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Volume
8th Oct 2004, 07:47
Had another domestic flight in a Canadair CRJ200 early this week. It was just the typical scene, business class in the front of the airplae was completely full, while some econmy passengers were scattered in the aft the airplane. (I will never understand, why operaters do so, if the seat pitch is identical in both classes and the business class is full, while economy is almost empty, why is the comfortable class the cheap one :confused: )
Most interesting to see was, that dozens of heavy sandbags were unloaded from the aft cargo compartment, which otherwise contained just a small number of small bags. Looking a little closer, I found out that most baggage handling trucks had some sandbags stored in a seperate compartment, so obviously they are needed often.

Do you need to carry some ballast in the rear cargo hold to maintain forward CG limits if the front cabin is fully seated and the rear cabin is empty ? Do we really spend a huge amount of money and accept a maintenance and crack repair nightmare just to save some weight during structural design, and add ballast weight during operation ? Do operators really spend money (additional fuel burn) just to seat business passengers less comfortable in a crowd in the front cabin ? Are there other types of aircraft around where you need to carry ballast to maintain CG envelope ?

Flap Sup
8th Oct 2004, 09:59
Volume,

under normal circumstances operators do not leave empty seats in business while eco is empty. You must have been a victim of poor planning.
In those aircraft the config can be changed in a second, and it usually is, if the airline sees that the business booking has gone up. It could have been that a lot of eco passengers were no-shows or misconnected for the flight, but then again, you may just have been unlucky.

Several aircraft types require ballast for partially empty, partially full or ferry flights. Emb135-145, MD80, F100, Caravelle among some. You may see a connection, as all of these aircraft have tailmounted engines. One Emb145 may require ballast for a full flight where another may not even though they have exactly the same payload, the difference may come down to the actual aircraft. One ac may have a heavier pantry, another may have thrustreversers. All those xtra weights influence the need for ballast.

But trust me, no operator likes to load ballast on any plane!

/fs

rotornut
8th Oct 2004, 11:35
Are there other types of aircraft around where you need to carry ballast to maintain CG envelope ?
I seem to recall that in the Bell Jetranger the minimum front seat total weight is 150 lbs.. Therefore for lighter pilots going solo you may have to add a few pounds of ballast.

CR2
8th Oct 2004, 11:44
Similarly an empty converted pax to -F B747 usually requires some sort of ballast on a ferry flight.

Elliot Moose
11th Oct 2004, 02:39
The 200 is generally a very nose-heavy aircraft to begin with. Just look at them--everything in front of the wing and not much behind, except baggage. Therefore, if "up front" is full, and not much in the aft, it easily gets out.
They actually have a fairly generous C.G. range, but you do have to keep the folks a bit more aft as a rule. Problems do arise on short business shuttle operations where everybody shows up with a briefcase and an overcoat and nothing else, since there ends up being nothing to hold down the rear. The 700 series has a fair bit more behind the wing, and as a result the problem isn't really there to start, and it has both forward and aft cargo to help move the CG around as needed.