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Fuel selector location?
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a.s.elliott(at)cox.net
Guest

Posted: Sun Nov 04, 2007 3:16 pm Post subject: Fuel selector location?

Another finishing detail question:

  

 I have the standard Andair L-R-Off fuel selector from the kit.  I have  seen most aircraft with the selector mounted on the center console.  Since  there is no "both" position, we have to change tanks regularly in order to  maintain fuel balance.  So the selector ought to be in an easily accessible  place.  Clearly the center console is such a place, but... 

  

 In order to conserve valuable console space, and also to avoid an  extra high spot in the fuel system, I was thinking of mounting the selector on a  raised bracket on the floor, to the left of the center tunnel, forward of the  controls (dual stick), and aft of the heel support.  The "out" line  would then run through a grommet back into tunnel and then forward to the  firewall.  So my question is for people with flying aircraft:

  

 Would that location be relatively easily accessible in flight?   Or would it be an uncomfortable contortion to reach it?

  

 Thanks,

 Andy Elliott, Mesa, AZ

N601GE (reserved)

601XL/TD/QB, Corvair,  building...

  

  

   [quote][b]

purplemoon99(at)bellsouth
Guest

Posted: Sun Nov 04, 2007 3:40 pm Post subject: Fuel selector location?

    Andrew,I thought that Andair made a switch that had  off,left,right,and  both,I was thinking about getting one  .  FS20x4 is there number  I just looked it up , if it is any help   Joe  N101HD601XL/RAM

 [quote]   ---

Ron Lendon

Joined: 10 Jan 2006
Posts: 685
Location: Clinton Twp., MI

Posted: Sun Nov 04, 2007 5:39 pm Post subject: Re: Fuel selector location?

Please try this at home.



Fill a glass with water. Take two drinking straws and place both in your mouth.  Check the seal, place one straw in the water and the other outside the glass.  Draw the water up the straw.  Doesn't work does it?  That is why the low wing doesn't have a both setting on the fuel selector.

_________________
Ron Lendon
WW Corvair with Roy's Garage 5th bearing
CH 601 XLB
N601LT - Flying
http://www.mykitlog.com/rlendon
Corvair Engine Prints:
https://sites.google.com/site/corvairenginedata/

archerm

Joined: 01 Jan 2007
Posts: 21
Location: Wichta

Posted: Sun Nov 04, 2007 6:18 pm Post subject: Fuel selector location?

I had similar concerns about raising the location  of the fuel selector.  I moved it down to keep it as low as possible.   I wanted to make sure that there is a pressure head on the fuel selector.   I then used an extension to keep the selector within easy reach.  You can  see it on this page of my website.

  

 http://www.zodiacxl.com/Brake%20and%20Fuel%20system.htm

  

 While I understand the need to conserve  space.  I also look at the functional priority of the systems on the  aircraft.  Fuel system management rates pretty high in  my priority.  When we look at accident statistics  fuel management is one of the major failures.  So in my panel it  is where I can get to it.

  

 Good Luck

  

 Matt 

 www.zodiacxl.com

  

  

  

 [quote]   ---

_________________
Matt
www.zodiacxl.com

purplemoon99(at)bellsouth
Guest

Posted: Sun Nov 04, 2007 6:18 pm Post subject: Fuel selector location?

Ron, Couldn't you run off of BOTH with both tanks full for the" top 

half ", I only fly from the top half any way,then it's time to re fuel. I 

dont see why you couldn't fly off the frist 3/4 of the tanks ,then switch 

back and forth between LEFT and RIGHT ?    Joe N101HD 601XL/RAM

---

purplemoon99(at)bellsouth
Guest

Posted: Sun Nov 04, 2007 7:17 pm Post subject: Fuel selector location?

Look'slike It's going to be hard as hell to change  that filter  after you get the plane built, beatiful with the rest of the  work... Joe N101HD 601XL

 [quote]   ---

psm(at)att.net
Guest

Posted: Sun Nov 04, 2007 7:57 pm Post subject: Fuel selector location?

