mass and balance question, can anyone answer this one

[gphillips134]

how much mass must be added to a hold at -150 inches, in order to move the c og g of a 52900kg aircraft 120 inches forward from its initial position of +515 inches

an explaination would be most helpful with this

thank you

[Dufwer]

Corr! What a cr@p question. Most I have seen are "how much must be moved from hold A to hold B" so I had to think about this one.

If y = amount to be added

then 395 * ( 52900 + y) = ( 52900 * 515) + ( y * -150)

Logic being the new moment (new postion 395 times new weight [52900 + y]) equals the old moment ( 52900 * 515) plus the moment of the new weight (y * -150).

20895500 + 395y = 27243500 - 150y

395y + 150y = 27243500 - 20895500

545y = 6348000

Answer y = 11648kg



I'll await other responses :suspect:

D

[OneIn60rule]

Come up with 31421.8 KG

m/M=d/D

515-120= 395 = d
515+150= 665= D



m = not known
M = 52900

so now> m/ 52900 = 395/665
m/52900 = .5939849 = m = .5939* 52900= 31421.8


I usually draw a line for such questions and insert the valid info into it as so>


-150 0 120 515
------------------------------------------------------------------------------

you know the weight and you know how far and what is the maximum it can move between -150 and 515.

Not sure if it's correct since I'm a bit tired right now.

[GearDoor]

I came up with 11648 kg also.

-150 x +(515) (52900) = (515-120) (52900 +x)

[pa28biggles]

Required Mass/Old Total Mass = Change of CofG/Distance of new CofG from hold

Required Mass/52900 = 120/((515-120)+150)

Required Mass/52900 = 120/545

Required Mass/52900 = 0.2201835

Required Mass = 0.2201835 x 52900
= 11648Kg

[gphillips134]

well done to those who aswered correctly - 11648kg
many people looked at the question but only four attempted it,
tune in next week for some more wacky questions

[coolguy]

Ask Patrick Geary at LGU he does a very good job for Mass and Balance , I passed because his hard work,,,,,

[Jinkster]

Did anyone sit it this time in January?

Was there anything "out of the blue"?

what did the big markers at the end ask?


I am sitting in Feb.

Jinkster