"PTOBO", question from a friend
Thread Starter
Joined: Jan 2005
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From: France
"PTOBO", question from a friend
Does anybody know what "PTOBO" would refer to?
This is in the Concorde Vol IIa flight manual.
Could stand for something like "Pre-Take-Off Balance-Offset", but solving this riddle would please both me, and the friend who asked me the question 
CJ
This is in the Concorde Vol IIa flight manual.
The aircraft must not be taxied with a PTOBO in excess of :-
3300 kgs for a 53.5% take-off
1800 kgs for a 54% take-off
3300 kgs for a 53.5% take-off
1800 kgs for a 54% take-off
CJ
Joined: Sep 2007
Posts: 128
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From: UK
Pre Take Off Burn Off
The fuel required to be burnt during taxy to allow txfr from tank 11 to tanks 5 & 7 to achieve TO CG (53.5% or 54%).
Used when ramp CG aft of TO CG (ie high fuel load)
Alternative was Pre Take off Transfer when ramp CG ahead of TO CG - fuel txfrd to tank 11. Much quicker and less hassle.
The fuel required to be burnt during taxy to allow txfr from tank 11 to tanks 5 & 7 to achieve TO CG (53.5% or 54%).
Used when ramp CG aft of TO CG (ie high fuel load)
Alternative was Pre Take off Transfer when ramp CG ahead of TO CG - fuel txfrd to tank 11. Much quicker and less hassle.
Thread Starter
Joined: Jan 2005
Posts: 2,315
Likes: 10
From: France
EXWOK,
Never had to do Concorde "fuel-and-CG math" myself, so I take your word for it.
(I helped to build 'em, not to fly 'em.)
I would assume that when you got up to the limits, a close watch was kept on what went into the rear baggage hold, as well.
Also, to start worrying about PTOBO, you'd probably already would have "over-filled", no?
(For those unfamiliar with the aircraft, it's a Concorde trick, where you "top off" each tank with a carefully metered dose of fuel after the "high level" indication comes on. Don't know if it's done on other aircraft.)
CJ
Never had to do Concorde "fuel-and-CG math" myself, so I take your word for it.
(I helped to build 'em, not to fly 'em.)
I would assume that when you got up to the limits, a close watch was kept on what went into the rear baggage hold, as well.
Also, to start worrying about PTOBO, you'd probably already would have "over-filled", no?
(For those unfamiliar with the aircraft, it's a Concorde trick, where you "top off" each tank with a carefully metered dose of fuel after the "high level" indication comes on. Don't know if it's done on other aircraft.)
CJ
Last edited by ChristiaanJ; 17th September 2009 at 16:51. Reason: clarified my scribble
Joined: Sep 2007
Posts: 128
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From: UK
No need to overfill....you'll recall that tank 11 sits higher than all the others. So CG remains roughly constant until tanks 1-10 are full, then it starts to run aft as tank 11 continues to fill. So PTOBO vs PTOTR is a function of ZFCG and total fuel load.
We would sometimes encourage the loading of the aft hold in order to achieve a 54% take-off if heavy for its (small) fuel burn and performance benefits. Careful ZFCG management would minimise the Burn/txfr..
There was always more to the operation of this aircraft than first appearance suggested!
We would sometimes encourage the loading of the aft hold in order to achieve a 54% take-off if heavy for its (small) fuel burn and performance benefits. Careful ZFCG management would minimise the Burn/txfr..
There was always more to the operation of this aircraft than first appearance suggested!