Hi Joe,



I couldn't resist commenting on this topic.



It is one of the "Nature of the Beast" issues that you must directly 

control the fuel source in low wing airplanes.  It has something to 

do with the physics of liquids and the way gravity works as opposed 

to the way pumps work.



In a liquid, the pressure increases with the depth of the 

liquid.  This means that when using gravity feed from high wing 

tanks, the tanks will tend to equalize their height so you get 

roughly the same amount of fuel from each tank when the lines from 

the tanks are connected.  This is what you get when you use "Both" 

tanks in a high wing plane.



In a low wing plane, a pump must be used to raise the fuel from the 

tanks to the engine.  If you gave the pump a choice, it would take 

its fuel from which ever tank had the lowest pressure.  That means 

the pump would always take its fuel from which ever tank had the 

least fuel.  With this arrangement you would never get any fuel from 

the tank with the most fuel in it.  This is not what you want in an 

airplane.  The normal solution is a selector switch that allows the 

pilot to draw fuel from which ever tank he chooses.



In Piper low wing planes, the normal way to control the fuel is to 

start with one tank (usually the left tank for some unknown reason) 

and burn around 1/2 hour from it.  Then you switch to the other tank 

and burn from it for an hour.  At this point you should be finished 

with your flight, but if not you switch to the first tank and burn 

another hour from it.  For takeoff and landing you always switch to 

the tank with the most fuel.



It sounds like a lot of work for a pilot used to high wing planes, 

but you will get used to it quickly.  There just isn't a better way.



Paul

XL fuselage





At 06:14 PM 11/4/2007, you wrote:

 	  Quote: 	
		       Ron, Couldn't you run off of BOTH with both tanks full for the" 

 top half ", I only fly from the top half any way,then it's time to 

 re fuel. I dont see why you couldn't fly off the frist 3/4 of the 

 tanks ,then switch back and forth between LEFT and RIGHT ?    Joe 

 N101HD 601XL/RAM

bryanmmartin

Joined: 10 Jan 2006
Posts: 1018

Posted: Sun Nov 04, 2007 8:21 pm Post subject: Fuel selector location?

If you forget to switch to left or right only and the engine quits because its sucking air instaid of fuel, which tank do you switch to to regain power? You may not get any clue from the guages at that point, so you've got a 50-50 chance. It may take a few seconds to get fuel flowing again even if you guess right, and if you guess wrong you've wasted valuable time that you might not have to waste. It's best not to have a both position at all. That way if you run one tank empty you know which tank to switch to to try for a restart. No guessing.



[quote]--> Zenith-List message posted by: "Southern Reflections" <purplemoon99(at)bellsouth.net (purplemoon99(at)bellsouth.net)>

    Ron, Couldn't you run off of BOTH with both tanks full for the" top half ", I only fly from the top half any way,then it's time to re fuel. I dont see why you couldn't fly off the frist 3/4 of the tanks ,then switch back and forth between LEFT and RIGHT ?    Joe N101HD 601XL/RAM

---

_________________
--
Bryan Martin
N61BM, CH 601 XL, Stratus Subaru.
do not archive.

purplemoon99(at)bellsouth
Guest

Posted: Sun Nov 04, 2007 8:37 pm Post subject: Fuel selector location?

Hi Paul, It's always good to to get your input,you have a way with words.I 

now understand it very clearly ,so it's the Left or Right switch for 

me...just didn't know about the pressure aspect,. Thank,s     Joe N101HD

---

purplemoon99(at)bellsouth
Guest

Posted: Sun Nov 04, 2007 8:39 pm Post subject: Fuel selector location?

that's true too Bryan, This list is worth it's  weight in gold, most of the time.. Thank's   Joe N101HD

 [quote]   ---

notsew_evets(at)frontiern
Guest

Posted: Mon Nov 05, 2007 4:34 am Post subject: Fuel selector location?

Paul and you guys.

I learned to fly in 1965 in a BeechCraft.  I was taught from day one to use 

the left tank first because in the "bigger" airplanes the fuel pump would 

feed fuel to the engine.  Any excess fuel that wasnt needed by the engine 

would be returned by the system to the left tank...

