Forum: F-16 Procedures

Newbie Joined: Feb 03, 2004 - 07:58 AM Posts: 2

I would like to know which fuel is burned first when a viper is carrying external fuel tanks. Is the fuel in the external tanks burned first or is it the fuel in the internal tank?

Does the fuel from the external tanks has to be transferred into the internal tank before it can be used.

Tiger Greetings

F-16.net Sponsor

Oh I'm sure the troops will chime in on this soon enough....so I'll let them explain it... Very Happy

Fuel from the external tanks is transferred into the internals as the engine roars. Fuel is actually fed through the main fuel line to the engine and replenished during this constant process until the externals are empty. As gee wiz information, the externals will not transfer if the air refuel door is open.
Lee

Confirming LeeRichardson's answer (and geewhiz) Smile

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 4 (SP3) manual.

According to that same 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.

Newbie Joined: Feb 03, 2004 - 07:58 AM Posts: 2

Thanks for the info guys

Tiger Greetings

Absolutely awesome explanation Whity!

Hell we taught this stuff back in '79 and it doesn't look like it has changed. Guess a good idea is a good idea.

BTW, the first crash was a troop that left the air refuel door open. Was in a B-model, so he also had the flaps down, causing even more fuel flow problems.

So he flames out with mucho gas in the external tanks and finally ejects on short final at Hill.

Plane hits overrun and burns like crazy due to all the trapped gas in the external tanks.

Least the pilot ejected safely. I'll say this for the 1000th time - super seat and was damned glad I didn't have to use it.

out,

Hi guys,

During flight the external tanks will loose the fuel first. All this because when entering the combat zone you won't have to deal with heavy tanks and just jettison the empty fuel tanks so you still have a aircraft with lots of fuel internal to complete the combat mission. And you won't have to deal with highdrag external tanks.

During the aerial refueling the external tanks will be depressurized and the internal tanks go to a lower pressure so they will still feed the engine.

henkster and skunkworks
------------------------------>
what will a pilot do without a crewchief?

I'm not trying to sound rude but... This is about the 5th thread lately that someone has rehashed just to answer a question already previously answered. Not to say that people's knowledge isn't appreciated.

Can anyone tell me which one among the F-16 fuel tanks is capable to withstand supersonic speeds ? Is it the 1134 Liters tank, or the 1400 L one ?
Thanks for the reply... Cool

I know them as 300G and 370G, or centerline / wing tanks respectively. Both are good up to 1.6M or 600KCAS. I've tried supersonic with both without any noticable effects. I've never flown with 600G or conformals, and don't plan to.

600 can go 1.2 if I remember correctly... I think that was based on the old Block 25..... could only get as fast as 1.2 with the tank.

Cylon

Does someone has got some plans of it? blueprints or how do you call it.
maps?

Whity, the fuel system is FR and AL not LA. They stand for aft left and forward right. Did you learn all that from the game?

Gums wrote:

Absolutely awesome explanation Whity!

Hell we taught this stuff back in '79 and it doesn't look like it has changed. Guess a good idea is a good idea.

BTW, the first crash was a troop that left the air refuel door open. Was in a B-model, so he also had the flaps down, causing even more fuel flow problems.

Nowadays (i do not know how it was in the good old days) the flaps will not come down when flying with the Air refuel door open, they will only come down when you either lower the Landing gear handle or select alt flaps. The Viper will go into Takeoff and landing gains however, meaning that the roll rate is limited and it is pitch rated.

Cheers

Forum: F-16 Procedures

External/Internal fuel tank sequence