Trim Tank

[littlejet]

I need some info (link) about fuel system designs regarding the aircraft C.G. movement and preservation within limits. The principle of fuel trim tank?
Thank you, and Seasons Greetings
L.

[blackmail]

hi littlejet,
the concord(rip) used to transfer fuel from forward fuel tanks to aft fuel tanks, when accelerating towards supersonic (M2.0) cruise speed.
due to schockwaves over the wing when going supersonic, the center of pressure (cp), which is the origin of the resultant liftvector, moves aft & so to remain balanced in pitch, the aircraft center of gravity (cg), must also move backwards. this was achieved by transferring fuel to the aft fuel tanks.
it was a fulltime job for the flight engineer(gasp!) to keep the ship in balance during this acceleration & subsequent supersonic cruise flight. there was a gage on his panel with two adjacent vertical scales, one representing the cp location by a small gap between 2 automatic sliding bugs & the other scale representing the aircraft cg by a single sliding bug. the trick was to keep the cg bug in between the gap of the 2 cp bugs, by a continuous & measured transfer of fuel rearwards. concord's fuel management was something of a black art, having as many as 17 or something, number of fuel tanks.
the actual subsonique barges we now have, when so equipped, transfer fuel from tail to wingtanks, just to keep cg more or less constant.
concord trimfuel was not burned because this fuel was needed in the forward fuel tanks again, when decelerating.
aerodynamic center(point where all lift changes occur) for concord was at circa 50% MAC(mean aerodynamic chord), whereas subsonic aeroplanes have their ac at circa 25%MAC.
kind regards &
merry x mas
bm