Using the right tank first and having excess returned to the left would 

allow fuel to overflow out the vent....

I ve always "assumed" that was the straight scoop and never questioned my 

instructor. Instructors are experts, now I are one...



SW

---

archerm

Joined: 01 Jan 2007
Posts: 21
Location: Wichta

Posted: Mon Nov 05, 2007 9:34 am Post subject: Fuel selector location?

Actually with the access panel up top.  It  isn't that bad to change or remove the filter.  I considered putting it in  the engine compartment but was concerned about heating.   With  out the removable panel it would be tough.

  

 Matt

  

 [quote]   ---

_________________
Matt
www.zodiacxl.com

psm(at)ATT.NET
Guest

Posted: Mon Nov 05, 2007 8:17 pm Post subject: Fuel selector location?

Hi Steve,



Thanks for adding to the tank choice discussion.  I think I have the 

whole picture now.



I believe fuel injected aircraft engines require a fuel return 

line.  This somehow returns excess fuel from the injection pump to 

the fuel tank.  I guess there is a standard that in small low wing 

planes, the left tank is the return location of choice.  That makes 

the left tank the best choice for first fuel burn.



While there is no necessary relationship between big planes and fuel 

injection it is an advanced feature that can often be found on more 

expensive planes.  I have more hours in the C-172XP than any other 

plane.  This has a Continental IO-360 installed - a 6 cylinder fuel 

injected engine.  It is the smoothest running airplane engine I have 

ever experienced.  I have also flown a Piper Arrow with a Lycoming 

IO-360 which has only 4 cylinders and doesn't run nearly as smoothly.



Paul

XL fuselage

At 04:32 AM 11/5/2007, you wrote:

 	  Quote: 	
		  Paul and you guys.

I learned to fly in 1965 in a BeechCraft.  I was taught from day one 

to use the left tank first because in the "bigger" airplanes the 

fuel pump would feed fuel to the engine.  Any excess fuel that wasnt 

needed by the engine would be returned by the system to the left tank...

Using the right tank first and having excess returned to the left 

would allow fuel to overflow out the vent....

I ve always "assumed" that was the straight scoop and never 

questioned my instructor. Instructors are experts, now I are one...



SW

notsew_evets(at)frontiern
Guest

Posted: Tue Nov 06, 2007 5:45 am Post subject: Fuel selector location?

Paul



I guess my early training was just to get me used to procedures for 

"furture"  flying.

When I switched to Cessna it seemed soooo easy to transition to less complex 

designs.

SW

---

John Bolding

Joined: 23 May 2006
Posts: 281

Posted: Tue Nov 06, 2007 6:05 am Post subject: Fuel selector location?

 	  Quote: 	
		   

 Hi Joe,

 I couldn't resist commenting on this topic.

 In a low wing plane, a pump must be used to raise the fuel from the tanks 

 to the engine.  If you gave the pump a choice, it would take its fuel from 

 which ever tank had the lowest pressure.  That means the pump would always 

 take its fuel from which ever tank had the least fuel.  With this 

 arrangement you would never get any fuel from the tank with the most fuel 

 in it.  This is not what you want in an airplane.  The normal solution is 

 a selector switch that allows the pilot to draw fuel from which ever tank 

 he chooses.



 Paul

 XL fuselage


	




Paul,  Maybe I need to learn something here,  WHY would the pump draw fuel 

from the tank with the lowest pressure (emptiest)??



That has not been my experience (2000 hrs in an RV3) , my tanks empty 

equally with one pump sucking on both tanks at the same time.

  LOW&SLO   John Bolding

notsew_evets(at)frontiern
Guest

Posted: Tue Nov 06, 2007 6:31 am Post subject: Fuel selector location?

I wonder why they dont tie the two tanks together with an "equalizer" 

pipe...  Then both tanks would keep the same level of fuel....

