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One empty gas tank????


procharger

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I'm not willing to say I will never screw the pooch on fuel, I can only say I'm pretty paranoid about it. My big fear is that once I get to doing some really long flights in the CT I will misjudge fuel burn, ground speed, or winds and get in a low fuel state. That said, as I mentioned I am paranoid about fuel, and can't really see myself not checking the sight tubes for a period long enough to get to a critical fuel state with no available airports.

I suggest you track fuel use a minimum of two ways: fuel burn (gph * engine time) and gauge. Be on the ground with the most pessimistic method.
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on the prevention side... let's make this simple.

'Flying along and notice one side is showing nearly empty, and the other side shows more. What's a good way to remember what corrective flight action is needed to remedy the situation? (besides landing)

Even simpler: To help alleviate the situation, and take advantage of the side with the most fuel, should the ball be hanging towards the empty side or the fuller side???

Tim

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Ed,

 

You're thinking too much inside the box.

It's not always physics, it is sometimes mechanical and there are always exceptions because there are many factors. Mechanical, physics and pilot. Come work with me and I'll show you mechanical. Think of anything and every thing that may stop or slow fuel delivery through the system. It just isn't about fuel flow out the wing fitting and it isn't always just flying uncoordinated.

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Roger,

  • To meet fuel tank design criteria the flow rate needs to be something like 4gph per side.
  • Most of the time we are using a little more than 1/2 of its capacity. (flowrate per side)
  • Pressure is provided by gravity or Gs so it matches left to right
  • There are 3 directions fuel can flow
    • towards engine
    • towards left wingtip
    • towards right wing tip

With pressure being equal and capacity not a factor it all comes down to direction. Gravity or Gs when coordinated vector towards the engine and yaw forces vector towards a wingtip. One wing tank has all forces directed towards the engine and the other wing tank has them divided with one component towards the engine and the other component towards its outboard end.

 

The final consideration is that the CT does not have a panel in a fixed position but rather a binnacle that isn't even fastened and the face of the binnacle is canted to boot.

 

Mechanical restrictions don't come into play because the required flowrate is so high.

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I always have had problems with the "fuel follows the ball" thing... maybe because of the saying "step on the ball" for coordinating flight.

Maybe it'll help if I try to remember "ball towards the empty side". They say it's easier to remember something if you make a song about it... any songwriters out there?

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Why not set a personal limit on how low you will let your fuel get? If you are going to get below that, plan a fuel stop. If one fuel stop is not enough, plan 2 fuel stops. If unexpected headwinds are going to put you near your limit, make an unplanned fuel stop.

 

Flying is not driving, and requires a whole different mindset.

 

I remeber a flight from North Las Vegas to Mammoth Yosemite about 4 years ago. 34 Gallons of fuel on board for a flight that takes between 1.7 and 2.4 hours. Weather 30 miles north stopped me and after 2 attempts to penetrate I headed back for Las Vegas and skirted the Bravo and crossed the Red mts and flew towards Mammoth via Pahrump, this added time but I had enough fuel to make the trip 3 times.

 

My girfriend was getting sick so we descended to near sea-level to land Furnace Creek which gave me a close view of Zabriskie Point at sunset that was once in a life time but the landing at Furnace Creek was beyond my ability so I headed for Stovepipe Wells and even though the heading was a big change it remained beyond my landing minimums.

 

So I climbed 10,000' and headed back towards Mammoth thinking that Bishop would be my choice. The end was uneventful but I did manage to use over 20 gallons on a flight that I have done in 8 gallons. When gas stops are hours apart and conditions mandate sometimes there can be very few fuel stops available.

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Tim, i never could remember the fuel following the ball crap ..but maynbe i can remeber ball to empty side......maybe a song about

"empty balls"? maybe a christmas jingle?

 

I always have had problems with the "fuel follows the ball" thing... maybe because of the saying "step on the ball" for coordinating flight.

Maybe it'll help if I try to remember "ball towards the empty side". They say it's easier to remember something if you make a song about it... any songwriters out there?

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Dude, he was giving you valid advice, you didn't need to jump on him...

 

It's an accepted practice in flying that if you are going to run the tanks to near empty, to drain one tank until it's running on fumes, that way the other is still showing up on the gauge. It's easier to read one tank with 5 gallons of fuel, than two tanks with 2.5 gallons (both sight gauges and electric/electronic gauges are more accurate with more fuel). It's not a practice I like to perform personally (I love seeing lots of fuel in the tanks), but I do it if I need to drain the tanks on the way to the shop (like if we are taking the wings off).

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Point/Counterpoint:

 

Point: A pilot should understand the functioning of virtually every control in his or her aircraft. Similarly, every placard and instrument marking should be understood.

 

As an instructor, I would sit in the cockpit and point to various controls and markings to see if the student understood them.

 

For instance, back in the day of turn coordinators, they often had "2 MIN" on the front:

 

coordinator.jpg

 

I would ask the student what that meant and, right or wrong we could use that as a springboard for discussion about standard rate turns, angle of bank needed for that turn, and so on.

 

So, a student, or any pilot, for that matter, should understand what a fuel selector valve could be used for, and the correct terminology in describing it (hint: it's not generally referred to as a "switch" among pilots and mechanics).

