keifer@uiucdcs.CS.UIUC.EDU (03/09/86)
I am a student pilot (soloed) finishing the Private Pilot certification at the University of Illinois. We fly Beechcraft Sports here (BE-19-180) which have fuel selector knobs to switch tanks. We've been taught that the most common cause of engine failure is fuel starvation, and that this is most common when you forget to switch tanks. Why don't they make airplanes so that both fuel tanks supply fuel to the engine at the same time? Seems like this would make things a lot easier. You wouldn't forget to switch tanks, since you wouldn't have to. Any comments? Gunnar Seaburg c/o keifer@uiucdcs
ark@alice.UucP (Andrew Koenig) (03/11/86)
> Why don't they make airplanes so that both fuel tanks supply fuel to > the engine at the same time? Seems like this would make things a lot > easier. You wouldn't forget to switch tanks, since you wouldn't have > to. They do. They're called Cessnas. It is apparently easier to go without switching tanks in a high-wing airplane than a low-wing airplane. The smaller Cessnas tend to have a fuel selector marked "L - Both - R - Off" You still want to be able to use only one tank in case drawing fuel unequally from the two tanks causes a weight unbalance during extended cruising flight.
ralph@inuxc.UUCP (Ralph Keyser) (03/13/86)
> Why don't they make airplanes so that both fuel tanks supply fuel to > the engine at the same time? Seems like this would make things a lot > easier. You wouldn't forget to switch tanks, since you wouldn't have > to. Cessna has heard your request. Dash over and check out the fuel system on a Cessna single. They have a left-both-right-off selector, and most of the time you just park it on both and leave it. The handbook suggests selecting left or right during refueling, and you need to be able to select a single tank for balancing if you get uneven fuel burn or if you have contamination in one tank. The argument against this system is that it fails to teach you anything about fuel management - a skill needed in most twins and other complex aircraft. The statistics, however, show that the simple Cessna fuel system leads to fewer fuel mismanagment accidents than any other types of aircraft. Cessna pilots, alas, still manage to run out of fuel, just like everyone else. Ralph Keyser Archer 8320C
Hughes.WBST@XEROX.COM (03/14/86)
Gunnar They do make airplanes like this. Most of the ones I know about are brand Cessna. Specifically the Cessna 150 and 152 which are good trainers have a fuel on/off and that is it. Both tanks feed all the time. Bill
Hughes.WBST@XEROX.COM (03/14/86)
"You still want to be able to use only one tank in case drawing fuel unequally from the two tanks causes a weight unbalance during extended cruising flight." To avoid this you fly with the wings level. When you fail to do this for a while you can tip the wings a bit (raise the one with the most fuel) and the fuel will follow the old rule that a liquid seeks it's own level. What you did not mention and to me is a stronger reason for switchable tanks is what happens if you have lots of fuel but the engine sputters or quits. It could be due to water in one tank. With the fuel selector you can try the other one. Without the selector, you look for a place to land real quick (you probably do this any time something uncool happens--- if you are not always looking for a place to land just in case, which is an excellent idea). Bill
good@pixar.UUCP (03/14/86)
In article <7900035@uiucdcs>, keifer@uiucdcs.CS.UIUC.EDU writes: > > Why don't they make airplanes so that both fuel tanks supply fuel to > the engine at the same time? Seems like this would make things a lot > easier. You wouldn't forget to switch tanks, since you wouldn't have > to. > I'm sure that Cessna pilots are going to mention the fact that many high-wing planes do indeed have a "both" fuel selector position. This is generally practicable only when using gravity to move the gas around. Low- wing planes tend to have the off-left-right variety. Whatever you fly, make darn sure you know which your plane has. Some high-wing planes do have an "off" position. Some very short flights have resulted from fuel selector confusion. Checking that this selector moves, and is coupled to the knob, is the *very first* item on the pre-flight I was taught. This is the result of learning about an accident where a pilot was flying IFR, took off on one tank, ran it near dry and then went to switch tanks. The selector knob sheared off the shaft and he died in a fuel-starvation induced crash with a full tank of fuel in one wing. A very helpful technique I've found for remembering to switch tanks is to watch the minute hand on the clock. If the hand is on the right side of the dial, use the right tank. When it is on the left side, use the left tank. This gets you a switch every 30 minutes which, in the Warrior at least, is just peachy for keeping the weight balanced, etc. --Craig ...ucbvax!pixar!good
ark@alice.UucP (Andrew Koenig) (03/17/86)
> Some high-wing planes do have an "off" position. > Some very short flights have resulted from fuel selector confusion. All airplanes have an "off" position. Certification requires that it be possible to shut off all fuel past the firewall in case of an engine fire.
Campbell.SV@XEROX.COM (03/17/86)
They don't do it because it would cost money. High wing airplanes such as the 152 or Skyhawk do have a both position. Gravity ensures a steady flow of fuel. On a low wing airplane, which uses a fuel pum,p you have to have a central header tank that both fuel tanks would feed into. The engine would be driven by this tank which would always have fuel in it even with the wings banked. But it costs more money and the header tank takes up room and reduces the load of the airplane because of it's weight. But it can be done. I know this for a fact because my Swift does have a header tank and the fuel switch only says on or off, not left, right and off. Rick Campbell N3344K
brent@poseidon.UUCP (Brent P. Callaghan) (03/19/86)
While we're on the subject of tank switching - it's
a good idea to select the fullest tank BEFORE you
do the pretakeoff runup. Switching tanks just before
takeoff is not a good idea.
--
Made in New Zealand --> Brent Callaghan
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