Actually thats how a high wing airplanes works.  The two tanks tie together 

and you dont need to swap left/right tanks...

sw

----- Origin



al Message ----- 

From: "John Bolding" <jnbolding1(at)teleshare.net>

To: <zenith-list(at)matronics.com>

Sent: Tuesday, November 06, 2007 7:03 AM

Subject: Re: Re: Fuel selector location?

 	  Quote: 	
		   

 <jnbolding1(at)teleshare.net>





> 

> Hi Joe,

> I couldn't resist commenting on this topic.

> In a low wing plane, a pump must be used to raise the fuel from the tanks 

> to the engine.  If you gave the pump a choice, it would take its fuel 

> from which ever tank had the lowest pressure.  That means the pump would 

> always take its fuel from which ever tank had the least fuel.  With this 

> arrangement you would never get any fuel from the tank with the most fuel 

> in it.  This is not what you want in an airplane.  The normal solution is 

> a selector switch that allows the pilot to draw fuel from which ever tank 

> he chooses.

>

> Paul

> XL fuselage

 Paul,  Maybe I need to learn something here,  WHY would the pump draw fuel 

 from the tank with the lowest pressure (emptiest)??



 That has not been my experience (2000 hrs in an RV3) , my tanks empty 

 equally with one pump sucking on both tanks at the same time.

  LOW&SLO   John Bolding

lrm(at)skyhawg.com
Guest

Posted: Tue Nov 06, 2007 7:09 am Post subject: Fuel selector location?

Sometimes you want to burn off one side or the other to offside a heavy side 

or wing.  Makes it fly more gooder.  Larry

---

Tim Juhl

Joined: 21 Mar 2006
Posts: 488
Location: "Thumb" of Michigan

Posted: Tue Nov 06, 2007 8:25 am Post subject: Re: Fuel selector location?

Older Cessna I72's are placarded requiring flight on a single tank above 5000 feet.  Apparently there is a greater risk of vapor lock in such aircraft that was due to the unvented caps and single vent line running between the two tanks.  Later models are not placarded but I'm not sure exactly what they did to correct it besides the AD requiring use of a special cap that would vent in case of a vacuum in the tank.



I'm not big on doing a lot of experimenting on the fuel system.... keep it simple and go with what is known to work.  In my experience, seemingly inconsequential changes can sometimes lead to unintended consequences.



Tim

_________________
______________
CFII
Champ L16A flying
Zodiac XL - Jabiru 3300A
Almost done! It'll fly in spring!

psm(at)ATT.NET
Guest

Posted: Tue Nov 06, 2007 9:19 am Post subject: Fuel selector location?

Hi John,



I stand corrected.



Your message got me to do an experiment in my kitchen.  I took two 

identical glasses and put 2 ounces of water in one and 6 ounces in 

the other one.  I then took a big suck on two identical 

straws.  Measuring the remaining water in the glasses I discovered 

there was one ounce taken out of each one.  So, as you suggested the 

water was not taken from the lower level "Tank" but taken equally 

from both tanks.



You will notice this is not the same as the behavior of two gravity 

fed tanks which will tend to equalize their levels.  I started with 6 

and 2 ounces and ended with 5 and 1.  In a high wing model I would 

have ended with 3 and 3.



So, I was wrong, but the "Both" solution still doesn't work for low 

wing planes.



Paul

XL fuselage

do not archive

At 06:03 AM 11/6/2007, you wrote:



 	  Quote: 	
		  Paul,  Maybe I need to learn something here,  WHY would the pump 

draw fuel from the tank with the lowest pressure (emptiest)??



That has not been my experience (2000 hrs in an RV3) , my tanks 

empty equally with one pump sucking on both tanks at the same time.

  LOW&SLO   John Bolding

Trainnut01(at)aol.com
Guest

Posted: Tue Nov 06, 2007 9:41 am Post subject: Fuel selector location?

Hey Paul

  

 If you keep sucking you'll find that when the lower level "tank" runs  dry you will no longer be able to get "fuel" from the higher level "tank" even  though it still will contain about 4 ounces.

  

 Carroll

  

 do not archive



See wh [quote][b]

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