 

 

Counterpoint: I have no issue with an instructor deciding that a fuel selector valve, if installed, be kept in the "BOTH" position at all times in training (unless the engine is on fire). Keeping it simple for the student can be a worthy goal, and I'd expect that fuel management via tank selection could wait until after the pilot is certified.

 

 

And a note: very few, if any, low wing planes have a "BOTH" position, so understanding the function of a "LEFT/RIGHT" selector makes one a better all around pilot. The Cirrus has a maximum 10 gal imbalance stated as a LIMITATION, so at 17.6 gph (standard in the turbo) there's very regular tank switching going on to stay within lateral balance.

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hint: it's not generally referred to as a "switch" among pilots ...


Eddie,

Read my post again, I referred to it as a valve not a switch. I was reviewing this doc http://www.faa.gov/r...ia/ama_ch14.pdf and saw that the FAA uses the phrase 'when switching to a new tank' and I referred to the result of the action as 'switched incorrectly' similar to the FAA language.

The important point in my post is that the more complex valve does not protect you from fuel starvation due to one tank being empty ( or off ) and the other tank's fuel unported.

Edit: I just noticed that our ctlsi guy referred to 'it' as a 'giant toggle switch', hmmmmmm is the valve controlled from a toggle switch or is that what you were correcting?
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CT,

 

Your post was fine. We do in fact, switch tanks using a selector valve.

 

I was referring to this:

 

How big is the switch on your airiplane?

 

I know CTLSi hates to be corrected on spelling or terminology, but I thought it was worth pointing out for the other students and new pilots so that they don't fall into poor habits.

 

Most pilots I know pride themselves on proper terminology, but if one just doesn't care, so be it.

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Ed,

 

You're thinking too much inside the box.

It's not always physics, it is sometimes mechanical and there are always exceptions because there are many factors. Mechanical, physics and pilot. Come work with me and I'll show you mechanical. Think of anything and every thing that may stop or slow fuel delivery through the system. It just isn't about fuel flow out the wing fitting and it isn't always just flying uncoordinated.

 

Roger,

 

http://www.faa.gov/r...ia/ama_ch14.pdf Design requirements suggest a flow rate of about 4 gallons/hr per side and we use just over 1/2 that so any and every little thing that might slow delivery is not at play.

 

Pressure comes from gravity and Gs so there is no differential there.

 

There are 3 vectors:

  1. towards engine
     
  2. towards left wing tip
     
  3. towards right wing tip

As you position the fuel system relative to the forces acting on the fuel you go from using the vector towards the engine exclusively to adding a component towards a wing tip (when introducing yaw forces). The result is you now have 1 wing with fuel motivated to flow towards the engine only while the other wing is motivated to flow at least partially towards the wing tip, this wing cannot drain as fast the fuel is stopped or at least restricted on its way to a wingtip vent.

 

A CT has a binnacle not a panel and the binnacle does not have a 'square' face nor is it even fastened. The result is a suspect slip/skid ball and add that to the lack of a visible cowling and a design that is quite happy in a slip and you find the problem. We all have sight tubes that can be used to verify our balls, you can even learn to coordinate or slip by referencing a sight tube instead of the ball.

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Remember also that you are much better off entering the pattern with one tank showing 5g instead of two tanks showing 2.5g. Another good reason you might want to run a single tank toward the end of a trip...you won't have to worry about unporting tanks in the pattern. Though with the header tank it's not as big a problem. I kind of wish the CTSW had a header, even if it didn't have a selector.

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Statistically the left and right options are more dangerous than on or both. I would always use both If I had the option.

 

Questions:

  • if you unported wing with remaining fuel while doing a turn in the pattern, what would happen? Anything?
  • If you unported wing with remaining fuel while doing a forward slip on a strait in how long would you have to slip before the engine would starve?
  • If you unported wing with remaining fuel while doing a forward slip on a strait in could you reverse the fuel flow in the fuel lines and put fuel back in the tank limiting you to only what is in the float bowl?
  • How long can you idle on float bowls alone?
  • What if you advanced the throttle on float bowls alone, would there be anything there?

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Statistically the left and right options are more dangerous than on or both. I would always use both If I had the option.

 

I believe it.

 

Several years ago, probably more, a Spernak Airways C-207 lost power coming in to Merrill Field in Anchorage. Pilot put it down in a sports complex in front of a baseball game including TV cameras covering the game. Everyone walked, nobody on the ground was hurt. Plane was a mess. Oh what a good pilot he was proclaimed the talking heads. That is, until it was determined there was 34 gallons in the other tank.

 

A C-207, like a C-206, only has L, R, or off choices with the fuel selector. When his engine quit he was about 500 ft AGL on base for what was then runway 33 and no hope of making the runway or a restart. He had neglected a proper pre landing check.

 

As for his altitude, all aircraft were that low on a long base to remain below the traffic on the main runway, at that time 6-24.

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What is that thing on the front of the airplane that spins called? That one always stumps me, so I call it a whirl-a-ma-thingie.

 

Andy. - proper terminology is "pilot cooling fan". We know this because, should it stop, you can see the pilot start to sweat. :)

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