Cant give you an answer to your first question as I have never flown military aircraft. But having been around them yes it is normal procedure to drop the tanks when entering combat. In the more information than you wanted to know category...
The normal fuel transfer procedure from external to internal is to transfer fuel from the centerline tank first, then from the external wing tanks. However, this may be overridden by setting the fuel transfer switch to wing first according to the Falcon manual.
The fuel system of the F-16 is based on the
Forward/ Right Left /Aft layout.
The fuel is divided into two systems, the F/R and L/A, and is fed from both systems to the engine. In this way balance is maintained and the aircraft does not become too nose or tail heavy or have a tendency to roll.
The fuel storage system is composed of the following:
•Two Reservoir tanks, these hold 480lbs of fuel each and feed the engine directly. One reservoir is for the F/R and the other L/A system.
•Forward and aft fuel tanks hold the bulk of the internal fuel. They feed into the appropriate reservoir tanks.
•The wing tanks which feed the forward and aft tanks, the left wing tank feeding the aft main tank, and the right feeding the forward tank. These tanks hold 550lbs of fuel each.
•External tanks feed into the wing main tanks. The wing externals feed into the appropriate wing tank, and the centerline feed into both. Capacity is dependent on the tank size loaded.
The fuel is transferred from the reservoirs to the engine. There are fuel pumps that are normally activated to aid the transfer, but the main transfer mechanism is gravity and siphoning between tanks. The fuel then goes through the Fuel Flow Proportioner (FFP). It adjusts flow rates from the two systems to maintain the balance of fuel between F/R and L/A systems to maintain the aircraft’s center of gravity. Should the FFP fail (it is part of the ‘A’ hydraulic system) then erratic distribution may occur leading to a center of gravity imbalance.
The fuel then goes through the main fuel valve to the engine (where it burns!). The amount of fuel in the F/R and L/A is shown on the fuel gauge. More important is the ratio of the fuel in the tanks. If the difference is too large, a center of gravity imbalance will occur. Attention to the fuel gauge indicators is important beyond just assessing remaining fuel.
Many thanks for the info. I remember, when reading about the IAF raid on the Osirak reactor, it was made possible because the Israelis had just received their first F-16s a few months before, and the were modified to carry an external centerline tank. The IAF was concerned that when the tanks were jettisoned, they might strike the bombs under each wing...seems there was minimal clearance..and either damage them, or possibly cause a detonation..Happily, all went perfectly.
“But having been around them yes it is normal procedure to drop the tanks when entering combat.”
No, it is not. You drop them only if you need to do so. Otherwise you bring them back and reuse them.