Fuel Consumption

[middle]

Waht is the generally approved order of consumption for fuel usage on multi-tamked planes, i.e. planes with wing tanks, belly tanks, etc.

Does one use the fuel in the wing tanks first? Or the belly tanks? I've been wondering about this for awhile...:isadizzy:

[Willy]

MoparMike explained it me once, but I've lost the text file that I copied it to. But he knows it.

[WND]

Hi Middle:

From my flying experience I always used my "aux" tanks first.

SInce you take off and land on your "mains", I would take off on the mains (that usually have fuel gauges), set up my fuel flowage, then switch to my "aux" tank (tips or belly) and "time it" since most of the time you don't have fuel gauges on "aux" tanks... That way when your 'aux" tanks run out and you have to switch back to your mains, at least you'll have gauges to guide you by and hopefully they'll be calibrated correctly!!!

I also would try to burn off the extra fuel first so as to get the balance back to the center of the airplane. (ie: tip tanks or wing drop tanks) To make your flying easier and more enjoyable, you always play the "balance" game!!

Keep in mind that this is the way I use to do it - I'm sure other pilots had different scenarios..

I will assume that if there are several "center" tanks involved (forward / back), again you play the balance game so the aircraft "CG" remains inside the cg envelope..

Altho I was never a pilot in a war, I believe they used up their drop tanks first so they could get rid of them in case they got into aerial combat.

On the Mustang my brother once owned, he had 45 gal "wet tips" that fed thru the mains so we would take off, burn off about 50 gals out of the mains then pump out the tips and verify it by the fuel gauge..

Anyways, I hope this helped ya..

Bill

PS: There are exceptions to the rule tho!! I believe the "tips" on a T-33 (and maybe even a Cessna 310 or a MU-2) are considered "mains" so then yes - you would burn off the mains first and your "center" tank would be your last one - you DON'T want all that extra weight hanging way out their any longer than you have too - especially when your trying to land...

[Ashaman]

Well, usually the order of usage of the tanks in the planes I fly (Calclassics Constellations, mainly) on long range flights is to drain the center tanks first (so to reduce the weight of the fuselage on the wings struts as soon as possible), then proceed with the other wings' tanks in a precise order.

Of course on other planes there are other procedures. I only know mine. :ernae:

[middle]

Thanks guys. Willy, I hope Mopar will see this....Now that I have a nice stick (altho I've yet learned how to program it...it's got a shift button that creats endless possibility)and pedals, I've been trying to fly as realistically and authentically as possible.

[srgalahad]

There's a difference between manually running the fuel selectors and what FS does by default.

I think the info was in one of the "lost threads" but IIRC, when no fuel selector is used, or set to "ALL" the default FS sequence is Aux/tips (if any) non-main center tanks, mains... assuming all (or some combination) are listed and enabled in a given a/c.

An example of a manual sequence: I just ran a DC-3 (3 tank) flight. T/O on mains and climb to cruise. Switch both engines to "Aux" and run dry (cough) then back to "Main Left on left, Main right on right engine" til landing. The DC-3 has a fuel gauge selector switch that shows the qty. in each tank (not a FEED selector - that's separate) so it's easy to check. A lot of models don't model the fuel system and/or gauges correctly so it will vary with each plane.

As Bill pointed out, balance is important. I've had a few surprises on approach as I've let the tanks get out of balance (mostly left/right) and it can be difficult to fly an approach and landing with one wing wanting to go low due to the extra weight on one side.

Nice to see someone want to try things like fuel management as I suspect that 90% of sim pilots just "push start and go"

Rob

Rob

[PRB]

I think it’s fair to say that it depends on the plane. Different planes have different tank configurations, and different weight & balance considerations. If “tank 4” is the feed tank to the engines, this one must obviously remain full as long as you have gas. The Constellation has four feed tanks, one for each engine, while the B-24 has one single tank that feeds all four engines. These facts affect fuel management decisions. The P-51 likes to have the center fuselage tank emptied first for CG reasons. Usually if drop tanks are carried, they are drained first. All this assumes that the FS model has a realistic fuel system, and not simply the “all tanks on” system of most FS planes.

[Willy]

I'm pretty sure on the AH Spitfire XIX that it goes, wingtip tanks, small wing tanks, large wing tanks then upper main tank with the lower main tank going last.

[miketull]

Excerpt from POH;"Filling the fuselage tank to the 85-gallon capacity may cause an aft CG condition beyond limits; therefore, the fuselage fuel tank is placarded for 65 US. gallons and should never be filled above this quantity." I heard Col. Bud Anderson say in a video that they would take-off with 85-gallon in the fuselage tank, however with the fuel selector set to the right main tank. This was done because the fuel return line from the carburetor pumped fuel back into the right main tank. If you don't use the right main for 15 minutes then you would be pumping fuel overboard. The other problem with using drop tanks is that sometimes they wouldn't draw fuel. The drop tanks have no booster pumps, but fuel is forced from them by a control pressure of 5 psi. from the exhaust side of the vacuum pump. If the engine quits when you switch to a drop tank there is no guarantee that you will be able to start the engine by switching the fuel selector valve back to one of the main tanks. So it is better to make sure that your drop tanks will draw fuel while your'e still in the pattern in case you have to make a deadstick landing. After making sure that both drop tanks are feeding properly and having burned 15 minutes of fuel out of the right main tank then switch to the fuselage tank and pull it down to 65 gallons and then start alternating between left and right drop tanks at fifteen minute intervals until the fuel in the drop tanks is exhausted or you have to jettison them to engage the enemy.

[middle]

Thanks for all this info guys, it really helps. Yeh, I've been on an adventure to attempt to fly 'em right.....it's pretty satisfying to figure it out and have it all work right. There was a time when I just hit the power and flew but I'm finding that at least with some planes that if I follow the procedures that I get more speed out of them and just generally have an easire time of suspending disbelief. Ya nevr know..one of these days I could be flying somewhere and the pilot could pass out or something equally weird and at least I know enuff now to have a fighting chance at survival,lol.

[fliger747]

Tactical aircraft use the droppable tanks first, then tanks further away from the CG so as to optimize manuverability. Transport aircraft, which generally carry a bigger proportion of fuel, will try to reduce bending moments on the wings by using fueselage and inboard tank fuel (to a certain extent). In the 747-400 we use center tank fuel first, then inboard wing fuel. As the inboard fuel nears the outboard tank fuel, the tip reserves drain into the inboards. When all wing tanks are equal, we go tank to engine so all tanks drain at the same rate. This procedure minimizes wing spar stress, a consideration when you have a takeoff weight pushing toward 900,000 Lbs...

T.