here....

where am i going wrong?

Cheers, FT

[The Greaser]

Tiger :

I think you are looking at 2 misprints here -

Question 1 : Baggage = 435kg : gives correct answer

Question 2 : Box must have dimensions of 0.4x0.4x0.4

Your reasoning for #2 is correct, if you need an explanation for #1 then let me know

[FliegerTiger]

Thanks, Greaser...

That was my keying error on #1, still don't quite get it. Could you work through it please?

Cheers,

FT

[The Greaser]

No probs tiger :

Takeoff is to be at MTOM = 12154 kg
Start/Taxi fuel = 250kg

so ramp mass = 12404 kg

-----------------------------------------------------------------------


BEM = 1457 kg
Crew/equipment = 280kg

so dry operating mass = 1737kg (may also be called APS)

traffic load = 1155 kg (pax + baggage)

so zero fuel mass = 2892kg

------------------------------------------------------------------------

Block (ramp fuel) = ramp mass - zero fuel mass
= 12404 - 2892
= 9512 kg

[Alex Whittingham]

"therefore 500/1 = x/(0.8 x 0.8) "

therefore x = (500*0.16)/1
and x = 80kg

[The Greaser]

0.4 x 0.4 = 0.16

0.8 x 0.8 = 0.64

[Alex Whittingham]

Doh! - didn't have my maths head on. I agree about the typo, the area should come out at 0.16 square metres.

[FliegerTiger]

Thanks guys. Alex, see you end of October for Mod 1 brush-up!

FT

[The Greaser]

Well I probably wouldnt be able to answer these without Alex and his team, as I went through Bristol 3 years ago. Good luck FT.