Fuel Savings From Cg
Thread Starter
Join Date: Nov 2004
Location: Dublin, Ireland
Posts: 105
Likes: 0
Received 0 Likes
on
0 Posts
Fuel Savings From Cg
Hi all,
Can somebody quantify the fuel savings of an aft Cg as opposed to an extrem Fwd Cg? i would really be interested to know what the difference is in real numbers.
we have always been taught that an aft Cg saves fuel and some w&b systems actually suggest an optimal LIZFW (usually around 10pt from aft limit)
Is it worth my while trying to achieve an optimal Cg on a short sector eg dub-fra ??
thanks, john.
Can somebody quantify the fuel savings of an aft Cg as opposed to an extrem Fwd Cg? i would really be interested to know what the difference is in real numbers.
we have always been taught that an aft Cg saves fuel and some w&b systems actually suggest an optimal LIZFW (usually around 10pt from aft limit)
Is it worth my while trying to achieve an optimal Cg on a short sector eg dub-fra ??
thanks, john.
Join Date: Sep 1998
Location: wherever
Age: 55
Posts: 1,616
Likes: 0
Received 0 Likes
on
0 Posts
We had correction factors in the old L1011 AFM but I don't recall them off the top of my head. But for sure it was real and on long sectors when loaded aft of that used in the jet plan the savings were considerable.
Join Date: Dec 2003
Location: USA
Posts: 194
Likes: 0
Received 0 Likes
on
0 Posts
Join Date: Sep 1998
Location: wherever
Age: 55
Posts: 1,616
Likes: 0
Received 0 Likes
on
0 Posts
conversely some manufacturers offer Forward CoG schedules to improve take off perf. Ideally you would like to have it forwards for take off and then shift it back in flight which is what many jets do now.
Join Date: May 1999
Location: UK
Posts: 157
Likes: 0
Received 0 Likes
on
0 Posts
Join Date: Sep 1998
Location: wherever
Age: 55
Posts: 1,616
Likes: 0
Received 0 Likes
on
0 Posts
ssg might be better off reading this one: http://www.flightlevel400.com/docume...erformance.pdf
Join Date: Sep 1998
Location: wherever
Age: 55
Posts: 1,616
Likes: 0
Received 0 Likes
on
0 Posts
FE Hoppy
Nice link to Airbus V1 philosophy. Mike McCook doesn't ring a bell, where might I have met him? I'm an exile from some of ssg's threads.
Nice link to Airbus V1 philosophy. Mike McCook doesn't ring a bell, where might I have met him? I'm an exile from some of ssg's threads.
Moderator
I recall a presentation from a QF fellow at the RAeS some years ago .. relating to a study (which was driven by a pilot's interest, rather than the engineering folk at it turned out) which looked at rescheduling the tailtank usage on the 744 to constrain the aft cg a little more ... long range it was worth a couple of (fare-paying) extra passengers .. over a year, something in excess of a lot of money.
Join Date: May 2008
Location: MarysVille
Age: 63
Posts: 54
Likes: 0
Received 0 Likes
on
0 Posts
I checked out the Nasa link for aft CG...can't say it applies to all planes, but they seem to make it clear that if you can leave the fuel as far aft for the duration of the flight....2% savings is the approximate result.
Begs to ask the question of why we still hang our tails on the end of the plane the way we do...
Begs to ask the question of why we still hang our tails on the end of the plane the way we do...
Join Date: May 2008
Location: MarysVille
Age: 63
Posts: 54
Likes: 0
Received 0 Likes
on
0 Posts
Couldn't agree more Hoppy...I guess in some cases trying to save a buck on fuel, or engines, or whatever, we could end up reducing safety...defeats the purpose if the plane goes in.....